EvaluacióN De La VíA AéRea2 Copia
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EvaluacióN De La VíA AéRea2 Copia
- 7. Ventilación con ML difícil “ Incapacidad de poner la máscara con tres intentos en una posición satisfactoria que permita una adecuada ventilación y permeabilidad de la vía aérea” Incidencia de falla: 0.16 %
- 36. REANIMACIÓN EN EL EMBARAZO ALGORITMOS EN VÍA AÉREA
- 38. Emergencia Urgencia Diferible Inmediata Prioridad en el manejo de la vía aérea
- 39. Emergencia Urgencia Diferible Inmediata Prioridad en el manejo de la vía aérea
- 40. Emergencia Urgencia Diferible Inmediata Prioridad en el manejo de la vía aérea
- 41. Emergencia Urgencia Diferible Inmediata Prioridad en el manejo de la vía aérea
- 43. GUÍAS DE LA ASA Todos los pacientes - Todas las edades Seguridad, efectividad No: pte no colaborador, otros escenarios (UCI)
- 47. Cancelar cx o preparar pte para intubación despierto Broncoscopio rígido, Combitubo, ventilación jet transtraqueal Valvas diferentes, ML para TET (fb), estilete, intercambiador, fb, retrógrada, a ciegas oral o nasal VAD despierto VAD fallida
- 50. GUÍA BRITÁNICA SOCIEDAD BRITÁNICA DE VAD (DAS) Emergencia Simple, claras, definitivas, fácil de aprender Flujograma. Consenso, experiencia y evidencia 1999, 2000 - 2001-2002
- 53. ESTRUCTURA BÁSICA DAS
- 54. INDUCCIÓN DE ANESTESIA GENERAL DE RUTINA: BNMND Bougie + MacIntosh: Cormack 3 McCoy, valva recta Boullard, fb Estilete luminoso experiencia Limitar # y duración 2, máx 4: NVNI Chandy, fb
- 55. INDUCCIÓN DE SECUENCIA RÁPIDA Aspiración Sellick Preoxigenar máx 3 No > Sch
- 56. INDUCCIÓN FALLIDA Y VENTILACIÓN DIFÍCIL
- 58. GUÍA ITALIANA GRUPO DI STUDIO (SIAARTI) 1998, 2005. Inglés, italiano. Extrahospitalario. Sociedad Italiana de Anestesia, Analgesia, Reanimación y Cuidado Intensivo Extraglóticos
- 59. VAD ANTICIPADA (ITALIANA) Minerva Anestesiológica 2005;71:617‐57 Apertura oral ≤ 30 mm Incisivos superiores prominentes DTM ≤ 60 mm Mallampati 4 Cuello fijo en flexión Grandes masas submandibulares o tejido cicatricial Apertura oral entre 30-35 mm Prognatismo moderado a severo pero que corrige DTM 60-65 mm Mallampati 3 Movilidad del cuello reducida Distancia mento‐ yugular reducida Distensibilidad submandibular reducida SEVERA LÍMITE
- 63. GUÍA CANADIENSE CANADIAN AIRWAY FOCUS GROUP Medline: inglés, 1990-1996, ASA 1990
- 64. EVALUACIÓN DE LA VÍA AÉREA Mayor # predictores posibles
- 65. VAD NO ANTICIPADA ML o Combitubo Bougie McCoy
- 67. RESUMEN
- 68. CONCLUSIONES Ayuda TEMPRANA, despertar paciente VAD anticipada: FB despierto NVNI: ML, crico Escoja alternativa más familiar. No empeñarse en técnica fallida - adelanterarse Generar un algoritmo propio de cada institución,adaptado a sus recursos y necesidades Entrenamiento Evaluación continua de adherencia y resultados
Notas del editor
- No moviento del torax Ruidos respiratorios inadecuados o ausentes Obstruccion severa ala ausculatcion Cianos Distencion gastrica Desaturcion no etco2 Alteraciones hemodinamicas: hiper co2 HTA taquicardia
- La dificultad es proporcional al nemero de factores.
- laringoscopia directa consta de dos (oral y faríngeo) y ejes de la lengua
- Múltiples argumentos teóricos
- Diferentes puntos de corte usados
- Se cree q la extencion del cuello es un factor importante determina si la IOT sera facil o dificil
- The authors undertook a prospective evaluation of a predefined algorithm for unanticipated difficult airway management. Methods: After a 2-month period of training in airway man- agement, 41 anesthesiologists were asked to follow a pre- defined algorithm for management in the case of an unantici- pated difficult airway. Two different scenarios were distinguished: “cannot intubate” and “cannot ventilate.” The gumelastic bougie and the Intubating Laryngeal Mask Airway™ (ILMA™) were proposed as the first and second steps in the case of impossible laryngoscope-assisted tracheal intubation , re- spectively. In the case of impossible ventilation or difficult ventilation, the IMLA was recommended , foll owed by percuta- neous transtracheal jet ventilation. The patient’s details, adher- ence rate to the algorithm, efficacy, and complications of air- way management processes were recorded. Results: Impossible ventilation never occurred during the 18-month study. One hundred cases of unexpected difficult airway were recorded (0.9%) among 11,257 intub ations. Devia- tion from the algorithm was recorded in three cases, and two patients were wakened before any alternative intubation tech- nique attempt. All remaining patients were successfully venti- lated with either the facemask (89 of 95) or the ILMA™ (6 of 95). Six difficult-ventilation patients required the ILMA™ before completion of the first intubation step. Eighty patients were intubated with the gum elastic bougie, and 13 required a blind intubation through the ILMA™. Two patients ventilated with the ILMA™ were never intubated. Conclusion: When applied in accordance with a predefined algorithm, the gum elastic bougie and the ILMA™ are effective to solve most problems occurring during unexpected difficult airway management. Factores asociados a intubac difícil Obesidad Aumento del tamaño de las mamas Maniobra de Sellick Desplazamiento anterior de la laringe Estado edematoso del embarazo Sangrado fácil de las mucosas Dosis bajas de inductores Acción de relajantes musculares Tolerancia a la apnea Riesgo de aspiración Ansiedad del médico Inexperiencia del médico Vol sang y GC aumentan progresiva/ desde 5 sem y max 28 sem y luego dism un poco at term Supino utero comprime cava inf px caida GC y reflejo vasovagal FC aumenta 15-20 Lat/min El volumen plasmático corporal corresponde al 7% del peso. Este volumen aumenta 40% al 50% al final de la gestación. El 50% de este aumento se logra al final del primer trimestre. El volumen de eritrocitos aumenta solo el 30% con respecto al plasma, y por lo tanto el hematocrito disminuye en el 10%. El gasto cardíaco aumenta un 33-50% como consecuencia del aumento del volumen circulante y de la frecuencia cardiaca, que aumenta un 20%. El gasto uterino al final de la gestación alcanza a ser de 800 mL/min, similar al gasto cerebral. Aumenta vol 1200ml end gestac Aumento dimens camaras cardiacas = que vol (IM leve30%, derr peric, grosor VI, leve IP, IT 90%) Durante el TdeP, GC aumenta 10-15% x retrono de 300-500ml de sangre a la circulac central durante ctx Posparto inmediato hay aumento de precarga que aumenta GC y permanece elevado 48 hr Flujo uterino es 10% GC at term (600-700 ml/min) comparado 50ml/min no emb (2%GC) PIA aumenta x utero Dism tono EEI x P4 en musc liso Y cambia curvatura estom x PIA (cardias y esof), dism efectividad de esfinter Riesgo vomito y aspiracion Retardo vacia si opioide o TdeP CONSIDERAR siempre como estomago lleno ALTO RIESGO E ASPIRACIÓN Hiperemia y edema va congestion naso y orofaringe: aumenta sangrado y disminuye visualizac glotis por P4 La correcta P cricoidea es 5 N (apretar puente nasal y duela hasta que confirme posic tubo, excepto vomite y aumente P esof evitar ruptura)
- PRACTICE guidelines are systematically developed rec- ommendations that assist the practitioner and patient in making decisions about health care. These recommen-dations may be adopted, modified, or rejected according to clinical needs and constraints. Practice guidelines are not intended as standards or absolute requirements. The use of practice guidelines cannot guarantee any specific outcome . Practice guide- lines are subject to revision as warranted by the evolu- tion of medical knowledge, technology, and practice. They provide basic recommendations that are supported by analysis of the current literature and by a synthesis of expert opinion, open forum commentary, and clinical feasibility data. North American [5, 6], French [7], Canadian [8] and Italian This revision includes data published since the “Prac- tice Guidelines for Management of the Difficult Airway” were adopted by the American Society of Anesthesiol - gists in 1992; it also includes data and recommendations for a wider range of management techniques than was previously addressed.
- Niño, est ment, no coopera 10 miembros PRACTICE guidelines are systematically developed rec- ommendations that assist the practitioner and patient in making decisions about health care. These recommen-dations may be adopted, modified, or rejected according to clinical needs and constraints. Practice guidelines are not intended as standards or absolute requirements. The use of practice guidelines cannot guarantee any specific outcome . Practice guide- lines are subject to revision as warranted by the evolu- tion of medical knowledge, technology, and practice. They provide basic recommendations that are supported by analysis of the current literature and by a synthesis of expert opinion, open forum commentary, and clinical feasibility data. This revision includes data published since the “Prac- tice Guidelines for Management of the Difficult Airway” were adopted by the American Society of Anesthesiol - gists in 1992; it also includes data and recommendations for a wider range of management techniques than was previously addressed.
- Supportive: There is sufficient quantitative information from adequately designed studies to describe a statis- tically significant relationship (P 0.01) between a clinical intervention and a clinical outcome, using meta-analysis. Suggestive: There is enough information from case re- ports and descriptive studies to provide a directional assessment of the relationship between a clinical in- tervention and a clinical outcome. This type of quali- tative information does not permit a statistical assess- ment of significance. Equivocal: Qualitative data have not provided a clear direction for clinical outcomes related to a clinical intervention, and (1) there is insufficient quantitative information, or (2) aggregated comparative studies have found no quantitatively significant differences among groups or conditions. The following terms describe the lack of available scientific evidence in the literature. Inconclusive: Published studies are available, but they cannot be used to assess the relationship between a clinical intervention and a clinical outcome because the studies either do not meet predefined criteria for content, as defined in the “Focus” of these Guidelines, or do not provide a clear causal interpretation of findings because of research design or analytic concerns. Insufficient: There are too few published studies to investigate a relationship between a clinical interven- tion and clinical outcome. Silent: No studies that address a relationship of interest were found in the available published literature. The following terms describe survey responses from the consultants for any specified issue. Responses are assigned a numeric value of agree 1, undecided 0, or disagree 1. The average weighted response represents the mean value for each survey item. Agree: The average weighted response must be equal to or greater than 0.30 (on a scale of 1to1)to indicate agreement. Equivocal: The average weighted response must be be- tween 0.30 and 0.30 (on a scale of 1to1)to indicate an equivocal response. Incidencia de intubación fallida 8-10 veces mas que la población general. (1 /250 – 2130) Furthermore, the incidence of fatal failed intubation is 13 times higher in the obstetrical population (48). Malllampati sube 1 ó 2 grados Definición de Vía Aérea Difícil: Vía aérea difícil: Situación clínica en la cual un anestesiólogo entrenado experimenta dificultad con la ventilación con máscara, dificultad para la intubación o ambas. Ventilaci ón con máscara difícil: Debido a inadecuado sello, fuga de gas o resistencia al flujo de aire. Dificil sat > 90 con fio2 100 y vpp Laringoscopia difícil: Imposibilidad de visualizar una porción de las cuerdas vocales después de múltiples intentos de laringoscopia convencional. Intubación difícil: Multiples intentos en presencia o ausencia de patología traqueal. > 3 INTENTOS o > 10 min Intubación fallida: Falla luego de múltiples intentos [3]. The results of this survey give an overall 5-year incidence of failed tracheal intubation in obstetrics of 1 : 238. This is not significantly different from the incidence of 1 : 249 in the preceding 6 years in the South-West Thames region [8], or from that in other previous reports, in which the incidence has ranged variously between 1 : 250 [7], 1 : 280 [1], 1 : 300 [5] and 1 : 750 [6]. There has been no significant change in the incidence of failed tracheal intubation over the 11 years of our survey. This steady incidence contrasts with that found by Hawthorne et al. [7], who reported an increased inci- dence, albeit not significant, from 1 : 300 in 1984 to 1 : 250 in 1994 . Hawthorne et al. (8), the incidence of failed intuba-tion in the obstetric population is 0.4%—approxi- mately 10 times more frequent than in the general surgical patient population. The number of failed intubations has not decreased over the last 10 years.
- EVALUAC DE LA VIA AEREA Historia y Examen Físico Métodos adicionales incisivos superiores 2. Relación de los incisivos maxilares y mandibulares: protrus mand yo 3. Apertura Oral. 4. Visión de la Úvula (Mallampati > 3): vision de la uvula 5. Forma del paladar. 6. Distensibilidad del espacio mandibular. 7. DTM. 8. Tamaño del cuello. 9. Rangos de movimiento del cuello.
- • Tener un plan claro de manejo basado en preferencias y habilidades de anestesiólogo. Pedir ayuda SIEMPRE The literature suggests that either traditional preoxy-genati on (3 or more minutes of tidal volume ventilation) or fast-track preoxygenation (i.e., four maximal breaths in 30 s) is effective in delaying arterial desaturation The literature supports the efficacy of supplemental oxygen in reducing hypoxemia after extubation of the trachea. 1. Inform the patient (or responsible person) of the special risks and procedures pertaining to manage- ment of the difficult airway. 2. Ascertain that there is at least one additional individ- ual who is immediately available to serve as an assis-tant in difficult airway management. 3. Administer face mask preoxygenation before initiat-ing management of the difficult airway. The uncoop-erative or pediatric patient may impede opportunities for preoxygenation. 4. Actively pursue opportunities to deliver supplemen- tal oxygen throughout the process of difficult airway management . Opportunities for supplemental oxy- gen administration include (but are not limited to) oxygen delivery by nasal cannulae, face mask, laryn- geal mask airway (LMA), insufflation, or jet ventilation during intubation attempts; and oxygen delivery by face mask, blow-by, or nasal cannulae after extuba- tion of the trachea. Recommendations. The anesthesiologist should havea preformulated strategy for intubation of the difficult airway. The algorithm shown in figure 1 is a strategy recommended by the Task Force. This strategy will de- pend, in part, on the anticipated surgery, the condition of the patient, and the skills and preferences of the anesthesiologist. The strategy for intubation of the difficult airway should include 1. An assessment of the likelihood and anticipated clin- ical impact of four basic problems that may occur alone or in combination: a. difficult ventilation b. difficult intubation c. difficulty with patient cooperation or consent d. difficult tracheostomy 2. A consideration of the relative clinical merits and feasibility of three basic management choices:
- Considere otras opciones= cirugia con MF o LMA, o local o regional Acceso invasivo= crico o traqueo quirurgica o percutanea Alternativas para la intubacion= Diferentes valvas, ILMA, estilete, fibro, retrograda, int. A ciegas Ventilacion no invasiva de emrgencia= jet, combitubo, broscoscopio rigido No intubacion, no ventilacion con mascara facial= LMA, combitubo,, jet, brocoscopio rigido Inadequate face mask ventilation after induction—cannot intu- bate: (1) The laryngeal mask airway for emergency ventilation re- duces airway-related adverse outcomes. (2) A rigid bronchoscope for difficult airway management re- duces airway-related adverse outcomes. (3) The esophageal tracheal Combitube (Kendall-Sheridan Cath- eter Corp., Argyle, NY) for difficult airway management reduces airway-related adverse outcomes. (4) Transtracheal jet ventilation reduces airway-related adverse outcomes.
- ELECT: DESPERTAR O2 ML RESCATE DESPIERTO VAD ANTICIPADA
- Multiples intentos: laringosc dificil e intubac dif, no # intentos Intento de intubación óptimo Endoscopista experimentando Ausencia de tono muscular Óptima posición de olfateo Óptima presión laríngea externa Cambiar el tipo de hoja del laringoscopio una vez Cambiar el tamaño de la hoja del laringoscopio una vez
- In the UK there are no national guidelines for management of unanticipated difficult intubation in the non-obstetric patient. The Royal College of Anaesthetists has encouraged individual departments to display national guidelines for management of a number of emergencies. In the case of failed intubation and ventilation they suggest that guidelines are developed locally. However, general concern has been expressed about the quality of local guidelines [13, 14]. The Difficult Airway Society (DAS) has developed guidelines for management of the unanticipated difficult intubation in an adult non-obstetric patient. The purpose of this article is to present these guidelines, to justify the choice of techniques, and to discuss alternative management strategies . Paediatric and obstetric patients, and patients with upper airway obstruction, are excluded. Methods The need for airway guidelines was first discussed at the Annual Scientific Meeting of DAS in 1999 . The following year, members of DAS considered a structured approach to airway guidelines and initiated development of such guidelines for the management of unanticipated difficult intubation. The aim was to produce simple, clear and defi nitive guidelines, similar in structure to those of the Advanced Life Support groups. Such guidelines could be used in training drills and could be followed easily in an emergency situation. Definitive guidelines imply the use of recommended techniques at every stage. These tech- niques must be of proven value and relatively easy to learn. A prototype flow-chart was presented at the DAS Annual Scientific Meeting in November 2000. There was debate and criticism, and constructive suggestions were received at the meeting and subsequently by electronic mail. The DAS executive committee examined the flow- charts in detail at several meetings. Development was based on evidence, experience and consensus. The published literature on difficult and failed tracheal intu- bation was reviewed with extensive Medline searches and use of personal bibliographies. Advice was sought from members who had particular expertise or knowledge. Revised flow-charts were presented at the DAS Annual Scientific Meetings in November 2001 and 2002. There was overwhelming support for the concept and content of the flow-charts. A late version of the paper was sent for comments to 27 DAS members who had been partic- ularly involved in the guidelines discussions. Their comments were considered during preparation of the final version.
- The Difficult Airway Society (DAS) has developed guidelines for management of the unanticipated difficult tracheal intubation in the non-obstetric adult patient without upper airway obstruction. These guidelines have been developed by consensus and are based on evidence and experience . We have produced flow-charts for three scenarios: routine induction; rapid sequence induction; and failed intubation, increasing hypoxaemia and difficult ventilation in the paralysed, anaesthetised patient. The flow-charts are simple , clear and definitive. They can be fully implemented only when the necessary equipment and training are available. The guidelines received overwhelming support from the membership of the DAS. Disclaimer: It is not intended that these guidelines should constitute a minimum standard of practice, nor are they to be regarded as a substitute for good clinical judgement .
- These guidelines are concerned primarily with diffi- culty with tracheal intubation when the larynx cannot be seen with conventional direct laryngoscopy. Even when the larynx can be visualised, it is sometimes difficult to pass the tracheal tube. Use of opti mum shape of the tracheal tube, with [15–19] or without [20] a stylet, or passage of an introducer (‘bougie’) under vision (‘visual bougie’ technique) with subsequent ‘railroading’ of the tube into the trachea, are recommended [2 1]. The Difficult Airway Society guidelines The essence of the DAS guidelines for management of unanticipated difficult tracheal intubation is a series of flow-charts. They should be used in conjunction with this paper. The DAS flow-charts are based on a series of plans. The philosophy of having a series of plans is well established in airway management as no single technique is always effective [22, 23]. Effective airway management requires careful planning so that back up plans (plan B, C, D) can be executed when the primary technique (plan A) fails. This philosophy forms the basis of the DAS guidelines. It is hoped that anaesthetists will always make back up plans before performing primary techniques so that adequate expertise, equipment and assistance are available. Two other principles are particularly important. Main- tenance of oxygenation takes priority over everything else during the execution of each plan. Anaesthetists should seek the best assistance available as soon as difficulty with laryngoscopy is experienced. Not all these plans are appropriate to every possible scenario (vide infra). The outcome of each plan determines progress to subsequent plans. In some situations, progress depends upon clinical factors, such as the best view of the larynx. Subdivision [24] of the Cormack & Lehane [25] grade 3 into 3a (epiglottis can be lifted) and 3b (epiglottis cannot be lifted from the posterior pharyngeal wall) has a significant effect on the success of the introducer (bougie) [24] and fibreoptic techniques [26]. It was not possible to develop a single detailed flow- chart to cover all clinical scenarios. Detailed flow-charts have therefore been developed for each of the following: 1 Unanticipated difficult tracheal intubation – during routine induction of anaesthesia in an adult patient. 2 Unanticipated difficult tracheal intubation – during rapid sequence induction of anaesthesia (with succinyl- choline) in a non-obstetric patient. 3 Failed intubation, increasing hypoxaemia, and difficult ventilation in the paralysed, anaesthetised patient, the ‘can’t intubate, can’t ventilate’ situation. The principal points of these plans are discussed in more detail. Practical details of some techniques are outlined, but full descriptions should be sought in the references and textbooks. The techniques should be practised under supervision in elective situations, where appropriate, and in manikins.
- Fig. 1. This contains the plans and core techniques, and shows the possible outcomes. The plans are labelled A–D: Plan A Initial tracheal intubation plan. Plan B Secondary tracheal intubation plan, when Plan A has failed. Plan C Maintenance of oxygenation and ventilation, postponement of surgery, and awakening the patient, when earlier plans fail. Plan D Rescue techniques for ‘can’t intubate, can’t ventilate’ (CICV) situation.
- Inducc de anestesia general de rutina Scenario 1: Unanticipated difficult tracheal intubation – during routine induction of anaesthesia in an adult patient (Fig. 2) This is the clinical scenario of difficult intubation in an adult patient after induction of general anaesthesia and muscle paralysis, usually with a non-depolarising neuromuscular blocking drug. Plan A: Initial tracheal intubation plan The first attempt at direct laryngoscopy should always be performed in optimal conditions after ensuring adequate muscle relaxation and appropriate position of the head and neck (normally the ‘sniffing’ position of head extension and neck flexion) [27]. Use of optimum external laryngeal manipulation (OELM) [28–32] or BURP ( backward, upward, and rightward pressure on the thy roi d cartilage) [33–35], if required, applied with the anaesthetist’s right hand, should be an integral part of this first attempt [27]. If, despite these measures, there is still a grade 3 or 4 [25] view, then alternative techniques will be needed. These techniques include use of an introducer (‘gum elastic bougie’) [21] and ⁄ or a different laryngoscope . Alternative direct laryngo- scopes of proven value include the McCoy [36–40] and straight [41 , 42] laryngoscopes. The choice of technique depends upon the experience of the anaes- thetist with a particular technique . Oxygenation is maintained with mask ventilation between intubation attempts. The Eschmann tracheal tube introducer (‘gum elastic bougie’) was designed for multiple use and was marketed in the UK in the early 1970s [43]. It differs from previous introducers in its greater length (60 cm), angled tip and the combination of flexibility and malleability . It is i nexpensiv e and readily available and the technique combines simplicity of operation with a high success rate. It is passed blindly into the trachea when the laryngeal inlet is not visible. The most widely used technique in the UK is the combination of the multiple-use bougie (introducer) with the Macintosh laryngoscope [44]. 3 [45] There is evidence that the bougie is more effective than the stylet when the best view of the larynx is grade . The bougie technique should be used in an optimal way. The Macintosh laryngoscope is left in the mouth and attempts are made to insert the bougie blindly into the trachea. It is important to maximise the chance of the bougie entering the trachea. The anaesthetist will not see the bougie entering the larynx when the laryngoscopy view is grade 3 or 4. Therefore it is important to be able to recognise whether the bougie is in the trachea or the oesophagus. Clicks can often be felt by the anaesthetist when the bougie is passed into the trachea [46–48]. These are caused by the tip of the bougie hitting the tracheal cartilages. Clicks are more likely to be elicited if the distal end of the bougie is bent into a curve of about 60 grados [49]. If clicks are present, proceed with intubation by passing (‘railroading’) the tube over the bougie (vide infra). Clicks will not be present if the bougie goes down the centre of the tracheal lumen or is in the oesophagus. If clicks are not elicited, the bougie should be advanced gently to a maximum distance of 45 cm. If distal hold-up is sensed as slight resistance to further advancement, indicating that the bougie is held up in the bronchial tree, proceed with intubation [47]. If the patient is not fully paralysed, coughing may indicate the presence o f the bougie in the rachea [46]. If neither clicks, hold-up: tope, R nor coughing are elicited, the bougie is probably in the oesophagus. Remove the bougie and consider another attempt at passing the bougie blindly into the trachea – if the laryngeal view is 3a [47]. nce the bougie is in the trachea, the tracheal tube is railroaded over the bougie. Railroading is facilitated if the laryngoscope is kept in the mouth [50] and the tube is rotated 90 anticlockwise [50, 51]. Use of a small tube [52–54], reinforced tube [55, 56], the tube (Euromedical ILM) supplied with the Intubating Laryngeal Mask [57, 58] and the Parker tube [59] have all facilitated railroading in flexible fibreoptic intubation. By analogy, it is probable that these tube factors will facilitate railroading with the Eschmann introducer. Success rates with the original reusable Eschmann introducer in prospective studies have varied between 94.3% [24], 99.5% [48] and 100% [49]. Optimum results depend on regular use and experience [48]. However, the technique is of limited value when it is not possible to elevate (grade 3b) [24] or visualise (grade 4) [25] the epiglottis. There are concerns that some recently intro- duced single-use disposable introducers are not as effect- ive as and may cause more trauma than the original multiple-use bougie [60–62]. Alternative techniques of laryngoscopy, of proven value, may be used by those experienced in these techniques. In particular there is considerable evidence of the value of the following techniques in experienced hands: d direct use of the flexible fibreoptic laryngoscope [63, 64]; d Bullard-type laryngoscope [65–75]. There are situations in which these techniques can offer unique advantages. The lighted stylet is not a visual tech- nique, but may be successful in experienced hands [76]. Multiple and prolonged attempts at laryngoscopy and tracheal intubation are associated with morbidity [77–81] and mortality [3, 77, 78, 82]. The extent of laryngeal oedema may not become apparent until fibreoptic examination [83] or extubation [ 84]. An essential com-ponent of Plan A is therefore to limit the number and duration of attempts at laryngoscopy in order to prevent trauma and development of a ‘can’t ventilate ’ situation. It is difficult to justify use of the same direct laryngoscope more than twice and the maximum number of laryng- oscope insertions should be limited to four . However, tracheal intubation may be successful when it is per- formed by a more experienced anaesthetist and one such additional attempt is worthwhile [85, 86]. When these attempts at tracheal intubation have been unsuccessful, Plan B should be implemented. Plan B: Secondary tracheal intubation plan A different approach is required when direct laryngoscopy has failed. Alternative techniques can allow continuous ventilation and oxygenation both during and between intubation attempts. This is best achieved by using a ‘dedicated airway device’, defined as ‘an upper airway device which maintains airway patency while facilitating tracheal intubation’ [87]. Although the classic laryngeal mask airway (LMA ) has been recommended as a ventilation and intubation device in patients with a difficult airway [88], it was not designed as a conduit for tracheal intubation and has clear limitations when used for his purpose (vide infra). Any other supraglottic airway device could be used, but the intubating laryngeal mask (ILMATM) [89, 90] was designed specifically to facilitate tracheal intubation while maintaining ventilation. Each of these devices has advantages and disadvantages. ILMATM for secondary tracheal intubation: Numerous reports have confirmed the effectiveness of the ILMATM for both ventilation and blind intubation in patients without airway difficulties [89, 91–98]. The overall intubation success rate in 1100 patients in these studies was 95.7% [90]. Fur ther studies have confirmed its value in management of patients with known or anticipated difficult tracheal intubation [99–107]. The ILMATM has also proved to be a useful device in the management of unanticipated difficult intubation. In one study, blind intubation was performed in 20 out of 23 patients with a 75% success rate at the first attempt (10% required two or three attempts and 5% required four attempts) and 100% overall success rate [104]. Fibreoptic guided intubation was successful at the first attempt in the remaining three patients. Although high success rates can be achieved with a blind technique, several attempts may be required and the incidence of oesophageal intubation can be up to 5% [108, 109]. Transillumination techniques may improve first-attempt success rates [110] and certainly reduce the number of manoeuvres required, the incidence of oesophageal intubation and the time required to achieve intubation [111, 112]. However, intubation under vision through the ILMATM using a flexible fibreoptic laryng- oscope has rea l advantages. The first-attempt [104] and overall [113] success rates are higher than blind tech- niques, and it nearly always succeeds when blind intubation fails [103]. The techniques of insertion and intubation through the ILMATM differ in many respects from the classic LMATM, and training and practice are essential if it is to be used to achieve a high success rate and minimise trauma in the unanticipated difficult tracheal intubation. A learning curve of about 20 insertions has been described [95, 114]. The manufacturer’s instruction manual describes the insertion and intubation techniques, the adjustments necessary for ideal positioning of the device and an approach to problem-solving [115]. The ‘Chandy man- oeuvre’ (alignment of the internal aperture of ILMATM and the glottic opening by finding the degree of sagittal rotation which produces optimal ventilation, and then applying a slight anterior lift with the ILMATM handle ) facilitates correct positioning and blind intubation through the ILMATM and has been shown to reduce the number of intubation attempts [104]. Use of the dedica-ted silicone tracheal tube is strongly recommended [115]. The fibrescope can be used to visualise the ‘Epiglottic Elevator Bar’ lifting the epiglottis and observe passage of the tracheal tube through the glottis [90, 116] or it can be passed into the trachea after glottic visualisation and then used to railroad the tube [104]. We prefer the latter technique. The lubricated silicone tracheal tube is first inserted into the shaft of the ILMATM until its tip reaches the mask aperture (indicated by the transverse line on the tube). The fibrescope is then inserted through the tracheal tube so that its tip is just within the tip of the tube. The tube and fibrescope are then advanced together for about 1.5 cm so that the ‘Epiglottic Elevator Bar’ is seen to elevate the epiglottis. Once the tip of the tube is in the larynx, the fibrescope is advanced into the trachea and the tube is then railroaded over it [90, 104]. Finally, the position of the tube is checked with the fibrescope during withdrawal. Oxygen and anaesthetic gases can be deliv- ered continuously if a self-sealing bronchoscope connec- tor is attached between the 15-mm tracheal tube connector and the anaesthetic breathing system [104 ]. Ventilation is maximised by using a wide tracheal tube with a narrow fibrescope [117]. The ILMATM should be removed when tracheal intubation has been verified and the tracheal tube secured [ 118, 119]. Classic LMATM for secondary tracheal intubation: Fibre- optic tracheal intubation through the classic LMATM (the role of the single-use LMATM in management of the difficult airway patient has not been established) should be considered when an ILMATM is not available. Although Heath [120] reported a 93% success rate for blind intubation through the LMATM (in the absence of cricoid pressure), others have achieved much lower success rates [121, 122] and blind intubation cannot be recommended. uccess rates of 90–100% (depending on technique, equipment, number of attempts allowed and experience f user) can be achieved with fibreoptic intubation through the classic LMATM [113, 123, 124]. The limitations of the classic LMATM as a conduit for intubation are well known [125, 126] and include the following: d The LMATM tube connector is narrow and will only allow a 6 mm (ID) tracheal tube through a size 3 or 4 LMATM and 7 mm (ID) through a size 5 lma TM d The LMATM tube is so long that the cuff of an uncut normal tracheal tube (26–27 cm) may lie between the vocal cords so that it is ineffective and potentially traumatic. A long flexometallic tube [127], nasal RAE [128] or a microlaryngeal tube [129–131] is recommended. d The mask aperture bars may obstruct the passage of the tracheal tube; d Manipulation requires head and neck movement and ⁄ or finger insertion, both of which may worsen difficulties. Difficulties may be encountered during subsequent removal of the LMATM. The LMATM may be left in situ if its presence does not interfere with surgical access. Techniques of LMATM removal without dislodging the tracheal tube have been described, but they may fail and expose the patient to avoidable danger [132]. The problems mentioned above can be avoided by using a two-stage technique with a flexible fibreoptic laryngoscope and an Aintree Intubation Catheter [87, 133, 134]. Whatever technique of tracheal intubation through a ‘dedicated airway’ is used, the vocal cords should be open and non-reactive before attempting to advance the fibrescope or tracheal tube into the trachea. If two attempts at the secondary tracheal intubation technique fail , surgery should be postponed and the patient awakened, i.e. Plan C should be implemented. Plan C: Maintenance of oxygenation and ventilation, postponement of surgery and awakening the patient – if Plans A and B have failed If Plan B (secondary tracheal intubation technique) fails, it remains important to avoid trauma to the airway and to maintain ventilation and oxygenation with the dedicated airway device. Elective surgery should be cancelled and the airway device should be removed only after muscle relaxation has been reversed, sponta- neous ventilation is adequate, and the patient is awake. An alternative plan for anaesthesia can then be made. Although it may be possible to perform surgery under regional anaesthesia, the safest plan is to secure the airway with the patient awake [ 135]. If adequate ventilation and oxygenation cannot be achieved with the dedicated airway device, ventilation should be performed using a face mask with or without an oral or nasal airway. If ventilation is impossible and serious hypoxaemia is developing, then Plan D (Rescue techniques for ‘can’t intubate, can’t ventilate’ situation) should be implemen- ted without delay (vide infra).
- Inducc de secuenc fast Scenario 2: Unanticipated difficult tracheal intubation – during rapid sequence induction of anaesthesia (with succinylcholine) in a non-obstetric patient (Fig. 3) Plan A: Initial tracheal intubation plan In scenario 2, in contrast to scenario 1 , there is an increased likelihood of regurgitation or vomiting, with a consequent risk of p ulmonary aspiration. The change in management involves the use o f pre-oxygenation and the application of cricoid pressure. It is particularly important to use a pre-oxygenation technique which maximises oxygen stores [136]. Cricoid pressure has played an important role in the prevention of pulmonary aspiration since its introduc-tion by Sellic k [137]. It is an integral part of the flow- chart for the patient having rapid sequence induction. However, it can impair insertion of the laryngoscope [138], passage of an introducer [139] and can cause airway obstruction [140–146]. A force of 30 N provides good airway protection, while minimising the risk of airway obstruction [147], but is not well tolerated by the conscious patient. Cricoid pressure should be applied with an initial force of 10 N when the patient is awake, increasing to 30 N as consciousness is lost [139]. The force should be reduced, with suction at hand, if it impedes laryngoscopy or causes airway obstruction. The principles of optimising the initial tracheal intu bation technique, and use of the Eschmann introducer and alternative direct laryngoscopes, are the same as in Plan A in the elective patient. If intubation fails despite a maximum of three attempts, a failed intubation plan with th e aim of maintaining oxygenation and awakening the patient (Plan C) is initiated immediately. Further doses of succinylcholine should not be given. Plan C: Maintenance of oxygenation and ventilation and postponement of surgery, if possible Plan B is omitted from airway management of the patient having rapid sequence induction for two reasons. The risk of regurgitation or vomiting is greater than in the elective patient, so that the risk of aspiration during further attempts at tracheal intubation is higher. The short duration of succinylcholine increases the risk of laryngo- spasm and difficulty with laryngoscopy during recovery of neuromuscular function, so that further tracheal intuba- tion attempts increase the risk to the patient. When initial attempts at tracheal intubation in this scenario fail, the safest plan in most patients is to postpone surgery and awaken the patient. Plan C of this scenario contains two subsidiary scenarios, in which the urgency of proceeding with surgery differs. A risk-benefit assessment balances the risks of delaying surgery against the risk of proceeding with a suboptimal airway. If it is essential to proceed with surgery, the traditional technique has been to continue with a face mask and oral airway, maintaining cricoid pressure [148, 149]. Continuation of anaesthesia with a classic LMA is now an established technique [150, 151], although not always effective [152] or accepted [149, 153] (effect of cricoid pressure on LMATM insertion – vide infra). If it proves difficult to ventilate the lungs as a consequence of gas leakage past the cuff of the lassic LMATM, use of the ProSeal LMATM should be considered. The ProSeal LMATM forms a better seal [154– 160] than the classic LMATM and provides improved protection against aspiration [161–164]. The potential advantages of the ProSeal LMATM have to be offset against increased complexity of insertion [157, 160, 165, 166] (not a problem when a precise technique [166] and the insertion tool are used [156, 167]). The risk (about 5%) of airway obstruction [168] may be lower than that with the classic LMATM [158]. Airway obstruction may be overcome by reinsertion [169], use of a smaller size [170], withdrawal of air from the cuff [167, 170] and ⁄ or moving the head and neck into the sniffing position [167]. However, poor seal and airway obstruction may be significant problems in some obese patients [171]. Wherever possible the aim should be to postpone surgery and awaken the patient. Maintenance of venti- lation and oxygenation with a face mask is a conventional technique. This may include the one- or two-person technique and the use of an oral or nasal airway. A narrow, soft, lubricated nasopharyngeal airway may be inserted gently [172, 173] if this can be done without trauma [174, 175]. It may be necessary to reduce cricoid force in order to achieve satisfactory ventilation. If satisfactory oxygenation (e.g. SpO2 > 90% with FiO2 1.0 ) cannot be achieved with a face mask, the LMATM should be used. Cricoid force impedes positioning of [176–180] and ventilation through [180–183] the LMATM. It may be necessary to reduce cricoid force during LMATM insertion when it is used in an emergency [177, 178]. If ventilation is impossible and serious hypoxaemia is developing, then Plan D (Rescue techniques for ‘can’t intubate, can’t ventilate’ situation) should be implemen- ted without delay.
- Intubac fallida y ventilac difícil Scenario 3: Failed intubation, increasing hypoxaemia and difficult ventilation in the paralysed anaesthetised patient Plan D: Rescue techniques for ‘can’t intubate, can’t ventilate’ situation (Fig. 4) This scenario may develop rapidly, but often occurs after repeated unsuccessful attempts at intubation in scenarios 1 and 2, where a ‘can ventilate’ situation develops into a ‘can’t intubate, can’t ventilate’ (CICV) situation [77, 78, 81, 82]. It is probable that most patients who suffer hypoxic damage pass through a CICV stage [77, 184]. In situations where mask ventilation fails to oxygenate the patient, the upper airway is normally sufficiently patent to allow gas to escape upwards [185–189]. This has an important bearing on the efficacy of different airway rescue techniques (vide infra). Before resorting to invasive rescue techniques, it is essential that a maximum effort has been made to achieve ventilation and oxygenation with non-invasive tech- niques, such as optimum mask ventilation and the LMATM. Other supraglottic airway devices, particularly the Combitube TM, have been used in the CICV situation. Satisfactory placement of the Combitube is not always possible, even when inserted with a laryngoscope [190]. When properly positioned, it allows ventilation with a higher seal pressure than the classic LMATM, protects against regurgitation [191], and allows subsequent attempts [192] at intubation while the inflated oeso- phageal cuff maintains airway protection. Although there have been failures [193, 194], the Combitube has been used successfully in the difficult intubation [191, 195] and the CICV situation [196–199], including failure with the LMATM [200]. Adjustment of cuff pressure may be necessary [201]. The Combitube is a large and bulky device, and there have been some reports of oesophageal damage with the original product [202–205], but the risk should be lower with the SA (Small Adult) size [192, 206]. The decision to use the Combitube will depend on availability, experience and the clinical situation. The risks of an invasive rescue technique must be constantly weighed against the risks of hypoxic brain damage or death [207]. Rapid development of severe hypoxaemia, particularly associated with bradycardia, is an indication for imminent intervention with an invasive technique. Once the decision to perform an invasive technique is made, it is essential to use an effective technique. Rapid reoxygenation is now necessary, and this is best achieved with a combination of an invasive airway device and a ventilation technique which is capable of reliably delivering a large minute volume with an FiO2 of 1.0. Many cricothyroidotomy techniques have been criticised because they are not capable of providing effective ventilation [4, 208–213]. Classical emergency surgical tracheostomy involves incision through skin and platysma, division of the isthmus of the thyroid gland, haemostasis, incision of tracheal cartilage, and insertion of a cuffed tracheostomy tube [214]. Emergency tracheostomy can be very difficult and have serious complications [215–217]. A few surgeons may succeed in 3 min [85, 218], but most will take longer [217, 219]. Delay in completion of tracheostomy in this situation results in death of the patient [77, 219–224]. There are a few case reports of successful use of percutaneous tracheostomy techniques in the failed intubation [225–227] and CICV situation [228]. How-ever, percutaneous tracheostomy techniques include a number of steps and can take time. The anaesthetist must be prepared to use invasive techniques to secure the airway via the cricothyroid membrane. Success depends on understanding the anat- omy of the cricothyroid membrane [229–231] and of the factors which determine efficacy of ventilation with different airway devices. Invasive airway devices which are frequently recom-mended include: d cuffed tracheal or tracheostomy tubes; d narrow (4–6 mm ID) uncuffed tubes; d cannulae. These must be matched to the ventilation technique in order to provide a system which can deliver a large minute volume. When a cuffed tube is used, a low- pressure ventilation system is satisfactory. When a 4-mm (ID) uncuffed tube is used, successful ventilation is less certain [232–235]. The ‘inflated’ gas may enter the lungs or flow out through the upper airway. Factors which promote entry of gas into the lungs include high resistance in the upper airway, high lung compliance, high flow rate and long inflation time. The limitations of uncuffed tubes in the CICV situation are well summarised by Walls [236]. When a cannula is used, a high-pressure ventilation source is necessary. This system is discussed clearly by Dworkin [237]. All current airway guidelines [5–8,12] recommend management of the CICV situation using: cannula cricothyroidotomy with percutaneous transtra-cheal jet ventilation (TTJV) or; d surgical cricothyroidotomy. They remain the standard techniques. Cannula cricothyroidotomy: Cannula cricothyroidotomy involves the combination of insertion of a cannula through the cricothyroid membrane with high-pressure ventilation. It can provide effective ventilation [4, 209, 238–241], although low success rates have been repor- ted [242]. We recommend use of kink-resistant cannulae because standard intravenous cannulae are easily kinked [243–245]. The technique is summarised in the flow-chart and is described in detail by Benumof [246] and Stewart [247]. Verification of correct cannula placement by aspiration of air into a large syringe, before the use of high-pressure ventilation, is essential. Subsequent dislodgement of the cannula must be prevented. A high-pressure source is needed to achieve effective ventilation through a cannula. The oxygen flush systems of most modern anaesthesia machines do not provide sufficient pressure [211, 248, 249] and an adjustable high-pressure device (driven by gas pipeline pressure) with a Luer Lock connection is recommended. Baro-trauma [188, 238, 250, 251] is less likely if an initial inflation pressure of less than 4 kPa (55 psi) is used [213, 251, 252]. Some have recommended insertion of a second cannula to facilitate exhalation [185, 186, 253]. However, the driving pressure for exhalation is relat- ively low and use of a second cannula is not a reliable means of relieving high airway pressure [254, 255]. Initial high-pressure ventilation should be performed particularly cautiously. It is important to keep the upper airway as open as possible and to verify deflation of the lungs and exhalation through the upper airway. If an LMA has been used, it should be kept in place to facilitate exhalation. Surgical cricothyroidotomy: Surgical (‘stab’) cricothyroid- otomy can allow rapid restoration of ventilation and oxygenation in the CICV situation [77, 242, 256–260] and is included in ATLS and military [261] training. Anaesthetic deaths could be prevented by appropriate use of surgical cricothyroidotomy [207]. Emergency crico- thyroidotomy can result in serious complications [216, 262], although these are infrequent when staff are well trained [263–267]. The technique uses low-pressure ventilation through a cuffed tube in the trachea. A simplified cricothyroidotomy technique can be performed in 30 s [268–270]. This 4-step technique consists of: Step 1 Identification of the cricothyroid membrane. Step 2 Horizontal stab incision (No. 20 scalpel) through skin and membrane. Step 3 Caudal traction on the cricoid membrane with a tracheal hook. Step 4 Intubation of the trachea. The ATLS cricothyroidotomy technique includes blunt dilation of the incision made in step 2. It is important to avoid endobronchial intubation [21] when a tracheal tube is used. Cricothyroidotomy is sometimes particularly difficult in the obese patient. Insertion of the tube can be facilitated by passage of an introducer (bougie) through the incision [272] or use of a tracheal retractor [270, 273– 277]. Guidewire techniques of cricothyroidotomy have been developed. Some claim that these can restore the airway as quickly as the standard surgical technique [278], while others have found the guidewire technique to take longer [279], and to be less satisfactory, as a consequence of kinking of the wires [280]. It has recently been shown that the technique can be performed in 40 s after practice in a manikin [281]. The Melker TM guidewire intubation set is now available with a cuffed tube. This technique seems promising but further reports are needed before it can be considered a core rescue technique. Cannula and surgicalcricothyroidotomy each have advantages and disadvantages. Cannula cricothyroidoto- my involves a smaller incision with less risk of bleeding. It may be the technique of choice when dedicated equipent is immediately available and staff are trained in its use. If it cannot be performed rapidly, is ineffective [242, 245, 258] or causes complications [258, 282], surgical cricothyroidotomy should be performed immediately [242, 245, 258, 282]. Surgical cricothyroidotomy is more invasive. It can be performed very rapidly and will allow effective ventilation with low-pressure sources. Invasive airway access is a temporary measure to restore oxygenation. Definitive airway management will follow. This may be a formal tracheostomy, but tracheal intubation will be possible in some patients [257, 283].
- Guidelines for management of the difficult airway have been published recently by North American [5, 6], French [7], Canadian [8] and Italian [9] national societies or groups. A limitation of the American guidelines is the use of flow-charts which allow a wide choice of techniques at each stage. This wide choice makes them less useful for management of airway emergencies than simple and definitive flow-charts such as those in the European [10, 11] or American Heart Association [12] Advanced Life Support guidelines. In the UK there are no national guidelines for management of unanticipated difficult intubation in the non-obstetric patient. The Royal College of Anaesthetists A major impetus for the development of clinical guide-lines was the finding of marked variations in medical practice and the belief that guidelines could be used to improve standards [284–286]. Guidelines have much to offer in the management of infrequent, life-threatening situations [287, 288]. In particular, following the resus-citation guidelines improves outcome [12, 289, 290]. There is evidence that use of airway guidelines has improved airway management in France [291]. Unanticipated difficult intubation will continue to occur. A new approach is needed to ensure optimal management of infrequent airway problems. Medicine has lagged behind the military [292–297] and the airline industry [298–300], which use guidelines and regular practice of drills to train staff to deal with infrequent emergencies. Allnutt states that ‘there is no excuse for poorly designed procedures when human life is at risk’ [301]. Tunstall first described a failed intubation drill [148] for use in obstetric anaesthesia. Although of proven value [302, 303], some components such as the lateral position are no longer widely supported [146, 304–306] and new devices such as the LMATM have changed management [307]. There are now new failed intubation drills in obstetrics [308]. There is a need for definitive national airway guidelines for management of unanticipated difficult intubation in the non-obstetric adult patient [309]. They should be easy to learn and to implement as simple drills [310]. They should include a minimum number of techniques of proven value. They should be based on a practical approach to airway management, using skills which are widely available. The DAS guidelines are designed to fulfil these requirements. Simple, clear and definitive fl ow-charts have been produced to cover three important clinical scenarios. They do not proscribe the use of other techniques by those experienced in their use, provided oxygenation is maintained and airway trauma is prevented. The DAS guidelines have been developed by consensus and are based on experience and evidence. The principles applied are maintenance of oxygenation and prevention of trauma. Maintenance of oxygenation is achieved primarily by using the face mask and LMATM. Prevention of trauma is achieved by limiting the number of attempts at intubation and by using the ILMATM as a dedicated airway to allow oxygenation, while tracheal intubation is achieved under vision with the fibrescope. Controlled studies cannot be performed in unanticipated difficult intubation. The evidence basis of these guidelines best fits the description of expert committee reports, opinions and experience, and is defined as category IV vidence [311]. The DAS recommendations are therefore officially strength D. All DAS recommendations are supported by at least two case reports or series, the strongest evidence available for infrequent emergency situations. We hope that implementation of these guidelines will reduce the incidence of airway trauma and hypoxaemic damage associated with unanticipated difficult intubation and result in better outcomes for our patients. The techniques which have been recommended in these plans should be an integral part of initial and continuing airway training. This can be achieved by acquisition of knowledge in classroom teaching, learning practical skills using manikins in workshops [281], and use in clinical practice, when appropriate [312, 313]. There are equipment implications in these guidelines. All the equipment described should be available for regular practice. A cart containing the equipment should be located no more than a couple of minutes from every location where anaesthesia is administered. Recommen-ded equipment lists will be published on the DAS Web Site (http://www.das.uk.com). We hope that these guidelines will be tested in a clinical environment [314] and further modifications will certainly follow. We seek constructive suggestions. Notes on figures: Figures 2–4 in this paper contain a considerable amount of detail in order to maximise their value for training. Both these and simpler versions will be available from the DAS Web Site (http://www.das.uk. com) in the future. Others may wish to produce different versions for their own purposes.
- In 1998 the Italian Society of Anaesthesia, Analgesia, Resuscitation and Intensive Care (Società Italiana di Anestesia, Analgesia, Rianimazione e Terapia Intensiva, SIAARTI) Difficult Airway Study Group (Gruppo di Studio, GdS) firstly published a Guidelines document, including Italian Recommenda- tions for Adult Difficult Airway,1 followed by a paediatric section published later and sep-arately 2 in cooperation with the Italian Society of Paediatric and Neonatal Anaesthesia (Società di Anestesia e Riani- mazione Neonatale e Pediatrica, SARNePI). These documents and algorythms were pub- lished on the SIAARTI official scientific mag- azine, on the SIAARTI website and were sent to all Italian Anaesthetists too. The English version allowed a widespread diffusion of the document, that led to European Airway Management Society (EAMS) 3 and Society for Airway Management (SAM) 4 awards for the Italian GdS, whose components and activ-ity are illustrated on the SIAARTI webpages and on the recently available official GdS site http://www.vieaereedifficili.org. Five years after the first release, the con- tinuous literature review operated by the GdSSIAARTI, aimed to verify the general princi- ples actuality, the devices technological evo- lution, and the feedback of health-care providers involved in airway management, led to the present Guidelines update. Between the various fields of interest regarding airway management, not only Anaesthesia but all the clinical fields in which the Anaesthetist may be involved as an expert for the difficult airway manage- ment have been considered, including emer- gency and o ut-of-h ospital settings, both for
- 5.1. Severe predicted difficulty - impos- sible intubation According to literature data, all the fol- lowing parameters, being significant the presence of a single parameter, should be considered as highly predictive of diffi- cult or impossible intubation: a) interincisor distance equal or less than 30 mm ( if less than 20 mm, neither laryngo- scopic traditional blades nor the majority of extraglottic devices can be introduced into the mouth); b) large prominence of superior teeth above inferior teeth, especially if not corrigi- ble with jaw-thrust manoeuvre; c) mental-thyroidal distance equal or less than 60 mm; d) Mallampati test degree 4, not modified by phonation; e) fixed neck in flexion; f) scar tissue or large post-i rradiatio n scars of tongue and soft tissues and large sub- mandibular masses. 5.2. Borderline predicted intubation dif-ficulty All the following are considered signs of predictable or certain difficult intubation whenever differently associated: a) Interincis or distance between 30 and 35 mm; b) modest or severe but corrigible prog- natism; c) mental-thyroidal distance between 60 and 65 mm; d) Mallampati test score 3; e) reduced head and neck motility; f) reduced mental-jugular distance; g) reduced submandibular compliance. Preoperatory evaluation, planning of diffi cult airways management strategies and the description of all observed parameters rep- resent a fundamental part of anaesthesiolog-
- electivo a) call for help immediately; b) define the grade of laryngoscopic diffi- culty and decide further steps on this obser- vation too; c) immediate withdrawal in case of diffi- culty usually considered “not to be managed” with some suggested alternative device; d) limit the number of attempts, where even the simple laryngoscopy without an attempted intubation should be considered as an “attempt”; e) oxygenation between each attempt; f) immediate withdrawal after the third failed attempt performed by an experienced anaesthetist (i.e. the fourth one if the first attempt was performed by a relatively inex- perienced anaesthetist) and return to spon-taneous breath and consciousness; g) if mask ventilation becomes ineffective, despite an oral or nasal airway or the three- hand bag mask ventilation, replace the face mask with a LMA or other extraglottic device considered equivalent in the operator’s expe rience; h) early oxygenate through a cricothyro- tomy, if required; the following step is the choice between different options: to postpone surgery, to switch to a loco-regional anaesthesia tech- nique, to perform an awake fiberoptic intu- bation , immediate or deferred. urgente 1) Patient’s oxygenation is mandatory and is the absolute priority (B). 2) Before each intubation attempt, it is rec ommended that the Anaesthetist chooses the appropriate pharmacological schema t o allow a quick return to consciousness and sponta- neous breathing (E). 3) It is recommended to refer to the modified Cormack and Lehane grading system (E). 4) It is recommended an immediate with- drawal in case of Grade IV laringoscopy and in case of Grade III-e laryngoscopy, if the oper- ator has inadequate experience (E). 5) It is recommended not to exceed 3 laryn- goscopic attempts, after the first one performed by the unskilled operator, in all laryngoscop- ic visualization grades (E). 6) It is recommended not to perform the 3 attempts with the same technique, but “alter- native” devices and procedures should be employed (E). 7) Re-oxygenation and re-evaluation of ventilability are mandatory before any new laryngoscopic attempt (D). 8) If even the minimal difficulty to correct signs of oxygenation failure occurs, it is not recommended to perform new intubation attempts (D). 9) It is recommended to reach an appro- priate preliminary knowledge of alternative devices suggested for Grade II-e and Grade-III laryngoscopies (E). 10) In case of declared surgical emergency and failed intubation, unavoidable surgery should be performed without tracheal intu bation, even in case of aspiration risk (D). 11) It is recommended to consider the us of LMA or other extraglottic devices (D) early 12) Blind intubation via LMA or othe extraglottic devices is not recommended in emergency settings or after repeated intuba tion attempts (E). 13) It is mandatory to grant the possibilit of fiberoptic intubation in every Anaesthesia Department, both by a property fiberscope o by consult and cooperation with othe Departments in the same Hospital (D). 14) Adequate training in the use of th fibrescope is mandatory for all the personne (C). 15) The GdS states that direct vision tech niques (laryngoscopy, fiberoptic techniques offer greater safety features than the blind techniques, and therefore are recommended (D). 16) The use of the fibrescope in emergency situations is not recommended (E). 17) Experience acquisition on mannequins or in clinically simulated difficulty with all devices and techniques out of the clinical sit- uations is mandatory (D).
- The Italian Society of Anesthesia, Resuscitation, and Intensive Therapy (SIAARTI) published their guidelines about management of the unanticipated and anticipated difficult airway in 1998. 9 Their recommendations for the management of the unanticipated and anticipated difficult airway are summarized within two flow charts. The key question of the former is whether ventilation is possible or not. For the latter, their strategy depends on differentiation between borderline and severe cases. The guidelines also incorporate suggestions for management of the ‘cannot ventilate, cannot intubate’ scenario. Further, t hey recommend awakening the patient and postponing surgery at different steps The French Society of Anaesthesia and Intensive Care7 distinguishes between management of an anticipated difficult airway and management of the unanticipated difficult airway. For the former, they recommend an awake technique, whereas the further steps of the latter are influenced by whether mask venti lation is possible or not. They strongly emphasize the importance of pre-oxygenation. Nati onal programmes for airway training, based on these guidelines, have been set up in France, as is the case in Italy. The recommendation (practice policies) of the Ger man Society of Anaesthesiology and Intensive Care Medicine (DGAI) 6 for airway management have a similar structure to the 2003 ASA guidelines. Their strategy depends on the condition of the patient, the type of surgery, and the skills of the anaesthetist. In addition to recommendations for management of the anticipated and unanticipated difficult airway and the ‘cannot intubate, cannot ventilate’ scenario, they give advice for airway management of cervical spine pathology (preferred usage of fibre-optics and ILMAe ). They also recommend use of these guidelines as a basis of national training programmes.
- Methods: A literature search using key words and filters of English language and English abstracted publications from 1990-96 contained in the Medline, Current Contents and Biological Abstracts databases was carried out. The literature was reviewed and condensed and a series of evidence-based recommendations were evolved. Conclusions: The unanticipated difficult airway occurs with a low but consistent incidence in anaesthesia practice. Difficult direct laryngoscopy occurs in 1.5 - 8.5% of general anaesthetics and difficult intubation occurs with a similar incidence. Failed inubation occurs in 0.13-0.3 % general anaesthetics.. Devices such as the laryngeal mask, lighted stylet and rigid fibreoptic laryngoscopes, in the setting of unanticipated difficult airway, are effective in establishing a patent airway, may reduce morbidity and are occasion- ally lifesaving. Evidence supports their use in this setting as either alternatives to facemask and bag ventilation, when it is inadequate to support oxygenation, or to the direct laryngoscope, when tracheal intubation has failed. Specifically, the laryngeal mask and Combitube™ have proved to be effective in establishing and maintaining a patent airway in "cannot ventilate" situations. The light- ed stylet and Bullard (rigid) fibreoptic scope are effective in many instances where the direct laryngoscope has failed to facilitate tra-cheal intubation. The data also support integration of these devices into strategies to manage difficult airway as the new standard of care. Training programmes should ensure graduate physicians are trained in the use of these alternatives. Continuing medical education courses should allow physicians in practice the opportunity to train with these alternative devices. THE "Practice guidelines for management o the difficult airway" produced by the American Society of Anesthesiologists' Task Force on Management of the Difficul Airway and published in 1990 r epresented a majo advance in the approach to and management of difficul- ties related to airway interventions. 1 Evidence-based rec- ommendations were derived by consensus of the Task Force members and input from the ASA membership following an extensive literature search. Since the publi cation of the guidelines there has been a substantia number of new publications in the field of airway man- agement. As well, there have been both the introduction of new airway devices and a wider dissemination of a number of devices with which there had been limited experience at the time of publication of the guidelines. It was the opinion of the authors that there was value in reviewing the more recent literature as well as the accumulated experience with the new devices, in orde to determine whether previous recommendations might be modified or new recommendations derived The following text is the product of this review. Methodology Canadian anaesthetists with an interest in airway man- agement and education were invited by the lead author to participate in the project. A meeting was held to establish a mandate and set an outline for the project. Draft positions on the various facets of the mandate were generated following completion of a structured search of the literature. Additional meetings were held at which the drafts were reviewed, discussed and revised and consensus reached on the content and the recommendations derived. The final draft document was approved by the members of the authors group. STRUCTURED LITERATURE SEARCH AND GENERA- TION OF RECOMMENDATIONS A structured literature search intended to inform the workings of the project members was carried out. Key words and filters were employed to generate a search of English language and English abstracted publications from 1990-96 contained in the Medline, Current Contents and Biological Abstracts databases. For litera- ture published prior to 1990, the structured search car- ried out by the ASA Task Force was obtained from the ASA and utilized. The new search was expanded beyond the scope of original ASA Task Force search to obtain studies relating to the expanded mandate for this project including the paediatric and obstetrical airway, applications of new drugs and technology and educa- tional issues. A large number of titles retrieved were deleted for lack of relevance. The remaining titles were searched and culled . Only titles including original data were included; excluded were titles relating to animal work and titles with no original data (reviews, editori- als, comments). The reference lists of relevant articles were searched and project members added references from their own files to complete the search. This document summarizes the results of the litera- ture review; the recommendations contained represent the consensus opinion of the project membership regarding the materials reviewed. The data supporting the recommendations were assigned a level of evidence ranking according to the levels established by the Canadian Task Force on the Periodic Health Examination. 2 (Table I) Recommendations were grad- ed according to the level of evidence supporting them. 3 (Table II) la. The difficult airway - a definition of terms Anaesthetists agree that management of the difficult airway is a fundamental part of clinical practice. There is not agreement as to how to define the condition, which results in difficulties gathering data on both the incidence and outcome. As well, commentary or rec- lb. The incidence of difficult airway The incidence of the difficult airway, difficult laryn- goscopy and difficult intubation is not well defined. However, a number of conclusions can be drawn from recently published, large series involving prospective, preoperative airway assessments. 5 “ 1 •(Table IV) First, achieving a poor view (Grade 3/4) during laryn- goscopy is common (2-8%). Experiencing difficulty intubating the trachea, although associated with a poor view, is less common, likely by a factor of 5-10. Failure to intubate the trachea is even more uncom- mon, likely seen one to three times per 1,000 attempts, and again less common than difficult intu-
- Current techniques for predicting difficulty with laryngoscopy and intubation are sensi- tive, non-specific and have a low positive predictive v alue Assessment techniques which utilize multiple characteristics to derive a risk factor tend to be more accurate predictors bation by a factor of 5-10. Finally, being unable to ventilate the lungs with facemask and bag is more uncommon still, now likely occurring 1-3 times per 10,000 attempts. lc. Preoperative assessment of the airway - predic- tion of difficult intubation Mallampati reported a correlation between the visibility of oropharyngeal structures and the degree of difficulty of laryngeal exposure during direct laryngoscopy and concluded that poor visualization could be predicted by a visual assessment of the airway (Table V). 12 Preoperative examination and classification using a three tier grading system was proposed. Samsoon and Young added a further tier, class IV, and observed that among patients in whom laryngoscopy was known to be diffi- cult, class III and class IV assignments predominated. 13 There have since been proposed further modifica- tions of Mallampati's original schema and alternative strategies to assess the airway. 6 ‘’14 “ 20 These have ranged from using simple anatomical descriptors, ranking and summating anatomical factor scores, 10 ‘’15 “ 20 (Table VI) using logistic regression to create predictive scales, 6 and the derivation of a performance index. 21 The dif- ferent strategies share some common characteristics; they have a high sensitivity but low specificity and low positive predictive value with respect to the diagnosis. Additionally, many of the tests have only moderate inter-observer reliability. 22 This may help explain why the tests fail to predict difficult tracheal intubation accurately. Although the majority of strategies implicate airway class as a predictor of difficult intubation, the Mallampati classification used alone is an imprecise mechanism for the preoperative detection of the diffi- cult to intubate patient. The combination of the Mallampati classification with evaluation of other risk criteria improves the specificity and sensitivity of the preoperative assessment. 6 ‘’10 ‘’15 ‘’18 ‘ 21 For example, a high- er likelihood of difficult intubation can be anticipated with Mallampati class IV combined with a receding chin, a short neck or protruding maxillary incisors and , in particular, with a combination of class IV and any two of the above characteristics than with a class IV designation alone. 6 Thus, an assessment strategy which sum mat es the impact of anatomical findings is most likely to predict problems accurately. A preoperative airway assessment will reveal many of the patients who ultimately will have a difficult airway and it is recommended on that basis. The most common problem will not be missed diagnosis but, rather, pre- dicting many to be difficult when, in fact, they are not. The low specificity of the tests, when combined with the low incidence of difficult airway, leads to the poor posi- tive predictive value. However, a false positive assessment is a benign consequence of the airway evaluation and should not deter clinicians from performing the assessment, leading to the surprise occurrence of difficulties and possibly resulting in either morbidity or mortality. Because a preoperative assessment will predict many difficult airways, it is recommended. However, despite careful preoperative evaluation, difficulties will not be predicted in some instances and strategies to manage the unanticipated difficult airway should be pre-formulated and practised.
- Óptima posición Maccoy no mejora cormack 4 Combitubo: ouble lumen tube with distal and proximal cuffs, presently available in sizes 37 Fr (women and young adults) and 41 Fr (adult males).
- The Canadian Airway Focus Group (CAFG) published their recommendations for management of the unanticipated difficult airway in 1998. 8 They also emphasized the mportance of preoperative evaluation of the airway, although the positive predictive value of this evaluation is low. 36 The key question asked in the CAFG algorithm is whether ventilation is possible or not (Figure 3) . The simple algorithm is based on the strategy that supports the immediate diagnosis of failed ventilation. The choice of the response is determined both by the underlying diagnosis (difficult or failed mask ventilation; difficult laryngoscopy; difficult or failed intubation) and the physician’s chosen alternative. They emphasize that the success of any technique depends on good technique and regular practice, regardless of the device employed. It relies more on skills than on the tools themselves. Unlike the A SA and DAS guidelines, they present special considerations on the obstetric and the paediatric airway. A section is dedicated to extubation of the difficult airway with special emphasis on tracheal tube exchange Obstetrici a: he surgeon should be asked to minimize fundal pressure at time of deliv- ery to red uce the potential for increased gastric pres- sures, regurgitation and aspiration. This may be achieved with either a vacuum or forceps extraction of the fetus.
- Para que cumplan su objetivo se requiere: Vad despierto: tono musc, va permeable General: Niño Pacientes siquiátricos Rechazo técnica Trauma Los algoritmos son una estrategia para disminuir la morbilidad y mortalidad asociada al manejo de los problemas relacionados con la vía aérea. Por tratar de incorporar todas las posibles situaciones tienen un impacto visual negativo. guidelines which include management of the anticipated difficult airway recommend an awake technique. Flexible fibre-optic intubation is the safest, most versatile and most reliable option for this scenario. In the case of unanticipated difficult intubation (mask ventilation possible) national societies recommend different numbers of intubation attempts (including different blades) and the use of alternative supraglottic