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Ventilator settings & clinical application jaskaran singh

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common ventilator settings & their clinical application.

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Ventilator settings & clinical application jaskaran singh

  1. 1. VENTILATOR SETTINGS &THEIR CLINICAL APPLICATIONGuided By-Dr. R L Suman(Assoc. prof.)Presented by-Jaskaran singh(Resident doctor)Chairperson & Head-Dr.Suresh Goyal
  2. 2. Objectives1. Pulmonary physiology2. Assisted ventilation3. Operating mode of ventilation4. Case scenarios in neonate5. Case scenarios in children
  3. 3. Pulmonary Physiology
  4. 4. The Airways• From trachea, the air passes through 10- 23 generations.• First 16 generations = CONDUCTING ZONE, Contain no alveoli, Nogas exchange  Anatomic dead space.• 17th - 19th generation = TRANSITIONAL ZONE, Alveoli start toappear, in the respiratory bronchioles.• 20th - 22nd generations = RESPIRATORY ZONE, Lined with alveoli,alveolar ducts and alveolar sacs, which terminate the tracheobronchialtree
  5. 5. • Gas Exchange– Oxygenation & Ventilation (CO2 removal)• Acid-Base Balance -- Participate in acid-base balance by removingCO2 from the body• Phonation• Pulmonary Defense Mechanisms• Pulmonary Metabolism and the Handling of Bioactive MaterialsLung Functions
  6. 6. • Change in volume (Lung expansion) produced by per unit change in pressure(Work of Breathing)• Denotes the Ease of Distensibility of the lung and chest wall• Compliance is inverse of elasticity or elastic recoil• Low CL= Difficult lung expansion (Stiff Lung) High WOB1. Usually related to condition that reduces FRC2. Have a restrictive lung defect,low lung volume,low minute ventilation3. May be compensated by increased rate.Eg.HMD• High CL= Incomplete exhalation (lack of elastic recoil of lung) & CO2 elimination.1. Conditions that increases FRC.2. Steep slope on P-V curve.3. Have an obstructive lung defect,airflow obstruction,incomplete exhalation,poor gasexchange.• E.g. EmphysemaLung Compliance (CL = ΔV ÷ ΔP)
  7. 7. Lung Compliance Changes and the P-V LoopVolume (mL)Volume (mL)Preset PIPVTlevelsPPawaw (cm H(cm H22O)O)COMPLIANCEIncreasedNormalDecreasedCOMPLIANCEIncreasedNormalDecreasedPressureTargetedVentilation
  8. 8. OverdistensionVolume(ml)Pressure (cm HPressure (cm H22O)O)With little or no change in VTWith little or no change in VTPaw risesPaw risesNormalAbnormal
  9. 9. • Change in pressure per unit change in flow of gases.• Due to friction b/w gas and air conducting system (Airways & ET tube)• Airway resistance = inversely proportional to its radius raised to the 4th power.• If airway lumen decreased half  the resistance/work of breathing 16 times• Newborns and young infants have inherently smaller airways, are especially proneto increase in airway resistance from inflamed tissues and secretions.• High Resistance in dis. with airway obstruction like MAS and BPD• During IMV: Airway resistance varies directly with length of ET & inversely withinternal diameter of ET• Cut ET short*, Use largest appropriate ET size, Suction regularlyAirway Resistance = (PIP-PEEP) ÷ Flow
  10. 10. • Resistance = Pressure change/ Flow• ∆P(PIP - PEEP)  can be treated as WOB• In clinical settings, airway obstruction is one of most frequentcauses of increased WOB Decreased Airflow Decreased MinuteVentilation Hypoventilation CO2 retention• Prolonged high resistance High WOB Respiratory musclefatigue Ventilatory Failure & Oxygenation FailureAirway Resistance & Work of Breathing
  11. 11. • Time const.= Compliance × Resistance = TV / Flow• A pressure gradient between atmosphere and alveoli must be established to moveair into or out of the alveoli.• Tc is the time taken for the transthoracic pressure change to be transmitted as thevolume change in the lungs, i.e. the time it takes for airway pressure and volumechanges to equilibrate b/w the proximal airway and the alveoli.• For practical purposes, all pressure and volume delivery (inflation/ deflation) iscomplete (99%) after 5 Tc.• Inspiratory Tc << Expiratory Tc• Patients with Decreased Compliance (Shorter Tc) ventilate with Smaller TV andFaster Rates to minimize PIP• In pts with increased resistance (Long Tc), a fast rate results in short Ti & Te Inadequate Ti results in lower TV, whereas insufficient Te results in inadvertentPEEP/ auto-PEEP/ intrinsic PEEP  best ventilated with Slower rates and LargerTV.Time constant Tc = Cl × R = ∆V/∆P × ∆P/V
  12. 12. Time constant
  13. 13. Condition Compliance(L/cm H2O)Resistance(cmH2O/L/sec)Time const.(sec)Healthyneonate0.005 20 0.1HMD 0.001 20 Normal 0.02MAS 0.003 100 0.3Implication of CL, R, Tc• During Mechanical Ventilation, inspiratory phase is active and high flow of airLow Tc  So short Ti is sufficient in most situations• Ventilator expiratory phase is passive, so Tc values are essentially applicable toexpiratory time.
  14. 14. • Diseases of the lung parenchyma e.g. ARDS, HMD, Atelectasis, Pneumonia,Pulmonary edema, Pulmonary hemorrhage  FRC is reduced as terminal airwaysbecome fluid-filled or collapsed• The Approach to decreased FRC is to increase MAP to recruit atelectatic areas;(usually achieved by a higher PEEP).• Decreased compliance requires a higher pressure gradient to achieve a given TV.• Volume-Controlled MV  PIP will be higher to achieve a given TV.• Pressure-Controlled MV  Given PIP may result in a lower TV.• May respond to higher ventilator Rates (lungs empty and fill more quickly).• If neither PIP nor Rate is increased sufficiently HypercarbiaDISEASES OF DECREASED COMPLIANCE(Restrictive Diseases)
  15. 15. • Diseases that decrease the caliber of the airway lumen by edema, spasm, orobstruction. Eg.Asthma, Bronchiolitis, Cystic fibrosis etc.• Increased resistance  Impedes gas flow, Gas Trapping  Intrapulmonary shuntand Dead space  Hypoxia & Hypercarbia• Increased resistance requires higher pressure for the gas flow to reach alveoli.• Volume-Controlled MV Higher PIP is required to deliver given TV.• Pressure-controlled MV  TV is lower at the same PIP.• Increased resistance  Increases in Tc  Necessitates Long Ti & Te• If the ventilator Rate is too high and Ti & Te are too short  Gas trapping  Lunghyperinflation, pneumothorax, barotrauma, and reduction in compliance.DISEASES OF INCREASED RESISTANCE(Obstructive Disease)
  16. 16. A. Oxygenation Failure: Hypoxemic respiratory failureA.Severe hypoxemia (PaO2<40) that does not respond to supplemental O2,SpO2 < 90% despite FiO2 > 0.6B.Pneumonia, Pulmonary edema, Pulmonary hemorrhage, and RDS, HMD.• Ventilation Failure: Hypercarbic respiratory failure• Decreased minute ventilation or increased physiologic dead space alveolarventilation is inadequate  Inability to maintain proper removal of CO2Hyper capnia, Respiratory Acidosis• Neuromuscular diseases• Diseases that cause respiratory muscle fatigue due to increased workload(Asthma, COPD and Restrictive lung disease)Respiratory failure can be of Mixed(both oxygenation & ventilation failure)Respiratory Failure
  17. 17. Lung Volumes & Capacities
  18. 18. Alteration in Ventilatory Functions
  19. 19. • FRC= Volume of gas in the lungs after a normal tidal expiration• No muscles of respiration are contracting at the FRC• Here, Tendency of lung to contract = Tendency of the chest wall toexpand (Balance point between the inward elastic recoil of the lungsand the outward elastic recoil of the chest wall)• During inhalation above FRC Inspiratory muscles active• During active exhalation below FRC Expiratory muscles activeConcept of FRC: Basis of PEEP Therapy
  20. 20. • Normally alveolar end expiratory pressure equilibrates with atmosphericpressure(i.e. zero pressure) and average pleural pressure is -5 cmH2O• So alveolar distending pressure is 5 cmH2O (Alveolar-Pleural)• This distending pressure is sufficient to maintain a normal end expiratoryalveolar volume to overcome the elastic recoil of alveolar wall.• If decreased compliance Inward elastic recoil of alveoli is increasedalveolar collapse  Intrapulmonary shunting.• PEEP increases the alveolar end expiratory pressure Increases alveolardistending pressure Re-expansion/ Recruitment of collapsed alveoli Improves ventilation• Thus, PEEP leads to increased V/Q ratio, improves oxygenation, decreasedwork of breathingConcept of FRC: Basis of PEEP Therapy
  21. 21. Physiologic Dead Space= Anatomic + Alveolar1.Anatomic dead space:• Volume of conducting airways, approx. 30% of TV• 1 ml/lb ideal body wt• Decrease in TV leads to relatively higher percentage of TV lost in anatomicdead space• E.g. Neuromuscular dis., Drug Overdose1.Alveolar dead space:• When ventilated alveoli are not adequately perfused• E.g. Decreased cardiac output, Pulmonary vasoconstriction etc.•In health, Physiologic DS= Anatomic DSDead space ventilation
  22. 22. Assisted Ventilation
  23. 23. • Normal respiratory cycle of a spontaneous breath:• Subatmosheric (Negative) intrapleural pressure• Forces by inspiratory muscles  intrapleural pressure more negative(-6 to-8cm H2O )  Sucking of air into lungs• During Expiration, respiratory muscles relax, elastic recoil of chestexhalation• This is called Negative Pressure ventilation• Negative pressure ventilators Iron lung machinesNegative Pressure ventilation
  24. 24. Iron Lung Machine
  25. 25. • PPV causes pressure changes opposite to that ofspontaneous breathing.• During inspiration, Ventilator generates positive pressurein the airways to drive air into lungs• The positive pressure to set on ventilator is based ondisease status (severe HMD- more stiff lung, drivingpressure needed for circuit etc.)Positive Pressure ventilation
  26. 26. Ventilator Breath Cycle
  27. 27. Ventilator Settings & their Significance
  28. 28. • Increased FiO2 Increases PaO2 & thus oxygenation• Very high FiO2 directly toxic to Retina, Lungs, Brain, Gut (free radical injury)a) For pts with severe hypoxemia/ abnormal cardiopulmonary status: initial FiO2 is80-100%, can be decreased to 50%• Both FiO2 & MAP determine oxygenation• Parameter more likely to be effective and less damaging should be used toincrease PaO2• E.g.– if FiO2 is > 0.6-0.7, increase MAPif FiO2 is < 0.3-0.4, decrease MAPb) For pts with mild hypoxemia/Normal Cardiopulmonary status: Initial FiO2 maybe set 40-50%, change as per ABGFiO2
  29. 29. • No positive pressure is safe• PIP in part determines TV & Minute Ventilation• Initial PIP: based on Chest movement & Breath sounds• Normal neonatal lungs 12-14 cm H2O• Mild to moderate lung disease 16-20• Severe lung disease 20-25• Increase in PIP Increases TV, Increases CO2 elimination, Decreases PaCO2,Increases PaO2• Inappropriately high PIP Increased risk of Air leaks & Chronic lung dis.(BPD)• Inappropriately low PIP Lung collapse & insufficient ventilation IncreasedPaCO2, Decreased PaO2, AtelectasisPIP
  30. 30. • PEEP in part determines Lung volume during expiratory phase,improves ventilation perfusion mismatch & prevents alveolar collapse• A minimum physiological PEEP of 3 cmH2O should be used in mostnewborns/Infants• In HMD Initial PEEP= 4-5 cmH2O (increase upto 8)• Increased PEEP improves MAP & oxygenation but also reduces TV& CO2 elimination Increases PaCO2• Inappropriately High PEEP over distended lungs, airleaks,decreased compliance, decreased cardiac outputPEEP
  31. 31. Rate
  32. 32. • Ti : Te Ratio should be kept as physiological as possible = Close to 1:2• Insufficient Ti Inadequate TV delivery, CO2 retention• Insufficient Te Air trapping• Inverse Ti : Te (3:1 or 2:1) used only when conventional strategy fails• Prolonged Expiratory (1:2 or 1:3) in MAS, Asthma• Ti : Te ratio can be changed by manipulating one or more: Flow rate/ Ti/Ti percentage/ Respi. Rate/ Minute Volume (TV x RR)Ti & Te
  33. 33. • A minimum gas flow as required by the machine should be used (5-7 Lt/min.)• Generally this parameter is not altered during the ventilation• Very high gas flow increases Resistance, causes turbulence, airtrapping & air leaks• Low Flow Rate (0.5-3 l/min): produces sine waveform, But maycause hypercapnia, may not be enough to produce required PIP athigh rates (Short Ti)• High Flow Rate (4-10 l/min): produces more square waveform,necessary to attain high PIP at high rates, But may causeBarotrauma & AirleaksGas Flow Rate
  34. 34. Sine wave:• Smoother increase of pressure• More physiologic• But lower MAP is achieved for equivalent PIPSquare wave:• Constant peak flow during entire inspiratory phase• Higher MAP is achieved for equivalent PIP• Longer time at peak pressure• May open up atelectasis and improve distribution of ventilation• High pressure if applied to normal alveoli may result in barotrauma• Can impede venous return if reverse Ti:Te ratio is usedWave Form
  35. 35. • TV in health= 8-10 ml/kg body wt• During Ventilation, Initial TV = 10-12 ml/kg• Lower TV (5-7 ml/kg) can be used (permissive hypercapnia) inARDS/ HMD to minimize the airway pressures and risk ofbarotrauma.• But Lower TV may lead to Acute hypercapnia, increased work ofbreathing, severe acidosis & collapse.Tidal Volume
  36. 36. Goals of Assisted Ventilation• OXYGENATION(PAO2 )• Depends on FiO2 & MAP(Area under curve P-T graph)• MAP=K(PIP×Ti)+(PEEP×Te)(Ti+Te)Oxygenation(Pao2) α Fio2PIPTiK(Gas Flow,Wave form)
  37. 37. Advantage Disadvantage↑ Fio2 Minimizes barotraumaEasily administeredFails to affect V/Q matchingDirect toxicity, especially >0.6↑ PI Critical opening pressure,Improves V/Q matchingBarotrauma: Air leak, BPD↑ PEEP Maintains FRC, prevents collapseSplints obstructed airwaysRegularizes respirationShifts to stiffer compliance CurveObstructs venous returnIncreases expiratory work and CO2Increases dead space↑ TI Increases MAP without increases PICritical opening timeNecessitates slower rates,Lower minute ventilation for given PI —PEEP combination↑ Flow Square wave — maximizes MAP Greater shear force, more barotraumaGreater resistance at greater flowsManipulations to Increase Oxygenation
  38. 38. 2) CO2 Elimination (PaCO2 & pH)α MV α RRα TV α Driving pressure (PIP-PEEP)α Compliance of lungGoals of Assisted Ventilation
  39. 39. Advantage Disadvantage↑ Rate Easy to titrateMinimizes barotraumaMaintains same dead space/TVMay lead to inadvertent PEEP↑ PIBetter bulk flow (improved dead space/TV)More barotraumaShifts to stiffer compliance curve↓ PEEP Widens compression PressureDecreases dead spaceDecreases expiratory loadShifts to steeper compliance curveDecreases MAPDecreases oxygenation (alveolarcollapse)Stops splinting obstructed /closedairways↑ Flow Permits shorter TI, longer TE More barotrauma↑ TEAllows longer time for passive expirationin face of prolonged time ConstantShortens TIDecreases MAPDecreases oxygenationManipulations to Increase Ventilation
  40. 40. Adequacy Of Alveolar Ventilation• Oxygenation Index OI= MAP×Fio2×100PaO2>15 means severe repiratory distress>40 min in patient on conventionl ventilation, 2 samples30 min apart indication for ECMO.• Ventilation Index VI=RR×PIP×PCO21000>90 for 4hr means poor prognosis.
  41. 41. Classificationof Mechanical Ventilators
  42. 42. The mechanical ventilator can control 4 primary variables duringinspiration—Pressure, Volume, Flow and Time1.Pressure controlled ventilator ventilator controls transrespiratory system pressure i.e. airway pressure-body surfacepressure.•Means that pressure level that is delivered to the pt will not vary inspite of changes in compliance or resistance.•Further classified as PPV & NPV•Trans respiratory pressure gradient is generated in both Causeslung expansionControl Variables
  43. 43. 2. Volume controlled ventilator:• Volume delivery remains constant with changes in compliance& resistance, while the pressure varies.• Volume measurement and feedback signal is must3. Flow controlled ventilator:• Allows the pressure to vary with changes in compliance &resistance while directly measuring and controlling flow4. Time controlled ventilator:• Measure and control inspiratory & expiratory time• Allows pressure and volume to vary with changes in compliance &resistance
  44. 44. PRESSURE VENTILATION VOLUME VENTILATIONParameters set bythe operator• PIP, PEEP, Rate, FIO2, Ti • TV, PEEP, Rate, FIO2, TiParametersdetermined by theventilator• TV, Te • PIP, TeAdvantages • Higher MAP with the same PIP• Lung protective for noncompliant lungs• Guaranteed minute ventilationDisadvantages • Does not accommodate for rapid changesin pulmonary compliance• Not optimal for patients with anendotracheal tube with large leaks• Minute ventilation not guaranteed • PIP May reach dangerous level ifcompliance is worseningPRESSURE V/S VOLUME VENTILATION
  45. 45. • It combines two control variables (pressure & volume),that are regulated by independent feedback loops so thatdelivered breath switches b/w pressure control andvolume control.• Patient receives mandatory breaths that are VolumeTargeted, Pressure Limited, and Time cycled.• PRVC (pressure regulated volume control),• VAPS(volume assured pressure support),• VG(volume guarantied) is also work on dual mode.Dual-Control Mode
  46. 46. • A ventilator supported breath is divided into 4 distinct phases: 1)Change from expiration to inspiration 2) Inspiration 3) Changefrom inspiration to expiration 4) Expiration.• When 1 of the 4 variables (Pressure, Volume Flow & Time) isexamined during a particular phase, it is termed as “Phasevariable”• Trigger Variable• Limit Variable• Cycle VariablePhase variables
  47. 47. • What determines the start of inspiration?1. Time triggered: Breath is initiated and delivered when a preset timeinterval has elapsed.• The rate control on ventilator is a time triggering mechanism. At given timetrigger interval, the ventilator automatically delivers one mechanicalbreath without regard to patient’s effort or requirement1. Pressure triggered: Beginning of spontaneous inspiratory effort by ptDrop in airway pressure Sensed by ventilator as a signal to initiateand deliver a breath.• The amount of negative pressure, a pt must generate to trigger theventilator is Sensitivity Level (-1 to -5 cm H2O)1. Flow triggered: More sensitive & responsive to pt’s effort1. Continuous flow is given(delivered=returned)pt effort part of flowgoes to pt returned flow< delivered flow sensed by ventilator toinitiate breathTrigger Variable
  48. 48. • What is set to its upper limit during inspiration?• If one variable (volume/pressure/flow) is not allowed to rise above apreset value during the inspiratory time, is termed as Limit Variable• Inspiration does not end when this variable reaches its preset value,breath delivery continues, but the variable is held at the fixed presetvalue(max.)• Pressure limited/ Volume limited/ Flow limitedLimit Variable
  49. 49. • What ends inspiration?• This variable is measured and used as feedback signal byventilator to end inspiratory flow delivery, which thenallows exhalation to begin• Most newer ventilators are Flow controlled, Time cycledCycle Variable
  50. 50. Operating Modes Of Ventilator
  51. 51. 1) Spontaneous2) Positive End Expiratory Pressure (PEEP)3) Continuous Positive Airway Pressure (CPAP)4) Bi-level Positive Airway Pressure (Bi-PAP)5) Controlled Mandatory Ventilation (CMV)6) Assist Control (AC)7) Intermittent Mandatory Ventilation (IMV)8) Synchronized Intermittent Mandatory Ventilation (SIMV)9) Mandatory Minute Ventilation (MMV)10) Pressure Support Ventilation (PSV)1) Spontaneous2) Positive End Expiratory Pressure (PEEP)3) Continuous Positive Airway Pressure (CPAP)4) Bi-level Positive Airway Pressure (Bi-PAP)5) Controlled Mandatory Ventilation (CMV)6) Assist Control (AC)7) Intermittent Mandatory Ventilation (IMV)8) Synchronized Intermittent Mandatory Ventilation (SIMV)9) Mandatory Minute Ventilation (MMV)10) Pressure Support Ventilation (PSV)Operating Modes
  52. 52. Operating Modes11) Adaptive Support Ventilation (ASV)12) Proportional Assist Ventilation (PAV)13) Volume Assured Pressure Support (VAPS)14) Pressure Regulated Volume Control (PRVC)15) Volume Ventilation Plus (VV+)16) Pressure Control Ventilation (PCV)17) Airway Pressure Release Ventilation (APRV)18) Inverse Ratio Ventilation (IRV)19) Automatic Tube Compensation (ATC)11) Adaptive Support Ventilation (ASV)12) Proportional Assist Ventilation (PAV)13) Volume Assured Pressure Support (VAPS)14) Pressure Regulated Volume Control (PRVC)15) Volume Ventilation Plus (VV+)16) Pressure Control Ventilation (PCV)17) Airway Pressure Release Ventilation (APRV)18) Inverse Ratio Ventilation (IRV)19) Automatic Tube Compensation (ATC)
  53. 53. Modes of Ventilation• Basically there are three breath delivery techniques used withinvasive positive pressure ventilation• CMV – controlled mode ventilation• SIMV – synchronized• Spontaneous modes
  54. 54. • Three basic means of providing support for continuousspontaneous breathing during mechanical ventilation• Spontaneous breathing• CPAP• Bi-PAP• PSV – Pressure Support VentilationSpontaneous Modes
  55. 55. • Patients can breathe spontaneously through a ventilator circuit;sometimes called T-Piece Method because it mimics having thepatient ET tube connected to a Briggs adapter (T-piece)• Role of ventilator in this mode is to provide:1. Inspiratory flow in a timely manner2. Adequate flow to meet pt’s inspiratory demand (TV & inspiratoryflow)3. Provide adjunctive mode as PEEP to complement pt’s spontaneousbreath• Disadvantage-May increase patient’s WOB with older ventilatorsSpontaneous Modes
  56. 56. • PEEP increases end-expiratory/ baseline airway pressure to morethan atmospheric pressure.• Not a “Stand-alone” Mode, rather it is applied in conjugation withother modes.• E.g. with CPAP, AC, SIMV• Indications for PEEP:1. Decreased FRC & Lung compliance2. Refractory Hypoxemia, Intrapulmonary ShuntingPEEP (Positive End Expiratory Pressure)
  57. 57. Modes of Ventilation-CPAP• Ventilators can provide CPAP for spontaneouslybreathing patientso Positive intrapulmonary pressure (PEEP) is appliedartificially to the airways of a spontaneously breathing baby,throughout the respiratory cycle, so that distendingpressure is created in the alveolio Distinct from IPPV or IMV in which breathing is taken overby ventilator completely and increase in pressure occursduring both inspiratory as well as expiratory phasesseparatelyo CPAP ≈ Half Filled Air Balloono Advantages-Ventilator can monitor the patient’s breathingand activate an alarm if something undesirable occurs
  58. 58. • Independent positive airway pressures to both inspiration and expiration (IPAP& EPAP)• IPAP provides positive pressure breaths and improves ventilation & hypoxemiad/t hypoventilation.• EPAP is in essence CPAP which increases FRC, improves alveolar recruitmentImproves PaO2• Used in cases of Advanced COPD, Chronic ventilatory failure, Neuromusculardis., Restrictive chest wall dis.• Bi-PAP device can be used as CPAP• Initiate with IPAP=8, EPAP=4, then gradual increments of 2cmH2O in bothBi-PAP: Bi-level Positive Airway Pressure
  59. 59. • PSV applies a preset pressure plateau to the airways for the duration ofa spontaneous breath.• A Pressure supported breath is: Patient Triggered: All ventilator breaths are triggered by patient Pressure Limited: Maximum pressure level can not exceed preset pressuresupport level, TV varies with inspiratory flow demand. Flow Cycled: When pt’s inspiratory flow demand decreases to a preset minimalvalue, inspiration stops and expiration starts.• PSV can be used with spontaneous breathing in any ventilator mode(usually SIMV) as a PRESSURE BOOST• Patient has control over Rate & Ti both.• Adv.: Increases spontaneous TV, Decreases spontaneous RR, DecreasesWork of breathing.Pressure Support Ventilation-
  60. 60. Pressure Support Ventilation (PSV)
  61. 61. PSV during SIMV• Spontaneous breaths during SIMV can be supported with PSV (reducesthe WOB)PCV – SIMV with PSV10 cm H2O35 cm H2O
  62. 62. • Ventilator delivers preset TV/Pressure at a Time triggered rate• Ventilator controls both the pt’s TV & RR, So ventilator controls the pt’s Minute Volume• Pt can not change RR or breath spontaneously, so only used when pt is on sedation/respiratory depressants/ NM blockers.• Indications of CMV:1. Severely distressed pt, vigorously struggling Rapid inspiratory efforts Asynchrony/Fighting in the initial stages CMV2. Tetanus/ status epilepticus Interrupts ventilation delivery3. Crushed chest injuries d/t Paradoxical chest movementsControlled Mandatory Ventilation (CMV)
  63. 63. • Every breath delivers a preset mechanical TV (Volume Cycled) either assisted or controlled• If Pressure/Flow triggered by Pt’s spontaneous effort = ASSIST• If Time triggered by ventilator = CONTROL (Safety Net)• Adv.: 1) Work of breathing is handled by ventilator,• 2) Pt himself can control RR & therefore minute ventilation to normalize PaCO2• Disadv.:Pt with inappropriately high respiratory drive* High assist rate despite low PaCO2 Hypocapnia & Respiratory alkalosis• Indi.= Mostly used for a pt. with stable respiratory drive to provide full ventilatory support whenpt. first placed on ventilator.Assist Control (ACMV)
  64. 64. • Ventilator delivers control/mandatory breaths at a set time interval independent of pt’sspontaneous respiratory rate.• Allows the pt. to breath spontaneously at any TV in b/w control breaths• Was the first widely used mode that allowed partial ventilatory support.• Disadv.: Ventilator Asynchrony, Breath Staking.• Not used nowadays• Gave birth to SIMVIntermittent Mandatory Ventilation (IMV)
  65. 65. • Mandatory breaths are synchronized with pt’s spontaneous breathing efforts to avoid asynchrony.• Ventilator delivers a mandatory breath at or near the time of a spontaneous breath.• The time interval (just prior to time triggered ventilator breath) in which ventilator is responsive topt’s spontaneous breath is= “Synchronization Window”, usual window is 0.5 sec*• SIMV permits the pt. to breath spontaneously to any tidal volume the pt’ desires.• The gas source for spont. breathing is supplied by “demand valve” always pt. triggered• Spontaneous breaths taken by the pt. are TRULY SPONTANEOUS Rate & TV are dependent on pt,humidified gas at selected FiO2 is given by ventilator.Synchronized IMV (SIMV)
  66. 66. • SIMV allows patients with an intact respiratory drive to exercise inspiratory muscles betweenassisted breaths, making it useful for both supporting and weaning intubated patients• Indication: To provide partial ventilatory support.• When a pt placed on ventilator Full ventilatory support is appropriate for initial 24 hrs  ThenTrial of partial ventilatory support on SIMV (pt is actively involved in providing part of minutevolume) Gradually decrease the mandatory rate as tolerated by the pt.• Adv:1. Maintains respiratory muscle strength/ avoids muscle atrophy2. Reduces V/Q mismatch3. Decreases MAP4. FACILITATES WEANING ( Using small decrements* in mandatory rate)Synchronized IMV (SIMV)
  67. 67. • neonatal ventilation has been accomplished using traditional time-cycledpressure-limited ventilation (TCPL).• In this mode of ventilation, a peak inspiratory pressure is set by the operator,and during inspiration gas flow is delivere to achieve that set pressure, hencethe term pressure-limited (PL) ventilation.• The volume of gas delivered to the patient in this mode however variesdepending on pulmonary mechanics such as compliance or stiffness of thelungs.• At low compliance (‘stiff lungs’) such as occurs early in the course ofrespiratory distress syndrome (RDS), a given pressure generates lower tidalvolume as compared to later in the course of the disease when the lungs aremore compliant (‘less stiff’) when the same set pressure will lead to deliveryof larger tidal volumes.• This is important clinically as with improvement in compliance such as afterexogenous surfactant therapy, the ventilator pressure has to be weaned bythe operator to prevent alveolar over distension resulting from excessive tidalvolume delivery.TCPL( Time cycled pressure limit) ventilation
  68. 68. • An additional safety function of SIMV mode, that provides apredetermined minute ventilation when pt’s spontaneousbreathing effort becomes inadequate.• E.g. Apnea mandatory rate increased automatically tocompensate for decrease in minute ventilation caused by apnea.• Prevents hypercapnea by automatically ensuring a minimum presetminute ventilation.Mandatory Minute Ventilation (MMV)
  69. 69. • PRVC provides volume support with the lowest possible PIP bychanging the Peak Flow & Ti• PRVC is a Dual control mode: Both TV & PIP can be controlled at sametime• Airflow resistance = (PIP-PEEP) ÷ Flow• At a constant flow & PEEP, increased airflow resistance requires higherPIP. PRVC lowers the flow to reduce PIP.• At a constant PIP, increased airflow resistance lowers flow. PRVCprolongs Ti to deliver the target TV.• Works with CMV or SIMV (in viasys ventilator) mode• Volume cycled, Time / Pt triggeredPressure Regulated Volume Control (PRVC)
  70. 70. • VV+ is an option that combines two different dual mode volumetargeted breath types: VC+ and VSa) VOLUME CONTROL PLUS (VC+):• VC+ is used to deliver mandatory breaths during AC and SIMV modes• Intended to provide a higher level of synchrony than standard volumecontrol ventilation.• Target TV & Ti is set  Ventilator delivers a single test breath usingstandard volume & flow to determine compliance Then Targetpressures for subsequent breaths are adjusted accordingly tocompensate for any TV differencesVolume Ventilation Plus (VV+)
  71. 71. b) VOLUME SUPPORT (VS):• Target TV is set and ventilator uses variable pressure support levels toprovide the target TV.• Only target TV is set (not the Ti or Mandatory Rate)  ventilator deliversa single spontaneous pressure support breath  and then uses variablepressure support levels to provide target TV.• Mandatory Rate and minute ventilation is determined by triggeringeffort of the patient.• Used during “Awakening from anesthesia”Volume Ventilation Plus (VV+)
  72. 72. • Like half Filled air balloon• Pt. is allowed to breath spontaneously at an elevated baseline (i.e. CPAP). This elevated baselineis released periodically to facilitate expiration.• Newer mode, indicated in patients with lower compliance e.g. ARDS in which conventionalvolume controlled ventilation requires very high PIP• APRV can provide effective partial ventilatory support with a lower PIP in these pts.Airway Pressure Release Ventilation (APRV)
  73. 73. • Delivers small Tidal volumes at very high rates, reduces the risk ofbarotrauma.• Limited to the situations in which conventional ventilation has failed• Categorized by rate and the method used to deliver the TVHigh Frequency Ventilation (HFV)Type of HFV Rate per min.HFPPV (HF Positive Pressure Ventilation) 60 - 150HFJV (HF Jet Ventilation) 240 - 660HFOV (HF Oscillatory Ventilation) 480 - 1800
  74. 74. Use pressure control rather than volume controlSIMV mode can be used for any conditionApneic – SIMV mode with normal respiratory rateSpontaneous breathing (not adequate) -Set a minimum RR of 10- 20 /minTachypneic child fighting with ventilator -Set higher rate & adequately sedate the childIn addition to SIMV, every spontaneous breath can be pressuresupported provided RR is not too highWhich mode for which condition ?
  75. 75. Case scenarios in Neonate
  76. 76. Retraction moderate or severeRR > 70/minCyanosis even after oxygenationIntractable apneic spellImpending or existing shockPaO2 < 50, PCaO2 > 60, PH < 7.25Indication for mechanical ventilation-Neonate
  77. 77. Setting Infant withNORMAL LUNGFiO2 0.5 or to target SPO2 85 – 95 %Respiratory rate 30-40 / minute to maintain normal PaCO2(higher rate is requried if cerebral odema & Raised ICT)PIP 10 - 12 cm H2O , just enough to produce minimal chestrise ( VT 3-5ml/kg )PEEP 4 - 5 cm H2O ( to achieve normal FRC : 7-9 post rib)Ti 0.3-0.4 secFlow rate 4-6 l/minSuggested initial ventilator setting inBirth asphyxia & apnea (Normal lung)Target blood gas Ph 7.3 to 7.4, PaCO2 35 to 45 , PaO2 60 - 90
  78. 78. Setting Infant with RDSFiO2 0.5 or to target SPO2 85 – 95 %Respiratory rate 40-60 / minute(higher)PIP 12-20 cm H2O(dependa upon severity) , just enoughto produce minimal chest rise ( VT 3-5ml/kg )PEEP 4 - 7 cm H2O ( to achieve normal FRC : 7-9 post rib)Ti 0.2 - 0.3 secFlow rate 6-8 l/minSuggested initial ventilator setting inHyaline membrane disease / RDSTarget blood gas Ph 7.25 to 7.35, PaCO2 45 to 55 , PaO2 50 - 70
  79. 79. Setting Infant with MASFiO2 FiO2 to target SPO2 90 – 95 %Respiratory rate 40-60 / minutePIP 12-16 cm of H2O, just enough to produce minimalchest rise ( VT 3-5ml/kg )PEEP Low to moderate PEEP (0 - 3 cm H2O)Ti 0.4- 0.5 sec (Te 0.5 -0.7 sec, I:E = 1:3 – 1:4)Flow rate 6-8 l/minSuggested initial ventilator setting inMASTarget blood gas Ph 7.25 to 7.35, PaCO2 45 to 55 , PaO2 50 - 70
  80. 80. Setting Infant with PPHNFiO2 High FiO2 to target SPO2 90 – 95 %Respiratory rate High rate 50-70 / minutePIP Optimal PiP , just enough to produce minimal chestrise ( VT 3-5ml/kg )PEEP 4 - 6 cm H2OTi 0.3- 0.4 secFlow rate 6-8 l/minSuggested initial ventilator setting inPPHNTarget blood gas Ph 7.3 to 7.4, PaCO2 40 to 45 , PaO2 80 - 100
  81. 81. Observe infant for cyanosis , absence of retraction, chest wallmovement.If ventilation is inadequate increase PIP by 1 cm H2O every fewbreath until air entry & chest rise adequate.If oxygenation is inadequate increase FiO2 by 0.05 every minuteUntil cyanosis abolish or SPO2 = 90-95 %.Initial pressure that result in adequate chest expansion & result intidal volume 3-5 ml/kg should be taken as initial PIP setting.PEEP should not exceed 8 cm H2O in most situation.Initiation
  82. 82. CLINICAL PARAMETERPink colourAdequate chest expansionAbsence of retractionAdequate air entryPrompt capillary filling within 2 secondNormal blood pressurePULSE OXYMETERYOxygen saturation 90-95 %BLOOD GASESPaO2 50-80 mm HgPaCO2 40-50 mm Hg (in chronic cases up to 60 mm Hg)PH 7.35-7.45Adequacy of ventilation
  83. 83. Blood gasabnormamalityCorrective measureFiO2 Rate PIP PEEP TiHypercapneaPaCO2 > 50mm HgHypocapneaPaCO2 < 35mm HgHyperoxiaPaO2 > 100mm HgHypoxemiaPaO2 < 50Change in ventilatory parameters
  84. 84. •Change should be made in short steps•PIP &PEEP should be altered only 1 cm H2O at time•Rate by 2 breath/min, FiO2 – 5%•Blood gas estimation should be performed 20-30 min after every change•To minimize adverse effect of one parameter simultaneously step up or stepdown various settingFiO2 - 0.95, PIP-18 cm, PEEP- 4 cm H2OPeep requirement go in consonance with FiO2Changing ventilator settingFiO2 PEEP0.3 30.4 40.5 5>o.8 8
  85. 85. •HMD weaning attempted on 3rdor 4thday especially at timewhen maximum diuresis occurs.•HMD it is important to reduce setting when complianceimproves if not changed barotrauma will result.•Uncomplicated MAS or pneumonia can be weaned muchearliar.•Iv aminophylline is started 24 hours prior to expected time ofextubation .•Dexamethasone 0.15 mk/kg IV for post extubation stridor.•Infant is attached to CPAP mode before extubation.Weaning from ventilator
  86. 86. Reduce PIP to 25 cm H2OAlternately reduce PIP& FiO2Reach PIP 20 cm, FiO2 0.6Pulse oxymetry andPaO2Clinical and PCaO2PaCO2FiO2 and PEEPPIPRate and TiWeaning
  87. 87. Case scenarios in children
  88. 88. Respiratory failureApnea / respiratory arrestImpending Respiratory failureCardiac insufficiency & shockNeurological dysfunctionEverything ends hereAcute ventilatory failurePH < 7.3, PaCo2 > 50 mm HgSevere hypoxemiaPaO2 < 40, SaO2 < 75%Indication of ventilation
  89. 89. In shock use higher FiO2 up to 1.o initiallyIn encephalopathy higher RR to cause hypocarbia (30-35 mm Hg)Setting - Normal lungPiP 15-20 cm H2OVt 6-8 ml/kgPEEP 3-4 cm H2ORate 40/min (infant)20-30 /min (older children)I:E ratio 1:2
  90. 90. Respiratory rate higher than normalHigher PIPHigher PEEPPneumoniaPneumonia Normal lungPiP 20-25 cm H2O 15-20 cm H2OVt 6-8 ml/kg 6-8 ml/kgPEEP 4-5 cm H2O 3-4 cm H2ORate 40-50/min (infant)30-40 /min (olderchildren)40/min (infant)20-30 /min (olderchildren)I:E ratio 1:2 1:2
  91. 91. PEEP is kept low to prevent air trappingLower RR and prolonged Te to ensure air expulsionMaintain oxygenation and accept hypercarbia up to 60 cm H2OAsthma / Bronchiolitisasthma PneumoniaPiP <20-25 cm H2O 20-25 cm H2OVt 6-8 ml/kg 6-8 ml/kgPEEP 3-4 cm H2O 4-5 cm H2ORate 30-40min (infant)20-30 /min (olderchildren)40-50/min (infant)30-40 /min (older children)I:E ratio 1:3 to 1:4 1:2
  92. 92. High degree of collapsibility & very low compliance .Don’t exceed PIP >35 cm H2O.FiO2 preferably kept below < o.6 .Hypercapnea to degree is acceptable.ARDSPiP < 35 cm H2OVt 4-6 ml/kgPEEP 5-10 cm H2ORate 40/min (infant)20-30 /min (older children)I:E ratio < 1:2 to inverse ratio
  93. 93. Measure to reduce barotrauma -•Permissive hypercapneaHigher PaCO2 is acceptable as long as PH > 7.25.•Permissive hypoxemiaPaO2 55to 60 mm Hg SaO2 of 88 – 90 % is acceptable for limiting PEEP & FiO2Inverse ratio ventilation-•Ratio of 2:1 and 4:1•Increase in mPaw during IRV help to reduce alveolar•collapse , shunting, V/Q mismatch•To achieve same ventilation you need lesser PIP & PEEP•Auto PEEP – also reduce shunting & improve oxygenationContinue..
  94. 94. Don’t just increase FIO2 , increase PIP & PEEPSaturation worsening with PEEP, suspect low cardiac outputor air leakDon’t forget other measure to improve oxygenationManage shockNormal hemoglobinDeepen sedationNormothermiaHypoxia
  95. 95. In asthma increase expiration (Te)Decrease PEEPDecrease Co2 production – sedation, cooling bodyEt tube blockade / malpositionedHigh PaCO2
  96. 96. Midzolam drip - 0.2 mg/kg loading dose1-3 mcg/kg/minNeonate - morphineSkeletal muscle relaxantVecuronium – o.o5 mg/kg/hrPancuronium – longer acting (0.07 mg/kg/hr)Analgesia & sedation
  97. 97. PositionEt tube careEt suctionChest physiotherapyMaintaince fluid – restrictedMaintain blood sugar / ElectrolyteMaintain tempratureTropic feed / TPNNaso-oropharyngeal carePrevention of IVH- sound proofingNursing of child on ventilator
  98. 98. FixationSkin SafetyHyperoxygenationGentle atraumatic suctionAsepsisEt tube care & suction
  99. 99. DOPED = Displacement O = ObstructionP = Pneumothorax E = Equipment failureCheck tube placement – is chest rising ? breath sound equal ?When in doubt take ET tube out & start manual ventilationCheck ABG & Chest x ray for pneumothorax & worsoning lungpathologyExamine ventilator & circuitExamine for shock & sepsisIf no other reason for hypoxemia :Increase sedation /muscle relaxationPatient fighting & desaturating
  100. 100. 1. VENTILATOR-ASSOCIATED PNEUMONIA (VAP)2. HYPOTENSION (d/t elevated intrathoracic pressures with decreased VR)3. GI Effects: Stress ulceration, Mild to moderate cholestasis4. VOLUTRAUMA = Damage caused by over distention; sometimes called high-volume or high end-inspiratory volume injury5. ATELECTOTRAUMA = Lung injury associated with repeated recruitment andcollapse, theoretically prevented by using adequate PEEP, sometimes calledlow-volume or low end-expiratory volume injury6. BIOTRAUMA = Pulmonary and systemic inflammation caused by the releaseof mediators from lungs subjected to injurious mechanical ventilation7. OXYGEN TOXIC EFFECTS = Damage caused by a high concentration of inspiredoxygen8. BAROTRAUMA = High-pressure–induced lung damage, clinically manifest byinterstitial emphysema, pneumo mediastinum, subcutaneous emphysema, orpneumothorax.Complications of Mechanical Ventilation
  101. 101. No clinical need for increased support – 24 hrsSpontaneous respirationFiO2 requirement < 0.5Improving breath sound, decreased secretionImproving chest x rayHemodynamically stableLGB – muscle power & cough, Gag reflexEncephalitis – improvement in GCS scaleAirway edema – air leak at below 20 cm H2O PiPWeaning a child begins with improvement inclinical condition
  102. 102. How to wean-•Decrease FiO2 by 5% to keep SPO2 > 94 % (o.6).•Decrease PEEP by 1-2 cm to 4-5 cm H20.•Alternate FiO2 & PEEP after that.•Decrease SiMV rate by 3-4 breath/min to reach SiMV rate 5 .•Decrease PiP & pressure support ( 2 cm each time by titrating with Vt – 5 ml/kg ).•Ventilator rate & PiP can be changed alternatively.•ABG is true guide what you have done.When to stop further weaning-•SPO2 falls < 94% & require to increase FiO2.•Spontaneous respiration is fast & distress.•Agitation or lethargic.•Hypercarbia in blood gases.•e.g. simv rate reduced from 20 to 15/min but patient spontaneous rate increasedfrom 25 to 50/min.Continue..
  103. 103. Extubation procedure•Keep NBM & adequate suctioning•Keep O2 source ready•Nebulization with beta stimulant or adrenaline•Dexamethasone 0.15 mk/kg IV for postextubation stridor•CPAP may be helpful in preventing reintubation•ABG after 20 min of extubation•Post extubation chest x ray - if clinicaldeteriorationWhen to extubate-•SIMV respiratory rate of 5/min.•pressure support of 5-10 cm above PEEP.•PEEP - 5 cm H2O•FiO2 < 0.3 with SPO2 > 94 %•Good breath sound, minimal secretion•Good airway reflexes•Air leak around tube•Awake patient•Adequate muscle tone•Normal electrolyte
  104. 104. Retraction, tachypneaRestlessness, lethargyHypoxiaHypercarbiaAcidosis ( early sign to react)Chest x rayFailure of extubation