1. Perioperative management
of morbidly obese patient for
non bariatric surgery
Dr vivek pushp
Deptt. of anesthesiology & ccm
BRD medical college gorakhpur

2. WHAT IS OBESITY?

3. OBESITY
OBESITY A
metabolic disorder
that is primarily
induced and
sustained by an
over consumption or
under utilization of
caloric substrate.
 Obesity is a
complex
multifactorial
(genetic,enviorment
al,psychological)dise
ase


4. “Across the globe Obesity
become the most common
Nutritional disorder and it is
second only to smoking as a
preventable cause of death.
In anesthetic practice it
present special challenges
for both regional and
general anaesthesia”.

5. INCIDENCE
INCIDENCE Worldwide adult
population 7%
 In Affluent cultures, the poor have
the highest prevalence (27% US and
17% UK population)
 In Developing world, affluent are at
the highest risk.
 Obese school children 60-85%


6. CAUSES



Genetic
predispositio
n
Sex/ Race/
Economic
status
Psychological
Environment
al/
Emotional/
Cultural

8. Lean Body Mass Formula
Lean Body Mass = Body Weight –
(Body Weight x Body Fat %) :
 Lean body mass is comprised of
everything in your body besides body
fat.
 Your lean body mass includes:

◦
◦
◦
◦
◦
organs
blood
bones
muscle
skin

9. Quantifying Obesity
Height/ Weight
 nomograms
 The Broca Index
 Body mass Index


10. The Broca`s Index

Ideal body weight(IBW) (kg)
◦ For Female = Height (cm) – 105
◦ For Male = Height (cm) – 100

11. BMI=Body Weight (kg)/
Height2 (meters)
BMI is defined as the patient's
weight, measured in kilograms, divided
by the square of the patient's height,
measured in meters, which yields a
measurement bearing the unit kg/m2.
 Overweight is defined as a BMI of >25
kg/m2
 Obesity as a BMI >30
 Extreme obesity (old term "morbid
obesity") as a BMI of >40.


12. BMI (kgm-2)
Definition
<18.5
18.5-24.9
25-29.9
30-39.9
40-49.9
Underweight
Ideal Weight
Overweight
Obese
Morbidly Obese
50-59.9
60-69.9
>70
Super Obese
Super Super Obese
Hyper Obese
 Other
method for quantifying obesity includeSkin fold thickness,Densiometry(under water
weighing),DEXA,CT,MRI,Electrical Impedence.

13. EFFECTS OF OBESITY

14. Cardiovascular
Changes






Increased blood volume and cardiac output
leading to cardiomegaly, left ventricular
hypertrophy and a potential for left
ventricular failure.
Hypertension and ischaemic heart disease
Venous access can sometimes be difficult.
Thromboembolism risk is increased.
The risk of pulmonary embolus and DVT is
doubled
Venous return is reduced.

15. Cardiomyopathies
 Cardiac failure
 Arrhythmias
 Sudden cardiac death
 Dyslipidaemias
 Venous insufficiency
 Cerebrovascular disease
 Peripheral vascular disease
 Atherosclerotic changes


16. Respiratory Changes




Reduced compliance (both chest wall and lung),
in the airway resistance and reduced FRC will
pre-dispose to atelectasis, increased shunt and
hypoxia.
70% in work of breathing and a four fold in
the Oxygen cost of breathing occur in case of
morbid obese.
Pulmonary vasoconstriction, pulmonary
hypertension and right ventricular hypertrophy.
These patients must be pre-oxygenated as they
desaturate much quicker than non-obese (3–5
times).decrease in FRC impairs the ability of
obese pts to tolerate periods of apnea ,such as
during direct laryngoscopy for tracheal
intubation.

17. Pulmonary mechanics:


Inspiratory reserve volume(IRV),
expiratory reserve volume(ERV),
functional residual capacity(FRC),
vital capacity(VC),
total lung capacity(TLC) and
minute ventilation(MV)( )
but
tidal volume(TV) and residual volume(RV) (→).
FRC may be below the closing capacity resulting
in the small airway closure→ V/P mismatch→
right to left shunting and hypoxemia

18. 
General anesthesia will accentuate these changes such that a
50% decrease in FRC occurs in obese anaesthetised pts
compared with a 20% decrease in non obese individuals..
Worsened in:
Improved by:
◦ Supine Position
PEEP
◦ Trendelenberg position
Reverse Trendelenberg
Normal
Lung volume

Obese, awake
Closing volume
Functional
residual
capacity
Obese anaesthetized
Residual volume

19. Oxygen consumption and carbon dioxide production
are increased.
 There is a higher incidence of difficult laryngoscopy
and intubation.
 The incidence of difficult intubation in morbid
obesity is around 13% Altered anatomy:

◦
◦
◦
◦
◦
◦
◦
Increase in soft tissue
Reduced head and neck mobility
Large tongue
Short neck
Large breasts
Anterior larynx
Restricted mouth opening

20. Obstructive sleep apnoea- 5%
Airflow cessation of >10 secs. and characterised by
frequent episodes of apnea or hypopnea during sleep.
 RISK FACTORS:

◦ Large collar size (over 16.5 inches)
◦ Evening alcohol consumption
◦ Pharyngeal abnormalities
PATHOPHYSIOLOGY:Passive collapse of the
pharyngeal airway during deeper planes of sleep.
 CLINICAL FEATURES:

◦
◦
◦
◦
Snoring and intermittent airway obstruction
Resultant hypoxaemia and hypercapnia
Arousal and disruption of sleep
Daytime somnolence.

21. Pathophysiology of Sleep Apnea
Awake: Small airway + neuromuscular compensation
Sleep Onset
Hyperventilate: correct
hypoxia & hypercapnia
Loss of neuromuscular
compensation
+
Airway opens
Decreased pharyngeal
muscle activity
Pharyngeal muscle
activity restored
Airway collapses
Arousal from sleep
Apnea
Hypoxia &
Hypercapnia
Increased ventilatory
effort

22. Clinical Consequences
Sleep Apnea
Sleep Fragmentation
Hypoxia/ Hypercapnia
Cardiovascular
Complications
Excessive Daytime
Sleepiness
Morbidity
Mortality

23. Obstructive Sleep Apnea Hypopnea
Syndrome(OSAHS)

5 or more apneic(complete cessation of air flow) events or 15 or
more hypopneic(50% reduction of air flow) events per hour of
sleep despite of maintaining adequate ventilatory capacity
associated with a decrease in SpO2 ≥ 4%.

Regular
hypopneic
and
apneic
events →
hypoxemia
and
hypercarbia → rptd stimulation of resp centre → gradual
desensitisation
of
resp
centre→
hypoventilation,Hypercapnia ( OHS)

Pickwickian Syndrome is OHS with cor pulmonale.
Alveolar

25. Obesity hypoventilation syndrome
(pickwickian syndrome)
Loss of the sensitivity to hypercarbia
resulting in a combination of hypoxia, Cor
Pulmonale and Polycythaemia,respiratory
acidosis,pulmonary hypertension,and right
ventricular failure.
 Diagnosis –Polysomnography (Apnea-Hypopnea
index (AHI)), A score of 5-15 is „mild OSA‟,
15-30 „moderate‟, and „severe OSA‟ is over 30
 Treatment

◦ Removal of precipitants
◦ Surgical(uvulopalato
pharyngoplasty)
◦ Weight loss
◦ Nocturnal CPAP

26. Obesity
OSA or OHS
Increased blood volume
Increased cardiac output
Hypoxia/hypercarbia
LV enlargement
Pulmonary arterial
hypertension
RV enlargement
and
hypertrophy
LV Hypertrophy
Hypertension
RV failure
Pulmonary venous
hypertension
LV failure
Ischaemic
heart
disease
Adams jp murthy PG;obesity in anesthesia and intensive care.br j anaesth
2000;85;91-108

27. 
This presents the
anaesthetist with
a patient who may
be difficult to
bag-mask
ventilate,
difficult to
intubate and will
desaturate
quickly

28. Anatomic changes affecting the
Airway

Deposit of adipose tissue in the lateral
pharyngeal walls

Deposit of adipose tissue external to the upper
airway

Presence of hypopharyngeal adipose tissue

Presence of pretracheal adipose tissue

Alteration in the shape of the pharynx(long axis
of ellipse transverse to ellipse ant- post)

↓efficiency of the anterior pharyngeal dilator
muscles .

29. Gastrointestinal Changes






Increased acidity and volume of gastric
contents.
Hiatus hernia and gallstones(due to
hypercholestrolemia) are common
Increased intra-abdominal pressure.
There is a higher risk of regurgitation and
aspiration requiring rapid sequence
induction if a difficult airway is not
anticipated.
Fatty infiltration of liver (denoting the
duration of obesity)
Tracheal extubation should be undertaken
with the patient awake

30. Endocrine Changes
There is an association with glucose
intolerance.
 Hypercholesterolaemia
 Hypothyroidism
 Cushing syndrome
 Insulinoma
 tumor involving Hypothalamus
 Metabolic Syndrome and
 PCOD.


31. 
“ Morbidly obese
individuals have
limited mobility
and may therefore
appear to be
asymptomatic even
in the presence of
significant
respiratory and
cardiovascular
impairment.”

32. Morphological Changes
Positioning
 Transferring
 Monitoring (arterial line may be
needed if NIBP is problematic)


33. Surgical and Mechanical
Issues
Reduced surgical access
 Difficult visualisation of underlying
structures
 Excess bleeding
 Longer operating times
 Higher risk of infection
 Wound infection and wound
dehiscence


34. OTHERS
Gout
 Osteoarthritis of weight bearing
joints
 Back pain
 Hepatic impairment/gallstones
 Abdominal herniae
 Breast and endometrial malignancies


35. Preoperative evaluation


36. 





Detailed history
Physical examination
Suspect OSA ( h/o- Snoring).
Examination of calf muscles for tenderness
Examining signs of cardiac failure and
diabetes.(Waist-to-hip ratio >1 in women & >0.8 in
men increases the risk for IHD, Stroke, Diabetes &
Death)
Prior anesthetic records should be obtained.
◦ History of previous surgeries
◦ Anesthetic challenges (i.e. ease or difficulty in securing
the airway, intravenous access)
◦ Need for ICU admission, Surgical outcomes
◦ Weight of the patient at that time.

37. The Upper Airway Assessment








Atlanto-occipital joint extension
Mallampati classification
Temporomandibular joint (TMJ)
assessment with interincisor distance
Mentohyoid distance
Dentition
Pretracheal adipose thickness
Neck circumference
Hypertrophic tonsils and adenoids.

38. Special
attention should
be paid to Circulatory,
Pulmonary, and Hepatic
function

39. Circulatory evaluation







Signs and symptoms of left or right
ventricular failure
Classic physical signs of cardiac failure (e.g.
sacral edema) may be difficult to identify.
History of Hypertension and Diabetes
Blood pressures must be taken with the
appropriate size cuff.
Intravenous and intraarterial access sites
should be checked in anticipation of technical
difficulties
Electrocardiographic abnormalities
Echocardiogram

40. Respiratory evaluation








Smoking history
History of hypoventilation and somnolence
Pulmonary function tests with spirometry
baseline
arterial blood gases
Chest x-ray
Patients with a history of heavy snoring
should have a formal sleep study or
Polysomnogram (PSG).
Severity of obstructive sleep apnea and
hypopnea syndrome (OSAHS), apneahypopnea index (AHI)
Home Oxygen therapy with continuous
positive airway pressure (CPAP) ,response
and compliance should be noted.

41. Hepatic function tests
Serum albumin and globulin
 Serum aspartate aminotransferase
 Serum alanine aminotransferase
 Direct and total bilirubin
 Alkaline phosphatase
 Prothrombin time, and
 Cholesterol levels.


42. Recommended
Preoperative
Laboratory
Evaluations

43. 
Routine investigations

ECG is mandatory

2D-Echo

CXR

X-ray neck

Baseline ABG(will help evaluate carbon dioxide retention
and provide guidelines for perioperative oxygen
administration and possible institution of and weaning from
postoperative ventilation)

Screening for diabetes

LFT

Lipid Profile

PFT (if needed)

Polysomnogram (if history of heavy snoring)

44. Preparation Challenges
for the
Anesthesiologist

45. 








Airway management: Awake fibreoptic intubation
Positioning, Monitoring
Choice of anesthetic technique and anesthetic
agents
Pain control
Fluid management
Consider asking for Assistance.
A typical operating table will support 150 kg, but the
tilting/tipping may not function.
The sphygmomanometer cuff width should be 20%
greater than the diameter of the arm
Invasive blood pressure monitoring may be required

46. Dvt
Heparin, 5000 IU subcutaneously,
administered before surgery and
repeated every 12 h until the
patient will be fully mobile, or low
molecular weight heparins (LMWH)
injected subcutaneously 40 mg
every 12 h resulted in a decreased
incidence of postoperative DVT
complications
 Stockings, Early mobilization.


47. NPO status, and a large bore
intravenous access inserted.
 An experienced Assistant
 The full complement of alternate
airway, noninvasive and invasive (e.g.
cricothyriodotomy set and surgical
tracheotomy set) airway devices
should be available.


48. Monitors

ECG

NIBP
◦ Cuffs with bladders that encircle ideally of 75% or
minimum of 50% of the upper arm circumference should
be used

Invasive BP

Pulse oxymetry

EtCO2

Temperature

Neuromuscular monitoring

Central Venous pressure monitoring

Hourly urine output is evaluated to assess fluid
balance

49. Premedication

50. Preoperative medications

Avoid CNS and respiratory depressants.(sedatives or
narcotics).

Antibiotic prophylaxis; increased risk of postoperative
wound infection

Anticholinergics(Glyco) if awake intubation is planned.

Aspiration
prophylaxis(H2-receptor
antagonists
and
proton pump inhibitors).

Continue antihypertensive medications.

If required O2 supplementation and monitoring.

Premedication should not be given IM as it may be
inadvertently administered into adipose tissue leading
to unpredictable absorption.

51. Positioning

Strapping to the operating table in combination with a
malleable bean bag

Padding of pressure areas

Special tables for extra load (two tables)

The head up reverse trendelenburg position provides
the longest safe apnea period during induction

Lateral tilt to avoid compression of vena cava

52. 
“Stacking” using towels or folded blankets under
the shoulders and the head to compensate for the
exaggerated flexed position of posterior cervical
fat .

The object is to position the patient so that the tip
of the chin is at the higher level than the chest to
facilitate laryngoscopy and intubation.

53. Troop Head Elevation Pillow

55. Anaesthetic management

56. Intubation technique

Anticipate for difficult airway and prepare in
same line

Awake intubation in morbid obese patient
LA  DL  Glottis visualized  GA  intubate
Not visualized Awake intubation
or
Awake fiberoptic
We should be ready for emergency tracheostomy

57. Drug handling in obesity
Unpredictable Volumes of
distribution
 Binding
 Elimination of drugs
 Reduction in total body water
 Higher fat mass
 Higher lean mass
 Higher GFR
 Increased renal clearance


58. PHARMACOKINETICS OF DRUGS

Drugs are dosed in the morbidly obese on the basis of
their lipophilicity.

Highly
Lipophilic
drugs
have
increased
volume
of
distribution so drug doses are calculated on the basis of
the patients Total Body Weight (TBW). Examples are:








Thiopentone
Propofol
Benzodiazepines
Fentanyl
Sufentanyl
Succinylcholine
Atracurium
Cisatracurium

59. 
Weakly lipophilic or lipophobic drugs have unchanged volume of
distribution so drug doses are calculated on the basis of the
patients lean body weight (LBW). Examples are:
 Alfentanil
 Ketamine
 Vecuronium
 Rocuronium
 Morphine sulphate

Certain Lipophilic drugs are adminstered according to LBW are
Digoxin,Procainamide,Remifentanyl((Vd) remain same).

Calculating initial doses based on LBW with subsequent doses
determined by pharmacologic response to the initial dose is a
reasonable approach.

60. Anaesthetic drugs



Insoluble anesthetic gases resistant to
metabolic degradation and without lipid
depot compartmentalization, combined
with rapid return of reflexes are
preferred.
For intubation muscle relaxants with
rapid sequence induction should be
used. Succinylcholine and Rocuronium
are the available choices.
For maintenance of anesthesiaDesflurane/sevoflurane+ Cisatracurium
+intravenous infusion of Remifentanyl is
prefered.N2O should be avoided
particularly in Pt with Pulm HTN.

61. 
Desflurane and Remifentanil
infusion are used for maintenance
anesthetic because of rapid onset,
consistent profile, and rapid offset

62. Extubation Criteria






Intact neurologic status, fully awake and
alert, with head lift greater than 5
seconds
Hemodynamic stability
Normothermia. The core temperature
>36°C.
Train-of-four (TOF) reversal documented
by peripheral nerve stimulator (T4/T1
>0.9).
Full reversal of neuromuscular blocking
agents.
Respiratory rate (>10 and < 30
breaths/minute)

63. 





Baseline Peripheral Oxygenation, as judged by pulse
Oximeter (SPO2 >95% on FIO2 of 0.4).
If an arterial line is present, an arterial blood gas
may be checked.
Acceptable blood-gas results (FIO2 of 0.4: pH, 7.35
to 7.45; PaO2, >80 mm Hg; PaCO2, < 50 mm Hg).
Acceptable Respiratory Mechanics: negative
inspiratory force (NIF) (>25 to 30 cm H2O; vital
capacity (VC) >10 mL/kg IBW; tidal volume (VT) >5
mL/kg ideal body weight [IBW]).
Acceptable Pain Control
No demonstrated or suspected Laboratory
abnormalities

64. Post-operative Considerations
Extubate awake, sitting up.
 ICU care, may need CPAP.
 Oxygen and oximetry.
 Obstructive sleep apnoea is most
common some days after surgery.
 Adequate analgesia to allow deep
breathing/coughing.
 Physiotherapy
 DVT prophylaxis


65. Postoperative analgesia

There is no clear data proving the superiorty of
one technique over other for post op
analgesia.It depends on type ,site , duration,
severity of surgery.
Multi Modal Perioperative Analgesia(MMPA) I,e
preemptive infiltration local anesthetic at the
incision site +NSAIDS+ PCEA(patient controlled
epidural analgesia)/PCIA(patient controlled
intrathecal analgesia) is a new and advanced
method to deal with post op pain.
 In certain situation where sedation is to be
avoided
Dexmedetomidine,Ketorolac,Clonidine,Magnesiu
m sulphate are better alternative of Opoids.


66. Postoperative complications
Postanesthetic hypoxemia
Respiratory depression
Early ventilatory failure with need for
reintubation
 Positional ventilatory collapse
 Hemodynamic instability
 Postoperative nausea and vomiting
(PONV)
 Venous thromboembolism
 Anastomotic leak
 Wound infection.




67. Regional anesthesia

May be impossible
with standard
equipment and
techniques due to;
◦ Obscured landmarks
◦ Difficult positioning
◦ Extensive layers of
adipose tissue
◦

68. Regional Anaesthesia
Engorged extradural
veins and extra fat
constricting the
potential space, less
local anaesthetic 7580% of the normal
dose is needed for
epidurals
 Leave extra catheter
in the space as it may
be subject to drag as
the flexed patient
relaxes.


69. 
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