The document presents a detailed case study of a 57-year-old male patient with obesity and obstructive sleep apnea, scheduled for open cholecystectomy. It outlines his medical history, clinical examination, preoperative investigations, anesthesia management, and postoperative care, emphasizing the importance of addressing obesity-related complications during surgery. Key considerations include airway management, intraoperative monitoring, and postoperative pain management to mitigate risks associated with obesity and sleep apnea.

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Obesity with
hypoventilation
Dr. B.Manisha (PG-3)
Department Of Anaesthesiology
Kamineni Institute Of Medical Sciences

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CASE
A 57 year old male patient, smoker, H/O COPD,
diagnosed with acute cholecystitis, posted for open
cholecystectomy. His BMI is 38kg/m2. He is
treated for OSA with BiPAP with pressure 10cm of
H2O insp/ 7cm of H2O exp for past 7 years.

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PAST HISTORY
• Patient is a k/c/o OSA being treated with bipap.
• No associated comorbidities
• Not a K/C/O diabetes, hypertension, asthma,
tuberculosis, epilepsy, jaundice.
• No past surgical history
• No history of any bleeding tendencies

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PERSONAL HISTORY
 Pt is non vaishya.
 Smoker since 20 years, 15cigarettes/day. Last smoked
3years back. 30Packyears
 Occasional alcoholic since 10years, last taken 2months
back.
 Has H/O snoring, choking at night.
 No h/o breathlessness (METS>4)
 No H/O cough, cold
 Two doses of covid vaccination taken
 Bowel and bladder movements regular
 Mixed diet

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CLINICAL EXAMINATION
• Pt is obese built, hydrated
• Wt:108kgs Ht:168cm BMI:38.3kg/m2
• No signs of pallor ,cyanosis, clubbing, pedal oedema, ascites.
• On airway examination—
• Bilateral nares patent
• Normal cervical spine movement.
• Normal TMJ movement,
• short neck+
• No visible neck swelling
• Trachea is central in position
• Hygenic oral cavity.

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• No loose/ protruding/ missing teeth
• > 3finger breadth mouth opening
• Mallampati grade I
• On spine examination-normal
VITALS :patient was conscious, coherent, cooperative,
well oriented to time, place and person.
Blood pressure-120/80 mm of hg
Pulse rate-84 bpm,regular in rhythm, normal in volume
Respiartory rate: 12cpm
Spo2: 97% on room air
Temperature: afebrile
CVS-S1 & S2 heard
RS- Bilateral air entry present, clear.

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INVESTIGATIONS
COMPLETE BLOOD PICTURE
Hemoglobin – 11.9g/dl
Total leucocyte count-10,300 cells/cu mm
Platelet count-3.6 lakhs
Blood group – “B” POSITIVE
• Bleeding time – 2min 00sec
• Clotting time – 4min 30sec
• PT – 16sec
• APTT – 31sec
• INR – 1.11
• RBS: 128mg/dl
COMPLETE URINE EXAMINATION:
• urine albumin+
• Urine sugars- nil

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LIVER FUNCTION TEST
• Total bilirubin-
1.35mg/dl
• Direct bilirubin-
0.28mg/dl
• AST-34 IU/L
• ALT – 51 IU/L
• ALP- 140 IU/l
• Total Proteins – 7.6
gm/dl
• Albumin-4.6 gm/dl
• A/G ratio – 1.56
RENAL FUNCTION TEST
• UREA- 20 mg/dl
• CREATININE – 0.8
mg/dl
• URIC ACID – 5.9 mg/dl
• SODIUM-139 mEq/L
• POTASSIUM – 4.2
mEq/L
• CHLORIDE – 99 mEq /L
• CALCIUM (ionized)- 1.06
• PHOSPHOROUS – 3.1
mg/dl

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ECG

11. • ABG on room air:
PH:7.35
PO2:80mmhg
Pco2:45mmhg
Hco3-:25mmol/L

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• Case was taken under ASA grade 3
PRE-OP VITALS: at 8:30am
• BP: 120/70 mm Hg
• PR: 110bpm
• Spo2: 97%on RA
• Grbs:110mg/dl
• CVS: S1 & S2 heard, no murmur
• RS: B/L air entry present and clear, no added sounds.
I.V Line: 18G IV cannula secured and fixed on the
dorsum of left hand.

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• Patient was shifted to Operation Theatre by
9.10am
• ANTICIPATED DIFFICULT INTUBATION WAS
expected; and RAMP Position was kept.
• PREMEDICATION
INJ. GLYCOPYRROLATE 0.2 mg IV
INJ. ONDANSETRON 4mg IV
INJ. MIDAZOLAM 1mg IV
INJ. FENTANYL 100mcg IV
• Induced with INJ. PROPOFOL 150 mg IV
• Intubation was done using INJ.
Succinylcholine 100mg IV at 9:30 am

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• Intubation done, it was cormack lehanne
grade 2b; was able to pass bougie with 7mm
ENDOTRACHEAL TUBE fixed @ 20cm lip
mark. At 9.45 am
• Confirmed by 5point auscultation and
capnography.
• Ryles tube was inserted
INJ. HYDROCORTISONE 200mg IV

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VENTILATOR SETTINGS: mode: volume controlled
ventilation
Tidal Volume: 6ml/kg
Respiratory rate: 12-16cpm
PEEP: 10cmH2O, I:E ratio- 1:3
Maintainance:
MUSCLE RELAXANT: loading dose: Inj. VECURONIUM 6mg
IV given followed by 9mg given intermittently at intervals.
ISOFLURANE at 0.5-1.5%;
Blood loss: 300ml; urine output: 500ml

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TIME BLOOD
PRESSURE
PULSE RATE SPO2 ETCO2
9AM 120/80 88 100 -
9.30AM
(at the time of
intubation)
150/95 95 100 30
10AM 145/90 92 100 42
10.30AM 140/95 90 99 44
11AM 130/85 86 100 49
11.30AM 120/75 82 100 47
12PM 118/70 80 100 45
1PM 110/68 82 100 43

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• EXTUBATION: after thorough ryles tube,oral, and
ET tube suctioning was done and after adequate
eye opening, tongue protrusion, head lift, muscle
power and tidal volume is attained
REVERSAL: INJ. SUGAMMADEX 400mg IV given at
12:45 pm.
Patient was hemodynamically stable and extubated
at 1pm, and shifted to postop.
POST OP vitals: at 1:20pm
BP:130/90mmhg
Pulse:88 bpm
SPO2:99% with 6litres of 02

19. OBESITY
• Obesity Is defined as an abnormally high
amount of adipose tissue compared with
lean muscle mass (20% or more over ideal
body weight)
• Primarily induced and sustained by an over
consumption or under utilization of
caloric substrate.
• Genetic, behavioral, cultural and
socioeconomic factors.

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Cardiovascular system

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RESPIRATORY SYSTEM
• Restrictive lung disease
• Obesity hypoventilation syndrome (OHS)
• Obstructive sleep apnea (OSA)
• Pulmonary Hypertension

25. RESTRICTIVE LUNG DISEASE
• FRC , ERV, TLC ---- v/q mismatch and arterial hypoxemia(low
pao2)
• Right(deoxy) to left(oxy) intrapulmonary shunting is seen.
• Closing capacity> FRC
• FRC decreases by 50% in obese under GA (20% in non
obese patinets)
• Low FRC--- low O2 reserve--- early desaturation during
apnea
• BMI –-- raised metabolic rate in obese –-- increased O2
utilisation and co2 production–-- raised minute ventilation
and work of breathing

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Terms for describing pt’s weight:-
• Total body weight:- The actual wt. of the pt.
• Ideal body weight:- What the patient should weigh with a
normal ratio of lean to fat mass. Calculated by Broca’s index
IBW(kg)=Ht.(cm) – x (where x=105 in females and 100 in males).
• Lean body weight:- The pt’s wt. excluding fat.
LBW(kg)= 9270 x TBW(kg) . ( 216 for men and 244
for women) 6680+(216/244 x BMI (kg/m2)
• Adjusted body weight:- calculated by adding 40% of the
excess weight to the IBW ABW(kg)= IBW(kg) + 0.4 {TBW
(kg) – IBW (kg)}

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Measuring Scales for obesity
• Body mass index (Quetelet's index)
=[weight(kg)/height(m2)]

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Other parameters:
• Waist circumference:- correlates with
abdominal fat.
High risk: Male > 102 cm, Female > 88cm.
• Waist to hip ratio:-
High risk: >1 in males, >0.8 in females.

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Obstructive sleep apnea
• Episodic Complete cessation of airflow lasting > 10seconds occuring
for > 5 times/hour of sleep accompanied with decrease of atleast 4%
in SaO2.
• Clinical sequelae such as hypoxia, hypercarbia, pulmonary and
systemic hypertension, polycythemia, arrhythmias, risk of IHD and
↑
stroke, corpulmonale.
• Diagnosis:- polysomnography (apnea-hypopnea index)
• Other parameters:- Total arousal index, Respiratory disturbance
index
• Patients diagnosed to have moderate/ severe OSA have to undergo
CPAP prior to elective surgery

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Obesity hypoventilation syndrome
/Pickwickian syndrome
• Results from long term OSA
• Combination of obesity and chronic hypoventilation that
ultimately results in pulmonary hypertension and cor
pulmonale.
• Diagnosis:- BMI >30kg/m2 and awake arterial
hypercapnia (PaCO2 >45mm Hg) in the absence
of known causes of hypoventilation.

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Metabolic syndrome
• Diagnosis:- 3 of the following
– Abdominal obesity (Waist > 102“ in males and > 88“ in
females)
– Hypertension (>130/85 mm Hg)
– Triglycerides ( > 150mg/dl)
– HDL Cholestrol ( <40 mg/dl in males and <50 mg/dl in
females)
– Impaired fasting glucose ( > 110 mg/dl)

34. ANESTHETIC MANAGEMNET

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Preoperative considerations
• PAC:-evaluation of cardiopulmonary system: chest pain,
dyspnea, palpitations, fatigue, syncope, h/o OSA.
• STOP BANG: Sleep Apnea questionnaire
Snoring, Tiredness, Observed apnea, high blood Pressure, BMI
>35, Age >50yrs , Neck circumference >40cm, Gender-male
• High risk of OSA: Yes 5 – 8
• Intermediate risk of OSA: Yes 3 – 4
– Low risk of OSA: Yes 0 – 2
Look for HTN/DM/CCF/pulmonary HTN/OSA
– Symptoms of acid reflux, coughing, if on any antacids?---
GERD

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Concurrent, preoperative, and prophylactic
medications
• Usual medications should be continued except insulin and
OHA.
• Antibiotic prophylaxis
• For aspiration pneumonitis:- H2 receptor antagonists,
nonparticulate antacids, proton pump inhibitors used.
• Nil by mouth – 12 hrs.
• Prophylaxis against DVT.
• Continue CPAP/ BiPAP overnight

37. INTRAOPERATIVE MANAGEMENT

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Positioning
• Specially designed tables or two regular operating tables joined together
• Strapping obese patients to the operating table helps keep them from
falling off the operating table.
• Protecting pressure areas - pressure sores, neural injuries.
• Arms to be kept in neutral position to avoid excess pressure from tight
tucking and draping.
• Choice of anesthesia: Local or regional anesthesia>>> general anesthesia.
• Regional anesthesia:May be difficulty in finding landmarks. Engorged
epidural veins and epidural fat constricting the potential space, 20% less
local anaesthetic of the normal dose is needed.

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GENERAL ANESTHESIA
• PREOXYGENRATION: 30% propped up position; with 100%FiO2,
for 5-8mins with CPAP of 10cm H2O.
• PREMED: avoid benzodiazepines, Sedative-hypnotic in minimal doses
• Emergency airway cart should be kept ready
• If a difficult intubation is anticipated, awake intubation is a
prudent approach.
• Sedation with Dexmedetomidine provides adequate anxiolysis
and analgesia without respiratory depression.
• Hypoxia and aspiration of gastric contents should be prevented.
• Call for an experienced assistant.

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RAMP (RAPID AIRWAY
MANAGEMNT POSITION)
• To align
oral/pharyngeal/lary
ngeal axis

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Maintenance
– Continuous infusion of a short-acting intravenous agent, such as Propofol,
Inhalational agents that are minimally metabolized are useful agents, with
Desflurane possibly providing better hemodynamic stability and faster
washout.
• Avoid N2O as it can worsen pulmonary hypertension Short-acting
opioids, combined with a low-solubility inhalation agents, facilitate a
more rapid emergence without increasing opioid-related side effects.
• Cis-atracurium possesses an organ-independent elimination profile
and is a favorable NDMR for use during maintenance.
• Dexmedetomidine with sedative and analgesic properties, is an
attractive anesthetic adjunct in obese patients.

42. Highly lipophilic drugs----> increased Vd
in obese pt. so drug doses are calculated on
basis of TBW. (eg thiopental, BZDs,
propofol, fentanyl, Sch, dexmedetomidine,
atracurium etc.)
Weakly lipophilic drugs have unchanged
Vd in obese pt. so drug doses are calculated
on basis of LBW. (eg alfentanyl, ketamine,
morphine, vecuronium, rocuronium).

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Intra Operative Ventilatory
Management
Avoid lung overdistension
Use tidal volume of 6-10 mL/kg of ideal body weight
BMI >40 – use mean airway pressure 55cm H2O
BMI <40– use mean airway pressure 40cm H2O. Use PEEP (10-12
cm/H2O)
Consider mild permissive hypercapnia if necessary
Maintain lung recruitment: sigh/valsalve/high tidal volume for 7-
8sec

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Monitoring
• For NIBP, larger bp cuffs should be used
• Invasive arterial pressure monitoring may be indicated for
the morbidly obese, or if inadequate BP cuff.
• USG guided Central venous catheterization may also be
required for difficult intravenous access.
• Prophylactic IVC filter: high risk for DVT, PE
• Maintain normothermia
• For longer duration surgery/morbid obese : with pulmonary
HTN, RVF: consider pulmonary artery catheter/ TEE.

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EXTUBATION
• Patient should be fully awake, follow oral commands, have
adequate muscle strength, Adequate tidal volume and airway
reflexes.
• Neuromuscular monitoring for muscle strength
• Extubate in propped up >30 degrees position
• Shift to PSV+PEEP
• Placement of airway exchange cathetrer before extubation in high
risk cases.
• Insert nasopharyngeal airway
• Supplemental oxygen should be administrated after extubation.

46. Management of postoperative pain
• In patients with obstructive sleep apnea – opioid sparing techniques help
avoid respiratory complications.
• A multimodal approach is best. It include
1. Peripheral and central nerve block with continuous infusion of LA +
opioids
2. NSAIDs , acetaminophen
3. α2 agonists, NMDA receptor antagonists(ketamine), sodium channel
blockers
4. Local anesthetics injected into the wound or port site,
Recent technique is the continuous intraperitoneal infusion of bupivacaine.

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• There is an increased incidence of atelectasis in postoperative
period.
• Initiation of CPAP ------>  FRC, improve lung compliance,
improve ventilation & oxygenation, upper airway obst & 
WOB
• early ambulation, deep breathing exercises, and incentive
spirometry are all useful adjuncts.
• Pulse oximetry and ABG should be monitored appropriately.

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