1.23 Morbid Obesity

Question 1

PreOp assessment

Answer 1

Accurate BMI calculation
measurement
lifestyle advise diet exercise and smoking

Appropriate Hx and Exam
Invx ID + optimise comorbs

Awareness higher risk comorbs

Question 2

CVS

Answer 2

HTN
Dyslipadaemia
IHD
CMyopathy
HFail

VTE
require preop pharm + mech prophylaxis

ECG
risk arrh
- hypertrophy / ?hypoK - diuretics / IHD / OSA

Consider CXR ABG Echo CPET Stress testing

Question 3

Resp

Answer 3

OSA
Cor pulmonale
soboe 
obesity hypovent syndrome
?prop CPAP

Thorough airway assessment and ability lie supine

Question 4

GI + Endocrine failure

Answer 4

Risk gord reflux - ?antacid

Diabetes + a/w complications
renal / autonomic cardiac
HBA1c

Question 5

Intraoperative Mx

Airway

Answer 5

Appropriate equipment
Back up plan

May be difficult
fat + positioning
Allowance for potential aspiration risk ?rsi

Positioning
FRC and closing volume
shorter time to apnoeic desat
during induction and instrumentation

PreO2
semi recumbent or sitting
Ramping can improve position
oxford pillow

Safety first ?AFOI

Question 6

Respiratory

Answer 6

Prone to desat:
1. Shunting

2. Hypoventilation
3. FRC decrease
   abdo splint of diaphragm
4. Decrease chest wall and diaphragmatic tone
5. Less central control hypoxia and hypercarb

Difficulty in ventilation because of high peak airway pressure

Use short acting drugs recommended
risk Postop hypoventilation and hypoxia

Question 7

Other

Answer 7

1. Induction on OT
   reduce manual handle
   hover mattress for transfer - protect staff
2. Choose appropriate size bp cuff
   ?invasive - inaccuracies
3. CVC ?iv access difficult
4. Alter drug doses according
   - Ideal body weight for fat soluble drugs
   Barbiturate / bzd

• Lean body mass for water soluble NDMB
• Reduce LA doses central neuraxial
  engorged vessel / increased fat content

5. Maintain glycaemic control
   Insulin infusion
6. Regional
   May be difficult or impossible
   d/t subcut tissue
   even w/ US