1. The airway in obese patients

2. Pulmonary physiology Diminished lung capacity
Diminished vital capacity
Decreased chest wall compliance
Increased abdominal cavity contents
Increased airways resistance
Relative room air hypoxia and hypercapnia
VQ mismatch from collapse of small airways
Decreased FRC
Increased O2 consumption and CO2 production

3. Resulting in: Decreased Oxygen Reserve
Rapid desaturation during periods of apnoea

4. Gastrointestinal physiology
Increased intra abominal pressure
Hiatus hernias
Reflux
Larger gastric volume
Lower pH of gastric contents
INCREASED RISK OF ASPIRATION AND LUNG INJURY POST ASPIRATION

5. Predicting difficult airway
Obesity does not necessarily predict difficult laryngoscopy and intubation - other factors may be more important than BMI
Obesity does reliably predict DIFFICULT MASK VENTILATION
If time allows consider awake intubation by an anaesthetist

6. Preoxygenation
Elevate patient’s head to 25 degrees during preoxygenation prolongs time to desaturation
Preoxygenation with 100% O2 via CPAP at 10cm H2O will give you an extra 1 minute
Consider the use of NIV to avoid intubation
Dangers - increased risk of gastric insufflation and aspiration
Nasal prongs

7. Drugs
Renal blood flow
Volume of distribution
Liver metabolism

8. In general Hydrophilic drugs should be dosed on ideal body weight
Lipophilic drugs should be based on total body weight

10. Positioning
Head and shoulders should be elevated about the chest such at the external auditory canal is level with the sternal notch
Ramped position - multiple folded blankets under head and neck

11. Intubation Limit the number of conventional laryngoscopy attempts to 3
Consider other advanced airway techniques
Video laryngoscopy
Bougie
Supraglottic devices

12. Surgical airway
Landmarks obscured by excessive soft tissue and a short neck
Longer tracheostomy tube with more acute angle
Size 6 ETT
Under ideal circumstances cricothyroidotomy requires greater than 100 seconds to achieve ventilation

13. Mechanical ventilation
Respiratory mechanics and gas exchange impaired
Lung volumes should be based on ideal body weight (often overestimated)
PEEP 10
Reverse Trendelenburg