SAQ 281 – Airway – bariatric respiratory failure and rapid sequence intubation

Airway – bariatric respiratory failure and rapid sequence intubation.

a. ABG calculations and interpretation

• Expected HCO3 for chronic respiratory acidosis: approximately 51 mmol/L.
• Calculated A-a gradient is negative/bizarre at approximately -43 mmHg, possibly because supplemental oxygen was given before sampling.
• Expected A-a gradient for age: approximately 19 mmHg.
• There is an acute type 2 respiratory failure/acute respiratory acidosis superimposed on chronic respiratory acidosis, with metabolic alkalosis.

b. Obesity-related RSI effects

• Upper-airway resistance and difficult bag-mask ventilation.
• Pharyngeal soft-tissue crowding and poor landmarks.
• Reduced functional residual capacity and rapid desaturation.
• Reduced chest-wall compliance and higher ventilation pressures.
• Ventilation-perfusion mismatch and airway closure.
• Reduced venous return or right-heart disease.
• Increased gastric volume, reflux, and aspiration risk.

c. First-pass success

• Use a ramped position with external auditory meatus aligned to the sternal notch.
• Use NIV for preoxygenation and nasal-prong apnoeic oxygenation.
• Use video laryngoscopy and appropriate drug dosing.

d. Improve oxygenation

• Withdraw and reposition the endotracheal tube above the carina.
• Increase FiO2 to 1.0.
• Position the patient at approximately 45 degrees.
• Ensure adequate sedation and paralysis.
• Use pressure-controlled ventilation and a graded recruitment manoeuvre with adequate PEEP.