Managing acute respiratory decompensation in the morbidly obese

Abstract

Morbid obesity adversely affects respiratory physiology, leading to reduced lung volumes, decreased lung compliance, ventilation perfusion mismatch, sleep-disordered breathing and the impairment of ventilatory control, and neurohormonal and neuromodulators of breathing. Therefore, morbidly obese subjects are at increased risk of various pulmonary complications that can present either acutely or chronically. Respiratory failure is one of the most common pulmonary complications related to morbid obesity. Both acute hypoxaemic and hypercapnic respiratory failure are more common among obese patients. The management pathway of respiratory failure depends, to a large extent, on the underlying cause, primarily due to the diversity of the underlying triggering diseases, the pathophysiology and the prognosis associated with each disease. Morbidly obese patients with hypoventilation have an increased risk of acute hypercapnic respiratory failure. Early diagnosis of this disorder and the application of non-invasive ventilation in this group of patients have been shown to improve respiratory parameters, decrease the need for invasive mechanical ventilation and improve survival. Invasive ventilation remains the last life-saving procedure in patients with respiratory failure who do not respond to non-invasive measures. However, due to the abnormal respiratory physiology in obese patients, special precautions are required during intubation, mechanical ventilation and weaning.