ABSTRACT
The term morbid obesity refers to obesity that is severe enough to produce symptoms and complications. Patients with the obesity-hyperventilation syndrome (OHS) have all of the features of morbid obesity with comparable degrees of excess body weight, but OHS patients also have ventilatory failure that is frequently complicated by pulmonary hyper tension and right ventricular failure. The diagnosis of OHS is established by demonstrating elevation of the partial pressure of carbon dioxide in arterial blood (PaCo2) in the absence of other causes of C 0 2 retention, such as coexistent chronic obstructive pulmonary disease (COPD). Morbidity and mortality are higher in OHS than in simple obesity. Both simple obesity and OHS are characterized by significant abnormalities of pulmonary gas ex change, respiratory mechanics and pulmonary function, dyspnea on exertion and decreased exercise capacity, and a predilection for obstructive sleep apnea (OSA). Morbidly obese patients are also at risk for developing postoperative complications such as pneumonia, hypoxemia, and atelectasis.
