ABSTRACT
INTRODUCTION There is substantial evidence to suggest that obesity is associated with an increased incidence of perioperative complications ( 1-6 ) such as wound infections and breakdown (3) , venous thromboembolism (4) , adverse cardiac events (5) , and respiratory complications ( 7 , 6 ). The mechanisms by which obesity may increase the incidence of perioperative respiratory complications have not yet been completely elucidated. Obese patients breathe rapidly and shallowly, and 80% of morbidly obese middleaged subjects report shortness of breath while climbing two fl ights of stairs (8) . Obese patients also have a higher incidence of diffi cult mask ventilation, airway obstruction, major oxygen desaturation, and overall critical respiratory adverse events ( 2 , 9 ). This chapter aims to provide some insight into the mechanisms by which obesity may affect the upper airway and pulmonary function. Obesity can alter respiratory physiology by two main mechanisms: effects of excessive tissue on upper airway and pulmonary function, and effects of obesity on neurologic control of upper airway dilator and respiratory muscles.
