ABSTRACT
Hypoxia is a concomitant of atelectasis because of the mechanical forces that predispose to low ventilation/perfusion (V/Q) matching. The absence of nitrogen in the patient breath ing an Fio2 of 100% does not appear to be a major contributor to atelectasis. Those most susceptible to hypoxia are the aged, the obese, and those with preexisting lung disease whose propensity for airway closure and low V/Q areas predate the additional insults of anesthesia.
