Fig. 4.
Representative polysomnography recordings of an obese patient before and immediately after bariatric surgery. Respiratory recordings obtained through polysomnography in an obese patient. The first frame shows severe desaturations during sleep at patient’s baseline prior to surgery resulting from a combination of obstructive and central events. In the second frame, immediately following surgery, patient was placed on 30% oxygen in the postanesthesia care unit and continues to have sleep-disordered breathing with mostly central apneas and desaturations. In the third block, again, immediately following surgery, patient was placed on 30% oxygen with continuous positive airway pressure (CPAP) at 10 cm H2O and there were no more apnea or desaturation events. Flow = respiratory flow; Thorax = thoracic respiratory effort; Abdomen = abdominal respiratory effort; Sum = respiratory effort of thorax and abdomen; SpO2 = oxygen saturation; N1 = non-rapid eye movement (REM) sleep stage 1; red bar indicates obstructive apnea; blue bar indicates mixed apnea; pink bar indicates obstructive hypopnea; gray bar indicates desaturation; PACU = postanesthesia care unit.