Figure 59-4 A modified Ayres T-piece that allows positive end-expiratory pressure and has a "pop-off" to reduce the likelihood of a pneumothorax. (Adapted from Gregory GA, Kitterman JA, Phibbs RH, et al: Treatment of the idiopathic respiratory-distress syndrome with continuous positive airway pressure. N Engl J Med 284:1333, 1971.)