Positive end-expiratory pressure increases arterial oxygenation in elderly patients undergoing urological surgery using laryngeal mask airway in lithotomy position

Elderly patients undergoing urological surgery in the lithotomy position may be vulnerable to perioperative hypoxemia. Positive end-expiratory pressure (PEEP) can improve arterial oxygenation. Although laryngeal mask airway (LMA) is widely utilized in urological surgery, it is not known how PEEP affects arterial oxygenation in these patients. We, therefore, evaluated the effect of PEEP on arterial oxygen partial pressure (PaO 2 ) in elderly patients using LMA during urological surgery in the lithotomy position. Patients randomly received zero end-expiratory pressure (group Z, n = 34) or PEEP of 7 cmH 2 O (group P, n = 33). Ventilatory, respiratory, and haemodynamic variables were measured at 5 min (T0), 30 min (T1), and 60 min (T2) after LMA Supreme™ (sLMA) insertion. The primary outcome was the difference of PaO 2 at T2 between the two groups. Atelectasis score, the incidence of a significant leak, and complications associated with sLMA insertion were also evaluated. PaO 2 at T2 was significantly higher in group P than in group Z (20.0 ± 4.9 vs. 14.7 ± 3.7 kPa, P < 0.001). Atelectasis score at T2 was lower in group P than in group Z (5.3 ± 1.7 vs. 8.4 ± 2.3, P < 0.001). However, the incidence of a significant leak and complications associated with LMA insertion did not significantly differ between the two groups. PEEP can improve arterial oxygenation and reduce atelectasis in elderly patients using sLMA during urological surgery in the lithotomy position, suggesting that PEEP may be useful for elderly patients with an increased risk of perioperative hypoxemia when using sLMA.