Repeated thermo‐sterilisation further affects the reliability of positive end‐expiratory pressure valves

Aim Positive end‐expiratory pressure ( PEEP ) valves are used together with self‐inflating bags ( SIB ) to provide a preset PEEP during manual ventilation. It has recently been shown that these valves deliver highly variable levels of PEEP . We hypothesised that material fatigue due to repeated thermo‐sterilisation ( TS ) may contribute to varying reliability of PEEP valves. Methods In a laboratory study 10 new PEEP valves were tested before and after 10, 20 and 30 cycles of routine TS (7 min at 134° C ) by using a neonatal lung model (compliance 0.2 m L /k P a). Settings were positive inflation pressure = 20 and 40  cmH 2 O , PEEP = 5 and 10  cmH 2 O , respiratory rate = 40 and 60/min, flow = 8l/min. PEEP was recorded using a respiratory function monitor. Results Before TS , a mean (standard deviation) PEEP of 4.0 (0.9) and 7.7 (1.0)  cmH 2 O was delivered by the 10 valves when the PEEP was set to 5 and 10  cmH 2 O , respectively. One new valve only delivered 2.0 (0.0) and 5.0 (0.0)  cmH 2 O when the PEEP was adjusted to 5 and 10  cmH 2 O , respectively. Four of the 10 investigated valves showed significant variations in PEEP (coefficient of variation >10%) throughout the autoclaving process. One valve completely lost its function after the 20th TS . Common defects were tears in the softer materials or displacement of the rubber seal. Six of the 10 valves continued to provide PEEP in spite of repeated TS . Conclusion The reliability of PEEP valves is affected by repeated TS . Multi‐use PEEP valves should be tested for reliable PEEP provision following TS .