Effects of Positive End-Expiratory Pressure on Pulmonary Oxygenation and Biventricular Function during One-Lung Ventilation: A Randomized Crossover Study

Abstract

Although the application of positive end-expiratory pressure (PEEP) can alter cardiopulmonary physiology during one-lung ventilation (OLV), these changes have not been clearly elucidated. This study assessed the effects of different levels of PEEP on biventricular function, as well as pulmonary oxygenation during OLV. Thirty-six lung cancer patients received one PEEP combination of six sequences, consisting of 0 (PEEP_0), 5 (PEEP_5), and 10 cmH₂O (PEEP_10), using a crossover design during OLV. The ratio of arterial oxygen partial pressure to inspired oxygen fraction (P/F ratio), systolic and diastolic echocardiographic parameters were measured at 20 min after the first, second, and third PEEP. P/F ratio at PEEP_5 was significantly higher compared to PEEP_0 (p = 0.014), whereas the P/F ratio at PEEP_10 did not show significant differences compared to PEEP_0 or PEEP_5. Left ventricular ejection fraction (LV EF) and right ventricular fractional area change (RV FAC) at PEEP_10 (EF, p < 0.001; FAC, p = 0.001) were significantly lower compared to PEEP_0 or PEEP_5. RV E/E' (p = 0.048) and RV myocardial performance index (p < 0.001) at PEEP_10 were significantly higher than those at PEEP_0 or PEEP_5. In conclusion, increasing PEEP to 10 cmH₂O decreased biventricular function, especially on RV function, with no further improvement on oxygenation compared to PEEP 5 cmH₂O during OLV.

Keywords: biventricular function; one-lung ventilation; positive end-expiratory pressure; pulmonary oxygenation.

Figure 1

Doppler tissue waves derived from the septal mitral annulus, and time intervals required for calculation of myocardial performance index. E’, peak early diastolic mitral annular velocity; A’, late diastolic mitral annular velocity; S’, peak systolic mitral annulus velocity; ICT, isovolumic contraction time; IRT, isovolumic relaxation time; ET, ejection time; MPI, myocardial performance index.

Figure 2

Flow chart of patient enrollment. VATS, video-assisted thoracoscopic surgery.

Figure 3

Effects of positive end-expiratory pressure on the changes of arterial oxygen partial pressure (PaO₂, A), the ratio of arterial oxygen partial pressure to inspired oxygen fraction (P/F ratio, B). * p < 0.05 versus PEEP_0.

Figure 4

Effects of positive end-expiratory pressure on the changes of cardiac function. (A) LV EF, left ventricular ejection fraction; (B) RV FAC, right ventricular fractional area change; (C) LV MPI, left ventricular myocardial performance index; (D) RV MPI, right ventricular myocardial performance index. * p < 0.05 versus PEEP_0, † p < 0.05 versus PEEP_5.