Influence of different positive end-expiratory pressure on oxygenation and pulmonary shunt fraction during one-lung ventilation

Objective To study the different positive end-expiratory pressure(PEEP) on pulmonary shunt fraction and oxygenation during one-lung ventilation(OLV),and to explore the best PEEP value in OLV.Methods Thirty patients with ASA Ⅰ-Ⅱ level elective thoracotomy with OLV were selected.The blood gas analysis were performed in the lateral position at ventilation 30 min(T1),OLV 30 min(T2),5 cmH2O OLV PEEP 30 min(T3),and 10 cmH2O OLV PEEP 30 min(T4).At each time point,the PaO2,PaCO2,SaO2,pH,HR,mean arterial pressure(MAP),and peak airway pressure(Ppeak) were recorded,and the intrapulmonary shunt(Qs / Qt) was calculated.Results Compared with two-lung ventilation,the PaO2 was decreased and the Qs / Qt was increased significantly(P0.05),the PaO2 was increased from(200.20 ± 145.25) mmHg to(299.55±138.83) mmHg(P0.05) and the Qs / Qt was decreased(P0.05) at the duration of T2 to T3;the PaO2 was decreased from(299.55 ± 138.83) mmHg to(237.30 ± 135.57) mmHg(P0.05) and the Qs / Qt was increased(P0.05) at the duration of T3 to T4;the Ppeak value was increased from T2(21.15±3.60) cmH2O to T4(27.20±3.78) cmH2O(P0.05) in OLV.Conclusion During OLV,5 cmH2O PEEP applied in ventilated lung can increase the PaO2,decrease the Qs / Qt and prevent the occurrence of hypoxemia.It is more appropriate PEEP value.