Effects of positive end-expiratory pressure ventilation guided by pressure-volume curve on cerebral blood flow of patient undergoing gynecological laparoscopic surgery in lithotomy position

Objective To observe the effects of positive end-expiratory pressure ventilation guided by pressure-volume curve on cerebral blood flow of patients undergoing gynecological laparoscopic surgery in lithotomy position. Methods Fifty patients( ASA I ~ II) scheduled to undergo gynecological laparoscopic surgery under general anesthesia were randomly divided into two groups( using random number table,n = 25) :control group( Group A) and P-V curve group( Group B). Before pneumoperitoneum,the tidal volume( VT)of all patients was set as 8 ml /kg,respiratory rate( RR) 12 times /min,and respiratory ratio 1: 2. After pneumoperitoneum,patients in Group A maintained the previous parameters,while patients in group B were adjusted as follow: PEEP( PLIP + VT) of 6ml /kg,RR of 18 times /min. End-tidal partial pressure of CO2( P ET CO2),peak airway pressure the( Ppeak),and mean airway pressure( Pmean) were measured,heart rate( HR) and mean arterial pressure( MAP) were monitored and recorded; samples of right radial artery and right internal jugular vein were obtained to measure arterial oxygen pressure( PaO2),arterial carbon dioxide partial pressure( PaCO 2),internal jugular venous blood oxygen partial pressure( PjvO 2),internal jugular venous oxygen saturation( SjvO 2),and jugular vein oxygen content( CjvO 2),and the arterial-internal jugular venous blood gas oxygen content( Ca-jvDO 2) was calculated according to Fick's formula before pneumoperitoneum( T 0),30 min( T1) and 60 min( T 2) after pneumoperitoneum. Results In paired comparisons,compared with T0,the MAP,HR,Pmean,Ppeak,P ET CO 2,PaCO 2,PjvO 2,SjvO 2,and CjvO 2 of two groups at T1and T2 were significantly increased( P 0. 05),while PaO 2 and Ca-jvDO 2 were significantly reduced( P 0. 05). P ET CO 2, Pmean,PaCO 2,and SjvO 2 of group B at T1 and T2 were significantly higher than those of group A( P 0. 05),while Ppeak significantly reduced( P 0. 05),and so did Ca-jvDO 2 of group B at T 1. Conclusions Positive end-expiratory pressure ventilation with low tidal volume guided by pressure-volume curve can improve the cerebral blood flow,balance of cerebral oxygen supply,and demand of patients undergoing gynecological laparoscopic surgery in lithotomy position.