| Objective Mechanical ventilation (MV) may induce ventilator-induced lung injury (VILI).We studied whether ventilation with different tidal volumes (VT) modified gas exchange and inflammatory response.Method Forty-five patients, ASA class I or II scheduled to undergo an elective laparoscopic surgery were randomly divided into 3 groups. All patients received mechanical ventilation with either tidal volumes of 8 ml/kg, positive end-expiratory pressure (PEEP) of 0 cmH2O, respiration rate(RR) of 10 bpm and inspiratory to respiratory ratio(I:E) of 1:2 after induction of anesthesia. Patients in group I were assigned to MV with either lower tidal volumes of 6 ml/kg and PEEP of 5 cmH2O during pneumoperitoneum,I:E=1:2. Patients in groupⅡwere changed to MV with higher tidal volumes of 10 ml/kg and no PEEP. Patients in group III were assigned as before. RR had been adjusted according to the (PETCO2). After tracheal intubation(T1), at 30 min after LAP(T3), at 60 min after LAP(T4),and breathing air for 10 minutes after extubation and patients having come round(T5), the arterial blood samples were taken for gas analysis. Airway peak pressure(Ppeak), airway mean pressure (Pmean) were recorded with side stream spirometry. Pulmonary dynamic compliance(Cdyn), index of oxygenation(OI), index of respiration(IR),oxygen pressure difference between alveolar and arterial(A-aDO2) were computed according to the arterial blood oxygen partial pressure (PaO2), partial pressure arterial CO2 (PaCO2), inspired oxygen fraction (FiO2), etc.. Drew 4ml venous blood to determine concentrations of Leukocyte interleukin-8 and Tumor necrosis factor-a in the three groups by using enzyme Alliance immune adsorption method (ELISA) respectively at T1, T4, T5 and on postoperation of 24h (T6).Results No significant differences were found on basic data and main arterial pressure,heart rate and PaO2. Ppeak were more elevated after setting pneumoperitoneum than that of T1 (P<0.05).especially of Group II (P<0.05); Pmean of Group I and II were increased at T1, T3 and T5,compared with T1 (P<0.05);Cdyn were decreased significanly during pneumoperitoneum in three groups (P<0.05); PH at T3,T4,T5 were lower than that of T1 (P<0.05); PaCO2 were increased significanly during pneumoperitoneum in group I andⅢ(P<0.05); A-aD02 and IR were obviously decreased after extubation(T5) compared with mechanical ventilation(T1,T3,T4) (P<0.05).Comparisons with groups:Ppeak were decreased significantly in group I compared with those in group II during pneumoperitoneum (P<0.05),however,Pmean were increased significantly in group I (P<0.05);Cdyn were decreased significantly in group II compared with group I at T2 and T4 (P<0.05); PETCO2 of group II were lower than those of group I and III (P<0.05) at T2, however, they were significantly lower than those of group I at T3 and T4 (P<0.05);Compared with group II,PH of group I were decreased obviously at T3 and T4 (P<0.05);A-aD02 were decreased significantly in group I compared with those in group III after extubation (P<0.05), and also the RI. Compare with T1, concentrations of IL-8 and TNF-a at T4 in three groups had no obvious changes (P>0.05).But concentrations of IL-8 and TNF-a at T5 and T6 has increased significantly (P<0.05), and concentrations of IL-8 and TNF-a in group I increased significantly less than these in groupⅢ(P<0.05);At T5 and T6, the concentration of IL-8 in group I was lower than that in groupⅡ(P<0.05).Conclusion Low tidal volume combined with low level of positive end-expiratory pressure for MV, which can reduce the airway peak pressure and pulmonary dynamic compliance during pneumoperitoneum and improve the alveolar oxygenation, could be safely used in laparoscopic surgery. |
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