The Effects Of PCV Combined With PEEP In Laparoscopic Surgery In PaO₂and PaCO₂

Objective:To investigate the effects on PaCO₂and PaO₂in PCV（Pressure-controlledVentilation） combined with PEEP（Positive end expiratory Pressure） during laparoscopicsurgery.Methods:40cases of laporoscopic surgery,ASA1-2level in which25female,15malecases,aged35to55years，49-70kg.20cases underwent laparoscopic hysterectomy while therest underwent laparoscopic resection of rectal cancer,randomly divided into A and Bgroups.Each group includes20cases.All the cases undergo general anaesthesia withsevoflurane inhalation,remifentanyl and cis-atracurium continued intravenous injection.Afterintubation,all the cases we started with VCV（Volume-controlled Ventilation）,and set TidalVolume（VT） at10ml/kg.At the beginning of pneumoperitoneum,we decreased VT to8ml/kgand recorded maximum airway pressure（Pmax）.We checked arterial blood-gas analysis20minutes after starting pneumoperitoneum.After that, A group was first converted to PCV inwhich inspiratory pressure equal to the Pmax we recorded before.20minutes later,wechecked and recorded arterial blood-gas analysis once more,then returned to theoriginal（VT=8ml/kg）VCV mode,.After another20minutes,we swtiched to PCV combinedwith PEEP mode,We set PEEP to5cmH2O.Now the inspiratory pressure is Pmax werecorded before minus5cmH2O. We checked and recorded the arterial blood-gas analysis athird time.We changed the turns of PCV and PCV combined with PEEP in B group,and weused the same method mentioned above,and recorded the results of the arterial blood-gasanalysis and airway pressure.During pneumoperitoneum, we kept the other respiratoryparameters such as inhalation of oxygen fraction,respiratory rate,inspiratory to expiratoryratio and the Pmax（maximum airway pressure） unchanged.Compared two groups of the three arterial blood-gas analysis （artery oxygen tension,artery CO₂tension and pH value）,andstudied the effects on PaCO₂and PaO₂in PCV combined with PEEP during laparoscopicsurgery.Results:Intraclass:PaO₂in VCV mode were less than mode PCV and mode PCV combinedwith PEEP（P<0.05）,and PaO₂in PCV mode is less than mode PCV combined with PEEP（P<0.05）.PaCO₂in PCV and PCV combined with PEEP mode is less than in VCV mode（P<0.05）,and there was no difference（P>0.05） of PaCO₂in PCV mode and PCV combined withPEEP mode,The pH value in VCV mode was different from that in PCV mode and PCVcombined with PEEP mode（P<0.05）,and there was no difference （P>0.05） in pH valuebetween PCV mode and PCV combined with PEEP mode.Interclass:The general situation ofthe patients of the two groups and the corresponding ventilation monitoring in these threeventilation modes indicated no significant difference（P>0.05）.Conclusion:PaO₂will increase and PaCO₂will decrease when we choose PCV combined withPEEP ventilation mode during laparoscopic surgery.So PCV combined with PEEP is a wellventilation mode that worth recommending.