Physiological Effects Of Permissive Hypercapnia During Gynecological Laparoscopic Operation

Objective: To observe physiological effects of permissive hypercapnia(PHC) in gynecological laparoscopic operation and decide extensive use of this ventilation strategy.Methods: 36 cases underwent gynecological laparoscopic operation were divided randomly into two groups: a hypercapnic group (n=18) and a normocapnic group (n=18). ASA Ⅰgrade. During operation the intra-abdominal pressure was kept 1.73～1.87kPa. Two groups' ventilation parameters were VT 7～8ml/kg, RR 12breaths/min and I:E = 1:1.5 to maintain PaCO2 at 35～45mmhg(4.6～6.0kPa)before CO2 pneumoperitoneum(PP). Normocapnic group VT during PP were more than 10ml/kg to keep PaCO2 at normal level while hypercapnic group's ventilation parameters were not changed to permit PaCO2 increase to some extent. ECG, BP, HR, SpO2, PETCO2, PIP, Pmean and MV were observed and blood samples were taken before PP, at 20, 40 min during PP and 5min after deflating.. Qs/Qt calculated according to PaO2 and PaCO2. The time of postoperative tracheal extubation and consciousness were recorded. Result: Circulation changes were same in two groups. VT and MV in hypercapnic group were lower than those in normocapnic group (P＜0.01) while Pmean and PIP in normocapnic group were higher than those in hypercapnic group(P＜0.01). PaO2, HCO3-, BE and Qs/Qt were not changed significantly during PP compared with those before PP.Conclusions: Tide volume and airway pressure were significantly decreased during PP with PHC to prevent barotrauma and volutrauma without much physiological effects on patients.