The Correlation Between PetCO₂ And PaCO₂ During Anaesthesia Of Laparoscopic Surgery

Objective: To investigate correlation between arterial partial pressure of carbon dioxide (PaCO2) and end expiratory partial pressure of carbon dioxide (PetCO2) during anaesthesia of laparoscopic surgery.Methods: 10 ASAⅠorⅡpatient, aged 27～58 years old, weighing 45～74 kg, undergoing laparoscopic surgery were selected. The patients were premedicated with oral diazepam 5mg and intramuscular atropine 0.5 mg. Anaesthesia was induced with midazolam 0.1 mg/kg, sulfentanyl 0.3μg/kg, propofol 1 mg/kg, rocuronium 0.6 mg/kg and remifentanil 1μg/kg. The patients were tracheal intubated and mechanically ventilated. Anaesthesia was maintained with propofol 3-5mg·kg-1·h-1, remifentanil 0.2-0.4μg·kg-1·min-1, and rocuronium intermittently injected 0.15mg/kg. Before pneumoperitoneum the tidal volume was 6-8 ml/kg and respiratory rate was 10-12 times per minute, after pneumoperitoneum the tidal volume was 8-10ml/kg and respiratory rate was 12-16 times per minute. The intra-abdominal pressure (IAP) was maintained at 12-14 mmHg. Arterial blood samples were collected after 10 min of anaesthesia induction(T1)and after 1h of pneumoperitoneum (T2)respectively for blood gas analysis. The values of arterial partial pressure of carbon dioxide (PaCO2) were measured, The values of PetCO2 were recorded at the same time.Results:1 Compared with those before pneumoperitoneum, PaCO2, PetCO2 and Pa-etCO2 were increased after 1h of pneumoperitoneum, Vt and RR need to be increased to keep the PaCO2 in normal.2 Before pneumoperitoneum and after it, Pa-etCO2 were 1.40±1.7192 and 3.51±2.2571 mmHg respectively, coefficient correlation(r)between PaCO2 and PetCO2 were 0.956 and 0.908(P<0.01)respectively, the correlation between PaCO2 and PetCO2 was good.3 Before pneumoperitoneum and after it, there was significant difference in the Pa-etCO2 values with paried-Samples t test (P<0.05).Conclusion:1 PetCO2, PaCO2 and Pa-etCO2 are increased during anaesthesia of laparoscopic surgery, it should be paid more attention to the PetCO2.2 PetCO2 can't replace the artery blood gas analysis during anaesthesia of laparoscopic surgery。...