Objective:
In this study, we aimed to investigate the effects of different oxygen concentrations used in induction and maintanence of anesthesia on pulmonary gas exchange in laparoscopic cholecystectomy which entertain the risk of atelectasis.
Materials and Methods:
After the approval of Ethics Committee of the Institution and informed written consent forms were obtained, 75 patients undergoing elective laparoscopic cholecystectomy aged between 19 to 76 years, were randomized into 3 groups. Preoxygenation was performed with 80 % O2 to low FiO2 groups (Groups A and N) and 100 % O2 to high FiO2 group (Group O) for 3 minutes. After induction and maintenance of anesthesia, patients in Group A ventilated with air + 0,4 FiO2 , Group N with N2 O + FiO2 0,4, and Group O with 1 FiO2 . Patients’ blood gas samples were collected before preoxygenation, 30 minutes after CO2 insufflation, at PACU and 24 hours after the end of surgery. At the same time intervals, PaO2 /FiO2 and P(A-a) O2 values were calculated to evaluate the gas exchange in lungs.
Results:
Baseline PaO2 /FiO2 ratios of patients ventilated with air+FiO2 0,4 were not different when compared with those obtained at 30th min of pneumoperitoneum, PACU, and postoperative 24th hours, respectively. PaO2 /FiO2 ratios of Groups O and N were significantly worsened especially at the 30th min of pneumoperitoneum when compared with the baseline values. Except for the baseline, the highest PaO2 /FiO2 ratios were achieved with 0,4 FiO2 in air at all estimated time intervals (p<0,05) P(A-a) O2 was not significantly different from the baseline value in Groups A and N, whereas in Group O, 24th hour-value was significantly higher than the baseline value (p<0,05).
Conclusion:
Administration of 100 % O2 and N2 O + O2 worsened gas exchange and increased tendency to atelectasis in laparoscopic surgeries, instead, the use of air + 0,4 FiO2 mixture did not exert a negative impact on the development of atelectasis.
Keywords: General anesthesia, laparoscopy, absorption atelectasis, oxygen