The difference In intrapuimonary shunt during one-lung ventilation under general anesthesia with isoflurane or propofol-remifentanil / 中华麻醉学杂志

ABSTRACT

Objective To determine if propofol-remifentanil and isoflurane have any different effects on intrapulmonary shunt during one-lung ventilation (OLV). Methods Twenty-four ASA Ⅰ or Ⅱ patients (18 male, 6 female) aged 42-69 yr undergoing radical esophagus cancer resection via left thoracotomy were randomly divided into 2 equal groups ( n = 8 each) : propofol group (Pro) and isoflurane group (Iso) . The preoperative lung function was normal in both groups. The patients were premedicated with intramuscular diazepam 10 mg and atropine 0.5 mg. Radial artery was cannulated and S-G catheter was placed via right internal jugular vein in pulmonary artery. Anesthesia was induced with propofol 1.5-2.0 mg?kg-1, fentanyl 4 ?g?kg-1 and succinylcholine 1.5 mg?kg-1 and maintained with TCI of propofol and remifentanil (target plasma concentration was set at 3.2 ?g?ml-1 and 4.5 ng?ml-1 ) or isoflurane inhalation ( end- tidal isoflurane concentration = 1.5% -2.5 % ) and intermittent i. v. boluses of fentanyl. The patients were mechanically ventilated after endobronchial intubation with double-lumen tube (VT = 8-10 ml, RR= 10-12 bpm, I:E = 1:2) . During OLV VT was reduced to 6-8 ml and RR increased to 14-16 bpm.PaCO2 was maintained at 35-45 mm Hg. ECG, HR, MAP, SpO2, auditory-evoked potential index (AAI), cardiac index (CI), airway pressure and end-tidal isoflurane concentration were continuously monitored during operation. Blood samples were taken from radial artery and pulmonary artery at 10 min after S-G catheter placement (T0, baseline) at 10 min bilateral ventilation (in right lateral position) (T1) at 15, 30, 60, 90 min of OLV (T2-5) for measurement of blood gases and calculation of Qs/Qt.Results The two groups were comparable with respect to age, M/F ratio, body weight and preoperative lung function. AAI was below 30 during operation and PaCO2 and pH were within normal range in both groups. Qs/Qt was significantly increased while PaO2 was significantly decreased during operation (from T1 to T5 ) as compared to baseline values (T0) but Qs/Qt was gradually decreasing while PaO2 was gradually increasing from T2-5 in both groups. Qs/Qt was significantly lower in Pro group than in Iso group at each interval (T2-5) but there was no significant difference in PaO2 at T2-5 between the two groups. Conclusion There is less intrapulmonary shunt during OLV under general anesthesia with propofol-remifentanil than with isoflurane but the difference is not significant enough to affect PaO2.