Effects of desflurane anesthesia depth on intrapulmonary shunt during one-lung ventilation

【Objective】 To study the effects of different concentration of desflurane on hypoxic pulmonary vasoconstriction (HPV) during one-lung ventilation (OLV). 【Methods】Thirty-six patients, ASA Ⅰ or Ⅱ, scheduled for selective left thoracotomy, were randomly divided into three groups: group P (n=12), group D-1 (n=12) and group D-2 (n=12). Anesthesia was induced with intravenous midazolam 0.2 mg/kg, fentanyl 4 μg/kg and rocuronium 0.9 mg/kg in group D-1 and D-2, while with intravenous propofol 4 μg/mL, fentanyl 4 μg/kg and rocuronium 0.9 mg/kg in group P. Right-sided double-lumen endobronchial tube (Mallinckrodt) was intubated orally. Then anesthesia was maintained with target-controlled infusion of propofol to keep BIS value between 40 and 49 in group P, or with desflurane 3% and 6% inhalation in group D-1 and D-2, respectively. The other drugs used in all of the three groups for anesthesia maintenance were fentanyl and rocuronium. MAP and HR were monitored during the whole procedure. Arterial and mixed venous blood samples were taken for blood gas analysis and intrapulmonary shunt calculations before surgery, 15 min after two-lung ventilation (TLV), 15 min and 30 min after OLV in all of the three groups, respectively. 【Results】 After OLV, Qs/Qt increased to over 30% in group D-2. The increase in Qs/Qt of group D-2 was 70.6% greater than that of group D-1 (P＜0.05). The decrease in PaO2 was over 40% following OLV in all of the three groups (P＜0.01). 【Conclusion】 1MAC of desflurane significantly inhibits HPV during OLV, while 0.5 MAC of desflurane affects it slightly.