Abstract
Systemic oxygen delivery (DO(2)) is a more comprehensive marker of patient status than arterial oxygen saturation (SaO(2)), and DO(2) in the range of 330-500 mL min(-1) is reportedly adequate during anaesthesia. We measured DO(2) during one-lung ventilation (OLV) for thoracic surgery-where the risk of pulmonary shunt is significant, and hypoxia occurs frequently-and compared sevoflurane and propofol, the two most commonly used anaesthetics in terms of DO(2). Sevoflurane impairs hypoxic pulmonary vasoconstriction. Thus, our hypothesis was that propofol-based anaesthesia would show a higher DO(2) value than sevoflurane-based anaesthesia. This was a double-blinded randomised controlled trial conducted at a university hospital from 2017 to 2018. The study population consisted of patients scheduled for lobectomy under OLV (N = 120). Sevoflurane or propofol was titrated to a bispectral index of 40-50. Haemodynamic variables were measured during two-lung ventilation (TLV) and OLV at 15 and 45 min (OLV15 and OLV45, respectively) using oesophageal Doppler monitoring. The mean DO(2) (mL min(-1)) was not different between the sevoflurane and propofol anaesthesia groups (TLV: 680 vs. 706; OLV15: 685 vs. 703; OLV45: 759 vs. 782, respectively). SaO(2) was not correlated with DO(2) (r = 0.09, p = 0.100). Patients with SaO(2) < 94% showed adequate DO(2) (641 ± 203 mL min(-1)), and patients with high SaO(2) (> 97%) showed inadequate DO(2) (14% of measurements < 500 mL min(-1)). In conclusion, DO(2) did not significantly differ between sevoflurane and propofol. SaO(2) was not correlated with DO(2) and was not informative regarding whether the patients were receiving an adequate oxygen supply. DO(2) may provide additional information on patient status, which may be especially important when patients show a low SaO(2).