Systemic Oxygen Delivery during One-Lung Ventilation: Comparison between Propofol and Sevoflurane Anaesthesia in a...

Systemic oxygen delivery (DO₂) is a more comprehensive marker of patient status than arterial oxygen saturation (SaO₂), and DO₂ in the range of 330-500 mL min^-1 is reportedly adequate during anaesthesia. We measured DO₂ 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 DO₂. Sevoflurane impairs hypoxic pulmonary vasoconstriction. Thus, our hypothesis was that propofol-based anaesthesia would show a higher DO₂ 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 DO₂ (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). SaO₂ was not correlated with DO₂ (r = 0.09, p = 0.100). Patients with SaO₂ < 94% showed adequate DO₂ (641 ± 203 mL min^-1), and patients with high SaO₂ (> 97%) showed inadequate DO₂ (14% of measurements < 500 mL min^-1). In conclusion, DO₂ did not significantly differ between sevoflurane and propofol. SaO₂ was not correlated with DO₂ and was not informative regarding whether the patients were receiving an adequate oxygen supply. DO₂ may provide additional information on patient status, which may be especially important when patients show a low SaO₂.