Abstract
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.
Highlights
The concept of systemic delivery of oxygen (DO2) is attracting increasing interest in both the context of anaesthesia [1] and the intensive care unit (ICU) [2,3,4]
An attending anaesthesiologist who was not involved in the study opened the sealed envelope just before induction of anaesthesia and provided the designated anaesthetic agents according to the group assignment
There was no difference in SaO2 between the sevoflurane and propofol groups (TLV: 98.8% vs. 98.8%, respectively; OLV15: 97.7% vs. 97.8%, respectively; OLV45: 97.4% vs. 97.8%, respectively; all, p > 0.05) (Table 2)
Summary
The concept of systemic delivery of oxygen (DO2) is attracting increasing interest in both the context of anaesthesia [1] and the intensive care unit (ICU) [2,3,4]. Sevoflurane and propofol, the two most common anaesthetics, have been compared in terms of SaO2, but not in terms of DO2, during OLV [9]. These anaesthetics may show different associations with DO2, based on their differential effects on SaO2 and cardiac output (which are the major determinants of DO2). It is not clear whether sevoflurane or propofol yields a higher cardiac output [13,14,15,16]. In the present study, we measured DO2 in patients undergoing thoracic surgery with OLV and compared differences therein between sevoflurane- and propofol-based anaesthesia. The secondary outcome was the relationship between SaO2 and DO2
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