Associations of systemic oxygen consumption with age and body temperature under general anesthesia: retrospective cohort study

Abstract

Background: Body temperature (BT) is thought to have associations with oxygen consumption (VO₂). However, there have been few studies in which the association between systemic VO₂ and BT in humans was investigated in a wide range of BTs. The aims of this study were 1) to determine the association between VO₂ and age and 2) to determine the association between VO₂ and BT.

Methods: This study was a retrospective study of patients who underwent surgery under general anesthesia at a tertiary teaching hospital. VO₂ was measured by the Dräger Perseus A500 anesthesia workstation (Dräger Medical, Lubeck, Germany). The associations of VO₂ with age and BT were examined using spline regression and multivariable regression analysis with a random effect.

Results: A total of 7,567 cases were included in this study. A linear spline with one knot shows that VO₂ was reduced by 2.1 ml/kg/min with one year of age (p < 0.001) among patients less than 18 years of age and that there was no significant change in VO₂ among patients 18 years of age or older (estimate: 0.014 ml/kg/min, p = 0.08). VO₂ in all bands of BT < 36.0 °C was not significantly different from VO₂ in BT > = 36 °C and < 36.5 °C. Multivariable linear regression analysis showed that compared with VO₂ in BT > = 36 °C and < 36.5 °C as a reference, VO₂ levels were significantly higher by 0.57 ml/kg/min in BT > = 36.5 °C and < 37 °C (p < 0.001), by 1.8 ml/kg/min in BT > = 37 °C and < 37.5 °C (p < 0.001), by 3.6 ml/kg/min in BT > = 37.5 °C and < 38 °C (p < 0.001), by 4.9 ml/kg/min in BT > = 38 °C and < 38.5 °C (p < 0.001), and by 5.7 ml/kg/min in BT > = 38.5 °C (p < 0.001). The associations between VO₂ and BT were significantly different among categorized age groups (p = 0.03).

Conclusions: VO₂ increases in parallel with increase in body temperature in a hyperthermic state but remains constant in a hypothermic state. Neonates and infants, who have high VO₂, may have a large systemic organ response in VO₂ to change in BT.

Keywords: Body Temperature; General Anesthesia; Oxygen Consumption.

Fig. 1

Flow chart

Fig. 2

Association between oxygen consumption and age with body temperature between 36 °C and 36.5 °C. Cubic spline (left) and linear spline with one knot at the age of 18 years (right) were drawn on the scatter plot of VO₂ and age. Abbreviations: VO₂, oxygen consumption

Fig. 3

Association between oxygen consumption and body temperature. Abbreviations: VO₂, oxygen consumption; Ref, reference; *, p < 0.05; **, p < 0.01; *** p < 0.001