Changes in oxygen supply-demand balance during induction of general anesthesia: an exploratory study using remimazolam

J Anesth. 2024 Oct;38(5):622-630. doi: 10.1007/s00540-024-03362-0. Epub 2024 Jun 6.

Abstract

Purpose: This study was performed to evaluate the changes in oxygen supply-demand balance during induction of general anesthesia using an indirect calorimeter capable of measuring oxygen consumption (VO2) and carbon dioxide production (VCO2).

Methods: This study included patients scheduled for surgery in whom remimazolam was administered as a general anesthetic. VO2 and VCO2 were measured at different intervals: upon awakening (T1), 15 min after tracheal intubation (T2), and 1 h after T2 (T3). Oxygen delivery (DO2) was calculated simultaneously with these measurements. VO2 was ascertained using an indirect calorimeter and further calculated using vital signs, among other factors. DO2 was derived from cardiac output and arterial blood gas analysis performed with an arterial pressure-based cardiac output measurement system.

Results: VO2, VCO2, and DO2 decreased significantly from T1 to T2 and T3 [VO2/body surface area (BSA) (ml/min/m2): T1, 130 (122-146); T2, 107 (83-139); T3, 97 (93-121); p = 0.011], [VCO2/BSA (ml/min/m2): T1, 115 (105-129); T2, 90 (71-107); T3, 81 (69-101); p = 0.011], [DO2/BSA (ml/min/m2): T1, 467 (395-582); T2, 347 (286-392); T3, 382 (238-414); p = 0.0020]. Among the study subjects, a subset exhibited minimal reduction in VCO2. Although the respiratory frequency was titrated on the basis of end-tidal CO2 levels, there was no significant difference between the groups.

Conclusion: General anesthetic induction with remimazolam decreased VO2, VCO2, and DO2.

Keywords: General anesthesia; Oxygen consumption; Oxygen supply; Oxygen supply–demand balance; Remimazolam.

MeSH terms

  • Adult
  • Aged
  • Anesthesia, General* / methods
  • Benzodiazepines* / administration & dosage
  • Blood Gas Analysis / methods
  • Carbon Dioxide* / metabolism
  • Cardiac Output / drug effects
  • Cardiac Output / physiology
  • Female
  • Humans
  • Hypnotics and Sedatives / administration & dosage
  • Hypnotics and Sedatives / pharmacology
  • Male
  • Middle Aged
  • Oxygen Consumption* / drug effects
  • Oxygen Consumption* / physiology
  • Oxygen* / blood
  • Oxygen* / metabolism

Substances

  • remimazolam
  • Oxygen
  • Carbon Dioxide
  • Benzodiazepines
  • Hypnotics and Sedatives