Multi-centre clinical audit of oxygen and inhalant anaesthetic usage in equine anaesthesia: The potential benefits of training and low-flow techniques.

Research Overview

• This study audited oxygen and isoflurane use during equine anaesthesia across multiple hospitals to evaluate their greenhouse gas (GHG) emissions and assess whether targeted anaesthesia training on low-flow techniques could reduce these emissions.

Background and Importance

• The healthcare sector significantly contributes to global greenhouse gas emissions, with anaesthetic gases being important contributors.
• Equine anaesthesia typically involves the use of oxygen and inhalant anaesthetic agents like isoflurane, both of which contribute to GHG emissions.
• Low-flow anaesthesia techniques, which utilize reduced fresh gas flow rates, are promising sustainable practices that can minimize environmental impact without compromising patient care.

Research Objective

• To conduct a multi-centre audit at five equine hospitals to quantify oxygen and isoflurane usage and the associated GHG emissions.
• To evaluate the impact of implementing an anaesthesia training program focused on low-flow techniques in reducing these emissions between two audit periods.

Methods

• Audit Periods:
  • Study Period One: June 1 – September 30, 2022
  • Study Period Two: June 1 – September 30, 2023
• Data Collection:
  • Retrospective collection of patient data, anaesthesia protocols, fresh gas flow (FGF) rates, and vaporiser settings every 5 minutes during procedures.
  • Calculation of GHG emissions expressed in carbon dioxide equivalents (tCO2e).
  • Cost analysis in British Pounds (£) related to gas use.
• Intervention:
  • Between the two periods, an anaesthesia training program was implemented to promote low-flow anaesthesia techniques among clinicians.
• Statistical Analysis:
  • Applied a linear mixed-effects model to identify predictors of GHG emissions per case.
  • Significance level set at p-value < 0.05.

Key Results

• Sample Size: 414 general anaesthetic cases audited across five equine hospitals.
• Reduction in Resource Usage:
  • Isoflurane usage decreased by 9.6% between the two audit periods.
  • Oxygen usage decreased by 17.9% in the same time frame.
• Environmental Impact:
  • Overall associated GHG emissions dropped by 9.6%, from 14.6 to 13.2 tonnes of CO2 equivalents.
  • The model identified five significant predictors of GHG emissions per case:
    • Study period (reflecting the impact of training)
    • Oxygen consumption
    • Anaesthesia duration
    • Average isoflurane vaporiser setting
    • Interaction between oxygen usage and study period
  • Cases in Study Period Two had on average 10.4 kg less CO2e emissions per case (p = 0.01), showing the benefit of training.
  • Each additional litre of oxygen increased emissions by 0.12 kg CO2e (p < 0.001), underscoring oxygen usage as a major emission driver.

Conclusions and Implications

• Low-flow anaesthesia techniques introduced through targeted training demonstrated a measurable reduction in GHG emissions related to equine anaesthesia.
• Even modest reductions in oxygen and isoflurane usage can lead to meaningful environmental benefits.
• The audit’s limitations included missing data on fresh gas flows or vaporiser settings in some cases and minimal variability between hospitals, which may affect generalizability.
• Wider dissemination and adoption of low-flow anaesthesia in veterinary practice could promote sustainability in animal healthcare.
• Further research and greater professional collaboration are needed to optimize sustainable practices and confirm long-term benefits.