Incidence of Severe Hypoxemia in Anesthetized Horses Undergoing Emergency Exploratory Laparotomy

Abstract

Prevalence and risk factors of severe hypoxemia in anesthetized horses undergoing emergency exploratory laparotomy are sparsely documented. The aim of this study was to report incidence of severe hypoxemia ( PaO₂ < 60 mmHg) in horses undergoing emergency exploratory laparotomy and identify potential risk factors for this complication. A single center retrospective cross sectional designed was used. Clinical data of 714 horses undergoing general anesthesia for emergency explorative laparotomy were reviewed. A backward stepwise elimination procedure was used to determine the final multivariable logistic regression model; all covariables with univariable P-values <.25 were incorporated, with retention of covariables with Wald P-values <.05 at each step, in order to determine which explanatory variables would be included in the final model. The overall incidence of severe hypoxemia in our population was 15.3%. Multivariable logistic regression analysis showed that increasing body weight (odds ratio [OR] 1.01, 95% confidence interval [CI] 1.0-1.01, P = .002), colon torsion (OR 3.0, 95% CI 1.3-6.8, P = .006), increased dead space ventilation (OR 1.06, 95% CI 1.04-1.09, P ≤ .001), shorter time between induction of anesthesia and collection of arterial blood gas samples (OR 0.98, 95% CI 0.98-0.99, P ≤ .001) and intratracheal aerosolized salbutamol (OR 13.5, 95% CI 7.6-24, P ≤ .001) were associated with the outcome. The incidence of hypoxemia found in our study was in line with previous literature. Increasing body weight, colon torsion and shorter time between the time of induction of anesthesia and collection of arterial blood gas samples represented risk factors for hypoxemia.

Keywords: Anesthetised horses; Colon torsion; Dead space ventilation; Increasing body weight; Severe hypoxemia.