Rethinking equine anaesthetic risk: Development of a novel Combined Horse Anaesthetic Risk Identification and Optimisation tool (CHARIOT)

A Retrospective Study on Pre- and Intraoperative Predictors on the Recovery Quality of Horses After General Anesthesia

Equine anesthesia is related to high morbidity and mortality rates and recent studies suggested that the period of recovery remains the phase associated with the greatest risk of mortality in horses. Intraoperative hypotension, hypoxemia, and hypercapnia are recognized as potential determinants of recovery quality. This study, conducted at the Equine University Hospital of Liege, aimed to explore how these factors influence recovery outcomes and compare complications between non-emergency and emergency procedures. We analyzed data from 1057 horses, with a mean weight of 498 kg (ranging from 150 to 850 kg) and a mean age of 10.7 (ranging from 0.5 to 37 years), undergoing standardized general anesthesia for non-emergency and emergency procedures to assess which factors influence recovery quality. Recoveries were graded as 'good' or 'bad' and age, sex, breed, American Society of Anesthesiologists (ASA) physical status classification, weight, anesthesia duration, presence of hypotension, hypoxemia, and hypercapnia were compared with a logistic regression analysis. Our findings highlight the multifactorial nature of anesthetic recovery in horses, with breed, age, anesthesia and recovery duration, and emergency status emerging as significant influencing factors. Additionally, monitoring and managing hypoxemia and hypotension remain critical due to their recognized impact on recovery quality. However, despite their clinical relevance, the specific effects of these variables on anesthetic recovery in horses remain insufficiently studied, emphasizing the need for further research to refine perioperative management strategies and improve outcomes.

Inter-observer agreement in classifying anesthetic deaths in cats and dogs

Determining the cause of death in studies assessing mortality during small animal anesthesia poses challenges due to varying definitions of anesthetic death, limited information, and differences in evaluators' interpretations. This study aims to establish the interobserver agreement in classifying the cause of death in anesthetized animals. The observational, retrospective, multicenter study analyzed 432 deaths (83 cats and 349 dogs). Data were collected from a database of 55,022 anesthetized dogs and 14,962 anesthetized cats, created to investigate anesthetic-related mortality in these species. Three highly qualified veterinary anesthesiologists independently assessed whether the deaths were related to anesthesia, using their professional judgment. Data were collected from questionnaires that included the animal's signalment, reason for anesthesia, ASA status, drugs, anesthetic procedures, and comments from the submitting veterinarian. Light's Kappa and the intraclass correlation coefficient (ICC) measured interrater agreement among the three evaluators, while Cohen's Kappa assessed interrater reliability between pairs of observers (p < 0.05). Evaluators A, B, and C classified 296/432 (68.5%), 264/432 (61.1%), and 54/432 (12.5%) of the cases as anesthesia-related deaths, respectively. Agreement among the three evaluators was 128/432 (29.6%) [Light's Kappa: 0.17, p = 0.00026; ICC: 0.06, p-value = 0.0167]. The three evaluators agreed on classifying a death as anesthetic-related in 14.1% of cases (50 out of 354 cases where at least one evaluator classified the death as anesthetic-related). Similarly, for non-anesthetic-related deaths, the three evaluators reached an agreement in 20.4% of cases (78 out of 382 cases where at least one evaluator classified the death as non-anesthetic-related). Overall, agreement between two out of three evaluators was 304/432 (70.4%). Evaluators A and B had a 65.7% agreement [Cohen's Kappa: 0.25, p < 0.00001], A and C had a 46.6% agreement [Cohen's Kappa: 0.10, p < 0.00001], and B and C had a 50.9% agreement [Cohen's Kappa: 0.16, p < 0.00001]. In conclusion, the evaluators' agreement was weak, highlighting the need for a consensus on defining anesthetic mortality in dogs and cats.

Risk assessment in equine anesthesia: a first evaluation of the usability, utility and predictivity of the two-part CHARIOT

Introduction

An accurate risk score that can predict peri-anesthetic morbidity and mortality in equine patients could improve peri-operative management, outcome and client communication.

Materials and methods

Three hunded horses underwent pre-anesthetic risk assessment using the American Society of Anesthesiologists-Physical Status augmented with equine-specific diseases (ASA-PS-Equine), a multifactorial 10-part rubric risk scale (10-RS), and a combination of both, the Combined horse anesthetic risk identification and optimization tool (CHARIOT). Intra-and post-anesthetic complications, the recovery phase and mortality were recorded over a period of 7 days following general anesthesia. To compare the utility and predictive power of the 3 scores, data were analyzed using binominal logistic regression (p ≤ 0.05) and receiver operating characteristic curve analysis. In addition, inter-observer reliability, speed, safety, ease of use and face validity of the ASA-PS-Equine and the 10-RS were analyzed based on five hypothetical patients.

Results

All scores showed statistically significant associations with various intra-anesthetic complications and parameters of the recovery phase. The discriminant ability of the scores related to the occurrence of intra-anesthetic (AUC = 0.6093-0.6701) and post-anesthetic (AUC = 0.5373-0.6194) complications was only low. The highest diagnostic accuracy for all scores was observed for overall mortality (AUC = 0.7526-0.7970), with the ASA-PS-Equine differentiating most precisely (AUC = 0.7970; 95% CI 0.7199-0.8741). Inter-observer reliability was fair for the 10-RS (κ = 0.39) and moderate for the ASA-PS-Equine (κ = 0.52). Patient assignment to the CHARIOT was predominantly rated as rather easy and quick or very quick.

Limitations and conclusion

The main limitations of the study are the monocentric study design and failure to obtain the full range of points. In conclusion, all 3 scores provide useful information for predicting the mortality risk of equine patients undergoing general anesthesia, whereas intra-and postoperative complications cannot be predicted with these scores.