Recovery of horses from general anaesthesia: A systematic review (2000‐2020) of risk factors and influence of interventions during the recovery period

Abstract

Background In equine anaesthesia, the recovery period is a time of considerable risk and has been the focus of prolific research. Risk factors, including age, type and duration of procedure or temperament may influence recovery quality. Unfortunately, the anaesthetist is unable to control for these factors, therefore various pharmacological interventions and recovery methods have been developed with the objective of improving recovery quality. However, no consensus among anaesthetists has been reached for many of these interventions and their implications for recovery‐related mortality and morbidity. Objectives To conduct a systematic review of the published evidence relating to risk factors and interventions in the recovery period which may influence recovery quality from equine general anaesthesia (GA). Study design A systematic evaluation of the equine veterinary literature using the GRADE framework. Methods A literature search was performed and studies were assessed for eligibility by both authors utilising PRISMA guidelines. Studies meeting inclusion criteria were evaluated by both authors, categorically summarised and the quality of evidence for each sub‐topic was assessed using the GRADE framework. Results Thirty‐nine studies were identified which directly assessed the impact of risk factors and recovery interventions on recovery quality after equine GA. There was evidence to support that peri‐anaesthetic risk factors such as anaesthesia duration, American Society of Anesthesiologists (ASA) physical status and surgical procedure influenced recovery quality. We also identified sufficient evidence that administration of α‐2 adrenoreceptor agonists immediately prior to recovery, improves recovery quality. Main limitations The validity of the results of some studies may have been compromised by missing data and small sample sizes. Conclusions Recovery quality is influenced by factors including: anaesthesia duration, ASA physical status and surgical procedure. Recovery quality can be improved by the administration of an α‐2 adrenoreceptor agonist immediately prior to recovery.

Study design synopsis: Evidence syntheses—What are they and why do we need them?

“…They usually have more than one researcher duplicating methodology to increase the reliability and validity of findings. The most commonly used framework for systematic reviews is PRISMA 7,9,10 . PRISMA provides several resources, including a checklist and a template flow diagram for reporting results to structure the systematic review.…”

“…They aim to collate and analyse all the current evidence on a specific area. 7,8 The stages involved include formulating a review question, defining search criteria, defining inclusion and exclusion criteria, developing and registering a protocol, conducting a systematic search of databases, reviewing and identifying studies for inclusion, documenting reasons for exclusion, assessing quality of studies, extracting data, analysing and synthesising data and drawing conclusions. They usually have more than one researcher duplicating methodology to increase the reliability and validity of findings.…”

“…The most commonly used framework for systematic reviews is PRISMA. 7,9,10 PRISMA provides several resources, including a checklist and a template flow diagram for reporting results to structure the systematic • Initial question can be broader • Captures a wider range of evidence • Provides a mini library/ summary of publications in that area…”

“…Once selected studies are identified, quality of evidence can be assessed using a range of methodologies, including GRADE, JBI and QUADAS. 7,8,10 These provide a structured framework to evaluate the study design, population, methodology and analysis of each included publication. The findings from all included studies are then combined, for example, through meta-analysis, to generate more robust evidence from the overall data sets across different populations.…”

“…All have their place in evidence-based clinical practice and bring different advantages and disadvantages (Table 1). As increasing numbers of evidence syntheses are published, these will increase our understanding of the current bodies of evidence in veterinary medicine, 7,8 inform how we use evidence in our practices and policies 12,13 and shape how we develop future research to generate the best evidence going forwards. 15,16 Equine Veterinary Journal is publishing increasing numbers of papers describing evidence synthesis.…”