The ASA Physical Status Classification: What Is the Evidence for Recommending Its Use in Veterinary Anesthesia?-A Systematic Review.

Karine Portier,Keila Kazue Ida

doi:10.3389/fvets.2018.00204

Abstract

Background: The effectiveness of the American Society of Anesthesiologists (ASA) Physical Status (PS) classification to identify the animals at a greater risk of anesthesia-related death and complications is controversial. In this systematic review, we aimed to analyze studies associating the ASA PS scores with the outcome of anesthesia and to verify whether there was any evidence for recommending the use of the ASA PS in veterinary patients.Methods: Research articles found through a systematic literature search were assessed for eligibility, and data were extracted and analyzed using random-effects analysis.Results: A total of 15 observational prospective and retrospective studies including 258,298 dogs, cats, rabbits, and pigs were included. The analysis found consistency between the studies showing that dogs, cats and rabbits with an ASA-PS ≥III had 3.26 times (95% CI = 3.04–3.49), 4.83 times (95% CI = 3.10–7.53), and 11.31 times (95% CI = 2.70–47.39), respectively, the risk of anesthesia-related death within 24 h (dogs) and 72 h (cats and rabbits) after anesthesia compared with those with an ASA PS <III. In addition, the analysis showed that dogs and cats with ASA PS ≥III had 2.34 times the risk of developing severe hypothermia during anesthesia (95% CI = 1.82–3.01).Conclusions: The simple and practical ASA PS was shown to be a valuable prognostic tool and can be recommended to identify an increased risk of anesthetic mortality until 24–72 h after anesthesia, and a greater risk of development severe intraoperative hypothermia.

Highlights

The American Society of Anesthesiologists (ASA) physical status (PS) consists of a classification system to assess a patient’s physical status
162 were excluded because, based on the abstract, they were not relevant to our study, 25 studies were excluded because of the inclusion of patients with only a specific ASA PS, 18 were excluded because of no full data provision to calculate the relative risk (RR) and incidence of mortality or complication, and 14 studies were excluded because of no assessment of the anestheticrelated mortality and complication according to the ASA PS (Figure 5)
Mortality was assessed according to the animal species (7 studies in dogs, 6 studies in cats, 2 studies in rabbits), and according to specific populations

Summary

Introduction

The American Society of Anesthesiologists (ASA) physical status (PS) consists of a classification system to assess a patient’s physical status. Its creation dates from 1941, when Saklad et al were requested by the ASA to build a system that would allow retrieving statistical data in anesthesia (1) Their first task was ASA PS in Veterinary Anesthesia to specify arbitrary definitions of numerous variables in order to establish standard terms and a common language. They intended to develop a tool to objectively assign an operative risk and establish a prognostic. In such approach, the statistical treatment was impossible due to the numerous variables associated with the different establishments and clinicians They concluded that the term “operative risk” could not be used and it was more adequate to classify the patients according to their physical status only. We aimed to analyze studies associating the ASA PS scores with the outcome of anesthesia and to verify whether there was any evidence for recommending the use of the ASA PS in veterinary patients

Objectives

Methods

Results

Conclusion