A study of the correlation between objective and subjective indices of recovery quality after inhalation anaesthesia in equids

Objective To examine the association between objective and subjective descriptors used for assessing recovery quality in horses after anaesthesia. Study design Prospective clinical study. Animals Two hundred and seventy-six equids (110 mares, 85 entire males and 81 geldings), ASA 1-5, weighing 50-850 kg and aged 1 month - 25 years. Methods Recoveries after general anaesthesia were assisted with head and tail ropes by two anaesthetists. One scored dichotomous objective descriptors (DOD) of recovery. Two dichotomous objective scales (DOS) were then generated from those descriptors. The same individual also scored overall recovery quality using a visual analogue scale (VAS). The second anaesthetist scored recovery (good or bad) using a dichotomous subjective scale (DSS). Each DOD, the DSS and VAS were compared with each other using Pearson's chi-square test. DOSs were compared to the DSS using Wilcoxon's test and to the VAS using a Spearman's correlation test. Results Most DODs were associated (p < 0.05) with DSS and VAS. The DSS was not associated with resting/not resting in sternal recumbency (p = 0.535) nor with the time spent in sternal recumbency (p = 0.09). VAS and DSS scores were strongly associated (p < 0.0001). The two DOSs were in agreement with DSS (p < 0.0001) and negatively correlated to VAS (r(1)2 = 0.38, r(2)2 = 0.34, respectively, p-value < 0.0001). Conclusion Objective descriptors were linked closely with the subjective evaluations of recovery quality except for the presence or absence of a sternal recumbency phase and its duration. Clinical relevance These components may not be essential in recovery scoring systems. The DOS were in agreement with DSS and VAS and could be a useful tool for further studies on recoveries.