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Restoration of arterial oxygen tension in horses recovering from general anaesthesia
Author(s) -
Bardell D.,
Mosing M.,
Cripps P.J.
Publication year - 2020
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/evj.13142
Subject(s) - anesthesia , arterial oxygen tension , regional anaesthesia , general anaesthesia , medicine , oxygen tension , horse , tension (geology) , oxygen , biology , chemistry , materials science , paleontology , organic chemistry , lung , ultimate tensile strength , metallurgy
Summary Background Arterial hypoxaemia is common in anaesthetised horses, but little information exists regarding restoration of arterial oxygen tension (PaO 2 ) during recovery from anaesthesia, or if intra‐operative management factors exert any longer‐term effect. Objectives To evaluate PaO 2 in horses recovering from general anaesthesia up to 1 h after resuming standing. Study design Prospective observational clinical cohort study. Methods Systemically healthy adult horses undergoing inhalational general anaesthesia for elective surgical procedures were studied. Arterial blood samples were obtained anaerobically prior to pre‐anaesthetic medication, at end of anaesthesia, immediately following positioning in the recovery box, then at 10‐min intervals until standing. Additionally, samples were taken when horses achieved sternal recumbency, at standing (STAND) and 1 h after standing (STAND+1). Data were analysed using ANOVA and mixed‐effects linear regression, with significance set at P<0.05. Results Data from one hundred and two horses were analysed. Forty horses received controlled mandatory ventilation (CMV) throughout anaesthesia, 47 breathed spontaneously (SV) and 15 initially breathed spontaneously before CMV was imposed (S‐CMV). Overall, PaO 2 , P(A‐a)O 2 and PaCO 2 remained significantly lower than baseline at STAND+1 (P<0.01). CMV resulted in higher PaO 2 at the end of anaesthesia (P = 0.03) and during early recovery (P<0.01) than SV. Only in group S‐CMV did PaO 2 , P(A‐a)O 2 and PaCO 2 return to baseline values at STAND+1. Highest PaO 2 values associated with CMV were also associated with early recovery apnoea. Main limitations Non‐standardised anaesthetic management, temporal and quantitative variation in oxygen delivery during early recovery and lack of control group where oxygen was electively withheld during recovery .Conclusions Controlled mandatory ventilation results in better pulmonary function in horses as assessed by PaO 2 , P(A‐a)O 2 and PaCO 2 , an effect enhanced by an initial period of SV and still evident 1 h after standing. High PaO 2 values may contribute to early recovery apnoea but this does not adversely affect outcome. The Summary is available in Portuguese – see Supporting Information