Abstract
Objective
To compare the effect of two different intraoperative end-tidal carbon dioxide tensions
on apnoeic duration in the recovery period in horses.
Study design
Prospective randomized clinical study.
Animals
Eighteen healthy client-owned adult horses (ASA I–II) admitted for elective surgery.
Horses were of a median body mass of 595 (238–706) kg and a mean age of 9 ± 5 years.
Methods
A standardized anaesthetic protocol was used. Horses were positioned in dorsal recumbency
and randomly allocated to one of two groups. Controlled mechanical ventilation (CMV)
was adjusted to maintain the end-tidal carbon dioxide tension (Pe’CO2) at 40 ± 5 mmHg (5.3 ± 0.7 kPa) (group40) or 60 ± 5 mmHg (8.0 ± 0.7 kPa) (group60).
Arterial blood gas analysis was performed at the start of the anaesthetic period (T0),
at one point during the anaesthetic (T1), immediately prior to disconnection from
the breathing system (T2) and at the first spontaneous breath in the recovery box
(T3). The time from disconnection from the breathing system to return to spontaneous
ventilation (RSV) was recorded. Data were analysed using a two sample t-test or the Mann–Whitney U-test and significance assigned when p < 0.05.
Results
Horses in group60 resumed spontaneous breathing significantly earlier than those in
group40, [52 (14–151) and 210 (103–542) seconds, respectively] (p < 0.001). Arterial oxygen tension (PaO2), pH, base excess (BE) and plasma bicarbonate (
) were not different between the groups at RSV, however, PaO2 was significantly lower in group60 during (T1) and at the end of anaesthesia (T2).
Conclusions and clinical relevance
Aiming to maintain intra-operative Pe’CO2 at 60 ± 5 mmHg (8.0 ± 0.7 kPa) in mechanically ventilated horses resulted in more
rapid RSV compared with when Pe’CO2 was maintained at 40 ± 5 mmHg (5.3 ± 0.7 kPa).
Keywords
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Article info
Publication history
Accepted:
January 22,
2015
Received:
August 14,
2014
Identification
Copyright
© 2016 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Inc. All rights reserved.