Review of hypoxaemia in the anaesthetized horse: predisposing factors, consequences and management

Auckburally, A. and Nyman, G. (2017) Review of hypoxaemia in the anaesthetized horse: predisposing factors, consequences and management. Veterinary Anaesthesia and Analgesia, 44(3), pp. 397-408. (doi: 10.1016/j.vaa.2016.06.001)

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Abstract

Objectives: To discuss how hypoxaemia might be harmful and why the horse is particularly predisposed to developing it. To review the strategies that are used to manage hypoxaemia in anaesthetised horses, to describe how successful these strategies are and the adverse events associated with them. Databases used: Google Scholar and PubMed using the search terms – horse; pony; exercise; anaesthesia; hypoxaemia; oxygen; mortality; morbidity; ventilation perfusion mismatch. Conclusions: Although there is no evidence that hypoxaemia is associated with increased morbidity and mortality in anaesthetised horses, most anaesthetists would agree that it is important to recognise and prevent or treat it. The favourable anatomical and physiological adaptations of the horse for exercise, adversely affect gas exchange once the animal is recumbent. Hypoxaemia is recognised more frequently than in other domestic species during general anaesthesia, although its incidence in healthy horses remains unreported. The management of hypoxaemia in anaesthetised horses is challenging and often unsuccessful. Positive pressure ventilation strategies to address alveolar atelectasis in humans have been modified for implementation in the recumbent anaesthetised horse, but are often accompanied by unpredictable and unacceptable cardiopulmonary adverse effects, and some strategies are difficult or impossible to achieve in adult horses. Furthermore, the anticipated beneficial effects of these techniques are inconsistent. Increasing the inspired fraction of oxygen during anaesthesia is often unsuccessful since much of the impairment in gas exchange is a direct result of shunt. Alternative approaches to the problem involve the manipulation of pulmonary blood away from atelectatic regions of lung to better ventilated areas. However, further work is essential, with particular focus upon survival associated with general anaesthesia in the horse, before any technique can be accepted into widespread clinical use.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Auckburally, Mr Adam
Authors: Auckburally, A., and Nyman, G.
College/School:College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
Journal Name:Veterinary Anaesthesia and Analgesia
Publisher:Elsevier
ISSN:1467-2987
ISSN (Online):1467-2995
Published Online:11 January 2017
Copyright Holders:Copyright © 2017 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia
First Published:First published in Veterinary Anaesthesia and Analgesia 44(3):397-408
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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