VNJ Articlesanaesthesiaarterial blood pressureblood pressurehypotension
14 April 2026
Maintaining normotension in anaesthetised patients. A Literature Review
Author: Holly Rattigan, BSc(Hons), RVN
ABSTRACT Arterial blood pressure monitoring is a key component of safe general anaesthesia, yet it is not always performed as consistently as other physiological measurements. This article reviews the evidence surrounding hypotension in anaesthetised small animal patients, its causes and consequences, and the relative merits of invasive and non-invasive monitoring techniques. Blood pressure is described as the driving force for tissue perfusion, determined by cardiac output and systemic vascular resistance, and mean arterial pressure (MAP) is used as the primary indicator of perfusion adequacy. In cats and dogs, a MAP of at least 60 mmHg is required to maintain perfusion of vital organs, with values below this threshold classified as hypotensive. The review explores factors contributing to hypotension under anaesthesia, including drug induced cardiovascular depression, changes in preload, afterload and myocardial contractility, and patient-related variables such as bodyweight and subclinical dehydration. Studies assessing perioperative hypotension highlight that it is a common occurrence in dogs and cats, and that reduced perfusion may contribute to organ dysfunction, particularly affecting the kidneys. Intravenous fluid therapy is discussed as a recognised intervention to support circulating volume and improve blood pressure, with evidence demonstrating increases in MAP during isoflurane-induced hypotension. Studies comparing methods for monitoring blood pressure have identified invasive blood pressure measurement as the most accurate technique, and it also produces continuous real-time values and waveforms. However, non-invasive methods are valuable where invasive monitoring is not feasible. The article concludes that veterinary nurses should prioritise routine blood pressure monitoring so timely interventions can be used to support normotension and minimise anaesthetic risk.
Keywords anaesthesia, hypotension, arterial blood pressure, blood pressure
DOI: https://doi.org/10.56496/IKIN2344
To cite this article: Rattigan, H. (2026) Maintaining normotension in anaesthetised patients. A Literature Review. VNJ 41(2) pp34-40.
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