“…This dog was premedicated with acepromazine, which has alpha‐1 (α1) adrenoreceptor antagonist effects 9,16 . In a recent study in isoflurane‐anaesthetised dogs, incremental doses of acepromazine (10, 25, 50, and 100 μg/kg IV) produced a dose‐related increase in cardiac index and a decrease in systemic vascular resistance index 20 . It is possible that the hypotension observed in this case could be due to the compounded effect of both acepromazine and terbutaline administration.…”
This case report describes events that occurred under general anaesthesia of a dog undergoing transvenous pacemaker implantation for third‐degree atrioventricular block. Following premedication with acepromazine and buprenorphine, general anaesthesia was induced with alfaxalone, and maintained with isoflurane in oxygen. The dog developed severe hypotension during the procedure with concurrent bradycardia before commencement of pacing. In order to increase the heart rate, terbutaline was administered intravenously. This was followed by a worsening of the hypotension, with only a small increase in heart rate. Blood pressure improved following noradrenaline infusion. The animal recovered uneventfully in intensive care, and was sedated due to its anxious temperament to avoid dislodgement of the pacemaker device in the postoperative period.
“…This dog was premedicated with acepromazine, which has alpha‐1 (α1) adrenoreceptor antagonist effects 9,16 . In a recent study in isoflurane‐anaesthetised dogs, incremental doses of acepromazine (10, 25, 50, and 100 μg/kg IV) produced a dose‐related increase in cardiac index and a decrease in systemic vascular resistance index 20 . It is possible that the hypotension observed in this case could be due to the compounded effect of both acepromazine and terbutaline administration.…”
This case report describes events that occurred under general anaesthesia of a dog undergoing transvenous pacemaker implantation for third‐degree atrioventricular block. Following premedication with acepromazine and buprenorphine, general anaesthesia was induced with alfaxalone, and maintained with isoflurane in oxygen. The dog developed severe hypotension during the procedure with concurrent bradycardia before commencement of pacing. In order to increase the heart rate, terbutaline was administered intravenously. This was followed by a worsening of the hypotension, with only a small increase in heart rate. Blood pressure improved following noradrenaline infusion. The animal recovered uneventfully in intensive care, and was sedated due to its anxious temperament to avoid dislodgement of the pacemaker device in the postoperative period.
“…Many anaesthetic drugs have negative inotropic effects; α2‐adrenergic agonists, propofol, alfaxalone and volatile anaesthetics all reduce contractility to some extent. Recently, Rangel and others (2021) demonstrated that acepromazine may also cause a reduction in contractility. In healthy animals, this is well tolerated, but in animals at risk of developing PAH, these drugs may make the problem worse.…”
Section: Pathophysiology and Management Of Hypotension During General...mentioning
Background: Hypotension, or low arterial blood pressure (ABP), is a common complication during general anaesthesia, even in otherwise healthy animals. Recognition of the problem and an understanding of why it is occurring is necessary so that appropriate treatment can be implemented. Persistent hypotension may lead to organ injury if left untreated and can contribute to poor patient outcomes.Aim of the article: This article discusses the pathophysiology of hypotension during general anaesthesia and the treatment options available. Part one of this two‐part series, published in last month's In Practice, reviewed the physiology and measurement of ABP.
“…This suggests that administering low doses of acepromazine (5 to 10 μg/kg) is not necessarily advantageous in terms of reducing side effects, particularly considering that sedation is reduced with low doses compared to higher doses of acepromazine (Rangel and others 2020). However, it is important to be aware that hypotension can occur when acepromazine premedication is followed by anaesthesia with volatile agents, and this is associated with a reduction in systemic vascular resistance (Rangel and others 2021). …”
Section: Clinical Pharmacology Of Commonly Used Premedicant Agentsmentioning
Background: Premedication is an integral part of any anaesthetic protocol and the drugs chosen for premedication will determine the characteristics of the ensuing anaesthetic. Choosing appropriate premedicant drugs for the individual patient is vital to ensure a smooth and stress‐free anaesthetic. Normally, a balanced premedication protocol involving both a sedative and a hypnotic is advocated. This allows the two key aims of premedication – sedation and analgesia – to be met. Synergistic sedation between most sedatives and opioids also means that combining these drugs allows lower doses of each individual agent to be used.Aim of the article: This article discusses how it is important to know the clinical pharmacology of the different drugs used for premedication in order to make a rational decision about premedicant selection. One way to think about premedicant selection is based on the American Society of Anaesthesiologists (ASA) physical status classification system of the cat or dog, whereby the health status of the individual is used to inform about suitable premedication protocols.
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