Förebyggande djuromvårdnad mot post-anestetisk myopati hos häst
Post-anaesthetic myopathy (PAM) is a serious occasional complication of general anaesthesia in horses. It causes not only pain and suffering to the horse, but also suffering (trauma) to the owner with increased veterinary costs. In the worst case PAM can be fatal. The anaesthetic nurse must know which parameters have to be taken into consideration in the prevention of PAM, to be able to prevent it, and use that knowledge for the animals safety. The aim of this literature review was to investigate and make a presentation of the factors and measurements associated with PAM, with focus on how to monitor these measurements to prevent it from happening, and the advice a Veterinary nurse can give to the horse owner regarding this condition.
According to literature there a few factors that greatly increase the risk of PAM, these include- hypotension, periods less than 60 mmHg significantly increases the risk. Duration of the anaesthesia, over 90 min also significantly increases the risk, and pressure on the skeletal muscles. Physiological measurements associated with these factors: mean arterial blood pressure (MAP), cardiac output (CO), intra compartmental pressure, perfusion pressure, muscle perfusion, muscle metabolism, lactate, end-tidal carbon dioxide, stroke volume (SV), system vascular resistance (SVR) and heart rate. Different monitoring devices and techniques comprises: (direct) blood pressure, electrocardiography, capnography manual palpation of peripheral pulse rate and quality, pulse oximetry, mucous membrane colour, capillary refill time (CRT) and some less common methods (laser doppler flowmetry and microdialyse), not yet developed for clinical use. Prophylactic measures: maintaining adequate blood pressure that is more than 70 mmHg, reducing the length of the anaesthesia and the use of protective padding and proper positioning. Regarding advice for horse owners it?s best to give a cautious prognosis, and show great empathy in all consultations. Horse owner's role in preventing post-anaesthetic myopathy still needs to be clarified as well as what advice the veterinary nurse can give. Focus is to inform horse owners about the risks. In the current situation, good animal care during anaesthesia is paramount.