Falsely low arterial blood pressure due to pressure transducer damage in three horses

Three horses undergoing general anaesthesia for orthopaedic procedures between August 2018 and January 2019 at Langford Veterinary Equine Services, Bristol University had falsely low arterial blood pressures due to damage of the non-disposable invasive arterial blood pressure transducer interface. The invasive arterial blood pressure transducer interface is not currently a component that is checked during the anaesthetic machine check prior starting a general anaesthetic procedure. Starting treatment for hypotension based on incorrect information due to faulty equipment can have severe negative consequences for the patient, such as extreme hypertension, increased myocardial workload and oxygen demand, and reduced perfusion of splanchnic and muscle tissue due to vasoconstriction. Therefore, we recommend routinely using the square wave test and checking the integrity of the blood pressure transducer interface before starting a general anaesthetic procedure, and when unexpected hypotensive readings are obtained and/or a state of hypotension is not responsive to treatment.