Home blood pressure monitoring in an anaesthetic pre-admission clinic

Abstract

We suspected that many high blood pressure measurements taken in our anaesthetic pre-assessment clinic and immediately prior to induction of anaesthesia were unusually elevated due to a 'white coat' effect. These high blood pressure measurements were causing late cancellations of surgery, even though white coat measurements may not be representative of the patient's usual blood pressure or of their risk of end-organ damage due to hypertension. In this audit, patients with high blood pressure in our pre-admission clinic were provided with training and a home blood pressure monitor to use prior to surgery. These were compared to the pre-admission clinic measurements to determine the incidence of white coat hypertension. We also compared home to general practice blood pressure monitoring where possible. Fifty-two patients were provided with monitors. Fifty-one of these took at least five measurements at home. Thirty-four (66%) patients had average measurements at home at least 20 mmHg lower than pre-admission clinic measurements. A total of 33% of general practice clinic measurements were also ≥ 20 mmHg higher than average home measurements. White coat hypertension was common in our audit population. Relying on average home blood pressure measurements rather than 'one off' in-hospital measurements may have helped to prevent the postponement or cancellation of surgery for 13 patients who had recorded blood pressure ≥ 180/110 mmHg in our pre-admission clinic.