Comparison of non-invasive and invasive blood pressure measurements in horses during anaesthesia using the oscillometric blood pressure monitor S/5 Datex Ohmeda

The purpose of this study was to assess the performance of indirect blood pressure measurements with an oscillometric blood pressure monitor (S/5, Datex-Ohmeda) in anaesthetized horses. The study was conducted as a prospective experimental study. Seven adult horses, five geldings and two mares, were used in this study. The average age was 15 +/- 8 years (mean +/- SD) and the horses were weighing between 485 and 654 kg. Invasive and non-invasive blood pressure measurements were recorded simultaneously and a total of 263 values were analyzed. The number of measurements obtained in each horse depended on the anaesthesia time (104-225 minutes). Bland and Altman analysis for repeated measurements was used for assessment of the data. Overall the most accurate measurement was achieved with mean arterial pressure (MAP) measurement with a bias of 5 mmHg compared to a bias of 7 mmHg in the systolic arterial pressure (SAP) and of 9 mmHg in the diastolic arterial pressure (DAP). The MAP proved to be the most precise in the low arterial blood pressure group (3 mmHg) followed by the medium arterial blood pressure group (5mmHg). These results show that non-invasive blood pressure measurements with Datex Ohmeda (S/5, Datex-Ohmeda, S/5 (TM) Collect, Datex-Ohmeda) monitoring can be an adequate alternative to measure blood pressure in anaesthetized horses when invasive blood pressure measurement cannot be performed. Besides monitoring of anaesthesia, non-invasive blood pressure measurement can be very helpful in alert horses due to its non-stressful and non-invasive nature. Further comparable projects are required in awake patients and data collected in this study could serve as a basis for that.