Agreement of a veterinary-specific oscillometric noninvasive arterial blood pressure monitor (SunTech Vet30) with invasive arterial blood pressure in anaesthetised horses.

OBJECTIVE

To evaluate agreement between a veterinary-specific oscillometric noninvasive arterial blood pressure monitor and invasive arterial blood pressure (IBP) measurements in anaesthetised horses.

STUDY

DESIGN

Prospective clinical method-comparison study.

ANIMALS: A group of 46 horses undergoing general anaesthesia in dorsal recumbency.

METHODS

Paired invasive and oscillometric blood pressure measurements were recorded at 15-minute intervals. IBP was measured via a facial artery catheter, and systolic (SAP), diastolic (DAP), and mean arterial pressures (MAP) were recorded. Oscillometric measurements were obtained using a SunTech Vet30 monitor with the cuff positioned at the tail base or distal thoracic limb, according to clinical access, and hydrostatically corrected relative to the IBP transducer level. Agreement was assessed using repeated-measures Bland-Altman analysis, modelling paired differences as oscillometric minus invasive pressure with horse as a random intercept.

RESULTS

A total of 311 paired measurements were analysed. Bias was 3.1 mmHg for SAP, -0.4 mmHg for DAP and -4.5 mmHg for MAP. Limits of agreement were -24.6 to 30.8 mmHg for SAP, -24.5 to 23.7 mmHg for DAP and -30.9 to 21.9 mmHg for MAP. Proportional bias was present for DAP and MAP, indicating pressure-dependent differences. Using an IBP MAP of <70 mmHg as the reference definition of hypotension, an oscillometric MAP of <70 mmHg had a sensitivity of 0.774 and a specificity of 0.634. The area under the curve was 0.753 (95% confidence interval 0.632-0.857).

CONCLUSIONS

The studied oscillometric monitor showed wide limits of agreement with IBP and should not be considered interchangeable with IBP in anaesthetised horses.

CLINICAL RELEVANCE: Although it may provide adjunctive physiological information when IBP monitoring is not feasible, caution is warranted when using oscillometric values to detect hypotension or guide clinical decision making.