Evaluation of the agreement between lingual and thoracic limb noninvasive blood pressure with invasive blood pressure measurements in anaesthetized horses.

Objective: To evaluate the agreement between noninvasive arterial blood pressure (NIBP) measured from the tongue and thoracic limb with invasive blood pressure (IBP), and to compare NIBP measured from the tongue and thoracic limb in anaesthetized horses.

Study Design: Prospective clinical study.

Animals: A group of eight client-owned healthy horses anaesthetized for scheduled procedures, American Society of Anesthesiologists classification I-II, weighing (mean ± standard deviation) 498 ± 91 kg and aged 7.8 ± 6.75 years.

Methods: Animals were premedicated with intravenous (IV) romifidine (0.04-0.08 mg kg) and methadone (0.1 mg kg). General anaesthesia was induced IV with ketamine (2.5 mg kg) and midazolam (0.05 mg kg) and maintained with isoflurane. The facial artery was catheterized for IBP measurements. Systolic (SAP), mean (MAP) and diastolic (DAP) arterial pressures were recorded from the NIBP, NIBP and IBP every 20 minutes during the procedure. Agreement between NIBP and IBP was evaluated based on the American College of Veterinary Internal Medicine criteria and American Association for Medical Instrumentation criteria using the Bland-Altman method.

Results: The mean bias and precision between IBP and NIBP measured from the tongue met the standards for all pressure ranges (< 10 mmHg and < 15 mmHg, respectively). NIBP measurements from the tongue and thoracic limb tended to underestimate IBP measurements. During hypotension, MAP and DAP overestimated IBP, but both precision and accuracy met the criteria. The overall accuracy and precision of NIBP was poorer than NIBP. The percentage of NIBP that differed from IBP by < 10 mmHg was higher than that recorded with NIBP for SAP (46% versus 25%), MAP (77% versus 28%) and DAP (79% versus 19%).

Conclusions And Clinical Relevance: The tongue is a clinically suitable alternative for assessing arterial blood pressure compared with the thoracic limb and can reliably detect hypotension in healthy anaesthetized horses.