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Objective To determine if blood pressure measured with an ultrasonic Doppler flow detector (Doppler) is in good agreement with directly measured blood pressures in anesthetized cats. Design Prospective observational study. Setting University veterinary teaching hospital. Animals Thirty-nine cats undergoing routine neutering. Interventions Cats were divided into 2 groups; 19 cats enrolled in Group A had a 24-Ga catheter inserted into a dorsal pedal artery; 20 cats in Group B had a 20-Ga catheter placed in a femoral artery. In both groups, systolic, diastolic, and mean arterial pressures were directly measured using a validated pressure measurement system. Indirect values were compared against direct blood pressure measurements. Results There was no difference between groups. Overall, there was poor agreement with a significant bias observed between Doppler and directly measured blood pressures. For the systolic arterial pressure the bias was −8.8 with limits of agreements (LOA) of −39.3 and 21.7. For the mean arterial pressure, the bias was 14.0 with LOA of −13.9 and 41.9. For the diastolic arterial pressure, the bias was 27.9 with LOA of −4.4 and 60.2. Methodology, weight, sex, and replicates did not have a significant effect on the difference between indirect and direct measurements in any model. Conclusions Results suggest poor agreement between Doppler values and directly measured blood pressures in anesthetized cats. Use of Doppler in cats could be misleading and readings should be interpreted with caution in a clinical context.

Objective To determine if an oscillometric device optimized for use in dogs produces systolic, diastolic, and mean arterial pressures (MAPs) measurements that are in good agreement with directly obtained pressures Design Prospective study. Setting University teaching hospital. Animals Twenty-one dogs under general anesthesia for surgical procedures. Interventions A 20-Ga catheter was placed into the dorsal pedal artery and systolic, diastolic, and MAPs were directly measured using a validated blood pressure measurement system. Indirect blood pressure measurements were collected using a widely available veterinary oscillometric blood pressure unit. Results obtained by the 2 methods were then compared. Measurements and Main Results Agreement between the directly and indirectly measured pressure demonstrated a bias of 9.9 mm Hg and limits of agreement (LOA) 73.7 to −53.9, a bias of −8.9 mm Hg and LOA 23.3 to −41.2, and a bias of −6.3 mm Hg and LOA 28.2 to −40.8 for systolic, diastolic, and MAP, respectively. Conclusions There was poor agreement between the direct and indirect measured blood pressure measurement systems. Therefore, use of the oscillometric blood pressure unit evaluated in this study for monitoring patients under anesthesia cannot be recommended at this time.

Objective – To determine the accuracy and precision of an oscillometric noninvasive blood pressure device as a predictor of invasive direct blood pressure in healthy anesthetized hypotensive and normotensive dogs. Design – Prospective observational study. Setting – University teaching hospital. Animals – Eight crossbred adult dogs. Interventions – Anesthesia was induced with propofol and maintained with isoflurane. A catheter was placed in the dorsal pedal artery to record systolic, mean, and diastolic arterial blood pressures (aSAP, aMAP, and aDAP, respectively). The noninvasive blood pressure device cuff was placed around the contralateral front limb to record noninvasive systolic, mean, and diastolic blood pressure (nSAP, nMAP, and nDAP). Two states of blood pressure (BP) were studied: baseline state was established by keeping end-tidal isoflurane concentration at 1.2±0.1%. The hypotensive state was achieved by maintaining the same isoflurane concentration while withdrawing approximately 40% of the animal's blood volume until aMAP was stable at approximately 40 mm Hg. At the end of the study, blood was returned to the animal and it was allowed to recover from anesthesia. Measurements and Main Results – Agreement between the direct and indirect BP measurements was determined by the Bland-Altman method. The SAP and MAP but not DAP bias varied significantly between each BP state. Normotensive absolute biases (mean [SD]) for SAP, MAP, and DAP were −14.7 mm Hg (15.5 mm Hg), −16.4 mm Hg (12.1 mm Hg), and −14.1 mm Hg (15.8 mm Hg), respectively. Absolute biases during the hypotensive state for SAP, MAP, and DAP were −32 mm Hg (22.6 mm Hg), −24.2 mm Hg (19.5 mm Hg), and −16.8 mm Hg (17.2 mm Hg), respectively. Conclusion – The oscillometric device was not reliably predictive of intra-arterial BP during hypotension associated with acute hemorrhage.