Doppler ultrasound is more accurate than pulse oximeter plethysmography in the measurement of systolic arterial pressure from the median caudal artery in anesthetized dogs

OBJECTIVE To compare the accuracy of doppler ultrasound (DOP) and pulse oximeter plethysmography (POP) in the measurement of systolic arterial pressure (SAP) to invasive blood pressure (IBP) in anesthetized dogs. ANIMALS 40 client-owned healthy dogs > 10 kg. METHODS Dogs were anesthetized for surgical procedures in dorsal recumbency. Invasive blood pressure was measured from a dorsal pedal artery. DOP and POP device probes were placed over the median caudal artery with a flow-occluding cuff for noninvasive blood pressure measurement. Systolic arterial pressure measured by DOP, loss of pulse oximeter plethysmograph (POP L ), and return of pulse oximeter plethysmograph (POP R ) were compared to SAP measured by IBP. A linear mixed model was used to determine correlation. Bland-Altman analyses were performed to determine bias, SD, and limits of agreement. The accuracy of DOP and POP was compared to IBP across different tensive states. RESULTS Conditional R 2 values for DOP, POP L , and POP R versus IBP were 0.92, 0.85, and 0.87, respectively (all P < .001). The biases for DOP, POP L , and POP R compared to IBP were +7.6 ± 13.1, +3.9 ± 14.4, and +8.6 ± 15.2 mm Hg (bias ± SD), respectively. Limits of agreement (lower, upper) were (−18.1, +33.3), (−24.3, +32.1), and (−21.2, +38.4) mm Hg for DOP, POP L , and POP R , respectively. DOP and POP overestimated SAP during hypotension (SAP < 90 mm Hg), DOP to a lesser magnitude. CLINICAL RELEVANCE DOP measured from the median caudal artery may be acceptable for SAP measurement in dorsally recumbent, healthy anesthetized dogs > 10 kg. POP was determined an unacceptable method.