Evaluation of coccygeal and radial artery Doppler blood pressure measurements in sick cats with and without abnormalities in tissue perfusion.

Objective: To compare systolic blood pressure measured by Doppler (SBP) taken from the coccygeal artery versus common digital branch of the radial artery in cats with normal and poor perfusion parameters.

Design: Prospective, observational study.

Setting: University Teaching Hospital.

Animals: Eighty-five cats presenting to the emergency service for which prior emergency treatment was not received and a blood pressure was indicated on triage.

Interventions: Systolic blood pressure was measured by Doppler using the radial and coccygeal arteries. Cats were categorized as having normal or poor tissue perfusion based on physical examination.

Measurements And Main Results: Agreement was poor between coccygeal and radial SBP overall with absolute and relative bias (95% limits of agreement) of 23 (-51 to 96) mm Hg and 16% (-38% to 69%), respectively. In cats with poor perfusion, the agreement was absolute bias = 28 mm Hg and relative bias = 22% and with normal perfusion absolute bias = 22 mm Hg, and relative bias = 12%. The median (interquartile range) coccygeal SBP was significantly different from the radial SBP 141 (50) mm Hg versus 120 (45) mm Hg, P < 0.001. In multivariate linear regression, heart rate was negatively associated with coccygeal SBP (r  = 0.088, P = 0.049), and pale mucous membrane color (P = 0.034) and poor pulse quality (P = 0.007) were independently associated with lower radial SBP (r  = 0.18).

Conclusions: Median coccygeal SBP is significantly greater than radial SBP in sick cats with both normal perfusion and hypoperfusion. Agreement between coccygeal and radial SBP is poor in cats and cannot be used interchangeably. As clinically significant differences exist between sites, the authors recommend obtaining SBP from both sites initially and choosing to monitor and trend changes with the one site that correlates most with physical examination findings.