Effects of Cuff Size and Position on the Agreement Between Arterial Blood Pressure Measured by Doppler Ultrasound and Through a Dorsal Pedal Artery Catheter in Anesthetized Cats.

Objective To compare the effects of cuff size/position on the agreement between arterial blood pressure measured by Doppler ultrasound (ABP(Doppler)) and dorsal pedal artery catheter measurements of systolic (SAP(invasive)) and mean arterial pressure (MAP(invasive)) in anesthetized cats. Study design Prospective study. Animals A total of eight cats (3.0-3.8 kg) for neutering. Methods During isoflurane anesthesia, before surgery, changes in end-tidal isoflurane concentrations and/or administration of dopamine were performed to achieve SAP(invasive) within 60-150 mmHg. Cuff sizes 1, 2 and 3 (bladder width: 20, 25 and 35 mm, respectively) were placed on distal third of the antebrachium, above the tarsus and below the tarsus for ABP(Doppler) measurements. Agreement between ABP(Doppler) and SAP(invasive) or between ABP(Doppler) and MAP(invasive) was compared with reference standards for noninvasive blood pressure devices used in humans and small animals. Results Mean bias and precision (+/- standard deviation) between ABP(Doppler) and SAP(invasive) met veterinary standards (<= 10 +/- 15 mmHg), but not human standards (<= 5 +/- 8 mmHg), with cuffs 1 and 2 placed on the thoracic limb (7.4 +/- 13.9 and -5.8 +/- 9.5 mmHg, respectively), and with cuff 2 placed proximal to the tarsus (7.2 +/- 12.4 mmHg). Cuff width-to-limb circumference ratios resulting in acceptable agreement between ABP(Doppler) and SAP(invasive) were 0.31 +/- 0.04 (cuff 1) and 0.42 +/- 0.05 (cuff 2) on the thoracic limb, and 0.43 +/- 0.05 (cuff 2) above the tarsus. ABP(Doppler) showed no acceptable agreement with MAP(invasive) by any reference standard. Conclusions and clinical relevance The agreement between ABP(Doppler) and SAP(invasive) can be optimized by placing the occlusive cuff on the distal third of the antebrachium and above the tarsus. In these locations, cuff width should approach 40% of limb circumference to provide clinically acceptable estimations of SAP(invasive). Doppler ultrasound cannot be used to estimate MAP(invasive) in cats.