Agreement between the Petmap Oscillometric Device and Doppler Ultrasonic for Systolic Blood Pressure Measurement in Conscious Dogs

Background: Arterial blood pressure (BP) monitoring is essential to evaluate cardiovascular performance in clinical practice and during anesthetic procedures in veterinary patients. Measurement of blood pressure can be performed directly (invasively) or indirectly (non invasively). When using non-invasive methods such as the Doppler ultrasonic and oscillometric devices, the accuracy of these methods should be evaluated before they can be used in clinical practice. The present study aimed to determine the agreement between systolic arterial blood pressure (SAP) measured by the Doppler ultrasonic and the Petmap oscillometric device in conscious dogs. Materials, Methods & Results: Thirty one healthy dogs weighing 13.2 +/- 4.5 kg were used. The dogs were positioned in lateral recumbency and SAP measurements were performed in the non-dependent thoracic limb. All blood pressure measurements were performed using the blood pressure cuff provided by the manufacturer of the Petmap device. The cuff was positioned proximal to the carpus and its width was approximately 50% of limb circumference. Blood pressure measurements with the Doppler ultrasonic were conducted using a standard technique. A sphygmomanometer was connected to the cuff and the Doppler flow probe was positioned over the common metacarpal artery after the hair was clipped and conductive gel was applied. Three consecutive measurements of SAP were obtained with the Doppler and the mean was used for analysis. Immediately after measurements with the Doppler, the blood pressure cuff was connected to the Petmap, a single automated measurement was obtained and the SAP value was recorded. For each dog, eight pairs of SAP measurements (Doppler measurements followed by the Petmap measurement) were obtained with a minimum of 5-min intervals. Agreement between paired measurements of SAP were analyzed by the Bland Altman method (considering the Doppler as the standard and the Petmap as the alternative method) and the Pearson correlation. The differences between paired observations were classified as <= 10 mmHg, <= 20 mmHg and > 20 mmHg. A total of 248 pairs of measurements were recorded: 213 were obtained during normotension (SAP: 90-150 mmHg) and the remaining 35 were obtained during hypertension (SAP > 150 mmHg). A significant correlation was found between the methods (r = 0.78; P < 0.0001). The observed bias +/- standard deviation (SD) was -5.8 +/- 14.4 and the 95% limits of agreement were -34.0 to 22.5 mmHg. The percentages of differences between the methods = 10 mmHg, = 20 mmHg and > 20 mmHg were 60%, 87%, and 13%, respectively. Discussion: The American College of Veterinary Internal Medicine (ACVIM) guidelines requires the following standards for validation of BP measurement devices: bias +/- 10 mmHg or less with a SD of 15 mmHg or less; r = 0.9 or higher; at least 50% of paired measurements lie within a 10 mmHg difference; at least 80% of paired measurements lie within a 20 mmHg difference. With the exception of the correlation coefficient (r), all other standards required by the ACVIM were achieved in the present study. The main limitation of this study was that most measurements were obtained during normotension. Therefore, these results may not apply to dogs presenting hypotension or hypertension. Results of the present study found a good agreement between SAP values obtained by the Doppler ultrasonic and the Petmap device in normotensive conscious dogs.