Accuracy of the PetTrust, a non-invasive arterial blood pressure monitor, at three different measurement sites in comparison to direct blood pressure measurement in dogs anaesthetized for clinical procedures.
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Objective - To test the accuracy of the oscillometer “PetTrust” and its algorithm, and to determine at which of three standard test sites (forelimb, tail base, and hindlimb, respectively) this device reproduces arterial blood pressure measurements most accurately and reliably compared to the golden standard of invasive blood pressure measurement in dogs anaesthetized for clinical procedures. The non-invasive blood pressure measurement device PetTrust, is validated according to the recommendations of the American College of Veterinary Internal Medicine for the systolic, diastolic and mean arterial blood pressure measured at the three different body sites. Study design - A prospective clinical study. Animals - Thirty-three client-owned dogs, American Society of Anesthesiologists (ASA) grade 1 - 3 and anaesthetized for various surgical procedures, in which arterial blood pressure measurement was required. Methods - Direct arterial blood pressure measurements were obtained from the dorsal pedal artery, while indirect blood pressure was measured at the forelimb, tail base and hindlimb, respectively, using the PetTrust oscillometer. Various anaesthetic protocols tailored to the patients’ individual needs were used. Bland Altman plots were used for statistical analysis of the parameters obtained. Results - Systolic arterial blood pressure values were overestimated at both the forelimb and hindlimb 2 with a mean difference of 4.3 mmHg and 9.1 mmHg, respectively, whereas values at the tail were underestimated with a mean difference of -4.3 mmHg. The diastolic blood pressure values were overestimated at the forelimb and tail with a mean difference of 4.3 mmHg and 3.3 mmHg, respectively, but at the hindlimb values almost equal to those of the invasive method were found (mean difference of 0.1 mmHg). An overestimation of the mean arterial blood pressure value was found for all three body parts tested, in which the forelimb with a mean difference of 7.6 mmHg was the highest. The diastolic blood pressure measured on the tail was read correctly in 82% of all measurements and therefore had the highest accuracy compared to the other body parts used and other values measured, whereas the systolic blood pressure measured on the hindlimb with an accuracy of 51% only just corresponded to the recommendations of the American College of Veterinary Internal Medicine. The highest correlation coefficient of 0.74 was measured on the forelimb for the MAP, but still does not reach the American College of Veterinary Internal Medicine recommendations of ≥0.9. Conclusions - and clinical relevance The results suggest that arterial blood pressure measured non-invasively by the PetTrust is dependent on the anatomical location of the dog chosen for the cuff. This should be considered when developing future studies to validate non-invasive arterial blood pressure measurement devices. With the exception of the correlation coefficient, the PetTrust handheld blood pressure monitor complies to the American College of Veterinary Internal Medicine recommendations. The PetTrust monitor can therefore, and because of numerous other advantages, be recommended in veterinary practice. The best results, and therefore the highest accuracy, were achieved on the tail.