Validation of noninvasive blood pressure equipment: which peripheral artery is best for comparison studies in dogs?

Agreement of high-definition oscillometry at two cuff locations with invasively measured arterial blood pressures in anaesthetised cheetahs

OBJECTIVES

To evaluate the agreement between high-definition oscillometry (HDO) used on the metatarsus or tail base with invasive arterial blood pressures measured in the dorsal pedal artery in anaesthetised cheetahs.

STUDY DESIGN

Prospective clinical study.

ANIMALS

A group of 13 captive adult cheetahs.

METHODS

Cheetahs were immobilised with medetomidine (32-45 μg kg^-1) and tiletamine/zolazepam (0.93-1.39 mg kg^-1) administered intramuscularly, and anaesthesia was maintained with either isoflurane in oxygen or continuous propofol infusion. Invasive blood pressure was measured via a 20 gauge intra-arterial catheter in the dorsal pedal artery in the metatarsus and used as a reference method for pressures simultaneously estimated using HDO on the contralateral metatarsus and tail base. Bland-Altman plots (for repeated measurements) and criteria defined by the American College of Veterinary Internal Medicine (ACVIM) were used to compare agreement according to the anatomical location of the cuff, the anaesthetic maintenance agent and magnitude of the blood pressure.

RESULTS

A total of 147 paired measurements were obtained with HDO on the metatarsus and 135 on the tail. Agreement with invasive pressures was better when HDO was used on the tail (rather than on the metatarsus) with all ACVIM criteria being met. Mean bias (a positive bias meaning that HDO overestimated the invasively measured pressures) ± standard deviation of differences for systolic, diastolic and mean arterial pressures were -7.0 ± 13.9, 4.2 ±12.1 and 4.6 ±11.2 mmHg, respectively, for HDO on the tail, and -11.9 ±15.1, 2.8 ±16.5 and 2.1 ±13.2 mmHg, respectively, for HDO on the metatarsus. Agreement was better during isoflurane anaesthesia than propofol, and at lower blood pressures than at higher.

CONCLUSIONS AND CLINICAL RELEVANCE

When used on the tail base of anaesthetised cheetahs, HDO met the ACVIM validation criteria for a noninvasive device, as compared to invasively measured pressures in the dorsal pedal artery.

Ultrasonic Doppler-guided catheterization of the dorsal pedal artery in dogs and cats under general anesthesia

BACKGROUND AND OBJECTIVE

Noninvasive blood pressure measurements are less accurate than direct measurements but arterial catheterization for direct blood pressure monitoring can be challenging especially in patients with a nonpalpable pulse. The purpose of this study is to describe a novel technique of locating the dorsal pedal arterial pulse using a portable ultrasonic Doppler for arterial catheter placement.

KEY FINDINGS

Using the described technique in anesthetized dogs and cats with strong (n = 13) to weak dorsal pedal pulses (n = 6), the overall success rate of arterial puncture was 70% (19/27) with successful catheterization in 53% (10/19) of those. The overall success rate of arterial catheterization was 37% (10/27). The pulse strength did not significantly affect the success rate. Neither were patient weight, blood pressure, heart rate, and premedication significantly different between the 2 groups.

SIGNIFICANCE

This study describes a novel technique for locating the dorsal pedal artery for arterial catheterization. Having another technique of pulse detection may increase the likelihood of arterial catheter placement for direct blood pressure monitoring and aid in arterial puncture for obtaining a sample for blood gas analysis in critical patients.

Branham sign in dogs undergoing interventional patent ductus arteriosus occlusion or surgical ligation: A retrospective study

Background:

The Branham sign is a baroreceptor response that follows patent ductus arteriosus (PDA) closure. Although described in dogs following both interventional and surgical ductal closure, a direct comparison of the Branham sign elicited by these two techniques has not been made.

Aim:

Since closure with an Amplatz canine ductal occluder (ACDO) occurs over 10 minutes and surgical ligation (SL) is more rapid, we hypothesized that the Branham sign following occlusion of a PDA with an ACDO would be less severe than following SL.

Methods:

Clinical records of dogs diagnosed with left-to-right shunting PDA between 2008 and 2018 were retrospectively reviewed. Of 139 dogs undergoing PDA occlusion, only 41 dogs (ACDO n = 32, SL n = 9) were included after applying exclusion criteria. Heart rate (HR) and blood pressure (BP) from occlusion time (T₀) until 30 minutes post occlusion (T₃₀) were recorded. Signalment and anesthetic protocol were also recorded. The influence of age and weight on the hemodynamic variations was assessed. Hemodynamic variables and calculations were compared between and within groups using a repeated measures general linear model, and post hoc tests were applied if significance was identified.

Results:

A mild Branham sign was present in both groups, and hemodynamic changes were not significantly different between groups. In both groups, there was a significant decrease in HR (11 bpm, 5.3–16.3; p < 0.001) (10.4%, 5.4–15.5; p < 0.001) and increase in diastolic BP (9.5 mmHg, 3–16; p = 0.002) (23.5%, 7.1–39.9; p = 0.002), but systolic BP did not change significantly (p = 0.824). Age and weight did not influence Branham sign.

Conclusion:

The Branham sign in dogs is mild in both groups, lasts for at least 30 minutes, and is independent of the method of PDA closure.

Comparison of Simultaneous Measurements of Forelimb and Hindlimb Systolic Blood Pressure in Conscious Dogs

Blood pressure is commonly measured in veterinary medicine. Previous studies have used indirect measurements to compare the forelimb and hindlimb blood pressure in dogs, and yielded contradictory results. Notably in these studies, the measurement of both limbs was not performed simultaneously. In this study, Doppler ultrasonography was used to measure systolic arterial pressure (SAP) and pulse rate (PR) simultaneously on the median palmar artery of forelimb and the medial plantar artery of hindlimb in 108 conscious dogs. The optimal cuff size was selected using 30-40% of the limb circumference. The SAP of forelimb and hindlimb were 149.5 ± 28.5 mm Hg and 152.3 ± 31.1 mm Hg. The PR of forelimb and hindlimb were 113.9 ± 31.7 beats per minute (bpm) and 113.1 ± 31.2 bpm, respectively. The SAP and PR of the forelimb and hindlimb correlated significantly (Pearson R² = 0.696, P < .001; Pearson R² = 0.966, P < .001). There was no significant difference in SAP and PR between the forelimb and hindlimb (P = .1; P = .184). There was no significant difference in the SAP and PR of the forelimb and hindlimb using Doppler device measurement in conscious dogs. Both sites of blood pressure measurement could be adequate for analyzing trends in blood pressure.

Validation of the oscillometric blood pressure monitor Vet20 SunTech in anesthetized healthy cats

OBJECTIVE

To evaluate a veterinary-specific oscillometric noninvasive blood pressure (NIBP) system according to the guidelines of the American College of Veterinary Internal Medicine (ACVIM) Consensus Statement.

STUDY DESIGN

Prospective clinical study.

ANIMALS

A total of 33 client-owned cats (20 females and 13 males).

METHODS

Cats were premedicated with methadone (0.3 mg kg^-1) and alfaxalone (2 mg kg^-1) intramuscularly. After 15 minutes anesthesia was induced with isoflurane (3%) in 100% oxygen by facemask while breathing spontaneously. A 22 gauge catheter was placed in the median caudal artery and systolic (SAP), diastolic (DAP) and mean (MAP) arterial pressures were measured. NIBP measurements were collected by placing the cuff (40% of limb circumference) on the right or left antebrachium. The agreement between the two methods was evaluated with the Bland-Altman methods, and the oscillometric NIBP device was evaluated using the ACVIM guidelines for validation of devices.

RESULTS

Data from 30 of the 33 cats were analyzed. Five paired measurements were taken from each cat, totaling 150 paired measurements. Mean bias (limits of agreements) for SAP, DAP and MAP were 2.7 (-22.7 to 28.1), 0.9 (-22.3 to 24.2) and 1.3 (-20.4 to 23.0). The oscillometric NIBP passed all validation criteria, except correlation which was <0.9 for SAP, DAP and MAP.

CONCLUSIONS AND CLINICAL RELEVANCE

The Vet20 did not meet all validation criteria by the ACVIM. However, all criteria except correlation were met.