Agreement of Doppler Ultrasound and Visual Sphygmomanometer Needle Oscillation with Invasive Blood Pressure in Anaesthetised Dogs

Visual sphygmomanometer needle oscillation (SNO) can occur before audible return of pulsatile flow (ARPF) when measuring blood pressure by Doppler ultrasound. The aim was to assess the agreement of SNO and ARPF with invasive blood pressure (iABP) in a clinical population of anaesthetised dogs. A total of 35 dogs undergoing surgery in dorsal recumbency necessitating arterial cannulation were included. Paired measurements of iABP and SNO, and iABP and ARPF, were collected. The agreement of non-invasive blood pressure (NIBP) and iABP measurements was analysed with concordance correlation coefficients (CCCs) and Bland-Altman plots. The proportions of SNO and ARPF measurements between 10 and 20 mmHg of iABP were compared. Both SNO and ARPF demonstrated greater agreement with invasive systolic (iSAP) than invasive mean (iMAP) pressures, and SNO demonstrated greater agreement with iSAP than ARPF measurements. The mean differences (95% limits of agreement) for SNO and APRF were -9.7 mmHg (-51.3-31.9) and -13.1 mmHg (-62.2-35.9), respectively. The CCC (95% CI) for SNO was 0.5 (0.36-0.64) and ARPF was 0.4 (0.26-0.54). A significantly greater proportion of SNO measurements were within 20 mmHg of iSAP compared to ARPF. Both NIBP techniques performed more poorly than veterinary consensus recommendations for device validation. Caution should be used clinically when interpreting values obtained by Doppler ultrasound in anaesthetised dogs.

Ultrasonic Doppler as a guide for feline peripheral arterial catheterization

OBJECTIVES

The study aimed to determine if an ultrasonic Doppler-guided technique (UDGT) leads to improved placement efficacy (time, success) of feline dorsal pedal arterial catheters vs the traditional palpation-guided technique (TPT).

METHODS

A total of 26 adult, client-owned cats requiring sedation or general anesthesia for any reason, aged >12 months and weighing >3.0 kg, and with Doppler blood pressure measurements of at least 80 mmHg were enrolled. Each hindlimb was randomly assigned for dorsal pedal arterial catheterization using either the UDGT or TPT. With the UDGT, the location of the artery was identified by an audible sound using the Doppler. Successful catheter placement was confirmed by visualization of an arterial pressure waveform using a transducer and monitor system attached to the catheter. The Kaplan-Meier method and log-rank test were used to compare the two techniques.

RESULTS

The overall proportion of successful arterial catheterization was 17% (9/52): 19% (5/26) via UDGT and 15% (4/26) via TPT. Among successful arterial catheterizations (n = 9), the mean time to catheterization was 339 ± 198 s: 328 ± 237 s (n = 5) with UDGT and 353 ± 171 s (n = 4) with TPT. The log-rank test showed the two techniques were not significantly different in likelihood of successful arterial catheter placement or time to successful catheterization (P = 0.698). An arterial flash occurred in 62% (32/52) of the limbs, 58% (15/26) with the UDGT and 65% (17/26) with the TPT. Complications (self-limiting bruising, hematoma formation) were observed equally between UDGT (3/26 limbs) and TPT (3/26 limbs) in six cats.

CONCLUSIONS AND RELEVANCE

The UDGT did not improve the efficacy of catheter placement compared with the TPT. Few complications were associated with arterial catheterization.

A clinically utilized intravenous continuous rate infusion of diltiazem does not significantly decrease systolic function in healthy dogs

OBJECTIVE

To determine if left ventricular systolic function on echocardiography, systemic blood pressure, and electrocardiography change with a clinically accepted intravenous (IV) diltiazem constant rate infusion (CRI) compared to a control.

ANIMALS

10 healthy client-owned adult dogs.

PROCEDURES

Prospective, masked, crossover study from May 27, 2021, to August 22, 2021. Dogs were randomized to receive diltiazem (loading dose of 240 μg/kg, IV followed by a CRI of 6 μg/kg/min for 300 minutes) or the same volume of 5% dextrose in water (D5W) administered IV followed by the opposite intervention after a 7-day washout. Blood pressure was monitored during each CRI, and echocardiographic and electrocardiographic studies were performed immediately before the CRI and during the last hour of the CRI.

RESULTS

Postdiltiazem systolic time interval (STI) (median, 0.30; range, 0.16 to 0.34) was significantly lower than post-D5W STI (median, 0.32; range, 0.22 to 0.40; P = .046). All other echocardiographic parameters did not differ significantly between each of the groups after receiving diltiazem or D5W. Systemic blood pressure did not change significantly with either diltiazem (P = .450) or D5W (P = .940), and none of the dogs became hypotensive at any point in the study. Expectedly, negative dromotropy was observed with diltiazem.

CLINICAL RELEVANCE

A significant decrease in left ventricular systolic function was not appreciated in healthy dogs receiving diltiazem at a clinically accepted intravenous infusion rate at this dosing regimen. Further studies are needed in dogs with cardiac disease.

Use of vasopressors for treatment of vasodilatory hypotension in dogs and cats by Diplomates of the American College of Veterinary Emergency and Critical Care

OBJECTIVE

To identify the most common practices of Diplomates of the American College of Veterinary Emergency and Critical Care (DACVECCs) as they relate to the recognition and treatment of hypotension in dogs and cats, particularly concerning the use of vasopressors in vasodilatory shock states.

DESIGN

A survey regarding vasopressor use was sent to all active DACVECCs using the Veterinary Information Network. Questions focused on respondent characteristics, method of recognition of hypotension, triggers for initiation of vasopressor therapy, first- and second-line vasopressor choice, and methods of determining response to therapy.

SUBJECTS

A total of 734 DACVECCs were invited to participate, and 203 Diplomates (27.7%) completed the survey.

RESULTS

For both dogs and cats, the most common first-line vasopressor was norepinephrine (87.9% in dogs and 83.1% in cats). The most common second-choice vasopressor was vasopressin (44.2% in dogs and 39.0% in cats). Cutoff values for initiating vasopressor therapy varied between species and modality used for blood pressure measurement. In general, most DACVECCs chose to initiate vasopressor therapy at a Doppler blood pressure <90 mm Hg or a mean arterial pressure of <60 or <65 mm Hg when using oscillometric or direct arterial blood pressure measurements in dogs and cats.

CONCLUSIONS

Most DACVECCs adhere to published human guidelines when choosing a first-line vasopressor. However, there is significant variability in blood pressure measurement technique, cutoffs for initiation of vasopressor use, and choice of second-line vasopressors.

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.

Characteristics of arterial catheter use and related complications in dogs and cats in an intensive care unit

OBJECTIVE

To identify characteristics of arterial catheter use, including indwelling times and reasons for removal, and analyze potential risk factors for complications based on patient- and catheter-related variables.

DESIGN

Prospective clinical study from July 2012 to September 2016.

SETTING

University teaching hospital.

ANIMALS

One hundred ninety-eight dogs and 29 cats with an arterial catheter monitored in the ICU.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A questionnaire was used to obtain patient and catheter information for arterial catheters monitored in the ICU during the study period. Two hundred twenty-seven catheters met the inclusion criteria. Most catheters were placed in the dorsal metatarsal artery in dogs (90.4%) and either the dorsal metatarsal artery (51.7%) or coccygeal artery (48.3%) in cats. Weights ranged from 1.5 to 64 kg in dogs and 0.77 to 8.7 kg in cats. The median indwelling time was 24 hours for dogs and 12 hours for cats. Minor complications occurred in 19.2% of catheters in dogs and 17.2% of those in cats with removal of catheter due to complications in 13 of 198 (6.6%) for dogs and 2 of 29 (6.9%) for cats. There was no association between the incidence of complications and patient weight, catheter indwelling time, species, insertion site, catheter size, or level of consciousness during placement. There was also no association between the method of catheter maintenance (intermittent flushing or continuous pressure transducer) and the failure of a catheter to aspirate or flush.

CONCLUSIONS

Arterial catheter-related complications were relatively frequent, but most complications were minor and did not justify removal of the catheter. This suggests that the use of arterial catheters in both species is relatively safe. However, further research is needed to assess complications related to longer catheter indwelling times, particularly in cats.