Comparison of directly measured arterial blood pressure at various anatomic locations in anesthetized dogs

Effect of limb and cuff positioning on measurement of arterial blood pressure with an oscillometry device (PetMAP) in anaesthetized cats

Arterial blood pressure (ABP) is often measured with oscillometry during anaesthesia. Changing the height of the measuring cuff with respect to the level of the heart is known to affect oscillometry accuracy in some species; however, this effect has not been investigated in cats. The objective of this study was to determine the effects of raising and lowering the measuring cuff from standard position (level of the heart) on ABP, measured with PetMAP, in anaesthetised cats. ABP readings were obtained from 29 cats with the cuff at standard position (baseline), and 5 cm above and below the heart. The end-tidal isoflurane concentrations were maintained constant during data acquisition. There were no differences between baseline values and those measured below the heart, while ABP measured above the heart was consistently lower than baseline for both the thoracic and pelvic limbs (P < 0.001), with absolute differences of 8.2 (2.5 - 14) mmHg and 6.5 (3.0 - 15.0) mmHg, respectively. Systolic ABP readings at the pelvic limb were consistently higher than those at the thoracic limb at standard position (112 ± 26 versus 103 ± 21 mmHg, p = 0.010), above (106 ± 22 versus 95 ± 20 mmHg, p = 0.003), and below the heart (116 ± 26 versus 107 ± 22 mmHg, p = 0.011). This study shows that raising the cuff by 5 cm above the heart, which may become necessary during procedural positioning, results in clinically significant underestimation of ABP measured with PetMAP.

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.

Evaluation of coccygeal and radial artery Doppler blood pressure measurements in sick cats with and without abnormalities in tissue perfusion

OBJECTIVE

To compare systolic blood pressure measured by Doppler (SBP) taken from the coccygeal artery versus common digital branch of the radial artery in cats with normal and poor perfusion parameters.

DESIGN

Prospective, observational study.

SETTING

University Teaching Hospital.

ANIMALS

Eighty-five cats presenting to the emergency service for which prior emergency treatment was not received and a blood pressure was indicated on triage.

INTERVENTIONS

Systolic blood pressure was measured by Doppler using the radial and coccygeal arteries. Cats were categorized as having normal or poor tissue perfusion based on physical examination.

MEASUREMENTS AND MAIN RESULTS

Agreement was poor between coccygeal and radial SBP overall with absolute and relative bias (95% limits of agreement) of 23 (-51 to 96) mm Hg and 16% (-38% to 69%), respectively. In cats with poor perfusion, the agreement was absolute bias = 28 mm Hg and relative bias = 22% and with normal perfusion absolute bias = 22 mm Hg, and relative bias = 12%. The median (interquartile range) coccygeal SBP was significantly different from the radial SBP 141 (50) mm Hg versus 120 (45) mm Hg, P < 0.001. In multivariate linear regression, heart rate was negatively associated with coccygeal SBP (r²  = 0.088, P = 0.049), and pale mucous membrane color (P = 0.034) and poor pulse quality (P = 0.007) were independently associated with lower radial SBP (r²  = 0.18).

CONCLUSIONS

Median coccygeal SBP is significantly greater than radial SBP in sick cats with both normal perfusion and hypoperfusion. Agreement between coccygeal and radial SBP is poor in cats and cannot be used interchangeably. As clinically significant differences exist between sites, the authors recommend obtaining SBP from both sites initially and choosing to monitor and trend changes with the one site that correlates most with physical examination findings.

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.

Radial vs coccygeal artery Doppler blood pressure measurement in conscious cats

Objectives The aims of the study were to compare the results of systolic blood pressure (SBP) measurements at the radial and coccygeal artery by Doppler ultrasonography and to assess the impact of gender, age, body weight, body condition score (BCS) and stress score on disagreements. Methods Eighty cats were included in this prospective, block randomised crossover trial. Blood pressure measurements were performed at home, during hospitalisation or in a local animal shelter by a single trained observer according to the latest ISFM consensus guidelines. Statistical analysis included Spearman's correlation and ANOVA. Results Measurement or site order had no effect on blood pressure measurements ( P = 0.157, P = 0.965). Correlation of radial and coccygeal SBP was moderate (rsp = 0.519, P <0.001) and measurements at the tail were by mean 18.7 ± 37 mmHg higher. The differences between the measuring sites were neither correlated with age (rsp = 0.044, P = 0.710) nor with body weight (rsp = 0.122, P = 0.337). A significant effect of BCS ( P = 0.016), but not gender ( P = 0.246) or stress score ( P = 0.424) was identified. Of the 25 cats with a coccygeal SBP ⩾170 mmHg, 14 (56%) were categorised as mildly hypertensive or normotensive when measurements were performed at the forelimb. Conclusions and relevance Choice of the measuring site, coccygeal vs radial artery, has a significant impact on Doppler ultrasonographic SBP results. In many cats, these discrepancies are huge and would certainly affect treatment decisions. Possible explanations include cone-shaped tails, especially in obese cats, leading to distal gapping or slippage of cylindrical cuffs and peripheral pulse pressure amplification. Further studies are urgently needed to clarify whether the discordances are artefacts or have a pathological background.

Agreement between invasive blood pressures measured in three peripheral arteries in anaesthetized horses under clinical conditions

OBJECTIVE

To determine agreement between invasive blood pressures measured in three peripheral arteries in anaesthetized horses undergoing elective surgery.

STUDY DESIGN

Prospective balanced incomplete block design.

ANIMALS

A total of 18 client-owned horses.

METHODS

Invasive blood pressure (IBP) was measured simultaneously in one of the following three combinations: 1) transverse facial and facial artery; 2) transverse facial and metatarsal artery; and 3) facial and metatarsal artery. The agreement in blood pressure measured for each combination was performed in six horses. At each sample time, systolic (SAP), mean (MAP) and diastolic (DAP) arterial pressures were measured concurrently in each artery, and the mean of three consecutive measurements was recorded. The position of horse, heart rate and use of dobutamine were also recorded. Bland-Altman analysis was used to assess agreement between sites.

RESULTS

A total of 54 paired measurements were obtained, with 18 paired measurements from each combination. All paired measurements showed poor and haphazard (nonsystematic) agreement. The widest limit of agreement was 51 mmHg for SAP measured in the facial artery and metatarsal artery, with a bias of -11 mmHg. The smallest limit of agreement was 16 mmHg for MAP measured in the transverse facial and metatarsal artery, with a bias of 1 mmHg.

CONCLUSIONS AND CLINICAL RELEVANCE

There was poor and haphazard agreement for SAP, MAP and DAP measured in each pair of peripheral arteries in this study. These results show that blood pressure measured in different peripheral arteries cannot be used interchangeably. This has implications for studies that use IBP as an outcome variable and studies determining agreement between noninvasive blood pressure and IBP measurements in horses under general anaesthesia.

Effects of various factors on Doppler flow ultrasonic radial and coccygeal artery systolic blood pressure measurements in privately-owned, conscious dogs

OBJECTIVE

The purpose of this study was to assess the effects of age, body condition score (BCS) and muscle condition score (MCS) on indirect radial and coccygeal Doppler systolic arterial blood pressure (SAP) measurements in dogs.

METHODS

Sixty-two privately-owned dogs were enrolled between June and July 2016. The BCS and MCS were determined by two investigators. Blood pressure was measured per published guidelines and using headphones, and the order of measurement site was randomized. Dogs were positioned in right lateral recumbency for radial measurements and sternal recumbency or standing for coccygeal measurements. Associations between SAP and other variables were assessed by correlation coefficients and analysis of covariance.

RESULTS

Radial and coccygeal SAP measurements were moderately correlated (r = 0.45, P < 0.01). Radial SAP measurements were higher than coccygeal SAP measurements (mean difference 9 mmHg, P < 0.01), but discordance occurred in both directions. No difference was observed between the first measurement taken, the average of measurements 2-6, or the average of all 6 measurements for either the radial (128, 129, and 129 mmHg; P = 0.36) or coccygeal (121, 122, and 122 mmHg; P = 0.82) site. Associations were not found between SAP measurements for either site and age, weight, BCS, MCS, anxiety score, or cuff size. Heart rate decreased significantly from the start of acclimation to the end of the first data collection series regardless of site (P < 0.01).

CONCLUSIONS AND CLINICAL RELEVANCE

Initial measurement site can be based on patient and operator preference given lack of associations with patient variables, but the same site should be used for serial SAP measurements given discordant results between sites.

Comparison of blood pressure measurements of anesthetized dogs obtained noninvasively with a cylindrical blood pressure cuff and an anatomically modified conical blood pressure cuff

OBJECTIVE

To compare blood pressure measured noninvasively with an oscillometric device that involved use of a novel conical cuff and a traditional cylindrical blood pressure cuff.

ANIMALS

17 adult hound-type dogs.

PROCEDURES

Dogs were anesthetized, and a 20-gauge, 1.5-inch catheter was inserted in the median sacral artery. The catheter was attached to a pressure transducer via fluid-filled noncompliant tubing, and direct blood pressure was recorded with a multifunction monitor. A specially fabricated conical cuff was placed on the antebrachium. Four sets of direct and indirect blood pressure measurements were simultaneously collected every 2 minutes. Four sets of measurements were then obtained by use of a cylindrical cuff.

RESULTS

The cylindrical cuff met American College of Veterinary Internal Medicine consensus guidelines for validation of indirect blood pressure measurements for mean arterial blood pressure (MAP), systolic arterial blood pressure (SAP), and diastolic arterial blood pressure (DAP). The conical cuff met the consensus guidelines for difference of paired measurements, SD, and percentages of measurements within 10 and 20 mm Hg of the value for the reference method, but it failed a correlation analysis. In addition, although bias for the conical cuff was less than that for the cylindrical cuff for SAP, MAP, and DAP measurements, the limits of agreement for the conical cuff were wider than those for the cylindrical cuff for SAP and MAP measurements.

CONCLUSIONS AND CLINICAL RELEVANCE

On the basis of results of this study, use of a conical cuff for oscillometric blood pressure measurement cannot be recommended.