Dataset Information

Brachial artery reactivity and vascular reactive hyperemia for preoperative anaesthesia risk assessment - an observational study.

ABSTRACT:

Background

Non-invasive measures of vascular reactivity have emerged to refine cardiovascular risk. However, limited data exists investigating vascular reactivity as a preoperative diagnostic tool for anesthesiologists. In this study, we compare the utility of two non-invasive techniques, Brachial Artery Reactivity Testing (BART) and Digital Thermal Monitoring (DTM), as surrogates for measuring vascular reactivity.

Methods

Following IRB approval, 26 patients scheduled for major thoracic surgery (e.g. esophagectomy and pneumonectomy) were studied prospectively. BART [Flow mediated dilation (FMD) and Peak flow velocity (PFV)] and DTM [Temperature rebound (TR%)] were performed preoperatively at baseline using 5 minute blood pressure cuff occlusion of the upper arm. Statistical summaries were provided for the comparison of BART and DTM with select patient characteristics, and correlations were used to investigate the strength of the relationship between BART and DTM measurements.

Results

Patients preoperatively diagnosed with hyperlipidemia were associated with lower FMD% values {Median (Range): 14.8 (2.3, 38.1) vs. 6.2 (0.0, 14.3); p?=?0.006}. There were no significant associations between BART and DTM techniques in relation to cardiovascular risk factors or postoperative complications.

Conclusion

Our study suggests that impaired vascular reactivity as measured by BART is associated with the incidence of hyperlipidemia. Also, using a novel technique such as DTM may provide a simpler and more accessible point of care testing for vascular reactivity in a perioperative setting. Both non-invasive techniques assessing vascular function warrant further refinement to better assist preoperative optimization strategies aimed at improving perioperative vascular function.

SUBMITTER: Schier R

PROVIDER: S-EPMC4071153 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Publications

Brachial artery reactivity and vascular reactive hyperemia for preoperative anaesthesia risk assessment - an observational study.

Schier Robert R Schick Volker V Amsbaugh Ashley A Aguilar Jorge J Hernandez Mike M Mehran Reza J RJ Riedel Bernhard B Hinkelbein Jochen J

BMC anesthesiology 20140621

<h4>Background</h4>Non-invasive measures of vascular reactivity have emerged to refine cardiovascular risk. However, limited data exists investigating vascular reactivity as a preoperative diagnostic tool for anesthesiologists. In this study, we compare the utility of two non-invasive techniques, Brachial Artery Reactivity Testing (BART) and Digital Thermal Monitoring (DTM), as surrogates for measuring vascular reactivity.<h4>Methods</h4>Following IRB approval, 26 patients scheduled for major th ...[more]

PMID: 24971042

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Project description:IntroductionUltrasound measurements of brachial artery reactivity in response to stagnant ischemia provide estimates of microvascular function and conduit artery endothelial function. We hypothesized that brachial artery reactivity would independently predict severe sepsis and severe sepsis mortality.MethodsThis was a combined case-control and prospective cohort study. We measured brachial artery reactivity in 95 severe sepsis patients admitted to the medical and surgical intensive care units of an academic medical center and in 52 control subjects without acute illness. Measurements were compared in severe sepsis patients versus control subjects and in severe sepsis survivors versus nonsurvivors. Multivariable analyses were also conducted.ResultsHyperemic velocity (centimeters per cardiac cycle) and flow-mediated dilation (percentage) were significantly lower in severe sepsis patients versus control subjects (hyperemic velocity: severe sepsis = 34 (25 to 48) versus controls = 63 (52 to 81), P < 0.001; flow-mediated dilation: severe sepsis = 2.65 (0.81 to 4.79) versus controls = 4.11 (3.06 to 6.78), P < 0.001; values expressed as median (interquartile range)). Hyperemic velocity, but not flow-mediated dilation, was significantly lower in hospital nonsurvivors versus survivors (hyperemic velocity: nonsurvivors = 25 (16 to 28) versus survivors = 39 (30 to 50), P < 0.001; flow-mediated dilation: nonsurvivors = 1.90 (0.68 to 3.41) versus survivors = 2.96 (0.91 to 4.86), P = 0.12). Lower hyperemic velocity was independently associated with hospital mortality in multivariable analysis (odds ratio = 1.11 (95% confidence interval = 1.04 to 1.19) per 1 cm/cardiac cycle decrease in hyperemic velocity; P = 0.003).ConclusionsBrachial artery hyperemic blood velocity is a noninvasive index of microvascular function that independently predicts mortality in severe sepsis. In contrast, brachial artery flow-mediated dilation, reflecting conduit artery endothelial function, was not associated with mortality in our severe sepsis cohort. Brachial artery hyperemic velocity may be a useful measurement to identify patients who could benefit from novel therapies designed to reverse microvascular dysfunction in severe sepsis and to assess the physiologic efficacy of these treatments.

Project description:BackgroundImpaired perfusion indices signal potential microvascular dysfunction preceding atherosclerosis and other cardiometabolic pathologies. Post-occlusive reactive hyperemia (PORH), a vasodilatory response following a mechanically induced ischemia, is a transient increase in perfusion and can assess microvascular function. The greatest blood flow change corresponding to the first minute of hyperemia (represented by time-to-peak, hyperemic velocity, AUC within 1st min) has been shown to indicate microvascular dysfunction. However, the reproducibility of these temporal kinetic indices of the PORH response is unknown. Our aim was to examine the inter- and intra-day reproducibility and standardization of reactive hyperemia, with emphasis on the kinetic indices of PORH, using laser speckle contrast imaging (LSCI) technique.Methods and resultsSeventeen healthy adults (age = 24 ± 3 years) completed three PORH bouts over two lab visits. LSCI region of interest was a standardized 10 cm region on the dominant ventral forearm. A 5-min brachial artery occlusion period induced by inflating an arm cuff to 200 mmHg, preceded a 4-min hyperemic period. Inter- and intra-day reliability and reproducibility of cutaneous vascular conductance (LSCI flux / mean arterial pressure) were determined using intraclass correlation (ICC) and coefficient of variation (CV%). Maximal flow and area under the curve standardized to zero perfusion showed intra- and inter-day reliability (ICC > 0.70). Time to maximal flow (TMF) was not reproducible (inter-day CV = 18%). However, alternative kinetic indices such as 1-min AUC and overshoot rate-of-change (ORC), represented as a piecewise function (at 5s, 10s, 15s, and 20s into hyperemia), were reproducible (CV< 11%). Biological zero was a reliable normalization point.ConclusionPORH measured with LSCI is a reliable assessment of microvascular function. However, TMF or its derived hyperemic velocity are not recommended for longitudinal assessment. Piecewise ORC and 1-min AUC are reliable alternatives to assess the kinetic response of PORH.

Project description:The vascular endothelium is a monolayer of cells that cover the interior of blood vessels and provide both structural and functional roles. The endothelium acts as a barrier, preventing leukocyte adhesion and aggregation, as well as controlling permeability to plasma components. Functionally, the endothelium affects vessel tone. Endothelial dysfunction is an imbalance between the chemical species which regulate vessel tone, thombroresistance, cellular proliferation and mitosis. It is the first step in atherosclerosis and is associated with coronary artery disease, peripheral artery disease, heart failure, hypertension, and hyperlipidemia. The first demonstration of endothelial dysfunction involved direct infusion of acetylcholine and quantitative coronary angiography. Acetylcholine binds to muscarinic receptors on the endothelial cell surface, leading to an increase of intracellular calcium and increased nitric oxide (NO) production. In subjects with an intact endothelium, vasodilation was observed while subjects with endothelial damage experienced paradoxical vasoconstriction. There exists a non-invasive, in vivo method for measuring endothelial function in peripheral arteries using high-resolution B-mode ultrasound. The endothelial function of peripheral arteries is closely related to coronary artery function. This technique measures the percent diameter change in the brachial artery during a period of reactive hyperemia following limb ischemia. This technique, known as endothelium-dependent, flow-mediated vasodilation (FMD) has value in clinical research settings. However, a number of physiological and technical issues can affect the accuracy of the results and appropriate guidelines for the technique have been published. Despite the guidelines, FMD remains heavily operator dependent and presents a steep learning curve. This article presents a standardized method for measuring FMD in the brachial artery on the upper arm and offers suggestions to reduce intra-operator variability.

Project description:BACKGROUND:High brachial blood pressure (BP) is an important cardiovascular risk factor. However major differences in central systolic BP can occur among people with similar brachial systolic BP. It is known that central aortic pressure responses to antihypertensive therapy can differ substantially from brachial BP responses, such that true treatment effects cannot be gauged from conventional brachial BP. OBJECTIVE:The purpose of this study was to examine if adequate control of brachial BP was concordant with central BP control in treated hypertensive subjects. METHODS:Non-invasive acquisition of brachial and central pressures and wave forms was obtained from 100 subjects with systemic arterial hypertension on drug therapy and 50 healthy individuals. After all necessary precautions according to the guidelines, brachial and central pressures and wave forms were measured 3 times at 5 min intervals using an upper arm cuff (AGEDIO K900 HDP Stolberg, Germany). The mean of the last two measurements of each was recorded as representative of brachial and central aortic pressures and wave forms. RESULTS:In 45 of 50 healthy subjects with normotension (41 male, 9 female, mean age 38 years), central systolic BP was <120 mmHg. Five healthy subjects (10%) had falsely normal brachial systolic BP, but raised central systolic BP. Out of 100 patients with known hypertension and on various anti-hypertensive drug combinations, 9 had uncontrolled hypertension (defined as brachial BP of >140/90 mmHg and central systolic BP > 120 mmHg). Ninety-one patients had controlled hypertension as estimated by brachial BP of whom, 37 patients had uncontrolled central BP (systolic BP > 120 mmHg). Thus, brachial BP estimation over-estimated control of hypertension in 41% patients (p < 0.01). Central systolic BP control was inadequate in 9 out of 41 patients (22%) on angiotensin receptor blocking therapy versus 27 out of 31 (87%) patients on beta-blocking therapy (p < 0.05). Thus, there was a marked mismatch with regard to control of hypertension between central and peripheral measurements. CONCLUSION:Central BP measurement provides important information on true prevalence of uncontrolled hypertension in the outpatient setting which is higher than current estimates from brachial BP measurement. Optimal BP control by central BP is far less than observed from peripheral pressure measurement. Residual cardiovascular risk despite adequate control of brachial BP can also be explained by the substantial frequency of uncontrolled hypertension as determined by the central BP in patients with apparently controlled hypertension. Both these conclusions have significant impact on prevalence of uncontrolled hypertension and its proper management. Further studies are required to confirm the current data and to provide evidence that treatment decisions based on measurements of central BP result in better outcomes.

Dataset Information

Brachial artery reactivity and vascular reactive hyperemia for preoperative anaesthesia risk assessment - an observational study.

Background

Methods

Results

Conclusion

Publications

Brachial artery reactivity and vascular reactive hyperemia for preoperative anaesthesia risk assessment - an observational study.

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