Considerations for Accurate Blood Pressure Measurement in Clinical Care and Research

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PAGE 274 JOURNAL OF VASCULAR NURSING DECEMBER 2019 www.sciencedirect.com/journal/journal-of-vascular-nursing Clinical Column

Considerations for accurate blood pressure measurement in clinical care and research

Rebecca J. L. Brown, MEd, MN, RN, PHN, Kathleen Rich, PhD, RN, CCNS, CCRN-CSC, CNN, and Diane Treat-Jacobson, PhD, RN, FSVM, FAAN, FAHA

INTRODUCTION ment may still be inaccurate depending on placement of a correctly sized cuff. This may be particularly problematic for pa- Blood pressure measurement is an integral part of vital signs tients who are obese. The shape of the arm may be more conical assessment. Blood pressure is directly related to vascular mortal- and less cylindrical, resulting in substantially different arm cir- ity after age 40 years and for blood pressure of 115/75 mm Hg.1 cumferences at the proximal and distal cuff borders. This results All nurses learn this basic assessment skill; however, in our in unequal cuff inflation even when the correct cuff size is used. changing population and against the time constraints imposed This has implications beyond hypertension assessment. For by the health care system, performing an accurate and thorough example, patients undergoing an ankle brachial index (ABI) blood pressure measurement can be challenging. The most recent can be falsely diagnosed with peripheral artery disease (PAD) blood pressure management guideline provides a detailed check- if an ill-fitting cuff is used on the arms, and thus artificially list of essential requirements needed to obtain an accurate blood inflating the blood pressure. Pain during measurement also con- pressure measurement (www-ahajournals-org).2 Beyond these tributes to inaccurate blood pressure measurement. Pain with elements, challenges remain and are magnified in clinical prac- blood pressure measurement is often related to pinching loose tice and research. The purpose of this clinical column is to high- or excess skin with inflation of the cuff. The cuff must be applied light common problems seen in practice and research using case in congruence with the national guidelines and manufacturers’ examples, review disease processes associated with blood pres- instructions while minimizing discomfort. With conical arm sure abnormalities, and discuss implications of inaccurate blood habitus, it may be inaccurate to measure brachial pressures. Leb- pressure assessment. Common problems include 1) improper lanc and colleagues have demonstrated high correlation of fore- cuff size, 2) cuff placement, and 3) not measuring both arms. arm blood pressure with intraarterial blood pressure measurement.3 The guidelines do not address using alternative Correct cuff size and correct application of cuff sites to obtain a blood pressure such as the foot or forearm, though forearm blood pressures have been documented to be Perhaps, the most problematic issue with blood pressure 4 assessment is improper cuff size. According to the national widely used in primary care and emergency departments. It is guidelines, the circumference is to be measured at the midpoint important to note that obtaining a blood pressure at the dorsalis between the acromion and olecranon processes and the bladder pedis or posterior tibial arteries may be somewhat elevated of the cuff is to encircle 80% of the patient’s arm. Table 9 of compared to the brachial pressures in the absence of PAD, significantly higher relative to the brachial pressures with calcified ves- the guidelines provides precise measurement parameters for 5 cuff size. Despite these clear guidelines, blood pressure measure- sels, and lower in those with PAD. In general, the ankle pressure should not be used to obtain a blood pressure unless no other op- tion is available. From the ---. Corresponding author: Rebecca J.L. Brown, MEd, MN, RN, PHN, PhD Candidate, CTSI TL1 Predoctoral Fellow, 5-140 Measure both arms Weaver Densford Hall, 308 Harvard St. SE, Minneapolis, Atherosclerosis in the upper extremities can lead to lowering MN 55455 (E-mail: [email protected]). of the brachial pressure in one or both arms. According to the national guidelines, blood pressure should be obtained in both 1062-0303/$36.00 arms. Blood pressure may vary significantly between arms and Copyright Ó 2019 Published by Elsevier Inc. on behalf of the So- antihypertensive therapies should be based on the highest blood ciety for Vascular Nursing, Inc. pressure obtained. A brachial blood pressure difference of https://doi.org/10.1016/j.jvn.2019.12.003 15 mmHg is one clinical criterion for subclavian-vertebral artery steal syndrome.6 Subclavian-vertebral artery steal syndrome Vol. XXXVII No. 4 JOURNAL OF VASCULAR NURSING PAGE 275 www.sciencedirect.com/journal/journal-of-vascular-nursing occurs when a stenosis or occlusion of the subclavian or brachio- Had her ABI not been repeated at this visit, she could have cephalic arteries causes flow to the vertebral arteries to reverse, received a false diagnosis of PAD. This could have led to unnec- particularly during physical activity involving the upper extrem- essary, costly treatment and angst for the patient. ities. Apart from steal syndrome, there are additional clinical im- Finally, we report a case of a study participant who under- plications of interarm pressure differences in the prediction and went an ABI. She reported no hypertension and was not on medi- detection of coronary artery disease, peripheral artery disease, cation. Her right brachial blood pressure was 124 mmHg, which and mortality that have yet to be fully appreciated or explored was reportedly her ‘‘usual’’ blood pressure. Her left brachial in terms of screening potential. An interarm difference of $ blood pressure was 202 mmHg and therefore was deemed ineli- 10 mm Hg in systolic blood pressure is associated with an gible for the study due to high blood pressure. Her health care increased risk of all-cause and cardiovascular-related mortality provider treated her blood pressure based on the lower of the and morbidity.7 two arm pressures. Had both arms been assessed, this would have been revealed and prevented prolonged exposure to sustain Case studies high blood pressure in her left arm and elsewhere. We present a case of a study participant who was found to CONCLUSION have significantly lower blood pressure in the physiology labora- tory than in her primary care doctor’s office. She was being These cases reinforce the importance of proper blood pres- treated for hypertension with typical blood pressures between sure measurement, which includes but is not limited to selecting 120 and 130 s/80 s mmHg when adherent to her antihypertension the correct cuff size for the patient, selecting the best approach to prescription. An ABI was conducted. Supine right and left apply the blood pressure cuff, the location of where to apply the brachial pressures were 88 mmHg and 92 mmHg, respectively. cuff, and the assessment of the blood pressure in both arms. Following the ABI, seated pressure measurements were obtained Please refer to Table 8 from the latest national guidelines for a according to the national practice guidelines. Her seated blood comprehensive checklist for proper blood pressure measurement. pressure was 104/72 mmHg. The participant reported dissatisfac- Blood pressure is one of the most important assessments health tion with extra skin on the posterolateral aspect of her arm, was care teams measure. Although this measurement technique is obese, and had lost approximately 25 pounds over the past six tightly standardized, individualization is still necessary to ensure months. Also of note, she reported that this was the first time accurate results. she was not pinched by the cuff during blood pressure measure- ACKNOWLEDGMENTS ment (supine and seated blood pressure measurements) and reported that she often has light-headedness with change in This publication was supported by the National Institutes of position. It is possible that pain during clinic visit blood pressures Health’s National Center for Advancing Translational Sci- may have artificially elevated her blood pressure and resulted in ences, grants TL1R002493 and UL1TR002494. The content overprescription of antihypertensive medication. is solely the responsibility of the authors and does not neces- This was a one-time visit and, according to the national sarily represent the official views of the National Institutes of guidelines, blood pressure level should be calculated using an Health’s National Center for Advancing Translational Sci- average of at least two or more blood pressures obtained on at ences. The authors have no conflicts of interest. least two or more separate visits. Therefore, we do not suggest that this individual’s treatment should be adjusted based on this REFERENCES sole encounter. However, this encounter provides valuable les- sons and reminders that we should all consider when obtaining 1. 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