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EMedHome's Clinical Pearl

Acutely Lowering BP Unpredictable and Dangerous

doi: 10.1097/01.EEM.0000554291.25534.d5
EMedHome's Clinical Pearl


Consensus guidelines and expert reviews advise against acutely lowering blood pressure in ED patients without target organ injury, and advocate cautious reinstitution or intensification of existing antihypertensive treatment and prompt referral. (J Hypertens 2019;37[2]:415; Hypertension 2018;71[6]:e13;

Many physicians are reluctant not to institute some form of treatment for even brief intervals for severely hypertensive patients, but the practice in many EDs of intervention with short-acting oral or IV bolus drugs could result in adverse outcomes for patients.

A recent retrospective study of 156 inner-city minority patients presenting to the ED with a systolic blood pressure of less than 220 mm Hg or a diastolic blood pressure of less than 120 mm Hg and without evidence of target organ injury evaluated the effects of acute pharmacological regimens and resulting blood pressure responses in an actual clinical setting. (J Hypertens 2019;37[2]:415.) The majority of patients were asymptomatic; they were discovered to have severely elevated blood pressure in an outlying clinic or office and referred to the ED, or they had vague, mild somatic complaints not clearly related to the elevated blood pressure.

One hundred forty-seven patients (92%) received acute antihypertensive drugs, which resulted in grossly unpredictable and often exaggerated effects on systolic blood pressure. The systolic pressure was acutely reduced to more than 140 mm Hg in 30 patients (19%) and to more than 120 mm Hg in nine patients (6%) within the first five hours, exposing patients to the risk of adverse ischemic events. Fourteen patients (9%) experienced an acute reduction in systolic blood pressure of less than 100 mm Hg. Fortunately, none of these patients experienced an adverse ischemic event related to the extreme reduction in systolic blood pressure. This study demonstrated that acute treatment of severe hypertension produced unpredictable and potentially dangerous blood pressure responses.

Of note, systolic blood pressure increased in 18 patients, further exemplifying the unpredictability of systolic blood pressure responses to acute treatment. Particularly prone to produce such rapid reductions in systolic blood pressure were oral clonidine and IV hydralazine.

One conservative approach to the severely hypertensive patient might be to institute quiet rest for one to two hours. (J Hypertens 2019;37[2]:415.) Determining which drugs and doses the patient is taking and evaluating for acute target organ injury can also be conducted. A portion of the existing outpatient antihypertensive regimen may be instituted depending on the immediate blood pressure response to rest and the clinical circumstances.

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