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October 23, 2024
Written by Laura Murphy
Hypertensive emergencies are associated with high morbidity and mortality and require specific strategies to diminish pressure-mediated organ injury, depending on the type of hypertensive presentation.
A little goes a long way
Hypertensive emergency is new or worsening organ injury with severely elevated BP (usually 220/110) or an accelerated rise in blood pressure. This term includes a heterogeneous group of conditions (cerebrovascular, cardiovascular, ophthalmologic, hematologic, and renal systems), for which there are specific treatment considerations. It should be differentiated from asymptomatic hypertension or transient reactive elevation in BP, where rapid lowering of BP may be harmful. While the incidence of hypertensive emergency is low (~ 0.5% of emergency department visits), in-hospital mortality is high (~10%).
An essential, but often overlooked, step is accurate measurement of blood pressure (proper cuff size and positioning) prior to initiation of treatment. Clinical evaluation includes evaluation of symptoms and physical exam (neurologic and cardiovascular symptoms, visual acuity and fundoscopic exam looking for cotton-wool spots, flame hemorrhages, papilledema). ECG and laboratory testing (CBC, BMP, cardiac biomarkers) can be helpful, and imaging should be targeted to suspected clinical entity. Differentiate hyperadrenergic states (drug-induced, pheochromocytoma) or aortic dissection, where benefit from unique treatments is needed, but evaluation for secondary causes of hypertension can be deferred during initial evaluation.
Chronic hypertension leads to pathologic remodeling that shifts the autoregulation curve such that patients can tolerate a mean arterial pressure of 150 mm Hg and above. Generally, infusions are best for initial management, and invasive blood pressure monitoring may be indicated for intensive treatment. Treatment should balance the effects of lowering blood pressure with negative effects of organ hypoperfusion in patients with altered autoregulatory mechanisms; generally, initial reduction of mean arterial blood pressure by 20-25% is advised. Authors recommend avoiding IV hydralazine and nitroprusside, given the potential for sudden drops in blood pressure exceeding target BP. For drops in BP beyond extended target, consider fluid resuscitation due to pressure natriuresis from severe arterial hypertension.
The article reviews evaluation and diagnosis of specific diagnoses, and treatment principles are summarized in Table 2 below:
Finally, barriers to outpatient anti-hypertensive therapy should be addressed to reduce risk in the future; approximately 65% of patients with severe hypertension have uncontrolled hypertension at 6 months after their ED visit.
How will this change my practice?
This is not likely to change my practice much, as I generally avoid IV antihypertensives unless it is true hypertensive emergency. That said, it was a great review of physiology and best practices for hypertensive emergency and the heterogeneous diagnoses that make up this clinical entity. It also reminded me of the importance of differentiating hypertensive emergency from other cases of severely elevated BP.
Source
Evaluation and management of hypertensive emergency. BMJ. 2024 Jul 26;386:e077205. doi: 10.1136/bmj-2023-077205. PMID: 39059997.
