When is high blood pressure an emergency?

Blood pressure is considered severe and dangerous when systolic blood pressure is greater than 180 mm Hg and/or diastolic blood pressure is greater than 120 mm Hg.^1-3 It is a hypertensive emergency when severe high blood pressure is accompanied by clinical signs or symptoms of target organ damage. The 2017 American College of Cardiology/American Heart Association (ACC/AHA) hypertension guidelines recommend that adults having a hypertensive emergency should be admitted to an intensive care unit.¹ Their blood pressure requires continuous monitoring as do problems due to target organ damage. People usually need appropriate antihypertensive agents administered intravenously. It is important to reduce blood pressure by up to 25% in the first hour and then to below 160/110 mm Hg over the next two to six hours [Strong Recommendation, Level B-NR]. Reduction of blood pressure in people with no clinical evidence of end-organ damage can be done more gradually over 24 to 48 hours.^1,4

At some time in their life, up to 2% of people with hypertension have a hypertensive emergency.⁵ It can occur in people with chronic hypertension and in those with unknown hypertension.^6,7 In a study of 449 hypertensive crisis patients seen in the emergency department in one year, Zampaglione et al found hypertension was undiagnosed in 23% of the patients.⁷ They found most common presenting symptoms were:

Severe hypertension can cause end-organ damage and represent a clinical hypertensive emergency.³ The brain, heart, and kidneys are the most sensitive organs to acute severe hypertension. Severe hypertension can cause hypertensive encephalopathy, intracranial hemorrhage, or stroke which can cause symptoms of headache, vomiting, visual disturbances, focal neurological signs, and an altered mental status. If untreated, it can lead to seizures, stroke, coma, and death. Hypertensive retinopathy may cause papilledema and may indicate an increased risk of stroke.⁸ Acute severe hypertension can cause acute heart failure, myocardial infarction, and pulmonary edema.³ Symptoms of this include chest pain and dyspnea. Damage to kidneys caused by acute severe hypertension includes impaired filtration.

 ^References

1. Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults: executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Hypertension 2017.
2. Aronow WS. Treatment of hypertensive emergencies. Ann Transl Med 2017; 5 (Suppl 1): S5.
3. McNaughton CD, Self WH, Levy PD, Barrett TW. High-risk patients with hypertension: clinical management options. Clinical medicine reviews in vascular health 2013; 2012 (4): 65-71.
4. Maloberti A, Cassano G, Capsoni N, et al. Therapeutic Approach to Hypertension Urgencies and Emergencies in the Emergency Room. High Blood Press Cardiovasc Prev 2018.
5. Deshmukh A, Kumar G, Kumar N, et al. Effect of Joint National Committee VII report on hospitalizations for hypertensive emergencies in the United States. Am J Cardiol 2011; 108 (9): 1277-1282.
6. Varounis C, Katsi V, Nihoyannopoulos P, Lekakis J, Tousoulis D. Cardiovascular Hypertensive Crisis: Recent Evidence and Review of the Literature. Front Cardiovasc Med 2016; 3: 51.
7. Zampaglione B, Pascale C, Marchisio M, Cavallo-Perin P. Hypertensive urgencies and emergencies. Prevalence and clinical presentation. Hypertension 1996; 27 (1): 144-147.
8. Ong Y-T, Wong TY, Klein R, et al. Hypertensive Retinopathy and Risk of Stroke. Hypertension 2013; 62 (4): 706-711.