336 Medicine Update 57 Hypertensive Emergencies ATUL BHASIN, DG JAIN, RM CHHABRA, RK SINGAL ARTERIAL HYPERTENSION the risk of serious morbidity and death. Blood pressure is often severely raised, diastolic >130 mmHg but is Arterial Hypertension is a medical condition where always a poor correlation between pressure and end- the blood pressure is chronically elevated1. Persistent organ damage. Seriousness of hypertensive emergency hypertension is one of the risk factors for stroke, heart and approach to treatment is determined by end organ attack and heart failure, and is a leading cause of chronic damage. While at the same time hypertensive urgency renal failure. is characterized by a lack of end organ damage. Hyper- tensive emergencies are associated with the following: DEFINITION • Neurological deficits primarily presenting as TIA, Blood pressure is a continuous variable, and risks hypertensive encephalopathy, intracranial of various adverse outcomes rise with it. “Hypertension” hemorrhage and stroke. is usually diagnosed on finding blood pressure above • Cardiovascular complications such as pulmonary 140/90 mmHg measured on both arms on three edema, acute myocardial infarction, adrenergic crisis, occasions over a few weeks. Recently, the JNC VII (The dissecting aortic aneurysm, and eclampsia. Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of • Renal complications as hematuria and progressive High Blood Pressure)2 has defined blood pressure over renal dysfunction. 120/80 mmHg and below 140/90 mmHg as “pre- In these conditions, the blood pressure (BP) should hypertension”. “Prehypertension is not a disease be lowered aggressively over minutes to hours. category. Rather, it is a designation chosen to identify individuals at high risk of developing hypertension (JNC Hypertensive Urgency VII).” Normal blood pressure is 120/80 mmHg. In This is distinguished from hypertensive emergency, patients with diabetes mellitus or kidney disease, studies in which the BP is a potential risk but has not yet caused have shown that blood pressure over 130/80 mmHg acute end-organ damage. Hypertensive crisis is defined should be considered a risk factor and may warrant as having a diastolic BP greater than 120 mmHg that treatment. persists after a period of observation and has optic disk edema, progressive target organ complication, and HYPERTENSIVE EMERGENCIES severe perioperative hypertension. These patients Hypertensive Emergency, also called Hypertensive require BP control over several days to weeks. Crisis, is severe hypertension with acute impairment of Hypertensive urgencies are associated with the an organ system, e.g., central nervous system (CNS) following: malignant hypertension, left ventricular cardiovascular and/or renal, requiring substantial failure, unstable angina, perioperative hypertension and reduction of blood pressure within one hour to avoid pre-eclampsia. Hypertensive Emergencies 337 Severe Hypertension Renal System The third category, severe hypertension, is elevated The renal system is impaired when high BP leads to BP not yet leading to significant organ damage. In these arteriosclerosis, fibrinoid necrosis, and an overall patients, the hypertension does not necessarily require impairment of renal protective autoregulation mecha- treatment during the emergency visit but does require nisms. This may manifest as worsening renal function, close follow-up with a primary care physician for long- hematuria, red blood cell (RBC) cast formation, and/or term BP control. In these cases, beginning antihyper- proteinuria. tensive therapy in the emergency may be appropriate. Hypertensive emergencies and urgencies occur in less than 1% of the 60 million people with hypertension. Emergency Department Considerations Even though not many people with hypertension Optimal control of hypertensive situations balances experience hypertensive crisis, there are still a significant the benefits of immediate decrease in BP against the risk number of events since so many people have of significant decrease in end-organ perfusion. The hypertension. emergency physician must be capable of the following: Frequency • Appropriately evaluating patients with an elevated BP. • In the US: More than 60 million Americans, about • Correctly classifying the hypertension. 25 to 30% of the population, have hypertension. Of these individuals, 70% have mild disease, 20% • Determining the aggressiveness and timing of moderate, and 10% severe hypertension – diastolic therapeutic interventions. BP (DBP) >110 mmHg. Approximately 1-2% develop An important point to remember in the management a hypertensive emergency with end-organ damage. of the patient with any degree of BP elevation is to “treat the patient and not the number”. Morbidity/ Mortality Pathophysiology Morbidity and mortality depend on the extent of end- organ damage on presentation and the degree to which The three major organ systems affected by high BP BP is controlled subsequently. BP control may prevent are the central nervous system, cardiovascular system, progression to end-organ impairment. and renal system. • One-year mortality rate for an untreated hyper- tensive emergency is greater than 90%. Central Nervous System • Five-year survival rate among all patients presenting The CNS is affected as the elevated BP overwhelms with a hypertensive crisis is 74%. the normal cerebral autoregulation. Under normal Race: African Americans have a higher incidence of circumstances, with an increase in BP, cerebral arterioles hypertensive emergencies than Caucasians3. vasoconstrict and cerebral blood flow (CBF) remains constant. During a hypertensive emergency, the elevated Sex: Males are at greater risk of hypertensive BP overwhelms arteriolar control over vasoconstriction emergencies than females. and autoregulation of CBF. This results in transudate Age: Hypertensive emergencies occur most leak across capillaries and continued arteriolar damage. commonly in middle-aged patients. The peak incidence Subsequent fibrinoid necrosis causes normal auto- occurs in those aged 40 to 50 years4. regulatory mechanisms to fail, leading to clinically apparent papilledema, the sine qua non of malignant Etiological Causes of Hypertensive Emergencies hypertension. The end result of loss of autoregulation is Essential Hypertension hypertensive encephalopathy. Renal Cardiovascular System Renal artery stenosis The cardiovascular system is affected as increased Glomerulonephritis cardiac workload leads to cardiac failure; this is accom- Vascular panied by pulmonary edema, myocardial ischemia, or Vasculitis (hemolytic uremic syndrome, thrombotic myocardial infarction. thrombocytopenic purpura) 338 Medicine Update Pregnancy Related with an initial DBP >130 mm Hg had their DBP Preeclampsia fall below critical levels after relaxation without specific treatment6. Eclampsia — Consider the context of the elevated BP (e.g., Pharmacological severe pain often causes increase in BP). Sympathomimetics • Screen for end-organ damage Clonidine, beta blocker withdrawal — Use historical criteria, physical examination steps, Cocaine lab studies, and diagnostic tests to evaluate for Amphetamines cause of hypertension6. Endocrine — Patients with end-organ damage usually require Cushing syndrome admission and rapid lowering of BP using intra- venous (IV) medications. Suggested medication Conn’s syndrome depends on the affected organ system. Pheochromocytoma — Patients without evidence of end-organ effects Rennin secreting adenoma may be discharged with follow-up: Thyrotoxicosis The misconception remains that a patient Neurologic never should be discharged from the ED with 9 Intracranial elevated BP . As a result of this belief, patients are given oral medicines, such as nifedipine, Autoimmune in an effort to lower BP rapidly before Scleroderma Renal Crisis. discharge. This is not indicated and may be dangerous10. Treatment Attempts to temporarily lower BP by using IV vasodilator therapy to achieve a decrease in mean these medicines may result in a precipitous arterial pressure (MAP) of 20 to 25% or a decrease in and difficult-to-correct drop in BP. Should this diastolic blood pressure (DBP) to 100 mmHg to 110 occur, end-organ hypo-perfusion may result. mmHg in the first 2 hours is recommended5. Decreasing Furthermore, patients who present with high the MAP/DBP further should be done more slowly, as BP may have had this elevation for some time one risks decreasing perfusion of end-organs6. Several and may need chronic BP control but may not drugs have proved beneficial in achieving this goal. tolerate rapid return of BP to a “normal” level. Acute lowering of BP in the narrow window Prehospital Care of the ED visit does not necessarily improve • Address the manifestations of a hypertensive long-term morbidity and mortality rates11. emergency, such as chest pain or heart failure. Rapid BP reduction is indicated in the follow- Reduction of BP may not be indicated in the pre- ing circumstances with IV medication12: 7 hospital setting . — Acute myocardial ischemia • Oxygen, frusemide and nitrates may be appropriate. Nitroglycerin • Under most circumstances, attempting to treat Beta-blockers hypertension directly in the prehospital setting is unwise, as rapid lowering of BP can critically Angiotensin-converting enzyme (ACE) decrease end-organ perfusion8. inhibitors (if available). — CHF with pulmonary edema Emergency Department Care Nitroglycerin The fundamental principle in determining the