When a new patient presents with a blood pressure reading of 175/100 mm Hg or higher and complaints of headache, a hospitalist's first impulse may be to rush him to intensive care and initiate intravenous medications. However, not everyone with extremely high blood pressure meets the criteria for a “hypertensive emergency,” experts caution.
“It's not unusual to see someone whose numbers are really high but they are otherwise okay,” said Matthew V. DeCaro, ACP Member, a cardiologist and director of the coronary care unit at Thomas Jefferson University Hospital in Philadelphia. “The real differentiation between hypertensive emergency and urgency is whether or not there are acute end-organ issues related to the elevations in blood pressure.”
The ability to identify hypertensive emergency is crucial because of the immediate threat to end organs, said David Cherney, MD, PhD, a clinician scientist in the division of nephrology and assistant professor of medicine at the University of Toronto's University Health Network. “Urgency deals with a problem that needs to be dealt with in hours and days versus an emergency that needs to be dealt with in minutes to hours.”
Patients with hypertensive emergencies should be admitted to the ICU for continuous blood pressure monitoring and parenteral drug administration, according to the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure (JNC7).
However, patients diagnosed with hypertensive urgency, who are not at risk for immediate end-organ damage, often can be treated with oral medications outside the hospital with the goal of reducing pressure gradually over one to two days.
In fact, it can be dangerous to treat hypertensive urgency or severe symptomatic hypertension in the same way as a true hypertensive emergency, because lowering blood pressure too rapidly can trigger transient ischemic attack or stroke, said John S. Flanigan, ACP Member, assistant professor in the division of emergency medicine at the University of Maryland School of Medicine in Baltimore. “We try to dissuade internists and surgeons from sending patients to the ED for high blood pressure that is asymptomatic.”
Misuse of resources is another issue, added Dr. DeCaro: “Urgencies don't necessarily need admittance to the hospital, but with emergency not only are you admitting them, you are putting them in the ICU and doing invasive things to them, which is an expensive proposition.”
Making the call
In most cases, a diagnosis can be made based on evidence of evolving end-organ damage, said Dr. Cherney. “With urgency, the blood pressure is high but they have no symptoms or signs that suggest end-organ damage—like chest pain, angina or cerebral issues. With an emergency, there will be some evidence that their high blood pressure is damaging their arteries acutely, and that needs to be reversed immediately to prevent irreparable damage to that end organ.”
Dyspnea, chest pain, and neurologic deficits are some of the most common presenting symptoms in patients with hypertensive emergency, according to a study in the January 1996 Hypertension. The same study found that the most common type of end-organ damage is cerebral infarction, followed by acute pulmonary edema, hypertensive encephalopathy, acute congestive heart failure, and acute myocardial infarction or unstable angina.
Hypertensive emergency is sometimes referred to as “malignant hypertension” but the term has lost favor because it tends to cause confusion, said Dr. Cherney. Malignant is actually a subtype of emergency that relates to damage in the small arteries in the eye, revealed by a funduscopic exam. However, “malignant hypertension” or “accelerated hypertension” is still the required documentation terminology for correct inpatient coding purposes (see Coding Corner, page19).
A thorough physical exam is necessary in order to arrive at an accurate diagnosis, said Dr. Flanigan. In another study, published in the May 2006 Medical Clinics of North America, he and his colleagues recommended the following steps:
- Appropriate chemistry measurements and electrocardiogram;
- Urine toxicology for cocaine metabolites;
- Plain chest radiographs to assess volume status and cardiac size and screen for aortic dissection; and
- Further studies with CT scanning of chest with contrast if aortic dissection is suspected.
Once a diagnosis of hypertensive emergency seems likely, physicians must quickly initiate drug therapy targeted to the end organ affected, said Dr. Flanigan. The standard procedure for emergencies is to reduce pressure by no more than 25% in the first hour; lower to 160/100-110 mm Hg over the next two to six hours; and, if the patient is stable, gradually reduce pressure to a normal level over the next 24-48 hours, according to JNC7.
“The pressure needs to be lowered relatively quickly, but not by too much and not too fast because the organs involved may lose their ability to autoregulate after they have been exposed to very high blood pressure for a prolonged period,” said Dr. Cherney.
Reducing blood pressure is a therapeutic goal for all patients with emergencies but individual targets depend on the organ affected, said Dr. Flanigan. For example, you should not exceed a 20% reduction in pressure in the case of hypertensive encephalopathy, cerebrovascular accident or intracranial hemorrhage, he noted in the Medical Clinics article. Patients in these categories often experience fluctuations in pressure and are at risk for hypoperfusion of the brain.
Most clinicians are attuned to the need for gradual reduction in blood pressure over the first two days, said Dr. DeCaro, but make the mistake of starting the patient on too many oral medications too quickly. Introduce oral medications gradually so that the patient's body has a chance to adjust, he advised. If you increase doses or add medications too quickly, the patient's blood pressure could plummet, putting him at risk for stroke.
“You get to the point where you are increasing doses or adding medications more quickly than the medications have the chance to achieve steady state,” said Dr. DeCaro. “The pressure looks good, so you send them out of the ICU—then all of the medications kick in at once and the pressure goes too low.”
Remember that even if a patient's medication history lists six drugs they were taking before they were admitted, you don't know whether the patient was compliant, he added. Starting all six at once could cause their pressure to drop too rapidly. Physicians can refer to the most recent JNC guidelines for guidance on drug selection, dosage and other considerations. The guidelines list six vasodilators (sodium nitroprusside, nicardipine hydrochloride, fenoldopam mesylate, nitroglycerin, enalaprilat and hydralazine hydrochloride) and three adrenergic inhibitors (labetalol hydrochloride, esmolol hydrochloride and phentolamine) commonly used for treatment of emergencies.
Some cases of hypertensive emergency call for modification of standard treatment methods, for example, if a patient has a stroke, heart failure, chronic kidney disease or aortic dissection. Consider the following points in these special situations, experts said:
- Heart failure. Most hypertensive emergency patients should not take diuretics because of the dehydrating effect, but nitroglycerin and diuretics can help heart failure patients by reducing hormones causing the high blood pressure, said Dr. Cherney.
- Acute heart failure. Don't use labetalol because it has beta-blocking activity that can further exacerbate heart failure, he added.
- Chronic kidney disease. Avoid using an ACE inhibitor, which can make kidney function worse and cause hyperkalemia, Dr. Cherney said.
- Aortic dissection. This is a life-threatening problem, so it's appropriate to violate the 25% rule and lower blood pressure more quickly (to below 120/80 mm Hg or less), said Dr. DeCaro.
- Ischemic stroke. Treat these patients less aggressively than guidelines suggest, said Dr. DeCaro. There is no official consensus on whether blood pressure should be lowered at all in stroke patients because doing so may reduce cerebral blood flow.
Care is also required in the preparation to and follow-up from hospital discharge following a hypertensive emergency, experts said.
“The patient needs to be transitioned to oral medications,” said Dr. Cherney. “If the transition is too fast or you didn't give them a high enough dose, their blood pressure will rebound and they will relapse.”
It's also important for hospitalists to work with specialists, especially for patients with concurrent conditions like kidney disease or heart failure, to titrate medications properly, he said.
As well, it's crucial to discuss the treatment plan with the patient and maintain close communication, said Dr. DeCaro. He asks his patients to buy a blood pressure cuff and keep a log of their pressure several days a week, which they email to him so he can make adjustments without them coming to the office.
The key is arming patients with information and preparing them to take an active role in the ongoing management of their condition, he added. “Patients need to know when they leave the hospital and get back to normal activities and diet that their pressures commonly will increase compared to how they were controlled in the hospital,” Dr. DeCaro said.