Hypertensive emergencies

Nifedipine (Table 3) is a potent vasodilator that selectively dilates resistance vessels and has fewer effects on venous vessels. It does not cause reflex tachycardia during chronic therapy. Nifedipine is one of the first-line choices for black or elderly patients and patients having concomitant angina pectoris, diabetes, or peripheral vascular diseases. Nifedipine, sublingually, is also suitable for the treatment of hypertensive emergencies. Nifedipine does not impair sexual function or worsen blood Hpid profile. The side effects are flushing, headache, and dizziness. 

Diaz oxide (Hyperstat IV) and nitroprusside (Nitropress) are examples of intravenous (IV) drugs that may be used to treat hypertensive emergencies. A hypertensive emergency is a case of extremely high blood pressure that does not respond to conventional antihypertensive drug therapy. 

Hypertensive emergency (no absolute blood pressure range)... 

Must differentiate between hypertensive emergency and urgency... 

Reduce mean arterial pressure (MAP) by 20-25% or to a diastolic blood pressure of 110 mmHg in hypertensive emergencies... 

Hypertensive emergency Target/time to achieve goal... 

Sodium nitroprusside 0.25-10 mcg/kg/minute as IV infusion11 Immediate 1-2 minutes Nausea, vomiting, muscle twitching, sweating, thiocyanate and cyanide intoxication Most hypertensive emergencies use with caution with high intracranial pressure or azotemia... 

Nicardipine hydrochloride 5-15 mg/hour IV 5-10 minutes 15-30 minutes, may exceed 4 hours Tachycardia, headache, flushing, local phlebitis Most hypertensive emergencies except acute heart failure use with caution with coronary ischemia... 

Labetalol hydrochloride 20-80 mg IV bolus every 10 minutes 5-10 minutes 3-6 hours Vomiting, scalp tingling, dizziness, bronchoconstriction, nausea, heart block, orthostatic hypotension Most hypertensive emergencies except acute heart failure... 

Pharmacodynamic interaction resulting in an increase in blood pressure possibly resulting in a hypertensive emergency or stroke avoid this combination. 

The funduscopic examination may reveal arteriolar narrowing, focal arteriolar narrowing, arteriovenous nicking, and retinal hemorrhages, exudates, and infarcts. The presence of papilledema indicates hypertensive emergency requiring rapid treatment. 

Dosing guidelines and adverse effects of parenteral agents for treating hypertensive emergency are listed in Table 10-4. 

Patients with acute stroke should be monitored intensely for the development of neurologic worsening, complications, and adverse effects from treatments. The most common reasons for clinical deterioration in stroke patients are (1) extension of the original lesion in the brain (2) development of cerebral edema and raised intracranial pressure (3) hypertensive emergency (4) infection (e.g., urinary and respiratory tract) (5) venous thromboembolism (6) electrolyte abnormalities and rhythm disturbances and (7) recurrent stroke. The approach to monitoring stroke patients is summarized in Table 13-3. 

Diazoxide and sodium nitroprusside, relative newcomers to the market, are indicated only for hypertensive emergencies. 

Di-receptors (comprising subtypes Di and D5) and D2-receptors (comprising subtypes D2, D3, and D4). The aforementioned actions are mediated mainly by D2 receptors. When given by infusion, dopamine causes dilation of renal and splanchnic arteries. This effect is mediated by Di receptors and is utilized in the treatment of cardiovascular shock and hypertensive emergencies by infusion of dopamine and fenoldopam, respectively. At higher doses, Pi-adrenoceptors and, finally, a-receptors are activated, as evidenced by cardiac stimulation and vasoconstriction, respectively. 

Hypertension, sometimes severe, may occur. (See Nitroprusside and Diazoxide, Parenteral in the Agents for Hypertensive Emergencies section.)... 

Nowadays a broad spectrum of quite specific blood pressure lowering drugs is available which restricts the use of ganglion blockade. There are only a few situations in which the pharmacological blockade autonomous ganglia is clinically useful hypertensive emergencies, controlled hypotension in neurosurgery and in the treatment of pulmonary edema. 

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