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Chapter 4. Hypertensive Emergencies and Urgencies

R. Phillip Dellinger, MD, MSc, FCCP;; Jean-Sebastien Rachoin, MD
DOI: 10.1378/critcare.21.4
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Sections

Objectives 
  • Be able to recognize a hypertensive emergency.

  • Have insight into characteristics of antihypertensive medications that allow matching them to specific types of hypertensive emergencies.

  • Know toxicities and side effects of antihypertensive drugs.

Synopsis 

A hypertensive emergency is defined as hypertension associated with acute organ dysfunction. In the presence of a hypertensive emergency, the goal BP over the first hour should be a reduction in mean arterial pressure no greater than 20% to 25% (in consideration of the effects of BP lowering on the cerebrovascular blood flow autoregulation curve, which is likely to be shifted to the right in these patients). Exceptions to the 20% to 25% rule include unclipped or uncoiled aneurismal hemorrhage associated with hypertension and aortic dissection. There are many drugs used to treat hypertensive emergencies. Intravenous nicardipine acts primarily as an arterial vasodilator and has a quick onset of action but a slower offset. Clevidipine is a newer agent similar to nicardipine but with a quicker offset. Intravenous labetalol is a combined αβ-blocker, and esmolol is an IV β-blocker, both of potential utility. Sodium nitroprusside has stood the test of time as a reliable agent for effective treatment for hypertensive emergencies, although there should be some caution as to cyanide toxicity when exceeding US Food and Drug Administration labeling instructions or in patients with renal insufficiency. Specific clinical situations that require special considerations for therapy include hypertensive encephalopathy, acute aortic dissection, acute ischemic stroke, and intracerebral/subarachnoid hemorrhage. Treatment of catecholamine-induced hypertension is best managed with benzodiazepines along with nicardipine or verapamil. postoperative hypertension is associated with wound hemorrhage and other complications.

References

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