michigan hypertension core curriculum - State of Michigan

ACUTE KIDNEY INJURY (AKI)
In addition to papilledema, acute renal failure/ AKI were the earliest described TOD caused
by severely elevated BP (“malignant hypertension”). The endothelial damage and arteriolar fibrinoid
necrosis mirrors that seen in the heart, brain, and other organs. The syndrome is recognized by
the combination of acutely decreased GFR, proteinuria, anemia, thrombocytopenia, and presence
of schistocytes and other red cell fragments. It can be confused with hemolytic uremic syndrome
or TTP, although the thrombocytopenia is generally less severe than in these other thrombotic
microangiopathies while the BP elevation is usually more severe. Treatment principles are the same
as in other types of TOD – rapid reduction of BP to levels that stop further vascular damage while
maintaining perfusion of organs that generally have impaired autoregulation. Nitroprusside is commonly
used although the dose and duration of use must be monitored and to avoid cyanide or thiacyanate
toxicity. The simultaneous infusion of thiosulate can reduce but not eliminate the threat of this toxicity.
Some advocate the use of the dopamine-1 receptor antagonist fenoldopam mesylate in this setting, not
only to avoid toxicity but because it may increase renal blood flow and sodium excretion.
PREECLAMPSIA AND ECLAMPSIA
The treatment of pre-eclampsia and eclampsia is governed by the need to protect the health
of both the mother and fetus. The role of medical management, discussed in a later section of this
chapter, is only a temporizing measure until the fetus can be safely delivered. The choice of drugs is
dictated both by efficacy and avoidance of fetal toxicity or harm. Drugs accepted as safe in this setting
primarily include labetolol, nifedipine, nicardipine, and hydralazine. 17 Magnesium sulfate, generally
indicated when a diagnosis of eclampsia or severe pre-eclampsia is entertained, is used primarily for
prophylaxis against seizures, not management of hypertension per se.
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CONCLUSIONS:
The mortality and morbidity associated with hypertensive emergency and urgency is
considerable in untreated patients. At the same time, there is potential for serious adverse effects of
treatment and specific recommendations remain opinion based at this time. There are no definitive
studies establishing the ideal levels or rates of blood pressure lowering. In hypertensive emergencies,
a compromise must be reached between preventing additional target organ damage while maintaining
perfusion. In each case choice of anti-hypertensive medications needs to be individualized.
1. Zampaglione B, Pascale C, Marchisio M, Cavallo-Perin P. Hypertensive urgencies and
emergencies. Prevalence and clinical presentation. Hypertension 1996; 27(1): 144-147.
2. Bennett NM, Shea S. Hypertensive emergency: case criteria, sociodemographic profile, and
previous care of 100 cases. Am J Public Health 1988; 78(6): 636-640.
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