Abstract
In patients with malignant hypertension, immediate blood pressure reduction is indicated to prevent further organ damage. Because cerebral autoregulatory capacity is impaired in these patients, a pharmacologically induced decline of blood pressure reduces cerebral blood flow with the danger of cerebral hypoperfusion. We compared the reduction in transcranial Doppler-determined middle cerebral artery blood velocity during blood pressure lowering with sodium nitroprusside with that of labetalol. Therefore, in 15 patients, fulfilling World Health Organization criteria for malignant hypertension, beat-to-beat mean arterial pressure? systemic vascular resistance (Modelflow), mean middle cerebral artery blood velocity, and cerebrovascular resistance index (mean blood pressure:mean middle cerebral artery blood flow velocity ratio), were monitored during treatment with sodium nitroprusside (n=8) or labetalol (n=7). The reduction in mean arterial blood pressure with sodium nitroprusside (-28+/-3%; mean+/-SEM) and labetalol (-28+/-4%) was comparable. With labetalol, both systemic and cerebral vascular resistance decreased proportionally (-13+/-10% and -17+/-5%), whereas with sodium nitroprusside, the decline in systemic vascular resistance was larger than that in cerebral vascular resistance (-53+/-4% and -7+/-4%). The rate of reduction in middle cerebral artery blood velocity was smaller with labetalol than with sodium nitroprusside (0.45+/-0.05% versus 0.78+/-0.04% cm.s(-1).%mm Hg(-1); P <0.05). In conclusion, sodium nitroprusside reduced systemic vascular resistance rather than cerebral vascular resistance with a larger rate of reduction in middle cerebral artery blood velocity, suggesting a preferential blood flow to the low resistance systemic vascular bed rather than the cerebral vascular bed
Original language | English |
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Pages (from-to) | 236-240 |
Number of pages | 5 |
Journal | Hypertension |
Volume | 52 |
Issue number | 2 |
DOIs | |
Publication status | Published - Aug 2008 |
Keywords
- Adult
- Analysis of Variance
- Antihypertensive Agents/administration & dosage
- Blood Pressure Determination
- Cerebrovascular Circulation/drug effects
- Dose-Response Relationship, Drug
- Drug Administration Schedule
- Electrocardiography
- Female
- Follow-Up Studies
- Hemodynamics/drug effects
- Humans
- Hypertension, Malignant/diagnosis
- Infusions, Intravenous
- Labetalol/administration & dosage
- Male
- Middle Aged
- Nitroprusside/administration & dosage
- Probability
- Prospective Studies
- Risk Assessment
- Severity of Illness Index
- Statistics, Nonparametric
- Survival Rate
- Treatment Outcome
- Ultrasonography, Doppler, Transcranial
- Vascular Resistance/drug effects