Cerebral hemodynamics during treatment with sodium nitroprusside versus labetalol in malignant hypertension

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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 languageEnglish
Pages (from-to)236-240
Number of pages5
Issue number2
Publication statusPublished - Aug 2008


  • 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

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