Deep hypothermia and the vascular response to thiopental.

Abstract

OBJECTIVE:

The vascular response to intravenous thiopental in patients on cardiopulmonary bypass during deep hypothermia was examined.

DESIGN:

This was a prospective observational study.

SETTING:

A university teaching hospital.

PARTICIPANTS:

Twenty-one consecutive adult patients undergoing pulmonary thromboendarterectomy during which deep hypothermic circulatory arrest was instituted.

INTERVENTIONS:

Immediately before circulatory arrest, each patient was administered a 500-mg dose of thiopental intravenously. Arterial blood pressure was monitored and recorded by using a femoral artery catheter and serum electrolytes, acid-base status and arterial hematocrit were determined immediately before the administration of thiopental.

MEASUREMENTS AND MAIN RESULTS:

Thiopental was associated with a dose-related increase in mean arterial pressure of 32 +/- 11 mmHg (p < 0.0001). Thiopental also resulted in an increase in arterial pH of 0.08 +/- 0.03. A positive correlation between the magnitude of the pH change and the magnitude of the hypertensive response was suggested but did not reach statistical significance (p = 0.066). Of the other factors investigated, only serum-ionized calcium had a statistically significant association with the vascular response in that higher ionized calcium was associated with less hypertensive response (p = 0.014).

CONCLUSIONS:

The administration of thiopental to deeply hypothermic patients during cardiopulmonary bypass is associated with a dramatic increase in mean arterial blood pressure. The mechanism responsible for this vasoconstrictive response may involve thiopental's potentiation of the effects of norepinephrine in the peripheral vasculature.

• Authors: Bryan Harris, Gerard R Manecke Jr, Jared Niemann, Michael Madani, Stuart Jamieson
• Journal: Journal of cardiothoracic and vascular anesthesia (J Cardiothorac Vasc Anesth) Vol. 20 Issue 5 Pg. 678-83 (Oct 2006) ISSN: 1053-0770 [Print] United States
• PMID: 17023288 (Publication Type: Journal Article)

Chemical References

• Anesthetics, Intravenous
• Thiopental

Topics

• Adult
• Aged
• Anesthetics, Intravenous (administration & dosage)
• Blood Pressure (drug effects, physiology)
• Cardiopulmonary Bypass (methods)
• Circulatory Arrest, Deep Hypothermia Induced (methods)
• Dose-Response Relationship, Drug
• Female
• Femoral Artery (drug effects, physiopathology)
• Follow-Up Studies
• Humans
• Injections, Intravenous
• Male
• Middle Aged
• Prospective Studies
• Pulmonary Embolism (surgery)
• Thiopental (administration & dosage)
• Treatment Outcome