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


METHODS
This was a prospective observational study.


METHODS
A university teaching hospital.


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


METHODS
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.


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.
Harris
Bryan
B
Department of Anesthesiology, University of California, San Diego, CA 92103, USA. brharris@UCSD.edu <brharris@UCSD.edu>
Manecke
Gerard R
GR
Niemann
Jared
J
Madani
Michael
M
Jamieson
Stuart
S
D000328:Adult; D000368:Aged; D018686:Anesthetics, Intravenous / Q000008:administration & dosage*; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D002315:Cardiopulmonary Bypass / Q000379:methods; D050792:Circulatory Arrest, Deep Hypothermia Induced / Q000379:methods*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005263:Femoral Artery / Q000187:drug effects* / Q000503:physiopathology; D005500:Follow-Up Studies; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000601:surgery; D013874:Thiopental / Q000008:administration & dosage*; D016896:Treatment Outcome
D018686:Anesthetics, Intravenous; D013874:Thiopental