[The effect of isoflurane on coronary autoregulation in hypothermia].
OBJECTIVE
To analyze the effect of isoflurane on myocardial metabolism and coronary hemodynamics during the reheating phase after heart surgery.


METHODS
Sixteen patients (12 women and 4 men), with cardiac output greater than 0.5 undergoing aortic and/or mitral valve surgery, were studied prospectively. A retrograde thermodilution catheter was placed in the heart and a Swan-Ganz catheter was inserted in the pulmonary artery to determine coronary blood flow and pulmonary wedge pressure, respectively, as well as myocardial and systemic parameters. After surgery, and with hemodynamic variables stable and rectal temperature at 34 +/- 0.5 degrees C, 0.4% isoflurane was administered at the end of expiration. Variables were recorded before administering isoflurane and 20 minutes afterwards.


RESULTS
Isoflurane administration decreased coronary perfusion pressure, coronary vascular resistance, regional myocardial oxygen consumption and myocardial oxygen output. Increases in coronary oxygen saturation and in large coronary vein saturation were also observed. No patient experienced significant changes in ST segment, enzymes or decreased clearance of lactic acid.


CONCLUSIONS
Administering 0.4% isoflurane at the end of expiration effected coronary vasodilation without altering oxygenation or myocardial metabolism. Moreover, no electrocardiographic, enzymatic or metabolic signs of myocardial ischemia were observed.
Tamayo
E
E
Servicio de Anestesiología y Reanimación, Hospital Clínico Universitario, Valladolid.
Gómez
J I
JI
Fernández
A
A
Soria
S
S
Lajo
C
C
Rodríguez
L
L
Cortejoso
J
J
Flores
S
S
Herreros
J
J
D000328:Adult; D000368:Aged; D000769:Anesthesia, Inhalation; D018685:Anesthetics, Inhalation; D006348:Cardiac Surgical Procedures; D003326:Coronary Circulation / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology; D006706:Homeostasis / Q000187:drug effects*; D006801:Humans; D007036:Hypothermia, Induced; D007530:Isoflurane; D008297:Male; D008875:Middle Aged
D018685:Anesthetics, Inhalation; D007530:Isoflurane
Efecto del isoflurano sobre la autorregulación coronaria en hipotermia.