Hypoxemia and hemodynamic changes during the hypercarbia stimulation test.
The hypercarbia stimulation test is a valuable technique to document the absence of brainstem responsiveness to elevated levels of carbon dioxide (PCO2); however, its application has been limited by concern that hypoxemia may induce cardiovascular instability. We investigated hemodynamic and oxygen (PO2) changes in 19 patients: group 1 (17 patients) had no spontaneous ventilations at PCO2 values ranging from 37-129 torr; group 2 (2 patients) had spontaneous ventilations at less than 38 torr. Group 1 was separated into 2 subgroups: A (10 patients) with PO2 greater than 153 torr and B (7 patients) with PO2 less than 80 torr. Hemodynamic changes (less than 10% variation in baseline pulse and blood pressure) occurred in 9 of 10 patients in group 1A and all patients in Group 1B. Mean differences in pulse and blood pressure changes between these groups were not significant; therefore, pulse and blood pressure changes are not predictive of hypoxemia and hypercarbia is not necessary to induce spontaneous ventilation in patients with intact medullary function.
Riviello
J J
JJ
Section of Child Neurology, St. Christopher's Hospital for Children; Philadelphia, PA 19133.
Sapin
J I
JI
Brown
L W
LW
Truex
R C
RC
Grover
W D
WD
D000293:Adolescent; D001926:Brain Death / Q000175:diagnosis*; D001927:Brain Diseases / Q000175:diagnosis / Q000503:physiopathology*; D001933:Brain Stem / Q000503:physiopathology*; D002245:Carbon Dioxide / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D007223:Infant
D002245:Carbon Dioxide