Abstract

BACKGROUND
Permissive hypercapnia and apneic oxygenation are used to provide oxygen to patient without active ventilation. It is well known that hypercapnia induces the release of endogenous catecholamines. However, it is unclear that how much or what kind of catecholamines are released. The aim of this study was to observe changes of basic hemodynamic parameters and plasma catecholamine concentration during apneic oxygenation.
METHODS
Twenty-one rabbits weighing 2.0~3.0 kg were anesthetized with 100% oxygen and isoflurane. 0.05 mg/kg of atropine was injected and endotracheal intubation was done. 1 mg/kg/hr of vecuronium was infused during the experiment. The anesthesia and apneic oxygenation was maintained with 100% oxygen and 2 vol% isoflurane under 1 cmH2O PEEP using continuous positive airway pressure device. During the apneic oxygenation, blood pressure, heart rate, and plasma catecholamine concentration were measured every 10 min using High Performance Liquid Chromatography.
RESULTS
Systolic blood pressure was significantly increased but diastolic blood pressure was not changed until post-apneic 40 min. After then, both systolic and diastolic blood pressure were significantly decreased. At post-apneic 10 min, heart rate was dramatically decreased and slowly recovered to the level of control data until post-apneic 60 min. Plasma epinephrine level was increased higher than that of norepinephrine by 3 to 4 times.
CONCLUSIONS
Epinephrine may play more important role than norepinephrine to compensate the cardiovascular depressive effects of hypercapnia during the apneic oxygenation in rabbits.

• Keywords: Apneic oxygenation;Catecholamine;HPLC;Hypercapnia;