The effect of aminophylline on loss of consciousness, bispectral index, propofol requirement, and minimum alveolar concentration of desflurane in volunteers.
BACKGROUND
Adenosine is a soporific neuromodulator; aminophylline, which is clinically used as a bronchodilator, antagonizes the action of adenosine in the central nervous system. Thus, we tested the hypothesis that aminophylline delays loss of consciousness (LOC) and speeds recovery of consciousness (ROC) with propofol anesthesia, and that aminophylline increases the minimum alveolar concentration (MAC) of desflurane.


METHODS
In this double-blind crossover study, volunteers were randomized to either aminophylline or saline on different days. Aminophylline 6 mg/kg was given IV, followed by 1.5 mg x kg(-1) x h(-1) throughout the study day. After 1 h of aminophylline or saline administration, propofol 200 mg was given at a rate of 20 mg/min. The bispectral index was continuously monitored, as were times to LOC and ROC. After recovery from propofol, general anesthesia was induced with sevoflurane and subsequently maintained with desflurane. The Dixon "up-and-down" method was used to determine MAC in each volunteer after repeated tetanic electrical stimulation.


RESULTS
Eight volunteers completed both study days. Time to LOC was prolonged by aminophylline compared with saline (mean +/- SD) (7.7 +/- 2.03 min vs 5.1 +/- 0.75 s, respectively, P = 0.011). The total propofol dose at LOC was larger with aminophylline (2.2 +/- 0.9 vs 1.4 +/- 0.4 mg/kg, P = 0.01), and the time to ROC was shorter (6.18 +/- 3.96 vs 12.2 +/- 4.73 min, P = 0.035). The minimum bispectral index was greater with aminophylline (51 +/- 15 vs 38 +/- 9, P = 0.034). There was no difference in MAC.


CONCLUSIONS
Aminophylline decreases the sedative effects of propofol but does not affect MAC of desflurane as determined by tetanic electrical stimulation.
Turan
Alparslan
A
Department of Outcomes Research, Cleveland Clinic, Cleveland, Ohio 44195, USA. alparslanturan@yahoo.co
Kasuya
Yusuke
Y
Govinda
Raghavendra
R
Obal
Detlef
D
Rauch
Stefan
S
Dalton
Jarrod E
JE
Akça
Ozan
O
Sessler
Daniel I
DI
D000241:Adenosine / Q000037:antagonists & inhibitors; D000293:Adolescent; D000328:Adult; D000628:Aminophylline / Q000494:pharmacology*; D000762:Anesthesia Recovery Period; D000768:Anesthesia, General; D018685:Anesthetics, Inhalation / Q000493:pharmacokinetics*; D018686:Anesthetics, Intravenous / Q000008:administration & dosage*; D003243:Consciousness / Q000187:drug effects*; D056805:Consciousness Monitors; D018592:Cross-Over Studies; D000077335:Desflurane; D004311:Double-Blind Method; D006801:Humans; D007530:Isoflurane / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D008297:Male; D015742:Propofol / Q000008:administration & dosage*; D011650:Pulmonary Alveoli / Q000737:chemistry*; D055815:Young Adult
D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D000628:Aminophylline; D000077335:Desflurane; D007530:Isoflurane; D000241:Adenosine; D015742:Propofol