Local application of halothane, isoflurane or sevoflurane increases the response to an electrical stimulus in humans.
Volatile anesthetics may interfere with pain perception. This study investigates the effect of halothane, isoflurane and sevoflurane when applied locally, to the response of an electrical stimulus.


METHODS
In this randomized control double-blind crossover study 70 volunteers were studied. In experiment 1 (30 subjects), equipotent liquid volumes of halothane 1 ml, isoflurane 1.5 ml and sevoflurane 2.7 ml were randomly applied on one forearm for 30 minutes. The other forearm received water. Both forearms were exposed to an electrical stimulus. The experiment was repeated the following day in a reverse fashion. In experiments 2 (20 subjects) and 3 (20 subjects) the response to the same stimulus was tested after local application of 2, 4, and 6 ml of halothane or 5 ml of sevoflurane respectively.


RESULTS
Low doses of the three anesthetics were associated with an increased response to the electrical stimulus (F = 8.940, df = 1,174, P = 0.003). Higher doses of halothane and sevoflurane had no effect on the response (F = 2.358, df = 1,114, P = 0.127 and t = 0.840, df = 19, P = 0.411 respectively).


CONCLUSIONS
Low liquid volumes of volatile anesthetics, when applied locally to the skin enhanced the response to an electrical stimulus but higher volumes had no effect.
Skouteri
I
I
Department of Anesthesiology, Aretaieio Hospital, Medical School, University of Athens, 76 Vassilissis Sofia Ave, 11528 Athens, Greece.
Staikou
C
C
Sarantopoulos
C
C
Siafaka
I
I
Fassoulaki
A
A
D000279:Administration, Cutaneous; D000328:Adult; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004558:Electric Stimulation; D005260:Female; D006221:Halothane / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D007530:Isoflurane / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D008738:Methyl Ethers / Q000008:administration & dosage / Q000494:pharmacology*; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects*; D000077149:Sevoflurane
D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane; D007530:Isoflurane; D006221:Halothane