Effects of a low concentration of isoflurane on contrast sensitivity in volunteers

Abstract

The effects of 0.15% quasi steady-state end-tidal isoflurane on the contrast sensitivity of five healthy volunteers were investigated by measuring their performance in computer generated letter discrimination tasks. A series of letters were displayed on a computer screen so that the luminance of the letter differed from that of the background. Two protocols were used: in the static protocol, the letter remained displayed on the screen until the subject responded, whereas in the dynamic protocol, the letter was displayed for 1/72 s only. Isoflurane significantly decreased contrast sensitivity in both protocols in all subjects.

Effects of low‐dose isoflurane on saccadic eye movement generation

“…The subjects wore a nose clip and the end-tidal anaesthetic concentration was measured using a Datex Capnomac Ultima. The instrument was calibrated using a gas chromatograph and six gravimetrically prepared primary standards spanning the range 0.06-0.79% isoflurane as described previously [7]. An attempt was made to double-blind the study.…”

Subhypnotic Doses of Isoflurane Impair Auditory Discrimination in Rats

“…In addition to the aforementioned studies on ketamine, nitrous oxide, and benzodiazepines, there are two studies on humans that investigated the effect of low doses of isoflurane on performance in visual sensory tasks. In one study, isoflurane at 0.15% significantly decreased contrast sensitivity, 33 whereas in a second study, the effects of 0.4% isoflurane on accuracy in a visual search task were inconclusive, although reaction times were significantly increased. 34 There are several studies that have investigated the effects of subhypnotic doses of anesthetic agents on language processing, but these studies were concerned primarily with memory for words presented during the drug condition rather than word recognition per se.…”

The effect of low dose sevoflurane on saccadic eye movement latency

“…The oxygen or oxygen/sevoflurane mixture was delivered to the subject using a Bain system and physiological mouthpiece, with the nose occluded. End‐tidal carbon dioxide (F E ′CO 2 ) and sevoflurane (F E ′Sev) were measured using a Datex Capnomac Ultima, which had been calibrated using manufacturers' known gas samples and compared with gravimetrically prepared primary standards previously described [11]. F E ′CO 2 was maintained at 4.5–5 KPa and F E ′Sev was equilibrated without over pressure to 0.15%.…”