European Journal of Anaesthesiology

Table of Contents - 2001 - Volume 18, Issue 07  


Original Article
(RD) Surgery

Blink duration as a measure of low-level anaesthetic sedation

A. K. Jandziol a1, M. Prabhu a1, R. H. S. Carpenter a2 and J. G. Jones a1c1
a1 University Department of Anaesthesia, Addenbrooke's Hospital, UK
a2 Physiological Laboratory, Downing Street, Cambridge, UK

Article author query
jandziol ak   [PubMed][Google Scholar] 
prabhu m   [PubMed][Google Scholar] 
carpenter rhs   [PubMed][Google Scholar] 
jones jg   [PubMed][Google Scholar] 

Abstract

Background and objective Variability in blink duration was examined to see whether it was sensitive to sevoflurane sedation at 0.05 and 0.1 minimum alveolar concentration (MAC).

Methods Blinks were measured with an infrared transducer in eight subjects. Sedation was scored using a visual analogue scale (VAS).

Results At baseline, 0.05 and 0.1 MAC sevoflurane, respectively, the overall median value of blink duration and its interquartile range were 95 (80–110) ms, 198 (163–245) ms and 210 (130–980) ms. The median percentage of blinks exceeding 500 ms was 0% (0–0.7%), 33.3% (25.5–34.7%) and 25% (15.7–63.3%) respectively. Values during 0.05 and 0.1 MAC sevoflurane were significantly different from baseline (P < 0.035) but not from each other. Baseline visual analogue scales showed large intersubject variability. Compared with baseline, VAS scores were higher at 0.05 MAC (P < 0.035) but not at 0.1 MAC. After discontinuing sevoflurane, median blink duration returned to baseline with a recovery half-life of 2.6 min (R2 = 0.95).

Conclusion Blink duration is a sensitive measure of sevoflurane sedation even at 0.05 MAC.

(Published Online August 16 2006)
(Accepted November 2000)


Key Words: anaesthetics; inhalational; sevoflurane; anaesthesia and analgesia; conscious sedation; anaesthesia recovery period; ocular physiology; blinking.

Correspondence:
c1 Correspondence: Prof. J. G. Jones.