A minority of patients will react abnormally to propofol sedation. Before becoming properly sedated they lose affective control and have abnormal movements. Any anaesthetist could tell you about the occasional patient who, at propofol induction, becomes more and more agitated and restless, and who requires a surprisingly high dose before becoming comatose. This is called the propofol paradoxical excitement response. Chronic alcohol abuse has since long been suggested as a predisposing factor. A study in BJA tests this hypothesis.
190 patients undergoing knee surgery were divided into groups HD (harmfull drinkers) or NHD (non harmfull drinkers) based on a scoring system called AUDIT. (Alcohol Use Disorder Identification Test).
The study group was divided into two subgroups with two different propofol protocols.
In study 1 the propofol infusion rate was controllet to maintain a BIS of 70-80.
In study 2 a higher dose propofol infusion was compared to a lower dose.
The paradoxical excitement responses were graded
0 – none
1 – mild: increased talkativeness, irrational talking, or brief spontaneous movement with position remaining.
2 -moderate: restlessness, loss of cooperation, or spontaneous movements requiring repositioning with no need of restraint.
3 – severe: agitation and spontaneous movements with a need to restrain the patient.
If we are to believe this study, then there is indeed a dose-dependent correlation between alcohol abuse and paradoxical excitement response in patients sedated with propofol.
The authors (and other before them) suggest this has to to with genetic variations of the GABA-receptors. Both alcohol and propofol (and bensodiazepines) activate GABA-receptors, so that could be the common denominator. I can buy that.
‘Increase of paradoxical excitement response during propofol-induced sedation in hazardous and harmful alcohol drinkers.’
Jeong S, Lee HG, Kim WM, Jeong CW, Lee SH, Yoon MH, Choi JI.
Br J Anaesth. 2011 Dec;107(6):930-3. Epub 2011 Sep 7