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A
randomised partially blinded controlled trial comparing operator
administered midazolam with Patient Maintained Sedation with propofol
for wisdom tooth extraction. Anderson
KJ1, Leitch J2, Gambhir S1, Millar K3
and Kenny GNC1 Departments
of Anaesthesia1, Dental Surgery2 and
Psychological Medicine3, University of Glasgow. Introduction:
Traditionally sedation for dental surgery has been obtained by
operator sedation with incremental midazolam (OSM). However, concern
over the safety of this technique has arisen from reports of
significant arterial oxygen desaturation, and audits of the safety of
gastroscopy. Recently our group has shown that patient maintained
sedation with propofol (PMSp) was effective for dental surgery1.
The objective of this study was to compare the safety, efficacy and
operator satisfaction of PMSp with OSM. Methods:
110 prospective patients (89 female) presenting for wisdom tooth
extraction were enrolled, and randomised to receive PMSp or OSM (55
each). For OSM midazolam was administered in 1mg increments, every
minute, until the patient expressed readiness for the LA injections.
For PMSp, the system was commenced at a target plasma concentration (CpT)
of 1.5 mcg/ml until the effect site concentration (Ce) was 1mcg/ml,
then the CpT was set to 1mcg/ml. At this point the patient
was given a button to press. If they double pressed within 1 second,
the CpT would increase by 0.2mcg/ml. The lockout time was
set to 2 minutes. If they didn’t press for 6 minutes the system
would reduce the CpT by 0.2 mcg/ml. The system was set to
deliver a maximum CpT of 3.0 mcg/ml. Measurements prior to
and after sedation: anxiety by VAS, symbol digit substitution score
(cognitive function), word and pictures for memory tests. A 30 second
video clip for blinded behavioural analysis by psychologists was taken
before seadtion, during LA injection, during tooth extraction and on
exit from procedure room. Physiological safety data (HR, BP and SpO2),
and CpT and Ce for the propofol groups were recorded at
5-minute intervals, and also minimum SpO2, min/max BP and HR for the
whole procedure were also recorded. A blinded recovery nurse assessed
patients as ready for discharge. Results:
Both groups were comparable with respect to age, sex, ease and
duration of procedure, trait anxiety score, baseline anxiety VAS and
all baseline physiological measurements. Mean (SD) midazolam dose was
6.7 (1.7) mg. Mean (SD) calculated propofol plasma concentration (Cp)
was 1.4 (0.5) when ready for LA injection, and the maximum Cp
throughout the procedure was 1.9 (0.5). Mean (SD) Ce was 1.3 (0.4)
when ready for LA, and maximum Ce was 1.7 (0.5). Tabulated
results are expressed as mean (SD), except drop in SpO2, which is mean
(range).
There
was no difference between groups with respect to patient satisfaction;
this was high for both groups. Discussion:
PMSp was associated with a greater anxiolytic effect, less depression
of cognitive function, less arterial oxygen desaturation and quicker
discharge. OSM was associated with superior amnesic effects early in
the procedure but not at extraction. Neither agent caused retrograde
amnesia. References: 1. Leitch et Al. Patient-maintained sedation for oral surgery using a target-controlled infusion of propofol – a pilot study. British Dental Journal 2002, 193:(accepted). |
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