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ANALGESIA WITHOUT SEDATIVES DURING COLONOSCOPIES: WORTH CONSIDERING?
5
Moderate sedation
is as a drug induced reduction of cognitive function. Patients could
purposefully respond to verbal commands after light tactile stimulation. Respiration is
not impaired.
18
Drugs most commonly used for moderate sedation are midazolam (47%),
spasmolytics (11%), and other drugs (5%), mostly combined with an analgesic, e.g. opioids
(33%).
24
A combination of two or more analgo-sedatives was used in 37% of the performed
procedures. This combination provides excellent analgo-sedation during colonoscopy, but
increases the risk for more deep sedation and more frequent respiratory depressions.
The duration of action of these combinations might last longer than the procedure, resulting
in a delayed recovery and discharge from hospital, disrupting normal everyday activities of
the patients and actually increasing treatment costs.
THE IDEAL AGENT
The properties of an ideal analgesic agent for colonoscopy aim at a comfortable yet alert
patient and facilitate a rapid turnover of patients. The ideal sedation drug also implies a
superior safety profile, analgesic and optionally anxiolytic effects combined with a fast
begin and termination of action, the possibility to titrate to a planned sedation level, a fast
recovery, and all of this without the necessity for extra personnel.
Following Moerman`s hypothesis “If pain relief is adequate, sedation is no longer being
required.”
25
, the question arises whether analgo-sedation could be achieved by using
analgesics only. Various studies on sedation regimens have been published, but only a few
concentrated on analgesic agents solely.
26-28
Meperidine
Meperidine is a synthetic analgesic with an onset of effect within 10 to 15 minutes, lasting
for 2 hours with a plasma half-life of 3 to 4 hours. Metabolism to normeperidine occurs
rapidly. Normeperidine follows a renal excretion with an extended elimination half-life of
17 hours. This pharmacokinetic profile strongly argues against the use of meperidine for
relatively short procedures like colonoscopies.
29
Fentanyl
Fentanyl is an opioid, which has a faster recovery profile than meperidine. Onset of action
is within 1–2 min, peak effect occurs at 3–5 min, and duration of action ranges between
30–60 min.
For colonoscopies, fentanyl is mostly used in a combination with propofol or a
benzodiazepine. Only Lazaraki et al.
26
evaluated the efficacy and safety of fentanyl alone
(< 0.5 µg/kg, mean 36 µg) in comparison with midazolam (2 mg, mean 4.6 mg). Fentanyl
providedmore rapid recovery thanmidazolamcombinedwith a lower mean discomfort (0.4