Analgesia During Propofol Sedation: Ketamine Is Safer Than Fentanyl
Use of ketamine as an adjunct analgesic agent was associated with
fewer
adverse events, especially desaturation.



Propofol is a rapid-acting, potent sedative that has gained
popularity as
an agent for procedural sedation and analgesia (PSA) in the emergency

department, especially for deep sedation. Because propofol is not an
analgesic, additional medication is often indicated for pain, but
opioids,
such as fentanyl, can increase the risk for respiratory depression.
Ketamine causes minimal respiratory depression and, at doses lower
than
those used for sedation, has analgesic effects. These authors
compared
adverse events during propofol sedation when fentanyl or ketamine was
used
for analgesia.

Sixty-three patients (age range, 14-65 years) with painful conditions

requiring PSA were randomized to receive either intravenous ketamine
(0.3
mg/kg) or fentanyl (1.5 {micro}g/kg). All patients were monitored
with
pulse oximetry and capnography. After 2 minutes, all patients
received 0.4
mg/kg of IV propofol; additional 0.1 mg/kg doses were given until
sedation
was achieved. A panel of emergency physicians and anesthesiologists
developed a scale for categorizing the severity of events (e.g.,
desaturation, dysrhythmias) and interventions (e.g., assisted
ventilation,
naloxone administration) that occurred during sedation. The group of
patients who received fentanyl had a significantly higher incidence
of
moderate events (35% vs. 22%) and severe events (16% vs. 0%) than did
those
who received ketamine. One patient who received fentanyl required
bag-valve-mask-assisted ventilation. No patient required an
artificial
airway. Efficacy of sedation was similar in the two groups.

Comment: This study's findings suggest that ketamine administered in
analgesic doses is safer than fentanyl is during sedation with
propofol,
but both agents appear to be relatively safe. When performing deep
sedation, particularly with multiple agents, providers must be
prepared to
provide assisted ventilation for a brief period.

-- Diane M. Birnbaumer, MD, FACEP

Published in Journal Watch Emergency Medicine December 24, 2008
Citation(s):

Messenger DW et al. Subdissociative-dose ketamine versus fentanyl for

analgesia during propofol procedural sedation: A randomized clinical
trial.
Acad Emerg Med 2008 Oct; 15:877.