The problem with opiate reversal is that it is often performed by junior
staff whose aim is to get the patient 'back to normal'. However most
opiate overdoses occur concommitantly with alcohol and benzodiazepines so
even when the patient wakes up they are often still spaced from other
substances. The aim should be to return the patient to normal spontaneous
ventilation with good tidal flows and not just a decent repsiratory rate.
This can be achieved with small doses of naloxone or infusion.
We are all concerned in case the agitated chap who we wake up will go off
and collapse later when the naloxone wears off. There is little evidence
that this in fact happens. Indeed one study showed that none of 317
patients who were reversed by paramedics and who refused further treatement
were found dead within 12 hours of administration of naloxone [1].
Allowing patients to wake up slowly means you have the opportunity to
ensure they are informed about risk modification and also inform them about
the availability of local services. If they wake up after a few hours and
want to leave then it is less likely that you are dealing with a methadone
overdose. You are also less likely to encounter acute withdrawl and the
risks that perhaps vomiting can bring on top of co-ingestion of alcohol.
But remember that scary paper from 1996 BMJ lesson of the week of the chap
who was found dead on the ward after release from ITU when naloxone
infusion was stopped ? [2]
I think it was Greg Henry who said 'I never wake up anyone I dont like' !
John Ryan
[1] Prehosp Emerg Care 1999 Jul-Sep;3(3):183-6
Are heroin overdose deaths related to patient release after prehospital
treatment
with naloxone?
Vilke GM, Buchanan J, Dunford JV, Chan TC.
Department of Emergency Medicine, University of California, San Diego
Medical
Center, 92103, USA. [log in to unmask]
OBJECTIVE: Naloxone is frequently used by prehospital care providers to
treat
suspected heroin and opioid overdoses. The authors' EMS system has operated
a policy of allowing these patients, once successfully treated, to sign out
against medical advice (AMA) in the field. This study was performed to
evaluate
the safety of this practice. METHODS: The authors retrospectively reviewed
all
1996 San Diego County Medical Examiner's (ME's) cases in which opioid
overdoses
contributed to the cause of death. The records of all patients who were
found
dead in public or private residences or died in emergency departments of
reasons
other than natural causes or progression of disease, are forwarded to the
ME
office. ME cases associated with opiate use as a cause of death were
cross-compared
with all patients who received naloxone by field paramedics and then
refused
transport. The charts were reviewed by dates, times, age, sex, location,
and,
when available, ethnicity. RESULTS: There were 117 ME cases of opiate
overdose
deaths and 317 prehospital patients who received naloxone and refused
further
treatment. When compared by age, time, date, sex, location, and ethnicity,
there
was no case in which a patient was treated by paramedics with naloxone
within
12 hours of being found dead of an opiate overdose. CONCLUSIONS: Giving
naloxone
to heroin overdoses in the field and then allowing the patients to sign out
AMA resulted in no death in the one-year period studied. This study did not
evaluate for return visits by paramedics nor whether patients were later
taken
to hospitals by private vehicles.
[2] BMJ 1996;313:481-482 (24 August)
http://bmj.com/cgi/content/full/313/7055/481?view=full&pmid=8776322
Education and debate
Lesson of the Week: Fatal methadone overdose
T J Hendra, consultant physician,a S P Gerrish, consultant anaesthetist,a A
R W Forrest, consultant chemical pathologist a
a Directorate of Medicine, Intensive Care Unit and Department of Clinical
Chemistry,
Royal Hallamshire Hospital, Sheffield S10 2JF
Correspondence to: Dr T J Hendra, Department of Geriatric Medicine, Royal
Hallamshire
Hospital, Sheffield S10 2JF.
Methadone is a synthetic opioid with potent analgesic effects often used
for
the detoxification or maintenance of an opiate addict. It differs from
morphine
in that it has an exceptionally prolonged duration of action with a half
life
averaging 25 hours, although durations of up to 52 hours have been reported
during long term maintenance treatment.1 The variation in metabolism may be
responsible for the irregular and unpredictable clinical course of patients
who have taken overdoses of this agent.
Methadone
overdose can
follow an
unpredictable
course in non-
tolerant patients,
who are at risk of
sudden death
Case report
A 22 year old man presented to the accident and emergency department at
1400
hours having taken an overdose of 420 mg of methadone three hours earlier;
he
had obtained the drug illicitly. He was a known drug misuser who had
epilepsy,
treated with sodium valproate. He had been treated before for depression
with
amitriptyline and fluoxetine. A heavy cigarette smoker with a high alcohol
intake,
he had taken four overdoses within the past two months.
On arrival he was drowsy and refused to submit to regular nursing
observations.
On leaving the hospital, he collapsed on the pavement while smoking a
cigarette.
After being brought back into the department, unconscious and unresponsive
to
pain, he was given three 0.4 mg boluses of intravenous naloxone and 0.4 mg
flumazenil,
with a prompt improvement in his level of consciousness. He was transferred
to the admissions ward, where he cooperated poorly with monitoring by the
nursing
staff and hindered the use of a pulse oximeter by frequently getting out of
bed and wandering out of the ward. At 1830 hours he had an episode of
altered
consciousness and responded to 0.4 mg naloxone within two minutes. At 2130
hours
a naloxone infusion of 0.3 mg/hour was started following another episode of
unconsciousness associated with an oximeter oxygen saturation of 22%.
He was transferred to the intensive care unit, where he remained
haemodynamically
stable but had a fluctuating level of consciousness, varying from wide
awake
to rousable on request. The naloxone infusion of 0.3 mg/hour was continued,
and a bolus injection of 0.2 mg given at 2345 hours greatly improved his
level
of consciousness. Blood was taken for toxicological analysis and oxygen
administered
via a face mask.
The following morning the naloxone infusion was temporarily stopped to
assess
whether it was still required and he got up to smoke a cigarette under
nursing
supervision. After he became sleepy, but was still rousable and able to
communicate,
the naloxone infusion was restarted at a rate of 0.2 mg/hour with good
effect.
He was seen by the on call psychiatric team and a decision was made to
discharge
him back to the general medical ward if stable. Before leaving the
intensive
care unit at 1800 hours the serum toxicology results were reported as
methadone
353 ?g/l, temazepam <50 ?g/l, desipramine <50 ?g/l, diazepam 813 ?g/l, and
nordiazepam
990 ?g/l. The therapeutic ranges given were up to 250 ?g/l for diazepam and
up to 1000 ?g/l for methadone. The laboratory also commented that while
serum
methadone concentrations of up to 1000 ?g/l were found in patients
receiving
methadone maintenance treatment, death following overdose might be
associated
with a concentration as low as 200 ?g/l in blood. He was transferred awake
and
alert to a general medical ward with instructions for the naloxone infusion
to finish later that evening.
On the medical ward he was mobile and talking to the nursing staff until
0200
hours, when he had a cup of hot chocolate before retiring to bed. He was
not
being monitored by an oximeter at this time. The naloxone infusion was slow
to complete, eventually finishing at 0330. He was observed to be sleeping
and
breathing satisfactorily at 0400 but was found dead in bed at 0655.
At necropsy there were no clinically relevant physical findings: his
methadone
concentration was 822 ?g/l in femoral blood and 7 ?g/l in stomach contents.
Diazepam and nordiazepam blood concentrations were 103 ?g/l and 165 ?g/l,
respectively.
The pathologist's opinion of the cause of death was methadone overdose.
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