Risk Assessment in
Acute Poisoning
Dre Sophie Gosselin
Internal Medicine Academic Rounds
March 16th, 2010
Acknowledgement
• Dr Lindsay Murray
• former Australian Poison Control Director
• Author of “Toxicology Handbook”
Goal
Change the way you approach the
poisoned patient
At the end of this presentation you will …
• No longer write “drug overdose” or “polypharmacy overdose” as
a diagnosis
• Construct an individualised risk assessment for each poisoned
patient
• Use the risk assessment to plan all subsequent management
Background
• Acute poisoning is a common emergency presentation
– Most large EDs in urban areas see 150-400 acute poisoning
presentations / 100,000 population / year
• Context is usually
– Deliberate self-poisoning in adolescents and adults
– Complications of recreational drug abuse
– Accidental paediatric exposures
Background
• The presentation to hospital should be regarded as an
acute medical exacerbation of a chronic psychosocial
disorder
• Underlines the importance of psychosocial assessment
and follow-up as an integral part of care
Question
What is the in-hospital mortality from acute poisoning?
A. 5%
B. 1%
C. 0.5%
D. 0.1%
What is the cause of death in these cases?
Characteristics of acute poisoning
• Acute mortality is usually related to cardiovascular,
neurological and respiratory complications
• Patients are
– young and have few medical co-morbidities
– older with chronic diseases and co-morbidities.
• Discrete, dynamic and sometimes time-critical illness
• The clinical course is frequently predictable
Attention to the principles of critical care,
support of the body’s own mechanisms
ensures the survival of the vast majority of
patients, rather than complex manoeuvres such as GI
decontamination, enhanced elimination or antidotes
General approach to Management of Poisoning
• Resuscitation
• Risk assessment
• Supportive care and disposition
• Decontamination
• Investigations
• Enhanced elimination
• Antidotes
• Disposition
Resuscitation
• Airway
• Breathing
• Circulation
• Detect and correct
– Seizures
– Hypoglycemia
– Hyper-/hypothermia
• Emergency antidotes
Risk Assessment
• Should be formulated as soon as possible
• Second priority after resuscitation.
• A distinct quantitative cognitive step through which
the clinician attempts to predict the likely clinical
course and potential complications for the individual
patient at that particular presentation
Risk Assessment
• Allows informed decisions regarding all subsequent
aspects of management for that particular presentation
• In approximately the majority of cases it reassures the
clinician that basic supportive care will be sufficient
• In selected cases it allows early prioritization of specific
interventions in a proactive manner
Risk Assessment
Risk = Hazard x Exposure
Risk Assessment
Takes into account
1. Agent(s)
2. Dose(s)
3. Time of ingestion
4. Clinical features and progress
5. Patient factors (e.g. age,weight, comorbidities)
Risk Assessment
“The history of ingestion is frequently unreliable”
TRUE or FALSE?
• When altered mental status prevents an accurate history
– Tablet counts
– Collateral history from family and friends
– Evidence brought to ED by ambulance personnel
– Correlation of clinical status with toxico-epidemiologic trends
Risk assessment in children
• Dose-response expressed in mg/kg (load) is usually
the same as for adults
• Children rarely ingest more than 2-3 tablets, which is
often an order of magnitude less than the dose ingested
by adolescents and adults in deliberate self-poisoning
• Exact dose and time may be difficult to estimate but an
interval range can often be found.
Risk assessment
• ‘Worst case scenario’
• Assume the time of ingestion is the latest possible.
• Assume all missing tablets have been ingested
• Do not attempt to account for spillage
• If more than one patient is involved, assume each
could have consumed all the missing tablets
Risk assessment
• Consider non-accidental injury• Unusually severe intoxications that suggest very
large or repeated doses
• Poisoning in a child that is not yet crawling (< 10
months)
• Poisoning in individual with disabilities or
decreased mobility
Case One - Acetaminophen
• 33-year-old female, previously well, 2 months partum
• Awoke complaining of abdominal pains 0530 hrs Saturday
• Transported to a Hospital by ambulance
• Gave history of ingesting 8g acetaminophen for headaches over a 4
hour period the previous day
• Seen by resident : Vital signs unremarkable, abdominal examination
- mild epigastric discomfort
• PD: ?gastritis, ? Gallstones
• LFTs AST 261, Alt 329
RISK
ASSESSMENT?
Risk Assessment - Acute Acetaminophen
Ingestion
• Threshold dose for hepatotoxicity (not death) is variable
but generally quoted as 150 mg/kg
• Risk assessment refined by a single timed
acetaminophen level plotted on Rumack-Matthew
nomogram between 16 and 20 hours
• What about
– Unknown time
– Late presentation
– Staggered ingestions
– Repeated supratherapeutic ingestion
Acetaminophen case - Progress (1)
• Settled (partially) with symptomatic care
• Abnormal LFTs discussed with resident who told her the
acetaminophen dose was too low to cause problems
and that probably represented cholecystitis
• Discharged home with instructions to see GP in one
week
• Letter to GP noted abnormal LFTs, suggested they might
be due to acetaminophen use and asked for him to
repeat them in one week.
Acetaminophen Case Progress (2)
• Remained unwell
• Consulted clinic later that day - ordered repeat LFTs outpatient
• Sunday 0420 collapse with vomiting, abdominal pain
• Ambulance called 0430: P 100, RR 52, “hyperventilation, recently
discharged with acetaminophen poisoning”: applied disconnected
oxygen mask and did not transport
• Ambulance recalled 0900: P 120, RR 44 to hospital:
• Triage category 3, 3 1/2 hour to see doctor
• Medical assessment
– Extemely unwell, tachycardic, tachynpnoeic, confused
– pH 6.3, pCO2 9, ALT 4987, AST 9722, INR 7, APAP 240 mcmol/L
Acetaminophen Case - Progress (3)
• Transferred to ICU/Liver Unit
• Listed for hepatic transplantation
• Died fulminant hepatic failure following Friday in liver
unit
• Autopsy showed hepatic injury characteristic of
acetaminophen poisoning
Acetaminophen Case - Enquiry
• Cause of death
• Third party involvement
• Care and treatment at hospital
• Care and treatment by GP
• Care and treatment by ambulance
• How much acetaminophen consumed
• Time of ingestion
• Intention of ingestion (?self-harm)
• Did standard of care effect chances of survival
Acetaminophen Case
• Died of Acetaminophen hepatotoxicity
• Failed risk assessment
• Number of possibilities as to dose, time of ingestion and
intention
• Failure to recognise sick patient by ambulance and
triage
• Death probably unavoidable at second presentation
Case Two: Bupropion,
• 32-year-old male, recent relationship breakdown
• Rang father 0015 stating he had just OD’ed on 98
bupropion 150 mg XR and some anti-inflammatory
tablets
• Brother arrived and took him to tertiary hospital ED
• Triaged “Category 3” at 0100
• P 127, BP 120/40, RR 18, GCS 15
RISK
ASSESSMENT?
Risk Assessment - Bupropion
• Any dose
– Seizures, tachycardia, tremors, agitation, altered mental status
progressive over 6-12 hours
– First seizure usually occurs 6-12 hours after ingestion
• >4.5g
– Seizures universal and may occur earlier
• >9g
– Severe cardiotoxicity, haemodynamic instability, QRS and QT
prolongation and cardiac deaths reported
– Fatal without aggressive supportive care
Bupropion Case - Progress (1)
• RN called PIC: serious OD, seizures likely, consider
WBI
• MD read Uptodate and decided to proceed with WBI
• Failed NG placement
• NG finally inserted 0240 by which time P 140, GCS 10
Bupropion Case - Progress (2)
• Seizures 0245, 0305
• ECG 0310: sinus tachy, widened QRS
• RSI intubation 0338,
• ?SVT then asystolic arrest at 0410
• Post-mortem
– 8x 6 x 5cm pharmacobezoar in stomach
– toxicology: bupropion 0.54 mg/L, diflusinal 265 mg/L
Bupropion Case-M&M + Coroner’s
• Actual cause of death
• Should activated charcoal have been given to the deceased in an
effort to prevent or limit the further absorption of toxic material?
• Was the administration of WBI delivered in a timely manner?
• Should the possibility of an overdose of a substance other than
merely bupropion have been recognised, and if so whether it should
have dictated a different course of action?
• Was sufficient consideration given to the delivery of life supportive
measures, such as the maintaining of the deceased’s airway and
monitoring for signs of toxicity?
• In the event, did anything that was done or that was omitted to be
done contribute to the fatal outcome?
Recommendations
• Clarify, for the benefit of clinical staff in emergency
settings, the appropriateness or otherwise of
administering activated charcoal in respect of slow
release drug overdoses in general and of buproprion
overdoses in particular
• Read the latest guidelines from EAPCC and NACCT?
• Read Clinical Toxicology Journal’s regularly?
Recommendations
• Encourage doctors in emergency settings to
personally utilise the services of PICs, such as the
telephone services provided by specialist clinical
toxicologists, as a source of information relative to
the treatment of drug overdoses
• Discourage the practice of doctors delegating to
nursing staff the responsibility of communicating
with Poison Control Centers
Recommendations
• Instruct clinical staff responsible for triage to accord to drug
overdose presentations triage category 1 or 2 to in order to
minimise delay
• Ensure that appropriate decontaminants are always made
immediately available within an emergency department
• Ensure that in drug overdose presentations a thorough
enquiry is made of all presenting patients as to the number,
quantity and identity of all substances ingested, and
ensuring that the fact of and result of all such enquires are
adequately noted
Risk Assessment
• Requires a bit of knowledge
• Substance
• Toxicokinetics (not pharmacokinetics)
• Amount
• Interaction between multiple co-ingestants
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Poison Control Centre
• Specialised clinicians (Rn or Pharm) in clinical
toxicology
• Back up with clinical toxicologist physicians.
• Assist with
– risk assessment
– substance identification and database research
– specialised laboratory testing
– on going management
– follow patients when transferred
– offer expertise
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Centre antipoison du Québec
Service téléphonique sans frais
24 heures sur 24, 7 jours sur 7
1 800 463-5060
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Conclusions
• Proper history and detective work make substrates for a
good risk assessment
• Good risk assessment help patient care
• Toxicokinetics doesn’t equal pharmacokinetics
• Poison Control exist
• Value of advice depends on value of information given
• MD in charge should call not delegate.
• They are your best friend in case of intoxications
• Call them!
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