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

39

Risk Assessment

• Requires a bit of knowledge

• Substance

• Toxicokinetics (not pharmacokinetics)

• Amount

• Interaction between multiple co-ingestants

39

40

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 40

41

Centre antipoison du Québec

Service téléphonique sans frais24 heures sur 24, 7 jours sur 7

1 800 463-5060

42

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! 42