Poisons and Poisoning - PowerPoint PPT Presentation

1 / 28
About This Presentation
Title:

Poisons and Poisoning

Description:

ECG, CXR. Specific blood levels. Management. Supportive ... Carful ECG monitoring is required. QRS interval is a guide to cardiac toxicity ( 100ms) ... – PowerPoint PPT presentation

Number of Views:163
Avg rating:3.0/5.0
Slides: 29
Provided by: drianwi
Category:
Tags: ecg | poisoning | poisons

less

Transcript and Presenter's Notes

Title: Poisons and Poisoning


1
Poisons and Poisoning
  • Dr Ian Wilkinson
  • Clinical Pharmacology Unit

2
Accidental?
3
Deliberate?
4
Suicides in the UK
  • 6,300 suicides pa
  • 20 of deaths in young people
  • 140,000 attempted suicides (parasuicides)
  • Most common 15-19 year old females
  • Most common method is poisoning
  • 50 paracetamol

5
(No Transcript)
6
General Comments
  • Try and get as much history as possible including
    witnesses
  • People truly wanting to commit suicide often lie
  • Remember the ABCs
  • Airway Clear mouth throat, gag reflex
  • Breathing O2 saturation, ABGs
  • Circulation Venous access, IV fluids if shocked
  • Assess GCS
  • Examination

7
History
  • When, what, how much ?
  • Why?
  • Circumstances
  • PMHx, Drug history
  • Psychiatric history
  • Assess mental status and capacity

8
Care with names!
  • Distalgesic
  • Anadin

9
Investigations
  • Always check blood glucose.
  • Send blood urine for toxicology screening.
  • ALWAYS measure paracetamol salicylate levels
  • Failure to diagnose treat is negligent.
  • UEs, LFTs, glucose, ABG, clotting, bicarbonate
  • ECG, CXR
  • Specific blood levels

10
Management
  • Supportive
  • Correct hypoxia, hypotension, dehydration, hypo-
    hyperthermia, and acidosis
  • Control seizures
  • Monitor
  • TPR, BP, ECG, Oxygenation, GCS
  • General
  • ? Absorption
  • ? Elimination
  • Specific antidotes

11
? Absorption
  • NEVER Ipecacuanha
  • Gastric lavage
  • Only if within 1 hour life-threatening amount
  • Never for corrosives
  • If ? LOC intubate
  • Activated charcoal
  • 50 g single or repeated dose (? elimination)
  • Doesnt bind heavy metals, ethanol, acids

12
? Elimination
  • Multiple dose activated charcoal
  • Quinine, phenobarbitone
  • Charcoal haemoperfusion
  • Barbiturates, theophylline
  • Diuresis
  • Urinary alkalinization
  • Dialysis

13
Paracetamol Overdose
  • Most common drug taken in overdose
  • Few symptoms or early signs
  • As little as 12g can be fatal
  • Hepatic and renal toxin
  • Centrolobular necrosis
  • More toxic if liver enzymes induced or reduced
    ability to conjugate toxin

14
Paracetamol Metabolism
15
Management
  • General measures including
  • UEs, LFTs, glucose, clotting ABG, bicarbonate,
    paracetamol and salicylate levels
  • Activated charcoal
  • lt8 hours
  • Take level after four hours
  • Start N-aceylcysteine if above treatment line
  • Patients are usually declared fit for discharge
    from medical care on completion of its
    administration. However, check INR, creatinine
    and ALT before discharge. Patients should be
    advised to return to hospital if vomiting or
    abdominal pain develop or recur

16
Management 2
  • gt8 hours
  • Urgent action required because the efficacy of
    NAC declines progressively from 8 hours after the
    overdose
  • Therefore, if gt 150mg/kg or gt 12g (whichever is
    the smaller) has been ingested, start NAC
    immediately, without waiting for the result of
    the plasma paracetamol concentration
  • gt24 hours
  • Still benefit from starting NAC

17
Treatment Graph
18
N-acetylcysteine
  • Supplies glutathione
  • Dosage for NAC infusion - ADULT
  • (1) 150mg/kg IV infusion in 200ml 5 dextrose
    over 15 minutes, then
  • (2) 50mg/kg IV infusion in 500ml 5 dextrose over
    4 hours, then
  • (3) 100mg/kg IV infusion in 1000ml 5 dextrose
    over 16 hours
  • Side-effects
  • Flushing, hypotension, wheezing, anaphylactoid
    reaction
  • Alternative is methionine PO (lt12 hours)

19
Aspirin Overdose
  • Early features
  • hyperventilation, sweating, tremor, tinnitus,
    nausea / vomiting, or hyperpyrexia
  • Metabolic features
  • Hypo- or hyper-glycaemia, hypokalaemia,
    respiratory alkalosis, metabolic acidosis
  • Others
  • renal failure, pulmonary oedema, seizures, coma,
    death

20
Management
  • General measures
  • Bloods
  • Salicylate (paracetamol) level gt2 hours, and
    after 2hrs
  • gt700 potentially lethal
  • gt500 moderate-severe poisoning
  • UEs, glucose, ABG, bicarbonate
  • Activated charcoal
  • Rehydrate, monitor glucose, correct acidosis and
    K
  • If levels gt500mg/L alkalanize urine (HCO3-)
  • Levels gt 700 mg/L before rehydration, renal
    failure or pulmonary oedema consider
    haemodialysis

21
TCAs -Introduction
  • Potentially fatal (2.5 to 3.5g of amitriptyline)
  • Neurological and cardiac problems common
  • Toxicity due to anticholinergic actions, and
    direct quinidine-like effect on the myocardium
  • Serious toxicity results from-
  • Ventricular dysrhythmias
  • Seizures
  • Hypotension
  • Respiratory depression
  • Initial symptoms at presentation may be trivial,
    and most major problems occur within 6hrs

22
TCAs-Features of poisoning
  • Peripheral
  • Sinus tachycardia, hot dry skin, dry mouth,
    urinary retention, hypotension and hypothermia
    may occur
  • CNS
  • Dilated pupils, ataxia, nystagmus, squint, ?LOC,
    coma, seizures, respiratory depression, ?tone, ?
    ?reflexes, ? plantars
  • ECG
  • prolonged PR and QRS interval, ? QT
  • ventricular dysrhythmias

23
TCAs -Management
  • GCS and QRS, best indicators of toxicity
  • Supportive
  • do not use flumazenil if benzo taken
  • Check airway, maintain ventilation, correct
    hypoxia
  • Check ABG, if ? CO2 requires ventilation
  • Correct hypotension (crystalloids)
  • Gastric lavage if within 1 hr, and activated
    charcoal
  • Rx fits and agitation with diazepam
  • Rewarm slowly if hypothermic
  • Close monitoring for 24hrs

24
TCAs- Dysrhythmias
  • Carful ECG monitoring is required
  • QRS interval is a guide to cardiac toxicity
    (gt100ms)
  • Avoid antidysrhythmic drugs. They may make
    matters worse
  • Correct hypoxia and acidosis. Aim for a pH of
    7.45-7.50 (no higher)
  • use iv boluses of sodium bicarbonate
  • Sodium loading may also help
  • Prolonged CPR may be of use

25
Tricyclic OD Initial ECG
26
Tricyclic OD Recovery ECG
27
Benzodiazepine Overdose
  • Deaths from poisoning with benzodiazepines alone
    are rare, but may be lethal in combination with
    other CNS depressants
  • Treatment is supportive and aimed at maintaining
    adequate ventilation whilst supporting
    cardiovascular depression
  • Flumazenil (specific benzodiazepine antidote) is
    not licensed (in the UK) for routine use in
    benzodiazepine overdoses
  • Flumazenil may induce seizures particularly
    dangerous where tricyclic antidepressants have
    been taken
  • Flumazenil, may however, be used in the
    differential diagnosis of unclear cases of
    multiple overdoses but expert advice is ESSENTIAL.

28
Other agents
  • Opiates Naloxone
  • Iron Desferrioxamine
  • Lead Sodium EDTA
  • Digoxin FAB
  • Calcium blockers Calcium
  • Ethylene glycol Ethanol
  • Lithium Dialysis
Write a Comment
User Comments (0)
About PowerShow.com