Home | | Medicine Study Notes | Poisoning and Overdose - Emergency Management

Chapter: Medicine Study Notes : Emergency Management

Poisoning and Overdose - Emergency Management

Cause of significant proportion of arrests in 18 – 35 year olds.

Poisoning and Overdose


·        Cause of significant proportion of arrests in 18 – 35 year olds

·        Duration of arrest and dose of toxin determinants of survival

·        Do general management

·        Manifestations of poisoning:

o   Exaggerated therapeutic response (eg sedation with BZD)

o   Pharmacological effects (eg respiratory depression, convulsions)

o   Accidental: children, single poison

o   Intentional: adult, often multiple, taken in conjunction with alcohol

·        Management:

o   History: 

§  Find out the drug if you can (has someone brought in the packet?): but only a few will change management (paracetamol, salicylates, lithium, paraquat, quinine, phenobarbitone, iron salts)

§  Very unreliable – especially the number of tablets taken

o   Supportive treatment:

§  A,B,C: Respiratory depression is the most common cause of death. 

§  Maintain airway, check blood gases. Check for hypotension (®raise legs except in heart failure, volume expanders). Monitor electrolytes 

§  Maintain safety: close supervision, no access to drugs on ward, etc 

o   Intensive support treatment: IV fluids, ?NG tube, maintain vital functions, nursing care (eg suction, pressure sores, limb movement ® ¯thrombosis) 

o   Treat complications: hypothermia, hyperthermia (salicylates and stimulants sponge down, use fan), seizures (iv diazepam), arrhythmias (leave bradycardia, tachycardia – correct acidosis, try amiodarone), hypoglycaemia (salicylates, oral hypoglycaemics) 

o   Plus treatment specific to poison

o   Mental health assessment

·        Investigations: 

o   Blood levels: sometimes useful (eg Li, aspirin, theophylline, carbamazepine). Waste of time for TCAs 

o   Urine Screen: Rarely changes management, no quantitative information, really only for criminal cases (eg after MVA)

·        Corrosives:

o   Never induce vomiting

o   Drink copious fluids

o   Soak eyes, skin, mucous membranes

o   Petroleum: beware of inhalation, cup of milk


·        Eliminating poisons. If sure it‟s not petroleum products, caustics, corrosives or acids, then options may include:

o   Activated charcoal

§  Better than emesis 

§  Charcoal powder, mixed with H2O: needs to be within 60 minutes. Give SINGLE 50 g dose in an adult (1 g/kg) 

§  Reduces GI absorption of paracetamol, aspirin, phenytoin, digoxin, TCAs, theophylline, carbamazepine.

§  Don‟t use for volatile hydrocarbons or corrosives or an unprotected airway

§  Good for unionised drugs. Does not bind with acids, alkalis, alcohols, lithium.

§  Generally safe but constipation, aspiration may be problems (protect airway)

o   Multiple doses only for drugs undergoing enterohepatic circulation or diffusing into the gut Þ drugs with a small Vd, low clearance, low protein binding and long T½. Eg Theophylline, carbamazepine, quinine, phenobarbitone. NOT Paracetamol.


·        PH adjusted diuresis:

o   Alkaline diuresis: aspirin, phenobarbitone

o   Acid diuresis: amphetamine, methadone.  Doubtful use and dangerous


·        Dialysis: Haemodialysis. Only useful if low Vd, small molecule and low protein binding (eg lithium, theophylline, salicylates, alcohol and barbiturates)


·        Whole bowel irrigation: „Go Lightly‟ – Xray prep

·        Questionable effectiveness:


o   Emesis: Not effective? Ipecac – never if airway reflexes not intact. Causes emesis in 90% within 15 – 30 minutes


o   Gastric lavage: large bore catheter through mouth. 1ml/kg of body temperature water, recover, repeat. Little evidence of benefit and ­ risk of aspiration. Contraindicated if acid, alkali, or petroleum


Common poisons


·        Paracetamol

o  Walk in, conscious

o  RUQ pain


o  Conjugation pathway easily saturated. Of the remainder, 15% is metabolised to a metabolite that combines with glutathione. If glutathione is depleted, metabolite causes hepatic damage


o  Toxic dose 140 mg/kg (textbook), 200 mg/kg (Starship), lower if chronic alcoholism, enzyme inducing drugs or fasting


o  Measure plasma concentration. Treat if > 200 mg/ml, 100 if liver disease, anorexia, etc. Threshold declines for each hour after ingestion


o  Absorbed quickly so gastric lavage or activated charcoal only effective within 45 minutes


o  N-acetylcysteine (NAC) best antidote – saturates alternative pathway so all the paracetamol is metabolised through the main pathway. Normal dose is 10 - 15 mg/kg per 4 hours acutely, per 6 hours at home


o  Monitor AST/ALT, PT (INR)

·        TCAs: see Topic: Tricyclic Antidepressants

·        MAOIs: see Topic: MAOIs (Monoamine Oxidase Inhibitors)

·        Opioids: 

o  Marked sedation, pinpoint pupils, ¯¯ respiration (differential: stroke)

o  Naloxone (but short T½ ® will lapse back) 

·        Stimulants (cocaine type drugs): ­BP, tachycardia, arrhythmia, dilated pupils [sympathetic effects], seizures 

·        Barbiturates ® flumazenil (can cause seizures – so not if SSRIs/TCAs/antihistamines as well – which also cause seizures) 

·        Dibenzazepine antidepressants: Rapidly absorbed, high Vd, protein bound. Look for myocardial toxicity, hypotension, hyperreflexia, convulsions. Treatment supportive + naso-gastric tube and charcoal (up to 24 hours later). Monitor ECG, iv propranolol and NaHCO3 

·        Benzodiazepines: Diazepam, temazepam ® Post –OD “cerebellar syndrome” (dizziness, confusion, ataxia, nystagmus, bullous lesions). Supportive treatment 

·        Anticonvulscents: carbamazepine

·        Bronchodilators: theophylline 

·        Cocaine ® benzodiazepines 

·        Carbon Monoxide ® 100% oxygen, treat cerebral oedema. Presentation: pink, headache, vomiting, tachycardia, seizures, arrest 

·        Cyanide ® 100% O2 + cobalt edetate

·        Methanol and ethylene glycol poisoning ® correct acidosis, ethanol

·        Chelating agents for arsenic, copper, lead, iron, cyanide

·        Aspirin: risk is pH balance


Study Material, Lecturing Notes, Assignment, Reference, Wiki description explanation, brief detail
Medicine Study Notes : Emergency Management : Poisoning and Overdose - Emergency Management |

Privacy Policy, Terms and Conditions, DMCA Policy and Compliant

Copyright © 2018-2024 BrainKart.com; All Rights Reserved. Developed by Therithal info, Chennai.