Acute poisoning

Investigations

• Glucose
• Urea & Creatinine
• Electrolytes
• CBC
• LFT
• INR
• ABG
• ECG
• Paracetamol, and salicylate levels
• Urine/serum toxicology
• Specific assays as appropriate

Emergency Management (general measures)

1. ABC
2. Clear airway
3. Consider ventilation (if the respiratory rate is <8/min, or PaO₂ <60mmHg, when breathing 60% O₂, or the airway is at risk, e.g. GCS ≤ 8)
4. Treat shock (see shock article)
5. If unconscious, nurse semi-prone

Further Management

6. Assess the patient
7. History from patient, friends, or family is vital
8. Features from the examination may help
9. Do Investigations
10. Monitor: T°, pulse, and respiratory rate, BP, O₂ saturations, urine output ± ECG
11. Supportive measures: may need catheterization
12. ↓Absorption: consider gastric lavage ± activated charcoal (see below)
13. Specific measures (see below)
14. For antidotes (see below)
15. Consider naloxone if ↓conscious level and pin-point pupils
16. Consider Vitamin B complex, vitamin C, and glucose if drowsy/confused

Specific Points

Plasma Toxicology:

• For all unconscious patients, measure paracetamol, aspirin, and blood glucose levels.
• Additional tests may be required based on the suspected drug, with common ones including digoxin, methanol, lithium, iron, and theophylline.
• Urine screening for recreational drugs may be helpful in some cases.

GI Decontamination:

• Activated charcoal is preferred over gastric lavage for many drug poisonings.

Activated Charcoal:

• Reduces drug absorption from the gut when given as a single dose of 50g with water, especially for drugs like salicylates and paracetamol.
• It's given in repeated doses (50g/4h) to increase elimination of some drugs from the blood, e.g. carbamazepine, dapsone, theophyllines, quinine, phenobarbital, and paraquat.
• Lower doses are used in children
• Avoid use with petroleum, corrosives, alcohols, clofenotane, malathion and metal salts(e.g. iron, lithium).

Gastric Lavage: Rarely recommended. Avoid it if petroleum, corrosives, or if the patient is unconscious. Only proceed if advised by Toxbase or Poisons Information Service.

Procedure for Gastric Lavage:

• Rarely used
• Lavage after 30–60min may make matters worse
• Do not empty stomach if - Petroleum products - Corrosives such as acids, alkalis, bleach, descalers have been ingested (exception: paraquat), - Patient is unconscious or unable to protect their airway (unless intubated)
• Never induce vomiting.

Gastric emptying and lavage Process

1. If comatose, or no gag reflex, protect airway with cuffed endotracheal tube.
2. If conscious, get verbal consent.
3. Monitor O₂ sat.
4. Have suction apparatus to hand and working
5. Position the patient in left lateral position.
6. Raise the foot of the bed by 20cm.
7. Pass a lubricated tube (14mm external diameter) via the mouth, asking the patient to swallow.
8. Confirm position in stomach
9. Drain the gastric contents.
10. Check pH with litmus paper.
11. Perform gastric lavage using 300–600mL tepid water at a time.
12. Massage the left hypochondrium then drain fluid.
13. Repeat until no tablets in drained fluid.
14. Leave activated charcoal (50g in 200mL water) in the stomach unless alcohol, iron, Li+, or ethylene glycol ingested.
15. When pulling out tube, occlude its end (prevents aspiration of fluid remaining in the tube).

Hemodialysis:

• May be necessary for poisoning from ethylene glycol, lithium, methanol, phenobarbital, salicylates, and sodium valproate.

Some specific poisons and their antidotes

Benzodiazepines

• Flumazenil (for respiratory arrest) 200mcg over 15s; then 100mcg at 60s intervals if needed.
• Usual dose range: 300–600mcg IV over 3–6min (up to 1mg; 2mg if on ICU).
• May provoke fits. Use only after expert advice.

Beta-blockers

• Try atropine up to 3mg IV.
• If atropine fails
• Give glucagon 2–10mg IV bolus + 5% glucose then infusion of 50mcg/kg/h.
• Also consider including phosphodiesterase inhibitor infusions (e.g. enoximone 5–20mcg/kg/min).
• If unresponsive, consider pacing.

Cyanide

• 100% O₂
• GI decontamination
• If mild, supportive care is usually sufficient.
• If moderate/severe then specific treatment to bind cyanide is required.
• Give sodium nitrite/sodium thiosulfate, or dicobalt edetate 300mg IV over 1min, then 50mL 50% glucose IV (repeat once if no response after a minute);
• or hydroxocobalamin 5g over 15min repeated once if required.
• Get expert help.

Carbon monoxide

1. Remove the source
2. 100% O₂ until COHb <10%
3. Metabolic acidosis usually responds to correction of hypoxia.
4. If severe, anticipate cerebral oedema and give mannitol IVI
5. Confirm diagnosis with ABG quickly as levels may soon return to normal
   • which will show low SaO₂ and high COHb (normal <5%).
6. SpO₂ from a pulse oximeter may be normal
7. Monitor ECG
8. consider hyperbaric O₂ If:
   • COHb >20%,
   • patient has neurological or psychological features, or cardiovascular impairment, fails to respond to treatment, or is pregnant
9. Get expert help.

Digoxin

1. If serious arrhythmias are present
2. Correct hypokalaemia
3. Inactivate with digoxin-specific antibody fragments (DigiFab/Digibind), If load or level is unknown, give 20 vials (800mg)—adult or child >20kg.
4. Get expert help.

Iron

1. Desferrioxamine 15mg/kg/h IVI; max 80mg/kg/d.
2. Gastric lavage if iron ingestion <1h, Consider whole-bowel irrigation
3. Get expert help.

Oral anticoagulants

1. If major bleed, give vitamin K 5mg slow IV and prothrombin complex concentrate 50U/kg IV (or if unavailable, fresh frozen plasma 15mL/kg IVI).
2. Get expert help

Opiates

1. Give naloxone, e.g. 0.4–2mg IV;
2. repeat every 2min until breathing is adequate (it has a short t½, so it may need to be given often or IM; max ~10mg).
3. Naloxone may precipitate features of opiate withdrawal—diarrhea and cramps, which will normally respond to diphenoxylate and atropine (e.g. co-phenotrope).
4. Sedate as needed.
5. High-dose opiate misusers may need methadone (e.g. 10–30mg/24h PO) to combat withdrawal.
6. Get expert help

Phenothiazine poisoning (e.g. chlorpromazine.)

1. No specific antidote
2. For Dystonia: try procyclidine, e.g. 5–10mg IM or IV.
3. Treat shock by raising the legs (± plasma expander IVI, or inotropes if desperate).
4. Restore body temperature
5. Monitor ECG
6. Use lorazepam IV for prolonged fits in the usual way
7. Neuroleptic malignant syndrome: maybe treated by
   • Cooling.
   • Dantrolene 1–2.5mg/kg IV (max 10mg/kg/day)
   • Bromocriptine and Amantadine are alternatives
8. Get expert help

Carbon tetrachloride poisoning

1. IV acetylcysteine may improve prognosis.
2. Get expert help

Organophosphate insecticides

1. Wear gloves
2. Remove soiled clothes
3. Wash skin
4. Take blood (CBC and serum cholinesterase activity).
5. Give atropine IV 2mg every 10min till full atropinization (skin dry, pulse >70, pupils dilated).
6. Up to 3d treatment may be needed.
7. Also give pralidoxime 30mg/kg IVI over 20min, then 8mg/kg/h, max 12g in 24h.
8. Even if fits are not occurring, diazepam 5–10mg IV slowly seems to help.
9. Get expert help

Paraquat poisoning (Found in weed-killers.)

1. Diagnose by urine test.
2. Give activated charcoal at once (100g followed by a laxative, then 50g/3–4h).
3. Get expert help.
4. Avoid O₂ early on (promotes lung damage).

Ecstasy poisoning (hallucinogenic substance)

1. There is no antidote and treatment is supportive.
2. Management depends on clinical and lab findings, but may include:
3. Administration of activated charcoal and monitoring of BP, ECG, and temperature for at least 12h (rapid cooling may be needed).
4. Monitor urine output and Urea, Creatinine, & Electrolytes, Liver Function Test, CK, CBC, and coagulation. Metabolic acidosis may benefit from treatment with bicarbonate.
5. Anxiety: lorazepam 1-2mg IV as a slow bolus into a large vein. Repeat doses may be administered until agitation is controlled.
6. Narrow complex tachycardias in adults: consider metoprolol 5mg IV.
7. Hypertension can be treated with nifedipine 5–10mg oral or phentolamine 2–5mg IV. Treat hypotension conventionally.
8. Hyperthermia: attempt to cool, if rectal T° >39°C consider dantrolene 1mg/kg IV (may need repeating: discuss with your senior and a poisons unit). Hyperthermia with ecstasy is akin to serotonin syndrome, and propranolol, muscle relaxation, and ventilation may be needed.

Snakes (adders)

1. Anaphylaxis: (see anaphylaxis article).
2. Tests: high WBCs, abnormal clotting; low platelets; Urea, Creatinine & Electrolytes; high urine RBC; high CK; low PaO2, ECG.
3. Avoid active movement of affected limb (so use splints/slings).
4. Avoid incisions and tourniquets
5. Get help from local/national poisons service
6. If antivenom indicated (IgG from venom-immunized sheep): e.g. 10mL IV over 15min (adults and children) of European Viper Antiserum—20mL if severe envenoming
7. have adrenaline to hand.
8. Monitor ECG.