Toxicological Emergencies




(1)
Royal Free NHS Foundation Trust, London, UK

 




ABCD assessment in poisoning





  • Airway: signs of obstruction (caustic ingestion; ACE inhibitors); loss of protective airway reflexes (CNS depression; seizures); increased secretions (organophosphates); risk of aspiration; predicted rapid progression to respiratory failure (paralysis-botulinum toxin; pneumonitis-hydrocarbons, inhalants)


  • Breathing: non-cardiogenic pulmonary oedema/acute lung injury


  • Circulation


  • Disability: GCS; mental state; pupil size and reaction; hypoglycaemia (ethanol, oral hypoglycaemic agents, beta-blockers, salicylates)


  • Exposure


Causes of altered heart rate associated with poisoning





  • Bradycardia: beta-blockers; calcium channel blockers; opiates; digoxin


  • Tachycardia: sympathomimetic agents (amphetamines, cocaine); alcohol; anti-cholinergic agents; salicylates; tricyclic antidepressants; theophylline


Causes of hypotension associated with poisoning





  • Vasodilatation, with venous pooling in the lower limbs: ACE inhibitors; calcium channel blockers


  • Myocardial depression: beta-blockers; calcium channel blockers; tricyclic antidepressants


  • Reduced circulating blood volume: gastrointestinal losses (vomiting: diarrhea); increased insensible losses (salicylates)


Screening evaluation with overdoses





  • History of overdose: what?, when?, how much?, what else?, why?


  • Collateral information: family/friends; paramedics; notes; contents of pockets; empty bottles


  • Recognition of medication: Toxbase; BNF; TICTAC (Tablet Identification Aids); NPIS; plant identification atlas


Potential sources of caustics





  • Acids: toilet bowl cleaners; anti-rust compounds; car battery fluid; stone cleaner; soldering fluxes


  • Alkalis: drain cleaners; surface cleaners; disc batteries; laundry or dishwasher detergents; denture cleaners; industrial strength bleach


Causes of toxidromes

(toxicological syndromes, consisting of a collection of physical signs that help identify the causative agent)



  • Sympathomimetic: beta adrenergic agonists (terbutaline); alpha adrenergic agonists (ergot alkaloids, phenylephrine), predominantly alpha-1 adrenergic agonists (ephedrine, pseudoephedrine); indirect acting (cocaine, amphetamines; methamphetamines); LSD; theophylline; caffeine; noradrenaline uptake inhibitors (MAOI);


  • Anticholinergic: antihistamines, antipsychotic agents, selective serotonin reuptake inhibitors, tricyclic antidepressants, atropine, scopolamine, benztropine


  • Cholinergic: organophosphate insecticides (nicotinic and muscarinic), neuromuscular blocking agents (nicotinic); chemical warfare nerve agents; carbamate insecticides (muscarinic); mushrooms (Boletus, Clitocybe and Inocybe species); nicotine containing products


  • Opiate (triad of miosis, hypoventilation and coma): codeine, heroin, methadone


  • Sedative-hypnotic: benzodiazepines; ethanol and other alcohols; barbiturates; quinazolines


  • Sedative withdrawal


  • Serotonin: serotonin breakdown inhibitors (monoamine oxidase inhibitors); serotonin reuptake inhibitors (SSRI; cocaine; opioids); serotonin precursors (LSD, L-tryptophan); serotonin release enhancers (amphetamine, atypical anti-psychotics: lithium, risperidone, olanzapine; atypical antidepressants: mirtazapine, venlafaxine); triptans


  • Alcohol withdrawal


Anti-muscarinic (anti-cholinergic) syndrome





  • Tachycardia


  • Dilated pupils(mydriasis)


  • Dry, flushed, hot skin


  • Dry mucous membranes/axilla


  • Urinary retention


  • Reduced bowel sounds: reduced peristalsis


  • Hyperthermia


  • Mild hypertension


  • CNS: Confusion, hallucinations, seizures, sedation, agitated delirium, myoclonic jerking and choreoathetoid movement, lethargy, coma


  • Cardiac arrhythmias


  • Absent bowel sounds

“Hot as hades, dry as a bone, red as a beet, blind as a bat, and mad as a hatter”


Features of tricyclic antidepressant toxicity

(the 3 Cs of cardiac complications, convulsions and coma)



  • Anticholinergic: dry mouth, dry and flushed skin, mydriasis, blurred vision, sinus tachycardia, hyperthermia, hallucinations, seizures, ileus, urinary retention


  • Sodium channel blockade: prolonged QT interval, AV blocks, widening of QRS complex with terminal R wave in aVR, ventricular arrhythmias (VT, VF)


  • Alpha-adrenergic blockade: hypotension; reflex tachycardia


  • Antihistamine: CNS sedation


Cholinergic (muscarinic) syndrome





  • Excessive salivation


  • Lacrimation


  • Bronchorrhoea


  • Bronchospasm; wheezing


  • Abdominal cramps: hyper-peristalsis


  • Urine and faecal incontinence


  • Vomiting


  • Sweating


  • Miosis


  • Bradycardia


  • Muscle weakness and fasciculations


  • Pulmonary oedema


  • Confusion or lethargy; coma


  • Seizures

Peripheral syndromes may be described as:



  • SLUDGE: salivation; lacrimation; diarrhoea; gastro-intestinal motility, emesis


  • BBB: bradycardia; bronchorrhoea; bronchospasm


Sympathomimetic (hyper-adrenergic) syndromes





  • Tachycardia


  • Tachypnoea


  • Hypertension; with severe hypertension, reflex bradycardia may occur


  • Hyperthermia


  • Sweating (diaphoresis)


  • Dry mucosae


  • Piloerection


  • Mydriasis


  • Hyperreflexia


  • Agitation


  • Delirium


  • Paranoid delusions


  • Seizures


  • Stroke


  • Acute coronary syndrome


  • Aortic dissection


  • Cardiac arrhythmias


  • Hyperactive bowel sounds


  • Rhabdomyolysis


Potential presentations with cocaine toxicity





  • CNS stimulation: tremors, euphoria, agitation, seizures, status epilepticus


  • Cardiovascular: hypertension; chest pain (acute coronary syndrome: ST elevation myocardial infarction); rhythm disturbances: ventricular tachycardia; supraventricular tachycardia; aortic dissection; dilated cardiomyopathy


  • Hallucinations; acute psychosis


  • Acute cerebrovascular accidents: cerebral infarction; subarachnoid haemorrhage; cerebral vasculitis


  • Pulmonary: bronchospasm; haemoptysis: alveolar haemorrhage; acute non-cardiogenic pulmonary oedema; hypersensitivity pneumonitis(crack lung); barotrauma: pneumothorax; pneumomediastinum (from coughing against a closed glottis while smoking or intranasally inhaling cocaine


  • Rhabdomyolysis: acute kidney injury


  • Gastrointestinal: bowel ischaemia; body packer syndrome; hepatitis


  • Obstetric and perinatal: spontaneous miscarriage, abruptio placentae, premature labour, neonatal cerebral infarction, neonatal seizures, neonatal myocardial infarction


Opioid toxidrome





  • Bradycardia


  • CNS depression


  • Reduced gastro-intestinal motility


  • Hypotension


  • Miosis


  • Respiratory depression: bradypnoea, apnoea


  • Hypothermia


Sedative-hypnotic toxidrome





  • Bradycardia


  • CNS depression-lethargy, obtundation


  • Hypotension


  • Hypothermia


  • Respiratory depression


  • Normal to large, sluggishly reactive, pupils


  • Paradoxical excitement


  • Slurred speech


  • Ataxia

Benzodiazepines:



  • CNS depression


  • Normal vital signs


  • No respiratory depression in oral overdose without concomitant CNS depressants

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Nov 20, 2017 | Posted by in Uncategorized | Comments Off on Toxicological Emergencies

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