Concise summary of the Emergency Tx of Poisoning

16 – Emergency Tx of Poisoning



 Both hypo- and hyper-thermia require
Chapter 16 – urgent hospitalisation
Emergency Tx of Convulsions
Poisoning  Single, short-term convulsions (<5mins) =
no Tx required
GENERAL CARE  If convulsions are frequent = diazepam or
lorazepam should be given via slow IV
 Consult TOXBASE or UK National Poisons injection into the large vein
Information Service  Alternatives = midazolam oromucosal
 Delayed action poisons = aspirin, iron, solution via buccal route or diazepam via a
paracetamol, TCAs, co-phenotrope rectal solution
Respiration  Avoid BZPs via IM route for convulsions
 Often impaired in unconscious Pts Methaemoglobinaemia
 In absence of trauma – open airway using  Tx if methaemoglobin conc. is >30% or if
chin lift or jaw thrust tissue hypoxia present despite oxygen =
 Consider intubation and ventilation if methylthioninium chloride
airway cannot be protected or respiratory  Works to reduce ferric iron of
acidosis is present due to poor ventilation methaemoglobin back to ferrous iron of
Blood pressure haemoglobin
 Hypotension is common in severe poisoning  High doses can cause methylthioninium to
with CNS depressants result in methaemoglobinaemia
 Systolic BP of <70mmHg = irreversible brain POISON REMOVAL AND ELIMINATION
damage or renal tubular necrosis
 Correct hypotension by raising foot of the Activated charcoal
bed and NaCl infusion  Given by mouth, it binds to many poisons in
 Hypertension may be associated with the GI system hence reduces absorption.
sympathomimetics like amphetamines,  The sooner it’s given, the more effective it is
phencyclidine and cocaine and lasts for up to 1 hour post-ingestion
 Repeated doses can enhance elimination of
Heart
some drugs after they’ve been absorbed –
 Cardiac conduction defects and arrhythmias
carbamazepine, dapsone, phenobarbital,
may occur with TCAs, APs and some AHs
quinine, theophylline
 Correct underlying hypoxia, acidosis
 If vomiting occurs post-dosing, it should be
Body temperature treated (with anti-emetic) as it can reduce
 Hypothermia may occur in Pts who’ve been the efficacy of AC
deeply unconscious for a few hours esp.  AVOID for poisoning with petroleum
following OD with phenothiazines or distillates, corrosive substances, alcohols,
barbiturates. malathion, cyanides and metal salts incl.
 Hyperthermia may develop with CNS iron and lithium salts
stimulants and is managed by removing
Other techniques to enhance elimination:
unnecessary clothing and using a fan.
1. Haemodialysis – for ethylene glycol, lithium,
Sponging with tepid water helps to promote
methanol, phenobarbital, salicylates and
evaporation
sodium valproate
2. Alkalinisation of urine – for salicylates

, 16 – Emergency Tx of Poisoning


Removal from the GI tract (gastric lavage) sodium bicarbonate or magnesium sulfate.
 Consider gastric lavage only if a fatal Arrhythmias may occur for up to 12hrs
amount of a drug which cannot be adsorbed
by charcoal (e.g. lithium, iron) has been ANTIDEPRESSANT POISONING
ingested in previous hour Tricyclic ADs
 Carry out only if airway can be protected
adequately Features = dry mouth, coma, hypotension,
 AVOID if a corrosive substance or petroleum hypothermia, hyperreflexia, extensor plantar
distillate has been ingested responses, convulsions, respiratory failure,
cardiac conduction defects, arrythmias, dilated
Removal from the GI tract (whole bowel pupils, urinary retention, metabolic acidosis,
irrigation) hallucinations, agitation, delirium, confusion
 Used in poisoning with M/R or E/C
formulations, in severe poisoning with iron  IV lorazepam or diazepam – to treat
and lithium salts and if illicit drugs are convulsions
carried in the GI tract  Activated charcoal – given within 1hr of OD
reduces absorption of drug
ACUTE INTOXICATION WITH ALCOHOL  Sodium bicarbonate – can arrest arrythmias
or prevent them in extended QRS duration
 Features = ataxia, dysarthria, nystagmus,
drowsiness, coma, hypotension, acidosis SSRIs
 Aspiration of vomit and hypoglycaemia may
also occur Features = nausea, vomiting, agitation, tremor,
nystagmus, drowsiness, sinus tachycardia,
ASPIRIN POISONING convulsions, marked neuropsychiatric effects,
neuromuscular hyperactivity, autonomic
 Features = hyperventilation, tinnitus,
instability, hyperthermia, rhabdomyolysis, renal
deafness, vasodilatation, sweating
failure, coagulopathies
 Very severe poisoning = coma
Tx = activated charcoal within 1 hour to reduce
Tx – activated charcoal within 1 hour of
absorption and lorazepam, diazepam or
ingesting more than 125mg/kg aspirin
midazolam oromucosal solution to treat
 Replace fluid losses and give IV sodium convulsions
bicarbonate to enhance urinary salicylate
ANTI-MALARIAL POISONING
excretion (optimum urinary pH = 7.5-8.5)
 Correct plasma K+ conc. before giving Features = arrythmias (rapid onset) and
sodium bicarbonate as hypokalaemia may convulsions (intractable)
complicate urine alkalisation
ANTI-PSYCHOTIC POISONING
Tx for severe poisoning (>700mg/L) or in severe
metabolic acidosis – haemodialysis Phenothiazines

OPIOID POISONING Features = hypotension, hypothermia, sinus
tachycardia, arrhythmias, dystonia, convulsions
 Features = coma, respiratory depression,
pinpoint pupils  Correct hypoxia, acidosis to reduce
arrhythmias
Tx if there’s coma or bradypnea = naloxone  Procyclidine – to treat dystonia
 Norpropoxyphene – is reversed by naloxone. 2nd Gen APs
It has cardiotoxic effects hence consider