substance toxicity Flashcards
what precipitates lithium toxicity?
- dehydration
- renal failure
- diuretics (especially thiazides), ACEi/ARBs, NSAIDs and metronidazole.
features of lithium toxicity?
coarse tremor (a fine tremor is seen in therapeutic levels)
hyperreflexia
acute confusion
polyuria
seizure
coma
mx of lithium toxicity?
mild/moderate
IV fluids with isotonic saline, until euvolemic, then typically twice maintenance rate
monitor serum sodium closely (every 4 hours with serial lithium concentrations) if there is a concern about lithium-induced nephrogenic diabetes insipidus
mx of lithium toxicity?
severe
haemodialysis
what may trigger therophylline toxicity?
theophylline is metabolised by the cytochromes P450 enzymes located in the liver
acute illness and certain medications (e.g. ciprofloxacin, erythromycin) may inhibit these enzymes
features of theophylline toxicity?
vomiting
agitation
dilated pupils
tachycardia
hyperglycaemia
hypokalaemia
mx of theophylline toxicity?
antiemetics (e.g. ondansetron) should also be given
IV crystalloid for hypotension
correct hypokalaemia
benzodiazepines for seizures
IV beta-blockers for SVTs
definitive treatment is with haemodialysis
features of digoxin toxicity?
generally unwell, lethargy, nausea & vomiting, anorexia, confusion, yellow-green vision
arrhythmias (e.g. AV block, bradycardia)
gynaecomastia
key precipitating factor for digoxin toxicity?
hypokalaemia
mx for digoxin toxicity?
Digibind
correct arrhythmias
monitor potassium
MOA of digoxin?
Inhibits the Na+/K+ ATPase pump
when should digoxin levels be measured?
If toxicity is suspected, digoxin concentrations should be measured within 8 to 12 hours of the last dose
how do you prevent contrast-induced nephropathy?
IV 0.9% saline pre and post procedure
what is the most common endocrine disorder developing as a result of chronic lithium toxicity?
hypothyroidism
name an anti arrhythmic med which should be used with caution with digoxin?
Amiodarone may cause precipitation of digoxin toxicity - if starting amiodarone on a patient taking digoxin the dose should be reduced
what antihypertensive is safe tp give someone taking lithium?
amlodipine
what is the blood gas picture in salicylate overdose?
Early stimulation of the respiratory centre leads to a respiratory alkalosis whilst later the direct acid effects of salicylates (combined with acute renal failure) may lead to an acidosis. In children metabolic acidosis tends to predominate.
features of salicylate overdose?
hyperventilation (centrally stimulates respiration)
tinnitus
lethargy
sweating, pyrexia*
nausea/vomiting
hyperglycaemia and hypoglycaemia
seizures
coma
treatment of salicylate overdose?
general (ABC, charcoal)
urinary alkalinization with intravenous sodium bicarbonate - enhances elimination of aspirin in the urine
haemodialysis
indications for haemodialysis in salicylate overdose?
serum concentration > 700mg/L
metabolic acidosis resistant to treatment
acute renal failure
pulmonary oedema
seizures
coma
