Medical emergencies Flashcards
What is lithium used for?
Mood stabilising drug used prophylactically in bipolar disorder
What investigations should you do before starting lithium?
U+Es - to check renal function as it is excreted by the kidneys
ECG - to get baseline as lithium can cause changes
T4 levels - lithium can lead to thyroid dysfunction, so check levels
For lithium:
1. what is theraputic range?
2. at what concentration does lithium toxicity occur
3. how is it excreted?
- 0.4-1mmol/L
- 1.5 mmol/L
- via the kidneys
- How often should lithium levels be checked?
- In what patients do lithium levels need to be checked more frequently?
- Li+ to be checked weekly until dose has been constant for 4 weeks.
Then, check monthly for 6 months - if stable after this, can change to checking 3 monthly. - If on diuretics, NSAIDs, ACEi (all these drugs increase lithium in blood), low salt diet or if pregnant
What are common side effects of lithium? (not toxicitiy, just think of side effects)
From Ox Handbook and QuesMed
Hypothyroidism
Nephrogenic diabetes inspidus
Fine tremor
Dry mouth
GI disturbance
Increased thirst
Increased urination
Drowsiness
You check lithium levels and you see that they have been rising progressively over time. What does this suggest?
Progressive nephrotoxicity
What can lithium toxicity be precipitated by?
Dehydration
Renal failure
Drugs - diuretics (esp thiazides), ACEi, ARBs, NSAIDs, metronidazole
What are features of lithium toxicity?
- Coarse tremor
- CNS disturbance: Hyperreflexia, seizure, acute confusion, dysarthria,
- Polyuria
- Coma
- Arrythmias
- Visual disturbance
What is the management of lithium toxicity?
Largely supportive and needs specialist input
main aims of management = maintain electrolyte balance, monitor renal funcion, monitor seizure control
* mild-moderate toxicity - IV fluid resuscitation with normal saline.
* alkalisation of urine. (Note: alk of urine and fluid resus help enhance excretion of drug)
* severe toxicity / if renal function is poor - haemodialysis alongside everything else
* for agitation and seizures - use benzodiazepines if needed
What age bracket of patient shows increased sensitivity to lithium neurotoxicity?
the elderly
Neuroleptic malignant syndrome is caused by what drugs?
Atypical antipsychotic
May occur with dopaminergic drugs
Onset of neuroleptic malignant syndrome after taking the drugs?
Occurs hours- days after staring antipsychotics
Symptoms of neuroleptic malignant syndrome?
Rigidity
Pyrexia
Autonomic lability e.g hypertension, tachycardia, tachypnoea
Agitated delirium with confusion
Investigations for Neuroleptic Malignant Syndrome?
Creatinine Kinase: increased in most cases
WBC: Leukocytosis
U&Es: AKI secondary to rhabdomyolysis in severe cases
Management of Neuroleptic Malignant Syndrome?
Stop the antipsychotic
Transfer patient from psych ward to medical ward
IV fluids to prevent renal failure
Dantrolene
Bromocriptine (dopa agonist) may also be used
What is Acute Dystonia?
Adverse reaction to antidopaminergic, dopamine receptor antagonist e.g. antiemetics, antipsychotics, sometimes serotonergic agents
Features of Acute Dystonia?
Involuntary contractions of face, arm, legs and larynx
Extra pyramidal side effects- onset of atypical posture or position of muscles within minutes or hours of taking med
Torticollis: twisting of neck, causes tilt at wrong angle
Oculogyric crisis: involves ocular muscles
Investigations for Acute Dystonia?
Neuromuscular testing to examine range of motion, breathing and swallowing
Vaccination history to rule out tetanus
Blood tests: rule out hypocalcaemia (bone profile), hyperventilation (ABG/VBG), hypomagnesia, Wilson’s disease
Treatment of Acute Dystonia?
Stop causative medication
Anticholinergic agents- IV
Benzodiazepines- IV
Give procyclidine for this sustained muscle contraction (this drug is an anticholinergic)
What is Wernicke’s encephalopathy ?
a neuropsychiatric disorder caused by thiamine deficiency which is most commonly seen in alcoholics