180 Tox icolog y
SPECIFIC POISONS
2 Acute overdose
(i) Clinical manifestations of acute overdose include:
(a) gastrointestinal: anorexia, nausea, vomiting
(b) CNS: similar to chronic intoxication, but features develop
slowly enough for treatment with i.v. crystalloid therapy.
3 Chronic toxicity
(i) This is commonly associated with renal impairment,
dehydration, diuretic use and congestive cardiac failure.
(ii) Clinical manifestations of chronic toxicity include:
(a) CNS:
- mild: tremor, hyper-reflexia, ataxia, muscle weakness
- moderate: rigidity, hypotension, stupor
- severe: myoclonus, coma and convulsions
(b) gastrointestinal symptoms are not present in chronic
toxicity.
4 Gain i.v. access and send bloods for U&Es, blood sugar and serum lithium
level.
5 Perform an ECG.
MANAGEMENT
1 Acute overdose
(i) Do not administer activated charcoal.
(ii) Commence normal saline to correct hypotension, salt and water
deficits, and to maintain a urine output >1 mL/kg per h.
(iii) Most patients recover quickly with adequate fluid resuscitation.
Observe until they have a normal mental status, the serum
lithium level is falling and is <2.5 mmol/L.
(iv) Consider haemodialysis in a patient with impaired renal
function, late presentation, a serum lithium level of >3.5 mmol/L
or progressive neurological signs. Contact the ICU.
2 Chronic toxicity
(i) Discontinue lithium medications. Commence normal saline to
correct hypotension, salt and water deficits, and to maintain a
high urine output.
(ii) Refer the following patient to ICU for consideration of
haemodialysis:
(a) neurological abnormalities such as an altered mental state,
coma or convulsions
(b) serum lithium level of >3.5 mmol/L and significant
neurotoxicity.