Calcium Channel Blocker Overdose
4/11/10
PY Mindmaps
- high mortality
- SR preparation can cause delay of onset of toxicity (up to 12 hours)
- effects: vasodilation, profound myocardial depression, profound conduction abnormalities
CLINICAL FEATURES
-
CVS effects: hypotension, bradycardia, shock
RESP: pulmonary oedema,
METABOLIC: hyperglycaemia, hypokalaemia
RENAL: failure
GI: nausea and vomiting
NEURO: seizures, myoclonus, dizziness, syncope, focal deficits
INVESTIGATIONS
- ECG:
->
->
->
->
->
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bradycardia
accelerated AV node conduction
2nd and 3rd degree HB
sinus arrest with nodal escape
asystole
hyperglycaemia is a marker of severity
ABG: oxygenation, tissue perfusion, K+
CXR: APO
Ca2+ level (often normal)
MANAGMENENT
Resuscitation
A: intubate if agitated or unrousable and requires airway protection, haemdynamically
unstable
B: lung protective ventilation, O2
C: IV fluid load, CaCl, inotropes, invasive monitoring
Evaluation
History: timing, type of ingestion (SR prepartions), amount, co-ingestion, other medications
available, psychiatric history
Examination: cardiovascular and neurological assessment
Investigations: above + ABG, CXR, ECG, lactate, renal function, FBC, Ca2+ (ionized),
paracetamol, urine toxicology
Jeremy Fernando (2011)
Treatment
Specific (support cardiovascular system)
-
Ca2+ chloride 1-3g -> 2-6g/hr (maintain ionized Ca2+ between 2-3mmol/L)
glucagon 5-10mg bolus -> 2-5mg/hr
atropine
isoprenaline 2mcg/min
adrenaline 0.1-1mcg/kg/min
noradrenaline 0.1-1mcg/kg/min
milrinone
levosimendan
pacing to achieve ventricular capture @ 50-80/min
- euglycaemic hyperinsulinaemia
-> insulin-glucose infusions
-> LD: 0.1u/kg insulin + 50mL 50% dextrose
-> infusion - 0.2-0.5u/kg/hr of insulin + 0.5g/kg/hr glucose
-> mechanism: calcium channel blockers disrupt fatty acid metabolism and create insulin
resistance in myocardium -> high dose insulin can overcome this state
- lipid emulsion: may bind calcium channel blockers in plasma and prevent myocardial
penetration
- intra-aortic balloon pump
- VA ECMO or cardiopulmonary bypass
General
- decreased absorption: activated charcoal, consider gastric lavage in presented soon after
ingestion
- increased elimination: whole bowel irrigation (Kleen prep, Go litely, Polyethylene glycol),
charcoal haemoperfusion for verapamil
- hyperglycaemia -> insulin
Disposition
- ongoing ICU observation and monitoring
- liaison with the family
- psychiatric referral
Jeremy Fernando (2011)