Toxicology - CVS Flashcards
Management of severe calcium channel blocker overdose
IV fluid loading
Calcium gluconate 10%, 60 mls over 5-10 min, x3 Q20 min
Adrenaline infusion 1 mcg/kg/min (up to 60/70)
High dose Insulin Euglycaemic therapy (cardgiogenic shock)
Noradrenaline
Methylene blue (vasoplegic shock)
ECMO
How to administer high dose insulin euglycaemic therapy
50 mls of 50% glucose 1 unit / kg IV rapid acting insulin then infusion via CVC of 25g / hr glucose 0.5 units/kg/hr IV insulin, up to 1-2 u/kg/hr Replace potassium
Indications for digoxin fab fragments
Hyperkalaemia > 5 / 5.5
Ingestion of > 10g / 4g in child
Haemodynamically unstable / arrest
Serum digoxin concentration > 15 nmol/L
Dosing of digoxin fab fragments
1 ampoule = 40 mg 40-80 mg reasonable and reassess calc: dose (mg) x 0.8 x 2 unstable - 10 ampoules arrest - 20 ampoules
Benzodiazepine for sedation in setting of delirium
5mg IV diazepam every 5-10 min
Management of toxicological seizures
A/B/C
Check BSL
IV diazepam 5-10 min over 3-5 min
2nd line barbiturate (phenobarbitone 100-300 mg/kg slow IV (10-20 mg/kg)
3rd: pyridoxine if due to isoniazid or hydrazine 70mg/kg to 5g
Temperature threshold for intubation and active cooling in toxicological hyperthermia
39.5 deg
Name the receptors and side effect involved for various features of antipsychotic overdose
- Dopamine antagonist - muscle rigidity, bradykinsia, temperature regulation
- Muscarinic - delirium, tachycardia, urinary retention
- Histamine - sedation, hypotension
- Alpha adrenergic antagonist - vasodilation / hypotension
- Sodium channel blockade - wide QRS
Features of NMS
Altered mental status
Hyperthermia
Autonomic dysfunction
Muscle rigidity
Dose of quetiapine with significant symptoms expected and treatment
> 3g
Require intubation / ICU admission
IV fluids
Noradrenaline for hypotension (not adrenaline)
Discharge criteria for quetiapine overdose
< 3g, discharge at 4 hrs when well with normal ECG (or 8 hrs if XR) and not at night and psychiatric risk assessment completed.
SSRI antidepressant and threshold for seizures / long QT, change in management compared to other SSRI
Escitalopram 300mg
Citalopram 600 mg
Administer charcoal up to 4 hrs
Cardiac monitor to 8 hrs (12 if > 500/1000 mg) compared to 6 hrs.
Risk assessment in TCA overdose
> 10 mg/kg significant clinical toxicity
> 20/30 mg/kg: coma, hypotension, seizures and arrhythmias.
ECG changes and implication in TCA overdose
R wave > 3 mm, R/S ratio > 0.7 in aVR - seizures / arrhythmias
QRS width > 100 msec - seizures
QRS with > 160 msec - ventricular arrhythmias
Long QT - not predictive clinical toxicity
Management of TCA overdose
Secure airway (decrease consciousness, < GCS 12)
Hyperventilation
Sodium bicarbonate 8.4 %, 1-2 mEq/kg, to pH 7.5-7.55
Hypotension: IV fluid, noradrenaline
Resistant arrhythmia with pH >7.5, lignocaine 1.5 mg/kg IV
Indications for sodium bicarbonate in TCA overdose
Cardiovascular dysfunction
- QRS > 100 msec
- Hypotension unresponsive to fluid
- Any arrhythmia
Symptoms and management in acute lithium overdose
Nausea, vomiting, diarrhoea. Supportive care Correct sodium / water deficit Rarely particularly toxic Check level 6 hourly
Symptoms and mangement in chronic lithium toxicity
Neurological symptoms - tremor, hyperreflexia, agitation, ataxia –> stupor, rigidity, coma.
Worse if dehydration, hyponatraemia or renal failure.
Haemodialysis if level >4 with renal failure, severe symptoms, of [Li] > 5 mEq/L
4 phases of paracetamol toxicity
1: asymptomatic, N/V
2: 1-2 days - hepatotoxicity develops, RUQ pain and abnormal ALT/AST and INR
3: 3-4 days - fulminant liver failure, coagulopathy, metabolic acidosis, jaundice, encephalopathy, death.
4: recovery
Factors associated with higher risk in paracetamol overdose
Liver enzyme induction agents Liver impairment pre-existing Chronic alcohol ingestion Starvation / prolonged fasting Slow release preparations Massive ingestion (>500mg/kg, >30g, level > 450 mg/L) Multiple ingestions Unknown time of ingestion
Treatment of IR paracetamol, presenting < 8 hrs
Paracetamol level, commence NAC based on level. no further bloods unless high risk group.
Treatment of IR paracetamol presenting 8-24 hrs
Commence NAC.
Paracetamol level and LFTs.
Cease if paracetamol level < nomogram and normal LFTs, otherwise complete 20 hr course.
LFTs repeated at 18 hrs.
Further 100mg/kg/16 hrs if AST/ALT rising.
Treatment of IR paracetamol presenting > 24 hrs
Commence NAC
Prolonged therapy if LFTs rising at 18 hr bloods. Continue at 100 mg/kg/12 hrs until INR / LFTs normalising or transplant.
Treatment of IR paracetamol with unknown timeframe of ingestion
Commence NAC.
Stop at 20 hrs if LFTs normal and paracetamol negative.
Treatment of staggered acute overdose
Assume total dose taken at earliest time.
Paracetamol level, commence NAC prior to level if > 8 hrs.
NAC treatment based on assumption of whole dose at earliest time.
Supratherapeutic ingestions warranting treatment
> 10 g or 200mg/kg over 24 hrs
6 g or 150 mg/kg over 48 hrs
4 g or 100 mg/kg with risk factors (liver impairment)
Management of slow release paracetamol overdose
Commence NAC if > 200 mg/kg
Paracetamol level at 4/presentation + 4 hrs.
If both below level & decreasing, stop.
If increasing / above nomogram - continue for 20 hrs.
Recheck LFTs and paracetamol at 18 hrs.
Management of massive paracetamol ingestion
> 500mg/kg, > 30g, level > 450 mg/L
200 mg/kg NAC over 4 hrs
200 mg/kg NAC over 16 hrs (increase from 100mg/kg)
Factors associated with poor prognosis / referral to liver treatment unit
INR > 3 at 48 hrs or > 4/4.5 at any stage pH < 7.3 after resuscitation Hypoglycaemia Encephalopathy Severe thrombocytopaenia Cr > 200 SBP < 80 Rising serum lactate
Management of salicylate toxicity
Alkalinise urine (if symptomatic), target pH > 7.5 Loading dose of sodium bicarb 0.5-1 mEq/kg IV, then infusion of 100-250 mEq/kg/hr Replace potassium Maintain urine output 1-2 mls/kg/hr
Haemodialysis if indicated (worsening, renal failure, end organ failure, level > 6 mmol/L)
If intubation - the give Sodium bicarb loading and hyperventilate.
Management of sulphonylurea overdose
Correct hypoglycaemia
- 50 mis of 50% glucose or 5 mls/kg of 10 % glucose, then infusion
Suppress endogenous insulin release
- octreotide 50 micrograms IV (1mcg/kg), then 25 mcg/hr (1mcg/kg/hr)
Indications for dialysis in metformin overdose
Lactate > 10
Worsening acidosis
Worsening renal failure
Clinical deterioration
Risk assessment in colchicine overdose
<500 mcg/kg: GI symptoms
500-800 mcg/kg: BM suppression, 10% mortality
> 800 mcg/kg: CVS collapse, 100% mortality
Describe the 3 stages of colchicine overdose
1: GIT - N/V/D/Abdo pain, dehydration and hypotension
2: 24-72 hrs - multi organ failure (Resp - ARDS, CVS - failure/arrhythmia/arrest, Haem - DIC, fever, ileum, renal failure)
3: 6-8 days - recovery, leucocytosis, alopecia
GIT symptoms rapidly progressing to multi organ failure
Think of colchicine!
