Random Toxicology

susiewabisabi's version from 2015-10-17 01:00

High dose insulin

Question Answer
How do you start HDIT?Correct K, 50mls 50% dextrose, 1U/kg Actrapid
Then what50mls 50% glucose per hr, 0.5u/kg/hr up to 1 unit/kg/h actrapid, half hrly BSL, hrly bloods at least, correct K prn, titrate Glucose to euglycaemia, titrate insulin to BP and ECG
Indicationsdefinitely CCB, probably BB

B blockers

Question Answer
Which Bblockers are bad?Propanolol - QRS widening like TCA as Na blocker, sotolol increased QT, TdP (K blocker like amiodarone), coingestions
Effects of BB ODhypotension, bradycardia, AV block, bronchospasm, hypoglycaemia, hyperkalaemia, seizures (propanolol), torsades (sotalol)
Rx of BbockersFluids, atropine, isoprenaline, adrenaline, HDIT, NaHCO3 for wide QRS, Mg for TDP, benzos for seizures, GLUCOSE
Do Bblockers or CCB cause hypoglycaemia?BB = hypo, CCB hyperglycaemia

Ca Channel blockers

Question Answer
Which are the bad CCB?Diltazem and Verapamil esp if slow release 10 tablets - be aggressive with decontamination and expect significant sequalae
What dose of Calcium do you use in CCB OD?60mls 10% Ca gluconate, 20mls 10% Ca Chloride
Difference between those calciums?CaCl has more Ca which is immediately available (Ca gluconate has to pass liver), but scleroses tissues so preferably central line
Amlodipine/nifedipine?Mild tachycardia, no real hypotension, not life threatening but beware coingestions eg BB or digoxin, or extremes of age
Mx life threatening CCB ODearly intubation, charcoal, art line, CVL, 20ml/kg crystalloid, calcium x3 doses, atropine 0.6mg x5, noradr infusion, HDIT, external pacing, ECMO/IABP


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Thyroxine OD is it bad?Typically no major effects, mild symptoms 5-7 days afterwards therefore cardiac monitoring in first few days is not indicated


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How does sulphonylurea toxicity cause its effect?Hyperinsulinaemia that can show up within 8 hours and have a very long period of severe hypoglycaemia
How do you treat?not just glucose, need to give octreatide infusion as soon as become hypoglycaemic (not before), and usually run for 24hrs with 5-10% glucose infusion as well to maintain euglycaemia
How does octreatide work?Supresses insulin formation at Iselt cells
What is the problem of giving intermittent boluses go 50% glucose in these patents?High glucose level stimulates insulin release = worsened hypoglycaemia


Question Answer
What are the 5 stages of iron toxicity?1. 0-6hrs - direct corrosion GIT-diarrhea, vomiting, fluid losses, 2. 6-12hrs absorption of iron and less symptoms, 3. 12-48hrs - RAGMA, vasodilation, 3rd space losses, hepatorenal failure 4. 2-5days Acute hepatic failure, coagulopathy, hypoglycaemia - death, 5. 2-6 weeks - cirrhosis, GI strictures
How else (and more sensibly) can it be through of?direct GI corrosive effects and systemic effects
What is the dose expected to cause systemic effects? Elemental iron 60mg/kg. 20-60mg/kg is likely to cause just GI symptoms
What tests should you do in suspected iron toxicity?BSL, para, ECG, ABG - May have mixed metabolic RAGMA - Fe, NAGMA (diarrhoea) and alK as vomiting), lactate (B2 cause), AXR (to quantify amount), Serum iron level at 4-6hours -peak absorption - 500mcg/dL suggests systemic tox, falling venous bicarb can be used as a substitute if no iron levels available
4-6hr serum iron level that predicts systemic fox500mcg/dL or 90micromol/L
What is the treatment for Fe toxicity?Fluids and electrolyte replacement, desferroxamine iv until stable and serum levels reduced to 350mcg/dL
What are the indications for desferroxamine?>60mg/kg elemental iron, peak iron serum level >500mcg/dL, signs or symptoms of systemic fox - metabolic acidosis, altered mental state, shock and chronic iron overload
What are endpoints to cease rx? patient stability and serum iron <350mcg/dL. Avoid infusions >24hrs because or risk ARDS
How should desferoxamine be given?full cardiac monitoring, 500mg in 100mls saline, 15mg/kg/hr increased to 40 if severe and reduced if hypotensive. usually takes
Complications of desferroxaminehypotension esp at high dose, Toxic retinopathy, Hypersenstivity reaction, ARDS >24hrs, yersinia infections and other secondary infections
Is pregnancy a contraidication?NOPE


Question Answer
how does methaemoglobinaemia occur?oxidation of haem moiety fe2 (Hb) - fe3 (metHb)
Which drugs can cause metHb?Local anaesthetics, nitrates, nitrites, dapsone, sulfa and rifampicin. Recreational amyl nitrate - inhaled (poppers), sometimes mixed with cocaine or MDMA
What level of metHb is normal?physiologic levels of MetHb usually around 1-2%, mild 15-30%, mod 30-50%, severe life threatening 50-70%
population at risk?afroamericans
What effect does methhaemoglobinaemia have on Oxy/diss curve?Shift to left - unable to release O2. methhaemoglobiaema unable to carry O2
Symptoms and signs of methaemaglobinameia?grey blue skin, chocolate brown blood - DOES NOT CHANGE ON EXPOSURE TO AIR, pulse ox 85% (falsely high) due to similar wavelengths of oxyhaem and methaem, SaO2 on blood gas also falsely high a this is measuring partial pressure dissolved O2 in blood as well as that carried (or in this case not carried) by blood. This difference is known as being an increased oxygen saturation gap
What is needed to accurately measure SpO2?co-oximetry - can differentiate between, oxy-, deoxy-, carboxyl- and meathhaemaglobin
What is the treatment for methaemoglobinaemia?Methylene blue if metHb > 30%. Dose 1-2mg/kg iv over 5mins. Some thoughts on using NAC (no proven effect) Hyperbaric O2, exchange transfusion


Question Answer
ECG features of tricyclic overdoselarge terminal R in aVR, increased R/S ratio in aVR, long QT (>100 seizures, >160 VT)
Dose related risk assessment>10mg/kg potential for major effects, >30mg/kg severe prolonged toxicity
Rx of TCA ODearly intubation (seizures+vomiting), charcoal, HCO3 100mmol q2min, lignocaine 1.5mg/kg, noradr, hyperventilate to pH 7.5-7.55, benzos for seizures


Question Answer
risky (adult or paed >6yo) dose single ingestion > 200mg/kg or 10g (whichever is lower) over 8 hrs
risky dose repeated supratherapeutic>200mg/kg over 24h; OR >150mg/kg or 6g per 24h over 48hrs if asymptomatic; OR >100mg/kg or 4g per 24h if symptoms of liver toxicity
what is a massive overdose>50g or 1mg/kg (whichever is less) OR serum para more than double nomogram; OR hepatotoxicity; or iv para errors
activated charcoal immediate release para50 g activated charcoal should be administered to a cooperative, awake adult within 2 hours of ingestion of a toxic dose of immediate-release paracetamol AND up to 4hrs for massive OD.
modified release para within 4 hours of modified-release paracetamol ingestion; >4h for massive OD
early discharge for healthy kids under 6charcoal never indicated. Level 2h post ingestion < 150 mg/L, NAC not required, early d/c. Level 2h > 150 mg/L, repeat at 4h, start NAC if > 150 mg/L.
Rx within 2h single ingestionactivated charcoal, and measure serum para at 4h
Rx within 2-8 of single ingestionconsider charcoal, measure serum para within 4-8h and plot on nomogram, if over line start NAC, if under line no more treatment
Rx >8h post single ingestionstart NAC, mesaure serum para and ALT, if para below nomogram and ALT <50 then cease NAC, otherwise continue infusion
Rx staggered ingestiontiming of presentation is from the first dose, ie if first dose >8h start NAC
repeated supratherapeutic ingestionstreat with NAC if ALT >50 and serum para > 20. Repeat blds at 8h after first set and stop NAC if ALT<50 or not rising and para level <10 otherwise continue.
Reactions to NACrash, wheeze, mild hypotension occur in 10%–50% of patients during the first two infusions. Rx supportive, slow or pause infusion, antihistamines, bronchodilators prn. Recommence when symptoms settle.
Dose of NACtotal 300mg/kg over 21hrs. Continued at rate of last bag until safe to stop ie 100mg/kg over 16hrs.
Ceasing NACtowards end of infusion para level should be <10, and ALT < 50 and decreasing, INR <2
Kings college criteria (predicts fulminant hepatic failure needing liver Tx)INR >3.0 at 48 hours or >4.5 at any time; oliguria or creatinine >200 μmol/L; persistent acidosis (pH < 7.3) or arterial lactate >3 mmol/L; systolic hypotension BP < 80 mmHg, despite resuscitation; hypoglycaemia; severe thrombocytopenia; encephalopathy of any degree, or GCS <15 not associated with co-ingestion of sedatives.


Question Answer
risk assessmentpotentially lethal dose > 10mg adult, > 4mg child; level > 15nmol/L; serum K > 5.5 (hyperkalaemia important early sign of toxicity)
clinical featuresGIT (N and V), CVS (Bradycardia - slow AF or 1/2/3 degree HB; Increased automaticity - VEB, bigeminy, SVT, VT); CNS (confusion, lethargy)
Rx cardiac arrestdigibind 20 ampoules, ACLS; treat hyperkalaemia; atropine for AV block; lignocaine for VT
Is activated charcoal usefulyes within 1st hr overdose, may be difficult due to vomiting
Empiric dose digoxin immune Fab for acute toxicity5 if stable, 10 if unstable, 20 if cardiac arrest. Repeat every 30mins prn. Dilute in 100ml NS and give over 30mins.
Treatment of hyperkalaemiaNaHCO 100ml, insulin 10 + 50ml dex50%. Calcium is CONTRAindicated.
Dose of digibind for chronic toxicitycardiac arrest x5; otherwise x2
Adverse effects of digibindexacerbation of heart failure, increased ventricular response in atrial fibrillation, hypokalaemia. Uncommon, < 10%, generally not serious. ‘Allergic’ reactions are also rare, more common in atopy.


Question Answer
risk factors for severe toxicity>50mg/kg life threatening, all acute overdoses potentially toxic; chronic toxicity poor prognosis; elderly poor outcome
clinical featuresanxiety vomiting tremor tachy; SVT/AF/VT, hypotension, seizures; hypoK, hypoMg, hyperglycaemia, metabolic acidosis
are levels usefulyes correlate with severity, narrow therapuetic index, severe toxicity occurs at lower levels in chronic toxicity
Rxhypotension - fluids, noradr; seizures - benzos; SVT - BB; correct K; acute ingestion use activated charcoal; early haemodialysis in severe poisoning

Quick review

Question Answer Column 3 Column 4
metforminsevere type B lactic acidosis, usu in context of dehydration/renal failure or sepsis, rarely after overdose if renal function ok, up to 1.7g kids is benign, hypoglycaemia usu minor ECG, BSL, para, EUC, vbgABC, NaHCO, treat K, activated charcoal if >10g, haemodialysis
NSAIDsusually benign, minor GI symptoms; massive overdose >300mg/kg ibuprofen risk of acute renal failure, metabolic acidosis, multi organ failure
antipsychoticsincludes phenothiazines (chlorpromazine) and butyrophenones (droperidol, haloperidol); dose dependent CNS depr, hypotension, anticholinergic sxECG, BSL, parasupportive care of delirium, resuscitation, charcoal only after intubation
potassium>40 x 600mg tablets and pts with renal failure will need dialysis; early GI symptoms; K 6-8 lethargy, confusion, paraesthesia, hyporeflexia; K > 8 paralysis, bradycardia, cardiac arrestECG (peaked T waves, PR prolonged, loss of p waves, wide QRS, long QT, sine wave, asystole), EUC, AXR (SR tabs)CaCl, salbutamol, dex/insulin, NaHCO, haemodialysis and whole bowel irrigation
isoniazidrapid onset seizures, coma, severe metabolic acidosis, history of someone at home with TBECG, BSL, para, ABG (severe RAGMA, high lactate)seizures - benzos, chrcoal, dialysis (usu too late to be useful), iv pyridoxine 1g/g of isoniazid ingested
clonidinedrowsiness, miosis, bradycardiaECG, BSLs, pararesus, charcoal C/I due to CNS depression, try naloxone (except in opioid dependence)
quinine'cinchonism' nausea, vomiting, tinnitus, vertigo, deafness, >5g cardiotoxicity, blindness; > 2tabs in child potentially life threateningECG (Na channel blocker), BLS, para, visual field mappingNaHCO for dysrhythmias, Mg for TDP, benzos for seizures, charcoal, MDAC
colchicinepotentially lethal, severe gastroenteritis, BM suppression, multi organ failureECG, BSL, para, fluid&electrolyte&acid baseadmit all colchicine ODs, hypovolaemic shock - crystalloids, ABC, charcoal
chloral hydratecoma, dysrhythmiasECG and monitoring, BSL, para, gastroscopy for corrosive effectsearly intubation, BB for dysrhythmias, catecholamines CONTRAindicated


Question Answer
classic symptomsvomiting, tinnitus, hyperventilation, respiratory alkalosis, metabolic acidosis
risk assessment of dose>300mg/kg severe, >500mg/kg potentially lethal; salicylate levels correlate poorly with severity of toxicity
Rxintubate and hyperventilate, benzos for seizures, ivf, activated charcoal, urinary alkalinisation, haemodialysis
symptoms of chronic aspirin poisoningnon specific confusion, dehydration, metabolic acidosis, cerebral oedema (consider in elderly pts with altered mental status and metabolic acidosis)


Question Answer Column 3 Column 4
acute >25g, worse in renal failure or dehydrationgastroenteritis, delayed neurological symptomsECG, BSL, para, EUC, serum lithium level (confirm ingestion and monitor progress)fluid resuscitation, monitor renal function, NO charcoal, dialysis if renal failure or neurotoxicity
chronic due to impaired lithium excretion , eg decr renal function, dehydration, drug interactions (NSAIDs, ACEI, diuretics), hypoNaneurological - tremor, hyperreflexia then rigidity, hypertonia then coma, myoclonus; GI symptoms not prominentserum Li does not correlate with severity, EUC, TFTscorrect fluid and electrolytes, improve renal function, consider dialysis if established renal failure