Toxicology pgy 1+2 2013

Dr Chris CresswellFACEM

Whanganui New Zealand

The Bible

TOXINZ.com

General approachResuscitate if neededRisk assessment – is what they have taken dangerous?Supportive Care and Monitoring

depending on your risk assessment Investigations

Everyone: Paracetamol level ECG

Other as indicatedDecontamination – very rareAntidotesEnhanced elimination - rareSeek and treat complicationsDisposition – usually psych. Psych does the psych risk

assessment for us.

Toxinology

Critters rather than drugs/chemicals

We have one rare annoying, non-life threatening spider in NZ.

Katipo = red back – painful bite and sweating +/- back pain -> analgesia + antivenom.

Controversial whether antivenom actually works.

Toxicology

Drugs and chemicals

Not going to cover them all!

Toxidrome

What’s a toxidrome?What are some examples?

Toxidrome

Clinical toxicological syndromeie you can examine a patient +/- look at their

ECG or other bedside tests and get a good idea of what they have taken

EgOpioidAnticholinergicCholinergic syndromeSerotonin syndromeNa channel blockade

ToxidromesOpioid: resp depression, decr LOC, miosisAnticholinergic: hot as a hare, mad as a hatter, red as

a beet, dry as a bone eg daturaCholinergic syndrome eg organophosphate, nerve gas

SLUDGEM: salivation, lacrimation, urinarination, diarrhoea, GI upset, emesis, miosis + muscle spasm

Or DUMBELLS: diarrhoea, urination, miosis/muscle weakness, bronchorrhoea/bradycardia, emesis, lacrimation, salivation/sweating

Serotonin syndrome eg SSRI: sweating, agitation, increase muscle tone, fever

Na channel blockade eg tricyclic: hypotension, decr LOC, widened QRS

Rapidly alternating apnoea and coma eg GHB

Tox examHRRRPupil size and reactivity and look for nystagmusArmpits for sweatReflexes and test for clonusTemp

ECGBSL

Labs: almost everyone gets a paracetamol level Cheap test. Treatment very efficacious.

Some specific drugs / chemicals

Common or important ones.

Paracetamol/acetominphenNB different units from UKCommonAlmost always reversible with antidoteHigh survival even from liver failureHow to you risk stratify and treat these

ingestions?What is the antidote?

Paracetamol/Acetominophen Most common scenario: single ingestion, reasonable idea of time. < 10g or 200mg/kg ingested within 8 hours does not need

investigation Otherwise or unknown:

< 2 hours post ingestion of non-liquid and cooperative patient -> single dose activated charcoal.

< 4 hours post ingestion: wait and take blood for paracetamol level at 4 hours post ingestion. N-acetylcysteine (NAC) if over 1000µmol/L.

4-8 hours. Take level. NAC if over threshold on nomogram. 8-24 hours. Take level and start NAC. Stop treatment if under

treatment threshold. 24+ hours or unknown. Take level, VBG, LFT, glucose, INR,

renal function. Start NAC. Stop NAC if ALT normal. If liver failure d/w liver unit

Paracetamol

Multiple dosesLook it up

NACN-acetylcysteineVery safe and effectiveBoxes in ED with dose schedule written on them

3 different rates over 24 hoursFairly frequent anaphylactoid reaction

Eg erythema, urticaria, pruritis, hypotensionThought to be from histamine release rather than

true anaphylaxisIf mild reaction half rate +/- give IV antihistamineIf severe reaction. Stop infusion. Give IV

antihistamine +/- bronchodilators, fluids etc. Once asymptomatic for 1 hour restart infusion at ¼ rate and titrate up

DispositionIn this hospital all patients requiring NAC get

admitted to ward under medical team. Inform psych of admission. They say they

will see patient before “medically cleared”

SSRIsWhat do you need to know about these?

SSRIsUsually no significant toxicityMain risk is serotonin syndrome

What is serotonin sydrome?

Serotonin SyndromeRareExcess serotonin usually from over dose of SSRI

or combination of serotonergic agentsEg

SSRI, St John’s wortAntipsychoticsLithiumPethidineTramadolLSDEcstacy and other amphetamines

Serotonin SyndromeSerotonergic drug +Mild: Tremor, anxiety, nauseaModerate: agitation and hyperreflexia and

clonusSevere: severe: fever, seizures, respiratory

failure, rhabdomyolysis, renal failure, DIC

Serotonin syndromeManagement

Mild: observe for 4-6 hoursModerate: IV fluids, benzodiazepine, +/-

cyproheptadineSevere: cooling, IV benzodiazepine, IV fluid.

May need RSI

So for all overdoses of serotonergic agent need ...Record

TemperatureTone Reflexes Clonus

CCB and Beta Blocker

Cause ?

CCB or Beta Blocker

Hypotension and bradycardiaMost beta blockers fairly benign

Exception: propranolol: Na channel blocking effect: manage as for tricyclic + Beta blocker

Calcium channel blockers: nasty

Treatment?

Beta blocker + CCBResuscitate if required: ABCsRisk assessment: look up to see how toxic the dose

could be.Supportive care and monitoring: if moderate risk:

resus bay, IV access, cardiac monitoring, IV fluids, trial of atropine, calcium gluconate, pressors eg dopamine. If high risk likely to need intubation

Investigations: ECG, paracetamol level, lactate, glucose.

Decontamination: Whole bowel irrigation likely to be needed eg Polyethylene glycol via NG tube

Beta blocker + CCB

Antidote/specific treatments: could call calcium an antidote to CCB, glucagon 5mg IV, high dose insulin 1 unit/kg then 1unit/kg/hour

Enhanced elimination: dialysis ineffective. Multidose activated charcoal may be effective for CCB.

Seek and treat complications: Likely to need ICU care. Monitor for MOF, rhabdo etc

If all of the above wasn’t working what else could be done?

Intraarterial balloon pumpBypass/ECMO

Most life threatening drug ingestions cause temporary CVS collapse – if we can support them through this the patient should do well

SulphonylureasLife threateningAntidote?

SulphonylureasAntidote: IV glucose then IV octreotide

IronWhat’s important about ironWhat’s the antidote

IronCan be life threatening and yet the patient is

asymptomatic, or has recoveredLook it upMost accidental ingestions not harmfulOver a threshold ingestion -> iron levels

usefulLow threshold for whole bowel irrigationAntidote: desferoxamine

Digoxin

What are the 2 main types of toxicity?What are the classic signs and symptoms?What is the antidote?

Digoxin2 main types of toxicity:

Acute ingestion – rare Chronic – usually due to dehydration/renal impairment

Consider this in any patient on digoxin who is unwell. Check ECG, K+ and digoxin level

Classic signs and symptoms Yellowed vision Nausea and vomiting Confusion Cardiac automaticity (ectopics or tachyarrythmia) and block

What is the antidote? Digoxin FAB fragments – “digibind” Expensive but cost effective

Indications for Digoxin FAB

Hemodynamically unstable or life-threatening dysrhythmia,

Hyperkalemia > 6 mmol/L (6 mEq/L)Plasma digoxin level > 20 nmol/L (15.6

ng/mL) at 6 hours post-ingestionDigoxin level > 10 nmol/L (7.8 ng/mL) or

elevated digoxin level + renal impairment + symptoms in chronic toxicity

Local anaesthetic

Eg femoral nerve block -> intraarterial

Classic signs?

Local anaesthetic

Perioral tingling

Others: Visual disturbanceSeizureVT

Antidote?

Local anaesthetic

Intralipid? Lipid sink? Cardiac fuel

Tricyclic / propranalol

Na channel blockadeNasty

HypotensionDecr LOCSeizureDysrhythmias

Antidote?

Na channel blockade"Prompt intubation, hyperventilation and

administration of administration of sodium bicarbonate at the first evidence of severe toxicity is life-saving"

Na channel blockade from TCA

Blue apnoeic patient dumped at the front door.

He has pin point pupils

How will you manage this patient?

IV opioid toxicity

Lots of techniques

BVM ventilate

400mcg IM naloxone200mcg IN naloxone

Oral opioid toxicity

If significant respiratory/LOC depression usually require naloxone infusion

Titrate IV nalaxone boluses to get just adequate reversal – don’t make the patient withdraw and run

Infusion of 2/3 of reversal dose/hour

Rare but nasty

Theophylline -> vomiting +++ -> needs urgent dialysis

Ethylene glycol

Neuroleptic Malignant SyndromeWhat is it?What do you do about it?

Neuroleptic malignant syndromeRareUsually an idiosyncratic reaction to

standard/high doses of antispychotic rather than a result of overdosage.

Life threatening“Malignant Parkinson’s”

Parkinsonism + fever + autonomic instabilityDoesn’t have the agitation, hyperreflexia or

clonus of serotonin syndrome

Neuroleptic malignant syndromeIf temp > 39.5 or rigidity compromising

ventilation -> RSICool to 38-39˚BenzodiazepinesTreat hypoglycaemiaBromocriptine +/or dantrolene

“My child might have taken some of granny’s pills”

Try to work out what Granny is onDefault

Blood sugarBPECGIf abnormal or toxidrome: IV line and treat

empirically.If normal: Observe 12 hours. Discharge if BP and

BSL normal

BenzodiazepinesAntidote – when do we use it?

FlumazenilAntidote to benzosAlmost never usedOnly used if we caused the ODFor chronic benzo users or coingestion with a

proconvulsant (eg TCA) flumazenil may cause seizure

Benzos almost never need treatment or intubation

Recovery position, wait for them to wake up

AlcoholAlmost never needs intubationRecovery position and observeLOC should improve hourly – if not consider

other diagnosis eg head injury

Activated charcoalAlmost never usedLittle proof of efficacyHas killed people - aspiration

Hydrofluoric acidNasty. 2% BSA exposure can kill

WarfarinVitamin K and prothrombin complex

(prothrombinex)

InsulinGlucose + foodOccasionally 10% glucose infusion

CO and cyanideHigh flow oxygen then look it upCyanide ? Amyl nitrate, Sodium nitrite,

sodium thiosulphate (or dicobalt EDTA where available)

Questions?

Comments?

Suggestions?

chris.cresswell@wdhb.org.nz