Toxicology Flashcards
What are the main clinical features of large acute lithium OD
mainly GI - nausea, vomiting, and pain and diarrhoea
under 25g mild
over 25 mod to severe
neurotox rare
What are the main clinical features of chronic lithium toxicity
Neurotoxic:
Grade 1 = tremor, agitation, hyper-reflexia, ataxia
* Grade 2 = stupor, rigidity, hypotension
* Grade 3 = coma, seizures, myoclonus
name three factors that predispose to chronic lithium toxicity
impaired kidney function
diabetis insipidus
dehydration
sodium depletion
drug interactions eg NSAIDS
What is the modality for lithium enhanced elimination?
What are the indications?
haemodyalsis
Indications;
renal impairement
serum lithium >2.5
established neurotoxicity
What agents may increase chance of heat stroke?
What are the methods for rapidly cooling?
MDMA
diuretics
salicylates
anticholinergic agents
Cooling:
Evaporative cooling eg spray and fan
ice packs to groin an axilla
arctic sun
list some conditions and clinical findings linked to alcohol abuse
- Acute alcohol withdrawal – tremor, tachycardia, fever, seizures
- Wernicke’s encephalopathy – nystagmus, confusion, ataxia
- Peripheral neuropathy – stocking style sensory loss, loss ankle jerk
- Cerebellar degeneration – dysdiadochokinesis, nystagmus, ataxia, past pointing etc
- Several others OK eg alcoholic hepatitis, pancreatitis, gastritis
what is the toxic dose of amitryptiline?
over 10mg/kg life threatening
what are the toxic effects of anticholinergics
what is the key investigations in TCA overdose
**ECG **
to look for QRS widening due to sodium channel blockade
* QRS over 100 seizures
* QRS over 160 VT
Other
paracetamol
VBG
renal function
how do you treat a TCA overdose seizure with end points
- sodium bicarb 8.4% 1-2ml/kg IV, until seizure stops or qrs under 100 then midazolam to terminate seizure
- Check ECG - if QRS widening for 8.4% sodium bicarb to reduce QRS
- early intubation to avoid coma due to respiratory acidosis - mention drugs
- settings - tv 6-8ml/kg, hyperventilate 7.5-7.55, PEEP 5
- fluids
- activated charcoal if large ingestion
what is the toxic dose of two main calcium channer blocks
What is the mechanism of toxicity?
Verapamil and diltizaem both over 10 tablets. 1 or 2 in children
Mechanism
- vasodilates and negatively ionotropic and chronotropic by stopping opening of L type calcium channels decreasing cellular contractility
- Also impairs insulin release
management steps for calcium channel blocker OD causing significant brady cardia
- ABCDE
- IF fluid boluses
- 10-20ml boluses of calcium cl
- adrenaline or noradrenaline
- high does insulin dextrose - bolus 50ml 50% dextrose plus 0.5-1 unit/kg - then infusion
- monitor BSL and mg and K
why insulin dextrose in calcium channel blocker OD
overcomes metabolic starvation in the heart to increase output
diagnosis and pathophysiology
acute management?
Methaemoglobinaemia
fe2 changes to fe3 so haemaglobin becomes methaaemoglobin
reduces oxygen carrying capacity and does not give up what it has
Management
o2 via NRM
remove causatie agent
methyline blue 1mg/kg iver 5 mins with repeated doses if needed
what agents can cause Methaemoglobinaemia
prilocaine
dapsone
chlroquine
GTN
what factors can increase chance of toxicity with calcium channel blockers
agent - verap and dilt the worst
dose
co-ingestion other cardiac meds
extremes of age
co-morbitidies
features of calcium channel toxicity
bradycardia
hypotension
hyperglycaema
pulmonary oedema
lactic acidosis
seizures
what is the lethal dose of digoxin?
over 10 mg in adult
4mg in child
Over 10x daily dose
what are the features of acute dig toxicity
**GI **- nausea and vomiting
**CNS **- lethargy, confusion, delirium
**CVS **- bradycardia, heart blocks, slow AF, VT, SVT
what are the indications for digibind?
What is the dose
Indications
* cardiac arrest
* life threatening arythymia
* lethal dose (over 10mg adult and 4mg child)
* K over 5.5
* dig level over 15
FIVE TEN FIFTEEN
Dose
5 or 10 ampoules
what are the clinical effects of eucalyptus oil ingestion?
CNS depression - LOC/seizures
**Respiratory **- aspiration and aspiration pnemonitis, cough, choking
**GI **upset - nausea and vomiting and oral irritation
**CVS **- tachy and hypotension
what is the management of eucalyptus oil ingestion?
- supportive care - intubate and ventilate to protect aiway as needed
- observe
- monitor electrolytes and BP
- consult tox
- admit
- no role for antidoes or decontamination
What are the key things in a tox risk assessment
- agent
- dose
- co-ingestion
- time of ingestion
- co-morbidities
- clinical features
**infections **- meningitis/encephalitis
**toxidrome **- serotonin syndrome, anti cholinergic syndrome, NMS, sympathomimentic toxicity
**endocrine **- thyroid storm
enviromental- heat stroke
delirium tremens
**CNS **- stroke
What is the Hunter Serotonin toxicity Criteria?
must have a seritonergic agent in their system plus at least one of the following;
- spontenous clonus
- inducible clonus and agitation/diaphoresis
- ocular clonus and agitation/diaphroresis
- tremor and hypereflexia
- tremor and hypertonia
relevant features of history post insulin overdose and how it is relevant to management
- type of insulin - will affect duration of toxicity and observation
- amount - severity of toxicity
- multiple sites or one site - one site longer duration of action
- diabetic or not - dictates how you ween glucose infusion
for insulin OD what are the treatments
IV dextrose infusion aiming BSL over 3.5
IV K aim for normal range
10-50%dextrose
what are three methods of decontamination used in iron OD and when they would be used
- WBI if over 60mg/kg
- Gastric lavage via ETT and witing 90 mins ingestion
- surgical or endoscopic removal over 120mg/kg
what is the drug and dose for iron chellation?
Desferrioxamine IV. 15-40 mg/kg/hr
iron overdose, List two relevant findings and how it may alter management
RUZ consildation with no evidence of iron in GI tract
no need for WBI - may need bronc
what bloods may you order in suspected iron OD
serum iron levels 4-6 hours post
VBG for lactate and acid base disturbance
coags - liver involvement
BSL - hypo or hyperglycaemia
U+E - renal involvement
FBC - leucocytosis or thrombocytopenia
common agents for QT prolongation
The anti
Antibiotics - cipro, clarithro
Antidepressants - SSRI, TCA, lithium
antipsychotics - haloperidol, chlorpromazine
antihistamines - loratidine
Examination features of serotonergic toxidrome
main features
What illicit drugs can cause this?
Treatment?
widespread st elevation
narrow complex tachy
depression avr
Drugs
* sympathomimetic eg cocaine, ecstasy
* LSD
* volatile agents
Treatment
IV benzos
calm environment
GTN infusion
?thorombolytics
what underlying condition can predispose you to methaglobulinaemia
G6PD
what is the dose of activated charcoal
50g
1g/kg in paeds
what are the contraindications for activated charcoal
active resus
aspiration risk
charcoal wont bind eg metal
benign agent
sub toxic dose
too long since ingestion
what are the features of significant carbamazepine overdose
anti cholinergic effects
CNS - LOC, seizure, ataxia, nystagmus
CVS - hypotension, tachy or brady arrthymia, prolonged PR, QRS, QT
With any drug related seizure, wht should be ruled out?
hypoglycaemia
eclampsia
infection
hyponaetramia
co-ingestion
ICH
propanolol
life threatening effects of OD and the management
- Coma - airway protection
- seizures - benzos
- brady/hypotension - atropine, adrenaline, noradrenaline
- sodium channel blockade - bicarb
OD low GCS
ECG findings
what drugs tend to do this?
broad QRS
RAD
prolonged QT
TCA
list the abnormalities and reason why
What is the most likely clinical scenario
Severe hyperkalaemia – cellular shift due to metabolic acidosis, renal failure, cell death with rhabdo
High anion gap metabolic acidosis – renal failure, lactic acidosis lost likely
Renal failure – urea/creat less than 100 – suggests intrinsic renal failure – most likely due to rhabdo
scenario - rhabdo from long period on floor post sedation
is there a role for decontamination in liquid paracetamol?
what is the threshold for liquid paracetamol and when should you measure level?
no - absorption is too quick
200mg/kg of liquid - 2 hours
what are the one pill killers for kids?
verpamil
diltiazem
sodium channel blocks eg TCA
opiates
gliclazide
theophylline
what are the steps when someone gets an anaphylactoid rash with NAC
stop
bronchodilator if wheezy
anti histmiane
pred 1mg/kg
start at slower rate
what are the indications for activated charcoal in paracetamol OD
within 2 hours for immediate release
within 4 hours for sustained release
massive (over 30gm) within 24 hours
what is the criteria for cessation of NAC
if non toxic - repeat paracetmol below line and falling
if toxic - NAC complete and ALT less than 50 and paracetamol less than 10
what are the criteria for transfer to liver unit post paracetamol OD
INR > 3.0 at 48 hours or > 4.5 at any time
* oliguria or creatinine > 200 mmol/L
* persistent acidosis (pH < 7.3) or arterial lactate > 3 mmol/L
* systolic hypotension with BP <80 mmHg, despite resuscitation
* hypoglycaemia
* severe thrombocytopenia
* encephalopathy of any degree, or ALOC (GCS < 15) in the absence of sedatives
what is a terminal R wave in v3 suggetive of?
TCA overdose
- Taken multiple serotonergic medications – risk of serotonin syndrome
- Multiple medications that may cause sedation – ALOC/need for airway protection
- tCA overdose >30mg/kg – associated with severe toxicity
- Paracetamol potential toxic dose ie >10g, or >150mg/kg
risk assessment
large ingestion of lethal agent
GCS already 14
alreasy showing biochemical signs
what are the decontamination methods for K OD
Pro and con for each
WBI - good because quikcer then dialysing, hard becuase need intubation and staff to manage this
dialysis - good because definitive but invasise
differentials for methaglobulinaemia with prilocane
what is definitive test?
treatment options
anaphylaxis
seizure
VT
Test - ABG for saturation gap - pa02 v sats
methyline blue
high flow o2
HBOT
vitamin C
NAC
HAGMA with respiratory alkalosis
WINTERS = Expected Co2 = 1.5 x HCO3 +8 +/-2
what blood gas features are most consistent with toxic alcohol ingestion?
high lactate
high osmolar gap
high anion gap
what are the important investigations with ?toxic alcohol ingestion and why
what are the treatments for toxic alcohol overdose
what are the clinical features of salicylate toxicity?
- initial hyperventilation
- tinnitus
- nausea
- vimiting
- dehydration
- pyrexia
- confusion
- dehydration
for salicylate OD
what drugs can be used to manage serotonin syndrome
benzos
serotonin agonists - olanzapine, chlorpromazine
drugs that cause serotonin syndrome
Antidepressants:
MAOIs - any
SSRIs - any
SNRIs - any
TCAs - any
Opioids – tramadol, buprenorphine
Anticonvulsants (Valproate, Carbamazepine)
5-HT3 antagonists - ondansetron
Metoclopramide
Lithium
Amphetamines
Antibiotics – ciprofloxacin, erythromycin
what conditions need to be met to remove snakebite pressure bandage
No clinical signs of envenoming
No lab signs of envenoming
Patient in monitored, witnessed area
Local access to antivenom
description
What is it?
What snakes can cause this?
ptosis
pupil down and out
third nerve palsy
death adder
tiger
taipan
Low GCS
interpret and list tox causes
HAGMA
Causes
Cyanide
o Isoniazid, Iron
o Alcohol (ethylene glycol, methanol, propylene glycol)
o Salicylates
o Valproate
o Paraldehyde
what are the signs and symptoms of cyanide toxicity
treatment for cyanide toxicity
what paralytic is unsafe in hyperthermic patient?
sux
unresponsive after femoral nerve block with bupivicanine
What do you do?
what are specific antidotes?
stop injection
begin CPR as per aLS
support airway and oxygenate
antidotes
intralipid 20% 1-1.5ml/kg every 3 minutes then infusion
causes of tachycardia post intubation and historical feature
four important complications of GHB overdose
coma
agitation
fluctuation consciouness
hypotension
aspiration
secondary injuries
what are the indications for intubation with GHB
- cant maintain away
- hypoventilation
- extreme agitaiton
- resp failure
- aspiraiton
- concern for head injury
why may ETc02 be high after intubating?
1) Increased CO2 production – fever, thyrotoxicosis
2) Increased pulmonary perfusion – High CO, hypertension
3) Poor alveolar ventilation – hypoventilation, bronchial intubation
4) Technical mechanical errors – leak or faulty valve
key in benztropine OD
no sweating
features of meth intoxication
Agitation/Anxiety/ Hypervigilence
Paranoia/Hallucinations
Psychomotor agitation – restlessness, tremor
Pressured speech
Sweating, flushed skin
Teeth Grinding, Jaw clenching
Mydriasis
Hypertension
Tachycardia
what are the indications for haemodialysis in toxic alcohol ingestion
large ingestion with osmolar gap over 10
PH less than 7.3
renal failure
clinical deterioration
dose dependant clinical features of olanzapine OD
Quetiapine:
Lethal dose
Effects
treatment
- over 3 g
- anticholinergic, plus coma and hypotension
Histamine receptor blockade - benzos for agintation, intubation for coma, fluids and norad (not adrenaline) for hypotension
NO ADREANLINE
What are the symptoms of cholinergic syndrome and what causes it?
treatment
increased parasympathetic
organophosphates, physostigmine, sarin
benzos for seizures, atropine 0.02mg/kg pr pralidoxime and double dose 3-5 mins
Mental status, eyes, lungs, obs, bowel sounds, bladder and neuro for:
Sympathomimetic/gaba withdrawal
Cholinergic
Anticholinergics
Opiod withdrawal
NMS
serotonin syndrome
How does fomepizole or alcohol work in methanol poisoning
Symptoms toxic alcohol poisoning
SS v NMS
salicylate dangerous dose
over 150 - sx
over 300 severe
decontamination of hydrofluric acid
indications endoscopy
nothing to eat and drink - remove clothing and flush eyes with saline
endoscopy - abdo pain or GI features eg haematemsis, vomiting
nac dose
200 mg/kg over 4 hours
100 mg/kg over the next 16 hours
100% hydroflouric acid - what level causes systemic
investigations and signs of tox
antidote
over 2.5% - hydrogen ions bind to calcium causing cellular damage - seizure possible
Ix
Ca/Mg/K - hypocal/Mg and high K
ECG - prolonged QT interval
**antidote - **
* calcium gluconate IV 10% - 60mmol
* topical calcium gluconate 2.5%
* s/c mix with normal saline
* nebulised for inhalation
what electrolye abnormality is mdma linked to and why
Na - SIADH/polydipsia
toxic dose panadol over 48 hours?
anything over normal dose (4g/day)
when would you just start NAC
over 10g
200mg/kg
