TOXICOLOGY Notes with Complete
Solutions
- ANSWER-Dialysis x1
-Haemodialysis ( RRT as 2nd option ) for 6 hr then remeasure levels at 12hrs.
- ANSWER-Li-Tox risk factors
- ANSWER-Olanzipine
- Prolonged Qt is rare
-Extrapyramidal Sx uncmmon but can develop in upto 3 days post DC(same with
risperidone)
-Seizure -rare
-
- ANSWER-Rx of NMS- Also see my Notes
- ANSWER-withdrarwal -opiate
--------- - ANSWER-Indications of doing further IX
-Risk,(confirm./exclude)DDX,
-Poisoning.Complications,
-Antidote,
-Indication of elimination,
-Monitor
-Refine risk assessment or prognosis
Exclude or confirm an important differential diagnosis
Exclude or confirm an important specific poisoning
Exclude or confirm a complication that requires specific management
Establish an indication for antidote administration
Establish an indication for institution of enhanced elimination
Monitor response to therapy or define an end point for a therapeutic intervention
-ECG changes in Tox
1)Na ch Blockade e.g TCA
1)-Prolongation of PR and QRS intervals,
2)Right axis deviation of the terminal QRS as defined by
—Terminal R wave >3 mm in aVR-Pencil, point sign
—R/S ratio >0.7 in aVR.
,2) K Efflux blockade during repolarisation
-Prolonged QT
-Torsades De pontes
3) Na K ATPase inhibitor e.g Digoxin
-Increased automaticity
•Decreased AV node conduction
4)Ca Ch & B blockade
5) Hypo K,Mg & Ca --->prolonged QT
Hyperkalemia - ANSWER-Antipsychotics
TCA >10mg/kg
Olanzapine 40-100mg mod >300mg coma
Quetiapine >3g severe
Chlorprom >5g severe
-Intravenous digoxin begins to act in 15 to 30 minutes with a peak effect in 1 to 5 hours.
-Chronic toxicity - Get levels 6 hrs post intake(steady state) but levels don't corelate in
chronic toxicity.
Dig Toxicity
Additional measures in C arrest
-Lignocaine 1mg/Kg
-NaHCo3- 100 mmol + Insulin dextrose for Hyper K
-Atropine 0.6 mg aloquits
(james Hayes)
-Atropine ,Adrenaline with caution as myocardium is irritable as temporising measures.
-Cardioversion is also contraindicated ,if forced to use ,use smaller voltage - ANSWER-
Digoxin-Dig fab->Response is normally apparent by 20 minutes and maximal by 4
hours.
->Rarely, digoxin toxicity may recur beyond 24 hours and necessitate further
administration of digoxin immune Fab
End Points
->Restoration of normal cardiac rhythm and conduction
->Resolution of gastrointestinal symptoms
->Digoxin levels following treatment may appear very high as serum digoxin assays
measure both free and Fab-bound digoxin
-Dig levels unreliable in ingestion of natural alkaloids
,5/10/15 rule-->5 amp, K >5, 10 mg dose & conc 15 nmol/l
-Tox-Post intubation hyperventilation/Hyperventilate periinduction
-Aspirin toxicity
-TCA toxicity - ANSWER-Airway in Tox
Considerations
(Reversible, Complications, Complications of treatment, Shock, comorbidities)
•The reversibility of the poison - e.g. opioids
•Potential complications of the poison - e.g. strychnine
•Potential complications of likely treatment - e.g. whole bowel irrigation / activated
charcoal
•Presence of shock
•Comorbidities
Indications for airway protection
•These are less clear than for trauma, for the reasons stated above
A
-For airway protection from aspiration or treatment of aspiration
•GCS < 8
-mortality starts to increase when GCS < 8 following poisoning (although mortality risk is
lower in this group when ethanol is involved)
-however some patients with GCS < 8 can be safely managed without intubation if close
physiological monitoring is possible
•GCS > 7 and absent gag reflex
B
-Respiratory depression or apnoea
•For treatment of established aspiration pneumoniitis
C
•Haemodynamic instability
•The deteriorating patient with Na channel blocking toxicity
-intubate early to prevent acidosis developing
-apply therapeutic hyperventilation
Technique
•intubation should be by RSI
-attempted intubation using additional sedation alone is associated with much higher
rates of difficult intubation
•In poisoning with drugs that have sodium channel blocking toxicity
-Avoid suxamethonium
, -actively ventilate during induction
•insert NGT early after intubation
-especially if high aspiration risk
-if agents that delay gastric emptying ingested
-likely that charcoal or PEG likely to be administered
( up--------) - ANSWER-Cardiac arrest in Toxicity-Special RX
(-------) down
Lethal paediatric doses - ANSWER-Digoxin -4 mg (16 x250 mcg tablets)
Colchicine->0.5 mg/Kg- ( 10x0.5 mg tablets)
Iron->60 mg /kg elemental iron
Paracetamol - 200mg/Kg ( 4x500 mg tablets)
Sigle dose anticoagulant rodenticide.
Doses smaller than these are not dangerous for toddlers -assuming Weight <10 kg
(Enhanced Elimination)Substances adsorbable by activated charcoal
-50 g AC f/b 25 g PO every 2 hrs,
-Check Bowel sounds
-Stop If No BS or large NG aspirates ,Rarely required beyond 6 hrs. - ANSWER-(ABCD)
-MDAC decreases length of stay in ICU & duration of ventilation.
Aminophylline (theophylline) x
Barbiturates (phenobarbital)x
Carbamazepine x
Dapsone x( MDAC reduces severity of prolonged methaemaglobinemia)
Q-Quinine x
MDAC-Please deliver the charcoal quickly 'cos the victim's dying.
Phenobarbitone coma
Dapsone
Theopyhlline
Carbamazepine coma
Quinine
Colchicine
TCA
Valproate
Deathcap mushroom
(Enhanced Elimination)Toxins accessible to Hemodialysis x1
-if small molecule,
-small VOD,
-low protein binding,
-long elimination HL,
-low endogenous clearance
-Rapid redistribution from tissues
Solutions
- ANSWER-Dialysis x1
-Haemodialysis ( RRT as 2nd option ) for 6 hr then remeasure levels at 12hrs.
- ANSWER-Li-Tox risk factors
- ANSWER-Olanzipine
- Prolonged Qt is rare
-Extrapyramidal Sx uncmmon but can develop in upto 3 days post DC(same with
risperidone)
-Seizure -rare
-
- ANSWER-Rx of NMS- Also see my Notes
- ANSWER-withdrarwal -opiate
--------- - ANSWER-Indications of doing further IX
-Risk,(confirm./exclude)DDX,
-Poisoning.Complications,
-Antidote,
-Indication of elimination,
-Monitor
-Refine risk assessment or prognosis
Exclude or confirm an important differential diagnosis
Exclude or confirm an important specific poisoning
Exclude or confirm a complication that requires specific management
Establish an indication for antidote administration
Establish an indication for institution of enhanced elimination
Monitor response to therapy or define an end point for a therapeutic intervention
-ECG changes in Tox
1)Na ch Blockade e.g TCA
1)-Prolongation of PR and QRS intervals,
2)Right axis deviation of the terminal QRS as defined by
—Terminal R wave >3 mm in aVR-Pencil, point sign
—R/S ratio >0.7 in aVR.
,2) K Efflux blockade during repolarisation
-Prolonged QT
-Torsades De pontes
3) Na K ATPase inhibitor e.g Digoxin
-Increased automaticity
•Decreased AV node conduction
4)Ca Ch & B blockade
5) Hypo K,Mg & Ca --->prolonged QT
Hyperkalemia - ANSWER-Antipsychotics
TCA >10mg/kg
Olanzapine 40-100mg mod >300mg coma
Quetiapine >3g severe
Chlorprom >5g severe
-Intravenous digoxin begins to act in 15 to 30 minutes with a peak effect in 1 to 5 hours.
-Chronic toxicity - Get levels 6 hrs post intake(steady state) but levels don't corelate in
chronic toxicity.
Dig Toxicity
Additional measures in C arrest
-Lignocaine 1mg/Kg
-NaHCo3- 100 mmol + Insulin dextrose for Hyper K
-Atropine 0.6 mg aloquits
(james Hayes)
-Atropine ,Adrenaline with caution as myocardium is irritable as temporising measures.
-Cardioversion is also contraindicated ,if forced to use ,use smaller voltage - ANSWER-
Digoxin-Dig fab->Response is normally apparent by 20 minutes and maximal by 4
hours.
->Rarely, digoxin toxicity may recur beyond 24 hours and necessitate further
administration of digoxin immune Fab
End Points
->Restoration of normal cardiac rhythm and conduction
->Resolution of gastrointestinal symptoms
->Digoxin levels following treatment may appear very high as serum digoxin assays
measure both free and Fab-bound digoxin
-Dig levels unreliable in ingestion of natural alkaloids
,5/10/15 rule-->5 amp, K >5, 10 mg dose & conc 15 nmol/l
-Tox-Post intubation hyperventilation/Hyperventilate periinduction
-Aspirin toxicity
-TCA toxicity - ANSWER-Airway in Tox
Considerations
(Reversible, Complications, Complications of treatment, Shock, comorbidities)
•The reversibility of the poison - e.g. opioids
•Potential complications of the poison - e.g. strychnine
•Potential complications of likely treatment - e.g. whole bowel irrigation / activated
charcoal
•Presence of shock
•Comorbidities
Indications for airway protection
•These are less clear than for trauma, for the reasons stated above
A
-For airway protection from aspiration or treatment of aspiration
•GCS < 8
-mortality starts to increase when GCS < 8 following poisoning (although mortality risk is
lower in this group when ethanol is involved)
-however some patients with GCS < 8 can be safely managed without intubation if close
physiological monitoring is possible
•GCS > 7 and absent gag reflex
B
-Respiratory depression or apnoea
•For treatment of established aspiration pneumoniitis
C
•Haemodynamic instability
•The deteriorating patient with Na channel blocking toxicity
-intubate early to prevent acidosis developing
-apply therapeutic hyperventilation
Technique
•intubation should be by RSI
-attempted intubation using additional sedation alone is associated with much higher
rates of difficult intubation
•In poisoning with drugs that have sodium channel blocking toxicity
-Avoid suxamethonium
, -actively ventilate during induction
•insert NGT early after intubation
-especially if high aspiration risk
-if agents that delay gastric emptying ingested
-likely that charcoal or PEG likely to be administered
( up--------) - ANSWER-Cardiac arrest in Toxicity-Special RX
(-------) down
Lethal paediatric doses - ANSWER-Digoxin -4 mg (16 x250 mcg tablets)
Colchicine->0.5 mg/Kg- ( 10x0.5 mg tablets)
Iron->60 mg /kg elemental iron
Paracetamol - 200mg/Kg ( 4x500 mg tablets)
Sigle dose anticoagulant rodenticide.
Doses smaller than these are not dangerous for toddlers -assuming Weight <10 kg
(Enhanced Elimination)Substances adsorbable by activated charcoal
-50 g AC f/b 25 g PO every 2 hrs,
-Check Bowel sounds
-Stop If No BS or large NG aspirates ,Rarely required beyond 6 hrs. - ANSWER-(ABCD)
-MDAC decreases length of stay in ICU & duration of ventilation.
Aminophylline (theophylline) x
Barbiturates (phenobarbital)x
Carbamazepine x
Dapsone x( MDAC reduces severity of prolonged methaemaglobinemia)
Q-Quinine x
MDAC-Please deliver the charcoal quickly 'cos the victim's dying.
Phenobarbitone coma
Dapsone
Theopyhlline
Carbamazepine coma
Quinine
Colchicine
TCA
Valproate
Deathcap mushroom
(Enhanced Elimination)Toxins accessible to Hemodialysis x1
-if small molecule,
-small VOD,
-low protein binding,
-long elimination HL,
-low endogenous clearance
-Rapid redistribution from tissues
