Toxicology/Pharmacology

Question 1

Hyperthermia

Answer 1

Fever - resetting hypothalamus due to cytokines

Hyperthermia - temp > 37.5 with normal hypothalamic set point - imbalance of heat production and loss

Hyperpyrexia - temp >41

Question 2

Hyperthermia causes

Answer 2

Environmental - exertional and non-exertional heat stroke
Endocrine - hyperthyroid, phaeo
Drug - NMS, Serotonin syndrome, Malignant hyperpyrexia, MDMA/cocaine/ampetamines

Question 3

MH

Answer 3

Rare, AD, variable penetrance
Ryanodine receptor - excessive Ca release causing sustained muscle contraction

S&S: muscle rigidity, met and resp acidosis, increase O2 comsumption, heat prod.

Mx:
1 - Recongition
2 - Immediate - help, remove agent, hyperventilate with 100% O2, use non-dep NMB
3 - Treatment - Dantrolene, treat high K, acidosis, DIC, arrhythmias
4 - Monitor - ICU, AKI, genetic counselling

Question 4

NMS

Answer 4

Idiosyncratic reaction to antipsychotics (haloperidol, prochlorperazine)

Insidious onset over week or so with altered mental status, autonomic disturbance, pyrexia and muscle rigidity (extrapyramidal signs)

Mx - withdrawal, bromocriptine, dantrolene

Question 5

Serotonin Syndrome

Answer 5

Caused by: 
Serotonin agonists: LSD, pethidine breakdown 
Increase serotonin activity: MDMA
Prevention of reuptake: SSRIs, Tramadol
Prevention of breakdown: MAOi

Rapid onset: altered mental status, autonomic disturbance (fever) and neuromuscular excitability (tremor, clonus)

Mx: withdrawal, benzos, propanolol, dantrolene

Question 6

Heat Stoke

Answer 6

Altered mental status, anhydrosis and temp >40.6

Non-exertional and exertional

Question 7

LA toxicity

Answer 7

0.25% = 2.5mg/ml, 1% = 10mg/ml
Bupivacaine max dose 2mg/kg

Clinical:
1 - Neuro - paraesthesia, visual/auditory disturbance, agitation, seizures, LOC
2 - CVS - blocks fast Na channels - long PR, QRS widening, long QT - VT/arrest
3 - Vascular - low conc cause vasoconstriction, at high conc cause vasodilation

Mx:
ABCDE
Benzos for seizures
Intralipid
Sodium bicarbonate

Question 8

Paracetamol OD

Answer 8

Kings criteria:

PH < 7.3 after resus
Or all 3 of: INR >6.5, Creat >300, enceph 3 or 4

Question 9

PRIS

Answer 9

Metabolic acidosis and cardiac dysfunction, mainly bradycardia.
Plus one of:
 1 - Rhabdo
 2 - High triglycerides
 3 - Renal failure

Impaired mitochondrial fatty acid metabolism leading to mitochondrial dysfunction, decreased oxygen use, anaerobic respiration and lactate production. Cardiac and skeletal muscle ischaemia and necrosis.

RF:
High dose, young age, brain injury, Low carb/high fat intake (TPN), high catecholamine levels (sepsis), high steroid levels, hypoxia

Mx:
Stop
Alternative
Treat rhabdo
Treat cardiac issues
RRT
Ensure carbohydrate intake
ECMO