poisoning Flashcards
paracetamol overdose - toxic dose
single ingestion of 150-250 mg/kg may be hepatotoxic
risk of toxicity higher if concomitant regular use of:
alcohol
phenytoin
carbamazepine
presentation of paracetamol overdose
often asymptomatic
vomiting
abdo pain / tenderness
deferred complications (24-72h):
acute liver failure, GI haemorrhage, cerebral oedema acute renal failure pancreatitis
Validated prognostic indicator in paracetamol overdose
plasma paracetamol conc over the treatment line on plasma conc vs time (hours) graph
PARACETAMOL OVERDOSE: MANAGEMENT
clinical assessment
paracetamol / salicylate level, INR, U/E, creat, LFTs, ABGs
Start IV n-acetylcysteine
if presentation < 1h: give 50g activated charcoal
if presentation > 24h: give NAC to all severe or high risk OD
daily LFTs, INR
Most common outcome is no liver damage and patients are treated and discharged medically after 24 hours
consult with liver unit early in severe OD where transplantation is
a possibility
use of acetylcysteine to treat paracetamol overdose
given by IV infusion in 5% glucose or 0.9% NaCl.
3 consequtive IV infusions to be given sequentially with no break between them. a total of 300mg/kg body weight over a 21 hour period.
adults - weigh the PT to get the correct dosage band. use the dosing table to determine the amount needed in each of the 3 periods.
1st = 200ml infusion over 1hr
2nd= 500ml infusion fluid over 4 hours
3rd = 1 litre of infusion over 16hours.
MARKERS OF HIGH RISK OF SUICIDAL
INTENT
middle-aged /elderly male
widowed / divorced / separated
unemployed
chronic illness
alcohol or drug abuse
planned
suicide note
attempt to evade discovery
signs and symptoms of a tricyclic overdose
Coma (late)
Pyramidal signs
INO
Seizures
tachycardia
wide QRS
prolonged QT
VF
Anticholinergic side effects dry mouth blurred vision urinary retention hallucination
management of tricyclic overdose
management
charcoal 50g
lavage within 1h if > 750mg
monitor:
ITU for severe OD
ECG (QRS prolongation)
SaO2
ABGs (acidosis)
treat arrhythmias conservatively
use phenytoin if no response
treat seizures with diazepam
poisoning causes of metabolic acidosis
paracetamol
salicylates
tricyclics
ethanol
Aspirin poisoning symptoms and signs
tinnitus
hyperventilation
sweating
non-cardiogenic pulmonary
oedema
respiratory alkalosis
metabolic acidosis
hypoglycaemia
hypokalemia
if level > 75mg/dl
(5.4 mmol/l):
confusion
delirium
cardiac arrest
Aspirin poisoning: management
Aspirin poisoning: management
charcoal 50-100g remeasure salicylate 2-3h later
monitor ABGs, glucose
look out for pulm.oedema
then based on salicylate level:
< 4.3mmol/l: increase fluid intake monitor
> 4.3 mmol/l < 5.1 mmol/L
alkalinisation of urine (to pH8)
> 5.1 mmol/L - dialysis
opiate overdose symptoms
sedation/coma pin point pupils resp depression cyanosis needle tracks endocarditis DVT
opiate overdose management
management
airway, breathing
iv access and naloxone
if response consider
infusion
CXR ? aspiration
U/E creat
CK (?rhabdomyolysis)
Hyponatraemia in MDMA overdose
Uncommon but well publicised
MDMA induces vasopressin release
(Lancet 1998; 351: 1784)
Excessive water drinking contributes
Neurological features due to dilutional hyponatraemia and cerebral oedema
Water restriction is mainstay of treatment
Digoxin poisoning: management
Oral activated charcoal
Correction of low Mg and low K but not hyperkalaemia
Correction of volume depletion
ECG monitoring and temporary pacing
Indications for Digoxin Fab:
VT, VF, 3rd degree HB K > 6mmol/L Digoxin > 7.8ng/mL (10nmol/L) 6h post OD
