Aspirin overdose

Question 1

What ABG abnormality is seen in aspirin poisoning?

Answer 1

Mixed - metabolic acidosis with respiratory alkalosis

Question 2

What is the anion gap in aspirin overdose?

Answer 2

Increased - although in some analysers salicylate ion is mis-detected as Cl-, pseudonormalising AG

Question 3

What are the mild/mod/severe levels for aspirin overdose?

Answer 3

Mild - <150mg/kg OR level <300mg/L
Mod - 150-300mg/kg OR >700mg/L
Severe - 300-500mg/kg OR >700mg/L

Question 4

What clinical features are associated with mild aspirin poisoning?

Answer 4

nausea
vomiting
dizziness
bounding pulses

Question 5

What clinical features are associated with moderate aspirin poisoning?

Answer 5

headache
confusion
tinnitus
hyperventilation
fever
tachycardia

Question 6

What clinical features are associated with severe aspirin poisoning?

Answer 6

hallucinations
convulsions
coma
respiratory arrest due to flash pulm oedema

Question 7

What should be avoided in aspirin poisoning?

Answer 7

Avoid intubation unless there is evidence of respiratory failure (worsening respiratory acidosis, severe hypoxemia). Loss of hyperventilatory drive can result in sudden decompensation and death.

Question 8

What is an important part of management of aspirin poisoning if salicylate levels continue to rise?

Answer 8

Gastric decontamination

• charcoal within 1hr OR again if levels continue to rise
• gastric lavage if 500mg/kg or more

Question 9

How often should you repeat plasma salicylate levels in aspirin overdose?

Answer 9

Every 2hrs - it may take a while for salicylate levels to rise

Also check ABG, FBC, U&E, INR

Question 10

When can you consider discharge in aspirin overdose?

Answer 10

• asymptomatic patients with normal acid-base status
• after observation for 6 hours
• provided their plasma salicylate concentration is below 300 mg/L (2.2 mmol/L).

Question 11

What electrolyte needs to be corrected in aspirin overdose?

Answer 11

Hypokalaemia
Needs to be treated urgently – low potassium increases risk of pulmonary oedema but also normal/high K+ is needed for further therapy

Question 12

What treatment option helps salicylate excretion?

Answer 12

Sodium bicarbonate infusion 8.4%
- this alkalinises urine promoting salicylate excretion

Question 13

What treatment should be considered in salicylate levels >900mg/L or >700mg/L?

Answer 13

CVVHDF

Also indicated in children and those >70yrs who are high risk from overdose. Also if severe acidosis, pulm oedema, coma or renal failure.

* Continuous venovenous hemodiafiltration = CVVHDF

Question 14

How is pulmonary oedema in aspirin overdose managed?

Answer 14

NIV

Question 15

Which of the following is false in salicylate poisoning?
* A initial blood gas may show respiratory alkalosis only
* B severe toxicity is an indication for haemodialysis
* C Salicylate levels are useful in management of overdose
* D anion gap is normal
* E Gastric lavage is useful

Answer 15

D

Question 16

What do the CXR and ABG show?
* A Bilateral pneumonia and respiratory alkalosis
* B Pulmonary oedema and respiratory alkalosis
* C Bilateral pneumonia and compensated metabolic acidosis
* D Pulmonary oedema and compensated metabolic acidosis
* E Pulmonary oedema and profound metabolic acidosis

Answer 16

C

Question 17

What investigations should be done in overdose in general?

Answer 17

Question 18

What is the calculation for anion gap?

Answer 18

(Na + K) - (Cl+HCO3)
Normal range 16+/- mEq/L

Question 19

Define toxidrome.

Answer 19

constellation of symptoms specific to a poisoning syndrome
predictable by the pharmaceutical action of the toxin