Salicylates

Question 1

After therapeutic dosing with ASA max serum concentrations occur at what time?

Answer 1

1hr

Question 2

In overdose, peak serum concentrations occur when?

Answer 2

4-6hr

Question 3

Normally, salicylate is in a charged form in physiologic pH. What happens when free salicylate levels rise?

Answer 3

Acidosis, then salicylate is mostly in its uncharged form and can travel across cell membranes.

Question 4

What order kinetics does salicylate follow?

Answer 4

First

Question 5

Half life of salicylate:

Answer 5

2-4hr

Question 6

What causes the initial respiratory alkalosis seen in ASA overdose?

Answer 6

Direct stimulation of the medulla -> tachypnea, hyperpnea

Question 7

Children develop a large respiratory alkalosis in ASA overdose (T/F):

Answer 7

F. They don’t breathe that deeply, they may be profoundly acidemic before they look sick.

Question 8

Three things contributing to the anion gap metabolic acidosis seen in ASA overdose:

Answer 8

Impaired renal function (accumulation of acids)
Interference with Krebs cycle (pyruvic and lactic acids build)
Uncoupling of oxidative phosphorylation

Question 9

After what dose of ASA ingested should someone be recommended to come to the ED?

Answer 9

> 150mg/kg

Question 10

Things to order in salicylate OD:

Answer 10

Lytes, calculate anion gap
K
BUN/creatinine
glucose
serum salicylate on presentation and q1hr if sick
Urine ketones, glucose, pH, spec grav

Question 11

Preferred method for GI decontamination of ASA overdose:

Answer 11

MDAC, 2-4 doses

If early presenter or massive OD consider gastric emptying

Question 12

Rule for pediatric fluid resuscitation?

Answer 12

4-2-1 (4cc/kg for the first 10kg, then 2cc/kg for the next 10kg, then 1cc/kg over 20kg)

Question 13

Airway considerations in ASA overdose (3):

Answer 13

Avoid it if you can
Do it awake if you can’t
Bolus bicarb 2mEq/kg to help with acidosis/arrest

Question 14

Plasma / urine alkalinization strategy in ASA overdose:

Answer 14

Keep salicylic acid ionized and prevent passive tubular resorption.
Bolus 1-2mEq/kg IV
Bicarb infusion at 2x maintenance: 1L D5W + 3 amps + 40mEq KCl

Question 15

Method of extracoporeal removal for ASA overdose:

Answer 15

HD or CVVHD

Question 16

Indications for HD in ASA overdose:

Answer 16

pH < 7.2
end-organ dysfunction (AMS, acute lung injury, coagulopathy)
inability to tolerate fluid load for alkalinztion
renal failure
absolute acute serum concentration >100
absolute chronic serum concentration >60