Dangers of endotracheal intubation in salicylate poisoning

Q: Why is it advisable to avoid intubation as much as possible in a salicylate-toxic patient?

Answer: Intubation exacerbates the salicylate toxicity to unprecedented levels.

A salicylate-toxic patient may die very quickly if intubated just for precaution! They should be intubated -ONLY and ONLY - as a last resort, as if not intubated, they may die, or definitely need airway protection.

These patients have a high tendency to have peri-procedural cardiovascular collapse. Once a neuromuscular blocking agent (NMBA) terminates the salicylate-induced primary respiratory alkalosis, an acidosis acutely and substantially worsens, followed by salicylate anions protonating to uncharged salicylic acid, redistributing into vulnerable tissue, and exacerbating toxicity. On the other end of the spectrum, severe metabolic acidosis is considered a "physiologically difficult airway" because induction agents and NMBAs make the apneic phase of rapid sequence intubation physiologically intolerable. 

In situations where intubation is ABSOLUTELY NEEDED, many experts advise administration of 'one to two amps of bicarb.' Another option is to do awake intubation without NMBA to avoid an apneic period. In such cases, Ketamine is a good choice because it maintains respiratory drive. If NMBA is administered, the apneic time should be minimized.

After intubation, high minute ventilation (MV) should be maintained to counter severe acidosis expected post-intubation in salicylate poisoning. The rule of thumb is to apply the same MV as the patients had before intubation. Again, it is advisable to avoid long-acting NMBAs.

The eventual goal is to take control of acid-base balance via more definitive treatment, such as hemodialysis or CRRT.

#toxicology

#procedures

#acid-base

References:

1. Stolbach AI, Hoffman RS, Nelson LS. Mechanical ventilation was associated with acidemia in a case series of salicylate-poisoned patients. Acad Emerg Med 2008; 15:866.

2. Greenberg MI, Hendrickson RG, Hofman M. Deleterious effects of endotracheal intubation in salicylate poisoning. Ann Emerg Med 2003; 41:583.