Inhalational injury

Today we discussed inhalational injury.

This is suggested by:
-soot in the upper airway, including mouth and nares
-singed eyebrows, nares
-persistent cough, stridor, wheezing
-hoarseness

Some principles of managment:
1) Consider early intubation; peak of airway edema is 48-72h after injury, and may make intubation extremely difficult. ARDS is also common following thermal injury
2) Look for carbon monoxide poisoning (more below)
3) Bronchoscopy should be performed initially then frequently to assess the extent of the injury and to clear sloughed airway epithelium
4) Look for cyanide poisoning (from plastics and fabrics burning). This presents as a triad of altered mental status, cardiovascular collapse, and lactic acidosis
5) Ophthalmology should see patients with inhalational injuries to exclude ocular injury, since they often go together

A few points about carbon monoxide poisoning:
Presentation
-Notoriously difficult to diagnose
-Common presenting symptoms are altered mental status, headache
-Physical exam may show a "cherry red hue" but this is unreliable

Labs
-Oxygen saturation is normal! (oximeter reads carboxygemoglobin as oxygen-bound)
-ABG tends to be normal (PO2 is dissolved oxygen, which is not changed by CO)
-Need to do co-oximetry on ABG sample to detect carboxyhemoglobin (reported as a percentage)

Management
-100% oxygen by non-rebreather mask for everyone (decreases the halflife of carboxyHgb from 300 to 100 min)
-Hyperbaric oxygen therapy decreases the halflife to 30 min. Generally recommended for any of 1) Carboxyhemoglobin level over 25% (although some sources suggest 4o%) 2) Signs of ongoing organ ischemia (lactic acidosis, myocardial ischemia, etc) 3) Loss of consciousness, 4) Pregnancy with a level over 20% or fetal distress

Links
Click here for a Cochrane review of hyperbaric oxygen in CO poisoning by Toronto investigators (including this hospital!)
Click here for a website from the University of Utah outlining burn management

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