Inhalation injury is the cause of most deaths from fires, especially house fires. Inhalation injury is found in 7-15% of hospitalized patients, but over 60% of hospital deaths from burns
Carbon Monoxide Poisoning
Carbon monoxide (CO) poisoning is caused by incomplete products of combustion, and occurs in patients who are trapped in a closed space with smoldering things around them. Symptoms may range from confusion to somnolence and coma. CO has an affinity for hemoglobin that is 200X that of oxygen. It is not a pulmonary toxin but causes its damage by rendering hemoglobin unable to transport oxygen.
Key things to know:
- Pulse oximetry is unreliable for detecting carbon monoxide poisoning; a blood gas with a carboxyhemoglobin is required.
- Treatment is 100% FiO2
- FiO2 of 1.0 reduces the half life of CO on hemoglobing from 2.5 hours to 40 minutes
- Begin empiric treatment with oxygen ASAP and continue for 6-12 hours/ until correction occurs of carboxyhemoglobin
- Role of hyperbaric oxygen remains controversial
Upper Airway Injury
Upper airway injury occurs due to a thermal burn to the face and/or neck, and is based upon swelling of the surrounding tissues; it can occur from non-flame injuries including scalds or chemical injury. Typical symptoms are hoarseness, stridor, and airway obstruction– and these are later symptoms.
Key thing to know:
- Edema is typically progressive over 24 hours following injury. Make sure to reevaluate patients who are of concern for upper airway injury regularly. Remember- if you are VERY concerned, it is safest to intubate.
Lower Airway (Pulmonary) Injury (“True” inhalation injury)
Pulmonary injury is a chemical injury to the tracheobronchial mucosa that evolves over the first few days post-burn. It is not ARDS, but it may mimic it clinically.
This injury results in the damage of the tracheal lining, loss of ciliary action, tracheal sloughing, bronchiectasis, air trapping, consolidation, and infection. It also facilitates multiple organ failure, which is the usual cause of death in these patients. Inhalation injury is present in more than 60% of hospital deaths from burns and is an independent risk factor for mortality in burn patients.
Key things to know:
- Symptoms may be absent for up to 72 hours after injury, then patients will develop hypoxemia and infection
- Diagnosis is confirmed with fiberoptic bronchoscopy
- Initial treatment is with humidified oxygen, and this is NOT an indication for prophylactic intubation
- Suspicion is a basis for early burn center referral