This is a quick guide to inhalation injury. I’ll review what YOU can do as a PCP if you suspect inhalation injury, how to identify it, as well as what I do in my specialty. For information regarding burns in general or when to refer to a burn center, please see my post about burn center referrals. Keep in mind, inhalation injury is the most common immediate cause of death in a large burn patient and should ALWAYS be on your differential in patients coming from a fire in an enclosed space. Be prepared, I’ll probably say that like 100 times.
More common in the elderly, immobile, and children
Fire in an ENCLOSED space
Facial burns (2nd degree or worse)
Alcohol and drug use + fire
Inhalation injury can be devastating for 2 very important reasons
Smoke and inhaled irritants cause airway edema and mucosal sloughing, leading to loss of a patent airway.
Burning things creates poisons which can be inhaled and kill you.
Organic things combust into carbon which is carcinogenic and an airway irritant. Synthetic things often combust into hydrogen cyanide. This can be inhaled as well and cause cyanide poisoning. Annnd then of course there is carbon monoxide.
Hydrogen Cyanide poisoning - colorless gas with the smell of bitter almonds. Cyanide kills people because it impairs oxidative phosphorylation. It impairs a cell’s ability to utilize oxygen and produce ATP.
Carbon monoxide poisoning - colorless and odorless gas. CO kills people because it has 200 x the binding affinity to hemoglobin as oxygen does. CO that binds prevents O2 from binding. However, this also means that remaining O2 on the hemoglobin will bind more tightly to the hemoglobin molecule and will not be delivered to the tissues.
Inhalation injuries do NOT occur just because someone has a burn to the face. In fact, they are RARE when a fire has taken place out doors (campfires, brush fires, etc).
Suspect inhalation injury in any patient coming from a house/building fire or a car fire. Essentially, any enclosed space.
Syncope + a house fire? Higher index of suspicion
Does your patient smoke? Do they have existing lung disease? Have a higher index of suspicion.
Was extrication from the fire prolonged?
Kids are at a high risk because they tend to hide in closets during a fire rather than escape. The elderly or immobile have physical barriers to escape.
#1: If the history supports possible injury and the patient has a change in voice/declining respiratory status, INTUBATE THEM. You will NEVER be at fault for protecting an airway.
If you suspect CO poisoning, make sure the patient is on FiO2 of 100%
If your facility is able, get the following labs: BMP, ABG, carboxyhgb
If you have high index of suspicion and are able, administer hydroxycobalamin to reverse cyanide toxicity - be aware, this will turn their urine maroon like red wine. Do not be alarmed.
If you have ANY suspicion of inhalation injury, they must be sent to a local burn center.
REMEMBER: SpO2 saturations CANNOT tell you if someone has CO poisoning. This is because a pulse oximeter is only measuring binding affinity of oxygen to hemoglobin, not the amount of oxygen present in the tissues. Someone can have CO poisoning and have normal SpO2. Only a carboxyhemoglobin (and a good physical exam) can tell you if CO poisoning has occurred. I would like to point out that the stereotypical “cherry red skin” appearance of CO poisoning is NOT often reliable. This is particularly the case in a burn patient whose burns alone will cloud your ability to determine this.
If we suspect cyanide poisoning and hydroxycobalamin hasn’t been administered, we will do that. If we have a patient with moderate to severe CO poisoning, we will send them for hyperbaric oxygen therapy. We will usually do 1 to 3 dives at 2 atm for 2 hours each to help offload the CO. The theory here is that you expose the patient to higher atmospheric pressure and 100% FiO2 to force the CO off of the hemoglobin.
Most patients with suspected inhalation injury are (thankfully) intubated by the time they arrive to our burn unit. The first thing we do is bronchoscopy to confirm inhalation and categorize it. We grade inhalation injury using the AIS - Abbreviated Injury Score:
Grade 1 - mild injury - minor or patchy areas of erythema/carbonaceous deposits
Grade 2 - moderate injury - larger areas of erythema, carbonaceous sputum, bronchorrhea, or partial obstruction
Grade 3 - severe injury - severe inflammation of the airway with friability, copious carbonaceous deposits and areas of partial/full obstruction
Grade 4 - massive injury - evidence of mucosal sloughing, necrosis, and endoluminal obliteration
Patients with a grade 0 or 1 injury will likely be extubated a couple of hours later if they are otherwise healthy. Sometimes, we keep patients with existing lung disease on the vent with a grade 1 so that we can give aggressive suctioning and medications to optimize their vent wean.
Anyone with a grade 2 or high will likely take longer to extubate, at least 24 hours - more than that if the injury is worse or if they have existing lung disease. Smokers tend to suffer much more than people with health lungs, as do asthma and COPD pts.
We have an inhalation protocol for our ventilated patients which consists of the following:
Heparin 5,000 U inhaled solution Q4h x 7 days
Mucomyst 3 mL inhaled solution Q4h x 7 days
Albuterol 2.5 mg inhaled solution Q4h x 7 days
We give albuterol and mucomyst together and alternate with the heparin so that the patient is receiving treatment every 2 hours. We do this to help flush out toxins, open the airway, and breakup/thin out blood clots (hence the heparin). Bad inhalation injuries will have bronchial bleeding and heparin helps remove and prevent further blood clots from clogging up the bronchi.
From here, we wean patients off the vent! If a patient needs a vent for > 1 week or has had failure to wean for a variety of reasons, we will usually give them a tracheostomy.
