Barotrauma

The protocol for Barotrauma:

Barotrauma

 

Let’s break it down!

The term “barotrauma” simply refers to any physical damage to body tissues caused by a difference in pressure between a gas space inside, or contact with, the body, and the surrounding gas or fluid. This is likely to occur any time someone is exposed to a significant change in ambient pressure, such as in scuba diving, explosive blast waves, and even aggressive mechanical ventilation. The areas of the body that are most affected by pressure changes are hollow organs, such as the lungs, ears, and sinuses.  We’ll break them each down one by one:

Pulmonary Barotrauma

Also known as “pulmonary over-inflation syndrome“, and it’s the second leading cause of death among scuba divers, behind drowning. It is most commonly caused during breath-holding on ascent from scuba diving. The compressed gas in the lungs expands as the ambient pressure decreases causing the lungs to over-expand and rupture unless the diver allows the gas to escape by maintaining an open airway, as in normal breathing. The lungs do not sense pain when over-expanded, giving the diver little warning to prevent the injury. 

These injuries can manifest themselves as a pneumothorax or subcutaneous emphysema (air trapped underneath the skin). In addition to trauma to the tissues, bubbles can also build up in the blood vessels during rapid ascent and cause arterial gas embolisms, which can be lethal.  The video below provides a clear explanation for the physiology of these processes:

 

Middle Ear Barotrauma

This is the most common disorder among divers and the physiology behind it is similar to pulmonary barotrauma. Pressure in the middle ear normally equilibrates with ambient pressure via the eustachian tube. However, if upon descent this equalization is prevented by mucosal edema secondary to an upper respiratory infection, pregnancy, or anatomic variations, the negative pressure in the middle ear can lead to its filling with serous fluid/blood or to inward rupture of the tympanic membrane. It’s not life-threatening, but it can cause varying degrees of hearing loss or vertigo 🥴

Ear Barotrauma | Articles | Mount Nittany Health System

Paranasal Sinus Barotrauma

This is the second most common disorder after ear barotrauma. The mucosal engorgement and edema caused by descent can lead to entrapment of pressure within the sinuses and cause damage during the expansion of gas during rapid ascent.  May cause headaches or epistaxis (nosebleeding) 

sphenoid sinus (Patient) - Siteman Cancer Center

 

 

 

 

 

 

 

 

It’s worth noting that these very same injuries can occur from blast waves as well, which would obviously be more common in the combat environment. The brief video below explains:

Middle Ear/Paranasal Sinus

These are easy barotraumas to diagnose. The patient will have noticeable pain in these regions if they are affected. It’s very much the same pain as when your “ears can’t pop” while flying, although the patient can expect to be in much more pain and suffer from dizziness or hearing loss if the tympanic membrane ruptures.  

Pulmonary Barotrauma

It’s easy to suspect pulmonary barotrauma in general, but there are different types you need to look for:

  • Mediastinal/Subcutaneous emphysema: Refers to air build-up in the mediastinum (middle chest cavity) or under the subcutaneous skin layer. It can be very easy to detect; the affected area will appear swollen and will feel like tissue paper or rice crispies upon palpation. The video below demonstrates this nicely:

  • Pneumothorax: You know what this is! A collection of air built up between the lungs and the chest wall typically develops when gas ruptures from the lung parenchyma into the pleural space. The patient will experience chest pressure, difficulty breathing, decreased Sp02, tachypnea, etc.  Only occurs in about 10% of pulmonary barotrauma episodes

Tension Pneumothorax: Identification and treatment

 

  • Arterial Gas Embolism (AGE): This is the scariest one 😳… AGE is the passage of gas bubbles throughout the pulmonary and systemic vasculature can cause a wide range of symptoms.  Bubbles in the cerebral vasculature will cause stroke-like symptoms (altered mental status, unconsciousness, etc.); bubbles in the spinal cord will cause weakness, paralysis, numerous abnormal sensations. These will typically occur very soon after ascension or blast wave injury, which helps with the diagnosis.

Gas Embolism | NEJM

 

 

 

 

 

As we climb higher into the atmosphere, gases expand. Slowly descending in altitude will help decompress those gases and will hopefully prevent any further exacerbation of barotrauma.

 

Protect ear from water or further trauma (if the tympanic membrane is ruptured)

One of the primary functions of the tympanic membrane is to protect the middle and inner ear from the outside world.  If it ruptures, the ear will now be more vulnerable to physical damage.

Moxifloxacin (Avelox) 400mg PO daily if contamination is suspected

In addition to being susceptible to physical damage, the ear is also now susceptible to potential infections. If you suspect an infection (as noted by redness, swelling, etc.), you’ll want to treat this with antibiotics. Moxifloxacin is a potent broad-spectrum antibiotic that is commonly used for ear infections.

Pseudoephedrine (Sudafed) 60mg PO q4-6hr prn

Pseudoephedrine is a decongestant that will help clear up any mucous in the patient’s eustachian tubes, thus helping the patient equalize pressure differences and restore themselves back to normal.

DO NOT use ear drops!

Middle ear barotrauma is a mechanical issue, not an infectious one. Antibiotic ear drops are not indicated.

 

 

Again, patients with paranasal sinus barotrauma are not typically at risk for infections so no antibiotics are needed.  However, pseudoephedrine will still help clear out the sinuses and restore normal pressures.

SUDAFED® CONGESTION FOR SINUS PRESSURE | SUDAFED®

 

If there is no respiratory distress, monitor the patient closely. Use pulse oximetry if available

Not everybody is going to need aggressive treatment. We’re only concerned with treating those who exhibit signs of severe pathologies like pneumothorax, AGE, etc.  Pulse oximetry will help us determine if this is the case.

If respiratory distress occurs, treat as a pneumothorax

If the patient was around a blast or is conducting dive operations and they present with progressive respiratory distress and/or low Sp02 <90%, we can reasonably assume the patient is suffering from a pneumothorax.  Thus, you would treat this like any other pneumothorax in the TCCC setting with Needle Decompression.  If you have advanced capabilities, maybe even a chest tube if needed.

For severe symptoms or signs of AGE, administer 100% oxygen, 1L normal saline IV (150mL/hr), and evacuation to a recompression chamber.

The idea behind giving oxygen is that it will widen the pressure gradient for nitrogen between the bubble and the circulation and thus accelerate reabsorption of gas bubbles.  This is helpful for both mediastinal emphysema and AGE.  Fluid boluses of saline may help correct any shock from capillary leakage in AGE.  The only definitive treatment, however, is pressurized oxygenation from a recompression chamber…. which will require a special evacuation to a hospital with this capability.

5. If an upressurized airframe is used, avoid altitude exposure greater than 1000ft.

This is just a special note specifying how evacuation should be performed. A pressurized aircraft is convenient for transport because then you wouldn’t have to worry about gases expanding and exacerbating the barotrauma as you climbed in elevation. If the evac is via helicopter though, ensure that the crew does their best not to climb greater than 1000ft during a given period.

6. Treat per Pain Management protocol. Avoid narcotics

Pain control is appropriate with NSAIDS and Tylenol; narcotics are typically avoided in patients with pulmonary barotrauma due to the risk for respiratory depression. 

Barotrauma can be a tricky thing, no matter how minor it seems. Some follow-up will be required which will warrant at least a Routine evacuation.   A ruptured eardrum will typically heal on its own within a few weeks and small pockets of subcutaneous emphysema will also resolve in no time. However, those with severe pulmonary pathologies requiring advanced procedures or a recompression chamber will certainly need an Urgent evacuation for more definitive care and extensive follow-up.

 

Good luck out there! 

 

References

Brandon Simpson, PA-C
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