Barotrauma is tissue damage caused by a pressure difference between a gas-filled body space and the surrounding environment. It can affect the ears, sinuses, teeth, lungs, eyes, and gut, and it occurs in settings as varied as commercial flights, scuba dives, mechanical ventilation in intensive care, and explosive blasts. The underlying physics is straightforward: gas expands when surrounding pressure drops and compresses when pressure rises, and if a body cavity cannot equalize fast enough, the resulting strain injures soft tissue, ruptures membranes, or forces gas where it does not belong. What makes barotrauma medically interesting is how many different organs it can target and how dramatically the severity ranges from a few hours of ear pain to life-threatening arterial gas embolism.
Middle Ear Barotrauma
The middle ear is the body’s most frequent barotrauma site, largely because equalizing pressure there depends on a single narrow passage, the Eustachian tube, that has to open actively during pressure changes. When cabin pressure drops on a flight or ambient pressure rises during a dive, air needs to move in or out of the middle ear to keep the eardrum in a neutral position. If the Eustachian tube is swollen, congested, or simply slow to respond, the pressure difference stretches and eventually damages the tympanic membrane. Symptoms start with a sensation of fullness and ear pain and can progress to hearing loss, tinnitus, and in severe cases a ruptured eardrum with bleeding.
A mathematical model of middle ear pressure regulation found that the risk depends not only on how well the Eustachian tube functions but also on factors like the elevation difference between departure and destination airports and the ratio of eardrum displacement to middle ear volume. Interestingly, the model predicted that a completely blocked Eustachian tube can sometimes be less vulnerable to barotrauma than one that opens passively but fails to dilate when the muscles try to force it open, because the passive opening allows partial pressure shifts that then get trapped.1PubMed Central. Barotrauma during air travel: predictions of a mathematical model
Clinicians grade middle ear barotrauma by what the eardrum looks like under an otoscope. The Teed grading system ranges from grade 0, where there are symptoms but no visible changes, up to grade 5, where there is gross hemorrhage into the eardrum and frank rupture.2Annals of Emergency Medicine. Prevention of hyperbaric-associated middle ear barotrauma Most cases seen after flights or shallow dives fall in the lower grades and resolve on their own within days. Cases at the higher end, particularly those involving rupture, can require weeks to heal and occasionally need surgical repair.
When Barotrauma Reaches the Inner Ear
Inner ear barotrauma is rarer but considerably more serious than a simple middle ear squeeze. It can produce sudden sensorineural hearing loss, intense vertigo, and persistent tinnitus. The concern is a perilymph fistula, a tear in one of the thin membranes separating the fluid-filled inner ear from the air-filled middle ear. This can happen during a forceful attempt to equalize, such as aggressive nose-blowing or straining, or from external trauma like a slap to the ear.
A study of suspected perilymph fistulas found possible evidence of the tear during surgical exploration in nine out of ten cases, including fibrous tissue around the oval window and fluid pooling at the round window.3PubMed Central. Effects of early surgical exploration in suspected barotraumatic perilymph fistulas The time between injury and surgery in that group ranged from two to 47 days. Early exploration is generally favored when a perilymph fistula is suspected, because delays can allow further hearing deterioration. For divers, the practical takeaway is that sudden vertigo or hearing loss after a dive warrants urgent medical evaluation rather than a wait-and-see approach.
Sinus and Dental Barotrauma
The paranasal sinuses are rigid bony cavities lined with soft mucosa, and they depend on small openings called ostia to ventilate and equalize with the outside atmosphere. When those openings are blocked by swelling, polyps, or thick mucus, a pressure mismatch builds during ascent or descent. The result is sinus barotrauma, sometimes called barosinusitis, which produces facial pain, pressure sensation, and occasionally nosebleeds.4PubMed Central. Barosinusitis: Comprehensive review and proposed new classification system The frontal and maxillary sinuses are affected most often because they have the longest and narrowest drainage pathways.
Dental barotrauma, called barodontalgia, is toothache triggered by pressure changes. It was once assumed that gas trapped between a tooth and its filling expanded and cracked the restoration. More recent analysis suggests the real culprit is usually secondary decay hidden underneath a filling; the pressure shift drives fluid through the porous decayed dentin, irritating the pulp.5PubMed Central. Pathophysiology of Barodontalgia: A Case Report and Review of the Literature In a survey of Turkish pilots, roughly four in five who experienced barodontalgia reported it at relatively low altitudes, and the strongest risk factors were existing cavities, prior fillings, root canal treatments, and teeth-grinding habits.6PubMed Central. Relationships among barodontalgia prevalence, altitude, stress, dental care frequency, and barodontalgia awareness: a survey of Turkish pilots The message for anyone who flies or dives regularly is that keeping dental work in good repair is a surprisingly effective form of barotrauma prevention.
Pulmonary Barotrauma in Diving
Lung barotrauma during a dive is one of the most dangerous pressure injuries because it can lead to air entering the bloodstream. The mechanism is simple: as a diver ascends, the compressed air in the lungs expands. If the diver holds their breath or ascends faster than the air can escape through normal exhalation, the expanding gas can tear lung tissue. The frightening reality is that this can happen during an uncontrolled ascent from as little as one meter of depth, as long as the diver is breathing compressed air.7Prehospital and Disaster Medicine. A Review of Pulmonary Barotrauma in Scuba Diving Accidents
Once lung tissue tears, gas can track into several places. It can leak into the space between the lung and chest wall, causing a pneumothorax, or into the tissue around the heart, producing a pneumomediastinum. The most feared outcome is arterial gas embolism, where gas is forced into pulmonary blood vessels and carried to the brain or other organs, causing stroke-like symptoms within seconds of surfacing.8PubMed. Arterial gas embolism and decompression sickness A study of 15 divers with pulmonary barotrauma found that arterial gas embolism was the presenting problem in 13 of them, with pneumothorax and mediastinal emphysema accounting for the rest.9PubMed. Risk factors for pulmonary barotrauma in divers
Certain anatomical features raise a diver’s risk. Lung blebs and bullae, which are small pockets of trapped air in the lung lining, are thought to rupture more easily under pressure changes. Military diver populations with unusually large lung volumes have been investigated for this connection after clusters of barotrauma cases.10PubMed Central. Large lungs in divers: a risk for pulmonary barotrauma? Asthma, chronic obstructive pulmonary disease, and any condition that creates air trapping are also considered risk factors, which is why dive medical screenings ask about respiratory history.
Distinguishing Barotrauma From Decompression Sickness
A common source of confusion after a diving accident is whether the diver’s symptoms come from barotrauma with arterial gas embolism or from decompression sickness, sometimes called “the bends.” Both involve gas bubbles causing harm, but they arise through different mechanisms. Arterial gas embolism results from lung rupture forcing air directly into the arterial system, and the onset is typically sudden, often within moments of surfacing, with stroke-like symptoms such as one-sided weakness, vision changes, or loss of consciousness. Decompression sickness, by contrast, develops because dissolved nitrogen comes out of solution in the blood and tissues during ascent, forming bubbles that accumulate gradually. Its symptoms tend to be more varied and slower to appear: joint pain, skin rashes, tingling, and sometimes spinal cord or inner ear involvement.11PubMed. DCS or DCI? The difference and why it matters
In practice, the two conditions can overlap, and field-level providers often cannot distinguish them reliably. The umbrella term “decompression illness” is used to cover both. From a first-aid standpoint, the initial treatment is the same regardless: high-flow oxygen and rapid evacuation to a facility with a hyperbaric chamber. The distinction matters more for long-term management and for understanding what went wrong during the dive.
Ventilator-Induced Barotrauma
Outside the diving world, the most clinically significant form of lung barotrauma happens in hospital intensive care units when mechanical ventilators deliver air at pressures high enough to rupture fragile lung tissue. Patients on ventilators, especially those with already damaged lungs from pneumonia or acute respiratory distress syndrome, are at elevated risk because their remaining functional lung tissue is stiffer and less compliant, concentrating the delivered pressure into smaller areas.
The general guideline is to keep peak alveolar pressures below about 35 centimeters of water to reduce the risk of pressure-related lung injury.12PubMed Central. High-inflation pressure and positive end-expiratory pressure. Injurious to the lung? Yes. Lung-protective ventilation strategies aim for low tidal volumes, around 6 milliliters per kilogram of ideal body weight, with plateau pressures kept well below that threshold.13PubMed. Evaluation of a ventilation strategy to prevent barotrauma in patients at high risk for acute respiratory distress syndrome These strategies have become standard practice in critical care over the past two decades.
The COVID-19 pandemic complicated the picture. Two patients with COVID-19 pneumonia developed subcutaneous emphysema and pneumomediastinum despite being ventilated at pressures within what are normally considered safe ranges. A retrospective study cited in the same report found that barotrauma incidence in COVID-related respiratory distress syndrome reached about 15%, compared with roughly 0.5% in respiratory distress from other causes at similar ventilator settings.14American Journal of Case Reports. Pulmonary Barotrauma Resulting from Mechanical Ventilation in 2 Patients with a Diagnosis of COVID-19 Pneumonia The virus itself appeared to weaken lung tissue enough that even modest pressures could cause rupture. This highlighted a recurring theme in barotrauma medicine: the state of the tissue matters as much as the pressure applied to it.
Mask Squeeze and Ocular Barotrauma
Scuba divers who forget to exhale through their nose into their mask during descent can develop “mask squeeze,” a form of facial barotrauma. As the diver descends, the air inside the mask compresses and creates a relative vacuum against the face. The suction effect can burst small blood vessels in the eyelids and the whites of the eyes, producing dramatic-looking petechial hemorrhages, chemosis, and sometimes proptosis, where the eye appears to bulge forward.15PubMed. Non-traumatic subperiosteal orbital hemorrhage secondary to barotrauma In one case, a diver who also performed a forceful Valsalva maneuver during the dive developed a subperiosteal orbital hemorrhage with double vision alongside the lid hemorrhages.
The fix is remarkably simple: exhale a small amount of air through the nose into the mask periodically during descent. This equalizes the pressure inside the mask with the surrounding water pressure.16PubMed. Ocular barotrauma caused by mask squeeze during a scuba dive Mask squeeze is almost exclusively a beginner’s injury, but even experienced divers can encounter it if distracted or if their mask leaks and they descend too quickly to notice.
Blast-Related Barotrauma
Explosions produce a rapid overpressure wave followed by an underpressure phase, and this blast wave causes primary blast injuries that are a form of barotrauma on a catastrophic scale. The organs most vulnerable are those containing gas: the lungs, the ears, and the bowel. “Blast lung” can present as acute respiratory distress, with pulmonary hemorrhage and air embolism. The eardrums are often the first structures to rupture, and tympanic membrane perforation is sometimes used as a screening indicator for whether a blast victim is likely to have sustained more serious internal injuries.17PubMed Central. Blast Injuries
One of the clinical challenges with blast barotrauma is that injuries can be covert. A person may walk away from an explosion with intact skin and no visible wounds but have ruptured eardrums, pulmonary contusions, or developing bowel ischemia from air forced into the mesenteric vessels. Emergency providers in blast scenarios are trained to evaluate everyone exposed to the overpressure zone, regardless of whether they look injured externally.
Treatment and Emergency Management
Treatment for barotrauma varies enormously depending on the site and severity, but a few principles run across nearly all forms. For mild middle ear or sinus barotrauma, management is largely supportive: oral decongestants to open the Eustachian tubes or sinus ostia, pain relief, and time. Antibiotics are added when there is a ruptured eardrum or evidence of secondary infection. Most cases resolve within days to a few weeks without intervention.
When arterial gas embolism is suspected after a diving accident or iatrogenic air entry, the priorities shift to high-flow 100% oxygen as quickly as possible. The high oxygen concentration creates a diffusion gradient that helps nitrogen wash out of intravascular bubbles, shrinking them, while also improving oxygen delivery to tissues deprived by the vascular obstruction.18Medical Research Archives. Air embolism- Incidence of Uncommon Causes, Diagnostic and Treatment Challenges This is a bridge treatment, though, not a cure. The definitive therapy for arterial gas embolism is recompression in a hyperbaric chamber, which physically compresses the bubbles back into solution and then allows controlled, slow decompression to let the gas clear safely.
Recompression is not always possible. In one case of cerebral arterial gas embolism that occurred during open-water scuba training, the diver also had a pneumothorax. Putting that patient into a hyperbaric chamber was too risky because decompressing the chamber afterward could have converted the pneumothorax into a life-threatening tension pneumothorax. The patient was treated with high-flow normobaric oxygen alone and did not relapse neurologically.19PubMed Central. Cerebral arterial gas embolism (CAGE) during open water scuba certification training whilst practising a controlled emergency swimming ascent Cases like this demonstrate that field decisions about barotrauma treatment are rarely cookbook; the specific combination of injuries drives the plan.
Prevention and Equalization Techniques
For ear barotrauma, prevention centers on equalization maneuvers that open the Eustachian tube during pressure changes. The three techniques divers and flyers use most are the Valsalva (pinching the nose and gently blowing), the Frenzel (using the tongue as a piston to compress air upward while the glottis stays closed), and the Toynbee (swallowing with the nose pinched). A pressure-chamber study comparing these three found that the Valsalva produced the highest opening pressure and took the longest to equalize, while the Toynbee generated the lowest pressure and equalized fastest. The Frenzel fell in between. All three were equally effective at actually moving air through the Eustachian tube, but the gentler methods are generally preferred during dives because a forceful Valsalva can overpressurize the middle ear and itself cause damage.20PubMed Central. Prospective study on the Eustachian tube function during Frenzel maneuver in a hypobaric/hyperbaric pressure chamber
For ventilator-induced barotrauma, prevention is built into modern ventilator protocols. Lung-protective ventilation with low tidal volumes and limited plateau pressures has become the default approach for patients with acute respiratory distress syndrome. The evidence from the COVID-19 era suggests that even these standard safeguards may not be sufficient when the underlying lung disease is particularly destructive, prompting ongoing research into which patients need even more conservative pressure limits.
For sinus and dental barotrauma, the best prevention is managing the underlying condition. Divers and aircrew with active upper respiratory infections are advised to postpone exposure to pressure changes. Regular dental checkups to catch hidden decay under old fillings can prevent barodontalgia before it becomes a problem at altitude or depth.
Why Children Are More Vulnerable
Children experience middle ear barotrauma more frequently than adults, and the reason is anatomical. A child’s Eustachian tube is shorter, more horizontal, and softer than an adult’s, which makes it less efficient at ventilating the middle ear and more prone to collapse or obstruction.21PubMed Central. The Eustachian Tube Dysfunction in Children: Anatomical Considerations and Current Trends in Invasive Therapeutic Approaches The same anatomical features that make children susceptible to middle ear infections also make them susceptible to barotrauma during flights. Parents who have flown with a screaming toddler during descent have witnessed this firsthand. Feeding a bottle, using a pacifier, or encouraging swallowing during the descent phase can help by activating the muscles that open the tube.
The Eustachian tube gradually elongates and angles more steeply downward as the skull grows through childhood and into the teenage years. By late adolescence, most people have an adult-type tube and a correspondingly lower risk of pressure-equalization problems. Children with chronic ear issues, enlarged adenoids, or a history of recurrent middle ear infections are at particularly high risk and may benefit from decongestant drops before flights, though the evidence for pharmacological prevention in this age group remains mixed.
How Marine Mammals Avoid Barotrauma
If pressure changes injure human tissues at relatively modest depths, how do dolphins and whales dive to hundreds or thousands of meters without destroying their lungs? The answer involves a set of adaptations that humans simply do not have. One key mechanism is controlled lung collapse: as a marine mammal descends, the flexible chest wall allows the lungs to compress progressively, pushing air out of the gas-exchanging alveoli and into the reinforced upper airways where gas absorption is minimal. This limits how much nitrogen dissolves into the blood, which should theoretically protect against both lung barotrauma and decompression sickness.
A hypothesis published in the Proceedings of the Royal Society B proposes that cetaceans may go further by actively managing the mismatch between ventilation and blood perfusion in the lung. By selectively perfusing only the collapsed portions of the lung at depth, they could exchange oxygen and carbon dioxide while limiting nitrogen uptake, thanks to differences in how readily each gas crosses the membrane.22PubMed Central. Pulmonary ventilation–perfusion mismatch: a novel hypothesis for how diving vertebrates may avoid the bends Modeling work on bottlenose dolphins predicts that their blood and tissue nitrogen levels during routine dives should reach concentrations that would cause severe decompression sickness symptoms in a land mammal of similar size. Yet the dolphins appear unbothered, suggesting they rely on physiological or possibly immunological mechanisms that humans do not share.23Frontiers in Marine Science. How Do Marine Mammals Manage and Usually Avoid Gas Emboli Formation and Gas Embolic Pathology? Critical Clues From Studies of Wild Dolphins
This research has more than academic interest. Understanding how evolution solved the barotrauma problem in marine mammals may eventually inform better prevention strategies for human divers or even ventilator design. For now, though, the gap between a dolphin’s lungs and ours remains a humbling reminder of how poorly equipped the human body is for the pressure environments we routinely enter with technology.
Caisson Disease and the Industrial Origins of Barotrauma Medicine
Modern understanding of pressure-related injury owes a surprising amount to 19th-century civil engineering. When workers began using pressurized caissons to build bridge foundations and tunnels underwater, they experienced mysterious symptoms after returning to normal atmospheric pressure: joint pain, paralysis, and sometimes death. Physicians studying these workers pieced together that the compressed air the laborers breathed at depth dissolved nitrogen into their blood and tissues, which then formed bubbles upon too-rapid decompression. By studying thousands of casualties, they identified the cause, developed staged decompression protocols, and eventually established recompression treatment.24PubMed Central. Discovery of caisson disease: a dive into the history of decompression sickness
The term “caisson disease” and the colloquial “the bends” (reportedly named because affected workers bent over in pain) entered the medical vocabulary during this period. The Brooklyn Bridge construction in the 1870s was one of the more notorious settings, with the project’s chief engineer himself severely affected. Those hard-won observations laid the groundwork for dive tables, hyperbaric oxygen therapy, and the broader field of undersea and hyperbaric medicine that treats barotrauma patients today.