Hyperbaric Oxygen Therapy (HBOT) is a medical treatment that involves breathing 100% oxygen inside a specialized chamber where the air pressure is increased to a level two to three times greater than normal atmospheric pressure. HBOT dramatically increases the amount of oxygen dissolved directly into the bloodstream, allowing it to reach tissues deprived of adequate oxygen supply. While HBOT is a well-established treatment for conditions like decompression sickness, stubborn wounds, and carbon monoxide poisoning, its application also extends to compromised sensory organs. For hearing loss, the therapy primarily focuses on restoring function to the delicate structures of the inner ear.
How Hyperbaric Oxygen Therapy Works
The therapeutic effect of HBOT hinges on the principles of physics. Under normal conditions, oxygen in the blood is primarily bound to hemoglobin in red blood cells. When a patient breathes pure oxygen in a pressurized environment, the increased pressure causes a much larger volume of oxygen to dissolve directly into the blood plasma.
This “super-oxygenated” plasma delivers oxygen far beyond the normal capacity of red blood cells. The inner ear, specifically the cochlea, has a limited blood supply and is highly vulnerable to oxygen deprivation. This mechanism provides a means to bypass localized blockages or areas of poor circulation. The extra dissolved oxygen saturates the inner ear fluids, including the perilymph and endolymph, which bathe the sensory hair cells.
By overcoming tissue hypoxia (a lack of oxygen), HBOT helps sustain the metabolic needs of the auditory cells. The therapy also exerts anti-inflammatory effects by reducing swelling in the affected inner ear tissues. This dual action of increased oxygen delivery and inflammation reduction is theorized to aid in the recovery of damaged hair cells and neural pathways within the cochlea.
Hearing Loss Conditions Treated with HBOT
HBOT is not a general treatment for all forms of hearing impairment, such as age-related or conductive hearing loss. Instead, its use focuses on the urgent medical situation known as Sudden Sensorineural Hearing Loss (SSNHL). This condition is defined as a rapid, unexplained loss of hearing of at least 30 decibels across three consecutive frequencies, typically occurring over a 72-hour period.
The underlying cause of SSNHL is often idiopathic (unknown), but is frequently attributed to viral infections, circulatory disturbances, or inflammatory processes affecting the inner ear. Because the delicate sensory hair cells in the cochlea are highly sensitive to oxygen deprivation, SSNHL is considered a medical emergency. The effectiveness of HBOT depends heavily on the timing of intervention.
For the therapy to have the best chance of success, it should ideally be initiated within two weeks of the hearing loss onset, though it may be used as a salvage therapy up to one month later. This narrow window reflects the rapid, irreversible damage that can occur when inner ear structures are deprived of oxygen. While SSNHL is the primary indication for HBOT in audiology, some research has explored its role in cases of acute acoustic trauma or noise-induced hearing loss.
The HBOT Treatment Protocol
A typical course of HBOT for sudden hearing loss involves a series of daily treatments in a specialized pressure chamber. Treatment is delivered in one of two chamber types: a monoplace chamber (a clear acrylic tube accommodating a single patient) or a multiplace chamber (a large room where multiple patients are treated simultaneously while breathing pure oxygen through a mask or hood).
The standard pressure used for treating SSNHL ranges from 2.0 to 2.5 atmospheres absolute (ATA), equivalent to the pressure experienced 33 to 50 feet below the ocean surface. Each session lasts between 90 and 120 minutes. The session begins with a compression phase, where pressure is slowly increased, and the patient must actively perform ear-clearing techniques, such as swallowing or yawning, to equalize middle ear pressure.
Once the target pressure is reached, the patient breathes 100% oxygen intermittently, often with short “air breaks” of normal air to reduce the risk of oxygen toxicity. The overall treatment regimen typically consists of 10 to 20 sessions administered daily, usually five to seven days a week. This schedule provides a sustained, high-dose oxygen environment to the recovering inner ear tissues. The final stage is a gradual decompression phase, returning the chamber pressure to normal atmospheric levels.
Safety Profile and Potential Side Effects
While HBOT is a safe procedure when administered in accredited facilities, the combination of increased pressure and concentrated oxygen carries specific risks. The most frequent side effect is barotrauma, which is damage caused by pressure changes affecting air-filled spaces, particularly the middle ear and sinuses. Patients may experience ear pain, a feeling of fullness, or, in rare instances, a rupture of the eardrum during compression or decompression.
To mitigate this, patients are taught pressure equalization maneuvers. In cases of persistent difficulty, a doctor may recommend placing a temporary pressure-equalizing tube in the eardrum. Less common, but more serious, risks are related to the high concentration of oxygen. Oxygen toxicity, which can manifest as a seizure, is a rare complication managed by following strict treatment protocols, including intermittent air-breathing breaks.
Patients may also experience temporary changes in vision, such as a short-term increase in nearsightedness, which usually resolves within weeks of completing the therapy. Specific contraindications prevent a patient from receiving HBOT, including having an untreated collapsed lung (pneumothorax) or certain types of active lung disease. A thorough medical evaluation is performed before beginning treatment to ensure patient safety and suitability.