Hyperbaric Oxygen Therapy (HBOT) involves a patient breathing 100% oxygen while inside a pressurized chamber. This process significantly increases the amount of oxygen dissolved in the bloodstream, allowing it to reach tissues that may be deprived of oxygen. While HBOT is generally a safe and well-tolerated medical treatment for a variety of conditions, it is not suitable for everyone. Careful screening is required to identify specific medical conditions or circumstances that make the therapy too risky.
Immediate and Life-Threatening Exclusions
The most critical absolute exclusion for HBOT is the presence of an untreated pneumothorax, or collapsed lung. Air is trapped between the lung and the chest wall, which can dangerously expand when the chamber pressure is increased during treatment. The subsequent decompression can lead to a potentially fatal tension pneumothorax, where the trapped air pressure compresses the heart and major blood vessels. A chest X-ray is often required before initiating therapy to rule out this complication.
Certain chemotherapy agents also constitute an immediate exclusion because of their interaction with high-pressure oxygen. Doxorubicin, for instance, can become significantly more cardiotoxic—harmful to the heart—when combined with HBOT. Similarly, Cisplatin is a concern as the combination with hyperbaric oxygen may weaken the tensile strength of healing wounds. Increased oxygen levels can also amplify the toxicity of agents like Bleomycin, which is known to cause lung damage. For elective HBOT, these systemic agents must be discontinued and cleared from the patient’s system to mitigate the risk of severe toxicity.
Risks Associated with Pressure Changes
Many HBOT exclusions relate to the physical effects of pressure changes, which can cause injury to gas-filled spaces in the body. Patients with severe, uncontrolled Chronic Obstructive Pulmonary Disease (COPD) are at heightened risk of barotrauma, which is damage caused by pressure differences. Air can become trapped in the lungs due to conditions like emphysema or bullae, and the subsequent expansion of this trapped air during decompression can lead to a lung rupture or pneumothorax.
The ability to equalize pressure in the middle ear and sinuses is a major factor in determining candidacy. Active ear or sinus infections, or even a common cold, can swell the mucous membranes and block the narrow passages that connect these spaces. If a patient cannot equalize this pressure, the difference in pressure between the chamber and the body’s internal cavities can cause barotrauma.
This pressure imbalance can result in painful conditions like middle ear squeeze, where the eardrum is pushed inward, or a sinus squeeze, which may cause severe pain, nosebleeds, or damage to the sinus linings. Individuals who have recently undergone thoracic, ear, or sinus surgery are also temporarily excluded from HBOT. The pressure changes could disrupt surgical repairs or newly forming scar tissue.
Drug Interactions and Acute Temporary States
Certain medications are known to increase the risk of oxygen toxicity, which can manifest as central nervous system symptoms like seizures. Disulfiram, an agent sometimes used for alcohol aversion therapy, blocks the production of the protective antioxidant superoxide dismutase. This inhibition increases the body’s susceptibility to oxygen toxicity, making HBOT unsafe while the patient is taking the medication.
Mafenide Acetate, a topical agent used in burn care, is also a concern. This drug acts as a carbonic anhydrase inhibitor, which can lead to carbon dioxide retention in the body. The resulting increase in carbon dioxide promotes vasodilation and increases cerebral blood flow, which heightens the risk of an oxygen-induced seizure.
Certain temporary states require the postponement of HBOT until they are resolved. A patient with an uncontrolled high fever, typically above 102 degrees Fahrenheit, may have a lowered seizure threshold, and the hyperoxic environment can further increase this risk. Similarly, an active seizure disorder must be medically controlled before a patient can safely enter the chamber. Severe claustrophobia, where a patient cannot tolerate the enclosed chamber space, may be an exclusion until the condition is managed.