What Actually Happens During a Professional HBOT Session
Assessment, pressurization, ear equalization, session length and how many treatments to expect - a step-by-step look at a clinical HBOT session based on major medical centers.
Before you go in
Hyperbaric oxygen therapy is usually done as an outpatient procedure. According to Johns Hopkins Medicine, patients are typically asked to change into a medical gown made of 100 percent cotton and to remove items that could pose a fire or pressure risk, since the chamber environment is oxygen rich. A clinician reviews your history and the reason for treatment before the session begins.
Because oxygen supports combustion, hyperbaric units enforce strict safety rules. Lighters, battery-powered devices, and petroleum-based hair or skin products are generally kept out of the chamber, and staff will confirm you are not carrying anything prohibited. These rules are routine, and following them is part of what makes treatment in an accredited facility safe.
The setting depends on the chamber type. In a monoplace unit you lie on a padded table that slides into a clear acrylic tube roughly seven feet long. In a larger room-style chamber, several people can be treated at once while seated.
Pressurization and breathing oxygen
Once the chamber is sealed, the pressure is gradually raised. Mayo Clinic describes air pressure inside the chamber being increased to about two to three times normal atmospheric pressure, while Johns Hopkins cites pressures up to roughly 2.5 times normal. At that pressure you breathe close to 100 percent oxygen, which allows the blood plasma to carry far more oxygen than usual to the tissues.
You are asked to relax and breathe normally. In many chambers you can watch television or listen to music, and you can speak with the technician throughout. The staff monitors you for the whole session.
Equalizing your ears
The most commonly noticed sensation is in the ears. As pressure rises, Johns Hopkins notes that the ears may feel plugged or may pop, similar to an aircraft descent, and mild discomfort is described as normal. Technicians usually teach simple equalization techniques such as swallowing, yawning, or gently clearing the ears so pressure balances across the eardrum. Letting staff know early if the pressure feels uncomfortable allows them to slow down.
Length, session counts and afterward
A single session commonly lasts between about 30 minutes and two hours. Mayo Clinic puts a typical treatment at roughly one and a half to two hours. How many sessions are needed depends entirely on the condition being treated, and both centers stress that this is set by the treating team, not by a fixed rule. Wound-related protocols in particular can run to many sessions.
After treatment the chamber is depressurized slowly. Johns Hopkins notes some people feel lightheaded or tired afterward, and that this usually passes fairly quickly. Mayo Clinic notes that possible side effects can include temporary changes in vision and, less commonly, ear or sinus injury from the pressure change, which is another reason equalization is practiced carefully.
The chamber type shapes the whole experience, from how you lie down to how you equalize, and an overview of single-person systems at monoplace chambers can make a first appointment feel less unfamiliar. Even so, the details of your own protocol, including pressure and session count, should be set and explained by the physician and hyperbaric team responsible for your care.