Safety Instructions for the Compression Stage of Mild Hyperbaric Oxygen Supplementation

The compression phase refers to the entire process in which the pressure inside the mild hyperbaric oxygen chamber rises steadily and gradually from normal atmospheric pressure to the standard oxygen supplementation pressure, which normally lasts 60 to 90 minutes. During compression, slight noise and a minor temperature rise will occur inside the chamber. These are normal physical phenomena caused by pressure changes. There is no need to be nervous or panicked; just stay calm.

The primary safety risks during compression are middle ear barotrauma and sinus barotrauma. As long as occupants follow the staff’s instructions properly and perform pressure equalization maneuvers correctly throughout the session, risks can be minimized to ensure safe oxygen supplementation.

### I. Core Priority: Proper Middle Ear Pressure Equalization to Prevent Ear Pain and Injury

As chamber pressure keeps rising, a significant pressure difference builds up between the inside and outside of the human middle ear cavity, resulting in sensations such as ear fullness, ear distension and tinnitus — much like the ear discomfort felt during aircraft takeoff. Do **not** wait until ear pain sets in before equalizing pressure. Perform equalization actively and intermittently throughout compression to balance ear pressure in advance.

Three safe and effective equalization methods are recommended for different users; they are simple to operate and highly safe:

✅ **Swallowing method**: Swallow saliva repeatedly, or sip water slowly. This is the simplest and safest method, suitable for most occupants. Perform it once every 30 to 60 seconds on a rotating basis.

✅ **Chewing method**: Chew sugar-free soft candies. Movement of the jaw joint naturally opens the Eustachian tubes to equalize ear pressure. Chew slowly and gently to prevent choking. Crumbly or hard snacks are prohibited to avoid foreign-body hazards.

✅ **Valsalva maneuver**: Pinch both nostrils shut, keep your mouth closed, and blow air gently and slowly into your nasal cavity. A faint popping sensation in the ears indicates the Eustachian tubes have opened and pressure is balanced. Never blow forcefully or aggressively, as excessive pressure may damage or rupture the eardrum.

**Important Emergency Reminder**: If persistent ear pain, sinus soreness, worsening head fullness or other discomfort develops during compression, **do not tough it out**. Immediately call staff via the intercom inside the chamber or signal by raising your hand. Staff will slow or pause compression and take appropriate action. If discomfort persists despite repeated equalization attempts, compression will be stopped and decompression initiated for you to exit the chamber promptly to protect against eardrum rupture, sinus injury and other harm.

In addition, the Eustachian tubes function poorly during colds, nasal congestion or flare-ups of rhinitis, which greatly raises the risk of barotrauma. You must inform staff voluntarily before entering the chamber. Staff will assess your condition to determine whether oxygen supplementation can proceed. Never conceal such symptoms.

### II. Report Discomfort Promptly; Do Not Endure Symptoms

Besides ear and sinus discomfort, immediately notify chamber staff and describe your condition clearly if you develop dizziness, headache, palpitations, chest tightness, numbness of the face or lips, nausea, fatigue, cold sweats or any other abnormal symptoms. Never wait or delay reporting.

### III. Follow Chamber Rules Strictly for Safe Oxygen Supplementation

All occupants change into dedicated cotton anti-static garments before entry. A mild temperature increase occurs during compression; adjust your posture moderately for comfort. Do not touch any valves or control switches inside the chamber, and avoid pulling tubing or oxygen cannulas. Remain seated, refrain from large body movements and do not walk around inside.

Follow all instructions from the chamber operator and cooperate with procedures in order. No shouting, restlessness or unprompted standing is permitted in the enclosed chamber.

A full check for prohibited items is completed before entry. Mobile phones, lighters, sharp metallic objects and all flammable or explosive items are strictly forbidden inside the chamber at all times to prevent safety incidents.

#### Special Instructions for Accompanying Persons

Once compression finishes smoothly and chamber pressure reaches the standard level, the session enters the core stable-pressure oxygen inhalation phase. Safe mild hyperbaric oxygen supplementation relies on professional oversight by staff and active cooperation from occupants. A solid understanding of compression-phase knowledge and coordination tips effectively reduces discomfort and helps everyone complete the full oxygen supplementation session calmly and safely.