Hyperbaric oxygen therapy (HBOT) is being used more and more widely in neurological rehabilitation, yet the questions and misunderstandings surrounding it are just as common. How is it different from ordinary oxygen inhalation? Which conditions is it suitable for? And when is the best time to start?
Drawing on clinical practice, the chief physician of the Hyperbaric Oxygen Department at Nanjing Jianjia Rehabilitation Hospital has put together a systematic, science-based overview, unpacking the core points across four dimensions. What follows is a recap of the highlights of that sharing — we hope you find it useful.
Understanding Hyperbaric Oxygen: It Is Not the Same Thing as Ordinary Oxygen
Many people assume that HBOT is simply “enhanced oxygen inhalation”. In fact, the two work in completely different ways.
Ordinary oxygen (normobaric)
When breathing oxygen at 1 atmosphere, very little oxygen dissolves into the blood plasma; transport relies mainly on haemoglobin. Once a vessel is blocked, the oxygen simply cannot be delivered.
Hyperbaric oxygen (HBOT)
Inside a sealed chamber pressurised to 2.0–2.2 atmospheres, the patient breathes pure oxygen through a mask. Plasma-dissolved oxygen increases many times over and no longer depends on haemoglobin — oxygen can be “pressed” directly into ischaemic, oxygen-starved tissue.
The core mechanism
HBOT sharply raises the oxygen partial pressure in brain tissue (from roughly 30–40 mmHg at normal pressure to 150–250 mmHg), reversing the hypoxic state of the ischaemic penumbra. At the same time it reduces cerebral oedema, promotes neural repair, and improves the oxygen supply to the brainstem reticular activating system in patients with disorders of consciousness — a key target for awakening.
Six Common Misconceptions: How Many Have You Come Across?
Here are the six misconceptions seen most often in the clinic — and the truth behind each one.
Misconception 1: HBOT is just high-flow oxygen.
The truth: the mechanisms are completely different. Severe hypoxia, gas embolism and carbon monoxide poisoning must rely on HBOT; mask oxygen alone falls far short.
Misconception 2: HBOT can revive dead brain cells.
The truth: neurons that have already died cannot be brought back. HBOT only rescues the cells in the ischaemic penumbra that are nearing death but not yet lost.
Misconception 3: After cerebral haemorrhage, you must wait until everything is fully stable.
The truth: treatment can start once there is no active bleeding and the condition is stable — generally about one week after surgery for traumatic brain injury, and about two weeks after cerebral haemorrhage once a follow-up CT scan shows no fresh bleeding. Waiting too long wastes the 3–6 month golden window for repair.
Misconception 4: HBOT is a miracle cure for waking coma patients.
The truth: HBOT is one link in comprehensive rehabilitation. It must be combined with medication, neuromodulation (such as transcranial magnetic stimulation), sensory stimulation and complication management. Used alone, its effect is greatly diminished.
Misconception 5: The more sessions and the longer the course, the higher the chance of waking up.
The truth: staged assessment is recommended — in general, evaluate after 2–3 courses (40–60 sessions). If a continuous, full-dose course brings no improvement and imaging shows widespread brain necrosis, the benefit of continuing is very low.
Misconception 6: Once the illness has lasted more than 6 months, HBOT is completely useless.
The truth: for most patients efficacy declines after 6 months, but individual differences are large, and some trauma patients may still benefit from a short trial course. Neither giving up across the board nor treating endlessly without review is appropriate.
Which Conditions Can It Help, and How Is the Treatment Plan Timed?
The indications are broad and mainly include:
Acute indications
- Carbon monoxide poisoning
- Decompression sickness and air embolism
- Retinal artery embolism
- Brain dysfunction after cardiopulmonary resuscitation
- Crush injuries and delayed fracture healing
Neurological conditions
- Cerebral infarction and insufficient cerebral blood supply
- Traumatic brain injury
- Vegetative state
- Peripheral nerve injury
Other indications
- Sudden hearing loss
- Diabetic complications
Absolute contraindications (never enter the chamber)
- Untreated tension pneumothorax
- Active intracranial haemorrhage
- Multiple pulmonary bullae whose risk has not been assessed
Timing: treatment can begin once vital signs are stable, there is no active bleeding, intracranial pressure is under control, ventilator parameters are stable and there is no severe infection — there is no need to wait for months.
Key point: the golden window is within 6 months of onset. After 12 months the efficacy of HBOT alone drops significantly, although an individualised trial may still be considered.
Hyperbaric oxygen is an indispensable part of the comprehensive treatment of central nervous system injury and disorders of consciousness — but it is by no means a “miracle drug”. Grasping the window period, standardising the course of treatment, combining interventions and assessing dynamically: that is the scientific way.
Individuals differ. This article is for general health education only and is not a substitute for medical advice. If you feel unwell, please visit a hospital.