Oxygen Toxicity During a Long Hyperbaric Treatment
A 52-year-old man is being treated for a chronic non-healing wound with a hyperbaric protocol at 2.4 ATA for 90 minutes on 100% oxygen. At 70 minutes into the treatment he develops tingling around the mouth, twitching of the right hand, and anxiety. He is awake and talking. The chamber is a multiplace chamber with an inside attendant. His vital signs are stable and his oxygen saturation is 100%.
1. What is happening, and what is your immediate action?
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This is central nervous system oxygen toxicity - perioral tingling, hand twitching, and anxiety are classic early signs (the 'Venturi' premonitory symptoms). The immediate action is to remove the oxygen source: have the patient breathe chamber air (or a reduced oxygen fraction) and stop the oxygen exposure. Do not wait for a seizure.
In a multiplace chamber, the inside attendant manages the patient directly. The treatment is interrupted, the patient is observed, and the hyperbaric physician is notified. If a seizure occurs, protect the airway and prevent injury; the seizure usually self-terminates when oxygen is removed.
2. How do you decide whether to resume the treatment, and what changes would you make?
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Resume only after symptoms fully resolve and with a modified protocol: lower the oxygen partial pressure (e.g., reduce depth to 2.0 ATA), shorten the oxygen periods, and add air breaks (e.g., 5 minutes of air every 20–30 minutes). The goal is to deliver a therapeutic dose while keeping the oxygen partial pressure and exposure time below the toxicity threshold.
The judgment: oxygen toxicity is dose- and time-dependent; the response is to reduce the dose, not necessarily to abandon hyperbaric therapy. Document the event and the modification.
3. What patient factors would make you more cautious about oxygen toxicity on future treatments?
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Factors that lower the seizure threshold or increase susceptibility: fever, hypoglycemia, fatigue, caffeine or stimulant use, prior history of seizures, and possibly CO2 retention. Also relevant: the patient's work of breathing and any anxiety that increases ventilation.
Practical steps: screen for fever and hypoglycemia before treatment, avoid stimulants, keep the patient calm, and use air breaks routinely. In a patient who has had a toxicity event, consider a lower treatment pressure and closer monitoring.