HBO Nuggets of the Week

A forum to discuss interesting aspects of hyperbaric medicine.

Friday, January 15, 2016

HBO Nugget 16

HBO Nugget 16

Hyperbaric oxygen therapy (HBOT) is usually very well tolerated. The most common risk to patients is barotrauma, typically middle ear.  Other risks of prolonged exposure to oxygen include pulmonary oxygen toxicity and central nervous system seizures. Pulmonary oxygen toxicity is rarely seen since it requires long exposures at a FiO2 of greater than 50%. This is more commonly seen in ventilated patients in the ICU. Central nervous system oxygen toxicity, also known as the Paul Bert Effect, may be more of a concern since some medical conditions lower the threshold for seizures to occur.

Patients at high risk for seizures who are recommended to undergo HBOT may benefit from air breaks during their dive to reduce the total time of hyperoxic exposure. A patient will be supplied a non-rebreather mask that is connected through the chamber wall to medical air. During the dive, the hyperbaric technician will request that the patient apply the mask and breath air. A typical protocol is for the patient to breathe medical air for 5 minutes after every 30 minutes.

During the initial medical evaluation, the healthcare provider should ascertain whether the patient may be at high risk for seizures or have a seizure disorder.  Air breaks should be considered for those patients that have:

·        Epilepsy

·        Recent brain surgery

·        Brain tumors

·        Recent head trauma/concussion

·        Fever related seizures

·        Infections such as brain abscess, meningitis, encephalitis

·        Stroke

·        Diving the patient at pressures  > 2.0 ATA

Consultation with a neurologist/neurosurgeon prior to starting HBOT can be helpful as well as making sure that the patient continues any anti-convulsant medication that they are taking.

Should the patient have a seizure during his/her treatment and breathing is irregular, ascending the patient rapidly may not be prudent.  Rapid ascent without regular breathing may predispose the patient to lung rupture/pneumothorax. When breathing becomes regular, ascent may be started.