Evaluation of a Patient for Safety of Hyperbaric Oxygen Treatment

In addition to ensuring that HBO is indicated for the disease process in question, it is important to assess the patient in terms of general effectiveness and safety of HBO. The following issues should be addressed:

Whether a sufficient elevation in PaO₂ can be obtained

Whether the patient can equilibrate middle ear pressure

Adequacy of control of seizure disorders

Optimization of reversible obstructive lung disease and the presence of pulmonary bullae or blebs

Whether hyperoxic myopia might critically affect vision

Whether claustrophobia might occur during treatment

The predicted PaO₂ in a hyperbaric chamber may be calculated by using Equation 8. It can easily be predicted, for example, that a patient who has sufficient lung disease or injury such that PaO₂ during treatment would not exceed 1000 mm Hg would probably obtain marginal benefit from HBO unless the reason for HBO is gas bubble disease.

The ability to vent the middle ear may be estimated by directly observing the tympanic membrane while the patient holds his nose or performs a Valsalva maneuver. Movement of the eardrums indicates a patent eustachian tube and the ability to equilibrate middle ear pressure. If otic barotrauma is unlikely to be avoided (e.g., with mental obtundation or the presence of an endotracheal tube) or if a condition is present that may render the patient susceptible to inner ear injury (e.g., stapedectomy), myringotomy or tube placement are options.

The presence of pulmonary bullae or blebs should be considered relative contraindications to HBO treatment. The low risk of pulmonary barotrauma must be weighed against the urgency or efficacy of HBO for treatment of the patient's disease process.

Because hyperoxia may result in generalized seizures, it is prudent to ensure that anticonvulsant medication has been optimized. It should be noted that HBO will accelerate existing pulmonary O₂ toxicity. Therefore, significant pre-HBO exposure of the patient to high levels of inspired O₂ may also be a relative contraindication to HBO therapy, depending on the urgency of treatment.

For patients requiring more than 20 to 30 HBO treatments, periodic confirmation of visual acuity may be helpful to determine the onset of hyperbaric myopia.

Because most hyperbaric chamber systems are small and cramped, patients who cannot tolerate enclosed spaces may require anxiolytic therapy to facilitate toleration of HBO therapy.