As with any treatment, side effects are possible. However, with hyperbaric oxygen therapy they are minimal. The most common is barotrauma to the ears and sinuses caused by pressure changes.

Patients are taught autoinflationary techniques to promote adequate clearing of the ears during treatment. Decongestants may be helpful. This problem is temporary and resolves when HBO treatment is completed.

If the patient has ear pain or is unable to clear his or her ears, the insertion of myringotomy tubes may be necessary before the treatment continues.

Taken from a 10-year study of 1,505 patients who received 52,758 2-hour HBO treatments at 2.4 ata once or twice daily (The maximum treatment protocol used for problem wounds around the world).

1. Asthma - Small airway hyper-reactivity may result in air trapping and pulmonary barotrauma on ascent. A decision to treat such patients should not be undertaken lightly, particularly in light of evidence that the administration of some bronchodilators may increase the incidence of cerebral arterial gas embolism through pulmonary vasodilation.

2. Congenital spherocytosis - Such patients have fragile red cells and treatment may result in massive haemolysis

3. Cisplatinum - There is some evidence that this drug retards wound healing when combined with HBO.

4. Disulphiram (Antabuse) - There is evidence to suggest that this drug blocks the production of suproxide dismutase and this may severely effect the body's defenses against oxygen free radicals. Experimental evidence suggest that a single exposure to HBO is safe but that subsequent treatments may be unwise.

5. Doxorubicin - (Adriamycin). This chemotherapeutic agent becomes increasingly toxic under pressure and animal studies suggest at least a one week break between last dose and first treatment in the chamber.

6. Emphysema with CO2 retention - Caution should be exercised in giving high pressures + concentrations of oxygen to patients who may be existing on the hypoxic drive to ventilation. Such patients may become apnoeic in the chamber and require IPPV. In addition, gas trapping and subsequent lung rupture are associated with bullous disease.

7. High Fevers - High fevers (>38.5degC) tend to lower the seizure threshold due to O2 toxicity and may result in delaying of relatively routine therapy. If patients are to be treated then attempt should be made to lower their core temperature with antipyretics and physical measures

8. History of middle ear surgery or disorders - These patients may be unable to clear their ears, or risk further injury with vigorous attempts to do so. An ENT consult for possible placement of grommets is usually wise

9. History of seizures - HBO therapy may lower the seizure threshold and some workers advocate increasing the baseline medication for such patients

10. Optic Neuritis - There have been reports in patients with a history of optic neuritis of failing sight and even blindness after HBO therapy. This complaint would seem to be extremely rare but of tragic consequence.

11. Pneumothorax - A pocket of trapped gas in the pleura will decrease in volume on compression and re-expand on surfacing during a cycle of HBO therapy. During oxygen breathing at depth nitrogen will be absorbed from the space and replaced with oxygen. These fluxes of gases and absolute changes in volume may result in further lung damage and or arterial gas embolization. If there is a communication between lung and pneumothorax with a tension component, then a potentially dangerous situation exists as the patient is brought to the surface. As Boyle's Law predicts, a 1.8 litre pneumothorax at 20 msw is potentially a 6 litre pneumothorax at sea level - certainly a life threatening situation. For this reason it is mandatory to place a chest tube to relieve a pneumothorax before contemplating HBO therapy. Particular care must be taken with patients who give a history of chest trauma or thoracic surgery.

12. Pregnancy - The fears that either retrolental fibroplasia or closure of the ductuc arteriosus may result in the fetus whose mother undergoes HBO appear to be groundless from considerable Russian experience. However, HHI continues to exercise caution in limiting treatment of pregnant women to emergency situations.

13. Upper Respiratory Tract Infections - These are relative contra-indications due to the difficulty such patients may have in clearing their ears and sinuses. Elective treatment may be best postponed for a few days in such cases.

14. Viral Infections - Many workers in the past have expressed concern that viral infections may be considerably worsened after HBO. There have been no studies to give convincing evidence of this and no reported activation of herpetic lesions associated with HBO.