Relative contraindications, to which special consideration must be given by specialist physicians before treatments, include:
- Upper respiratory infection – This may make it difficult for the patient to clear the ears and can result in sinus squeeze.
- Chronic sinusitis
- Seizure disorders
- Emphysema with CO2 retention – This can lead to pneumothorax during treatment.
- Uncontrolled high fever – This can predispose the patient to oxygen seizures.
- Malignant disease – Cancers thrive in blood-rich environments, but also may be suppressed by high oxygen levels. HBO both increases blood flow and raises oxygen levels. Taking an anti-angiogenic supplement may provide a solution. A recent NIH funded study on stem cells indicate that HBO is actually beneficial in producing stem/progenitor cells and the malignant process is not accelerated so this contraindication remains highly controversial.
- History of spontaneous pneumothorax
- History of thoracic (chest) surgery – Not usually a problem and rarely a contraindication; however, there is concern that air might be trapped in lesions created by surgical scarring. This possibility needs to be evaluated prior to considering HBOT.
- History of reconstructive ear surgery – Ear surgery may be a contraindication and a consultation with an ENT doctor is suggested. A tube could be placed through the eardrum to avoid problems.
- Pulmonary lesions on routine x-ray of CT scan
- Viral infection
- Congenital spherocytosis – In congenital shperocytosis the red blood cells are extremely fragile and hemolysis may follow HBOT. The patient may be carefully monitored and adequate nutritional supplementation is provided.
- Sickle cell anemia – Patients with sickle cell are well known for seizures from oxygen toxicity. They have chronic hemolysis and turnover of hemoglobin and frequently have carboxyhemoglobin levels (in the absence of an external CO source).
- History of optic neuritis – Blindness associated with HBOT in patients with a history of optic neuritis is rare and anecdotal. One apocryphal report, bandied about in the literature, describes a woman being treated for MS who went completely blind during a course of HBOT and remained so. In fact, patients with MS frequently have visual symptoms, including blindness. Treatment should be immediately stopped at the slightest symptoms of visual changes related to the retina. Some HBOT facilities insist on an ophthalmologist’s examination before multiple treatments are initiated.
- In some patients with Chronic Obstructive Pulmonary Disorder (COPD), emphysema, chronic bronchitis and CO2 retention, care must be taken and intubation may be considered.
Risks have been seen to vary from individual to individual depending on age, weight, gender, and even between treatments for the same individual due to circadian rhythms, drug intake and vitamins, etc.
Fish oil supplementation may increase the risk of bleeding, and may compromise some immune system-based therapies that may be used in conjunction with HBOT. DHA (one of the fatty acids found in fish oils) enhances the toxic action of chemotherapeutic agents.30
Elevated production of oxygen free radicals and peroxidation products has been seen in patients taking fish oil. These damaging chemicals are thought to be elevated by HBOT as well.31