Effects of a standard hyperbaric oxygen treatment protocol on pulmonary function
European Respiratory Journal
Recompression and hyperbaric oxygen (HBO) are used in the treatment for diving-related diseases such as decompression sickness and arterial gas embolism. For a long time HBO has also been shown to be effective in carbon monoxide poisoning and anaerobic infections. More recently, HBO has been shown to have supplementary effects in the treatment of other disorders characterized by local ischaemia. An increase in local oxygen supply due to an increased gradient for diffusion is achieved by
... achieved by increasing the partial pressure of oxygen (PO 2 ) in inspired gas. This results in local stimulation of fibroblast proliferation and collagen synthesis, angiogenesis and enhanced granulocyte function and peroxidase activity in ischaemic tissue. In this way, HBO treatment is an effective adjunct in the treatment of osteoradionecrosis, chronic osteomyelitis, diabetic leg ulcers and radiation-induced proctitis and cystitis. On an experimental basis, HBO treatment is currently evaluated as a supplement in the treatment of several other disorders. Indications for HBO treatment have been worked out by the Undersea and Hyperbaric Society , differentiating between indications where HBO has been shown to have a definite effect based on controlled clinical studies and indications where HBO still has to be considered experimental. In this setting, HBO treatment is usually given for 90 min daily at a PO 2 of 200-280 kPa for 20-30 days. Toxic pulmonary effects of exposure to hyperoxia are well known. There is a dose-dependent reduction in vital capacity with continuous exposure to a PO 2 >50 kPa, as characterized by CLARK and LAMBERTSEN . It has also been shown that this effect is attenuated by intermittent exposure to up to the same cumulative dose of oxygen  and tolerance to the oxidative stress develops. HBO treatment protocols and diving procedures are based on these doseresponse relationships and practical experience. Ser-ious pulmonary oxygen toxicity has not been reported with this form of HBO treatment. However, systematic studies to quantify the effect on pulmonary function of commonly used HBO treatment protocols are lacking. Methods Patients Twenty consecutive patients (10 male) undergoing treatment for ischaemic leg or foot ulcers, chronic osteomyelitis, delayed healing of fractures with pseudarthrosis or pelvic radionecrosis were included in the study. Patients with lung disease, former irradiation of the head, neck or thorax as part of the treatment for the primary disease, current smokers and patients with radiologically abnormal Effects of a standard hyperbaric oxygen treatment protocol on pulmonary function. E. Thorsen, L. Aanderud, T.B. Aasen. ©ERS Journals Ltd 1998. ABSTRACT: The prescription of hyperbaric oxygen (HBO) therapy for disorders not related to diving is increasing. Pulmonary oxygen toxicity is well known, but the effect of the cumulative oxygen exposure corresponding to a standard HBO treatment protocol has not been quantified before. Twenty patients (10 male) had 21 HBO treatments at a partial pressure of oxygen of 240 kPa for 90 min daily. None had any previous lung disease and all had normal chest radiography and lung function at the start of the study. Dynamic lung volumes, forced expiratory flows and the transfer factor of the lung for carbon monoxide (TL,CO) were measured before the HBO treatment, on days 7, 14 and 21 during treatment and then 3-4 weeks after treatment. Four patients (one male) reported nonproductive coughing during the last week of treatment. There was a progressive reduction in forced expiratory volume in one second (FEV1) (p<0.001), mean forced mid-expiratory flow rate (FEF25-75%) (p<0.001) and forced expiratory flows at 50 and 75% of forced vital capacity (FVC) expired during HBO treatment. The reduction in FEV1 on day 21 was 4.4±1.7% and in FEF25-75% 10.3±6.1%. Four weeks after treatment there was a partial normalization. There were no changes in FVC or peak expiratory flow (PEF). TL,CO was slightly reduced on day 21 of treatment only (p<0.01) and fully normalized 1 month later. A reduction in small airways conductance is consistent with other studies where total oxygen exposures have been below the limit causing toxic pulmonary effects traditionally measured as a reduction in vital capacity. This effect is not considered to be of any clinical significance for patients treated with hyperbaric oxygen unless repeated treatment series are to be given.