ABSTRACT.Purpose: The aim of this study was to quantify ocular refractive changes after a standard hyperbaric oxygen (HBO) treatment protocol and to characterize the time period of recovery. Patients and Methods: Hyperbaric oxygen therapy was given for 90 min daily at a pressure of 240 kPa for 21 days. Oxygen was administered to 20 patients using an oronasal mask and to 12 patients using a hood. Follow-up examinations were carried out 2-4 days after treatment, and thereafter regularly for up to 10 weeks in both groups. Refraction was assessed automatically and by the monocular subjective refraction method. A subgroup of nine of the 20 patients to whom oxygen was administered by an oronasal mask underwent a separate eye examination, which included crystalline lens opacity measurements and LOCS III gradings. Results: In the patients given oxygen by mask, there was a significant myopic shift in the mean spherical equivalent, which was largest 2-4 days after treatment. The shift was À 0.55 AE 0.40 D in the right eye and À 0.53 AE 0.42 D in the left eye. In the patients given oxygen by hood, the largest shift was observed after 12-16 days, and was À 1.06 AE 0.52 D in the right eye and À 1.10 AE 0.57 D in the left eye. The refractive changes returned to baseline 6 weeks and 10 weeks after HBO treatment, respectively. No significant changes in crystalline lens transparency were revealed. Conclusions: The myopic shift after HBO therapy recovers within 10 weeks and may be more pronounced when patients are given oxygen using a hood compared with using an oronasal mask.

The pharmacokinetics and tissue concentrations of ceftazidime have been investigated in 8 patients with severe burns (20-80% of body surface area) undergoing skin transplantation 2 to 21 days after injury. Two prophylactic doses of ceftazidime were administered as 1 g i.v. bolus injections with an 8 h interval. Blood, urine, burn blister fluid and tissue were frequently sampled and drug concentrations were analyzed by HPLC. The kinetics of ceftazidime was the same after each dose. In these patients the pharmacokinetics of ceftazidime was greatly altered from that in other patients and there was much interindividual variation. The mean ceftazidime elimination half-life, apparent volume of distribution and total clearance were: 2.7 h, 30.91 (0.38 1.kg-1) and 139 ml.min-1, respectively. A linear correlation was found between creatinine clearance and the renal clearance of the ceftazidime, the mean values being 108 and 95 ml.min-1, respectively. No correlation was found between creatinine clearance and the total clearance of ceftazidime. The mean percentage urine recovery was 69% of the dose. Tissue and burn blister fluid concentrations were above the MIC, and ranged from 40.0 to 3.1 mg.kg-1. A substantial increase in the apparent volume of distribution and non-renal clearance of ceftazidime was observed, probably due to increased capillary permeability and drug loss through the wound surface replacement of prior to surgery and subsequently to lost and blood fluid.

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 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 [1], 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 [2]. It has also been shown that this effect is attenuated by intermittent exposure to up to the same cumulative dose of oxygen [3] 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 PatientsTwenty 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 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.

Body weight (BW) reductions of more than 4 kg have been observed during diving with the open hot water suit, a technique in which heated seawater (SW) continuously floods the skin surface. To test the hypothesis that osmotic effects may be involved in these fluid-loss processes, head-out immersion experiments in 38 degrees C freshwater (FW) and SW for 4 h were performed. Average BW reduction was 2.5 and 1.9 kg in SW and FW head-out immersion, respectively (P < 0.01). Atrial natriuretic peptide increased during the first 30 min of SW immersion (5.6-13.4 pmol/l, P < 0.01) followed by a reduction to 7.6 pmol/l (P < 0.01). This paralleled an initial decrease in aldosterone (from 427 to 306 pmol/l, P < 0.05) followed by an increase to 843 pmol/l (P < 0.01). The effects of temperature on fluid loss were studied in thermoneutral (34.5 degrees C) and 38 degrees C SW for 2 h. In thermoneutral SW, calculated sweat production was negligible (0.05 kg) compared with 1.2 kg in warm SW. We recommend that, if a dive is planned to last for more than 4 h, a mandatory break for fluid intake should be incorporated in the diving regulations.

Mortality among patients suffering from meningococcal septicaemia has reached nearly 50% in parts of northern