THEORETICAL ASSESSMENT OF NORMOBARIC OXYGEN-THERAPY TO TREAT PNEUMOCEPHALUS - RECOMMENDATIONS FOR DOSE AND DURATION OF TREATMENT

Background: Pneumocephalus has been linked to several clinical conditi ons, including headache, lethargy, and even brain herniation or death. The effects of different normobaric oxygen concentrations and duratio ns of therapy on the rate of air absorption were examined. Methods: An existing mathematical model of inert gas absorption was used. The mod el accounts for the major phenomena that determine absorption of bubbl es, including surface tension, pressure dependence of bubble size, and removal of gases to the surrounding tissue. Sensitivity analysis test ed reliability of our results. Results: Times for a 50-ml air collecti on to have been absorbed were 5.8, 1.9, and 0.6 weeks at an FIo2, of 0 .21, 0.4, and 1.0, respectively. Thirty percent and 72% of the air was absorbed in 2 days at an FIo2, of 0.4 and 1.0, respectively. The perc ent decrease in time for absorption achieved by increasing the FIo2, f rom 0.21 was nearly identical for different volumes of air. The benefi t of increasing the FIo2, decreased with progressive increases in the FIo2. Increasing the FIo2, from 0.21 to 0.4 caused the time to total a ir absorption to decrease by 67%. In contrast, increasing the FIo2 fro m 0.8 to 1.0 caused the time to total air absorption to decrease by an additional 3%. Conclusions: Based on mathematical model predictions, an FIo2, of 0.4 or 1.0 for at least 1 week or 2 days, respectively, wi ll significantly decrease the time for absorption of a pneumocephalus.