Effect of hyperbaric oxygen on the blood: cerebrospinal fluid transfer of tobramycin

The blood:cerebrospinal fluid (CSF) transfer of the aminoglycoside antibiotic, tobramycin (TOB) was assessed in rabbits. The CSF:blood ratio of TOB, 90 min after a subcutaneous injection, was approximately 1:100 as measured by an agar disc diffusion bioassay. Hyperbaric oxygen therapy at a pressure of 3 ATA caused a slight, non-significant, increase in this ratio, while high dose carbon dioxide, a treatment known to damage the blood:brain barrier, more than doubled this ratio. Thus, hyperbaric oxygen has no significant effect on CSF concentration of TOB in rabbits with intact meninges.