We thank Drs. Hampson and Holm for commenting on our Views & Reviews article. [1] It is
true that PaO2 was not measured in the published studies and assumptions were made
regarding normal metabolism and pulmonary function of the study participants. This was a
valid assumption, as all participants were cleared to be placed inside a pressure vessel
and not excluded due to pulmonary or metabolic dysfunctions.
Drs. Hampson and Holm point out an important issue raised by other researchers,
including Dr. Wolf: [2] "partial pressure of oxygen breathed x minutes in hyperbaric
exposure x number of treatments" may turn out to be a more accurate measure of the effects
of hyperbaria on total improvement. However, the effects of pressurized air, even
accounting for the difference in time (300 minutes more in the Wolf et al. study vs all
other studies compared) [1] demonstrate an improvement that is greater than pressurized
pure oxygen for RPQ values. The effect does not vanish, although reduced, when total
exposure time is included. The correlation is valid. The pertinent point is that
pressurized air is a biologically active agent, rendering the conclusions of inactivity or
placebo effect in HBOT/TBI studies questionable.
2. Wolf EG, Baugh LM, Kabban CM, Richards MP, Prye J. Cognitive function in a
traumatic brain injury hyperbaric oxygen randomized trial. Undersea Hyperb Med
2015;42:313-332.
For disclosures, please contact the editorial office at journal@neurology.org.
We thank Drs. Hampson and Holm for commenting on our Views & Reviews article. [1] It is true that PaO2 was not measured in the published studies and assumptions were made regarding normal metabolism and pulmonary function of the study participants. This was a valid assumption, as all participants were cleared to be placed inside a pressure vessel and not excluded due to pulmonary or metabolic dysfunctions.
Drs. Hampson and Holm point out an important issue raised by other researchers, including Dr. Wolf: [2] "partial pressure of oxygen breathed x minutes in hyperbaric exposure x number of treatments" may turn out to be a more accurate measure of the effects of hyperbaria on total improvement. However, the effects of pressurized air, even accounting for the difference in time (300 minutes more in the Wolf et al. study vs all other studies compared) [1] demonstrate an improvement that is greater than pressurized pure oxygen for RPQ values. The effect does not vanish, although reduced, when total exposure time is included. The correlation is valid. The pertinent point is that pressurized air is a biologically active agent, rendering the conclusions of inactivity or placebo effect in HBOT/TBI studies questionable.
1. Figueroa XA, Wright JK. Hyperbaric oxygen: B-level evidence in hyperbaric oxygen therapy trials. Neurology 2016;87:1400-1406.
2. Wolf EG, Baugh LM, Kabban CM, Richards MP, Prye J. Cognitive function in a traumatic brain injury hyperbaric oxygen randomized trial. Undersea Hyperb Med 2015;42:313-332.
For disclosures, please contact the editorial office at journal@neurology.org.