Question Carbogen to prevent oxygen toxicity?

[Nick_Radov]

Have we been using the wrong gas mixes all along? I ran across this article which shows that some oxygen toxicity effects can be prevented by adding a small amount of carbon dioxide to the breathing mix. This was a clinical study done on dry land and I don't know if it has ever been tested on divers. Would that be a promising area for future research? (I am aware of the risks of hypercapnia.)

Hyperoxic Brain Effects Are Normalized by Addition of CO2
Macey PM, Woo MA, Harper RM (2007) Hyperoxic Brain Effects Are Normalized by Addition of CO2. PLOS Medicine 4(5): e173. Hyperoxic Brain Effects Are Normalized by Addition of CO2

 

[Duke Dive Medicine]

Have we been using the wrong gas mixes all along? I ran across this article which shows that some oxygen toxicity effects can be prevented by adding a small amount of carbon dioxide to the breathing mix. This was a clinical study done on dry land and I don't know if it has ever been tested on divers. Would that be a promising area for future research? (I am aware of the risks of hypercapnia.)

Hyperoxic Brain Effects Are Normalized by Addition of CO2
Macey PM, Woo MA, Harper RM (2007) Hyperoxic Brain Effects Are Normalized by Addition of CO2. PLOS Medicine 4(5): e173. Hyperoxic Brain Effects Are Normalized by Addition of CO2

There's a difference between the effects that the authors cite, "...hypocapnia, diminishing cerebral blood flow and hindering oxygen delivery. Hyperoxic delivery induces other systemic changes, including increased plasma insulin and glucagon levels and reduced myocardial contractility and relaxation..." and CNS or pulmonary oxygen toxicity. The vasodilatory mechanism of CO2 that the authors put forth as protective under normobaric conditions is one of the factors that leads to CNS O2 toxicity under <edit: hyperbaric> hyperoxic conditions.

Best regards,
DDM