Increase in venous [K+] During Hyperbaric Exposure Independent of Changes in pH or O2 Concentration

Plasma potassium regulation is important for function of numerous cells in the body. Changes in potassium levels during exposure to an increased O2 concentration is thought to be the result of the changes in pH and increasing reactive oxygen species. However, the effects of hyperbaria on plasma potassium concentration are not well understood. Methods Eight subjects were exposed to 1.3 atmospheres absolute (ATA) of hyperbaric air for 90 minutes, 10‐times (M‐F) over 12‐days. Another eight subjects were exposed to 100% oxygen at 1 ATA over the same interval. Four venous blood draws were taken. On day 1 the first draw was taken immediately preceding treatment and the second was taken immediately following treatment. The third draw was taken prior to the 10th treatment and the 4th draw was taken 72 hours post final treatment. We analyzed samples on a blood gas analyzer and performed statistical analysis using a paired Wilcoxon signed‐rank test. Results The concentration group saw strong trend towards an increase in the potassium concentration from 4.09 ± 0.12 (mmol/L) to 4.28 ± 0.28 (mmol/L) (p = 0.065). In the hyperbaric group we see a significant increase in potassium concentration from 4.19 ± 0.26 (mmol/L) to 4.55 ± 0.27 (mmol/L) (p = 0.0068). In the concentration group we also see a significant increase in pH concentration from 7.37 ± 0.03 to 7.39 ± 0.01 (p= 0.021). A similar significant increase is not seen in the hyperbaric group. Summary These finding suggest that changes in potassium concentration in response to hyperbaria are not the result of oxygen concentration nor pH. Possible explanations include increased nitrogen levels due to hyperbaric air, increased CO2 concentration in hyperbaric chamber or changes in the activity of Na+,K+ ATPase pumps at the cellular level which may be a homeostatic response to combat pulmonary edema