Normalizing CO2 in chronic hyperventilation by means of a novel breathing mask: a pilot study


  • Authorship and contributorship

    Troels Johansen: designed and performed study, analyzed data, cowrote article

    Sandy Jack: contributed to design of study and analysis of data, cowrote article

    Ronald Dahl: contributed to design of study and analysis of data, cowrote article

  • Ethics

    The study was performed in accordance with the 2000 Declaration of Helsinki and was approved by the Ethics Committee of Central Jutland and the Danish Health and Medicines Authority. All patients gave their informed consent prior to their inclusion in the study.

  • Conflicts of interest

    Sandy Jack declares to have no conflicts of interest. Ronald Dahl declares to have no conflicts of interest. Troels Johansen is a shareholder in, and the CEO of, Balancair ApS, the company that has applied for a patent on the mask technology. The work as CEO is unsalaried, and the company has no employees.

    The study has been registered in the US National Library of Medicine registry (, with the identifier NCT01575665.



Chronic idiopathic hyperventilation (CIH) is a form of dysfunctional breathing that has proven hard to treat effectively.


To perform a preliminary test of the hypothesis that by periodically inducing normocapnia over several weeks, it would be possible to raise the normal resting level of CO2 and achieve a reduction of symptoms.


Six CIH patients were treated 2 h a day for 4 weeks with a novel breathing mask. The mask was used to induce normocapnia in these chronically hypocapnic patients. Capillary blood gases and acid/base parameters [capillary CO2 tension (PcapCO2), pH, and standard base excess (SBE)] were measured at baseline and once each week at least 3 h after mask use, as well as spirometric values, breath-holding tolerance and hyperventilation symptoms as per the Nijmegen Questionnaire (NQ).


The mask treatment resulted in a significant increase of resting PcapCO2 (+0.45 kPa, P = 0.028), a moderate increase in SBE (+1.4 mEq/L, P = 0.035) and a small reduction in daily symptoms (−3.8 NQ units, P = 0.046). The effect was most pronounced in the first 2 weeks of treatment.


By inducing normocapnia with the breathing mask 2 h a day for 4 weeks, the normal resting CO2 and acid/base levels in chronically hyperventilating patients were partially corrected, and symptoms were reduced.