The rise in carboxyhemoglobin from repeated pulmonary diffusing capacity tests

Respir Physiol Neurobiol. 2013 Mar 1;186(1):103-8. doi: 10.1016/j.resp.2013.01.001. Epub 2013 Jan 17.


The purpose of this study determined the rise in carboxyhemoglobin percentage (COHb) from repeated pulmonary diffusing capacity tests using 5 or 10s single breath-hold maneuvers. Five male and four female non-smokers [baseline COHb=1.2 (SD 0.5%)] performed repeated pulmonary diffusing capacity testing on two separate days. The days were randomized to either repeated 10s (0.28% CO), or 5s (0.28% CO, 55ppm NO) breath-hold maneuvers. Twenty-two 5s breath-hold maneuvers, each separated by 4min rest, raised COHb to 11.1 (1.4)% and minimally raised the methemoglobin percentage (METHb) by 0.3 (0.2)% to a value of 0.8 (0.2)%. After the 22nd test, pulmonary diffusing capacity for carbon monoxide (DLCO) was reduced by about 4mL/min/mmHg, equating to a 0.44% increase in COHb per 5s breath-hold maneuver and a concomitant 0.35mL/min/mmHg decrease in DLCO. Pulmonary diffusing capacity for nitric oxide (DLNO) was not altered after 22 tests. On another day, the 10s single breath-hold maneuver increased COHb by 0.64% per test, and reduced DLCO by 0.44mL/min/mmHg per test. In conclusion, 5s breath-hold maneuvers do not appreciably raise METHb or DLNO, and DLCO is only significantly reduced when COHb is at least 6%.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Breath Holding*
  • Carboxyhemoglobin / analysis*
  • Female
  • Humans
  • Male
  • Pulmonary Diffusing Capacity / physiology*
  • Young Adult


  • Carboxyhemoglobin