Open AccessRates of carbon monoxide elimination in males and females
Author(s) -
Zavorsky Gerald S.,
Tesler Janet,
Rucker Joshua,
Fedorko Ludwik,
Duffin James,
Fisher Joseph A.
Publication year - 2014
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.12237
Subject(s) - carboxyhemoglobin , ventilation (architecture) , medicine , normocapnia , hemoglobin , respiratory minute volume , anesthesia , zoology , arterial blood , hypercapnia , respiratory system , carbon monoxide , chemistry , biology , mechanical engineering , biochemistry , engineering , catalysis
Abstract The purpose of this study was to verify the previously reported shorter half‐time of elimination ( t ½ ) of carbon monoxide ( CO ) in females compared to males. Seventeen healthy subjects (nine men) completed three sessions each, on separate days. For each session, subjects were exposed to CO to raise the carboxyhemoglobin percentage ( COH b) to ~10%; then breathed in random order, either (a) 100% O 2 at poikilocapnia (no CO 2 added), or (b) hyperoxia while maintaining normocapnia using sequential gas delivery, or (c) voluntary hyperpnea at~4x the resting minute ventilation. We measured minute ventilation, hemoglobin concentration [Hb] and COH b at 5 min intervals. The half‐time of reduction of COH b ( t ½ ) was calculated from serial blood samples. The total hemoglobin mass (Hb TOT ) was calculated from [Hb] and estimated blood volume from a nomogram based on gender, height, and weight. The t ½ in the females was consistently shorter than in males in all protocols. This relationship was sustained even after controlling for alveolar ventilation ( P < 0.05), with the largest differences in t ½ between the genders occurring at low alveolar ventilation rates. However, when t ½ was further normalized for Hb TOT , there was no significant difference in t ½ between genders at alveolar ventilation rates between 4 and 40 L/min ( P = 0.24). We conclude that alveolar ventilation and Hb TOT are sufficient to account for a major difference in CO clearance between genders under resting (nonexercising) conditions.