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Combined effects of hypoxia, carbon monoxide and impaired pulmonary gas exchange on O 2 transport and aerobic capacity (708.5)
Author(s) -
Crocker George,
Jones James
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.708.5
Subject(s) - carboxyhemoglobin , hypoxia (environmental) , circulatory system , hypoxemia , anesthesia , chemistry , hemoglobin , oxygen , medicine , carbon monoxide , biochemistry , organic chemistry , catalysis
This study determined how three factors interact to limit cardiopulmonary O 2 delivery, O 2 extraction and maximal aerobic capacity ( V O 2max ): 1) breathing hypoxic gas; 2) impairing pulmonary gas exchange; and 3) reducing circulatory capacitance for O 2 . Five goats ran on a treadmill at V O 2max following oleic‐acid induced acute lung injury ( ALI ) or with no lung injury ( NLI ). Goats breathed normoxic or hypoxic inspired gas fractions ( F I O 2 0.21 or 0.12) with and without small amounts of CO to maintain carboxyhemoglobin fractions ( F HbCO ) of 0.02 or 0.30. Hypoxia and ALI induced hypoxemia and reduced O 2 delivery by different mechanisms: hypoxia reduced alveolar O 2 partial pressure ( P O 2 ), whereas, ALI increased alveolar‐arterial P O 2 difference. Elevated F HbCO lowered O 2 delivery by reducing circulatory capacitance for O 2 and reduced O 2 extraction by increasing hemoglobin ( Hb ) affinity for O 2 . All combinations of hypoxia, ALI and elevated F HbCO attenuated the reduction in V O 2max compared to the sum of each treatment’s individual effects on V O 2max when administered separately. Hypoxia and ALI administered in combination attenuated the reduction in O 2 delivery without affecting O 2 extraction. Elevated F HbCO and ALI attenuated the decrease in O 2 delivery because increased arterial O 2 saturation partially compensated for reduced circulatory capacitance. The addition of ALI to the combination of hypoxic gas and elevated F HbCO attenuated the decrease in V O 2max because the decrease in O 2 delivery was attenuated and O 2 extraction synergistically increased. Results from this study are applicable to individuals, e.g ., soldiers, rescue workers and miners, that experience traumatic lung injury while breathing hypoxic and CO‐containing gases associated with fires. Grant Funding Source : Supported by U.S. Army Medical Research and Materiel Command with L‐3 Communications/Jaycor.