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Influence of acute graded hypoxia on the bronchial circulation in healthy humans
Author(s) -
Ceridon Maile L,
Snyder Eric M,
Olson Thomas P,
Hulsebus Minelle L,
Johnson Bruce D
Publication year - 2008
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.22.1_supplement.1150.15
Subject(s) - hyperventilation , normocapnia , hypocapnia , hypoxia (environmental) , ventilation (architecture) , anesthesia , medicine , arterial blood , airway resistance , cardiac output , cardiology , hypercapnia , chemistry , airway , hemodynamics , respiratory system , oxygen , mechanical engineering , organic chemistry , engineering
Reduced partial pressures of inspired O 2 may influence the bronchial circulation through a number of mechanisms (e.g. altered pulmonary and systemic vascular pressures, lung fluid regulation, airway cooling & drying from increased ventilation). The present study examined the impact of acute, graded hypoxia on bronchial blood flow (Q aw ) in eight healthy adults (28 ± 9 years). Subjects were exposed to inspired O 2 levels resulting in arterial O 2 saturation (SaO 2 ) values of 90% and 80% for 15 min each. To control for the mild hyperventilation that accompanies hypoxia, subjects then mimicked the 80% SaO 2 ventilation (V E ) rate with 21% FIO 2 and again with CO 2 added to the inspirate to maintain normocapnia. Q aw and cardiac output (CO) were measured using soluble gas techniques. Also measured were alveolar‐capillary conductance (D m , index of lung fluid balance), pulmonary capillary blood volume (V c ), and systemic mean (MAP) and pulmonary arterial pressures (PAP). Hypoxia resulted in minimal change in MAP, a small rise in PAP, minimal change in CO and V c , and a rise in D m . There was also a non significant decrease in Q aw with hypoxia. Mild hyperventilation resulted in a significant fall in Q aw , but when normocapnia was maintained, Q aw returned to baseline values. These data suggest that acute, graded hypoxic exposure does not significantly impact Q aw , however, the hypocapnia associated with mild hyperventilation reduces Q aw .