TY - JOUR
T1 - Effect of hypoxia on respiratory system impedance in dogs
AU - Simon, B. A.
AU - Zanaboni, P. B.
AU - Nyhan, D. P.
PY - 1997/8
Y1 - 1997/8
N2 - The effects of hypoxia on lung and airway mechanics remain controversial, possibly because of the confounding effects of competing reflexes caused by systemic hypoxemia. We compared the effects of systemic hypoxemia with those of unilateral alveolar hypoxia (with systemic normoxemia) on unilateral respiratory system impedance (Z) in intact, anesthetized dogs. Independent lung ventilation was obtained with a Kottmeier endobronchial tube. Individual left and right respiratory system Z was measured during sinusoidal forcing with 45 ml of volume at frequencies of 0.2-2.1 Hz during control [100% inspired O2 fraction (FI(O2))], systemic hypoxemia (10% FI(O2)), and unilateral alveolar hypoxia (0% FI(O2) to left lung, 100% FI(O2) to right lung). During systemic hypoxemia, there was a mean Z magnitude increase of 18%. This change was entirely attributable to a decrease in the imaginary component of Z; there was no change in the real component of Z. Administration of atropine (0.2 mg/kg) did not block the increase in Z with systemic hypoxemia. In contrast, there was no change in Z in the lung subjected to unilateral alveolar hypoxia. We conclude that alveolar hypoxia has no direct effect on lung mechanical properties in intact dogs. In contrast, systemic hypoxemia does increase lung impedance, apparently through a noncholinergic mechanism.
AB - The effects of hypoxia on lung and airway mechanics remain controversial, possibly because of the confounding effects of competing reflexes caused by systemic hypoxemia. We compared the effects of systemic hypoxemia with those of unilateral alveolar hypoxia (with systemic normoxemia) on unilateral respiratory system impedance (Z) in intact, anesthetized dogs. Independent lung ventilation was obtained with a Kottmeier endobronchial tube. Individual left and right respiratory system Z was measured during sinusoidal forcing with 45 ml of volume at frequencies of 0.2-2.1 Hz during control [100% inspired O2 fraction (FI(O2))], systemic hypoxemia (10% FI(O2)), and unilateral alveolar hypoxia (0% FI(O2) to left lung, 100% FI(O2) to right lung). During systemic hypoxemia, there was a mean Z magnitude increase of 18%. This change was entirely attributable to a decrease in the imaginary component of Z; there was no change in the real component of Z. Administration of atropine (0.2 mg/kg) did not block the increase in Z with systemic hypoxemia. In contrast, there was no change in Z in the lung subjected to unilateral alveolar hypoxia. We conclude that alveolar hypoxia has no direct effect on lung mechanical properties in intact dogs. In contrast, systemic hypoxemia does increase lung impedance, apparently through a noncholinergic mechanism.
KW - Atropine
KW - Compliance
KW - Hypoxemia
KW - Hypoxic pulmonary vasoconstriction
KW - Lung mechanics
KW - Resistance
UR - http://www.scopus.com/inward/record.url?scp=0030846537&partnerID=8YFLogxK
U2 - 10.1152/jappl.1997.83.2.451
DO - 10.1152/jappl.1997.83.2.451
M3 - Article
C2 - 9262440
AN - SCOPUS:0030846537
SN - 8750-7587
VL - 83
SP - 451
EP - 458
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
IS - 2
ER -