Intravascular volume loading reversibly decreases airway cross-sectional area.
High-resolution computed tomography was used to directly determine the short-term effects of intravascular volume expansion on airway caliber. The change in airway cross-sectional area caused by intravascular volume expansion (30 ml/kg, Ringer's lactate) was studied in six anesthetized mini-pigs within 5 min. Twenty-five of 27 large airways (diameter, 2.01 to 5.0 mm) demonstrated decreased internal cross-sectional area (10.56 +/- 1.26 vs 8.66 +/- 1.03 mm2, p < 0.001). Twenty of 24 small airways (diameter, 0.75 to 2.0 mm) showed decreased internal cross-sectional area (1.82 +/- 0.16 vs 1.44 +/- 0.16 mm2, p < 0.001). These changes were rapidly (< 6 min) reversed by intravascular volume reduction. The external airway cross-sectional area did not change. These data suggest rapid, reversible bronchial mucosal vascular engorgement as a cause of increased airway resistance in heart failure.
Wetzel
R C
RC
Department of Pediatrics, Anesthesia/Critical Care Medicine, Johns Hopkins Medical Institutions, Baltimore.
Herold
C J
CJ
Zerhouni
E A
EA
Robotham
J L
JL
D000403:Airway Resistance / Q000502:physiology; D000818:Animals; D001810:Blood Volume / Q000502:physiology*; D001980:Bronchi / Q000033:anatomy & histology / Q000502:physiology*; D001995:Bronchography; D006439:Hemodynamics / Q000502:physiology; D008297:Male; D011651:Pulmonary Artery / Q000000981:diagnostic imaging / Q000502:physiology*; D013552:Swine; D013556:Swine, Miniature; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods