We have recently developed a noninvasive dimethylether (DME) uptake technique to estimate airway mucosal blood flow (Q̇aw) in humans (12). Because it was not feasible to validate the technique directly, we undertook the present study to compare Q̇aw as measured by DME (Q̇(DMK)) and by color-coded microspheres (Q̇(M)) as a standard in seven anesthetized sheep prepared with a carotid and a left atrial catheter. Q̇(DME) was determined by measuring DME uptake with multiple breath holds after passive inflation with a DME-helium gas mixture, simulating the technique used in humans. After the microspheres were injected into the left atrium, the sheep were killed and the tracheal segment corresponding to the dead space from which DME uptake was determined was removed, and its mucosa was stripped and processed for microsphere counts. Mean Q̇(DME) was 35.6 ml · min-1 · 100 g-1 wet tissue (range 9.6-98.0 ml · min-1 · 100 g-1) and mean Q̇(M) was 29.1 ml · min-1 · 100 g-1 (range 7.7-91.5 ml · min-1 · 100 g-1). There was a strong correlation between Q̇(DME) and Q̇(M) (r = 0.89; P = 0.01). Intravenous nitroglycerin and vasopressin caused comparable increases and/or decreases in Q̇(DME) and Q̇(M) (r = 0.87; P = 0.02). This suggests that the noninvasive DME uptake method measures Q̇aw accurately and supports its validity in human studies.
- airway blood flow
ASJC Scopus subject areas
- Orthopedics and Sports Medicine
- Physical Therapy, Sports Therapy and Rehabilitation