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Biomedical subjects

J R Rodarte

Publications and source records attributed to J R Rodarte.

115 records · Page 7Linked to original sources
PubMed1975

Influence of expiratory flow on closing capacity at low expiratory flow rates.

Single-breath oxygen (SBO2) tests at expiratory flow rates of 0.2, 0.5, and 1.01/s were performed by 10 normal subjects in a body plethysmograph. Closing capacity (CC)--the absolute lung volume at which phase IV began--increased significantly with increases in flow. Five subjects were restudied with a 200-ml bolus of 100% N2 inspired from residual volume after N2 washout by breathing 100% O2 and similar results were obtained. An additional five subjects performed SBO2 tests in the standing, supine, and prone positions; closing volume (CV)--the lung volume above residual volume at which phase IV began--also increased with increases of expiratory flow. The observed increase in CC with increasing flow did not appear to result from dependent lung regions reaching some critical "closing volume" at a higher overall lung volume. In normal subjects, the phase IV increase in NI concentration may be caused by the asynchronous onset of flow limitation occurring initially in dependent regions.

Adult↗
PubMed1975

Effect of increased static lung recoil on bronchial dimesions of excised lungs.

We measured bronchial diameters and lengths during static deflation and inflation in eight excised dog lobes before and after static lung recoil (Pst(L)) had been significantly increased by cooling the lobe for 48 h at 4 degrees C and ventilating it for 3 h. In control lobes, bronchial diameters were the same at any volume even though Pst(L) was different during inflation and deflation. These results agree with those of Hughes et al. (J. Appl. Physiol. 32: 25-35, 1972). However, when Pst(L) was increased, diameters at a given volume were significantly increased over control values; diameters at a given pressure were nearly the same as the controls. Therefore, under these conditions, bronchial diameter did not conform to lung volume. The ventilation process appeared to alter the circumferential elastic properties of the bronchi because diameters at all pressures were slightly larger after ventilation. Bronchial length-volume relationships were the same in both control and ventilated lobes. Thus, when Pst(L) was markedly increased, diameter corresponded best to lung recoil and length to lung volume.

Animals↗
PubMedDate not supplied

Diaphragm dysfunction and respiratory insufficiency after upper abdominal surgery.

This study was designed to determine the contribution of diaphragm dysfunction and pain to respiratory insufficiency after upper abdominal surgery. Respiratory insufficiency and postoperative pain in humans were evaluated by pulse oximetry, pulmonary function tests, and a visual analog scale. Diaphragm shortening in dogs was evaluated with biplane videoroentgenography. In humans, despite reasonable pain control, pulmonary function, as reflected in forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and arterial oxygen saturation (SpO2) were significantly reduced on the first postoperative day. Improved pain control was not associated with improvements in FVC or FEV1. In the dogs, diaphragm shortening and tidal volume were significantly reduced in the immediate postoperative period. Phrenic nerve stimulation immediately after surgery resulted in supramaximal diaphragm shortening, which indicated neither the diaphragm nor phrenic nerves were significantly injured by surgical manipulation. Diaphragm dysfunction has a major role in postoperative pulmonary insufficiency; an afferent-mediated reflex inhibition of the phrenic nerves may be responsible.

Abdomen↗