Effect of inspiratory resistance and PEEP on /sup 99m/Tc-DTPA clearance
Experiments were performed to determine the effect of markedly negative pleural pressure (Ppl) or positive end-expiratory pressure (PEEP) on the pulmonary clearance (k) of technetium-99m-labeled diethylenetriaminepentaacetic acid (/sup 99m/Tc-DTPA). A submicronic aerosol containing /sup 99m/Tc-DTPA was insufflated into the lungs of anesthetized intubated sheep. In six experiments k was 0.44 +/- 0.46% (SD)/min during the initial 30 min and was unchanged during the subsequent 30-min interval (k = 0.21 +/- 12%/min) when there was markedly increased inspiratory resistance. A 3-mm-diam orifice in the inspiratory tubing created the resistance. It resulted on average in a 13-cmH2O decrease in inspiratory Ppl. In eight additional experiments sheep were exposed to 2, 10, and 15 cmH2O PEEP (20 min at each level). During 2 cmH2O PEEP k = 0.47 +/- 0.15%/min, and clearance increased slightly at 10 cmH2O PEEP (0.76 +/- 0.28%/min, P less than 0.01). When PEEP was increased to 15 cmH2O a marked increase in clearance occurred (k = 1.95 +/- 1.08%/min, P less than 0.001). The experiments demonstrate that markedly negative inspiratory pressures do not accelerate the clearance of /sup 99m/Tc-DTPA from normal lungs. The effect of PEEP on k is nonlinear, with large effects being seen only with very large increases in PEEP.
- Research Organization:
- McMaster Univ. Health Sciences Centre, Hamilton, Ontario
- OSTI ID:
- 5204406
- Journal Information:
- J. Appl. Physiol.; (United States), Vol. 5
- Country of Publication:
- United States
- Language:
- English
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LABELLED COMPOUNDS
SHEEP
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