PRESSURE-FLOW BEHAVIOR OF A BRONCIIO-PLEURAL FISTULA DURING MECHANICAL VENTILATION
In: Pediatric Research, Jg. 21 (1987-04-01), Heft 4, S. 200A
Online
serialPeriodical
Zugriff:
For a broncho-pleural fistula to resolve, the impedance of the fistulous pathway must increase until flow ceases and the leak seals. We examined the effect of ventilatory pattern on bronchopleural pathway impedance in 7 anesthetized, paralyzed 6-week old lambs. A wedge of subpleural lung tissue was removed and a peripheral bronchus (ID < 1mm) sectioned to create an artificial broncho-pleural pathway. We estimated the pathway's average impedance (Z) from the mean pressures in a regional bronchus measured with a retrograde catheter (Pbr) and at the pleural inlet of the chest tube draining the pleural space (Pout), and the mean flow through the chest tube (Vleak) as Z = (Pbr-Pout)/Vleak. Tidal volume (VT) was measured with a jacket plethysmpgraph calibrated in absolute volume by He dilution. We determined Z while ventilating the lungs with rates of 20, 40, 60, and 80 breath/min and inspiratory times of 1.0, 0.6, 0.3, and 0.2 s. FRC, VT, and mean lung volume were first kept constant at 40, 5, and 2.5 ml/kg. In a second experiment, VTwas adjusted to maintain PACO2constant, without changing FRC or mean volume. Z ranged from 0.172 to 5.930 cm H2O/ml/s and was independent of ventilatory rate even when VTwas increased. Repeated stepwise inflation/deflation maneuvers revealed a biphasic static Z-Iung volume relationship, with Z decreasing at low volumes and increasing slowly at volumes greater than FRC. Our results indicate that Z is 1) unaffected by ventilatory pattern at conventional ventilatory rates and 2) sensitive to lung volume only at low volumes. At high lung volumes, peribronchial pressures may exceed the pressure inside the fistula, thus creating a choking effect which increases Z. The same effect may occur if Poutis lowered by applying negative pleural pressure.
Titel: |
PRESSURE-FLOW BEHAVIOR OF A BRONCIIO-PLEURAL FISTULA DURING MECHANICAL VENTILATION
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Autor/in / Beteiligte Person: | Fontán, Julio Perez ; Rav, Andrea O |
Link: | |
Zeitschrift: | Pediatric Research, Jg. 21 (1987-04-01), Heft 4, S. 200A |
Veröffentlichung: | 1987 |
Medientyp: | serialPeriodical |
ISSN: | 0031-3998 (print) ; 1530-0447 (print) |
DOI: | 10.1203/00006450-198704010-00201 |
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