Oleic acid-induced pulmonary oedema
High-frequency jet ventilation
Continuous positive pressure ventilation
Springer Online Journal Archives 1860-2000
Abstract In oleci acid-induced pulmonary oedema (OAPO) sequential intrapulmonary fluid accumulation occurs leading to different expiratory flow pattern in dependent lung regions. The potential effects on efficacy of high-frequency jet ventilation (HFJV, f=3 Hz, I: E=0.43, FiO2=0.4) were studied and compared with continous positive pressure ventilation (CPPV, f=12–18/min, I:E=0.5, TV=12 ml/kg, PEEP=0.5 kPa, FiO2=0.4) in a dog model of OAPO. In the control state (lung-healthy dogs), 15 min afteroleic acid lung injury (interstitial oedema, period I) and 60 min after onset of OAPO (alveolar oedema, period II), gas exchange, lung volumes, compliance, resistance and haemodynamics were measured. The course of lung oedema was determined indirectly by means of washout curvesof helium (foreign gas bolus-test, FGB) and nitrogen (single breath-test for oxygen, SBO2). During control, there were no significant differences between the HFJV-group (n=7) and the CPPV-group(n=6) by virtue of gas exchange, lung volumes and haemodynamics. During period I, PaO2 decreased signiicantly both with HFJV (p〈0.01) and CPPV (p〈0.05), being lower in the HFJV-group (p〈0.05). PaCO2, pulmonary and haemodynamic parameters were unchanged. Onset of phase IV of the alveolar plateau (closing volume CV) occurred significantly earlier (p〈0.05) in all animals. Impaired ventilation of dependent lung regions, increased maldistribution of intrapulmonary gas and VA/Q-mismatching may be the underlying mechanisms for lower efficacy of HFJV during interstitial lung oedema. In period II, pulmonary and cardiocirculatory parameters had changed significantly in both groups. CV had decreased, indicating a biphasic behavior of washout curves, which is due to changes of regional FRC, resistance and compliance after onset of alveolar flooding. Oxygenation was significantly more impaired in the HFJV-group (p〈0.05). CPPV is superior to HFJV in maintaining sufficient gas exchange both during interstitial and alveolar oedema in dogs with oleic acid-induced lung injury.
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