Spontaneous breathing affects the spatial ventilation and perfusion distribution during mechanical ventilatory support*
| Autor: | Christian Putensen, Lars G. Andersson, José Hinz, Hermann Wrigge, Enn Maripuu, Jörg Zinserling, Göran Hedenstierna, Peter J. Neumann |
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| Rok vydání: | 2005 |
| Předmět: |
Pulmonary Circulation
genetic structures Swine medicine.medical_treatment Blood Pressure Critical Care and Intensive Care Medicine Ventilation/perfusion ratio Airway pressure release ventilation Intensive care Ventilation-Perfusion Ratio medicine Animals Continuous positive airway pressure Radionuclide Imaging Mechanical ventilation Respiratory Distress Syndrome Continuous Positive Airway Pressure Respiratory distress Pulmonary Gas Exchange business.industry Respiration Respiratory disease respiratory system medicine.disease Anesthesia Breathing business |
| Zdroj: | Critical Care Medicine. 33:1090-1095 |
| ISSN: | 0090-3493 |
| DOI: | 10.1097/01.ccm.0000163226.34868.0a |
| Popis: | In acute respiratory failure, gas exchange improves with spontaneous breathing during airway pressure release ventilation (APRV). The mechanisms for this improvement are not fully clear. We have shown that APRV with spontaneous breathing reopens nonaerated lung tissue in dorsal juxtadiaphragmatic regions. We hypothesized that spontaneous breathing during APRV may redistribute ventilation and perfusion toward these reopened regions.Prospective, randomized, controlled study.Animal research laboratoryTwenty controlled mechanically ventilated pigs.Lung injury was induced by injection of oleic acid into the central circulation; thereafter, pigs were randomized to APRV with or without spontaneous breathing. To induce spontaneous breathing during APRV with spontaneous breathing, the mechanical respiratory rate was decreased by 50% in this group.We measured respiratory mechanics, hemodynamics, gas exchange including the multiple inert gas elimination technique, and the spatial ventilation and perfusion distribution using single photon emission tomography. At similar minute ventilation and airway pressures, shunt remained stable during APRV with spontaneous breathing, whereas it increased during APRV without spontaneous breathing during the 2-hr study period (p = .006). Single photon emission tomography showed more ventilation (p.001) and pulmonary blood (p.025) flow in dorsal, juxtadiaphragmatic lung regions when spontaneous breathing was present.The beneficial effects of spontaneous breathing on intrapulmonary shunt and oxygenation are explained both by increased ventilation of aerated dependent lung tissue and by opening up nonaerated tissue so that ventilation is distributed to a larger share of the lung. Redistribution of perfusion is possibly secondary to the altered ventilation. The overall effect is a more efficient use of available lung tissue for gas exchange. |
| Databáze: | OpenAIRE |
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