Der Einfluss von spontanen Atemexkursionen unter druckunterstützter Spontanatmung auf Hämodynamik, Gasaustausch und pulmonale Ventilations-Perfusions-Verteilung beim induzierten akuten Lungenversagen

The acute lung injury can be regarded as an imbalance in gas exchange caused by atelectasis and right-left shunt. Therefore the main objective of a ventilation strategy is the recruitment of atelectasis in order to improve gas exchange and reduce right-left shunt. There is a high risk of baro- and volutrauma if using high airway pressures for recruiting atelectatic lung areas. Thus, a protective ventilation strategy resulting in low tidal volumes of 4-6 ml/kg, peak airway pressures of 35 cm H2O and a PEEP between 5 and 20 cm H2O is important. The choice of the ideal PEEP depends on the best possible gas exchange parameters, respectively on the pressure-volume-curve of the lung. However, spontaneous breathing patterns like BIPAP also show recruitment of atelectasis and improvement of gas exchange by means of active contractions of the diaphragm. It is not much known about the interactions of PEEP and spontaneous breathing. This interaction is the subject of the present study. Acute lung injury was induced at twenty female pigs by means of a broncho-alveolar lavage with sodium chloride. Afterwards, the pigs were ventilated for twelve hours with Pressure Support Ventilation (PSV) with a PEEP of 5 respectively 10 cm H2O. The influence of PEEP on hemodynamic parameters, gas exchange and ventilation-perfusion distribution was examined. In order to calculate the ventilation- perfusion distribution the multiple inert gas elimination method (MIGET) was used. In the group ventilated with a PEEP of 10 cm H2O a significant improvement of PaO2 and normal Va/Q and a significant reduction of right-left shunt could be observed. There was no improvement of the monitored parameters in the group ventilated with a PEEP of 5 cm H2O. In the PEEP 5 group the mortality rate was significantly higher. Hemodynamic parameters were not affected in both groups. The main cause for arterial hypoxia was a mismatch of ventilation and perfusion indicated by an increase of right-left shunt, lowVa/Q and log SD Q. A PEEP of 10 cm H2O caused a recruitment of atelectasis, a reduction of right-left shunt and a more homogeneous gas exchange. The increase of normally ventilated and perfused lung areas resulted in an improvement of PaO2. This investigation has shown that the application of PEEP under PSV improves gas exchange and ventilation-perfusion distribution and reduces atelectasis. This effect of PEEP could only be observed with a PEEP of 10 cm H2O, but not with a PEEP of 5 cm H2O. Spontaneous breathing excursions under PSV cannot replace PEEP in order to improve gas exchange and ventilation- perfusion distribution.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2004

Author dc:creator

• Scholl, Katja Iris

Contributors dc:contributor

• Kuhlen, Ralf

• info:eu-repo/classification/ddc/610
• Medizin
• ARDS
• Pressure support ventilation
• MIGET
• PEEP

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123587%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:61986