Pulmonary responses to overventilation in late multiple organ failure.
BACKGROUND
Patients with multiple organ failure (MOF) require mechanical ventilation for several days. The enormous significance of the ventilation strategy for the outcome of these patients is well appreciated. However, most studies have focused on the onset and the early phase of MOF. It was the aim of the current study to investigate the effect of ventilation in the course of MOF.


METHODS
Using a model where mice develop MOF 7-14 days after intraperitoneal injection of zymosan, the authors analyzed lung functions, signaling pathways, and mediator release in response to protective ventilation (end-expiratory pressure -3 cm H2O; end-inspiratory pressure -10 cm H2O) and overventilation (-22.5 cm H2O) in isolated lungs ex vivo.


RESULTS
On day 7, pulmonary compliance, pulmonary resistance, and tidal volume were normal, but vascular resistance was elevated compared with untreated animals. During ex vivo ventilation, these lungs showed enhanced nuclear factor-kappaB activation, Akt kinase phosphorylation, and cytokine release, and this was further aggravated by overventilation. After 14 days, zymosan-treated animals were characterized by pulmonary hypertension, reduced tidal volume, elevated pulmonary resistance, and increased mediator production. However, in these lungs, neither nuclear factor-kappaB activation nor cytokine production where enhanced by overventilation.


CONCLUSIONS
The zymosan model is characterized by pulmonary inflammation, diminished lung functions, and chronic hypertension. Mechanical ventilation with high distending pressures further augmented cytokine production in this chronic model of MOF only if it significantly augmented tidal volume. The authors speculate that these findings may be explained on the basis of different degrees of lung stretch.
Uhlig
Ulrike
U
Division of Pulmonary Pharmacology, Research Center Borstel, Borstel, Germany. suhlig@ukaachen.de
Drömann
Daniel
D
Goldmann
Torsten
T
Dombrowsky
Heike
H
Vollmer
Ekkehard
E
Zabel
Peter
P
Uhlig
Stefan
S
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D016207:Cytokines / Q000378:metabolism; D066298:In Vitro Techniques; D008168:Lung / Q000473:pathology / Q000503:physiopathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009102:Multiple Organ Failure / Q000473:pathology / Q000503:physiopathology*; D009504:Neutrophils / Q000473:pathology; D051058:Oncogene Protein v-akt / Q000378:metabolism; D010477:Perfusion; D012121:Respiration, Artificial / Q000009:adverse effects*; D012129:Respiratory Function Tests; D015398:Signal Transduction / Q000502:physiology; D015919:Ventilators, Negative-Pressure
D016207:Cytokines; D051058:Oncogene Protein v-akt