2004 Fiscal Year Final Research Report Summary
Optimal ventilatory settings during high frequency oscillatory ventilation in the viewpoint of lung protection in a lung injured-rat model
| Project/Area Number |
15591627
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Anesthesiology/Resuscitation studies
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| Research Institution | Osaka University |
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Principal Investigator |
FUJINO Yuji Osaka University, Hospital, Lecturer, 医学部附属病院, 講師 (50252672)
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| Co-Investigator(Kenkyū-buntansha) |
UCHIYAMA Akinori Osaka University, Hospital, Assistant Professor, 医学部附属病院, 助手 (00324856)
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| Project Period (FY) |
2003 – 2004
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| Keywords | acute respiratory failure / mechanical ventilation / high frequency oscillation |
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| Research Abstract |
We developed a high-frequency oscillator for animal research. Basic mechanism is that a diaphragm in the oscillator is driven by the pressure produced by the to-and-fro jet. We tested this oscillator in the normal lung rats (n=5). As a result the animals could be ventilated with frequencies ranged from 5 to 40 Hz although tidal volume decreased as frequency increased. Airway pressure swing produced by this oscillator was 50% greater than the commercially available oscillator (Metran Humming V) at 15 Hz.
Then we investigated the effect of frequency on lung injury. Lung injury was induced by ventilating animals with high airway pressure of 38 cm H_2O. This injurious ventilation was performed until PaO_2 decreased below 200 mmHg at fraction of inspiratory oxygen of 100%. Then animals were randomly divided into two groups (5 Hz and 30 Hz). Both groups were oscillated at mean airway pressure of 15 cmH_2O for 4 hours and airway pressure swings were titrated to maintain normocapnia. Mean PaO_2 at 4 hours were 410 mmHg with 5 Hz and 200 mmHg with 30 Hz. Mean tidal volumes were 0.79 mL with 5 Hz and 0.29 mL with 30 Hz.
In addition we evaluated the effect of PaCO_2 during high frequency oscillation. Lung injury was induced by the instillation of hydrochloric acid. Two groups randomly assigned were compared. Target PaCO_2 was 40 mmHg in one group and 80 mmHg in the other. There were no statistical differences in blood gas data except for PaCO_2, lung histology and inflammatory cytokines between groups.
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