| Summary: | 碩士 === 國立成功大學 === 臨床醫學研究所 === 96 === Background:
Bronchoalveolar lavage(BAL) can be used for quantitative bacteriological diagnosis in mechanically ventilated patients suspected of lower respiratory tract infection. BAL may lead to changes in respiratory mechanics, including increased airway resistance and decreased lung compliance. However, risk factors leading to these changes remain unknown. The current study tried to identify risk factors contributing to changes in respiratory mechanics following BAL.
Materials and Methods:
Changes in respiratory mechanics were assessed in fifty-six mechanically ventilated patients receiving BAL using interrupter method under volume-cycled, constant flow ventilation.
Results:
Intrinsic PEEP(PEEPi) was found to be significantly correlated with changes in respiratory system resistance and compliance. In patients with significant PEEPi(>1 cmH2O, n=14), maximal resistance(Rmax) before BAL was 22.5 + 5.9 cmH2O/L/S. Rmax increased to 31.6 + 8.5 cmH2O/L/S immediately after BAL, and by the end of 30 minutes, Rmax remained high(28.4 + 7.5 cmH2O/L/S, p<0.001). The changes in minimal resistance(Rmin), delta resistance(△R) followed the trend of Rmax. In patients without significant PEEPi(<1 cmH2O, n=42), Rmax before BAL was 15.5 + 3.5 cmH2O/L/S. Rmax increased to 17.6 + 4.6 cmH2O/L/S immediately after BAL and by the end of 30 minutes, Rmax fell toward the baslein level(16.6 + 4.3 cmH2O/L/S, p<0.001). The changes of Rmin, △R followed the trend of Rmax too. Increase in Rmax, Rmin, △R following BAL were significantly higher in patients with significant PEEPi than those without significant PEEPi throughout the recording period(p<0.001). Respiratory system compliance immediately following BAL was also significantly reduced in patients with significant PEEPi than those without(p<0.001), but this condition waned over 30 minutes.
Conclusion:
Patients with significant PEEPi experienced greater changes in respiratory mechanics than those without. Physicians should be more cautious when performing BAL in such kind of patients.
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