Perbedaan Rerata Serta Korelasi Kadar Interleukin-6 Pada Serum Dan Bronchoalveolar Lavage Dalam Hubungannya Dengan Kejadian Gagal Ekstubasi Dan Mortalitas Pasien Pneumonia Berat Di RSUPN Cipto Mangunkusumo = The Mean Differences and Comparison of Interleukin-6 Levels in Serum and Bronchoalveolar Lavage and Their Correlation to Extubation Failure and Mortality of Severe Pneumonia Patient in RSUPN Cipto Mangunkusumo