[The clinical value of bedside lung ultrasound in the diagnosis of chronic obstructive pulmonary disease and cardiac pulmonary edema].

Objective: To study the diagnostic accuracy of bedside lung ultrasound examination in chronic obstructive pulmonary disease (COPD) and cardiac pulmonary edema.

Methods: A prospective pilot and single-blind trial was conducted. A total of 89 patients with respiratory failure admitted to the Department of Critical Care Medicine of Anhui Provincial Hospital from September 2012 to September 2013 were enrolled. There were 32 patients with COPD, 31 patients with cardiac pulmonary edema, 8 patients with interstitial lung disease, 12 with lung infection, and 6 patients with other diseases. Another group of 30 patients without respiratory disease were enrolled as the control group. Bedside lung ultrasound examinations were performed in all patients within 24 hours, and chest radiograph was performed at the same time. The signs to be revealed were the "A" lines or horizontal lines arising from the pleural line, and the comet-tail artifact ("B" lines) arising from the lung wall interface.

Results: Of 89 patients, 33 patients were shown a mean of 2.94 ± 1.87 "A" lines per case with the bedside lung ultrasound, and 38 patients with a mean of 3.27 ± 1.72 "B" lines per patient. 1.94 ± 0.96 "A" lines a case and 1.74 ± 0.82 "B" lines a case in control group. There were significant difference between the test group and control group ("A"line: t=3.835, P=0.000; "B" line: t=6.540, P=0.000). Among 32 cases with COPD, 28 patients had a positive result of "A" line with a coincidence rate of 81.2%. In the 31 patients with cardiac pulmonary edema, 25 patients presented "B" line, with a coincidence rate of 80.6%. The "A" lines or horizontal lines arising from the pleural line showed a sensitivity of 81.30% and a specificity of 87.70% with a positive predictive value (PPV) 78.80% and a negative predictive value (NPV) 89.30% of in the diagnosis of COPD, and the "B" lines showed a sensitivity of 80.60% and a specificity of 77.60% with a PPV of 65.80% and a NPV of 88.20% in the diagnosis of cardiac pulmonary edema. However, X-ray examination showed a sensitivity of 65.50%, a specificity of 86.00%, a PPV of 72.40% and a NPV of 81.70% in the diagnosis of COPD, and it showed a sensitivity of 74.20%, a specificity of 69.00%, a PPV of 56.10% and a NPV of 83.30% in the diagnosis of cardiac pulmonary edema. Bedside ultrasound was highly consistent with X-ray in diagnosis of COPD [area under receiver operating characteristic curve (AUC): 0.833 vs. 0.816, P>0.05], but Kappa value of ultrasound technology "A" line in the diagnosis of COPD was greater than the value of X-ray imaging techniques (0.685 vs. 0.527). There was little diagnostic value of ultrasound "A" line in cardiac pulmonary edema(AUC was 0.305), while the "B" line was superior to X-ray (AUC: 0.888 vs. 0.747, P<0.001), and had a higher Kappa value than the value of X-ray imaging techniques (0.553 vs. 0.481) in cardiac pulmonary edema.

Conclusions: We conclude that bedside ultrasound is cost-effective, easy for repeated examination, and suitable for differential diagnosis of lung diseases. It might be useful in screening for COPD and cardiac pulmonary edema.