Effects of the nasal passage on forced oscillation lung function measurements.

The forced oscillation technique (FOT) is a non-invasive pulmonary function test which is based on the measurement of respiratory impedance. Recently, promising results were obtained by the application of FOT on patients with respiratory failure and obstructive sleep apnea (OSA). By using a nasal mask instead of a mouthpiece, the influences of the nasal passage and upper shunt alter the measured mechanical impedance. In this paper, we investigated the effects of the nasal passage and mask on FOT measurements from eight healthy subjects. A method for flow correction has been developed, which contains a pressure-flow characteristics compensation of the undetermined flow leakage at the face-mask interface. Impedance calculation and parameter estimation were performed in the frequency domain using fast Fourier transform (FFT). Average nasal parameters were Rnaw=4.07 cmH2O/l/s for resistance and Lnaw=0.0183 cmH2O/l/s2 for inertance. On average, the nasal resistance corresponds to 65.85% of the total resistance.

Distant metastasis detected by routine staging in breast cancer patients participating in the national German screening programme: consequences for clinical practice.

PURPOSE: To determine frequency of routine radiological staging of breast cancer patients diagnosed in a German Breast Cancer Screening Center from 2007 to 2014, the incidence and consequences of distant metastases detected and the resulting implications for clinical routine. METHODS: Records of 896 patients with primary breast cancer diagnosed in the Screening Centre and treated in five participating hospitals were analyzed retrospectively. Evaluation included frequency and type of staging procedures and results with respect to distant metastasis and their consequences on clinical management. RESULTS: 894/896 Patients (99.8 %) received staging for distant metastases by bone scintigraphy, chest X-ray and liver sonography and/or CT/MRT diagnostics. Distant metastasis was suggested In 6/894 patients but excluded in 3 by further diagnostics or clinical course. Thus, 3 (0.3 %) were clinically verified to have metastatic disease in bone (n = 2; both pT2) or in bone and lung (n = 1; cT4, cN3). CONCLUSION: Due to the low incidence of verified metastatic disease, the high false positive rate of staging procedures and the unfavorable cost/benefit ratio routine radiological staging should be completely omitted in asymptomatic breast cancer patients diagnosed in a breast cancer screening programme.