PT - JOURNAL ARTICLE AU - Y Ying AU - R Peslin AU - C Duvivier AU - C Gallina AU - J Felicio da Silva TI - Respiratory input and transfer mechanical impedances in patients with chronic obstructive pulmonary disease AID - 10.1183/09031936.93.03101186 DP - 1990 Nov 01 TA - European Respiratory Journal PG - 1186--1192 VI - 3 IP - 10 4099 - http://erj.ersjournals.com/content/3/10/1186.short 4100 - http://erj.ersjournals.com/content/3/10/1186.full SO - Eur Respir J1990 Nov 01; 3 AB - Total respiratory input (Zin) and transfer (Ztr) mechanical impedances were measured from 4-30 Hz in 9 patients with severe chronic obstructive pulmonary disease (COPD) and in 12 healthy subjects. Zin was obtained by applying a pressure input around the head to minimize transmural pressure across extrathoracic airway walls, and Ztr was obtained with a pressure input at the chest. In agreement with previous studies total respiratory compliance and inertance were decreased in patients, while effective input resistance was increased and exhibited a negative frequency dependence. Effective transfer resistance (Re(Ztr)) was also increased at all frequencies, and, in some patients, the Re(Ztr)-frequency curve was sigmoid in shape, which was never seen in normals. When Ztr was analysed with a six-coefficient monoalveolar model featuring tissue properties, alveolar gas compliance, and airways properties, the model fitted the data less closely in patients than in normals and, in the former, provided unrealistic coefficients. Such was also the case with a bialveolar model. A better fit with more realistic values for the coefficients was obtained in selected patients with a model where central and peripheral (Rp) airway resistance were separated by a shunt representing airway wall compliance (Cb): Cb was found to range from 0.029-0.062 l.kPa-1 and Rp represented 44-81% of total airway resistance.