Pulmonary Vascular Resistance in Emphysema: Protocol

We examined lung function and resting pulmonary hemodynamics in 12 patients with type A COPD. The study protocol, approved by the Institutional Review Board of the Columbia Presbyterian Medical Center, was explained in detail and written, informed consent was secured for all procedures. On the first day, patients underwent complete pulmonary function testing. Immediately after completion of pulmonary function testing, subjects were familiarized with the catheterization laboratory and the respiratory equipment. On the following day, right heart catheterization was performed with the patients in a supine position, unsedated and in the postabsorptive basal state. Buy inhalers online other A flow-directed balloon catheter was passed to the pulmonary artery under fluoroscopic guidance for measurement of pulmonary arterial pressures, pulmonary arterial wedge pressure, and sampling mixed venous blood. A No. 6 F Coumand catheter was passed to the right atrium for injection of indocyanine green for measurement of cardiac output. A brachial artery was cannulated to record systemic arterial pressure and to sample systemic arterial blood.
Hemodynamic measurements were obtained over a 30-min period. Pulmonary arterial wedge, pulmonary arterial, and systemic arterial blood pressures were recorded every 5 min. Pressures represent average values recorded over three respiratory cycles. The ECG was monitored continuously. Cardiac output, minute ventilation, arterial and mixed venous blood gases, and pH were measured between the 12th and 16th minute. All patients breathed room air.
Technical Procedures
Spirometry was performed on a Collins model 2303 Maximodular Lung Analyzer (Warren E. Collins Inc, Braintree, Mass) equipped with a 10-L water-sealed spirometer. Lung volumes were measured by closed circuit rebreathing of helium until (1)5 min had elapsed and less than a 0.05 percent change in helium concentration was observed over the previous 30 s or (2) 7 min had elapsed. The single-breath carbon monoxide diffusing capacity (DcoSB) was measured by the single breath method using a standard 10 s of breath holding. The washout volume was 650 ml (350 ml if the vital capacity was less than 1.6 L) and the collection volume was 700 ml. The DcoSB (STPD) was calculated as follows: DcoSB=VA(60/time) (l/PB-47)ln(CO.Hee/COeHe.), where PB is barometric pressure, CO, and COp are inspired and expired carbon monoxide concentrations, respectively, and He, and Hee are inspired and expired helium concentrations, respectively. Alveolar volume (Va) was determined by the sum of the inspiratory vital capacity which is measured during the test, and the residual volume (RV), which is measured separately during the closed circuit helium rebreathing lung volume measurement.
Predicted values for FEV, and FVC are those of Morris and coworkers. Predicted values for RV and functional residual capacity (FRC) are those of Goldman and Becklake. Predicted total lung capacity (TLC) was calculated as the sum of the predicted RV and predicted FVC. Predicted values for Dcocn were those of Gaensler and Wright.

This entry was posted in Emphysema and tagged airflow obstruction, emphysema, pulmonary function, pulmonary vascular resistance, resistance pulmonary blood.