Pulmonary Vascular Resistance in Emphysema: Data Analysis

Pulmonary Vascular Resistance in Emphysema: Data AnalysisPredicted 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.
Vascular pressures were measured relative to the level of the midright atrium as the average values over three respiratory cycles. Pulmonary arterial pressures were measured with a strain gauge (Statham P23Db). Systemic arterial pressures were recorded with a second gauge (Statham). Canadian health care mall All pressures were recorded on a recorder (Electronics for Medicine DR-8).
Cardiac output was measured by an indicator-dilution method using indocyanine green dye. Approximately 1.25 mg of green dye in 0.5 ml of saline solution was preloaded into the distal lumen of the right atrial catheter by means of two semiautomatic calibrated syringes. Serum albumin was added to the dye solution in an amount of 0.1 g/mg of dye. The injectate was delivered by flushing the lumen with 5 ml of saline solution. No attempt was made to synchronize the injections with any event of the cardiac cycle so that the timing of the manual injection was completely random. Blood was sampled from the brachial artery at 2.5 ml/s through a densitometer (Gilford model 103IR) and displayed and photographed on the recorder (DR 8). Dye curves were calibrated individually for each patient.
Resistance to pulmonary blood flow was assessed from the difference between the pulmonary arterial diastolic and mean wedge pressures and expressed as the pulmonary diastolic gradient (PDG). The pulmonary diastolic pressure gradient reflects the degree of resistance to pulmonary blood flow independent of changes in the level of the left heart pressure or cardiac output. The normal pulmonary diastolic gradient is < 3 mm Hg.
Ventilation and respiratory frequency were recorded on a gasometer (Tissot). Arterial and mixed venous blood samples were analyzed for oxygen and carbon dioxide tension and pH with a microanalyzer (Radiometer model BMS 3Mk2, Radiometer, Copenhagen).
The relationship between pulmonary function and hemodynamic observations in patients with emphysema was compared with our previous report of findings in 33 patients with chronic, diffuse ILD. In a fashion similar to the current study, those patients were selected to obtain a broad spectrum of disease, ranging from the asymptomatic to those with marked respiratory compromise. Individuals with evidence of airways obstruction, intercurrent infection, obesity, and respiratory muscle weakness were excluded. Of the 33 patients, 16 had progressive systemic sclerosis, 11 had sarcoidosis, and 6 had ILD of various causes (3 idiopathic pulmonary fibrosis, 2 systemic lupus, 1 bagassosis). The catheterization protocol was similar to the emphysema protocol.

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