Total lung capacity by plethysmography and high-resolution computed tomography in COPD.

AIM: To characterize and compare total lung capacity (TLC) measured by plethysmography with high-resolution computed tomography (HRCT), and to identify variables that predict the difference between the two modalities. METHODS: Fifty-nine consecutive patients referred for the evaluation of COPD were retrospectively reviewed. Patients underwent full pulmonary function testing and HRCT within 3 months. TLC was obtained by plethysmography as per American Thoracic Society/European Respiratory Society standards and by HRCT using custom software on 0.75 and 5 mm thick contiguous slices performed at full inspiration (TLC). RESULTS: TLC measured by plethysmography correlated with TLC measured by inspiratory HRCT (r = 0.92, P < 0.01). TLC measured by plethysmography was larger than that determined by inspiratory HRCT in most patients (mean of 6.46 ± 1.28 L and 5.34 ± 1.20 L respectively, P < 0.05). TLC measured by both plethysmography and HRCT correlated significantly with indices of airflow obstruction (forced expiratory volume in 1 second/forced vital capacity [FVC] and FVC%), static lung volumes (residual volume, percent predicted [RV%], total lung capacity, percent predicted [TLC%], functional residual capacity, percent predicted [FRC%], and inspiratory capacity, percent predicted), and percent emphysema. TLC by plethysmography and HRCT both demonstrated significant inverse correlations with diffusion impairment. The absolute difference between TLC measured by plethysmography and HRCT increased as RV%, TLC%, and FRC% increased. Gas trapping (RV% and FRC%) independently predicted the difference in TLC between plethysmography and HRCT. CONCLUSION: In COPD, TLC by plethysmography can be up to 2 L greater than inspiratory HRCT. Gas trapping independently predicts patients for whom TLC by plethysmography differs significantly from HRCT.

The effect of chronic sputum production on respiratory symptoms in severe COPD.

BACKGROUND: Chronic sputum production is a significant but variable complaint in COPD; its effect on symptom burden has not been comprehensively described. We sought to characterize the daily burden of chronic sputum production in severe COPD and the phenotype of those with chronic sputum symptoms. METHODS: We studied 50 outpatients with severe COPD who used an electronic diary to document peak expiratory flow (PEF) and respiratory symptoms daily for up to 2 years. A sputum index was derived based on complaints of sputum quantity, color, and consistency, and patients were divided into groups based on average daily sputum index (Low, Medium, High). The presence and severity of respiratory symptoms were scored by a novel method using daily changes in symptoms and PEF from baseline and were categorized into mild, moderate, and severe. Percent emphysema was measured using quantitative CT. RESULTS: In the 14,500 observation days, severe symptom days were greater in the Medium and High groups (379/6089, 1609/4091, and 2624/4317 observation days in Low, Medium, and High, p < 0.0001). The same trend was found even when sputum complaints were removed from the symptom severity score. Observed/predicted PEF ratio was lower in the High group (0.56 ± 0.24, 0.55 ± 0.19, and 0.42 ± 0.12 in each group, p < 0.05 for High compared to Medium and Low). Percent emphysema inversely correlated with average sputum index and quantity (r = -0.449 and r = -0.584, respectively, p < 0.05). CONCLUSIONS: Increased sputum production in severe COPD is frequently encountered daily and is associated with more respiratory symptoms, worse airflow obstruction, and less emphysema.

Diagnostic pathways and delays on route to operative intervention in acute appendicitis.

The purpose of this study was to determine the elements associated with delay in the evaluation of acute appendicitis at a community teaching hospital. We performed a retrospective chart review of patients undergoing operative exploration for presumed appendicitis in a 12-month period. Cases were categorized by the presence or absence of advanced radiographic imaging. Demographic information and time intervals from triage to operative incision were compared. One hundred twenty-four patients underwent operative exploration for presumed appendicitis. Forty-one patients had no advanced imaging, 67 had a CT scan, 8 had a sonogram, and 8 had both CT/sonogram. Patients using advanced radiographic imaging prior to operative exploration were no less likely to have a normal appendix at surgery. Diagnostic imaging significantly increased the preoperative emergency department length of stay. Two-thirds of patients with presumed acute appendicitis were imaged before operative exploration. The use of abdominal CT and sonogram resulted in significantly increased preoperative emergency department length of stay with no apparent improvement in diagnostic accuracy.