Small Airway Dysfunction and Abnormal Exercise Responses. A Study in Coal Miners.

RATIONALE: Coal mine dust exposure can cause symptoms and loss of lung function from multiple mechanisms, but the roles of each disease process are not fully understood. OBJECTIVES: We investigated the implications of small airway dysfunction for exercise physiology among a group of workers exposed to coal mine dust. METHODS: Twenty coal miners performed spirometry, first breathing air and then helium-oxygen, single-breath diffusing capacity, and computerized chest tomography, and then completed cardiopulmonary exercise testing. MEASUREMENTS AND MAIN RESULTS: Six participants meeting criteria for small airway dysfunction were compared with 14 coal miners who did not. At submaximal workload, miners with small airway dysfunction used a higher proportion of their maximum voluntary ventilation and had higher ventilatory equivalents for both O2 and CO2. Regression modeling indicated that inefficient ventilation was significantly related to small airway dysfunction but not to FEV1 or diffusing capacity. At the end of exercise, miners with small airway dysfunction had 27% lower O2 consumption. CONCLUSIONS: Small airway abnormalities may be associated with important inefficiency of exercise ventilation. In dust-exposed individuals with only mild abnormalities on resting lung function tests or chest radiographs, cardiopulmonary exercise testing may be important in defining causes of exercise intolerance.

Risk stratification in acute pulmonary embolism: frequency and impact on treatment decisions and outcomes.

OBJECTIVES: Guidelines have recommended that risk stratification be performed in patients diagnosed with an acute pulmonary embolism (PE). No study has described the use of risk stratification in routine clinical practice. The purpose of this study was to measure the frequency and impact of risk stratification on treatment decisions and outcomes in patients admitted with acute PE. METHODS: A retrospective cohort study was conducted of all of the patients admitted with acute PE at two Geisinger community-based teaching hospitals between 2006 and 2011. Baseline demographics, vital signs, and relevant clinical variables were recorded. The Pulmonary Embolism Severity Index was calculated for each patient. Risk stratification was defined as the measurement of either a biomarker or an echocardiogram within 24 hours of admission. The outcomes measured were short-term adverse events (in-hospital mortality or need for intensive care) and 30-day mortality. RESULTS: The mean age for the study cohort (n = 889) was 61 ± 17 years and 52% were men. Overall, 59% of study subjects were risk stratified. The frequency of risk stratification did not change over time. Risk stratification was associated with assignment to a higher acuity of care and increased use of thrombolysis and inferior vena cava filter placement. When controlling for severity of illness, risk stratification was a significant predictor of worsened short-term adverse outcome (odds ratio 3.43, 95% confidence interval 1.75-6.74, P < 0.001) but was not associated with improved 30-day mortality (odds ratio 1.14, 95% confidence interval 0.66-1.95, P = 0.64). CONCLUSIONS: Risk stratification is frequently performed in patients admitted with acute PE and has had a stable prevalence during a 5-year period. The use of risk stratification in acute PE is associated with assignment to higher levels of care and with more advanced treatments. Despite more intense treatment, risk stratification does not improve either short-term outcomes or 30-day mortality.