Chest
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Comparative Study
Comparison of exercise cardiac output by the Fick principle using oxygen and carbon dioxide.
Theoretically, cardiac output (CO) calculated by the Fick principle should be the same using O(2) (CO[O2]) or CO2 (CO[CO2]) as the test gas. However, agreement depends on the accuracy of gas exchange and blood gas measurements and the validity of the equations to convert measured variables into blood gas contents. Considering the widespread use of indirect estimates of pulmonary artery blood PCO2 and CO2 content to measure Fick principle CO during exercise, we wished to determine whether CO[O2] and CO[CO2] were equal during exercise and whether CO[CO2] could be accurately and precisely determined using direct measures of pulmonary artery blood. PREPARATION AND METHODS: Five healthy young nonsmoking volunteer men performed incremental exercise from rest to peak exercise on two separate occasions with intervening rest. Catheters were placed in brachial and pulmonary arteries to allow repeated blood sampling every minute during concurrent breath-by-breath gas exchange measurements from rest to peak exercise. CO[O2] was compared with CO[CO2] at multiple levels of exercise. Using standard equations, arterial and mixed venous O2 contents were calculated from hemoglobin concentration (Hb), oxyhemoglobin saturation (SO2), and PO2, whereas CO2 contents were calculated from PCO2, pH, Hb, and SO2. Blood gas analyzers were used for measurement of pH, PCO2, and PO2, and a co-oximeter was used for measurement of Hb and SO2. Initial calculations suggested that exercise CO[CO2] was 14% higher than CO[O2] and helped disclose small systematic measurement errors in PCO(2) for values > 45 mm Hg detected by proficiency testing surveys and documented with blood tonometry in the blood gas analyzer. ⋯ The increased variability of Fick principle CO[CO2] compared with CO[O2] is attributable to the much lower extraction ratio for CO2 and the greater complexity in calculation of blood CO2 than O2 contents. These results raise concerns about the accuracy and precision of estimating CO and stroke volume using CO2 as a test gas, even with direct measurement of blood CO2 contents in normal subjects.
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Comparative Study
Bronchoscopy training: current fellows' experiences and some concerns for the future.
To determine current pulmonary fellows' perspectives about their bronchoscopy training. ⋯ Approaches to bronchoscopy instruction and the components of bronchoscopy experiences vary considerably among institutions and are associated with pulmonary fellows' perceptions of bronchoscopy proficiency and training program quality. Definition of an optimum bronchoscopy curriculum remains necessary.
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Letter Comparative Study
Transudative pleural effusions: false reassurance against malignancy.
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We sought to investigate the effect of lung volume reduction surgery (LVRS) on regional lung ventilation. ⋯ Small airways ventilation in lung regions that had and had not been operated on is associated with a greater improvement in lung mechanics following LVRS.
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Thyroid storm is a rare disorder characterized by hypertension, hyperthermia, and multiple systems involvement. Early recognition and treatment of thyroid storm are essential in reducing morbidity and mortality from this disorder. We present the case of a patient with an atypical (normothermic, normotensive) presentation of thyroid storm, accompanied by multiple organ dysfunction syndrome, including lactic acidosis and liver dysfunction, both of which are very rare complications. This case highlights both the multiple organ systems that can be involved in thyroid storm and the importance of recognizing atypical presentations of thyroid storm.