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We measured the uptake of the soluble inert gas dimethyl ether (DME) from a segment of the conducting airways to estimate mucosal blood flow (Qaw) noninvasively. The subjects inhaled, from the functional residual capacity position, a 300-ml gas mixture containing 35% DME, 8% helium, 35% oxygen, and the balance nitrogen; they held their breath for 5 s and then exhaled into a spirometer. During exhalation, the instantaneous concentrations of DME and helium were recorded together with expired gas volume. The maneuver was repeated with breathhold times of 5, 10, 15, and 20 s. We calculated Qaw using the time-dependent decrease in DME concentration in relation to the helium concentration in an expired volume fraction between 80 and 130 ml (representing an anatomic dead-space segment distal to the glottis) and the mean DME concentration. In 10 healthy nonsmokers, mean (+/- SE) Qaw was 8.0 +/- 1.3 ml/min, or 8 +/- 2 microliters/min/cm2 mucosal surface. We obtained a value of 12 +/- 3 microliters/min/cm2 in a validation experiment in sheep. Inhaled methoxamine (nebulized dose 10 mg) caused a 65 +/- 19% decrease (p0.05), and albuterol (nebulized dose 2.5 mg) a 92 +/- 17% increase (p0.05), in mean Qaw in seven subjects, with the maximum changes occurring immediately or 15 min postinhalation. We conclude that the DME uptake method is an acceptable noninvasive means of estimating airway mucosal blood flow in humans and its modification by vasoactive substances.

Background: Despite being commercially available for a few years now, the literature regarding the outcome of UltraflexTM stent insertion in complex malignant airway stenoses is sparse. Objectives: To assess long-term complications and survival in patients with complex malignant airway stenoses treated with insertion of nitinol stents. Methods: 60 consecutive patients with UltraflexTM stent insertion for malignant airway stenoses were included. Follow-up was obtained in all patients. Results: 62 UltraflexTM stents (covered = 51, uncovered = 11) were implanted in 60 patients. Diagnoses were bronchial carcinoma (n = 50), esophageal carcinoma (n = 3) and metastases (n = 7). Stents were inserted in the trachea (n = 5), main bronchi/intermediate bronchus (n = 22), from main bronchi/intermediate bronchus to lobar bronchi (n = 28) or in the lobar bronchi themselves (n = 7). Successful reopening of the stenoses and relief were achieved in all patients. There was no procedure-related mortality. Complications included mucous plugging in 8%, stenosing granulation tissue in 5%, tumor ingrowth in 5% and stent migration in 5% of patients. Using Kaplan-Meier estimates, the overall mean survival was 160 days (standard error: 30). Median survival was 91 days. The overall 3- and 6-month survival were 52 and 20%, respectively. Death (n = 59, 98%) was attributed mainly to disease progression with cachexia and metastases, pneumonia (n = 5, 10%), and hemoptysis (n = 1, 2%). Conclusion: UltraflexTM stents have a low complication rate and can be effectively used in complex malignant airway stenoseswith marked asymmetry or irregularity, angulation or changing diameters.

A retrospective 5 year follow-up study was performed in 140 patients with unequivocal ischemia during exercise radionuclide angiography (greater than or equal to 10% decrease in left ventricular ejection fraction or greater than or equal to 5% decrease in ejection fraction together with a distinct regional wall motion abnormality). In 84 patients (60%), ischemia during radionuclide angiography was silent (silent ischemia group), whereas 56 patients experienced angina during the test (symptomatic group). Work load and antianginal medication were similar in both groups. Critical cardiac events (unstable angina, myocardial infarction, cardiac death) occurred in 27% of patients in the silent ischemia group and 16% of those in the symptomatic group (p = NS); however, myocardial infarction or death was more frequent in patients with silent ischemia (22% versus 9%; p less than 0.05). If there was additional exercise-induced ST segment depression, the rate of critical events was further increased (p less than 0.05). The difference in critical cardiac events seemed to be influenced by the higher incidence of revascularization procedures in symptomatic patients, whereas medical therapy had no similar effect. Thus, these findings suggest that patients with documented severe ischemia should undergo left heart catheterization and revascularization irrespective of symptoms to improve their prognosis.