Gas flow during bronchoscopic ablation therapy causes gas emboli to the heart: a comparative animal study.

BACKGROUND: Thermal ablation is one of the most commonly used modalities to treat central airway obstruction. Both laser and argon plasma coagulation (APC) have been reported to cause gas emboli and cardiac arrest. We sought to determine whether bronchoscopic ablation therapy can result in systemic gas emboli, correlate their presence with the rate of gas flow, and establish whether a zero-flow (ZF) modality would result in the significant reduction or elimination of emboli. METHODS: CO(2) laser delivered through a photonic bandgap fiber (PBF) and APC were applied in the trachea and mainstem bronchi of six anesthetized sheep at varying dosages and gas flow rates. Direct epicardial echocardiography was used to obtain a four-chamber view and detect gas emboli. RESULTS: The presence of gas flow accompanying APC and the CO(2) laser with forward flow correlated significantly with the appearance of gas bubbles in the atria. A definite dose response was observed between the gas flow rate and the number of bubbles seen. When the CO(2) laser was delivered through a PBF with ZF to the trachea or bronchi, no bubbles were observed. CONCLUSION: Bronchoscopic thermal ablation therapy using gas flow is associated with gas emboli in a dose-dependent fashion. The use of the flexible PBF with ZF is not associated with the development of gas emboli. Further study is required to determine whether a clinically safe threshold of gas emboli exists, and the relationships among the pathologic depth of tissue destruction, gas flow, pulse duration, and the development of gas emboli.

Four-gene expression ratio test for survival in patients undergoing surgery for mesothelioma.

BACKGROUND: Malignant pleural mesothelioma has few effective treatments, one being cytoreductive surgery. We previously developed a gene ratio test to predict outcome of malignant pleural mesothelioma patients undergoing surgery. In this study, we investigated the predictive value and technical assay performance of this test in patients with malignant pleural mesothelioma. METHODS: Clinical data were obtained prospectively from 120 consecutive patients with malignant pleural mesothelioma who were scheduled for debulking surgery at one institution. Specimens were obtained at surgery or by pleural biopsy examination. Expression data for four genes were collected from tumor specimens, and three ratios of gene expression (TM4SF1/PKM2, TM4SF1/ARHGDIA, and COBLL1/ARHGDIA) were determined by quantitative reverse transcriptase-polymerase chain reaction. Patients were assigned to good or poor outcome groups by the gene ratio test. Survival was estimated by the Kaplan-Meier method and the log-rank test in univariate analyses. A multivariable Cox proportional hazards model was used to control for prognostic factors. Technical robustness was determined by using up to 30 specimens per patient, two biopsy techniques, and two performance sites. All statistical tests were two-sided. RESULTS: The test predicted overall survival (P < .001) and cancer-specific survival (P = .007) in univariate analysis and overall survival in multivariable analysis (hazard ratio for death = 2.09, 95% confidence interval [CI] = 1.27 to 3.45, P = .004). The test was reproducible within patients and repeatable between two determinations for specimens with widely varying tumor cell contents. Repeatability between two determinations was 88.5% (95% CI = 84.0% to 92.2%) or, when technically unacceptable test values were excluded, 91.9% (95% CI = 87.4% to 95.1%). Reproducibility between two determinations was 96.1% (95% CI = 86.5% to 99.5%). Combining the gene ratio test and other prognostic factors allowed prospective discrimination between patients at high risk (median survival = 6.9 months, 95% CI = 2.6 to 8.9 months; 3-year survival = 0%) and low risk (median survival = 31.9 months, 95% CI = 21.9 to 41.7 months; 3-year survival = 42%). CONCLUSION: The gene ratio test for survival of patients with malignant pleural mesothelioma has robust predictive value and technical assay performance.