reader's response to the webcast video editorial entitled "the international code of medical ethics of the World Medical Association".
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Codes of Ethics↗
Biomedical subjects
Stephen S Lefrak
Publications and source records attributed to Stephen S Lefrak.
3He diffusion MRI of the lung.
RATIONALE AND OBJECTIVES: MR imaging of the restricted diffusion of laser-polarized 3He gas provides unique insights into the changes in lung microstructure in emphysema. RESULTS: We discuss measurements of ventilation (spin density), mean diffusivity, and the anisotropy of diffusion, which yields the mean acinar airway radius. In addition, the use of spatially modulated longitudinal magnetization allows diffusion to be measured over longer distances and times, with sensitivity to collateral ventilation paths. Early results are also presented for spin density and diffusivity maps made with a perfluorinated inert gas, C3F8. METHODS: Techniques for purging and imaging excised lungs are discussed.
Diffusion Magnetic Resonance Imaging↗
Results of lung volume reduction surgery in patients meeting a national emphysema treatment trial high-risk criterion.
OBJECTIVES: A report from the National Emphysema Treatment Trial indicated that lung volume reduction candidates with a forced expiratory volume in 1 second and a diffusing capacity of carbon monoxide of 20% or less of predicted value were at high risk for mortality and were unlikely to benefit from surgical intervention. This article examines the applicability of the National Emphysema Treatment Trial findings to our own patients. METHODS: We reviewed 280 patients who underwent bilateral lung volume reduction surgery at our institution between January 1993 and December 2001. All patients met our selection criteria, including heterogeneous distribution of emphysema. Of these 280 patients, 20 patients had both a preoperative forced expiratory volume in 1 second and a diffusing capacity of carbon monoxide of less than or equal to 20% of the predicted normal values, thus meeting one National Emphysema Treatment Trial criterion for high risk. Outcomes of the 20 patients were assessed through 5 years after the operation. The survival of the 20 patient cohort was compared with that of the 260 patients not meeting the National Emphysema Treatment Trial high-risk criterion. RESULTS: Ninety-day operative mortality included 1 (5%) patient. In all patients the forced expiratory volume in 1 second increased from 0.46 L (17%) to 0.78 L (32%), a 73% change; the diffusing capacity of carbon monoxide increased from 16% to 27%, a 70% improvement; residual volume decreased from 6.33 L (305%) to 4.26 L (205%), a 33% improvement; and room air arterial partial pressure of oxygen increased from 55 mm Hg to 64 mm Hg. Kaplan-Meier 5-year survivals did not differ between the high-risk and non-high-risk groups. CONCLUSIONS: Patients with a forced expiratory volume in 1 second and a diffusing capacity of carbon monoxide of 20% or less of predicted value might experience improvements in lung function, exercise tolerance, and quality of life with acceptable morbidity and mortality after lung volume reduction surgery.
Aged↗
Long-term outcome of bilateral lung volume reduction in 250 consecutive patients with emphysema.
OBJECTIVE: Numerous reports have confirmed the early benefits of lung volume reduction surgery for selected patients with emphysema. This report documents the long-term survival and functional results after lung volume reduction surgery. METHODS: Between January 1993 and June 2000, a total of 250 consecutive patients underwent bilateral lung volume reduction surgery through median sternotomy at our institution. All patients had disabling dyspnea, thoracic hyperinflation, and a heterogeneous pattern of emphysema with suitable target areas for resection. Preoperative pulmonary rehabilitation was required and post-rehabilitation data were used as the baseline for data analysis. Follow-up ranged from 1.8 to 9.1 years (median 4.4 years). RESULTS: Prolonged air leaks (>7 days) were the most common complication (45.2%, n = 113). Reexploration rates for air leak and bleeding were 3.2% (n = 8) and 1.2% (n = 3), respectively. Eighteen patients (7.2%) required reintubation and mechanical ventilation. The in-hospital mortality in this series was 4.8% (n = 12). The median length of hospitalization was 9 days (range 4-168 days). Kaplan-Meier survivals after lung volume reduction surgery were 93.6%, 84.4%, and 67.7% at 1, 3, and 5 years, respectively. Eighteen patients (7.2%) have subsequently undergone lung transplantation after a median interval of 4.3 years (range 2.1-6.4 years). Spirometric values, lung volumes, and gas exchange parameters improved after surgery. The forced expiratory volume in 1 second and the residual volume showed statistically significant improvements between preoperative values and each time point of follow-up. Health-related quality of life showed significant postoperative improvement and with time correlated well with the improvement in forced expiratory volume in 1 second. CONCLUSIONS: Lung volume reduction surgery produces significant functional improvement for selected patients with emphysema. For most of these patients, benefits appear to last at least 5 years.
Aged↗
A prospective evaluation of lung volume reduction surgery in 200 consecutive patients.
OBJECTIVES: Though numerous studies have demonstrated the short-term efficacy of lung volume reduction surgery (LVRS) in select patients with emphysema, the longer-term follow-up studies are just being reported. The primary objectives of this study were to assess long-term health-related quality of life, satisfaction, physiologic status, and survival of patients following LVRS. DESIGN: We used a prospective cohort study design to assess the first 200 patients undergoing bilateral LVRS (from 1993 to 1998), with follow-up through the year 2000. Each patient served as his own control, initially receiving optimal medical management including exercise rehabilitation before undergoing surgery. Preoperative postrehabilitation data were used as the baseline for comparisons with postoperative data. The primary end points were the effects of LVRS on dyspnea (modified Medical Research Council dyspnea sale), general health-related quality of life (Medical Outcomes Study 36-Item Short-Form Health Survey [SF-36]), patient satisfaction, and survival. The secondary end points were the effects of LVRS on pulmonary function, exercise capacity, and supplemental oxygen requirements. SETTING: A tertiary care urban university-based referral center. PATIENTS: Eligibility requirements for LVRS included disabling dyspnea due to marked airflow obstruction, thoracic hyperinflation, and heterogeneously distributed emphysema that provided target areas for resection. Patients were assessed at 6 months, 3 years, and 5 years after surgery. INTERVENTIONS: Preoperative pulmonary rehabilitation and bilateral stapling LVRS. MEASUREMENTS AND RESULTS: The 200 patients accrued 735 person-years (mean +/- SD, 3.7 +/- 1.6 years; median, 4.0 years) of follow-up. Over the three follow-up periods, an average of > 90% of evaluable patients completed testing. Six months, 3 years, and 5 years after surgery, dyspnea scores were improved in 81%, 52%, and 40% of patients, respectively. Dyspnea scores were the same or improved in 96% (6 months), 82% (3 years), and 74% (5 years) of patients. Improvements in SF-36 physical functioning were demonstrated in 93% (6 months), 78% (3 years), and 69% (5 years) of patients. Good-to-excellent satisfaction with the outcomes was reported by 96% (6 months), 89% (3 years), and 77% (5 years) of patients. The FEV(1) was improved in 92% (6 months), 72% (3 years), and 58% (5 years) of patients. Changes in dyspnea and general health-related quality-of-life scores, and patient satisfaction scores were all significantly correlated with changes in FEV(1). Following surgery, the median length of hospital stay in survivors was 9 days. The 90-day postoperative mortality was 4.5%. Annual Kaplan-Meier survival through 5 years after surgery was 93%, 88%, 83%, 74%, and 63%, respectively. During follow-up, 15 patients underwent subsequent lung transplantation. CONCLUSIONS: In stringently selected patients, LVRS resulted in substantial beneficial effects over and above those achieved with optimized medical therapy. The duration of improvement was at least 5 years in the majority of survivors.
Dyspnea↗
Surgery for emphysema.
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Contraindications↗
Quantitative in vivo assessment of lung microstructure at the alveolar level with hyperpolarized 3He diffusion MRI.
The study of lung emphysema dates back to the beginning of the 17th century. Nevertheless, a number of important questions remain unanswered because a quantitative localized characterization of emphysema requires knowledge of lung structure at the alveolar level in the intact living lung. This information is not available from traditional imaging modalities and pulmonary function tests. Herein, we report the first in vivo measurements of lung geometrical parameters at the alveolar level obtained with 3He diffusion MRI in healthy human subjects and patients with severe emphysema. We also provide the first experimental data demonstrating that 3He gas diffusivity in the acinus of human lung is highly anisotropic. A theory of anisotropic diffusion is presented. Our results clearly demonstrate substantial differences between healthy and emphysematous lung at the acinar level and may provide new insights into emphysema progression. The technique offers promise as a clinical tool for early diagnosis of emphysema.
Diffusion↗
Integrating social and ethics-based aspects of medicine into physician education.
Ethics plays an important, formative role in medical education, stimulating the transformation of a physiologist-scientist into a compassionate and competent clinician. Our clinical ethics program challenges students to observe and recognize inherent value conflicts and understand how such issues must be resolved in their day-to-day work. Advances in biomedical research that hold potential to enhance human health and treat disease are provoking controversial questions of current practices in medical ethics and spawning new, unprecedented ethical dilemmas.
Biomedical Research↗