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Biomedical subjects

R D Yusen

Publications and source records attributed to R D Yusen.

At least 19 recordsLinked to original sources
PubMed2001

Subcutaneous enoxaparin once or twice daily compared with intravenous unfractionated heparin for treatment of venous thromboembolic disease.

BACKGROUND: Low-molecular-weight heparins administered subcutaneously once or twice daily have been reported to be as safe and efficacious as intravenous unfractionated heparin in the treatment of acute venous thromboembolic disease. OBJECTIVE: To determine whether subcutaneous enoxaparin administered once or twice daily is as effective as continuously infused unfractionated heparin in acute symptomatic venous thromboembolic disease. DESIGN: Randomized, controlled, partially blinded equivalence trial. SETTING: 74 hospitals in 16 countries. PATIENTS: 900 patients with symptomatic lower-extremity deep venous thrombosis, including 287 (32%) with confirmed pulmonary embolism. INTERVENTIONS: Initial therapy with dose-adjusted intravenous unfractionated heparin compared with subcutaneous enoxaparin at fixed dosages of 1.0 mg/kg of body weight twice daily or 1.5 mg/kg once daily. Long-term oral anticoagulation was started in all patients within 72 hours of randomization. MEASUREMENTS: Clinical end points assessed during a 3-month follow-up period. RESULTS: Equivalent efficacy was seen in the heparin group and both enoxaparin groups. Symptomatic venous thromboembolism recurred in 12 of 290 patients receiving unfractionated heparin (4.1%), 13 of 298 patients receiving once-daily enoxaparin (4.4%), and 9 of 312 patients receiving twice-daily enoxaparin (2.9%). Compared with unfractionated heparin, the treatment difference was 0.2% (95% CI, -3.04% to 3.49%) for once-daily enoxaparin and -1.2% (CI, -4.2% to 1.7%) for twice-daily enoxaparin. Incidence of major hemorrhage did not differ among the three treatment groups. Major hemorrhage occurred in 6 of 290 patients (2.1%) in the unfractionated heparin group, 5 of 298 patients (1.7%) in the once-daily enoxaparin group, and 4 of 312 patients (1.3%) in the twice-daily enoxaparin group. CONCLUSIONS: Subcutaneous enoxaparin once or twice daily is as effective and safe as dose-adjusted, continuously infused unfractionated heparin in the prevention of recurrent symptomatic venous thromboembolic disease.

Administration, Cutaneous↗
PubMed2001

Lymphoproliferative disease after lung transplantation: comparison of presentation and outcome of early and late cases.

BACKGROUND: Post-transplantation lymphoproliferative disease (PTLD) after lung transplantation has not been fully characterized. In previous studies, the incidence has varied substantially, and most cases have been reported during the first year after transplantation. The purpose of this study was to review our center's experience with PTLD and to analyze the pattern of disease and determinants of outcome. METHODS: Among 494 adult lung (n = 491) or heart-lung (n = 3) recipients, 30 cases of PTLD were retrospectively identified. The cases were classified by site(s) of involvement, histology and time of onset (early, < or =1 year, and late, >1 year after transplantation). The outcome of each case was ascertained, and risk factors for death were analyzed in a multivariate model. RESULTS: PTLD was identified in 30 (6.1%) of the recipients during 1,687 patient-years (median 2.8 years) of follow-up. The incidence density was 1.8 cases per 100 patient-years. Fourteen cases were diagnosed during the first year after transplantation, and 16 cases in subsequent years. The incidence density was significantly higher in the first year than in later years (3.3 cases/100 patient-years versus 1.3 cases/100 patient years; p <.008). Presentation in the thorax and involvement of the allograft were significantly more common in the early cases (thorax: 12 of 14, 86%; allograft: 9 of 14, 64%) than in the late cases (thorax: 2 of 16, 12%; allograft: 2 of 16, 12%). There was no difference in survival after the diagnosis of PTLD between the early and late cases, but survival time after diagnosis was significantly longer in cases with, than those without, allograft involvement (median 2.6 years vs 0.2 year, respectively; log rank p = 0.007). The presentation and pattern of organ involvement of PTLD after lung transplantation is related to the time of onset. CONCLUSIONS: Disease in the thorax and involvement of the allograft are common in the first year after transplantation, but other sites, especially the gastrointestinal tract, predominate later. PTLD that is confined to the allograft appears to have a somewhat better prognosis than disease that involves other sites.

Adult↗
PubMed2001

Outcome of bilateral lung volume reduction in patients with emphysema potentially eligible for lung transplantation.

OBJECTIVE: Between January 1993 and May 1998, we performed 200 consecutive bilateral lung volume reduction operations. After initial assessment, 99 of these patients were eligible for lung volume reduction and potentially eligible for immediate or eventual lung transplantation on the basis of age and absence of contraindications. All chose to proceed with lung volume reduction surgery. The outcomes of these 99 patients are reviewed to assess the consequences of proceeding with lung volume reduction surgery on patients potentially eligible for lung transplantation. METHODS: A retrospective study was performed with the use of a prospectively assembled computer database. RESULTS: The 61 men and 38 women were 55 +/- 7 years old at evaluation for lung volume reduction. Mean values for first second expired volume, total lung capacity, and residual volume were 24% +/- 8%, 141% +/- 19%, and 294% +/- 54% predicted. There were 4 operative deaths and 17 late deaths. Two-year and 5-year survival after evaluation for lung volume reduction are 92% and 75%. The 32 patients who have been listed for transplantation after lung volume reduction include 15 who have undergone transplantation, 14 who remain on the list, and 3 who have been removed from the list. All 15 transplant recipients survived transplantation and 3 have subsequently died of rejection or late infection. The 12 living recipients have a median post-transplantation follow-up of 1.7 years. The age at transplantation was 58 +/- 5 years with transplantation occurring 3.8 +/- 1.1 years after lung volume reduction. Sixteen of 99 patients underwent lower lobe volume reduction with an increased rate of listing (63%, P =.008) and transplantation (38%, P =.003) compared with patients undergoing upper lobe volume reduction. Patients listed for transplantation were younger, more impaired, and experienced less benefit from lung volume reduction than patients not yet listed for transplantation. CONCLUSIONS: The preliminary use of lung volume reduction in patients potentially suitable for transplantation does not appear to jeopardize the chances for subsequent successful transplantation.

Contraindications↗
PubMed2001

Repeatability of quantitative CT indexes of emphysema in patients evaluated for lung volume reduction surgery.

PURPOSE: To evaluate the repeatability of quantitative computed tomographic (CT) indexes of emphysema and the effect of spirometric gating of lung volume during CT in candidates for lung volume reduction surgery (LVRS). MATERIALS AND METHODS: Initial and same-day repeat routine inspiratory spiral chest CT studies were performed in 29 LVRS candidates (group 1, routine study vs repeat study). In a separate cohort of 29 LVRS candidates, spiral chest CT studies were performed both without and with spirometric gating by using a spirometer to trigger scanning at 90% of vital capacity (group 2, spirometric gating study). In each study, Pearson and intraclass correlation coefficients were calculated to determine the agreement between multiple pairs of whole-lung quantitative CT indexes of emphysema, and mean values were compared with two-tailed paired t tests. RESULTS: Pearson and intraclass correlation coefficients were high for all quantitative CT indexes (all > or = 0.92). No significant differences were found between mean values of quantitative CT indexes in group 1. Variation in quantitative CT results was small but more prominent in group 2 than in group 1. The variation in quantitative CT results was primarily related to differences in lung volume (r(2) as great as 0.83). CONCLUSION: Repeatability of quantitative CT test results in LVRS candidates is high and unlikely to improve by using spirometric gating.

Aged↗
PubMed2000

Cost for inpatient care of venous thrombosis: a trial of enoxaparin vs standard heparin.

BACKGROUND: Enoxaparin, a low-molecular-weight heparin administered to hospitalized patients once or twice daily, has shown efficacy and safety equivalent to unfractionated heparin in the treatment of acute venous thromboembolic disease. Although the cost of either enoxaparin regimen is greater than that of unfractionated heparin, the overall cost of care for each of these 3 treatment strategies is unknown. METHODS: A cost minimization analysis of a 3-month, partially blinded, randomized, controlled efficacy and safety trial of anticoagulant therapy for deep vein thrombosis. Three hundred thirty-nine hospitalized patients with symptomatic lower extremity deep vein thrombosis were randomly assigned to initial therapy with subcutaneous enoxaparin either once (n = 112) or twice (n = 123) daily, or with dose-adjusted intravenous unfractionated heparin (n = 104), followed by long-term oral anticoagulant therapy. Estimated 1997 total cost from a third-party payer perspective for the 3-month episode of care was calculated by assigning standard unit costs to counts of medical resources used by each patient in the clinical trial. RESULTS: Average total cost for the 3-month episode of care was similar across all 3 treatment regimens: once-daily dose of enoxaparin, $12,166 (95% confidence interval [CI], $10,744-$13,588); twice-daily dose of enoxaparin, $11,558 (95% CI, $10,201-$12,915); and unfractionated heparin, $12,146 (95% CI, $10,670-$12,622). Bootstrapped estimates and sensitivity analyses did not significantly change findings. CONCLUSIONS: There was no significant difference in the overall cost for the 3-month episode of care for patients treated with either enoxaparin or unfractionated heparin. Additional acquisition costs for anticoagulant medication among patients treated with enoxaparin were offset by savings associated with lower incidence of hospital readmission and shorter duration of venous thromboembolism-related readmissions.

Enoxaparin↗
PubMed2000

Outcome of patients with cystic fibrosis awaiting lung transplantation.

Cystic fibrosis is a common indication for lung transplantation. Under the current organ allocation system, donor lungs are distributed to patients based solely on their accrued waiting time, and the death rate on the waiting list has been high. Physiologic parameters have been used to guide the referral, but risk factors for death while awaiting transplantation have not been well defined. This study aimed to identify factors at the time of evaluation that were associated with death on the waiting list. A consecutive cohort of 146 patients with cystic fibrosis who were listed for lung transplantation was retrospectively reviewed. Characteristics of patients who died awaiting transplantation were compared with those of patients who survived until transplantation or the end of the study. Thirty-seven patients died while waiting, 76 underwent transplantation, and 33 were alive and still waiting. Actuarial survival rates for the entire cohort were 81% at 1 yr, 67% at 2 yr, and 59% at 3 yr. Although a multivariate Cox proportional hazards model (chi(2) = 29.6; p < 0.001) identified shorter six-minute walk distance (50 m increments; RR, 0.69; 95% CI, 0.57 to 0.84), higher systolic pulmonary artery pressure (5 mm Hg increments; RR, 1.41; 95% CI, 1.11 to 1.80), and diabetes mellitus (RR, 1.57; 95% CI, 1.06 to 2.32) as significant risk factors for death on the waiting list, these factors and other features overlapped considerably between the group of patients who died waiting and the group who lived until transplantation or the end of the study. The transplant evaluation selects a rather homogeneous cohort of patients for the waiting list. Unless outcome on the waiting list can be reliably predicted, establishing criteria to allocate donor lungs according to medical urgency may not be feasible.

Adult↗
PubMed2000

Patient selection for lung volume reduction surgery: An objective model based on prior clinical decisions and quantitative CT analysis.

OBJECTIVES: We used whole-lung quantitative CT analysis (QCT)-an objective method of evaluating emphysema severity and distribution based on measurement of lung density-to determine whether subjective selection criteria for lung volume reduction surgery are applied consistently and to model the patient selection process, and assessed the relationship of the model to postoperative outcome. DESIGN: Logistic regression analysis using QCT indexes of emphysema and preoperative physiologic test results as the independent variables, and the decision to operate as the dependent variable. SETTING: University hospital. PATIENTS: Seventy patients selected for bilateral lung volume reduction surgery and 32 otherwise operable patients excluded from surgery based on subjective assessment of emphysema morphology on chest radiography, CT, and perfusion scintigraphy. INTERVENTION: Bilateral lung volume reduction surgery in the selected group. MEASUREMENTS AND RESULTS: Emphysema in patients selected for surgery was more severe overall and in the upper lungs by multiple QCT indexes (p < 0.01, unpaired two-tailed t test). Physiologic abnormalities were slightly more severe in selected patients (p < 0.05, unpaired two-tailed t test). The range of many QCT and physiologic values overlapped considerably between the selected and excluded groups. The percent severe emphysema (<- 960 Hounsfield units [HU]), upper/lower lung emphysema ratio (- 900 HU threshold), and residual volume were the key variables in the model predicting selection decisions (model r(2) = 0.48; p < 0.0001). The model correctly predicted selection decisions in 87% of all cases, 91% of the selected group, and 78% of the excluded group. Surgical patients with a higher model-derived probability of selection had greater postoperative improvement in FEV(1) and 6-min walk distance. CONCLUSIONS: Radiologic selection criteria are applied consistently to the majority of patients. QCT features are strongly associated with selection decisions, are related to outcome, and may help improve consistency and confidence in patient selection.

Adult↗
PubMed2000

Medical and surgical treatment of parapneumonic effusions : an evidence-based guideline.

OBJECTIVE: A panel was convened by the Health and Science Policy Committee of the American College of Chest Physicians to develop a clinical practice guideline on the medical and surgical treatment of parapneumonic effusions (PPE) using evidence-based methods. OPTIONS AND OUTCOMES CONSIDERED: Based on consensus of clinical opinion, the expert panel developed an annotated table for evaluating the risk for poor outcome in patients with PPE. Estimates of the risk for poor outcome were based on the clinical judgment that, without adequate drainage of the pleural space, the patient with PPE would be likely to have any or all of the following: prolonged hospitalization, prolonged evidence of systemic toxicity, increased morbidity from any drainage procedure, increased risk for residual ventilatory impairment, increased risk for local spread of the inflammatory reaction, and increased mortality. Three variables, pleural space anatomy, pleural fluid bacteriology, and pleural fluid chemistry, were used in this annotated table to categorize patients into four separate risk levels for poor outcome: categories 1 (very low risk), 2 (low risk), 3 (moderate risk), and 4 (high risk). The panel's consensus opinion supported drainage for patients with moderate (category 3) or high (category 4) risk for a poor outcome, but not for patients with very low (category 1) or low (category 2) risk for a poor outcome. The medical literature was reviewed to evaluate the effectiveness of medical and surgical management approaches for patients with PPE at moderate or high risk for poor outcome. The panel grouped PPE management approaches into six categories: no drainage performed, therapeutic thoracentesis, tube thoracostomy, fibrinolytics, video-assisted thoracoscopic surgery (VATS), and surgery (including thoracotoiny with or without decortication and rib resection). The fibrinolytic approach required tube thoracostomy for administration of drug, and VATS included post-procedure tube thoracostomy. Surgery may have included concomitant lung resection and always included postoperative tube thoracostomy. All management approaches included appropriate treatment of the underlying pneumonia, including systemic antibiotics. Criteria for including articles in the panel review were adequate data provided for >/=20 adult patients with PPE to allow evaluation of at least one relevant outcome (death or need for a second intervention to manage the PPE); reasonable assurance provided that drainage was clinically appropriate (patients receiving drainage were either category 3 or category 4) and drainage procedure was adequately described; and original data were presented. The strength of panel recommendations on management of PPE was based on the following approach: level A, randomized, controlled trials with consistent results or individual randomized, controlled trial with narrow confidence interval (CI); level B, controlled cohort and case control series; level C, historically controlled series and case series; and level D, expert opinion without explicit critical appraisal or based on physiology, bench research, or "first principles." EVIDENCE: The literature review revealed 24 articles eligible for full review by the panel, 19 of which dealt with the primary management approach to PPE and 5 with a rescue approach after a previous approach had failed. Of the 19 involving the primary management approach to PPE, there were 3 randomized, controlled trials, 2 historically controlled series, and 14 case series. The number of patients included in the randomized controlled trials was small; methodologic weaknesses were found in the 19 articles describing the results of primary management approaches to PPE. The proportion and 95% CI of patients suffering each of the two relevant outcomes (death and need for a second intervention to manage the PPE) were calculated for the pooled data for each management approach from the 19 articles on the primary management approach. (ABST

Adult↗
PubMed1999

Diagnosis of pulmonary embolism with spiral computed tomography and magnetic resonance angiography.

Radiologic imaging techniques such as contrast-enhanced spiral computed tomography (CT) and magnetic resonance (MR) angiography provide noninvasive means of diagnosing pulmonary thromboembolic disease. In addition, both techniques permit direct visualization of the embolus. Although imperfect, both CT and MR angiography in various circumstances fit diagnostic pathways for pulmonary embolism detection. Recent advances in both CT (multidetector ring spiral units and electron beam) and MR technology allow not only depiction of the pulmonary arteries, but also are capable of providing information about the lower extremity deep venous system in a single examination.

Contrast Media↗
PubMed1999

Normal lung function in subjects heterozygous for surfactant protein-B deficiency.

Inherited deficiency of surfactant protein-B (SP-B) is a fatal autosomal recessive disorder of lung cell metabolism caused most frequently by a frameshift mutation in codon 121 of the SP-B gene (121ins2) and is characterized by rapidly progressive respiratory failure immediately after birth. Lungs from genetically engineered heterozygous SP-B-deficient mice exhibit decreased compliance and mild air trapping. To determine whether pulmonary function of heterozygous SP-B-deficient humans is similarly affected, we studied nine heterozygous subjects 16 to 44 yr of age and two unaffected subjects 7 and 23 yr of age from five families of 121ins2 SP-B-deficient infants. An increase in residual volume was noted in one heterozygous family member and one unaffected family member. Compliance, maximal transpulmonary pressure, air flow, and gas exchange were normal in all heterozygous subjects tested. These data suggest that humans heterozygous for the 121ins2 mutation have normal pulmonary function through the first four decades of life. The impact of advancing age and environmental exposures on the lung function of heterozygotes remains to be determined.

Adolescent↗
PubMed1999

Criteria for outpatient management of proximal lower extremity deep venous thrombosis.

STUDY OBJECTIVES: To develop and to evaluate selection criteria for outpatient management of deep venous thrombosis (DVT). DESIGN: We developed outpatient treatment eligibility criteria that incorporated demographic and clinical data. We aimed to exclude patients at high risk for bleeding or recurrent clotting, as well as those with pulmonary embolism, limited cardiopulmonary reserve, or need for hospitalization due to another illness. Then, we retrospectively applied the criteria to hospitalized patients with newly diagnosed proximal lower extremity DVT to determine the fraction of patients eligible for outpatient therapy; patients were classified as eligible, possibly eligible, or ineligible for home treatment based on the selection criteria. SETTING: University hospital. PATIENTS: One hundred ninety-five hospitalized patients diagnosed as having proximal lower extremity DVT by duplex ultrasound over a 1-year period. MEASUREMENTS: Frequency of complications during initial DVT therapy, including major bleeding, symptomatic thromboembolism, and death. RESULTS: Eighteen (9%) patients were classified as eligible, and 18 (9%) were classified as possibly eligible for outpatient therapy. None of these patients developed complications. Of the 159 (82%) patients classified as ineligible, 13 (8%; 95% confidence interval [CI], 4 to 12%) died or developed serious complications. Therefore, the eligibility criteria had a sensitivity of 100% (95% CI, 92 to 100%) and a negative predictive value of 100% (95% CI, 92 to 100%) for predicting serious complications. CONCLUSIONS: Specific eligibility criteria may identify a subset of patients with acute DVT who can be treated safely at home.

Acute Disease↗
PubMed1999

Modification of pleural fluid pH by local anesthesia.

BACKGROUND: It is a common practice to anesthetize patients before performing a thoracentesis. We postulated that this technique may cause a clinically significant difference in the pH of the pleural fluid. METHODS: We compared two methods of determining pleural fluid pH. Fifty patients undergoing diagnostic or therapeutic thoracentesis were enrolled. Two 4-mL aliquots of pleural fluid were anaerobically collected into blood gas syringes containing heparin, one before (group A) and the other after (group B) anesthetizing the patient with 5 mL of 2% mepivacaine. pH was then determined on both samples using an arterial blood gas machine. Agreement analysis was performed overall and in subcategories of pH used to define complicated (<7.1), borderline (7.1 to 7.3), or uncomplicated (>7.3) parapneumonic effusions. We analyzed these same data stratified by the volume of pleural fluid in relationship to the size of the hemithorax (<15% and >15%). RESULTS: There was a statistical difference between the mean pH in both groups (group A, 7.32; group B, 7.28; p<0.0001). There was a significant correlation between the two measures (r = 0.97; p<0.0001). Using the pH subcategories, there was 45% discordance in classification for patients with parapneumonic effusions. The pH values obtained in group B wrongly predicted whether the patient required a chest tube in two of four cases (50%). In patients with effusions that occupied <15% of the affected hemithorax, there was an 80% discordance in classification for patients with parapneumonic effusions, and the pH values obtained in group B wrongly predicted whether the patient required a chest tube in two of two cases (100%). CONCLUSIONS: Local anesthesia is typically used before thoracentesis is performed. However, in cases of suspected parapneumonic effusions that occupy <15% of the affected hemithorax, pH results may be significantly altered by use of local mepivacaine anesthesia.

Adult↗
PubMed1998

Outcome of Medicare patients with emphysema selected for, but denied, a lung volume reduction operation.

BACKGROUND: Lung volume reduction operation shows promise in relieving symptoms and improving function in highly selected patients with emphysema. Withdrawal of Medicare funding for patients selected for operation by standard criteria created a matched control group with which to compare lung volume reduction recipients. METHODS: A retrospective study was done comparing 22 volume reduction candidates denied operation with 65 contemporaneous and comparable volume reduction recipients. Baseline physiologic characteristics were compared and longitudinal measures of pulmonary function were followed up for 24 months. RESULTS: Patients denied operation were similar to volume reduction recipients in all baseline measurements. Patients denied operation experienced a progressive worsening of their function, whereas volume reduction patients experienced sustained improvements. Absolute survival to date is 82% for the surgical group and 64% for the medical group. CONCLUSIONS: The improvement seen in volume reduction patients cannot be attributed to the effects of patient selection or preoperative and postoperative rehabilitation.

Aged↗
PubMed1998

Preoperative and postoperative imaging in the surgical management of pulmonary emphysema.

For patients with emphysema, imaging studies have been useful for diagnostic purposes and for preoperative patient selection for surgical intervention, such as bullectomy, lung transplantation, and LVRS. Chest radiography is useful in evaluating hyperinflation. Inspiratory and expiratory films are used to estimate diaphragmatic excursion and air-trapping. CT scan is used to evaluate the anatomy and distribution of emphysema throughout the lungs, providing information clinically unobtainable by other means. Both imaging techniques are useful for detecting other disease processes. Radionuclide lung scanning also provides an estimate of target areas, volume occupying but nonfunctioning lung. Cohort studies utilizing these imaging techniques have demonstrated associations between preoperative characteristics and postoperative outcome. The imaging studies, especially the chest radiograph, have also played an important role in postoperative management. Many other imaging options are available, such as HRCT scan, quantitative CT scan, and single photon emission CT scan. Other techniques, such as MR imaging, may play a future role as well.

Cohort Studies↗
PubMed1998

MR analysis of lung volume and thoracic dimensions in patients with emphysema before and after lung volume reduction surgery.

OBJECTIVE: This study was performed to assess the accuracy of determining lung volume in patients with emphysema using MR imaging and then to investigate changes in thoracic dimensions after lung volume reduction surgery. SUBJECTS AND METHODS: Fast gradient-echo breath-hold MR imaging through the entire thorax at full inspiration and expiration was performed in 21 patients with severe emphysema and was performed again in nine of the patients who underwent surgery. Lung volumes were determined using a semiautomated computerized method of delineating the lungs and summing cross-sectional areas. These summed areas were compared with volumes measured on plethysmography and CT. Postoperative changes in thoracic structure were determined by measuring anteroposterior and transverse lung dimensions and lung height before and after surgery. RESULTS: The correlation coefficients and SEM for determining inspiratory lung volume were MR imaging versus plethysmography, r = .77, SEM = -12% (volume measured as less on MR imaging); CT versus plethysmography, r = .86, SEM = -13% (volume measured as less on CT); and MR imaging versus CT, r = .87, SEM = 4% (volume measured as greater on MR imaging). The correlation coefficients and SEM for determining expiratory volume on MR imaging versus plethysmography were r = .77, SEM = 6% (volume measured as greater on MR imaging). After surgery, decreases were found in all thoracic dimensions, and such decreases were greatest at expiration. CONCLUSION: MR measurements of lung volume are comparable with those of CT and differ from those of plethysmography. Changes in thoracic dimensions after lung volume reduction surgery are consistent with improved respiratory mechanics.

Adult↗
PubMed1997

Evaluation and preoperative management of lung volume reduction surgery candidates.

The efficacy of lung volume reduction surgery has been demonstrated by improvements in functional status, dyspnea, pulmonary function, alveolar gas exchange, and exercise tolerance. However, surgery has a significant morbidity, mortality, and cost. Surgical outcome is dependent on the clinical, anatomical, and physiological features of the patients and their emphysema. Therefore, the patient evaluation process and the preoperative optimization of medical therapy are crucial for success. Through understanding mechanisms for improvement have added insight to the selection process, patient selection needs further clarification.

Algorithms↗