Biomedical subjects
V F Tapson
Publications and source records attributed to V F Tapson.
Pulmonary embolism--new diagnostic approaches.
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A case of disseminated infection with Nocardia brasiliensis in a lung transplant recipient.
BACKGROUND: Infection with Nocardia species is an increasingly recognized complication of solid organ transplantation. Nocardia asteroides accounts for most transplant-related nocardiosis, while Nocardia brasiliensis rarely causes infection in organ transplant recipients. METHODS: We describe a case of disseminated infection with N brasiliensis in a single-lung transplant recipient who also had concomitant infections with viral and fungal organisms. RESULTS: Although the mortality rate is high in immunocompromised patients with disseminated Nocardia infection, our patient responded favorably to prolonged antimicrobial therapy. CONCLUSIONS: This case illustrates that N brasiliensis, like N asteroides, produces pulmonary disease and dissemination in solid organ transplant recipients, and demonstrates the utility of prolonged treatment with trimethoprim-sulfamethoxazole in Nocardia infections.
Effects of long-term infusion of prostacyclin (epoprostenol) on echocardiographic measures of right ventricular structure and function in primary pulmonary hypertension. Primary Pulmonary Hypertension Study Group.
BACKGROUND: Right heart failure is an important cause of morbidity and mortality in primary pulmonary hypertension. In a recent prospective, randomized study of severely symptomatic patients, treatment with prostacyclin (epoprostenol) produced improvements in hemodynamics, quality of life, and survival. This article describes the echocardiographic characteristics of participants in this trial; the relationship of echocardiographic variables to hemodynamic parameters, exercise capacity, and quality of life; and the echocardiographic changes associated with prostacyclin therapy. METHODS AND RESULTS: The 81 patients enrolled in this multicenter trial were randomized to treatment with a long-term infusion of prostacyclin in addition to conventional therapy (n = 41) or conventional therapy alone (n = 40) for 12 weeks. Echocardiograms and assessments of hemodynamics, exercise capacity, and quality of life were performed before and after the treatment phase. On baseline evaluation, patients had marked right ventricular dilatation and dysfunction, abnormal septal curvature, and significant tricuspid regurgitation with a high regurgitant velocity. Pericardial effusions were common. More pronounced abnormalities in right heart structure and function were associated with higher pulmonary arterial and mean right atrial pressures, lower cardiac index, and impaired exercise capacity but had no predictable relationship to quality-of-life indicators. The 12-week infusion of prostacyclin had beneficial effects on right ventricular size, curvature of the interventricular septum, and maximal tricuspid regurgitant jet velocity. CONCLUSIONS: The echocardiographic manifestations of severe primary pulmonary hypertension reflect abnormalities in hemodynamics and exercise capacity. Prostacyclin has beneficial effects on right heart structure and function that may contribute to the clinical improvement and prolonged survival observed with this drug.
New imaging techniques for the diagnosis of pulmonary embolism.
Pulmonary embolism (PE) remains a common cause of illness and death. Appropriate therapy requires timely diagnosis, but the currently available noninvasive diagnostic methods lack adequate sensitivity and specificity. In particular the vast majority of ventilation-perfusion scans are unable to confirm or reliably exclude PE, cannot differentiate between acute and chronic PE, and provide no clues about possible alternate explanations of presenting symptoms (even if PE can be excluded). Although the precise role of these scans in the diagnosis of PE remains to be clarified, recent advances appear to ensure a place for magnetic resonance imaging and helical computed tomography in the diagnostic evaluation of PE in the near future.
Telescoping bronchial anastomoses for unilateral or bilateral sequential lung transplantation: CT appearance.
PURPOSE: To determine the computed tomographic (CT) appearance of telescoping bronchial anastomoses. MATERIALS AND METHODS: CT scans obtained in 36 adult patients with 54 telescoping anastomoses (30 right bronchus, 24 left bronchus) were retrospectively reviewed. Seventeen scans were obtained with 10-mm collimation, one with 5-mm collimation, and 18 with 3-mm collimation. Multiplanar volume reconstruction images were retrospectively generated in 19 patients. CT findings were correlated with fiberoptic bronchoscopic findings and clinical records. RESULTS: Smooth, spherical air collections caused by diverticula of redundant mucosa were seen at the inferior or medial aspect of 22 anastomoses (41%). Endoluminal flaps and linear air collections caused by separation of the invaginated bronchus from the recipient bronchus were seen in 16 anastomoses (30%). Flaps and linear air collections were seen only at the anterior, superior, or inferior aspects of the anastomosis. Flaps and diverticula were more common at right anastomoses than at left anastomoses. No patient with an endoluminal flap or diverticulum at CT had dehiscence at bronchoscopy. Irregular air collections or posterior wall defects were suggestive of dehiscence at four anastomoses (7%). Dehiscence was confirmed bronchoscopically at two of these four anastomoses. CONCLUSION: Endoluminal flaps and linear or spherical air collections can be a normal feature of the telescoping anastomosis and should not necessarily be interpreted as dehiscence.
Pharmacologic hemodynamic support in massive pulmonary embolism.
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Iron accumulation in lung allografts after transplantation.
Lung transplantation has become a therapeutic option for end-stage pulmonary diseases, but after transplantation, infections and obliterative bronchiolitis (OB) are major causes of long-term morbidity and mortality. OB is a fibroproliferative disease, of poorly understood etiology, characterized by an irreversible decline in allograft function. Because diseases with tissue iron overload are characterized by fibrosis and end-organ failure, we studied the iron concentrations in BAL fluid and lung tissue in 10 lung allograft patients. BAL fluid revealed significantly elevated iron concentrations in allograft patients compared with five normal volunteers (135+/-16.54 micromol/L vs 33.65+/-7.48 micromol/L, respectively). Prussian blue staining of biopsy specimens of lung allograft tissue revealed an accumulation of iron primarily in alveolar macrophages. Immunohistochemical stains for ferritin revealed accumulation of the protein in macrophages, interstitium, vascular walls, and bronchiolar epithelium. Iron studies of the blood (serum ferritin and iron concentrations) revealed no evidence for systemic iron overload. In conclusion, patients with pulmonary allografts appear to have elevated concentrations of iron in lung tissue. This iron overload may place the allografts at increased risk of metal-mediated injury and fibrosis.
Pulmonary embolism: the diagnostic repertoire.
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Radiologic issues in lung transplantation for end-stage pulmonary disease.
Lung transplantation has evolved into an effective therapy for end-stage pulmonary disease. The radiologist has an important role in the management of these patients before and after transplantation. Unfortunately, the radiologic findings of the major complications (i.e., reperfusion edema, infection, rejection) that occur after transplantation overlap and are often nonspecific. Clinical correlation, bronchoalveolar lavage, and transbronchial biopsy are usually required for accurate differentiation. The following rules of thumb may be helpful: Radiographic opacities seen during the first week are usually due to reperfusion edema: persistent or progressive opacities beyond the first week suggest infection or acute rejection: infection in the first month is usually bacterial, and opportunistic pneumonia is more common thereafter, nodular opacities are usually due to infection or posttransplantation lymphoproliferative disorders but can also be due to transbronchial lung biopsy; and progressive bronchial dilatation and air trapping seen on expiratory CT are useful signs of BOS.
A comparison of continuous intravenous epoprostenol (prostacyclin) with conventional therapy for primary pulmonary hypertension.
BACKGROUND: Primary pulmonary hypertension is a progressive disease for which no treatment has been shown in a prospective, randomized trial to improve survival. METHODS: We conducted a 12-week prospective, randomized, multicenter open trial comparing the effects of the continuous intravenous infusion of epoprostenol (formerly called prostacyclin) plus conventional therapy with those of conventional therapy alone in 81 patients with severe primary pulmonary hypertension (New York Heart Association functional class III or IV). RESULTS: Exercise capacity was improved in the 41 patients treated with epoprostenol (median distance walked in six minutes, 362 m at 12 weeks vs. 315 m at base line), but it decreased in the 40 patients treated with conventional therapy alone (204 m at 12 weeks vs. 270 m at base line; P < 0.002 for the comparison of the treatment groups). Indexes of the quality of life were improved only in the epoprostenol group (P < 0.01). Hemodynamics improved at 12 weeks in the epoprostenol-treated patients. The changes in mean pulmonary-artery pressure for the epoprostenol and control groups were -8 percent and +3 percent, respectively (difference in mean change, -6.7 mm Hg; 95 percent confidence interval, -10.7 to -2.6 mm Hg; P < 0.002), and the mean changes in pulmonary vascular resistance for the epoprostenol and control groups were -21 percent and +9 percent, respectively (difference in mean change, -4.9 mm Hg/liter/min; 95 percent confidence interval, -7.6 to -2.3 mm Hg/liter/min; P < 0.001). Eight patients died during the study, all of whom had been randomly assigned to conventional therapy (P = 0.003). Serious complications included four episodes of catheter-related sepsis and one thrombotic event. CONCLUSIONS: As compared with conventional therapy, the continuous intravenous infusion of epoprostenol produced symptomatic and hemodynamic improvement, as well as improved survival in patients with severe primary pulmonary hypertension.
Glutathione depletion in epithelial lining fluid of lung allograft patients.
The lower respiratory tract is protected against reactive oxygen species (ROS) by a complex antioxidant system. In the epithelial lining fluid (ELF), glutathione (L-alpha-glutamyl-L-cysteinylglycine, GSH) is essential for adequate protection of pneumocytes from potential toxicity mediated by extracellular hydrogen peroxide (H2O2). We assessed the concentration of total GSH in bronchoalveolar lavage fluid (BALF) in lung allograft patients in the absence and presence of acute rejection. Bronchoalveolar lavage (BAL) and biopsies were performed concurrently on 36 occasions in 17 patients who had undergone lung transplantation. BALF samples were divided into two groups on the basis of presence or absence of acute lung rejection on transbronchial biopsy. Seven BALF samples were obtained from control subjects for comparison. The BALF data demonstrated significantly lymphocyte recruitment and evidence of lung injury during acute rejection episodes. Transplant allografts without rejection showed significant depletion of total GSH in the ELF as compared with that of normal volunteers (94.0 +/- 9.7 microM versus 302.6 +/- 40.8 microM, p < 0.01). Transplant allografts with acute rejection had a slightly higher GSH concentration in their ELF (179.8 +/- 34.7), but this was still lower than control values. The deficiency of total GSH in the alveolar fluid may predispose lung allografts to extracellular H2O2-mediated toxicity.
Delayed right heart failure following lung transplantation.
Dynamic right ventricular outflow tract obstruction (RVOTO) has been reported following lung transplantation for pulmonary hypertension, usually in association with the use of inotropic agents. This report describes delayed severe right-sided heart failure associated with right ventricular outflow tract obstruction following sequential bilateral lung transplantation and closure of a ventricular septal defect. The patient had no evidence of outflow tract obstruction in the early posttransplant period but developed progressive right heart failure more than 2 months later. Catheterization revealed dynamic RVOTO and an elevated right ventricular end-diastolic pressure. The patient was treated with metoprolol tartrate and diltiazem hydrochloride with resolution of the outflow tract obstruction and heart failure. This case demonstrates that RVOTO can occur in the late posttransplant period and must be included in the differential diagnosis for patients who develop right-sided heart failure.
Diagnostic yield of bronchoscopies after isolated lung transplantation.
Lung transplantation has become an acceptable therapeutic option for end-stage pulmonary diseases. The most common causes of long-term mortality after transplantation are infections and obliterative bronchiolitis (OB). While acute rejection has been shown to be associated with an increased risk of development of OB, cytomegalovirus (CMV) pneumonitis is more controversial as a risk factor for OB. Surveillance bronchoscopies are therefore advocated as a method of detecting silent episodes of CMV pneumonitis or acute rejection. We performed 226 bronchoscopies in 43 lung transplant recipients over 34 months. One hundred fifty-seven of the 226 bronchoscopies were performed according to a surveillance protocol. Acute rejection was diagnosed if lung histologic study revealed grade 2 to 4 rejection or if prompt reversal of clinical deterioration occurred after initiation of pulse steroid therapy. CMV pneumonitis was diagnosed when transbronchial biopsy histologic specimens revealed evidence of CMV inclusion bodies, or when CMV was recovered on BAL fluid in the presence of allograft deterioration. The proportion of patients who were free from any episode of acute rejection or CMV pneumonitis after transplantation was determined by Kaplan-Meier analysis. Twenty-one percent of our transplant recipients were free from acute rejection or CMV pneumonitis after a mean follow-up of 13 months. All patients who had acute rejection or CMV pneumonitis had the initial episode in the first 4 months after transplantation. Patients free of acute rejection or CMV pneumonitis 4 months after transplantation continued to be event free for the duration of follow-up. Our data suggest that surveillance bronchoscopy can be aborted in patients who are free from acute rejection or CMV pneumonitis by 4 months after transplantation. The role of surveillance bronchoscopy in decreasing the incidence of OB or improving survival can be determined only by future randomized prospective trials.
ICU stay after single lung transplantation.
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Recurrence of diffuse panbronchiolitis after lung transplantation.
Diffuse panbronchiolitis (DBP) is characterized by chronic inflammation of the upper and lower respiratory tract. DPB has been found almost exclusively in oriental populations. We describe the occurrence of a case of DPB in an African American patient who underwent bilateral sequential lung transplantation. Ten weeks after transplantation, DPB recurred in the lung allograft, with rapid and significant deterioration in graft function. Allograft function improved within a few weeks after beginning treatment with erythromycin. This early recurrence is suggestive of a systemic etiology of DPB. Although recurrence of other systemic diseases has been reported after lung transplantation, no previous patients have been reported with early functional deterioration based solely on disease recurrence.
Management of venous thromboembolic disease. The impact of low-molecular-weight heparin.
Prophylaxis for DVT unequivocally is beneficial in patients identified to be at high risk. Heparin prophylaxis with subcutaneous low-dose UFH is adequate in some clinical settings but less effective in others. LMWH preparations are effective and safe as prophylaxis in certain medical patients as well as in general surgery and elective hip replacement. Efficacy and safety are demonstrated in the therapy of established venous thromboembolism. Subcutaneous administration of LMWH once or twice daily may prove more convenient from both the patient and nursing viewpoint, particularly in the treatment of established DVT. Monitoring is not necessary when using LMWH preparations as prophylaxis, and a fixed-dose without weight adjustment has been used in most prophylaxis trials. When treating established DVT, less monitoring is likely to be required than currently is the case with UFH. Although the cost of LMWH preparations is greater than that of UFH, the decrease in the occurrence or recurrence of thromboses that has been demonstrated in some trials might prove an effective balance. Future avenues to explore include discovery of better means to standardize the LMWH preparations and determination of the efficacy and safety of LMWH in specific populations, such as those in intensive care units, cancer patients, nursing home patients, and outpatients in general. Although cost-benefit is favorable thus far, meticulous assessment in other settings may enhance the acceptance of these agents. Long-term follow-up could be helpful in determining the relative effect of different heparin preparations on the frequency of postphlebitic syndrome. Comparison of different LMWH fractions may follow, as well as further investigations of newer ultra-low-molecular-weight agents. One LMWH preparation (enoxaparin) already has been approved in the United States for prophylaxis in the setting of elective hip replacement; and dalteparin has been approved here for use as DVT prophylaxis in patients undergoing abdominal surgery when there appears to be a significant risk of thromboembolism. It is likely that LMWH preparations will become even more widely used in North America and that the approved indications will expand to include prophylaxis in numerous settings and the treatment of established venous thromboembolism.