Obliterative Bronchiolitis

Constrictive bronchiolitis after treatment of colon cancer with 5-fluorouracil

Constrictive bronchiolitis (CB) is a rare disease with unclear etiology. We report a 37-year-old female with CB who developed progressive dyspnea and cough after completing a course of 5-fluorouracil (5-FU) for colon cancer. The patient had evidence of irreversible obstructive lung disease and lung biopsy showed typical findings of chronic inflammation, submucosal thickening and obliteration of bronchioles. To the best of our knowledge this is the first reported case of CB after treatment with 5-FU.

Bronchiolitis obliterans after allogenic bone marrow transplantation: HRCT findings

Objective

To evaluate the high resolution computed tomography (HRCT) findings of bronchiolitis obliterans (BO) after bone marrow transplantation (BMT).

Materials and Methods

During the past three years, 11 patients were diagnosed as having BO after BMT when they developed irreversible air flow obstruction, with an FEV₁ value of less than 80% of the baseline value, without any clinical evidence of infection. All 11 patients underwent HRCT, of whom eight also underwent follow-up HRCT. The HRCT images were assessed retrospectively for the presence of decreased lung attenuation, segmental or subsegmental bronchial dilatation, diminution of peripheral vascularity, centrilobular nodules, and branching linear structure on the inspiratory images. The lobar distribution of the decreased lung attenuation and bronchial dilatation was also examined. The presence of air trapping was investigated on the expiratory images. The interval changes of the HRCT findings were evaluated in those patients who had follow-up images.

Results

Abnormal HRCT findings were present in all cases; the most common abnormalities were decreased lung attenuation (n=11), subsegmental bronchial dilatation (n=6), diminution of peripheral vascularity (n=6), centrilobular nodules or branching linear structure (n=3), and segmental bronchial dilatation (n=3). Expiratory air trapping was noted in all patients. The decreased lung attenuation and bronchial dilatations were more frequent or extensive in the lower lobes. Interval changes were found in all patients with follow-up HRCT: increased extent of decreased lung attenuation (n=7); newly developed or progressed bronchial dilatation (n=4); and increased lung volume (n=3).

Conclusion

HRCT scans are abnormal in patients with BO, with the most commonly observed finding being areas of decreased lung attenuation. While the HRCT findings are not specific, it is believed that their common features can assist in the diagnosis of BO in BMT recipients.

Role of CMV pneumonia in the development of obliterative bronchiolitis in heart-lung and double-lung transplant recipients

Obliterative bronchiolitis (OB) is the main cause of late mortality after lung transplantation. Cytomegalovirus infection has been associated with late graft failure. The aim of this study was to determine whether the development of OB was related to CMV pretransplant serological status and to CMV infections. The study group comprised 36 lung transplant recipients (27 HLT and 9 DLT) who survived more than 4 months, of whom 47% developed OB (defined by the persistence of an unexplained obstructive disease: FEV1/VC < 0.7). OB occurred more frequently: (1) in seronegative recipients with seropositive donors (8/9) than in seropositive recipients (7/19) or seronegative well-matched recipients (2/8); and (2) in patients who experienced CMV pneumonia (11/16) and CMV recurrence (11/16). Since matching seronegative recipients is the best way to prevent CMV infection, we believe that seronegative grafts must be reserved for seronegative recipients.

IL-16 in the airways of lung allograft recipients with acute rejection or obliterative bronchiolitis

Acute rejection (AR) is the principal risk factor for obliterative bronchiolitis (OB), the major complication of lung transplantation. It is known that activated CD4+ T lymphocytes are involved in the development of AR and that interleukin (IL)-16 can inhibit the activity of CD4+ T lymphocytes. In this study, we evaluated whether the concentration of IL-16 in the airways is altered in AR or OB and, if so, how this IL-16 concentration relates to the number or activity of airway lymphocytes. The concentration of IL-16 protein was measured in bronchoalveolar lavage (BAL) fluid at three time-points in lung allograft recipients with either AR or OB and in matched controls using ELISA. The concentration of soluble IL-2 receptor (R) protein was measured in BAL fluid using ELISA as well, as an indicator of lymphocyte activity. The percentage of airway lymphocytes was evaluated by performing BAL differential cell counts. Lung allograft recipients with AR displayed lower IL-16 concentrations compared with matched control patients and this IL-16 concentration correlated negatively with the sIL-2R concentration, but it did not correlate with the percentage of lymphocytes in BAL fluid. In contrast, in BAL fluid from lung allograft recipients with OB, the IL-16 concentration was not altered compared with matched control patients and it did not correlate with the percentage of lymphocytes or with the sIL-2R concentration. These data are compatible with an increase in IL-16 playing a protective role against AR but not against OB and, hypothetically, this type of protective effect could be exerted via a down-regulation of the activity of T lymphocytes.

Imaging of lung transplantation

Lung transplantation is an accepted treatment for a large number of end-stage pulmonary diseases. There are several complications that pertain specifically to lung transplant recipients, including airway ischemia, reperfusion edema, infections, acute rejection, obliterative bronchiolitis, and other postoperative problems relating to surgical technique and immuno-suppressive therapy. Imaging procedures play an important role in the diagnosis and management of these problems.

Aerosol bolus dispersion in patients with bronchiolitis obliterans after heart-lung and double-lung transplantation. The Munich Lung Transplantation Group

Bronchiolitis obliterans (BO) is one of the main late complications in patients after lung transplantation. Because BO is located in small airways, conventional lung function tests are supposed to be rather insensitive to detect early stages of this disease. In this study, the capability of the aerosol bolus dispersion test to detect BO was tested in 12 subjects with heart-lung and double-lung transplantation. Four of these patients had histological evidence of BO. The broadening (dispersion) of inhaled boluses consisting of monodispersed inert test particles during respiration was repeatedly measured in each subject. Additional measurements of spirometric and bodyplethysmographic measurements were performed. Patients with evidence of BO showed significantly increased aerosol bolus dispersion and significantly reduced maximal airflow parameters. Calculation of receiver operating characteristics (ROCs) revealed that from all lung function parameters under consideration, aerosol bolus dispersion divided by the maximum expiratory flow rate at 50% of vital capacity (MEF50) and MEI50 had the highest sensitivity and specificity for the detection of BO. Both parameters showed a sensitivity and specificity of 100%. Therefore, it may be speculated that even in early stages of disease, the combination of MEF50 measurement with aerosol bolus dispersion measurements may be a powerful tool for the detection of BO in patients with lung transplantation.

Constrictive (obliterative) bronchiolitis: diagnosis, etiology, and a critical review of the literature

Constrictive bronchiolitis (CB) (or obliterative bronchiolitis) designates inflammation and fibrosis occurring predominantly in the walls and contiguous tissues of membranous and respiratory bronchioles, with resultant narrowing of their lumens. It differs from bronchiolitis obliterans-organizing pneumonia in its histopathology and clinical course. Most cases of CB occur in the setting of organ transplants, particularly lung and heart-lung transplants, but also in bone marrow transplants. Other bona fide cases are rare: infection, particularly viral infection, appears to be a well-documented precursor to CB in children, but not in immunocompetent adults. Constrictive bronchiolitis also has been reported in the course of rheumatoid arthritis, in certain other autoimmune diseases such as pemphigus vulgaris, after inhalation of toxic gases such as nitrogen oxide, after ingestion of certain drugs or medicinal agents such as Sauropus androgynous, and as a cryptogenic illness. Recent reports suggest that CB, as defined by clinical criteria (that is, bronchiolitis obliterans syndrome), is very common in lung allograft recipients who survive more than 5 years and, although it is associated with significant mortality, it also can be clinically stable. Furthermore, with the current practice of close monitoring of these patients, it appears that CB may now be diagnosed at an earlier stage, at which resolution, or at least stabilization of progression, is possible. A histopathologic diagnosis of CB in lung transplant and other patients may be difficult to make due to the patchy distribution of lesions, the technical difficulty in obtaining tissue in late lesions with extensive fibrosis, and the failure to recognize lesions. With regard to the last of these, in early stages of disease, CB may be subtle and easily missed in routine hematoxylin-eosin-stained specimens, while in advanced stages the disease may be equally difficult to diagnose if the patchy scarring in the lung is interpreted as nonspecific. The relative loss of bronchioles and the relationship of the scars to contiguous arteries should signal the need for elastic stains to look for the residual elastica of the bronchioles amidst the foci of fibrosis. Increasingly, clinical grounds, including pulmonary functions studies and high-resolution computed tomography findings, are proving to be relatively sensitive methods of detecting CB. Finally, the progressive airway destruction in chronic transplantation rejection appears to be a T-cell-mediated process. The "active" form of constrictive bronchiolitis, with attendant lymphocytic inflammation of the airways, likely precedes the "inactive" or scarred form of constrictive bronchiolitis.

Promoting adherence to an electronic home spirometry research program after lung transplantation

Adherence with any long-term treatment or research protocol is a challenge; this has been found to be the case with lung transplant recipients participating in an electronic home spirometry research program. Because the purpose of the current study is to develop a system for detecting early infection and rejection in lung transplant recipients, regular transmission of data by subjects to the research data center is imperative to the success of the study. Various adherence-promoting strategies have been developed by the research team to increase subject adherence with the program. An increased adherence rate has been reported after implementation of these various strategies, yet work remains to promote continually regular participation in the program by all subjects. It remains a challenge for the research team to devise creative and effective strategies for increasing adherence to regular spirometer use to provide data to develop a computerized system for detecting early infection and rejection of transplanted lung tissue.

Obliterative bronchiolitis

Obliterative bronchiolitis following lung transplantation is common and potentially devastating. Its exact cause is undefined, but multiple immune and nonimmune processes contribute to its pathogenesis. Severe acute rejection and recurrent acute rejection have been shown to confer the greatest risk for obliterative bronchiolitis, signifying the central importance of alloimmunity in the disease process. Treatment of established disease with intensification of immune suppression has been of limited benefit, so current clinical strategies include early detection and minimization of risk. As our understanding of the disease evolves, it is hoped that effective interventions targeted at specific pathogenetic steps will emerge. In the meantime, obliterative bronchiolitis remains the most important and sinister long-term complication of lung transplantation.

Perioperative anaesthetic considerations for patients undergoing lung transplantation

PURPOSE

Five thousand, two hundred and eight lung transplants were performed worldwide before April, 1996. This review will discuss lung transplantation from an historical perspective, its indications, donor and recipient selection criteria, donor lung preparation, surgical considerations, perioperative anaesthetic management, and associated morbidity and mortality.

SOURCE

Recent literature on perioperative anaesthetic management of lung transplantation and experience from international centres including the Toronto Lung Transplant Group and the St. Louis Lung Transplant Group.

PRINCIPAL FINDINGS

Lung transplantation comprises of a family of operations, including single lung transplant, bilateral single lung transplant, lobar transplant and block heart-lung transplant. Improved donor lung preservation techniques have increased the duration of cold ischaemic time. The advent of bilateral single lung transplant has decreased the requirement for cardiopulmonary bypass, and airway complications have been reduced by adoption of the telescoping bronchial anastomoses. Advances in perioperative monitoring (including transoesophageal echocardiography), pulmonary vasodilators (e.g., nitric oxide and prostaglandin E1), cardiopulmonary bypass and ventilatory management, and a better understanding of the pathophysiological processes during the procedure have improved perioperative anaesthetic management. Also, advances in broad spectrum antibiotics and immunosuppressant drugs have improved the outcome by better management of the complications of infection and rejection.

CONCLUSION

Lung transplantation improves the quality of life with marginal improvement in life expectancy of the recipients. It is an expensive procedure requiring continued resources for long term management of these patients.

Anaesthesia for patients after lung transplantation

PURPOSE

The purpose of this article is to review the literature on post lung transplant patients presenting for surgery and anaesthesia and to provide insight into their perioperative management.

SOURCE

Articles and books were identified via a Medline search and through a review of the bibliographies of these sources.

PRINCIPLE FINDINGS

Single and double lung transplantation is becoming more common and the period of survival is increasing. As a result, more of these patients are presenting for surgery and anaesthesia. Also, it is increasingly likely that these patients may present, either for emergency or elective surgery, to anaesthetists with limited experience in this field. These patients have considerable medical, physiological and pharmacological problems which need to be understood.

CONCLUSION

Anaesthesia, local, regional, or general, can be safely delivered to these patients provided that the physiology and pathophysiology of the transplanted lung, the pharmacology of the immunosuppressive agents, and the underlying surgical condition are understood.

Living-donor lobar lung transplantation experience: intermediate results

OBJECTIVE

Living-donor lobar lung transplantation offers an alternative for patients with a life expectancy of less than a few months. We report on our intermediate results with respect to recipient survival, complications, pulmonary function, and hemodynamic reserve.

METHODS

Thirty-eight living-donor lobar lung transplants were performed in 27 adult and 10 pediatric patients for cystic fibrosis (32), pulmonary hypertension (two), pulmonary fibrosis (one), viral bronchiolitis (one), bronchopulmonary dysplasia (one), and posttransplantation obliterative bronchiolitis (one). Seventy-six donors underwent donor lobectomies.

RESULTS

There were 14 deaths among the 37 patients, with an average follow-up of 14 months. Predominant cause of death was infection, consistent with the large percentage of patients with cystic fibrosis in our population. The overall incidence of rejection was 0.07 episodes/patient-month, representing 0.8 episodes/patient. Postoperative pulmonary function testing generally showed a steady improvement that plateaued by postoperative months 9 to 12. Fourteen patients who were followed up for at least 1 year underwent right heart catheterization; pressures and pulmonary vascular resistances were within normal ranges. Bronchiolitis obliterans was definitively diagnosed in three patients. Among the 76 donors, complications in the postoperative period included postpericardiotomy syndrome (three), atrial fibrillation (one), and surgical reexploration (three).

CONCLUSIONS

We believe that these data support an expanded role for living-donor lobar lung transplantation. Our intermediate data are encouraging with respect to the functional outcome and survival of these critically ill patients, who would have died without this option.

Single lung transplantation for chronic obstructive pulmonary disease: pulmonary function and impact of bronchiolitis obliterans syndrome

Chronic obstructive pulmonary disease (COPD) is now the most common indication for single lung transplantation. In long-term follow-up, obliterative bronchiolitis is a major problem. The aim of the present study was to perform a long-term follow-up of the pulmonary function and to examine the effect of development of bronchiolitis obliterans syndrome (BOS). Nineteen patients with end-stage COPD underwent single lung transplantation and were followed regularly with pulmonary function tests, and ventilation and perfusion scintigraphy (mean observation time 29 months). They were divided into two categories, with and without BOS, using the definition recommended by the International Society for Heart and Lung Transplantation working group. A mixed model analysis of variance with BOS as co-variate was used to evaluate its effect on pulmonary function. Spirometry, lung transfer factor for carbon monoxide (TLCO), arterial blood gases and 6-min walk test improved significantly (P < 0.001) from before transplantation to 3 months after transplantation. Nine patients developed BOS. Implied by the definition of the syndrome, forced expiratory volume in 1 s (FEV1) was significantly (P < 0.001) lower for patients with BOS while there was no significant effect of BOS category on TLCO corrected for alveolar volume (VA) or perfusion to transplant. Patients without BOS maintained their pulmonary function, and ventilation and perfusion to transplant for more than 3 yr after transplantation. The present results suggest that decreasing FEV1 accompanied by an unchanged TLCO/VA and pulmonary perfusion support the diagnosis of BOS after single lung transplantation for COPD.

Primary pulmonary hypertension as a risk factor for the development of obliterative bronchiolitis in lung allograft recipients

STUDY OBJECTIVES

Obliterative bronchiolitis (OB) is a major factor limiting long-term survival after lung transplantation. The etiology of this disease process remains incompletely understood. Several risk factors have been identified previously, including acute rejection and cytomegalovirus pneumonitis. The purpose of this study was to evaluate primary pulmonary hypertension (PPH) as a potential risk factor for the development of OB after lung transplantation.

DESIGN AND PATIENTS

We retrospectively analyzed 107 lung allograft recipients (28 heart-lung, 18 bilateral sequential single-lung, 61 single-lung) who underwent transplantation between May 1, 1986, and April 30, 1994, and survived at least 3 months posttransplant. Mean follow-up posttransplant was 28.6 months (range, 3.5 to 99 months). Actuarial survival was estimated for patients with or without PPH and for those who did or did not develop OB.

RESULTS

In all, 25 patients (23.4%) developed OB, diagnosed by strict histologic criteria. Of 23 patients with PPH, 9 (39.1%) developed OB, compared with 16 (19.0%) of 84 patients without PPH (p = 0.044). Actuarial survival, sex, time on waiting list, and follow-up posttransplant were not significantly different between groups. PPH was the major determinant for the development of OB (p = 0.0468) when evaluating PPH and cytomegalovirus pneumonitis together as risk factors. Patients with PPH also developed OB significantly earlier posttransplant, compared with patients with other primary disease (p = 0.05).

CONCLUSIONS

Patients with PPH who undergo lung transplantation are at increased risk for the development of OB, which also occurs at a shorter time interval posttransplant. This subgroup needs aggressive monitoring for diagnosis and treatment of OB.

Total lymphoid irradiation for refractory acute rejection in heart-lung and lung allografts

Persistent or recurrent acute allograft rejection (AR) refractory to high-dose steroid therapy can adversely affect long-term outcomes of heart-lung (HLT), bilateral-lung (BLT), and single-lung (SLT) transplantations. The use of total lymphoid irradiation (TLI) for the management of refractory acute AR in six transplant recipients (two men, four women; mean age, 29.8 +/- 3.8 years) is detailed. There are two HLT (primary pulmonary hypertension [PPH], cystic fibrosis [CF]), 1 BLT (pulmonary hypertension postventricular septal defect repair), and 3 SLT (sarcoid, PPH, congenital heart disease with atrial septal defect) recipients. Refractory AR is defined as persistent rejection unresponsive to high-dose steroid therapy in all cases. The BLT and SLT recipients had at least two moderate and one mild AR events per patient. The HLT recipients had at least two moderate acute heart and one severe and one mild asynchronous acute lung rejection events per patient. A total of 800 cGy of total lymphoid irradiation (TLI) was administered over a 5-week period. Mild and transient leukopenia was the only observed side effect. The patient with PPH received TLI 313 days after HLT for recurrent AR at another institution and died of ARDS 4 weeks after completing TLI. The patient with CF received TLI 707 days after HLT and died 457 days after TLI of severe obliterative bronchiolitis (OB) with multiorgan failure. The patient with BLT received TLI 176 days after transplant and died 372 days after TLI of respiratory failure related to severe rejection. One patient with SLT received TLI 78 days after transplant and died 679 days after TLI of severe acute AR. The two remaining patients with SLTs have been free from acute AR for more than 4 years. The patient with sarcoidosis received TLI 37 days after SLT following a clinical rejection event and two severe acute AR events. He is alive with normal lung function 5 years later. The patient with PPH received TLI 108 days after SLT following three moderate acute AR events and is alive with stable OB 4 years later. These limited preliminary results suggest that TLI has merit for the treatment of intractable acute AR following HLT and lung transplantation.

Recurrence of obliterative bronchiolitis and determinants of outcome in 139 pulmonary retransplant recipients

An international series of pulmonary retransplantation was updated to identify the predictors of outcome and the prevalence and recurrence rate of obliterative bronchiolitis after operation. The study cohort included 139 patients who underwent retransplantation in 34 institutions in North America and Europe between 1985 and 1994. Eighty patients underwent retransplantation because of obliterative bronchiolitis, 34 because of acute graft failure, 13 because of intractable airway complications, 8 because of acute rejection, and 4 because of other indications. Survivors were followed up for a median of 630 days, with 48 patients alive at 1 year, 30 at 2 years, and 16 at 3 years after retransplantation. Actuarial survival was 65% +/- 4% at 1 month, 54% +/- 4% at 3 months, 45% +/- 4% at 1 year, 38% +/- 5% at 2 years, and 36% +/- 5% at 3 years; nonetheless, of 90-day postoperative survivors, 65% +/- 6% were alive 3 years after retransplantation. Life-table and univariate Cox analysis revealed that more recent year of retransplantation (p = 0.009), identical match of ABO blood group (p = 0.01), absence of a donor-recipient cytomegalovirus mismatch (p = 0.04), and being ambulatory immediately before retransplantation (p = 0.04) were associated with survival. By multivariate Cox analysis, being ambulatory before retransplantation was the most significant predictor of survival (p = 0.008), followed by reoperation in Europe (p = 0.044). Complete pulmonary function tests were done yearly in every survivor of retransplantation and bronchiolitis obliterans syndrome stages were assigned. Eleven percent of patients were in stage 3 at 1 year, 20% at 2 years, and 25% at 3 years after retransplantation. Values of forced expiratory volume in 1 second decreased from 1.89 +/- 0.13 L early after retransplantation to 1.80 +/- 0.15 L at 1 year and 1.54 +/- 0.16 L at 2 years (p = 0.006, year 2 versus baseline postoperative value). Most of this decrease occurred in patients who underwent retransplantation because of obliterative bronchiolitis, whereas the pulmonary function of patients who underwent retransplantation because of other conditions did not significantly change. We conclude that survival after pulmonary retransplantation is improving. Optimal results can be obtained in patients who are ambulatory before retransplantation. Compared with recent data after primary lung transplantation, bronchiolitis obliterans syndrome does not appear to recur in an accelerated manner after retransplantation. As long as early mortality as a result of infection can be minimized, pulmonary retransplantation appears to offer a reasonable option in highly selected patients.

Bronchiolitis obliterans in single-lung transplant recipients

The presentation and clinical course of bronchiolitis obliterans (BO) in single-lung transplant (SLT) recipients has thus far not been well described. We retrospectively analyzed the serial spirometry of 15 SLT patients with BO. All the patients fulfilled the criteria for BO syndrome, and 11 of the 15 had histologically documented BO. Based on serial FEV1 analysis, we identified three patterns of presentation and progression of BO. The first pattern (n = 6) was characterized by a rapid onset and a relentless progressive course; the second pattern (n = 5) was characterized by a similar rapid onset and initial rapid decline, but was followed by stabilization in lung function; the third pattern (n = 4) was characterized by an insidious onset and course. In all patients, a permanent reduction in the mean forced expiratory flow during the middle half of the forced vital capacity appeared to be an early sensitive index for the development of BO. An appreciation of these different modes of presentation and progression of BO is potentially important in the assessment of prognosis and management of the SLT recipient.

Analysis of bronchoalveolar lavage from human lung transplant recipients by flow cytometry

Bronchoalveolar lavage (BAL) cells and peripheral blood leucocytes (PBL) from 24 lung transplant recipients were analysed for leucocyte subsets and expression of cell surface antigens. Total and differential white cell counts were performed on BAL, and lymphocyte subsets were evaluated in both BAL and peripheral blood. Measurement of immunofluorescence by flow cytometry was used to assess the percentage of: T cells (CD3+); T-helper cells (CD4+); T-cytotoxic/suppressor cells (CD8+); and activated lymphocytes (HLA-DR+). Lymphocyte subsets in BAL demonstrated marked differences to those in blood. A lower percentage of CD3+ and CD4+ lymphocytes were found in BAL, whereas CD8+ cells were more prevalent in BAL than in PBL. The mean CD4:CD8 ratio was significantly lower in BAL (1:1) than in blood (2.1:1). In the absence of pulmonary infection, there was a trend for a lower CD4:CD8 ratio in BAL associated with acute rejection (1.1:1) and obliterative bronchiolitis (1:1), when compared to the group with no evidence of rejection (1.4:1). In the absence of pulmonary rejection, pulmonary infection was associated with a marginally lower CD4:CD8 ratio in BAL (0.7:1), than when infection was absent (1.4:1). This difference was more evident in cases of cytomegalovirus (CMV) infection with a mean CD4:CD8 ratio of 0.3:1, compared to 1.5:1 in the absence of CMV disease (P < 0.05).

Transplantation immunology

A major function of the immune response is the discrimination of self from nonself. It is this response that must be overcome in transplant rejection. Progress in understanding these basic immune mechanisms has helped to improve clinical outcome and lays the foundation for a new generation of therapies.

Bronchiolitis obliterans organizing pneumonia associated with massive L-tryptophan ingestion

A 51-year-old woman developed acute febrile illness with respiratory failure following intake of L-tryptophan. An open lung biopsy specimen established the histopathologic nature of the lung lesion as bronchiolitis obliterans organizing pneumonia (BOOP). There was no evidence of other known causes usually associated with BOOP. Her condition improved with corticosteroid therapy. The entity of BOOP now should be added to the growing list of illnesses associated with the use of L-tryptophan.

Management of lung transplant rejection

Using current immunosuppressive protocols, rejection is common after lung transplantation. Most recipients have at least one episode of acute rejection, and approximately 25 percent of recent long-term survivors have developed chronic rejection. Acute rejection has usually been reversible with treatment, but chronic rejection has responded poorly, relapsed frequently, and been one of the leading causes of late morbidity and mortality. Appropriate management of rejection is predicated on timely, accurate diagnosis. Clinical criteria for the diagnosis of acute rejection are useful but nonspecific, and TBB has emerged as the procedure of choice for diagnosing acute rejection and infection. Chronic rejection is manifested by OB and is characterized physiologically by the development of airflow obstruction. Although histologic confirmation is preferable, the sensitivity of TBB for the detection of OB has been inconsistent, and the specificity has been low. Lung transplantation has indeed come of age, but understanding the immunopathogenesis and improving the clinical management of rejection remain major challenges for the next decade.

Serum neopterin after lung transplantation

OBJECTIVE

Neopterin (N), a marker for activated cell-mediated immunity, was assayed in the sera of 44 lung recipients early and late after transplantation. The study was a prospective, blind clinical trial designed to evaluate the following: (1) the daily dynamics of the serum neopterin/creatinine (N/C) ratio during the first 3 weeks after transplantation; (2) the correlation between changes in the serum N/C ratio and episodes of rejection or infection; (3) the correlation between the serum N/C ratio and the concentration of serum soluble interleukin 2 receptor (sIL-2R), a marker of T-cell activation; and (4) the potential value of monitoring the serum N/C ratio during noninvasive long-term follow-up of lung recipients.

METHODS

Sera from lung recipients were collected every day or every 2 days for the first 3 weeks after transplantation (22 patients) and before fiberoptic bronchoscopy and routine consultation (44 patients). The N concentrations were determined by radioimmunoassay and sIL-2R levels were measured using a sandwich enzyme immunoassay.

RESULTS

Serum N/C is an early and sensitive marker of immune activation in the 21 days following transplantation. The N/C ratios during early rejections (815 +/- 182 mumol/mol) and infections (677 +/- 75 mumol/mol) were higher than those in patients with no complications (160 +/- 32 mumol/mol). In contrast, the N/C ratio did not increase during rejection later after transplantation. More than 3 weeks after transplantation, an increase in the N/C ratio was specifically correlated with infections, mainly those due to cytomegalovirus (CMV) (control subjects, 132 +/- 12 mumol/mol; rejections, 163 +/- 25 mumol/mol; CMV pneumonia, 786 +/- 103 mumol/mol, p < 0.001). The N/C ratio correlated with sIL-2R serum levels (r = 0.625, p < 0.001).

CONCLUSIONS

Our results indicate that more than 3 weeks after transplantation, the serum N/C ratio increases only in cases of infection, mostly CMV pneumonia. In contrast, both rejection and infectious complications are associated with an increased N production in the early postoperative period.

Selection of patients for lung transplantation

The number of lung and heart-lung transplantations is growing rapidly, and hundreds of combined heart-lung, single-lung, and double-lung transplantations have been performed to date, resulting in increased survival and improved quality of life for patients with end-stage pulmonary disorders. Improved surgical technique, immunosuppression, and optimal patient selection are largely responsible for this success. Although the indications for transplantation continue to expand, the number of potential recipients far exceeds the number of available donors, making the evaluation and selection process vital to the success of any transplantation program. A multidisciplinary approach is presented that can be expected to eliminate a large number of prospective candidates and thus enhance matching limited donor organs with transplantation candidates.

Critical care management of lung transplant recipients

In the last 10 years, lung transplantation has become an increasingly common procedure for patients with end-stage respiratory disease. Although long-term survival can be achieved, there is still significant morbidity within the first year. Early postoperative problems that may be anticipated include respiratory insufficiency, airway anastomotic problems, hemorrhage, infection, and episodes of acute rejection. These problems and others make the immediate perioperative period particularly challenging. With aggressive management, however, the probability of a successful outcome can be enhanced.