| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Guest Access | Sign In via User Name/Password
|
|
|
|||||||
Guest Access | Sign In via User Name/Password |
|||||||||
Rochester, MN
Dr. Afessa is Associate Professor of Medicine, Division of Pulmonary and Critical Care Medicine, Mayo Clinic College of Medicine.
Correspondence to: Bekele Afessa, MD, FCCP, 200 First St SW, Mayo Clinic, Rochester, MN 55905; e-mail: Afessa.Bekele{at}mayo.edu
Thousands of patients undergo blood and marrow transplantation (BMT) each year, mainly for malignant hematologic disorders.12 Their underlying diseases, intensive chemotherapy, radiation therapy, and conditioning regimen, with or without total body irradiation, are among the factors that place BMT recipients at high risk for posttransplant pulmonary complications. The development of graft-vs-host disease (GVHD) and the frequent use of immunosuppressant therapy increase this risk to an even higher level in allogeneic BMT recipients.3 As a result, pulmonary complications develop in 30 to 60% of BMT recipients.456 With the recent developments and wide use of effective prophylaxis against certain infections, the spectrum of pulmonary complications is changing.78 The pretransplant pulmonary evaluation should focus on identifying and modifying the factors that increase the risk for posttransplant complications.
Although epidemiologic studies have identified potential risk factors, it is not easy to predict accurately which BMT recipients will have pulmonary and other complications. Recognition of the prognostic factors that accurately predict the development of serious complications following transplant are important for both health-care providers and patients to make informed decisions based on the balance between the risks and benefits. Cardiopulmonary assessment has become a routine part of pre-BMT evaluation. However, there are scarce data addressing the clinical utility of such an assessment.9 Although conflicting results have been published, most studies91011121314 show no correlation between pretransplant cardiac findings and posttransplant complications. In contrast, many publications91516171819 suggest correlation between pretransplant pulmonary abnormalities and posttransplant complications.
In this issue of CHEST (see page 145), White et al describe the pretransplant respiratory and skeletal muscle strength and submaximal exercise capacity of 56 allogeneic BMT recipients. In their institution, Tufts-New England Medical Center, pretransplant measurement of maximal inspiratory and expiratory pressures and 6-min walk test have become parts of the routine evaluation. This prospective observational study shows that respiratory and skeletal muscle strength, as well as submaximal exercise capacity, are reduced in a significant number of the patients before transplant. However, they were not able to identify risk factors associated with the muscle weakness or reduced exercise capacity, and pre-BMT muscle strength and exercise capacity had no effect on survival.
Previous studies1920 have addressed the role of measuring lung volumes, spirometry, diffusing capacity for carbon monoxide (DLCO), and methacholine challenge during pre-BMT evaluation. Decreased pretransplant expiratory flow, lung volume, and DLCO have been associated with increased risk for posttransplant complications.17192122 However, these findings are not universal, and a small prospective study23 of 43 allogeneic BMT recipients was not able to confirm an association between baseline pulmonary function and subsequent pulmonary complications. In one prospective study,20 the presence of pretransplant airway reactivity measured by methacholine challenge did not correlate with the development of posttransplant pulmonary complications, including bronchiolitis obliterans. Limited data are available with regard to measuring exercise capacity prior to transplant.13
Despite the potential clinical implications, no previous study has addressed the role of respiratory muscle strength in pre-BMT evaluation. White et al should be congratulated for initiating the work on respiratory muscle strength and expanding the available literature on exercise capacity. Muscle weakness and decreased exercise capacity could be related to the underlying disease, nutritional status, metabolic abnormalities, critical illness, anemia, chemotherapy, corticosteroid use, radiation therapy, and GVHD.242526272829 Respiratory and skeletal muscle weakness has the potential to lead to ventilatory insufficiency following transplant and to increase the associated morbidity and mortality. Identification of modifiable risk factors that predispose BMT recipients to muscle weakness has clinical importance. However, White et al were not able to identify such risk factors, probably due to the small size of the study. For the same reason, their study did not have adequate power to assess the impact of muscle weakness on survival. White et al used the "burden of chemotherapy," defined as the number of drugs multiplied by the number of cycles administered, to quantify the amount of chemotherapy patients received. This is an attractive concept, especially for a study with small sample size. However, lumping together all chemotherapeutic agents with qualitatively different effects on muscle strength can obscure the results and lead to wrong conclusions.
Respiratory muscle weakness with diminished vital capacity, and maximal inspiratory and expiratory pressures due to GVHD-associated myositis has been described following allogeneic BMT.830 Knowledge of the pretransplant respiratory muscle strength helps to quantify the extent of the weakness attributable to the posttransplant complication. However, the inclusion of respiratory muscle measurement as a routine part of pretransplant evaluation requires more study. In our institution, we measure pretransplant spirometry and DLCO in all BMT recipients and lung volumes in those with abnormal spirometry or DLCO. We use these measurements to identify patients at risk for posttransplant complications, but pretransplant pulmonary abnormalities should not be used for determining eligibility for BMT. Most of the conditions requiring BMT have no other good treatment alternatives. Moreover, there are no studies defining the pulmonary function criteria for BMT. Although we know that pulmonary function abnormalities can be used to identify BMT recipients at risk for pulmonary complications, the use of these finding for initiating earlier preventative and therapeutic plans needs further investigation.
References
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
