THE ROLE OF CARDIOPULMONARY EXERCISE TESTING IN LUNG AND HEART-LUNG TRANSPLANTATION

Health-related Quality-of-Life Determinants in Lung Transplantation

BACKGROUND

In light of recent reviews, we examined the effect of individual and clinical factors, associated with lung transplantation (LTx), on health-related quality of life (HRQL).

METHODS

HRQL was measured cross-sectionally on 34 candidates and 71 lung transplant recipients, using the Short Form 36-item questionnaire (SF-36), of the Medical Outcomes Study. Multivariate analysis was used to model each of the 8 SF-36 health domains as a function of individual determinants associated with LTx. The original model included: transplant status; age; gender; time since LTx; forced expiratory volume in 1 second (% predicted); type of LTx received; lung disease; whether within 1 month of the interview the participant was hospitalized; days in hospital (LOS); and whether infection or rejection occurred. Final models were chosen using a statistical cutoff of alpha < or = 0.10 to remain in the model.

RESULTS

After adjusting for important predictors, lung transplantation was positively associated with all domains (p < 0.005). Although time since transplantation negatively influenced the physical- and social-related domains (p < 0.05), the effect was small. Clinically meaningful effects on physical HRQL domains were observed with disease (p < 0.01), type of transplant received (p < 0.05) and hospital stay (p < 0.05). Gender played a role in mental health (p < 0.05).

CONCLUSIONS

Clinical events leading to hospitalization limit some HRQL domains. Different factors influence the physical, social and mental health domains, and thus future studies should focus on domain-specific variables to optimize HRQL. The HRQL benefit conferred from LTx renders it a worthwhile option for end-stage lung disease patients with important physical limitations.

Physical functional outcomes after cardiothoracic transplantation

The study of patient healthcare outcomes after cardiothoracic transplantation has increased substantially over the last 2 decades. Physical function after heart, lung, and heart-lung transplantation has been studied using both subjective and objective measures. The majority of reports in the literature on physical function after cardiothoracic transplantation are descriptive and observational. The purposes of the article are to review and critique the existing literature on cardiothoracic recipients' subjective and objective physical function, including respiratory function for heart-lung and lung transplant recipients. In addition, the literature on sexual function in cardiothoracic recipients is examined, the gaps in the literature are identified, and recommendations are given for future research.

Clinical exercise testing

Clinical exercise testing is increasingly being utilized in clinical practice because of the valuable, often unique information that it provides in patient diagnosis and management. This is also due to a growing awareness that resting cardiopulmonary measurements provide an unreliable estimate of functional capacity. A continuum of exercise testing modalities for functional evaluation from "low tech" to "high tech" will be discussed. These include the six minute walk test, shuttle walk test, exercise induced bronchoconstriction test, cardiac stress test, and cardiopulmonary exercise testing. The main focus of this article will be cardiopulmonary exercise testing including indications, important measurements, salient methodological considerations, and interpretation.

Lung transplantation for primary pulmonary hypertension

Recent progress in medical therapies has diminished the role of transplantation in the management of PPH during the past decade. Drug therapy is not effective in some patients, responses to therapy are not sustained over time in others, and drug side effects eventually limit the benefits of treatment in a few more. Lung transplantation therefore ultimately is the only alternative for patients whose PPH is severe and cannot be managed medically. Choosing the right patient as a transplant candidate and the right time to make the initial referral to a transplant center are the crucial initial steps in the transplantation process, and the long waiting time before transplantation must be integrated into this decision. The outcome of lung and heart-lung transplantation for PHH has been good but sobering. Functional recovery has been excellent, but long-term survival results have been limited by the high prevalence of chronic allograft rejection.

Care before and after lung transplant and quality of life research

Lung transplantation is a growing surgical option for patients with end-stage lung and pulmonary vascular diseases. After completing an extensive evaluation and meeting the selection criteria, patients are listed for either single or bilateral-sequential lung transplantation. Immediate postoperative management requires detailed attention to fluid management, monitoring for infection, reperfusion injury, pulmonary hygiene, and pain management. Length of stay depends on the patient's condition before transplant and postoperative complications. Discharge from the hospital can be as early as 7 days after transplantation. Newer immunosuppressive medications offer more options for treating and preventing rejection. Advanced practice nurses, such as coordinators, case managers, nurse practitioners, and clinical nurse specialists, are uniquely positioned to play key roles in coordinating the care of transplant patients across settings and both before and after the transplant procedure. The perioperative needs of lung transplant patients and the impact of this complex procedure on the recipients' and family's quality of life merit further investigation by clinicians and researchers.

Lung transplantation at the turn of the century

Lung transplantation has become a viable treatment option for patients with end-stage lung disease. Donor selection and organ allocation must follow specific guidelines. Single, bilateral, and living-donor lobar transplantation have all been performed successfully for a variety of diseases. Complications include reimplantation response and airway complications. Rejection may occur in the hyperacute, acute, or chronic settings and requires judicious management with immunosuppression. Infection and malignancy remain potential complications of the commitment to lifelong systemic immunosuppression. Survival statistics have remained encouraging and continue to improve with experience. Improved exercise tolerance and quality of life have been demonstrated in the years following transplantation. Remaining obstacles include limited donor organ availability, long-term graft function, and patient survival. However, ongoing advances in immune tolerance and standardized training of physicians in the care of transplant patients should carry lung transplant forward in the twenty-first century.

Symptom experiences of lung transplant recipients: comparisons across gender, pretransplantation diagnosis, and type of transplantation

PURPOSES

To investigate symptom experiences of patients who have single and bilateral-sequential lung transplantation and to determine whether differences exist according to gender, pretransplantation diagnosis, and type of transplantation procedure.

DESIGN AND METHODS

In the context of a descriptive, comparative survey design, surviving recipients of single and bilateral-sequential lung transplants (n = 56) were mailed a symptom frequency and distress questionnaire. The response rate was 85.7% (n = 48). The average time since the recipients' lung transplantations was 1.5 +/- 0.7 years.

RESULTS

Recipients of lung transplants reported that several symptoms (eg, muscle weakness, shortness of breath with activity, and changed appearance) were both frequently occurring and quite distressing. Other symptoms were identified as being distressing, but not frequently occurring, or vice versa. Significant (P <.05) differences were found for symptom experiences among pretransplant diagnostic groups and between genders and types of transplant procedures.

CONCLUSIONS

These findings elucidate the symptom experiences of recipients of lung transplants and suggest that subgroup differences exist. The data provide a basis for strengthening patient and family education and for developing symptom management strategies. Further investigation of the symptom experiences of the recipients of lung transplants is needed, especially in relation to subgroups.

Respiratory and limb muscle function in lung allograft recipients

Lung transplantation recipients have reduced exercise capacity despite normal resting pulmonary and hemodynamic function. The limiting factor may be contractile dysfunction of skeletal muscle. To test this postulate, we measured limb and respiratory muscle function in nine clinically stable lung allograft recipients (six men and three women, aged 30 to 65 yr, at 5 to 102 mo after transplantation) with reduced exercise capacity. Respiratory muscle strength was tested by measuring maximal inspiratory and expiratory pressure (MIP and MEP, respectively). Ankle dorsiflexor muscle strength was measured during maximal voluntary contraction (MVC). In a subset of six recipients, we also measured contractile properties and fatigue characteristics of the tibialis anterior muscle, using electrical stimulation of the motor point. Data were compared with values from age- and sex-matched control subjects. MIP values of transplant recipients did not differ from control values; however, MEP was blunted by 30% relative to control (p < 0.05), and MVC was decreased by 39% (p < 0.05). The force-frequency relationships and fatigue characteristics of the tibialis anterior were not different between the patient and control groups. We conclude that stable lung allograft recipients experience expiratory and lower limb weakness that may contribute to exercise intolerance.

Surgical treatment of chronic obstructive pulmonary disease

Over the past several decades, a number of surgical techniques have been developed for the treatment of chronic obstructive pulmonary disease. Many of these procedures have been abandoned because of lack of efficacy and/or high morbidity and mortality. At the present time, lung transplantation, reduction pneumoplasty for giant bullous emphysema, and lung volume reduction surgery are being performed in a number of centers. Data concerning the effectiveness of these procedures is accumulating and will ultimately need careful analysis to determine long-term outcomes in this group of patients.

Cardiopulmonary exercise testing before and after lung and heart-lung transplantation

Heart-lung (HLT) and lung transplantation (LT) have been shown to be effective procedures for patients with end-stage cardiopulmonary disorders. As yet, few data exist on the exercise performance of patients before and after thoracic transplantation except with regard to 6-min walk tests. In this article we report cardiopulmonary exercise test results of lung and heart-lung transplant recipients in comparison with their pretransplant values. We studied 103 consecutive recipients of single-lung (n = 46), bilateral lung (n = 32), and heart-lung (n = 25) transplants. Cardiopulmonary exercise testing with a cycle ergometer was performed before and shortly after surgery. Before transplantation, all patients showed severe exercise intolerance and markedly impaired parameters reflecting cardiopulmonary function (e.g., work capacity: 20 +/- 11% predicted; oxygen uptake: 34 +/- 12% predicted; oxygen pulse: 50 +/- 18% predicted; functional dead space ventilation: 57 +/- 10% of minute ventilation; alveolar-arterial oxygen difference during exercise: 79 +/- 15 mm Hg). At 55 +/- 9 d after transplantation, transplant recipients reached maximum oxygen uptakes in the range of 22 to 71% of predicted values; the peak oxygen uptake was increased after transplantation (13.1 +/- 3.4 ml/min/kg versus 10.4 +/- 3.8 ml/min/kg; p < 0.001). Work capacity, oxygen pulse, tidal volume, and peak minute ventilation did not differ in patients following single- or double-lung tranplantation or HLT. Ventilatory factors did not appear to limit exercise capacity in any group. Despite the persistent limitations in aerobic capacity and work rate seen in many of the recipients, cardiopulmonary performance is reasonably well restored shortly after LT and HLT.

Lung Transplantation for COPD

In appropriately selected patients with COPD and alpha1-antitrypsin deficiency emphysema, lung transplantation prolongs life, improves functional capacity, and enhances quality of life. However, rejection remains an obstacle to better medium-term results, and lung transplantation is a treatment, not a cure and not a panacea.

Aerobic endurance training program improves exercise performance in lung transplant recipients

STUDY OBJECTIVE

To determine whether an aerobic endurance training program (AET) in comparison to normal daily activities improves exercise capacity in lung transplant recipients.

PATIENTS AND STUDY DESIGN

Nine lung transplant recipients (12+/-6 months after transplant) were examined. All patients underwent incremental bicycle ergometry with the work rate increased in increments of 20 W every 3 min. Identical exercise tests were performed after 11+/-5 weeks of normal daily activities and then after a 6-week AET. The weekly aerobic training time increased from 60 min at the beginning to 120 min during the last week. Training intensity ranged from 30 to 60% of the maximum heart rate reserve.

RESULTS

Normal daily activities had no effect on exercise performance. The AET induced a significant decrease in resting minute ventilation from 14+/-5 to 11+/-3 L/min. At an identical, submaximal level of exercise, a significant decrease in minute ventilation from 47+/-14 L/min to 39+/-13 L/min and heart rate from 144+/-12 to 133+/-17 beats/min, before and after the AET, was noted. The increase in peak oxygen uptake after AET was statistically significant (1.13+/-0.32 to 1.26+/-0.27 L/min).

CONCLUSIONS

These data demonstrate that normal daily activities do not affect exercise performance in lung transplant recipients > or = 6 months after lung transplantation. An AET improves submaximal and peak exercise performance significantly.

Cystic fibrosis: bilateral living lobar versus cadaveric lung transplantation

Living donor transplantation is now an acceptable option that should be considered for selected cystic fibrosis patients with end-stage lung disease. Two lungs obtained from live donors can adequately support an adult cystic fibrosis patient. The morbidity from lobectomy to the healthy donor is minimal.

Lung transplantation for alpha 1-antitrypsin deficiency emphysema

Lung transplantation is an option for appropriately selected patients with end-stage emphysema caused by alpha 1-antitrypsin deficiency. The functional results have been excellent after single or bilateral lung transplantation, and the medium-term survival results have been good. However, the role of alpha 1-antitrypsin replacement therapy after lung transplantation remains uncertain, and further investigation is needed.

Clinical applications of cardiopulmonary exercise testing

Noninvasive measurement of metabolic and cardiorespiratory variables can be readily obtained using computerized systems as part of exercise testing of patients on a cycle ergometer or treadmill. The major indications for CPEX are: to assess exercise-related symptoms, especially dyspnea and chest pain; to measure exercise capacity including acceptability of patients with end-stage heart disease for cardiac transplantation; to evaluate for impairment/disability; to establish safety and guidelines for exercise training; and to assess response to specific therapy. As most patients with chronic cardiorespiratory disorders reduce their activities and consequently become deconditioned, CPEX should be considered as part of the initial evaluation. The results of CPEX should enable the physician to understand the reason(s) for the patient's exercise limitation and usually support the recommendation that the patient participate in a reconditioning or rehabilitation program. Should expired gases be measured as routine for all exercise tests? The use of CPEX depends on the clinical question. If the question is, "Does the patient have ischemic heart disease?", then a standard "cardiac stress test" is adequate. If the clinical question is, "Why is the individual limited in exercise ability?" or "Why is a patient breathless with activities?", then comprehensive CPEX is indicated. One important issue relating to CPEX is cost effectiveness. Do the results of CPEX justify the expense? There are little if any data to answer this question. However, if CPEX can establish a specific diagnosis, exclude significant heart disease, estimate work capacity, and/or provide guidelines for prescription of exercise intensity, this information may be invaluable to the individual patient and to the health-care provider. It is possible that CPEX may answer a specific clinical question and thereby actually eliminate the need and reduce the cost of additional expensive diagnostic tests. A prospective assessment of the cost effectiveness of CPEX will be important for select clinical problems.

Lung transplantation in chronic airflow limitation

Lung transplantation is an option for appropriately selected patients with end-stage chronic airflow limitation. The functional results have been excellent after single or bilateral lung transplantation, and the medium-term survival results have been good. Obliterative bronchiolitis, however, thought to be a manifestation of chronic rejection, occurs in approximately 40% of recipients, and it is the major cause of late morbidity and mortality in lung transplant recipients.

Comparison of early functional results after volume reduction or lung transplantation for chronic obstructive pulmonary disease

BACKGROUND

Bilateral lung volume reduction is designed to improve pulmonary function in selected patients with severe emphysema by improving diaphragmatic and chest wall mechanics. Early results of lung volume reduction suggest significant improvement to selected patients with chronic obstructive pulmonary disease, some of whom might otherwise be considered for lung transplantation. The purpose of this review was to compare intermediate results of volume reduction with single and bilateral lung transplantation.

METHODS

Functional performance and survival after volume reduction were compared with single and bilateral sequential lung transplantation. After evaluation, patients were enrolled in a supervised intensive preoperative and postoperative program of pulmonary rehabilitation. Functional assessment, including pulmonary function tests, room air arterial blood gas analysis, and 6-minute walk distance, was obtained before the operation and 3, 6, and 12 months after the operation.

RESULTS

Thirty-three patients underwent volume reduction (mean age 57 years), 39 patients single lung transplantation (55 years), and 27 patients bilateral lung transplantation (49 years). Early mortality was 0, 1 of 39, and 2 of 25 and mortality at 12 months was 1 of 33, 4 of 39, and 4 of 25 in the volume reduction, single, and bilateral lung transplantation groups, respectively. At 6 months, mean forced expiratory volume in 1 second was improved by 79% (volume reduction), by 231% (single lung transplantation), and by 498% (bilateral lung transplantation) over preoperative values. Exercise endurance as measured by 6-minute walk distance increased by 28% (volume reduction), by 47% (single lung transplantation), and by 79% (bilateral lung transplantation) from baseline. At 6 months, all patients having single or bilateral lung transplantation and 26 of 33 patients having volume replacement were free of supplemental oxygen.

CONCLUSIONS

Although single and bilateral lung transplantation result in superior lung function, volume reduction achieves satisfactory improvement of disabling symptoms early after operation while avoiding immunosuppression and transplant-specific complications. Our experience suggests that (1) volume reduction is a suitable alternative in selected patients eligible for transplantation; (2) volume reduction provides an earlier option for treatment in patients who may require transplantation at some future date; (3) volume reduction is the only surgical treatment available to the many patients who are not current or future transplant candidates. Conversely, in patients not suitable for volume reduction, transplantation remains the only choice for surgical therapy.