Relationship between impaired pulmonary diffusion and cardiopulmonary exercise capacity after heart transplantation

Reference Values for Pulmonary Single-Breath Diffusing Capacity - Results of the "Study of Health in Pomerania"

OBJECTIVES

 The assessment of pulmonary single-breath diffusing capacity is a frequently performed diagnostic procedure and considered as an important tool in medical surveillance examinations of pulmonary diseases.The aim of this study was to establish reference equations for pulmonary single-breath diffusing capacity parameters in a representative adult-population across a wide age range and to compare the normative values from this sample with previous ones.

METHODS

 Diffusing capacity measurement was carried out in 3566 participants (1811 males) of a cross-sectional, population-based survey ("Study of Health in Pomerania - SHIP").

RESULTS

 Individuals with cardiopulmonary disorders and current smoking habits were excluded, resulting in 1786 healthy individuals (923 males), aged 20 - 84 years. Prediction equations for both sexes were established by quantile regression analyses, taking into consideration the influence of age, height, weight and former smoking.

CONCLUSION

 The study provides a novel set of prediction equations for pulmonary single-breath diffusing capacity in an adult Caucasian population. The results are comparable to previously reported equations, underline their importance and draw attention to the need for up-to-date reference equations that adequately take into account both the subjects' origin, age, anthropometric characteristics and the equipment used.

Importance of physical capacity and the effects of exercise in heart transplant recipients

One of the most important prognostic factors in heart failure patients is physical capacity. Patients with very poor physical performance and otherwise eligible, may be listed as candidates for heart transplantation (HTx). After such surgery, life-long immunosuppression therapy is needed to prevent rejection of the new heart. The dark side of immunosuppression is the increased risk of infections, kidney failure, cancer and advanced atherosclerosis (cardiac allograft vasculopathy), with the two latter conditions as the main causes of later mortality. In a worldwide perspective, 50% of the HTx patients survive past 10 years. Poor aerobic capacity prior to graft deterioration is not only limited to the failing heart, but also caused by peripheral factors, such as limited function in the skeletal muscles and in the blood vessels walls. Exercise rehabilitation after HTx is of major importance in order to improve physical capacity and prognosis. Effects of high-intensity interval training (HIT) in HTx recipients is a growing field of research attracting worldwide focus and interest. Accumulating evidence has shown that HIT is safe and efficient in maintenance HTx recipients; with superior effects on physical capacity compared to conventional moderate exercise. This article generates further evidence to the field by summarizing results from a decade of research performed at our center supported by a broad, but not strict formal, literature review. In short, this article demonstrates a strong association between physical capacity measured after HTx and long-term survival. It describes the possible “HIT-effect” with increased levels of inflammatory mediators of angiogenesis. It also describes long-term effects of HIT; showing a positive effect in development of anxiety symptoms despite that the improved physical capacity was not sustained, due to downregulation of exercise and intensity. Finally, our results are linked to the ongoing HITTS study, which investigates safety and efficiency of HIT in de novo HTx recipients. Together with previous results, this study may have the potential to change existing guidelines and contribute to a better prognosis for the HTx population as a whole.

Noninfectious Pulmonary Complications of Liver, Heart, and Kidney Transplantation: An Update

Despite significant advances in surgical techniques, perioperative care, and immunosuppressive therapy, solid organ transplantation still carries considerable risk of complications. Pulmonary complications, in particular, are a major cause of morbidity and mortality. Although infectious complications prevail, the lungs are also vulnerable to a variety of noninfectious complications related to the transplant surgery and adverse effects of the immunosuppressive regimen. This article focuses on noninfectious pulmonary complications associated with the 3 most commonly performed solid organ transplant procedures: liver, kidney, and heart.

Exercise limitation following transplantation

Organ transplantation is one of the medical miracles or the 20th century. It has the capacity to substantially improve exercise performance and quality of life in patients who are severely limited with chronic organ failure. We focus on the most commonly performed solid-organ transplants and describe peak exercise performance following recovery from transplantation. Across all of the common transplants, evaluated significant reduction in VO2peak is seen (typically renal and liver 65%-80% with heart and/or lung 50%-60% of predicted). Those with the lowest VO2peak pretransplant have the lowest VO2peak posttransplant. Overall very few patients have a VO2peak in the normal range. Investigation of the cause of the reduction of VO2peak has identified many factors pre- and posttransplant that may contribute. These include organ-specific factors in the otherwise well-functioning allograft (e.g., chronotropic incompetence in heart transplantation) as well as allograft dysfunction itself (e.g., chronic lung allograft dysfunction). However, looking across all transplants, a pattern emerges. A low muscle mass with qualitative change in large exercising skeletal muscle groups is seen pretransplant. Many factor posttransplant aggravate these changes or prevent them recovering, especially calcineurin antagonist drugs which are key immunosuppressing agents. This results in the reduction of VO2peak despite restoration of near normal function of the initially failing organ system. As such organ transplantation has provided an experiment of nature that has focused our attention on an important confounder of chronic organ failure-skeletal muscle dysfunction.

Weight gain in long-term survivors of kidney or liver transplantation--another paradigm of sarcopenic obesity?

OBJECTIVE

Obesity in transplant recipients is a frequent phenomenon but data from body composition analyses in long-term survivors are limited. Body composition and energy metabolism were studied in patients after liver (LTX) and kidney (KTX) transplantation and patients with liver cirrhosis (LCI) or on chronic hemodialysis (HD) and compared to healthy controls.

METHODS

In 42 patients 50.0 mo (median; range 17.1-100.6) after LTX and 30 patients 93.0 mo (31.2-180.1) after KTX as wells as in LCI (n = 39) or HD (n = 10) patients mid-arm muscle and fat area, body cell mass, and phase angle (bioimpedance analysis), and resting energy expenditure (indirect calorimetry, REE(CALO)) were measured.

RESULTS

Obesity was more prevalent in LTX (17%) than LCI (3%) and in KTX (27%) than in HD (10%). In LTX and KTX, phase angle was higher than in end-stage disease (LTX 5.6° [4.1-7.2] versus LCI 4.4° [2.9-7.3], P < 0.001; KTX 5.9° [4.4-8.7] versus HD 4.3° [2.9-6.8]) but was lower in all patient groups than in controls (7.1°; 4.6-8.9; P < 0.001). In LCI and HD REE(CALO) was higher than predicted, while in LTX and KTX REE(CALO) was not different from predicted REE.

CONCLUSIONS

Despite excellent graft function, many long-term LTX or KTX survivors exhibit a phenotype of sarcopenic obesity with increased fat but low muscle mass. This abnormal body composition is observed despite normalization of the hypermetabolism found in chronic disease and cannot be explained by overeating. The role of appropriate nutrition and physiotherapy after transplantation merits further investigation.

Exercise performance increases coincident to body weight over the first two years following cardiac transplantation

BACKGROUND

To determine whether exercise performance changed over time once patients stabilized after heart transplantation, metabolic stress testing was performed in patients one and two yr post-heart transplantation.

METHODS

The patient cohort includes those transplanted in our program who survived at least two yr and were able to perform metabolic stress tests during their one- and two-yr annual evaluations. Standard stress test parameters were assessed, including weight, body surface area, rest and exercise heart rate (HR) and blood pressure (BP), exercise time, anaerobic threshold (AT), and maximum VO2 (MVO2). Ejection fraction by echo was also collected. Each patient served as their own control and data were compared using paired t-testing.

RESULTS

Fifty patients were included in the cohort, 48 of whom were able to exercise to at least AT. Patient weight increased from year 1 to year 2 (82.4 ± 15.1 vs. 85.0 ± 17.0 kg, p = 0.035). Systolic BP increased approximately 40 mmHg with exercise with no change in diastolic BP, and there was no difference between years 1 and 2. HR increased approximately 25 bpm with exercise. There was no difference in resting HR but exercise HR increased significantly between yrs (148 ± 15 bpm vs. 154 ± 18 bpm, p = 0.017). Both VO2 at AT and MVO2 increased significantly from year 1 to year 2 (1116 ± 347 mL/min vs. 1192 ± 313 mL/min, p = 0.049 and 1523 ± 337 mL/min vs. 1599 ± 356 mL/min, p = 0.012, respectively) but when corrected for body weight, there were no differences (VO2-AT 13.6 ± 4.0 mL/kg/min vs. 14.0 ± 4.0 mL/kg/min; MVO2 18.7 ± 4.2 mL/kg/min vs. 18.8 ± 4.1 mL/kg/min). All other measured parameters were not different. There was a weak but statistically significant correlation between change in peak HR and change in VO2 at AT between one and two yr post-transplantation (r = 0.30, p = 0.04).

CONCLUSIONS

We conclude that exercise performance as measured by VO2 can increase over time post-heart transplantation and in our cohort appears to be related to both an increase in body weight and an increase in HR from years 1 and 2.

Noninfectious Pulmonary Complications of Liver, Heart, and Kidney Transplantation

Because of their chronically immunosuppressed status, solid organ transplant recipients are continually at risk for infectious pulmonary complications. In addition, however, a number of noninfectious pulmonary complications plague the transplant recipient. These complications arise because of numerous factors, including the underlying conditions that preceded transplantation, the transplant surgery itself, and toxicity of post-transplantation medications. This article focuses on noninfectious pulmonary complications in the three largest recipient populations: liver, kidney, and heart.

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.

Adherence to the Therapeutic Regimen in Heart, Lung, and Heart-Lung Transplant Recipients

Optimal outcome after heart, lung, and heart-lung transplantation can only be obtained if patients are supported in adhering to a lifelong therapeutic regimen. The transplant patient's therapeutic regimen consists of a lifelong medication regimen, including immunosuppressive drugs; monitoring for signs and symptoms related to complications; avoidance of risk factors for cardiovascular disease and cancer (ie, diet and exercise prescriptions, nonsmoking); avoidance of abuse/dependence of alcohol or illegal drugs, as well as attending regular clinical checkups. Nonadherence to all aspects of this regimen is substantial. Nonadherence has been related to negative clinical outcome in view of acute rejections, graft vasculopathy, higher costs, and mortality. This review focuses on the prevalence, correlates, and consequences of nonadherence to the therapeutic regimen in heart, lung, and heart-lung transplantation. The current state of the-art on adherence-enhancing interventions is reported. Priorities for future research are outlined.

Exercise after heart transplantation

Exercise intolerance in heart transplant recipients (HTR) has a multifactorial origin, involving complex interactions among cardiac, neurohormonal, vascular, skeletal muscle and pulmonary abnormalities. However, the role of these abnormalities may differ as a function of time after transplantation and of many other variables. The present review is aimed at evaluating the role of cardiac, pulmonary and muscular factors in limiting maximal aerobic performance of HTR, and the benefits of chronic exercise. Whereas pulmonary function does not seem to affect gas exchange until a critical value of diffusing lung capacity is attained, cardiac and skeletal muscle function deterioration may represent relevant factors limiting maximal and submaximal aerobic performance. Cardiac function is mainly limited by chronotropic incompetence and diastolic dysfunction, whereas muscle activity seems to be limited by impaired oxygen supply as a consequence of the reduced capillary network. The latter may be due to either immunosuppressive regimen or deconditioning. Endurance and strength training may greatly improve muscle function and maximal aerobic performance of HTR, and may also reduce side effects of immunosuppressive therapy and control risk factors for cardiac allograft vasculopathy. For the above reasons exercise should be considered an important therapeutic tool in the long-term treatment of heart transplant recipients.

Abnormalities of pulmonary diffusion capacity in long-term survivors after kidney transplantation

STUDY OBJECTIVES

Alterations in pulmonary function and interstitial changes in the lungs of renal transplant recipients have been described, but prospective longitudinal data are lacking.

DESIGN

A prospective analysis of pulmonary function tests and pulmonary CT in renal transplant recipients in stable condition at two different time points following kidney transplantation (KT).

PATIENTS

Seventy-nine renal transplant recipients in stable condition were included. The first studies were performed 83 months (median) following KT. In 36 of these patients, it was possible to obtain a second set of studies after an additional follow-up period of 22 months.

RESULTS

Approximately 11% of all patients showed significant restrictive and obstructive abnormalities in pulmonary function tests. In the majority of transplant recipients, considerable defects in pulmonary diffusion capacity were documented: lung transfer factor for carbon monoxide, or transfer coefficient for carbon monoxide were < 80% of the predicted value in 57% and 76%, respectively. In 24% of the CT studies, substantial interstitial alterations were found. However, no significant correlations could be established between CT morphology and the presence of diffusion abnormalities. At the time of the second follow-up investigation, we found a further decrease in diffusion capacity in approximately 30% of patients despite an unchanged CT morphology in most of these patients.

CONCLUSION

We conclude that an impairment of pulmonary diffusion capacity exists in the majority of long-term survivors after KT. In our opinion, CT-detectable interstitial findings do not represent a causative factor for these abnormalities. A plausible hypothesis is a "low-grade pulmonary microvascular injury" in combination with a long-term decrease in pulmonary perfusion. The impact of these diffusion defects on symptomatology and prognosis in kidney transplant recipients is largely unclear, and further studies are needed.

Single-breath carbon monoxide diffusing capacity

Measurement of DL(CO) remains a clinically useful way to assess transfer of gases across the lung. It is important, however, to be vigilant in controlling the sources of variation and to be aware of those that remain when interpreting the measured values.