Cardiopulmonary exercise testing after single and double lung transplantation

Cardiac Comorbidity and Exercise Intolerance in Bilateral Lung Transplant Recipients Followed at a Pediatric Center

Reduced exercise capacity is common in young bilateral lung transplantation (Bi-LTx) recipients, but longer-term data on cardiac comorbidities are limited. We evaluate potential cardiac contributions to long-term exercise intolerance in this population. All Bi-LTx recipients at a single pediatric center, who completed routine clinical post-transplant cardiac assessment, including echocardiogram, cardiac exam, and cardiopulmonary exercise testing (CPET), were included. Cardiac risk factors (CRFs) were assessed by history and laboratory tests. CPET-derived peak and percent-predicted peak myocardial oxygen consumption (VO2 peak, ppVO2 peak) were used to quantitate exercise capacity. Percent-predicted peak oxygen pulse (pp peak O2 pulse) assessed stroke volume. 15 patients (67% M; median age 21.6 years, median follow-up from Bi-LTx 7.0 years) were included. Almost all patients (14, 93%) had multiple CRFs; hypertension and hyperlipidemia/dyslipidemia were the most common. On CPET, 93% (n = 14) had abnormal (≤ 85%) ppVO2 peak (median 59%). 73% (n = 11) had abnormal pp peak O2 pulse (median 74%). Ten had blunted heart rate response to exercise. Nine had left ventricular diastolic dysfunction (LV-DD) on echocardiogram. Median percent-predicted forced expiratory volume in one second was 70%. One had severe chronic lung allograft dysfunction. Cardiac risk factors and exercise intolerance are common among young Bi-LTx recipients years post-transplant, even among those without significant pulmonary dysfunction. High prevalence of multiple CRFs, LV-DD, chronotropic dysfunction, and abnormal stroke volume suggest cardiac comorbidities may contribute to intolerance. Medical management of CRFs and tailored exercise may decrease cardiac risk and improve functional capacity for Bi-LTx survivors.

Alterations in Pulmonary Physiology with Lung Transplantation

Lung transplant is a treatment option for patients with end-stage lung diseases; however, survival outcomes continue to be inferior when compared to other solid organs. We review the several anatomic and physiologic changes that result from lung transplantation surgery, and their role in the pathophysiology of common complications encountered by lung recipients. The loss of bronchial circulation into the allograft after transplant surgery results in ischemia-related changes in the bronchial artery territory of the allograft. We discuss the role of bronchopulmonary anastomosis in blood circulation in the allograft posttransplant. We review commonly encountered complications related to loss of bronchial circulation such as allograft airway ischemia, necrosis, anastomotic dehiscence, mucociliary dysfunction, and bronchial stenosis. Loss of dual circulation to the lung also increases the risk of pulmonary infarction with acute pulmonary embolism. The loss of lymphatic drainage during transplant surgery also impairs the management of allograft interstitial fluid, resulting in pulmonary edema and early pleural effusion. We discuss the role of lymphatic drainage in primary graft dysfunction. Besides, we review the association of late posttransplant pleural effusion with complications such as acute rejection. We then review the impact of loss of afferent and efferent innervation from the allograft on control of breathing, as well as lung protective reflexes. We conclude with discussion about pulmonary function testing, allograft monitoring with spirometry, and classification of chronic lung allograft dysfunction phenotypes based on total lung capacity measurements. We also review factors limiting physical exercise capacity after lung transplantation, especially impairment of muscle metabolism. © 2023 American Physiological Society. Compr Physiol 13:4269-4293, 2023.

Diffusing Capacity for Carbon Monoxide (DLCO): Association with long-term outcomes after Lung Transplantation in a 20-year longitudinal study

RATIONALE

The diffusing capacity for carbon monoxide corrected for haemoglobin (DLCO_cor), measures gas movement across the alveolar-capillary interface. We hypothesised that DLCO_cor is a sensitive measure of injurious allograft processes disrupting this interface.

OBJECTIVES

To determine the prognostic significance of the DLCO_cor trajectory on chronic lung allograft dysfunction (CLAD) and survival.

METHODS

A retrospective analysis was conducted of all bilateral lung transplant recipients at a single centre, between Jan-1998 and Jan-2018, with ≥1 DLCO_cor measurements. Low baseline DLCO_cor was defined as the failure to achieve a DLCO_cor >75% predicted. Drops in DLCO_cor were defined as >15% below recent baseline.

RESULTS

1259/1492 lung transplant recipients were included. The median time to peak DLCO_cor was 354 (range 181-737) days and the mean %-predicted DLCO_cor was 80.2% (sd 21.2). Multivariable analysis demonstrated that low baseline DLCO_cor was significantly associated with death (HR 1.68, 95% CI 1.27-2.20, p<0.001). Low baseline DLCO_cor was not independently associated with CLAD after adjustment for low baseline FEV₁ or FVC. Any DLCO_cor declines ≥15% were significantly associated with death, independent of concurrent spirometric decline. Lower %-predicted DLCO_cor values at CLAD onset were associated with shorter post-CLAD survival (HR 0.75 per 10%-unit change, p<0.01).

CONCLUSION

Low baseline DLCO_cor and post-transplant declines in DLCO_cor were significantly associated with survival, independent of spirometric measurements. We propose that DLCO_cor testing may allow identification of a sub-phenotype of baseline and chronic allograft dysfunction not captured by spirometry. There may be benefit in routine monitoring of DLCO_cor after lung transplantation to identify patients at risk of poor outcomes.

Near-normal aerobic capacity in long-term survivors after lung transplantation

The clinical course of lung transplantation (LT) is diverse: some patients present chronic lung allograft dysfunction (CLAD) and progressive decline in pulmonary function, but others maintain normal spirometric values and active lives.

This is a multicentre study reporting, for the first time, near-normal peak V′_O2 values during cardiopulmonary exercise testing and normal exercise capacity in long-term lung transplant recipients without CLADhttps://bit.ly/35ftce3

Respiratory Muscle and Lung Function in Lung Allograft Recipients: Association with Exercise Intolerance

BACKGROUND

In lung transplant recipients (LTRs), restrictive ventilation disorder may be present due to respiratory muscle dysfunction that may reduce exercise capacity. This might be mediated by pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6).

OBJECTIVE

We investigated lung respiratory muscle function as well as circulating pro-inflammatory cytokines and exercise capacity in LTRs.

METHODS

Fifteen LTRs (6 female, age 56 ± 14 years, 63 ± 45 months post-transplantation) and 15 healthy controls matched for age, sex, and body mass index underwent spirometry, measurement of mouth occlusion pressures, diaphragm ultrasound, and recording of twitch transdiaphragmatic (twPdi) and gastric pressures (twPgas) following magnetic stimulation of the phrenic nerves and the lower thoracic nerve roots. Exercise capacity was quantified using the 6-min walking distance (6MWD). Plasma IL-6 and TNF-α were measured using enzyme-linked immunosorbent assays.

RESULTS

Compared with controls, patients had lower values for forced vital capacity (FVC; 81 ± 30 vs.109 ± 18% predicted, p = 0.01), maximum expiratory pressure (100 ± 21 vs.127 ± 17 cm H2O, p = 0.04), diaphragm thickening ratio (2.2 ± 0.4 vs. 3.0 ± 1.1, p = 0.01), and twPdi (10.4 ± 3.5 vs. 17.6 ± 6.7 cm H2O, p = 0.01). In LTRs, elevation of TNF-α was related to lung function (13 ± 3 vs. 11 ± 2 pg/mL in patients with FVC ≤80 vs. >80% predicted; p < 0.05), and lung function (forced expiratory volume after 1 s) was closely associated with diaphragm thickening ratio (r = 0.81; p < 0.01) and 6MWD (r = 0.63; p = 0.02).

CONCLUSION

There is marked restrictive ventilation disorder and respiratory muscle weakness in LTRs, especially inspiratory muscle weakness with diaphragm dysfunction. Lung function impairment relates to elevated levels of circulating TNF-α and diaphragm dysfunction and is associated with exercise intolerance.

Effects of Exercise and Sport in Solid Organ Transplant Recipients: A Review

Solid organ transplantation is the criterion standard treatment for many with end-organ failure and can offer a new independence from the burden of disease. However solid organ transplant recipients (SOTRs) remain at high risk of cardiovascular (CV) disease, and poor quality of life and physical functioning. Increasing physical activity and exercise can improve the health of the general population; however, the effects on those with a transplant remain unclear. Intensive exercise and sporting activity has the potential to be beneficial, although there remain concerns particularly around the effects on immune function and the CV system. This review summarizes what is known about the effects of exercise on determinants of health in SOTRs and then collates the available literature investigating the consequences of intensive exercise and sport on the health of SOTR. There is a paucity of high-quality research, with most evidence being case studies or anecdotal; this is understandable given the relatively few numbers of SOTRs who are performing sport and exercise at a high level. However, if suitable evidence-based guidelines are to be formed and SOTRs are to be given reassurances that their activity levels are not detrimental to their transplanted organ and overall health, then more high-quality studies are required.

Cigarette smoking following lung transplantation: effects on allograft function and recipient functional performance

PURPOSE

Despite mandatory tobacco abstinence following lung transplantation (LTX), some recipients resume smoking cigarettes. The effect of smoking on allograft function, exercise performance, and symptomatology is unknown.

METHODS

A retrospective review was conducted of LTX recipients who received allografts over an 8-year interval and who were subjected to sequential posttransplant pulmonary function testing (PFT), 6-minute walk (6MW) testing, and assessments of exertional dyspnea (Borg score). Using post-LTX PFT results, recipients were determined to have either bronchiolitis obliterans syndrome (BOS), a manifestation of chronic allograft rejection, or normal pulmonary function (non-BOS). With respect to post-LTX pulmonary function, 6MW distances, and Borg scores, comparisons were made between these recipient groups and those who resumed smoking.

RESULTS

Of 34 LTX recipients identified, 13 maintained normal lung function (non-BOS), while 16 demonstrated a decline in their PFT values consistent with BOS. Five recipients began smoking at median postoperative day 365 and smoked 1 pack per day for a mean of 485.6 days. Smokers developed a deterioration of their PFT values that was similar to those with BOS (P = .47) and tended to be worse than those in the non-BOS group (P = .09). All smokers experienced a decline in 6MW distances similar to those with BOS and non-BOS but reported less exertional dyspnea (lower Borg scores) than those with BOS.

CONCLUSION

Recipients of LTX who resume cigarette smoking demonstrate a decline in pulmonary function similar to those afflicted with chronic allograft rejection but do not experience a decrement in their functional performance or increased dyspnea.

The World Transplant Games: an incentive to improve physical fitness and habitual activity in pediatric solid organ transplant recipients

This prospective, interventional study examined the impact of training for the WTG on levels of health-related physical fitness and habitual activity in a cohort of pediatric SOT recipients. Physical fitness (FitnessGram(®) ) and habitual activity (HAES) measures were performed on participants (n = 19) in the WTG and compared to non-participant controls (n = 14) prior to and following the WTG. Pre-WTG exercise training was provided to participants. Participants demonstrated a statistically significant improvement in their habitual weekday (6.1 ± 1.7 to 8.5 ± 1.9 h; p = 0.002) and weekend (6.3 ± 2.6 to 8.4 ± 2.5 h; p = 0.01) activity over the training period, while controls improved weekday activity only (6.3 ± 2.0 to 8.3 ± 2.1 h; p = 0.05. Weekend activity: 7.7 ± 2.7 to 8.3 ± 2.3 h; p = 0.68). Participants demonstrated a non-statistical improvement in select physical fitness parameters; however, a greater number of participants achieved healthy criterion standards for cardiovascular fitness (2 vs. 1), abdominal strength (5 vs. 3), and upper body strength (7 vs. 3) following training and participating in the WTG. The WTG can provide a positive incentive for greater levels of physical activity and promote improvements in physical fitness levels. Further study is needed to examine long-term impact on lifestyle changes and health outcomes.

Solid organ transplant recipients: clinical considerations in the application of exercise

Over 100 000 solid organ transplants are performed worldwide each year and this has a significant impact on physical function and quality of life. However, the capacity for exercise in solid-organ recipients is reduced. Regular physical activity improves most of the indices of fitness in these patients but, with few exceptions, they do not reach the values seen in healthy controls. The reason for the 40-60% reduction in maximal exercise capacity is not clear; the disease process, need for life long immunosuppression and sedentary lifestyle all contribute. The interaction between exercise and immunosuppressing medication merits research as does the specifics of the exercise prescription for these patients. This paper reviews important features of this rapidly expanding group of patients and suggests clinical considerations in the application of exercise in this population.

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.

Cardiopulmonary exercise testing in lung transplantation: a review

There has been an increase in lung transplantation in the USA. Lung allocation is guided by the lung allocation score (LAS), which takes into account one measure of exercise capacity, the 6-minute walk test (6MWT). There is a paucity of data regarding the role and value of cardiopulmonary stress test (CPET) in the evaluation of lung transplant recipients while on the transplant waiting list and after lung transplantation. While clearly there is a need for further prospective investigation, the available literature strongly suggests a potential role for CPET in the setting of lung transplant.

Lung transplantation and lung volume reduction surgery

Since the publication of the last edition of the Handbook of Physiology, lung transplantation has become widely available, via specialized centers, for a variety of end-stage lung diseases. Lung volume reduction surgery, a procedure for emphysema first conceptualized in the 1950s, electrified the pulmonary medicine community when it was rediscovered in the 1990s. In parallel with their technical and clinical refinement, extensive investigation has explored the unique physiology of these procedures. In the case of lung transplantation, relevant issues include the discrepant mechanical function of the donor lungs and recipient thorax, the effects of surgical denervation, acute and chronic rejection, respiratory, chest wall, and limb muscle function, and response to exercise. For lung volume reduction surgery, there have been new insights into the counterintuitive observation that lung function in severe emphysema can be improved by resecting the most diseased portions of the lungs. For both procedures, insights from physiology have fed back to clinicians to refine patient selection and to scientists to design clinical trials. This section will first provide an overview of the clinical aspects of these procedures, including patient selection, surgical techniques, complications, and outcomes. It then reviews the extensive data on lung and muscle function following transplantation and its complications. Finally, it reviews the insights from the last 15 years on the mechanisms whereby removal of lung from an emphysema patient can improve the function of the lung left behind.

Benefits of home-based endurance training in lung transplant recipients

BACKGROUND

To investigate the effect of home-based exercise training on exercise tolerance, muscle function and quality of life in lung transplant recipients (LTR).

METHODS

Twelve LTR and 7 age-matched healthy subjects underwent exercise training (ET, 12-wk, 3×/wk, 40 min). Peak aerobic capacity VO2peak, endurance time (T(end)), minute ventilation (VE) quadriceps strength, percentage of type I fiber (%Ifb), fiber diameters and chronic respiratory questionnaire were assessed before and after ET. A positive response to ET was defined as an improvement in T(end) at least comparable to the mean change observed in healthy subjects.

RESULTS

Training significantly improved T(end) (+12 ± 11 min), isowatt during exercise (-5.5 ± 2.6L/min), muscle strength (+4.6 ± 2.6 kg) and dyspnea score (+0.6 ± 0.9) in LTR (p < 0.05), leading to recovery of T(end) and muscle strength up to healthy subjects' values. In responders (n = 6), VO2peak, %Ifb and fatigue score were improved after training (p < 0.05). Non-responders had lower %Ifb and greater delay between surgery and the beginning of the study than responders (56 [21-106] vs. 8 [2-59] months respectively, p = 0.03).

CONCLUSIONS

Home-based ET was effective to improve exercise tolerance, muscle strength and quality of life in LTR but more successful in patients with moderate muscle dysfunction and in the first years after transplantation. Multicenter and controlled-studies are needed to confirm the benefits and optimal modalities of home training in LTR.

Comparison of wait times and mortality for idiopathic pulmonary fibrosis patients listed for single or bilateral lung transplantation

BACKGROUND

Lung transplantation is the one form of solid-organ transplantation in which there is the option for patients to receive one or two organs. Idiopathic pulmonary fibrosis (IPF) candidates can be accommodated by either procedure but the decision about these two options remains controversial. Therefore, we sought to determine whether IPF patients listed for bilateral lung transplantation only had longer wait times and higher mortality on the waiting list than those listed for single lungs only. Patients with chronic obstructive pulmonary disease (COPD) were also analyzed as a comparison group.

METHODS

This study was a retrospective analysis of the Organ Procurement and Transplantation Network database of patients with IPF and COPD listed for lung transplantation between May 2005 and December 2007. An analysis of wait times and mortality in this era as well as the pre-lung allocation score (pre-LAS) era of 2002 to 2004 was performed.

RESULTS

Of the 1,339 patients with IPF listed for lung transplantation, 31.7% were listed for bilateral lung transplantation only, 41% for single-lung transplantation only and 27.3% for either procedure. Patients listed for the bilateral procedure only were at greater risk of dying on the transplant list (p < 0.003), and were less likely to receive a lung transplant (p < 0.012). No difference in outcomes was seen in the COPD patients. Comparatively, in the pre-LAS era, wait times and mortality on the list for IPF patients were significantly greater for all forms of transplantation.

CONCLUSIONS

There has been a significant improvement in wait times and mortality for IPF patients since the inception of the LAS system. Nonetheless, despite the goal of transplant equity, IPF patients listed for bilateral lung transplantation might have a clinically meaningful increased risk of pre-transplant mortality. The choice of procedures therefore needs to be made with careful consideration of patients' survival both pre- and post-transplantation. Evaluation of transplant outcomes should not only be based on post-transplant survival, but should also account for the impact of the choice of procedure.

Exercise training after lung transplantation: a systematic review

BACKGROUND

Lung transplant recipients experience persistent impairments in exercise capacity and skeletal muscle function despite a vast improvement in lung function after transplantation. Exercise training may be beneficial in improving exercise capacity in lung transplant recipients. A systematic review was undertaken to examine the evidence for exercise training on functional outcomes in lung transplant recipients.

METHODS

Studies were identified by searching electronic databases and scanning reference lists. Only randomized controlled trials, controlled trials, and prospective cohorts were included in the review. Seven studies met the inclusion criteria. Study quality was assessed using the Physiotherapy Evidence Database, Jadad, and Downs scales.

RESULTS

The overall quality of studies was fair to moderate in assessing the effect of exercise training on maximal and functional exercise capacity, skeletal muscle function, and lumbar bone mineral density. Every study reported significant improvements in these outcomes. Some studies lacked randomization and/or a control group, so it was not possible to separate the effects of training with the natural recovery process after lung transplantation.

CONCLUSION

Some evidence was found to support that a period of structured exercise training could improve maximal and functional exercise capacity, skeletal muscle strength, and lumbar bone mineral density in lung transplant recipients. Further studies are needed to determine the potential for exercise training to optimize these functional outcomes and to develop optimal guidelines for exercise prescription in the lung transplant population.

Survival after bilateral versus single lung transplantation for patients with chronic obstructive pulmonary disease: a retrospective analysis of registry data

BACKGROUND

Both single and bilateral lung transplantation are recognised options for patients who have end-stage chronic obstructive pulmonary disease (COPD); however, which procedure leads to longer survival remains unclear. We aimed to compare survival after each procedure by analysing data from the registry of the International Society for Heart and Lung Transplantation.

METHODS

We analysed data for 9883 patients with COPD, 3525 (35.7%) of whom underwent bilateral lung transplantation, and 6358 (64.3%) single lung transplantation, between 1987 and 2006. We accounted for possible selection bias with analysis of covariance, propensity-score risk adjustment, and propensity-based matching.

FINDINGS

Median survival after either type of lung transplantation for patients with COPD was 5.0 years (95% CI 4.8-5.2). Survival for patients who had lung transplantation before 1998 was 4.5 years (4.3-4.8), compared with 5.3 years (5.0-5.5) for those who had it after 1998 (p<0.0001). The proportion of patients who had bilateral lung transplantation increased from 101/467 (21.6%) in 1993 to 345/614 (56.2%) in 2006. Median survival time after bilateral lung transplantation was longer than that after single lung transplantation: 6.41 years (6.02-6.88) versus 4.59 years (4.41-4.76) (p<0.0001). Pretransplant characteristics of patients who had single and bilateral lung transplantation differed, but whichever method was used to adjust for baseline differences, bilateral lung transplantation was associated with longer survival than was single lung transplantation; the hazard ratio ranged from 0.83 (0.78-0.92) for analysis of covariance to 0.89 (0.80-0.97) for propensity-based matching. However, bilateral lung transplantation had little benefit compared with single lung transplantation for patients who were 60 years and older (HR 0.95; 0.81-1.13).

INTERPRETATION

Bilateral lung transplantation leads to longer survival than single lung transplantation in patients with COPD, especially those who are younger than 60 years.

Surgical interventions for emphysema

Three surgical procedures are pertinent to the treatment of end-stage emphysema: giant bullectomy, lung volume reduction surgery (LVRS), and lung transplantation. Patients with localized disease manifesting as a giant bulla that compresses adjacent healthy lung tissues can be offered bullectomy. Patients with diffuse disease can be offered LVRS, lung transplantation, or staged LVRS/lung transplant, depending on multiple factors including age, lung function parameters, lobar predominance, and whether the disease is uni- or bilateral. Since end-stage emphysema is refractory to most medical treatment, surgery is often the only remaining option.

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.

Functional coupling of adenine nucleotide translocase and mitochondrial creatine kinase is enhanced after exercise training in lung transplant skeletal muscle

Mechanisms responsible for limitation of exercise capacity in lung transplant recipients (LR) and benefits gained by exercise training were studied. Mitochondrial respiration parameters, energy transfer, and cell structure were assessed in vastus lateralis biopsies using the permeabilized fiber technique with histochemical and morphometric measurements. Twelve male controls (C) and 12 LR performed exercise training over 12 wk. Before exercise training, there were strong correlations between exercise capacity (maximal O2 consumption and endurance time at 70% maximal power output) and cellular events, as assessed by percentage of type I fibers and apparent Km for exogenous ADP. Anticalcineurins were not involved in LR exercise limitation, since there were no differences in maximal mitochondrial rate of respiration before exercise training and no abnormalities in respiratory chain complexes compared with C. Training resulted in a significant increase in physiological parameters both at the cellular (apparent Km for exogenous ADP and stimulating effect of creatine) and integrated (maximal O2 consumption, power output at ventilatory threshold, maximal power output, and endurance time at 70% maximal power output) levels in LR and C. After the training period, improvements in maximal O2 consumption and in maximal mitochondrial rate of respiration were noted, as well as changes in endurance time and percentage of type I fibers. Because there were no changes in diameters and fiber types, baseline alteration of apparent Km for exogenous ADP and its improvement after training might be related to changes within the intracellular energetic units. After the training period, intracellular energetic units exhibited a higher control of mitochondrial respiration by creatine linked to a more efficient functional coupling adenine nucleotide translocase-mitochondrial creatine kinase, resulting in better exercise performances in C and LR.

[Lung transplantation in patients with pulmonary fibrosis]

Lung transplantation has been developed over the last fifteen years as a therapeutic option for different forms of advanced-stage lung disease. Idiopathic pulmonary fibrosis is a good indication. For these patients, single lung transplantation is usually preferred, bilateral lung transplantation to a lesser extent. Survival is similar for these two types of transplantation. The post-transplantation survival in patients with pulmonary fibrosis is about 65-70% at one year and 40% at five years. This rate is lower than observed for COPD or cystic fibrosis. If there are no complications, the patient can recover nearly normal lifestyle. Among the different complications, reimplantation edema, infection, rejection, and bronchial complications predominate. Chronic rejection, also called obliterative bronchiolitis syndrome, is a later complication which can be observed in about half of the patients. Improvement in graft survival depends greatly in improvement in prevention and management of complications. Despite such complications, graft survival in fibrosis patients is greater than spontaneous survival on the waiting list; idiopathic fibrosis is associated with the highest mortality on the waiting list. Patients should be referred early for the pre-transplantation work-up because individual prognosis is very difficult to predict.

Impaired exercise performance after successful liver transplantation

BACKGROUND

Recipients of heart, lung, and kidney transplants have impaired peak exercise performance (peak Vo2 40% to 60% predicted, reduced anaerobic threshold [AT]) without evidence of ventilatory or cardiac limitations. The aim of this study was to determine whether similar exercise impairment occurs in liver transplant recipients.

METHODS

We studied eight healthy liver transplant recipients (age 42+/-9 [SD] years, 6 male, 31+/-13 months posttransplant). Immunosuppression included FK506 or cyclosporine, azathioprine or mycophenolate mofetil, and prednisone. Subjects underwent lung function testing and cardiopulmonary exercise testing on a cycle ergometer.

RESULTS

Peak exercise oxygen consumption (Vo2) was 22+/-8 ml/min/kg (66+/-20% predicted maximum). No subject demonstrated exercise desaturation or ventilatory limitation (peak minute ventilation 55+/-8% predicted maximum voluntary ventilation). Peak heart rate was 87+/-8% of predicted maximum. Early AT was evident (1.2+/-0.34 L/min, 48+/-11% predicted Vo2max).

CONCLUSIONS

Liver transplant recipients exhibit impaired peak exercise performance similar to that observed after other solid organ transplants, possibly as a result of chronic deconditioning or myopathy related to immunosuppressive medications.

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.

Complications in the native lung after single lung transplantation

OBJECTIVES

Single lung transplantation is a viable option for patients with end-stage pulmonary disease; despite encouraging results, we observed serious complications arising in the native lung. We retrospectively reviewed 36 single lung transplants to evaluate the incidence of complications arising in the native lung, their treatment and outcome.

METHODS

Between 1991 and 1997, 35 patients received 36 single lung transplants for emphysema (16), pulmonary fibrosis (14), lymphangioleiomyomatosis (4), primary pulmonary hypertension (1) and bronchiolitis obliterans (1). The clinical records were reviewed and the complications related to the native lung were divided into early (up to 6 weeks after the transplant) and late complications.

RESULTS

Nineteen complications occurred in 18 patients (50%), leading to death in nine (25%). Early complications (within 6 weeks from the transplant) were bacterial pneumonia (1), overinflation (3), retention of secretions with bronchial obstruction and atelectasis (1), hemothorax (1), pneumothorax (1) and invasive aspergillosis (3); one patient showed active tuberculosis at the time of transplantation. Two patients developed bacterial pneumonia and invasive aspergillosis leading to sepsis and death. The other complications were treated with separate lung ventilation (1), bronchoscopic clearance (1), chest tube drainage (1) and wedge resection and pleurodesis (mechanical) by VATS (1). One patient with hyperinflation of the native lung eventually required pneumonectomy and died of sepsis. The patient with active tuberculosis is alive and well after 9 months of medical treatment. Late complications were recurrent pneumothorax (4), progressive overinflation with functional deterioration (2), aspergillosis (1) and pulmonary nocardiosis (1). Recurrent pneumothorax was treated with chest tube drainage alone (1), thoracoscopic wedge resection and/or pleurodesis (2) and pneumonectomy (1); hyperinflation was treated with thoracoscopic lung volume reduction in both cases; both patients with late infectious complications died.

CONCLUSIONS

After single lung transplantation, the native lung can be the source of serious problems. Early and late infectious complications generally result in a fatal outcome; the other complications can be successfully treated in most cases, even if surgery is required.

Effect of NO, vasodilator prostaglandins, and adenosine on skeletal muscle angiogenic growth factor gene expression

Exercise training results in several muscle adaptations, one of which is angiogenesis. Acutely, exercise leads to release of nitric oxide, prostacyclin (PGI2), and adenosine (A) in the skeletal muscles. In this paper, we asked whether any of these locally released vasodilators, as well as other known dilator prostaglandins (PGE1 and PGE2), have the potential to increase angiogenic growth factor gene expression in resting skeletal muscle. Seven groups of 5-7 female Wistar rats (age 8-12 wk, weight 250 +/- 10 g) were anesthetized and instrumented for carotid artery pressure and electromagnetic femoral artery blood flow measurement. One group acted as control while the other groups each received one of the following six agents by constant arterial infusion (dose in microg/min): A (200), nitroprusside (NP, 4.2), acetylcholine (100), PGE1 (1.9), PGE2 (1.7), and PGI2 (1.7). Each agent reduced peripheral vascular resistance to a similar extent (at least twofold). Densitometric mRNA/18S levels for vascular endothelial growth factor (VEGF) were increased 50% by NP and acetylcholine, were unaffected by PGE1 and PGE2, and were reduced 40% by PGI2. For basic fibroblast growth factor, only PGI2 had any effect, reducing mRNA/18S approximately 25%. For transforming growth factor-beta1, A, NP, and PGE1 led to reduced mRNA/18S, whereas PGE2 slightly increased mRNA/18S. For the principal putative angiogenic growth factor, VEGF, these data suggest that naturally secreted vasodilators in contracting skeletal muscle could be involved in regulation of gene expression, namely, nitric oxide in a positive and PGI2 in a negative direction.

Chest size matching in single and double lung transplantation

We applied predicted vital capacity to chest size matching between donor and recipient in lung transplantation to 15 single-lung transplant recipients with pulmonary fibrosis and to 20 double-lung transplant recipients with emphysema or non-emphysema. The predicted vital capacity of the donor was significantly correlated with the predicted vital capacity of the recipient both in double-lung transplantation (r = 0.79, p = 0.001) and single-lung transplantation (r = 0.71, p = 0.003). In double-lung transplantation, the post-transplant vital capacity was correlated with the predicted vital capacity of the recipient (r = 0.74, p = 0.002). Emphysema patients and non-emphysema patients contributed equally to this correlation. In left single lung transplantation, there was a weak correlation between the post-transplant vital capacity and the predicted vital capacity of the donor in the allograft (r = 0.57, p = 0.1095). In right single lung transplantation, the post-transplant vital capacity of the allograft tended to be correlated with the predicted vital capacity of recipient (r = 0.77, p = 0.0735). We concluded that donors were actually selected based on the comparison of predicted vital capacity between donor and recipient. In double-lung transplantation, the post-transplant vital capacity was limited by the recipient's normal thoracic volume and was not influenced by underlying pulmonary disease. In single-lung transplantation with pulmonary fibrosis, the allograft transplanted in the left chest could expand to its own size, and the allograft transplanted in the right chest could expand to the recipient's normal thoracic volume as in double-lung transplantation.

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.

Maximal exercise capacity and peripheral skeletal muscle function following lung transplantation

BACKGROUND

There have been many suggestions that diminished exercise capacity in patients that have undergone lung transplantation is due, in part, to peripheral muscle dysfunction, brought on by either detraining or immunosuppressive therapy. There is limited data quantifying skeletal muscle function in this population, especially in those more than 18 months post-procedure. The present study sought to quantitate skeletal muscle function and cardiopulmonary responses to graded exercise in 19 lung transplant recipients, 15 of which were mostly more than 18 months post-procedure.

METHODS

Ten single- (SLT) and 9 double-lung transplantation (DLT) underwent anthropometric measures and performed expiratory spirometry, whole body plethysmography to assess lung volumes, static maximal mouth pressures to assess respiratory muscle strength, progressive exercise testing on a cycle ergometer (with cardiac output measurements being performed every second workload) and isokinetic cycling to assess peripheral muscle power and work capacity.

RESULTS

The DLT group was younger than the SLT group (23.0 [21.0-32.0] vs 47.5 [43.0-55.0] median [interquartile range], p < .05) with no differences in height, weight, or BMI. Despite the DLT group having significantly better spirometric values (FEV1: 86% vs 56.5% median) and less airtrapping (RV/TLC: 30% vs 53.5%), both groups were equally limited in exercise capacity (Wmax)(38.0 percent predicted [30.0-65.0] vs 37.5 percent predicted [30.0-44.0], SLT vs DLT), leg power (76.1 percent predicted [53.8-81.4] vs 69.0 percent predicted [58.3-76.0]) and leg work capacity (63.3 percent predicted [34.7-66.8] vs 38.4 percent predicted [27.5-57.3]). This lack of difference in performance persisted when the analysis was limited to those more than 18 months post-procedure. Respiratory muscle strength was also not different for the two groups, and was within normal limits. Wmax was best correlated with leg work capacity (r = .84), but also with leg power, RV/TLC, FEV1 (r = .49, -.52, .58). When normalized for age, height, and sex, percent predicted Wmax only correlated with percent predicted leg work capacity (r = .58). Cardiac output was appropriate for the work performed.

CONCLUSIONS

We conclude that peripheral skeletal muscle work capacity is reduced following lung transplantation and mostly responsible for the limitation of exercise performance. While the causes of muscular dysfunction have yet to be clarified, the preservation of respiratory muscle strength with the concomitant reduction in leg power and work capacity suggests that most of the muscular dysfunction post-transplantation is attributable to detraining.

Exercise and organ transplantation

Life-saving treatment of disease by organ transplantation has become increasingly important. Annually over 35,000 transplantations of vital organs are carried out world-wide and the demand for knowledge regarding exercise in daily life for transplant recipients is growing. The present review describes whole-body and organ reactions to both acute exercise and regular physical training in persons who have undergone heart, lung, liver, kidney, pancreas or bone marrow transplantation. In response to acute exercise, the majority of cardiovascular, hormonal and metabolic changes are maintained after transplantation. However, in heart transplant recipients organ denervation reduces the speed of heart rate increase in response to exercise. Furthermore, lack of sympathetic nerves to transplanted organs impairs the normal insulin and renin responses to exercise in pancreas and kidney transplant recipients, respectively. In contrast, surgical removal of sympathetic liver nerves does not inhibit hepatic glucose production during exercise, and denervation of the lungs does not impair the ability to increase ventilation during physical exertion. Most studies show that physical training results in an improved endurance and strength capacity in almost all groups of transplant recipients, which is of importance for their daily life. With a little precaution, organ transplant recipients can perform exercise and physical training and obtain effects comparable with those achieved in the healthy population of similar age.

Cellular adaptations of skeletal muscles to cyclosporine

The aim of this study was to evaluate the cellular response of the diaphragm, extensor digitorum longus (EDL), and soleus (Sol) muscles to clinically relevant doses of cyclosporine administered to male rats over 4 wk. Control rats were provided with vehicle only. Muscle fiber types, cross-sectional areas, indexes of capillarity, and succinate dehydrogenase (SDH) activity were determined by quantitative histochemistry. Myosin heavy chain isoforms were identified by SDS-PAGE, and their proportions were measured by scanning densitometry. Serum cyclosporine level, 20-24 h after the last dose of cyclosporine, was 145 +/- 81 ng/ml. Final body weight and muscle mass were similar between the cyclosporine and control groups. In the diaphragm, EDL, and Sol, no differences were observed between the groups with regard to fiber type proportions, fiber cross-sectional areas, and proportions of myosin heavy chain isoforms. In the EDL, reductions, both in SDH activity in type I, IIx, and IIb fibers (-26 to -37%) and in indexes of capillarity (-18 to -37%), were noted. In the Sol, SDH activity and capillarity were similar between the groups. In the diaphragm of cyclosporine-treated rats, there was significant reduction in the number of capillaries around individual fibers (-5%), whereas levels of SDH activity tended to be lower. This suggests that activation history may in part determine muscle-specific responses to cyclosporine. We speculate that reduced oxidative activity and capillarity of some limb muscles contribute to reduced exercise capacity and the "deconditioned state" observed in patients receiving cyclosporine after successful solid-organ transplantation.

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.

Preoperative and postoperative imaging in the surgical management of pulmonary emphysema

For patients with emphysema, imaging studies have been useful for diagnostic purposes and for preoperative patient selection for surgical intervention, such as bullectomy, lung transplantation, and LVRS. Chest radiography is useful in evaluating hyperinflation. Inspiratory and expiratory films are used to estimate diaphragmatic excursion and air-trapping. CT scan is used to evaluate the anatomy and distribution of emphysema throughout the lungs, providing information clinically unobtainable by other means. Both imaging techniques are useful for detecting other disease processes. Radionuclide lung scanning also provides an estimate of target areas, volume occupying but nonfunctioning lung. Cohort studies utilizing these imaging techniques have demonstrated associations between preoperative characteristics and postoperative outcome. The imaging studies, especially the chest radiograph, have also played an important role in postoperative management. Many other imaging options are available, such as HRCT scan, quantitative CT scan, and single photon emission CT scan. Other techniques, such as MR imaging, may play a future role as well.

Comparison of the functional results of single lung transplantation for pulmonary fibrosis and chronic airway obstruction

BACKGROUND

Single lung transplantation (SLT) is now a treatment option for patients with both pulmonary fibrosis and advanced chronic airway obstruction. Lung function after transplantation might be expected to be different in these two groups of patients because of the effect of the remaining native lung, but the implications of these differences have not been fully explored.

METHODS

The functional results of a stable population of 20 patients (13 chronic airway obstruction, seven pulmonary fibrosis) after SLT with no evidence of obliterative bronchiolitis were analysed. The differences between the two populations in the interrelations between and determinants of total lung capacity (TLC), subdivisions of lung volume, airway function (spirometry, maximum expiratory flow volume curves, and moments analysis of the spirogram) respiratory mechanics (PV curves and maximal respiratory pressures), CO transfer factor (TLCO) and the distribution of perfusion, ventilation and volume of the transplanted and native lungs were compared.

RESULTS

Total lung capacity after SLT (TLCpost) was normal in the patients with pulmonary fibrosis (mean (SE) 103.9 (6.9)% predicted) but remained significantly elevated in patients with airway obstruction (126.4 (4.4)%. Forced expiratory volume in one second (FEV1) and vital capacity (VC) improved to similar values after SLT in both groups with a final VC of 76.8 (5.9)% and 66.7 (3.9)% in patients with fibrosis and airway obstruction, respectively. Maximum expiratory flows were generally lower and moments analysis of the spirogram showed slower lung emptying with significantly greater second and third moments (alpha 2 and alpha 3) in patients with airway obstruction. Relative ventilation and perfusion of the transplanted lung were both greater in both populations but relative ventilation of the transplanted lung was significantly greater in patients treated for airway disease than in those with pulmonary fibrosis. TLCO was also significantly higher in patients who had received a transplant for chronic airway obstruction.

CONCLUSIONS

These results suggest that differences in the functional results of SLT for airway disease and pulmonary fibrosis are relatively minor. In this series the native hyperinflated lung in chronic airway disease was not more disadvantageous to overall function than the native lung in pulmonary fibrosis. However, tests of lung function based on the terminal portion of the forced spirogram are likely to be less sensitive for the detection of obliterative bronchiolitis in patients who have received a transplant for advanced airway obstruction than in those with pulmonary fibrosis.

Early and long-term functional outcomes in unilateral, bilateral, and living-related transplant recipients

Lung transplantation offers the possibility of improved quality of life and survival in patients with severe pulmonary and pulmonary vascular disease. Since the first human lung allotransplantation in 1963, survival has moved from hours or days into the present era of long-term (years) survival in many recipients. Measurement of outcome has now extended to measurement of exercise capacity and quality of life. A substantial improvement in quality of life is seen; however, exercise capacity remains moderately impaired in spite of the return (in many) of near normal cardiopulmonary function, suggesting peripheral limitation to exercise. Recently, fiber type changes and abnormal oxidative metabolism have been shown in the skeletal muscle of stable lung transplant recipients. This suggests a persistence of a pretransplant skeletal muscle injury and/ or the effects of post-transplant immunosuppression (particularly Cyclosporin A and corticosteroids).

Lung transplantation: selection of patients and analysis of outcome

Lung transplantation is an important option for patients with respiratory failure and limited life expectancy. Herein we review the current indications for and outcome after lung transplantation. These results are compared with the natural history of various respiratory diseases, estimated from available databases. Candidates for lung transplantation are generally younger than 60 years of age, have a limited life expectancy because of end-stage lung disease, and have no other major organ dysfunction. Single lung transplantation is performed most commonly for emphysema, pulmonary fibrosis, and pulmonary hypertension. Survival after single lung transplantation is approximately 70% at 1 year, 60% at 2 years, and 40% at 3 years. The median duration of survival for patients with end-stage lung diseases ranges from approximately 2 to 6 years, with wide variation based on the diagnosis and severity of illness. Currently, prolongation of the average survival has not been clearly substantiated after lung transplantation. Further evaluation of outcomes, functional status, and quality of life after lung transplantation is necessary.

Exercise testing in pediatric heart, heart-lung, and lung transplant recipients

Cardiorespiratory responses to progressive exercise were examined in 38 children who had undergone heart (n = 16), heart-lung (n = 13), or double-lung (n = 9) transplantation, and in 41 healthy controls. The four groups were similar in age, but the control subjects and heart transplant recipients were significantly larger than the heart-lung and lung recipients as assessed by body mass index (BMI). Time since transplant was significantly longer in the heart (601 days) compared with heart-lung (146 days) and lung (125 days) transplant groups. Physical work capacity and peak oxygen uptake were significantly reduced (43 to 64% of predicted) in the three transplant groups compared with the control group. Peak heart rate (percent predicted) was significantly higher in the control subjects (94%) compared with the heart (66%), heart-lung (70%), and lung (77%) transplant recipients. Peak minute ventilation was significantly higher in the control (72.9 L/min) and heart transplant (51.0 L/min) groups than the heart-lung (37.4 L/min) and lung (41.3 L/min) transplant groups. The control group had a higher peak tidal volume than the three transplant groups, and a higher peak respiratory rate than the lung transplant recipients. Correlational analysis revealed that physical work capacity (PWC) was significantly related to heart rate at peak exercise (HRpeak) and minute ventilation at peak exercise (VE-peak) in the heart transplant recipients, BMI, VEpeak, and FEV1 in the heart-lung transplant recipients, and BMI, HRpeak, VEpeak, FEV1, and number of days posttransplant in the lung transplant recipients. In addition to these variables, physical deconditioning and factors related to pharmacotherapy, infection, and rejection may also contribute to the decreased PWC observed in the transplant recipients.

Outcome of the native lung after single lung transplant. Multiorgan Transplant Group

Twenty-one long-term survivors of single lung transplant since 1987 have been followed from 7 to 81 months. Posttransplant complications unique to the native lung and their impact on patient outcome are reported. In 7 of 21 recipients of single lung transplant, clinical complications in the native lung developed, including infection, pulmonary infarction, and severe ventilation-perfusion mismatching. Impact on the patient has ranged from little effect (prolongation of hospital or ICU stay) to recurrent severe infections, the need for surgical intervention, and a possible contribution to the recurrence of original disease--giant cell interstitial pneumonitis. The remaining native lung can be a source of significant complications following single lung transplant. Pretransplant diagnoses other than uncomplicated idiopathic pulmonary fibrosis seem to be most frequently associated with compromise of function or risk of infection arising from the native lung.

Cardiopulmonary exercise testing following allogeneic lung transplantation for different underlying disease states

OBJECTIVES

To assess the exercise response to single lung transplantation in chronic airflow obstruction (CAO), idiopathic pulmonary fibrosis (IPF), and pulmonary vascular disease (PVD) vs double lung transplantation at well-defined time points after transplantation, and to define the change in exercise response in SLT and DLT over the first year after transplantation.

DESIGN

Prospective study.

SETTING

Tertiary referral hospital.

PATIENTS

Fourteen stable SLT recipients (6 with CAO, 4 with IPF, 4 with PVD) and 11 stable DLT recipients.

MEASUREMENTS

Spirometry, lung volumes, diffusion lung capacity for carbon monoxide (DLco) and MVV measured prior to exercise at 3 months (n = 25) then at 3-month intervals up to a maximum of 12 months post-transplantation (n = 18 [12 SLT and 6 DLT]). Symptom-limited cardiopulmonary exercise tests at same time points (n = 25 at 3 months, n = 18 [12 SLT and 6 DLT] at 3-month intervals up to 12 months). Breathlessness was estimated by visual analogue scale prior to exercise and at peak exercise.

RESULTS

At 3 months, FEV1 percent predicted was lower for SLT-CAO and SLT-IPF vs DLT (p < or = 0.05). Mean FEV1/FVC was lower for SLT-CAO vs all other groups (p < or = 0.05). The FVC, MVV, and DLco/VA were similar for all groups. The TLC and RV were higher for the SLT-CAO group compared with all others. The TLC was lower for SLT-PVD compared with DLT. Exercise responses were similar in all groups studied without a statistically significant difference in achieved VO2, work rate, O2 pulse, anaerobic threshold, heart rate response, respiratory rate, VE/MVV, and VT/VC. The change in O2 saturation during exercise was the least in recipients of DLT. Maximal achieved VO2 rose from 3 to 6 months after SLT but dropped by 9 to 12 months after transplantation. Maximal achieved VO2 trended up from 3 to 6 months after DLT but dropped by 9 to 12 months after transplantation. Maximal achieved work rate rose in both SLT and DLT from 3 to 9 to 12 months after transplantation. There was no significant difference in breathlessness at rest and peak exercise measured between recipients of SLT or DLT.

CONCLUSIONS

Minor differences in pulmonary function and change in O2 saturation occur between recipients of SLT and DLT during the first posttransplant year. These differences are most pronounced when comparing SLT-CAO with DLT. However, there is no significant difference in exercise capacity between SLT for CAO, IPF, PVD, and DLT. The rise in maximum achieved VO2 over the first 6 months after transplantation may reflect the effects of exercise training and should be taken into account when examining aerobic response after transplantation.

Echocardiographic assessment of right and left ventricular function after single-lung transplantation

To evaluate the impact of single-lung transplantation on right and left ventricular performance and to identify potential preoperative characteristics that could predict postoperative outcome, a large group of patients were retrospectively evaluated by means of serial Doppler echocardiography. Twenty-six of 57 consecutive single-lung transplant patients had satisfactory Doppler echocardiographic studies before and after surgery. A significant reduction in right ventricular diastolic and systolic areas and an increase in right ventricular fractional area were noted after transplantation. The left ventricular contractility remained unchanged. In addition, significant reduction in right atrial area, right ventricular free wall thickness, and tricuspid regurgitation were also seen. Paradoxical septal motion present in eight patients before the procedure resolved in all of them after single-lung transplantation. Transthoracic echocardiography is a useful technique to document improvement in right ventricular function in 63% of patients following single-lung transplantation. Preoperative paradoxical septal motion identifies single-lung transplant recipients who have the largest postoperative right ventricular area reduction and fractional area increase. Alternative imaging modalities should be sought for single-lung transplant candidates in whom conventional transthoracic echocardiography is suboptimal.