Physiologic aspects of human heart-lung transplantation. Pulmonary function status of the post-transplanted lung

Effects of donor smoking history on early post-transplant lung function measured by oscillometry

Introduction

Prior studies assessing outcomes of lung transplants from cigarette-smoking donors found mixed results. Oscillometry, a non-invasive test of respiratory impedance, detects changes in lung function of smokers prior to diagnosis of COPD, and identifies spirometrically silent episodes of rejection post-transplant. We hypothesise that oscillometry could identify abnormalities in recipients of smoking donor lungs and discriminate from non-smoking donors.

Methods

This prospective single-center cohort study analysed 233 double-lung recipients. Oscillometry was performed alongside routine conventional pulmonary function tests (PFT) post-transplant. Multivariable regression models were constructed to compare oscillometry and conventional PFT parameters between recipients of lungs from smoking vs non-smoking donors.

Results

The analysis included 109 patients who received lungs from non-smokers and 124 from smokers. Multivariable analysis identified significant differences between recipients of smoking and non-smoking lungs in the oscillometric measurements R5-19, X5, AX, R5z and X5z, but no differences in %predicted FEV1, FEV1/FVC, %predicted TLC or %predicted DLCO. An analysis of the smoking group also demonstrated associations between increasing smoke exposure, quantified in pack years, and all the oscillometry parameters, but not the conventional PFT parameters.

Conclusion

An interaction was identified between donor-recipient sex match and the effect of smoking. The association between donor smoking and oscillometry outcomes was significant predominantly in the female donor/female recipient group.

Lung Transplantation and Precision Medicine

Lung transplantation is an accepted therapeutic option for end-stage lung diseases. Its history starts in the 1940s, initially hampered by early deaths due to perioperative problems and acute rejection. Improvement of surgical techniques and the introduction of immunosuppressive drugs resulted in longer survival. Chronic lung allograft dysfunction (CLAD), a new complication appeared and remains the most serious complication today. CLAD, the main reason why survival after lung transplantation is impaired compared to other solid-organ transplantations is characterized by a gradually increasing shortness of breath, reflected in a deterioration of pulmonary function status, respiratory insufficiency and possibly death.

Aspects of Anesthesia for Lung Transplantation

Anesthesia for lung transplantation is both a demand ing and rewarding experience. Success requires team- work, experience, knowledge of cardiorespiratory patho physiology and its anesthetic implications, appropriate use of noninvasive and invasive monitoring, and the ability to respond quickly and effectively to life- threatening perioperative events. Specific issues in clude management of a patient with end-stage lung and heart disease, lung isolation and one-lung ventilation, perioperative respiratory failure, pulmonary hyperten sion, and acute right ventricular failure. Recent ad vances include greater understanding of dynamic hyper inflation ("gas-trapping") during mechanical ventilation, perioperative use of inhaled nitric oxide and treatment of acute right ventricular failure. Successful anesthetic management leads to greater hemodynamic stability, improvement in gas exchange and a reduction in need for cardiopulmonary bypass, all of which should lead to improved patient outcome.

Restrictive chronic lung allograft dysfunction: Where are we now?

Chronic lung allograft dysfunction (CLAD) remains a frequent and troublesome complication after lung transplantation. Apart from bronchiolitis obliterans syndrome (BOS), a restrictive phenotype of CLAD (rCLAD) has recently been recognized, which occurs in approximately 30% of CLAD patients. The main characteristics of rCLAD include a restrictive pulmonary function pattern with a persistent decline in lung function (FEV1, FVC and TLC), persistent parenchymal infiltrates and (sub)pleural thickening on chest CT scan, as well as pleuroparenchymal fibroelastosis and obliterative bronchiolitis on histopathologic examination. Once diagnosed, median survival is only 6 to 18 months compared with 3 to 5 years with BOS. In this perspective we review the historic evidence for rCLAD and describe the different diagnostic criteria and prognosis. Furthermore, we elaborate on the typical radiologic and histopathologic presentations of rCLAD and highlight risk factors and mechanisms. Last, we summarize some opportunities for further research including the urgent need for adequate therapy. In this perspective we not only assess the current knowledge, but also clarify the existing gaps in understanding this increasingly recognized complication after lung transplantation.

Supranormal expiratory airflow after bilateral lung transplantation is associated with improved survival

RATIONALE

flow volume loops (FVL) in some bilateral lung transplant (BLT) and heart-lung transplant (HLT) patients suggest variable extrathoracic obstruction in the absence of identifiable causes. These FVLs usually have supranormal expiratory and normal inspiratory flow rates (SUPRA pattern).

OBJECTIVES

characterize the relationship of the SUPRA pattern to predicted donor and recipient lung volumes, airway size, and survival.

METHODS

we performed a retrospective review of adult BLT/HLT patients. We defined the SUPRA FVL pattern as: (1) mid-vital capacity expiratory to inspiratory flow ratio (Ve50:Vi50) > 1.0, (2) absence of identifiable causes of extrathoracic obstruction, and (3) Ve50/FVC ≥ 1.5 s(-1). We calculated predicted total lung capacity (pTLC) ratio by dividing the donor pTLC by the recipient pTLC. We measured airway luminal areas on thoracic computer tomographic scans. We compared survival in patients with and without the SUPRA pattern.

MEASUREMENTS AND MAIN RESULTS

the SUPRA FVL pattern occurred in 56% of the 89 patients who qualified for the analysis. The pTLC ratio of SUPRA and non-SUPRA patients was 1.11 and 0.99, respectively (P = 0.004). A higher pTLC ratio was correlated with increased probability of the SUPRA pattern (P = 0.0072). Airway luminal areas were larger in SUPRA patients (P = 0.009). Survival was better in the SUPRA cohort (P = 0.009).

CONCLUSIONS

the SUPRA FVL pattern was frequent in BLT/HLT patients. High expiratory flows in SUPRA patients could result from increased lung elastic recoil or reduced airway resistance, both of which could be caused by the pTLC mismatch. Improved survival in the SUPRA cohort suggests potential therapeutic approaches to improve outcomes in BLT/HLT patients.

[Long-term outcome of lung transplantation]

Lung transplantation (LTx) nowadays is an established therapeutic option for various end-stage lung diseases in despite of an optimal medical therapy in selected patients affected with various pathologies such as emphysema/chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF) and various forms of bronchiectasis, pulmonary fibrosis and pulmonary hypertension. Progress and refinement over the last two decades in both surgical techniques and medical management including especially the introduction of cyclosporine A, have been impressive. Patient survival improved significantly over time. According to the most recent data of the International Registry of Lung Transplantation (ISHLT), actuarial survival is 79%, 63%, 52% and 29% at 1, 3, 5 and 10 years respectively, with a current overall survival half-life of 5.3 years, and more than 7 years for those who survived 1 year or more. However, survival depends on different parameters such as the underlying disease, data relative to the donor, the recipient and/or the transplant procedure. Major limitation of long-term survival is still chronic allograft dysfunction, which is histologically represented by an obliterative bronchiolitis and functionally by the bronchiolitis obliterans syndrome (BOS). In uncomplicated cases near-normalization of pulmonary function is the rule, with more than 80% of survivors at 1, 3, 5 and 10 years reporting no activity limitations. Functional results after single LTx remain lower than those of the bilateral LTx, and depend on the potential worsening of the underlying disease and complications arising on the native lung. Exercise performance usually is approximately 50% of predicted, suggesting extrapulmonary causes such as side effects of immunosuppressive drugs. Quality of life improves significantly in all domains including employment status.

Sources of graft restriction after single lung transplantation for emphysema

OBJECTIVE

After single lung transplantation for emphysema, the volume of the graft at total lung capacity is usually less than its predicted volume in the donor. We sought to determine the contributions of donor-recipient size matching, postoperative native lung hyperinflation, and postoperative chest wall volume reduction to graft restriction after transplantation.

METHODS

In 19 patients, we estimated individual lung volumes from thoracic computed tomographs taken near total lung capacity before and after single lung transplantation for emphysema to analyze sources of graft restriction. Pulmonary function was assessed by spirometry, and in 5 patients, inspiratory function was assessed with esophageal manometry.

RESULTS

Graft volumes after transplantation were 54% +/- 17% of those predicted for the donors (mean +/- SD, P < .0001), and pulmonary function after transplantation was significantly correlated with graft volume. The greatest contribution to graft restriction was the decrease in chest wall volume after transplantation, which was -0.87 L (-31% +/- 29% of the graft's predicted volume; P < .0001). Volume expansion of the contralateral lung contributed -0.44 L (-18% +/- 24%; P = .0018). Other effects, including donor-patient size matching, were not significant. In 5 patients, the maximum negative inspiratory esophageal pressure at total lung capacity was low (-6 +/- 2 cm H2O, normal range approximately -17 to -29 cm H2O).

CONCLUSIONS

After single lung transplantation for emphysema, decreased volume of the chest wall was more important than increased volume of the native lung in causing restriction of the graft and decreased pulmonary function. Chest wall restriction is likely due to diminished inspiratory muscle function.

Anesthetic management of the pediatric patient undergoing solid organ transplantation

Solid organ transplantation is now routinely performed at many institutions. Pediatric organ recipients present difficult challenges to pediatric anesthesiologists. Physiologic, anatomic, and pharmacologic derangements in this population may make both the surgical procedure and the anesthetic management complicated. This article presents an overview of the unique problems and the strategies to solve them in this population.

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.

Altered lung mechanics after double-lung transplantation

We studied lung mechanics and small airways function in 15 patients after double-lung (DL) transplantation. Patients were classified as stable (DL-S, n = 11), or having obliterative bronchiolitis syndrome (DL-OBS, n = 4). We performed pulmonary function tests (PFT), measured slope of phase 3 of the single-breath nitrogen test (N2SP3), and obtained pressure-volume curves and values: chord compliance (Cst,L), specific chord compliance (SCst,L), and elastic recoil pressure at 90% TLC. PFT showed mild restrictive pattern in DL-S and severe obstructive lung disease in DL-OBS. The N2SP3 measurement indicated small airways dysfunction in 82% of DL-S and in all DL-OBS patients. The Cst,L was 0.24 +/- 0.08 L/cm H2O in DL-S and 0.16 +/- 0.05 L/cm H2O in DL-OBS, both lower than control subjects 0.34 +/- 0. 09 L/cm H2O (p < 0.01; p < 0.001). Moreover, SCst,L was 0.09 +/- 0. 03 cm H2O-1 in DL-S, and 0.05 +/- 0.02 cm H2O-1 in DL-OBS, significantly lower than control subjects 0.12 +/- 0.02 cm H2O-1 (p < 0.05; p < 0.001). Elastic recoil at 90% TLC was normal in 14 of 15 patients. We found a linear correlation between N2SP3 and FEV1, and between FEV1 and Cst,L and SCst,L for combined DL-S and DL-OBS. Reduced compliance near FRC with normal elastic recoil at high lung volumes does not suggest changes in lung parenchyma. We speculate that structural or functional alterations in small airways may have contributed to low compliance measurements. Of special concern are our findings that DL-S had significant small airways dysfunction and reduced compliance in a pattern similar to the DL-OBS, only smaller in magnitude.

Respiratory mechanics after heart-lung and bilateral lung transplantation

BACKGROUND

The factors determining respiratory mechanics following heart-lung transplantation (HLT) and bilateral lung transplantation (BLT) are incompletely understood.

METHODS

The dynamic and static lung volumes of 15 patients after HLT (n = 6) and BLT (n = 9) with no evidence of obliterative bronchiolitis were analysed to assess the factors which determine lung volumes following transplantation. Post-transplantation total lung capacity (TLCpost) was compared with the size of the recipient's lungs (TLCpre), the predicted capacity of the thorax of the recipient (TLCpred), and the predicted size of the donor's lungs (TLCdon). In addition, the post-transplantation respiratory mechanics were investigated by measuring the static pressure-volume (PV) curve of the lungs and the maximum respiratory pressures in a subgroup of nine patients (four HLT, five BLT).

RESULTS

TLCpost was closely related to TLCpred in both groups and showed no correlation with TLCpre. The mean (95% CI) TLCpost was 102.5 (90.2 to 115)% predicted for the recipient in the HLT group and 109 (97.6 to 120)% predicted for the recipient in the BLT group. Despite the near normal TLC, residual volume (RV) and functional residual capacity (FRC) remained increased after transplantation in both groups. These abnormalities were not attributable to either airflow obstruction or expiratory muscle weakness. On average, lung compliance expressed in terms of the shape constant of the static pressure-volume curve of the lungs was mildly reduced in both groups compared with values predicted for the recipient.

CONCLUSIONS

These results suggest that at high lung volumes the chest wall adapts to the size of transplanted lungs, while at lower volumes the increase in FRC and RV might be due to a persistent change in the static pressure-volume curve of the chest wall.

Anaesthesia for patients after lung transplantation

PURPOSE

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

SOURCE

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

PRINCIPLE FINDINGS

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

CONCLUSION

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

[Ventilation pattern at rest and respiratory response to hypercapnic stimulation after lung transplantation]

We aimed to assess breathing pattern at rest by studying occlusion pressure after the first 100 miliseconds (P0.1) and ventilatory response to hypercapnia after lung transplantation. Seven transplanted patients were compared with a control group of 7 healthy subjects. The breathing pattern at rest after transplantation included a significant increase in minute volume (VE) at the expense of an increase in tidal volume (VT) and above all of mean inspiratory flow (VT/Ti). There were no significant differences in ventilatory response to hypercapnia between the 2 groups, although the response curves of both VE and VT to CO2 tended to slope downward. These results can be explained by the mechanics of ventilation in some subjects studied and by the effect of pulmonary denervation on ventilatory control.

Ventilation-perfusion inequalities during graft rejection in patients undergoing single lung transplantation for primary pulmonary hypertension

We report herein data on single lung transplant (SLT) recipients with primary pulmonary hypertension (PPH). One patient did well following surgery but died on the 30th postoperative day due to cytomegalovirus pneumonia. The remaining two patients initially did well with unlimited exercise tolerance following transplantation, but then developed marked dyspnea on exertion and hypoxemia on postoperative days 144 and 120, respectively. Pulmonary function testing showed marked deterioration of function and transbronchial lung biopsy specimens revealed acute graft rejection in one patient and evidence of chronic graft rejection in the second patient. Quantitative ventilation-perfusion lung scanning demonstrated a marked decrease in ventilation to the transplanted lung in both cases associated with only a mild decrease in perfusion. This V/Q mismatch resulted in markedly decreased arterial oxygen saturations, widened alveolar-arterial oxygen gradients, and clinically debilitating dyspnea. We conclude that rejection may result in significant V/Q mismatch and hypoxemia in PPH patients undergoing SLT, which may limit the use of this specific type of surgery for PPH.

Pulmonary mechanics after cardio-pulmonary transplantation, an experimental study

An experimental model was developed in pigs (weight: 25 +/- 2 kg), to evaluate pulmonary mechanics during the first 2 h of reperfusion following heart-lung transplantation. We studied two groups with three transplantations each: group A (45 min of preservation) and group B (6 h of preservation). After rinsing out the heart-lung mass by the injection of a cold intracellular solution (K+ = 115 mEq/l) into the aorta and the pulmonary artery, the organs were removed and conserved in a cold environment (0.5 degrees C). The orthotopic heart-lung transplantation was carried out using extra-corporeal circulation. Pulmonary mechanics were evaluated before and after transplantation by measuring the pulmonary compliance (C), and the aero-dynamic resistance (R) with an interrupted air flow technique. [table: see text] The duration of ischaemia appeared to be a pernicious factor in cardiopulmonary function. In all cases, the protection protocol of the heart-lung block had allowed a cutting-off of the cardiorespiratory assistance. However, there were major pulmonary mechanical perturbations, associated with a reduction in the pulmonary compliance and a very important increase in the aerodynamic resistance.

Heart-lung transplantation in infants, children, and adolescents

We have performed heart-lung transplantation in 10 children for the preoperative diagnoses of primary pulmonary hypertension (4), complex congenital heart disease with pulmonary hypertension (4), pulmonary atresia (1), and cystic fibrosis (1). Ages ranged from 4 months to 18 years. There were 15 episodes of pulmonary rejection, with an occurrence rate of 1.67 episodes per patient. Pulmonary infections occurred frequently, with an occurrence rate of 3.3 episodes per patient. The actuarial survival rate at 1 and 2 years was 78% and 47%, respectively. Patient attrition between 1 and 2 years was attributable to the complications of obliterative bronchiolitis, which has effected 71% (5/7) of the long-term survivors. Four of the 5 surviving children have minimal physical limitation and are in functional class I. These data support continued investigation into heart-lung transplantation in children and set the stage for further program development into single-lung transplantation in children.

Pulmonary reflexes after human heart-lung transplantation

Heart-lung transplantation involves denervation of the lungs below the tracheal anastomosis, with associated permanent loss of all pulmonary innervation except post-ganglionic efferent nerves. This is supported by loss of the cough reflex to inhaled USNDW, which also implies that the RARs which mediate this cough mechanism lie in the central airways. Bronchoconstriction following inhalation of USNDW developed only in those HLT recipients with acute lung rejection; this was not related to methacholine responsiveness and may therefore represent a pathologic vascular response. Hyperresponsiveness to methacholine has been reported following HLT, which we found unrelated to inflammation or acute rejection. A similar hyperresponsiveness to histamine was seen, which correlated with the response to methacholine. This also implies that histamine may act directly on smooth muscle receptors, and not solely via a cholinergic reflex. Hyperresponsiveness following HLT may be due to development of a generalized denervation hypersensitivity. Bronchodilation following capsaicin inhalation has been observed in HLT recipients, and may be due to unopposed release of VIP from retained post-ganglionic efferent nerves.

Single lung transplantation for primary pulmonary hypertension

Single lung transplantation has become a therapeutic option for end-stage interstitial lung disease and obstructive lung disease. Our group recently extended this treatment to three patients with primary pulmonary hypertension. All patients had marked decreases in pulmonary artery pressures and pulmonary vascular resistance and increases in cardiac output following single lung transplantation. Spirometry, lung volumes, and diffusion capacity were not different in comparison to preoperative studies. Quantitative ventilation-perfusion scans revealed the majority of perfusion distributed to the transplanted lung, with ventilation approximately equally divided between the native and the transplanted lung. Despite ventilation-perfusion imbalance, there was no resting hypoxemia and there was no arterial oxygen desaturation with exercise. One patient expired on the 30th postoperative day due to cytomegalovirus infection of the lungs. In the remaining two patients, maximum exercise capacity following transplantation was near normal in one recipient and reduced in the second recipient. Of note, there was no evidence of ventilatory limitation or impaired oxygenation during exercise in these two recipients. Although an exaggerated exercise ventilatory response was present, this did not limit exercise performance. This report supports the use of single lung transplantation for the treatment of primary pulmonary hypertension.

Pulmonary denervation in humans. Effects on dyspnea and ventilatory pattern during exercise

The role of the pulmonary autonomic nerves in the mediation of respiratory sensation is unclear. Pulmonary neurogenic mechanisms may contribute to dyspnea either directly or indirectly via an influence on the pattern of ventilation. Using human heart-lung transplantation as a model of pulmonary denervation, we studied the ventilatory response, respiratory drive (P0.1), and sensation of breathlessness (modified Borg scale) during maximal incremental bicycle exercise. The subjects were four female heart-lung transplant recipients 3 to 9 months post-transplant and 10 age-matched control subjects. The ventilatory response to increasing CO2 output (VCO2) was higher (p less than 0.001) in transplant recipients than in control subjects, such that ventilation at peak exercise was similar in the two groups despite a lower peak VCO2 in transplant recipients. The ratio of tidal volume to inspiratory capacity increased with increasing ventilation in a similar fashion in both groups. Although the respiratory rate increased more quickly in transplant recipients, it was similar at peak ventilation in the two groups. Ventilatory timing and duty cycle at half-peak and peak ventilation were similar in transplant recipients and control subjects. Dyspnea ratings were not different between the two groups at similar levels of ventilation. Dyspnea as a function of P0.1 was also similar in transplant and control groups. These results indicate that pulmonary neurogenic mechanisms play a role in determining the level, but not the pattern, of ventilation during exercise. Furthermore, these pathways do not appear to contribute significantly to the perception of breathlessness in normal humans.

Pulmonary function after heart-lung transplantation using larger donor organs

Restrictive pulmonary function after heart-lung transplantation (HLT) has been attributed to the use of smaller donor lungs and/or an inability to generate normal negative pleural pressures. Pleural pressure generation depends on both the size of the recipient thoracic cage and its neuromuscular integrity. To determine whether lung volumes after heart-lung transplantation are more dependent on donor lung size or on recipient chest wall characteristics, seven HLT recipients were evaluated before and after transplantation. Postoperative values initially (average, 2 months), 6, and 12 months after transplantation were compared with predicted lung volumes for the recipient and donor organs. TLC dropped from a mean of 5.2 +/- 0.5 L preoperatively to 3.7 +/- 0.3 L (p less than 0.05) 2 months after HLT, but it improved with time and ultimately was not different from preoperative values. The predicted TLC of the HLT donor organs were significantly larger than those of the recipient's predicted TLC, with a mean of 6.9 +/- 0.4 versus 5.3 +/- 0.3 L (p less than 0.05). DLCO, arterial PO2, and PCO2 did not change after surgery. Within limits, larger donor lungs appear to adapt to the constraints of the recipient chest and may be used with clinical success, without apparent adverse effects.

Lung function associated with histologically diagnosed acute lung rejection and pulmonary infection in heart-lung transplant patients

A group of 34 heart-lung transplant patients were studied with serial pulmonary function measurements, chest radiographs, and transbronchial biopsies from the time of surgery. These investigations were carried out routinely at 3 and 6 months and then annually after transplantation as well as on clinical suspicion of acute lung rejection or infection. A total of 61 transbronchial biopsies and concurrent lung function and chest radiographs were obtained. Of the biopsies, 30 (49.2%) showed histologic evidence of lung rejection, 12 (19.7%) demonstrated various opportunistic infections, and 19 (31.1%) were normal. Compared to during episodes of normal biopsies, FEV1 decreased significantly with lung rejection (p less than 0.001) and with infection (p less than 0.01). Vital capacity (VC) and DLCO also fell with these acute lung complications. Using histologic diagnosis as a standard, lung function testing had a sensitivity of 86% in detecting lung rejection in the first 3 months postoperation and 75% in the subsequent period. Its sensitivity for detecting lung infection was 75%. Although not distinguishing between these two complications, lung function had a specificity of 84% for detecting occurrence of an acute lung complication. Chest radiographs, although of similar sensitivity in the first 3 months postsurgery, had a sensitivity of only 19% for rejection in subsequent months and 58% for infection. Its specificity was 100%. Lung function testing changes in a predictable fashion with lung rejection and infection, offers an improvement over chest radiographs, and provides a quantitative measurement to aid the decision of when to undertake transbronchial lung biopsy.

Bronchial responsiveness after human heart-lung transplantation

We evaluated bronchial responsiveness to inhaled albuterol (salbutamol), ipratropium bromide, methacholine, and propranolol in eight heart-lung transplant (HLT) recipients 2.3 +/- 1.5 months (mean +/- SD) (range, 1 to 4.5 months) after HLT. All patients had a restrictive ventilatory defect but none had airflow limitation (FEV1/FVC = 0.93 +/- 0.05) (range, 0.86 to 0.97). Specific airway conductance (sGaw) improved significantly with both albuterol (p less than 0.01) and ipratropium bromide (p less than 0.01) but FEV1 did not. Only one HLT patient had bronchoconstriction with propranolol, whereas all but one were hyperresponsive to methacholine. Prior inhalation of ipratropium bromide blocked the response to methacholine (p less than 0.005). Serial methacholine provocation tests performed in seven long-term survivors of HLT 24.6 +/- 16.0 months (range, 12 to 51 months) after HLT revealed no time-dependent evolution of bronchial hyperresponsiveness to methacholine. Limited maximal airway narrowing to methacholine was seen in five HLT recipients who showed a 29 +/- 4 percent (range, 23 to 35 percent) fall in FEV1 compared with two patients who did not achieve a plateau with a 47 percent and 63 percent fall in FEV1, respectively. These results further our understanding of bronchial responsiveness in the denervated transplanted lung. The findings of stable hyperresponsiveness to methacholine over a prolonged time interval, limited maximal airway narrowing to methacholine, and blockade of methacholine hyperresponsiveness by ipratropium bromide support the concept of denervation hypersensitivity of muscarinic receptors.

Cardiopulmonary exercise testing after single and double lung transplantation

The cardiopulmonary response to exercise was investigated in six single and six double lung transplant recipients using a three-minute incremental work rate protocol on a cycle ergometer. Maximum VO2 averaged 44.2 +/- 9.2 percent and 48.5 +/- 5.0 percent of predicted maximal VO2 in the single and double lung transplant groups, respectively. No evidence of ventilatory limitation to exercise was found in either group. Circulatory factors that may have limited exercise capacity included anemia and submaximal heart rates. There was a strong correlation between VO2/kg at venous blood lactate level of 2.2 mEq/L and vital capacity/body surface area in the single, but not in the double, lung recipients. Maximum VO2 in these lung transplant recipients was comparable to previously published values in heart-lung transplant recipients. The factors that limit maximum exercise capacity after lung transplantation deserve further study.

Surgical management of heart-lung transplantation

Using cyclosporin A, long-term survival after heart-lung transplantation became possible. The drug blocks the immune system more selectively and leaves the tracheal wound healing unimpaired. Since 1981, 501 clinical cases have been collected by the registry of the International Society for Heart Transplantation. Candidates for heart-lung transplantation reveal signs of irreversible heart and lung diseases that may have been caused by cardiac lesions (valvular diseases, Eisenmenger reaction due to congenital malformations) or by pulmonic disorders (primary pulmonary hypertension, emphysema, fibrosis). The standard surgical procedure, which combines donor and recipient tracheas, right atria, and aortas, makes three anastomoses necessary. Immunosuppressive regimen includes cyclosporin A (blood trough levels of 300 to 500 ng/mL), azathioprine (1 to 2 mg/kg), and rabbit antithymocyte globulin (1 to 4 mg immunoglobulin G/kg). After the first two postoperative weeks, rabbit antithymocyte globulin is replaced by methylprednisolone (0.3 to 0.1 mg/kg; 500 mg are given intravenously after opening the aortic cross-clamp; 3 x 125 mg on postoperative day 1). After heart-lung transplantation an extreme variety of problems may evolve. Early postoperative complications (within the first postoperative month) comprise acute isolated lung rejection, multiorgan failure, and bacterial pneumonia. Diagnosis of acute lung rejection proves difficult; it includes clinical signs, chest radiographic appearances, and cytoimmunological monitoring. Transbronchial lung biopsies are of similar value for precise diagnosis as are endomyocardial specimens after heart transplantation. Late postoperative complications (after 1 postoperative month) comprise viral pneumonia, fungal infection, tuberculosis, and chronic obliterative bronchiolitis.(ABSTRACT TRUNCATED AT 250 WORDS)

Reversible hyperinflation in emphysema

Pulmonary emphysema results in hyperinflation of the lungs and concomitant changes in the configuration of the thoracic cavity. We describe a patient who underwent bilateral lung transplantation for emphysema due to alpha 1 antitrypsin deficiency. Dramatic changes in chest dimensions and configuration occurred following transplantation, demonstrating the dynamic and reversible nature of the thoracic cavity abnormalities of emphysema.

Breathing during wakefulness and sleep after human heart-lung transplantation

To study the effects of pulmonary denervation on breathing during sleep, sleep studies were conducted on seven heart-lung transplant recipients (H-LT) and a comparable number of sex-matched normal subjects of similar age. Four of the H-LT patients had a restrictive pattern on spirometry. The time since transplantation ranged from 45 to 1,102 days. There were no significant differences between the groups with respect to total sleep time or distribution of sleep stages. There were no significant differences between the H-LT recipients and normal subjects with respect to baseline awake oxyhemoglobin saturation (SaO2) or the nadirs of SaO2 during REM and non-REM sleep, the absolute number and frequency (number per hour of sleep) of apneas, hypopneas, desaturation events, both over the whole night of study or separately during non-REM and REM sleep. Across wakefulness and all sleep stages, the H-LT patients tended to have shorter total respiratory cycle times (Ttot) (p = 0.052) and more rapid breathing frequency (F) than the normal subjects. This was associated with significantly shorter inspiratory times (Tl) (p less than 0.001) and smaller duty cycles (Tl/Ttot) (p less than 0.005) in the H-LT recipients. During non-REM and REM sleep, F tended to be higher in the H-LT recipients with pulmonary restriction than in the nonrestricted patients. There were no significant differences between the H-LT recipients and the normal subjects with regard to the periodicity of breathing, either in terms of timing parameters or breath amplitude.(ABSTRACT TRUNCATED AT 250 WORDS)

Lung rejection and bronchial hyperresponsiveness to methacholine and ultrasonically nebulized distilled water in heart-lung transplantation patients

Acute denervation of the lungs occurs after heart-lung transplantation (HLT), affecting both afferent and efferent nerves below the tracheal anastomosis. After surgery, the carina and main bronchi are perfused by mediastinal collaterals derived from the coronary arteries, and the intrapulmonary airways by retrograde blood flow from pulmonary artery collaterals. During acute rejection, the lungs are subjected to inflammation, particularly perivascular lymphocytic infiltrates. Rejection can be diagnosed by transbronchial biopsy (TBB). We report the bronchial responses to inhaled methacholine and ultrasonically nebulized distilled water (USNDW) in 16 HLT patients 2 wk to 43 months after surgery, relating them to the lung histopathology from concurrent TBB. Methacholine bronchial hyperresponsiveness was common, but it was not associated with airway epithelial or submucosal inflammation or perivascular lymphocytic infiltration. Six patients had a modest response to USNDW (fall in FEV1 greater than 10%). The responsiveness to USNDW was not associated with enhanced methacholine responsiveness or epithelial and mucosal inflammation. However, it was more commonly seen in patients with lung rejection and perivascular infiltrates. Methacholine hyperresponsiveness in HLT patients could therefore reflect denervation hypersensitivity of airway smooth muscle muscarinic receptors. The modest response to USNDW in some patients cannot be a result of a vagal reflex but could reflect a pathologic vascular response associated with lung rejection. These observations offer insight into the possible mechanisms of bronchial hyperresponsiveness in disease.

Ventilation and breathing pattern during progressive hypercapnia and hypoxia after human heart-lung transplantation

The effects of human pulmonary denervation on the ventilatory responses to progressive hyperoxic hypercapnia and isocapnic hypoxia as well as the effect on resting breathing pattern were evaluated in nine female heart-lung transplant (H-LT) recipients. The results were compared to those obtained from 10 normal women of comparable age and stature. Testing was performed 2 to 37 months after H-LT (median, 7.5 months). Cardiac function was normal in all H-LT recipients. None of the patients had spirometric evidence of airway obstruction, while six had a restrictive pattern with forced vital capacities less than 80% of predicted values. Resting minute ventilation (VE), tidal volume (VT), and ventilatory drive (VT/TI) in the H-LT recipients were not significantly different from those of the normal subjects. Inspiratory time (TI), however, was significantly shorter in the H-LT patients (1.64 +/- 0.2 versus 2.09 +/- 0.13 s, p = 0.035), and resting breathing frequency (F) tended to be greater in the H-LT recipients (16.27 +/- 2.04 versus 12.82 +/- 0.53 breaths/min, p = 0.052). The overall ventilatory response to hypercapnia was reduced after H-LT (0.91 +/- 0.17 versus 1.5 +/- 0.27 L/min/mm Hg CO2, p less than 0.043), as was the F response (0.2 +/- 0.09 versus 0.65 +/- 0.13 breaths/min/mm Hg CO2, p less than 0.01). The VT and VT/TI responses to hypercapnia did not differ between the H-LT recipients and normal subjects. There were no significant differences between the two groups with respect to the responses to progressive hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)

Ventilatory compensation for changes in posture after human heart-lung transplantation

We have studied the contribution of vagal pulmonary receptors to the stability of breathing during postural changes in humans. Quiet breathing was quantified in the seated and the supine postures in 10 patients with chronic pulmonary denervation due to heart-lung transplantation and 10 age and sex matched normal controls. In the vast majority of patients and normal subjects frequency histograms for tidal volume and mean inspiratory flow rate were virtually superimposed seated and supine. There were no significant differences in the mean levels of respiratory variables between postures in either group (except for mean inspiratory flow rate in the patients which was slightly greater seated than supine). Experiments performed on a tilt table in two additional patients showed that the ventilatory response to postural changes was immediate. In addition, the response was maintained after blockade of intact tracheal stretch receptors with aerosolized lidocaine. These results indicate that adequate ventilatory compensation during postural changes does not depend on vagal afferent information arising in intrapulmonary or tracheal airway stretch receptors. The appropriate receptors may be diaphragmatic Golgi tendon organs.

Bronchiolitis obliterans

Bronchiolitis obliterans in the adult patient is a relatively uncommon and vexing clinical entity. This confusion results because this pathologic finding occurs in a variety of diverse clinical settings. Bronchiolitis obliterans is a fibrotic process that primarily affects the small conducting airways. The lesion results from damage to the bronchiolar epithelium and the repair process leads to excessive proliferation of granulation tissue. The alveoli adjacent to the small airway are almost always involved; however, a considerable portion of the interstitium is usually spared. The findings in these patients may physiologically and radiographically mimic chronic obstructive pulmonary disease (COPD). On the other hand, some of the processes associated with bronchiolitis obliterans result in restrictive or mixed restrictive and obstructive ventilatory defects; consequently, they may be confused with other diffuse infiltrative lung disorders. This review will focus principally on bronchiolitis obliterans in adults, which, until recently, was considered rare. There has been heightened interest in this process in adults because of its association with the connective tissue diseases, its development following toxic fume exposure, its occurrence as a result of chronic graft versus host reactions, and the increasing recognition of patients with idiopathic forms of the disease that have an insidious onset often confused with more common problems such as COPD or idiopathic pulmonary fibrosis.

The pathology of combined heart-lung transplantation: an autopsy study

Clinical heart-lung transplantation (HLT) began at Stanford University (Stanford, CA) in 1981, and since then, over 40 HLTs have been performed. There is now a worldwide total of 250 HLTs. While much of the pathology that occurs in patients receiving an HLT is similar to that which develops in patients with other transplanted organ systems, these patients also develop unique clinical complications and pathologic processes that deserve emphasis. We report the autopsy findings of 20 HLT recipients, of whom 12 died in hospital one day to 4 months post-HLT. A major contributing factor in five of these postoperative deaths was pleural hemorrhage from adhesions due to prior chest surgery. Overwhelming viral and fungal infections accounted for six deaths. The seventh patient died as a result of adult respiratory distress syndrome (ARDS). Two patients showed histologic evidence of the reimplantation response. Six long-term survivors died (mean survival, 22 months) with obliterative bronchiolitis (OB). In four patients, OB was the immediate cause of death, while one patient died of an intercurrent myocardial infarct, and the other patient died of complications from an appendectomy. Two long-term survivors died without OB, one of iatrogenic causes at 63 months and the second due to unexplained ARDS at 52 months. Both patients without OB had virtually normal underlying pulmonary parenchyma. All of the long-term survivors had either coronary arterial or pulmonary vascular intimal sclerosis, and renal lesions attributable to cyclosporine A toxicity. Although histologic features of mild acute pulmonary and cardiac rejection were observed in four patients overall, these did not contribute to the cause of death in any case. Although OB is a major threat to its success, HLT is a viable option for patients with endstage pulmonary disease.

Evidence of an altered pattern of breathing during exercise in recipients of heart-lung transplants

Recipients of heart-lung transplants represent an unusual opportunity to study the regulation of ventilation, because the neural pathways between the lungs and the central nervous system are disrupted in these patients. We compared the ventilation response in seven recipients of heart-lung transplants who had normal pulmonary function and seven recipients of heart transplants, all of whom performed incremental bicycle ergometry. The level of ventilation in recipients of heart-lung transplants was similar to that in heart-transplant recipients for equivalent levels of carbon dioxide production. Arterial pH and partial pressure of carbon dioxide at maximal exercise were normal and not significantly different in the two groups, also suggesting that levels of ventilation were appropriate in both groups. However, the rate of the rise in respiratory rate for increasing levels of ventilation was significantly lower in recipients of heart-lung transplants than in heart-transplant recipients, and the initial increase in tidal volume was more rapid in the former group than in the latter. Thus, recipients of heart-lung transplants have an appropriate level of ventilation during exercise as the result of a disproportionate increase in tidal volume at a reduced respiratory rate. We speculate that intrapulmonary receptors are important in regulating the pattern, but not the absolute level, of ventilation during exercise.

Elastic behavior of the transplanted lung. Exponential analysis of static pressure-volume relationships

We compared indices of muscle strength, parameters of mechanical lung function, and static pressure-volume curves in 12 heart-lung transplant (HLT) recipients to determine whether observed restrictive ventilatory defects represented abnormal elastic behavior of the transplanted lungs. Pressure-volume curves were analyzed using an exponential equation to generate the shape constant K, which describes the nonlinear behavior of pressure-volume relationships over a substantial range. For the group, K was 91% predicted, implying that there was not a diffuse abnormality of elastic properties of the transplanted lungs despite a mean TLC of 80% predicted. However, the mean maximal transpulmonary pressure (PLmax) was significantly low at 23.4 cm H2O (61% predicted) possibly related to the effects of surgery on thoracic cage mobility, but also in keeping with a reduction in power and efficiency of the thoracic musculature. The ability to achieve predicted TLC post-HLT was related to the preservation of optimal inspiratory force as TLC (% predicted) was highly correlated with maximal inspiratory pressure (PImax) (% predicted) (r = 0.83) (p less than 0.001). The ratio (TLC post-HLT)/(TLC pre-HLT) was 1.00 +/- 0.18 (r = 0.82) (p less than 0.005), suggesting donor organs were well matched to recipient chest cavities, but also emphasizing that the recipients had a low TLC prior to HLT. We conclude that the presence of a stable restrictive defect post-HLT is determined primarily by the volumetric constraints of the recipient chest cavity and within these constraints by the strength and efficiency of the thoracic musculature rather than a diffuse intrinsic abnormality of pulmonary elastic properties as a consequence of the transplantation process.

Cardiopulmonary function at maximum tolerable constant work rate exercise following human heart-lung transplantation

Studies were performed measuring parameters of respiratory and circulatory function at rest and during maximum tolerable constant work rate treadmill exercise in 16 clinically well patients who had undergone heart-lung transplantation for end stage pulmonary hypertension. Ten patients were studied before and within eight weeks following transplantation. Long-term function with exercise was further evaluated with follow up studies at one year (n = 10) and two years (n = 6), posttransplantation. Posttransplant gas exchange and ventilation during exercise are essentially normal with neither being limiting to maximal exercise. Exercise capacity is significantly improved posttransplant, primarily as a result of improvement in the circulation over that found pretransplant in uncorrected pulmonary hypertension. Although improved, circulatory limitations of maximal exercise may still persist. Cardiorespiratory function at maximum tolerable exercise is well maintained following heart-lung transplantation for at least two years, providing no complications occur. This suggests that denervation of the heart and lungs, disruption of the bronchial circulation and pulmonary lymphatics, and the graft ischemia encountered at the time of transplantation impose no serious limitations on long-term cardiopulmonary function. The overall functional capacities of the transplanted heart and lungs are more than adequate for meeting the activities of normal life.

Heart and lung transplantation in patients with end stage lung disease

Combined heart and lung transplantation was used to treat seven patients with end stage lung disease. All were severely disabled, and their disease carried a poor prognosis. Six patients were well four to 33 months after transplantation. One patient died after 44 days from a primary cytomegalovirus pneumonia transmitted from the donor. All the survivors had normal exercise tolerance and greatly improved lung function. It is concluded that heart and lung transplantation is a suitable treatment for selected patients with end stage chronic lung disease.

Comparison of progressive exercise performance of normal subjects and patients with primary pulmonary hypertension

The extent of exercise limitation and the mechanisms for that limitation in 11 patients with primary pulmonary hypertension (PPH) were studied by progressive, upright cycle ergometry. All patients had a mean pulmonary artery pressure of 30 mm Hg or higher (mean, 56 +/- 15), normal pulmonary function testing, normal pulmonary capillary wedge pressure, and pulmonary angiography consistent with the diagnosis. Rest and exercise data obtained from the patients with PPh were compared with data obtained from 11 matched, sedentary control subjects. Mean maximal oxygen consumption (VO2) was 13 +/- 4 ml/kg/min in the PPH group compared with 28 +/- 7 ml/kg/min in the controls. At maximal VO2 the minute ventilation (VE) was similar; however, the VE at any level of carbon dioxide production (VCO2) during rest and exercise was significantly higher in the PPH group. Maximal heart rate and oxygen pulse (VO2/heart rate) was significantly higher in the control group (148 +/- 18 vs 180 +/- 24, and 6.3 +/- 2.2 vs 9.9 +/- 3.9, respectively). Anaerobic threshold occurred earlier during progressive exercise in the PPH group and correlated positively with the maximal oxygen pulse achieved in patients with PPH. In conclusion, patients with PPH have severe exertional limitation due to cardiovascular factors with an inability to maintain appropriate oxygen delivery to the body during exercise. No respiratory impairment was recognized; however, an exaggerated ventilatory response to exercise at any level of VCO2 was found.

Anaesthesia for combined heart and lung transplantation

In December 1983, Harefield Hospital started a programme for combined heart and lung transplantation. Fifty-two transplants have been successfully performed, with 36 survivors (April 1986). Patient selection and anaesthetic management of both donor and recipient are discussed. Two case histories are presented which illustrate the principles of anaesthetic management and postoperative care.

Pulmonary function in advanced pulmonary hypertension

Pulmonary mechanical function and gas exchange were studied in 33 patients with advanced pulmonary vascular disease, resulting from primary pulmonary hypertension in 18 cases and from Eisenmenger physiology in 15 cases. Evidence of airway obstruction was found in most patients. In addition, mean total lung capacity (TLC) was only 81.5% of predicted and 27% of our subjects had values of TLC less than one standard deviation below the mean predicted value. The mean value for transfer factor (TLCO) was 71.8% of predicted and appreciable arterial hypoxaemia was present, which was disproportionate to the mild derangements in pulmonary mechanics. Patients with Eisenmenger physiology had significantly lower values of arterial oxygen tension (PaO2) (p less than 0.05) and of maximum mid expiratory flow (p less than 0.05) and significantly higher pulmonary arterial pressure (p less than 0.05) than those with primary pulmonary hypertension, but no other variables were significantly different between the two subpopulations. It is concluded that advanced pulmonary vascular disease in patients with primary pulmonary hypertension and Eisenmenger physiology is associated not only with severe hypoxaemia but also with altered pulmonary mechanical function.

Replacement of the failing heart

Heart transplantation is an effective means of treating patients with severe congestive heart failure. Following heart transplantation, the 1-year survival rate is now greater than 80%, and the 5-year survival rate is more than 60% at major medical centers. More than 1,200 heart transplants were performed in more than nine countries worldwide in 1985. The failure of medicare to pay for this procedure is no longer defensible on medical grounds. The argument in favor of medicare funding for heart transplantation is at least as compelling as that for kidney dialysis, the treatment of cancer, or AIDS. The limited availability of donor organs (at most, 1300-2000/year) is likely to place a finite constraint on the number of heart transplants that can and will be performed. Although combined heart-lung transplantation is feasible therapy for certain patients with severe pulmonary hypertension, the availability of suitable donors poses an even greater restriction on this procedure. Totally implantable ventricular assist devices are on the horizon. These devices have the potential for helping 17,000 to 35,000 patients annually at an estimated cost to society of $2.5 to $5 billion per annum. The development and use of such extremely expensive technology poses major socioeconomic and ethical questions for society.

Cardiopulmonary transplantation

Heart-lung transplantation is now an established clinical procedure. Immediate problems include satisfactory donor procurement and the control of hemostasis in patients who have had extensive previous surgery. Immediate return of normal pulmonary function is good but is not maintained in all patients. Late dyspnea has occurred in some patients, one of whom had a successful retransplant procedure. Progress is now being made in the early detection and management of late pulmonary rejection, which are likely to improve late symptomatic results and survival.