EXERCISE LIMITATION FOLLOWING EXTENSIVE PULMONARY RESECTION

Case Studies in Physiology: Cardiopulmonary exercise testing and inspiratory muscle training in a 59-year-old, four years after an extra-pleural pneumonectomy

This case report characterizes the physiological responses to incremental cycling and determines the effects of 12 weeks of inspiratory muscle training (IMT) on respiratory muscle strength, exercise capacity and dyspnea in a physically active 59-year-old female, four years after a left-sided extra-pleural pneumonectomy (EPP). On separate days, a symptom limited incremental exercise test and a constant work rate (CWR) test at 75% of peak work rate (WR) were completed, followed by 12 weeks of IMT and another CWR test. IMT consisted of two sessions of 30 repetitions twice daily for 5 days per week. Physiological and perceptual variables were measured throughout each exercise test. The participant had a total lung capacity that was 43% predicted post-EPP. A rapid and shallow breathing pattern was adopted throughout exercise, and the ratio of minute ventilation to carbon dioxide output was elevated for a given work rate. Oxygen uptake was 74%predicted and WR was 88%predicted. Following IMT, maximal inspiratory pressure improved by 36% (-27.1 cmH₂O) and endurance time by 31s, with no observable changes in any submaximal or peak cardiorespiratory variables during exercise. The intensity and unpleasantness of dyspnea increased by 2 and 3 Borg 0-10 units, respectively, at the highest equivalent submaximal exercise time achieved on both tests. Despite having undergone a significant reduction in lung volume post-EPP, the participant achieved a relatively normal peak incremental WR, which may reflect a high level of physical conditioning. This case report also demonstrates that IMT can effectively increase respiratory muscle strength several years following EPP.

Defining a stimuli-response relationship in compensatory lung growth following major resection

Major lung resection is a robust model that mimics the consequences of loss-of-functioning lung units. We previously observed in adult canines, following 42% and 58% lung resection, a critical threshold of stimuli intensity for the initiation of compensatory lung growth. To define the range and limits of this stimuli-response relationship, we performed morphometric analysis on the remaining lobes of adult dogs, 2-3 years after surgical removal of ∼ 70% of lung units in the presence or absence of mediastinal shift. Results were expressed as ratios to that in corresponding control lobes. Lobar expansion and extravascular tissue growth (∼ 3.8- and ∼ 2.0-fold of normal, respectively) were heterogeneous; the lobes remaining next to the diaphragm exhibited a greater response. Tissue growth and capillary formation, indexed by double-capillary profiles, increased, regardless of mediastinal shift. Septal collagen fibers increased up to 2.7-fold, suggesting a greater need for structural support. Compared with previous cohorts following less-extensive resection, tissue volume and gas-exchange surface areas increased significantly only in the infracardiac lobe following 42% resection, exceeded two- to threefold in all lobes following 58% resection, and then exhibited diminished gains following ∼ 70% resection. In contrast, alveolar-capillary formation increased with incremental resection without reaching an upper limit. Overall structural regrowth was most vigorous and uniform following 58% resection. The diminishment of gains in tissue growth, following ∼ 70% resection, could reflect excessive or maldistributed mechanical stress that threatens septal integrity. Results also suggest additional independent stimuli of alveolar-capillary formation, possibly related to the postresection augmentation of regional perfusion.

Unilateral absence of pulmonary artery in children: bronchovascular anatomy, natural course and effect of treatment on lung growth

BACKGROUND

Unilateral absence of pulmonary artery (UAPA) is a rare congenital anomaly with few published studies focusing on anatomy and outcome.

OBJECTIVE

To assess the bronchovascular anatomy, lung volume and growth in treated and untreated patients with UAPA.

MATERIALS AND METHODS

Eighteen children with UAPA (isolated: n = 12; associated with congenital heart disease: n = 6) were retrospectively studied to assess the vascularization and lung segmentation and to appraise lung volume evolution in treated and untreated patients. Age at presentation: 1 day to 6 years; mean follow-up duration 13.6 years. Reperfusion of the affected pulmonary artery was attempted in 10 children (younger than 6 months: n = 7; older than 6 months: n = 3).

RESULTS

Bronchovascular lung segmentation was complete in all cases. In children treated before 6 months of age, lung volume normalized in 3 and remained normal in 3, and hypoplasia progression was noted in 1. Hypoplasia persisted in children treated after 6 months of age. In untreated children, lung hypoplasia was unchanged in cases diagnosed after 7 months of age (n = 4) and progressive in cases diagnosed before 3 months (n = 4).

CONCLUSION

In UAPA, lung anatomy and volume are normal at birth. Revascularization of the affected pulmonary artery before 6 months of age seems to allow optimal lung growth and prevent postnatal lung hypoplasia and development of collaterals.

Physical activity and lung cancer survivorship

A lung cancer diagnosis and associated therapeutic management is associated with unique and varying degrees of adverse physical/functional impairments that dramatically reduce a patient's ability to tolerate exercise. Poor exercise tolerance predisposes to increased susceptibility to other common age-related diseases, poor quality of life (QOL), and likely premature death. Here we review the putative literature investigating the role of exercise as an adjunct therapy across the lung cancer continuum (i.e., diagnosis to palliation). The current evidence suggests that exercise training is a safe and feasible adjunct therapy for operable lung cancer patients both before and after pulmonary resection. Among patients with inoperable disease, feasibility and safety studies of carefully prescribed exercise training are warranted. Preliminary evidence in this area supports that exercise therapy may be an important consideration in multidisciplinary management of patients diagnosed with lung cancer.

Adjustments in cardiorespiratory function after pneumonectomy: results of the pneumonectomy project

OBJECTIVE

To assess lung function, gas exchange, exercise capacity, and right-sided heart hemodynamics, including pulmonary artery pressure, in patients long term after pneumonectomy.

METHODS

Among 523 consecutive patients who underwent pneumonectomy for lung cancer between January 1992 and September 2001, 117 were alive in 2006 and 100 were included in the study. During a 1-day period, each patient had complete medical history, chest radiographs, pulmonary function studies, resting arterial blood gas analysis, 6-minute walk test, and Doppler echocardiography.

RESULTS

Most patients (N = 73) had no or only minimal dyspnea. On the basis of predicted values, functional losses in forced expiratory volume in 1 second and forced vital capacity were 38% ± 18% and 31% ± 24%, respectively, and carbon monoxide diffusing capacity decreased by 31% ± 18%. There was a significant correlation between preoperative and postoperative forced expiratory volume in 1 second (P < .01), and more hyperinflation was associated with better lung function (P < .01 for forced expiratory volume in 1 second). Gas exchange was normal at rest (Pao(2) = 88 ± 10 mm Hg; Paco(2) = 42 ± 3 mm Hg), and exercise tolerance (6-minute walk) was also normal (83% ± 17% of predicted values). Thirty-two patients had some degree of pulmonary hypertension, but in most of those cases, it was mild to moderate (mean systolic pressure of 36 ± 9 mm Hg) and not associated with significant differences in lung function (P = .57 for forced expiratory volume in 1 second), gas exchange (P = .08), and exercise capacity (P = .66).

CONCLUSIONS

These findings indicate that despite worsening of lung function by approximately 30% after pneumonectomy, most patients can adjust to living with only 1 lung. Pulmonary hypertension is uncommon and in most cases only mild to moderate.

Peak oxygen consumption and long-term all-cause mortality in nonsmall cell lung cancer

BACKGROUND

Identifying strong markers of prognosis is critical to optimize treatment and survival outcomes in patients with nonsmall cell lung cancer (NSCLC). The authors investigated the prognostic significance of preoperative cardiorespiratory fitness (peak oxygen consumption [VO(2peak)]) among operable candidates with NSCLC.

METHODS

By using a prospective design, 398 patients with potentially resectable NSCLC enrolled in Cancer and Leukemia Group B 9238 were recruited between 1993 and 1998. Participants performed a cardiopulmonary exercise test to assess VO(2peak) and were observed until death or June 2008. Cox proportional models were used to estimate the risk of all-cause mortality according to cardiorespiratory fitness category defined by VO(2peak) tertiles (<0.96 of 0.96-1.29/>1.29 L/min⁻¹) with adjustment for age, sex, and performance status.

RESULTS

Median follow-up was 30.8 months; 294 deaths were reported during this period. Compared with patients achieving a VO(2peak) <0.96 L/min⁻¹, the adjusted hazard ratio (HR) for all-cause mortality was 0.64 (95% confidence interval [CI], 0.46-0.88) for a VO(2peak) of 0.96 to 1.29 L/min⁻¹, and 0.56 (95% CI, 0.39-0.80) for a VO(2peak) of >1.29 L/min⁻¹) (P(trend) = .0037). The corresponding HRs for resected patients were 0.66 (95% CI, 0.46-0.95) and 0.59 (95% CI, 0.40-0.89) relative to the lowest VO(2peak) category (P(trend) = .0247), respectively. For nonresected patients, the HRs were 0.78 (95% CI, 0.34-1.79) and 0.39 (95% CI, 0.16-0.94) relative to the lowest category (P(trend) = .0278).

CONCLUSIONS

VO(2peak) is a strong independent predictor of survival in NSCLC that may complement traditional markers of prognosis to improve risk stratification and prognostication.

The lung cancer exercise training study: a randomized trial of aerobic training, resistance training, or both in postsurgical lung cancer patients: rationale and design

Background

The Lung Cancer Exercise Training Study (LUNGEVITY) is a randomized trial to investigate the efficacy of different types of exercise training on cardiorespiratory fitness (VO_2peak), patient-reported outcomes, and the organ components that govern VO_2peak in post-operative non-small cell lung cancer (NSCLC) patients.

Methods/Design

Using a single-center, randomized design, 160 subjects (40 patients/study arm) with histologically confirmed stage I-IIIA NSCLC following curative-intent complete surgical resection at Duke University Medical Center (DUMC) will be potentially eligible for this trial. Following baseline assessments, eligible participants will be randomly assigned to one of four conditions: (1) aerobic training alone, (2) resistance training alone, (3) the combination of aerobic and resistance training, or (4) attention-control (progressive stretching). The ultimate goal for all exercise training groups will be 3 supervised exercise sessions per week an intensity above 70% of the individually determined VO_2peak for aerobic training and an intensity between 60 and 80% of one-repetition maximum for resistance training, for 30-45 minutes/session. Progressive stretching will be matched to the exercise groups in terms of program length (i.e., 16 weeks), social interaction (participants will receive one-on-one instruction), and duration (30-45 mins/session). The primary study endpoint is VO_2peak. Secondary endpoints include: patient-reported outcomes (PROs) (e.g., quality of life, fatigue, depression, etc.) and organ components of the oxygen cascade (i.e., pulmonary function, cardiac function, skeletal muscle function). All endpoints will be assessed at baseline and postintervention (16 weeks). Substudies will include genetic studies regarding individual responses to an exercise stimulus, theoretical determinants of exercise adherence, examination of the psychological mediators of the exercise - PRO relationship, and exercise-induced changes in gene expression.

Discussion

VO_2peak is becoming increasingly recognized as an outcome of major importance in NSCLC. LUNGEVITY will identify the optimal form of exercise training for NSCLC survivors as well as provide insight into the physiological mechanisms underlying this effect. Overall, this study will contribute to the establishment of clinical exercise therapy rehabilitation guidelines for patients across the entire NSCLC continuum.

Trial Registration

NCT00018255

Exercise intolerance in cancer and the role of exercise therapy to reverse dysfunction

Exercise tolerance reflects the integrative capacity of components in the oxygen cascade to supply adequate oxygen for ATP resynthesis. Conventional cancer therapies can simultaneously affect one or more components of this cascade and reduce the body's ability to deliver or utilise oxygen and substrate, leading to exercise intolerance. We propose that molecularly-targeted therapy is associated with a further, more subtle, negative effect on the components that regulate exercise limitation. We outline possible causes of exercise intolerance in patients with cancer and the role of exercise therapy to mitigate or prevent dysfunction. We also discuss possible implications for exercise-regulated gene expression for cancer biology and treatment efficacy. A better understanding of these issues might lead to more effective integration of exercise therapy to optimise the treatment and management of patients with cancer.

Safety and feasibility of aerobic training on cardiopulmonary function and quality of life in postsurgical nonsmall cell lung cancer patients: a pilot study

BACKGROUND

A feasibility study examining the effects of supervised aerobic exercise training on cardiopulmonary and quality of life (QOL) endpoints among postsurgical nonsmall cell lung cancer (NSCLC) patients was conducted.

METHODS

Using a single-group design, 20 patients with stage I-IIIB NSCLC performed 3 aerobic cycle ergometry sessions per week at 60% to 100% of peak workload for 14 weeks. Peak oxygen consumption (VO(2peak)) was assessed using an incremental exercise test. QOL and fatigue were assessed using the Functional Assessment of Cancer Therapy-Lung (FACT-L) scale.

RESULTS

Nineteen patients completed the study. Intention-to-treat analysis indicated that VO(2peak) increased 1.1 mL/kg(-1)/min(-1) (95% confidence interval [CI], -0.3-2.5; P = .109) and peak workload increased 9 W (95% CI, 3-14; P = .003), whereas FACT-L increased 10 points (95% CI, -1-22; P = .071) and fatigue decreased 7 points (95% CI; -1 to -17; P = .029) from baseline to postintervention. Per protocol analyses indicated greater improvements in cardiopulmonary and QOL endpoints among patients not receiving adjuvant chemotherapy.

CONCLUSIONS

This pilot study provided proof of principle that supervised aerobic training is safe and feasible for postsurgical NSCLC patients. Aerobic exercise training is also associated with significant improvements in QOL and select cardiopulmonary endpoints, particularly among patients not receiving chemotherapy. Larger randomized trials are warranted.

Shifting sources of functional limitation following extensive (70%) lung resection

We previously found that, following surgical resection of approximately 58% of lung units by right pneumonectomy (PNX) in adult canines, oxygen-diffusing capacity (Dl(O(2))) fell sufficiently to become a major factor limiting exercise capacity, although the decline was mitigated by recruitment, remodeling, and growth of the remaining lung units. To determine whether an upper limit of compensation is reached following the loss of even more lung units, we measured pulmonary gas exchange, hemodynamics, and ventilatory power requirements in adult canines during treadmill exercise following two-stage resection of approximately 70% of lung units in the presence or absence of mediastinal distortion. Results were compared with that in control animals following right PNX or thoracotomy without resection (Sham). Following 70% lung resection, peak O(2) uptake was 45% below normal. Ventilation-perfusion mismatch developed, and pulmonary arterial pressure and ventilatory power requirements became markedly elevated. In contrast, the relationship of Dl(O(2)) to cardiac output remained normal, indicating preservation of Dl(O(2))-to-cardiac output ratio and alveolar-capillary recruitment up to peak exercise. The impairment in airway and vascular function exceeded the impairment in gas exchange and imposed the major limitation to exercise following 70% resection. Mediastinal distortion further reduced air and blood flow conductance, resulting in CO(2) retention. Results suggest that adaptation of extra-acinar airways and blood vessels lagged behind that of acinar tissue. As more lung units were lost, functional compensation became limited by the disproportionately reduced convective conductance rather than by alveolar diffusion disequilibrium.

Cardiac Function and Position More Than 5 Years After Pneumonectomy

BACKGROUND

Pneumonectomy not only reduces the pulmonary vascular bed but also changes the position of the heart and large vessels, which may affect the function of the heart. We investigated long-term effects of pneumonectomy on right ventricular (RV) and left ventricular (LV) function and whether this function is influenced by the side of pneumonectomy or the migration of the heart to its new position.

METHODS

In 15 patients who underwent pneumonectomy and survived for more than 5 years, we evaluated by dynamic magnetic resonance imaging the function of the RV and LV and the position of the heart within the thorax.

RESULTS

Long-term effect of pneumonectomy on the position of the heart is characterized by a lateral shift after right-sided pneumonectomy and rotation of the heart after left-sided pneumonectomy. Postoperatively, heart rate was high (p = 0.006) and stroke volume was low (p = 0.001), compared with the reference values, indicating impaired cardiac function. Patients after right-sided pneumonectomy had an abnormal low RV end-diastolic volume of 99 +/- 29 mL together with a normal LV function. No signs of RV hypertrophy were found. In left-sided pneumonectomy patients, RV volumes were normal whereas LV ejection fraction was abnormally low.

CONCLUSIONS

The long-term effects of pneumonectomy on the position of the heart are characterized by a lateral shift in patients after right-sided pneumonectomy and rotation of the heart in patients after left-sided pneumonectomy. Overall, cardiac function in long-term survivors after pneumonectomy is compromised, and might be explained by the altered position of the heart.

Pulmonary artery pressure and blood flow as predictors of outcome from lung cancer resection

OBJECTIVE

Pulmonary hypertension is a putative risk factor for lung resection but catheter measurements are invasive. The aim of the present study was to assess prediction of mortality and complications from lung resection by Doppler echocardiographic estimates of pulmonary artery pressure (PAp) and soluble gas uptake estimates of effective pulmonary blood flow (Q(RB)).

METHODOLOGY

In 33 lung cancer patients, resting PAp (sys) and Q(RB) were measured preoperatively. In 13 patients, supine exercise estimates of PAp (sys) were also made and in five patients catheter PAp estimates were made.

RESULTS

Baseline PAp (sys) was 35 +/- 5 mmHg in four patients who died and 35 +/- 5 mmHg in 27 survivors. Post-exercise PAp (sys) was 58 +/- 11 mmHg in non-survivors and 60 +/- 11 mmHg in survivors (both not significant). Resting Q(RB) was 3.9 +/- 0.35 L/min in two non-survivors compared with 4.7 +/- 0.90 L/min in 22 survivors (P = 0.12) and was significantly lower in those experiencing complications. Regression analysis showed no significant relationship between resting or post-exercise PAp and mortality, although low Q(RB) tended towards predicting mortality (P = 0.07). There were also trends for higher PAp (sys) to predict respiratory and cardiac complications (P = 0.08) and for lower Q(RB) to predict unspecified or surgical complications.

CONCLUSION

PAp and Q(RB) did not predict outcome from lung resection better than baseline respiratory function indices.

Functional evaluation before lung resection

Advances in operative technique and perioperative care have reduced surgical morbidity and mortality considerably after pulmonary resections. Various single and combined parameters of functional operability have been proposed to assess the surgical risk. Patients with normal or only slightly impaired pulmonary function (FEV1 and DLCO > or = 80% predicted) and no cardiovascular risk factors can undergo pulmonary resections up to a pneumonectomy without further investigation. For others, exercise testing, pulmonary split-function studies, or a combination of these methods are recommended. Cardiopulmonary exercise testing, most frequently performed as a symptom-limited test with the measurement of VO2max, assesses the pulmonary and cardiovascular reserves. A VO2max of less than 10 mL/kg/minute generally is considered prohibitive for any resection, a value of greater than 20 mL/kg/minute or greater than 75% predicted normal, safe for major resections. Split-function studies are radionuclide-based estimations of the ppo values of various parameters. The currently used ppo parameters are FEV1-ppo, DLCO-ppo, and VO2max-ppo. Suggested cutoff values for safe resection are: FEV1-ppo and DLCO-ppo 40% or greater than predicted, and V(r)O2max-ppo 35% or greater than predicted, combined with an absolute value of greater than or equal to 10 mL/kg/minute. The lowest acceptable ppo values remain to be confirmed by additional prospective studies. Resections involving not more than one lobe usually lead to an early functional deficit followed by recovery. The permanent loss in pulmonary function is small (approximately 10%) and exercise capacity is reduced only slightly or not at all. Pneumonectomy leads to an early permanent loss of about 33% in pulmonary function and approximately 20% in exercise capacity. Pulmonary function tests alone therefore overestimate the functional loss after lung resection.

Exercise capacity of thoracotomy patients in the early postoperative period

OBJECTIVE

We investigated the mechanism involved with the initial drop and subsequent recovery of exercise capacity in the early postoperative period of thoracotomy patients.

METHODS

Sixteen patients (13 who had undergone lobectomy, 3 who had undergone pneumonectomy) underwent a routine pulmonary function test (PFT) and a cardiopulmonary exercise test preoperatively, within 14 postoperative days (POD; post-1; mean +/- SD, 9 +/- 2 POD), and after 14 POD (post-2; mean, 26 +/- 12 POD).

RESULTS

After surgery on post-1, PFT results of FVC, FEV(1), and maximum ventilatory volume (MVV) significantly decreased. Oxygen uptake (VO(2)) at a venous blood lactate level of 2.2 mmol/L (La-2. 2), which was adopted as the empirical anaerobic threshold, and maximum V O(2) (VO(2)max) decreased significantly to 88.2 +/- 7.9% and 73.1 +/- 15.4% of the preoperative values, respectively. La-2.2 min ventilation (VE)/ MVV and maximum VEmax)/MVV increased significantly from 0.36 +/- 0.08 to 0. 66 +/- 0.20 and from 0.58 +/- 0.14 to 0.80 +/- 0.09, respectively. On post-2, though La-2.2 VO(2) did not change, VO(2)max improved significantly to 81.5 +/- 19.7% of the preoperative values, in association with significant increases in maximal tidal volume and VEmax, which were produced by significant increases in the PFT results. La-2.2 VE/MVV also decreased significantly to 0.49 +/- 0.13, which indicated a sufficient recovery of respiratory reserve at submaximal exercise.

CONCLUSIONS

The initial drop of exercise capacity after lung resection seems to be derived from both circulatory and ventilatory limitations. Further, the subsequent recovery within 1 month seems to be produced by an improvement in ventilatory limitation, which was caused by the surgical injury to the chest wall.

Longterm effects of pulmonary resection on cardiopulmonary function

BACKGROUND

Major lung resection decreases ventilatory capacity and reduces exercise tolerance, impairing postoperative quality of life. But we have often seen respiratory symptoms improve during several years of postoperative followup. In the current study, we evaluated postoperative changes in cardiopulmonary function on exertion of patients with lung cancer surviving for more than three years, and the corresponding changes of their respiratory symptoms.

METHODS

The effects of pulmonary resection on cardiopulmonary function were evaluated in eight patients with lung cancer. Pulmonary function tests and hemodynamic study at rest and during exercise were performed before, in the early (4 to 6 months) and late (42 to 48 months) postoperative phases after major lung resection.

RESULTS

None of the eight patients had any remarkable symptoms before lung resection. In the early postoperative study, the general condition of five patients deteriorated compared with their preoperative status. In the late postoperative study, four patients showed an improvement of their daily activities from the early postoperative phase. Pulmonary function in the late postoperative phase did not show major changes except for airway resistance and percentage of carbon monoxide diffusing capacity as compared with the early phase, which showed deterioration as compared with the preoperative period. Cardiac index and stroke volume index were significantly decreased during exercise on maximal effort in the late postoperative phase compared with other phases. These results suggest that the peak blood flow per unit of remaining lung during exercise becomes lower with time after lung resection, indicating deterioration of the condition of the pulmonary vascular bed. The deterioration was also revealed from the pressure-flow curve.

CONCLUSIONS

The condition of the pulmonary vascular bed after major lung resection does not improve, even in the late postoperative phase, although clinical symptoms were sometimes improved compared with the early postoperative period.

Cardiopulmonary limitations to exercise in restrictive lung disease

Cardiopulmonary limitations to exercise in restrictive lung disease. Med. Sci. Sports Exerc., Vol. 31, No. 1 (Suppl.), pp. S28-S32, 1999. Restrictive lung disease encompasses a large and diverse group of disorders characterized by a diminished lung volume. These disorders exhibit common pathophysiologic features including abnormal gas exchange caused by loss of functioning alveolar-capillary unit, abnormal respiratory muscle energetics caused by altered mechanical ventilatory function, and secondary hemodynamic and cardiac dysfunction. Impaired gas exchange is the most prominent exercise abnormality in interstitial lung disease and eventually develops in other causes of lung restriction as well. Measurements of diffusing capacity (DLCO) and alveolar-arterial oxygen tension gradient during exercise are more sensitive detectors of disease than measurements at rest. Excessive dead space ventilation is common in pulmonary parenchymal, pleural, and thoracic diseases, leading to a higher minute ventilation and ventilatory work during exercise. The associated increase in the metabolic energy requirement of respiratory muscles may exceed 50% of available total body oxygen delivery and result in insufficient energy delivery to nonrespiratory muscles that sustain locomotion. Pulmonary arterial hypertension develops secondarily to an increased pulmonary vascular resistance. In addition, diastolic filling of the ventricles during exercise may be restricted by pulmonary fibrosis or anatomical restriction of the pleura and thorax, contributing to secondary cardiac dysfunction. Examples of heart-lung interaction are illustrated by the patient after unilateral pneumonectomy. These pathophysiologic changes help explain why functional disability in these patients is often out proportion to the impairment in lung function.

Recovery and limitation of exercise capacity after lung resection for lung cancer

OBJECTIVE

To assess the effects of pulmonary resection for lung cancer on postoperative recovery and limitation of exercise capacity.

METHODS

Eighty-two patients (20 pneumonectomies, 62 lobectomies) underwent spirometric pulmonary tests and exercise capacity tests preoperatively, and at 3 months and more than 6 months after the operation.

RESULTS

In the lobectomy group, FEV1 vital capacity (VC), and maximum oxygen consumption (VO2max) decreased significantly 3 months after the operation and improved after more than 6 months, but did not reach the preoperative values. In the pneumonectomy group, FEV1 VC, and VO2max decreased 3 months after the surgery and the values did not recover thereafter. In comparison with preoperative values, the functional percentage losses after more than 6 months for lobectomies and pneumonectomies were 11.2% and 36.1% for FEV1, 11.6% and 40.1% for VC, and 13.3% and 28.1% for VO2max, respectively. Postoperatively, maximal minute ventilation (VEmax), the maximal heart rate percentage, and maximal O2 pulse during the exercise test significantly decreased in both the lobectomy and pneumonectomy groups. Nevertheless, VEmax and O2 pulse improved more than 6 months after lobectomy compared with the value at 3 months, but not after pneumonectomy. Breathing reserve did not differ before and after surgery in the lobectomy group, although it decreased significantly after surgery in the pneumonectomy group. Subjectively, postoperative exercise after lobectomy was limited by leg discomfort (64% at more than 6 months after surgery); after pneumonectomy, exercise was limited by dyspnea (60%).

CONCLUSIONS

These results suggest that there are differences between lobectomy and pneumonectomy for lung cancer in terms of recovery and limitation of exercise capacity.

Fixed maximal stroke index in patients after pneumonectomy

Patients who have undergone pneumonectomy (PNX) show limited exercise capacity, partly attributable to an impaired stroke index (SI). To determine whether this limitation is due to deconditioning, we assessed exercise performance and cardiopulmonary function in seven patients after PNX (age: 59 +/- 2 yr, mean +/- SEM) and eight normal, healthy nonsmokers (52 +/- 3 yr) before and after an ergometer exercise training program for 30 min per day, 5 d per week, for 8 wk at 65% of measured maximal O2 uptake. Lung volume, diffusing capacity of carbon dioxide (DL(CO)) and cardiac index (CI) were determined during steady-state exercise by a rebreathing method. Exercise endurance was measured at 80% of maximal power. As compared with normal subjects, patients who had had PNX showed diminished maximal oxygen uptake (VO2max), as well as diminished lung volumes, ventilatory capacities, and maximal cardiac and stroke indexes. After training, VO2max, endurance, and peripheral O2 extraction improved in both groups. However, maximal cardiac and stroke indexes increased only in normal subjects and not in patients. We conclude that an irreversibly fixed maximal SI is a major source of exercise limitation after PNX, probably because of pulmonary arterial hypertension and/or mechanical distortion of the cardiac fossa. Ventilatory impairment after PNX did not prevent a training-induced increase in VO2max. Exercise training confers significant functional benefit on postpneumonectomy patients by enhancing peripheral O2 extraction.

Cardiopulmonary function after pulmonary lobectomy in patients with lung cancer

The effects of pulmonary lobectomy on cardiopulmonary function were investigated in 9 patients with lung cancer. Hemodynamic studies at rest and during exercise were performed before and 4 to 6 months after the operation. Differences in hemodynamics between before and after operation were observed with respect to heart rate, pulmonary arterial pressure, pulmonary vascular resistance index, and stroke volume index. Heart rate, pulmonary arterial pressure, and pulmonary vascular resistance index were significantly increased after operation, whereas stroke volume index was significantly decreased. It is thought that cardiac index was preserved by the increase in heart rate despite a decrease in stroke volume index associated with the decreased pulmonary vascular bed after the operation. When driving pressure and cardiac index were studied after operation, the pressure at rest and during exercise was higher, and the pressure-flow curve increased more steeply, as compared with the preoperative values. These results suggest a significant deterioration in cardiopulmonary function after lobectomy. As the patient characteristics were heterogeneous (five lobectomies and four bilobectomies), and their findings are limited, additional studies may be necessary in the future.

What is the value of preoperative pulmonary function testing?

This article reviews the current information regarding the value of different tests of lung function in patients undergoing abdominal or thoracic surgery. Risk factors as well as the pathophysiology of postoperative pulmonary complications are also discussed. Finally, a rational approach synthesizing clinical features with pulmonary function test results to estimate risk and minimize complication is presented.

Respiratory muscle limitation in patients after pneumonectomy

Exercise capacity is significantly impaired in postpneumonectomy patients who have relatively normal remaining lungs. Our objectives are to determine (1) the nature and extent of mechanical ventilatory abnormalities and oxygen cost of breathing in such patients, and (2) the efficacy of a selective respiratory muscle training program in improving ventilatory and exercise performance. A group of eight postpneumonectomy and eight normal subjects (mean ages 59 and 50 yr, respectively) were studied during steady-state exercise and resting voluntary hyperventilation. Ventilation, work of breathing, cardiac output, and oxygen costs of breathing were determined. Four postpneumonectomy and five normal subjects were studied before and after a respiratory muscle training program. In patients after pneumonectomy compared with normal control subjects, maximal oxygen uptake (VO2) was 56% lower (p < 0.001). Work of breathing was significantly higher at a given ventilation. Mechanical efficiency of ventilation was lower by 44% (p < 0.05). Near maximal VO2, 48% of any additional increment of total-body VO2 was required to sustain the associated increment in ventilatory work, compared with 28% in normal subjects (p < 0.05), suggesting that competition between respiratory and nonrespiratory muscles for oxygen delivery is a significant factor limiting exercise after pneumonectomy. After respiratory muscle training, maximal respiratory pressures improved but maximal sustained ventilation and maximal VO2 did not improve significantly, suggesting that selective respiratory muscle training is of limited utility in postpneumonectomy patients.

Preoperative cardiopulmonary exercise testing: determining the limit to exercise and predicting outcome after thoracotomy

Over the past 15 years evaluation of the patient with exertional complaints has changed from a simple qualitative estimate of overall fitness to a detailed assessment of cardiovascular and pulmonary pathophysiology. By quantifying exercise impairment and identifying the physiological limit to exercise, CPEx can help direct and evaluate the efficacy of medical and surgical interventions. Although no clear consensus has emerged, an objective determination of the etiology of exercise intolerance may also help identify the patient at increased risk for postthoracotomy complications.

Estimation of diffusion limitation after pneumonectomy from carbon monoxide diffusing capacity

In three foxhounds, diffusing capacity for carbon monoxide (DLCO) was reduced by 25-30% after left pneumonectomy. Based on previous morphometric data in animals and physiologic data in humans, this reduction should not result in any impairment in gas exchange. However, experimental evidence indicates that diffusion limitation develops during exercise after pneumonectomy. Our objective is to determine whether this diffusion limitation to gas exchange can be predicted from physiologic measurements of DLCO. DLCO measured by the rebreathing technique was translated into diffusing capacity for O2 (DLO2) using an average conversion factor for canids obtained morphometrically (Weibel et al., Respir. Physiol. 54: 173-188, 1983). Arterial O2 saturation (SaO2) at various intensities of steady state exercise was calculated from DLO2 and measured values of O2 consumption, alveolar PO2, hemoglobin and arterial pH, and compared to observed SaO2. After pneumonectomy, SaO2 declined progressively with increasing exercise load. In all dogs, the observed pattern of arterial O2 saturation could be predicted from DLCO measured at similar work loads. The relationship between predicted (Pr) and observed (Ob) SaO2 is: SaO2(Pr) = 22.73 + 0.77SaO2(Ob), r = 0.92. The slope is significantly less than 1.0 (P less than 0.005), indicating that other factors must also contribute to arterial desaturation. We conclude that physiologic measurement of DLCO is a meaningful indicator of diffusion limitation to gas exchange. In the foxhound, a modest reduction in DLCO significantly impairs O2 transport during exercise; but other gas exchange abnormalities, e.g. ventilation perfusion inhomogeneity, must also develop.

Cardiopulmonary function after lobectomy or pneumonectomy for pulmonary neoplasm

Resection of pulmonary tissue for bronchial carcinoma causes a decrease in vital capacity of 15% after lobectomy and 35-40% following pneumonectomy. After operation the lung becomes stiffer and elastic recoil pressure and transdiaphragmatic pressure at TLC increase. Maximum effort tolerance decreases after pneumonectomy with a normal pulmonary artery pressure at rest and an increase in pulmonary artery pressure and in pulmonary vascular resistance on effort, compared to preoperative values. Cardiac output and stroke volume during effort show a decrease after operation with an increase in peripheral arterial blood pressure and in peripheral vascular resistance. Arterial oxygen saturation on effort decreases after pneumonectomy, possibly due to the absolute decrease in diffusing capacity. When comparing resting and exercise values at identical work loads, increases in systemic arterial blood pressure, pulmonary and systemic vascular resistance and arteriovenous oxygen difference were similar although generally less pronounced after lobectomy compared to pneumonectomy; cardiac output, stroke volume and oxygen consumption showed the same tendency to decrease after lobectomy and pneumonectomy.

Effect of lung resection on blood lactate threshold in lung cancer patients

We studied the effect of a decrease in vital capacity (VC) on the blood lactate threshold detected during exercise in 16 preoperative (PRE) and 10 postoperative (POST) lung cancer patients who had undergone lobectomy or pneumonectomy. The PRE patients were selected on the basis of having normal preoperative pulmonary function. The POST patients were selected on the basis of having normal preoperative pulmonary function and a postoperative VC of less than 80%. The oxygen consumption/body surface area at a 2.2 m.mol.l-1 arterial lactate concentration (VO2/BSA at La-2.2) was adopted as the blood lactate threshold. VC/BSA in the POST group significantly correlated with VO2/BSA at La-2.2 (r = 0.85, P less than 0.01), but not in the PRE group. SaO2 at La-2.2 was 95.4 +/- 1.5% in the PRE group and 95.2 +/- 1.3% in the POST group. SaO2 at La-2.2 did not correlated with VC/BSA in either group. The hemoglobin concentration (Hb) in the arterial blood correlated significantly with VC/BSA in the POST group (r = 0.65, P less than 0.05) but not in the PRE group. These results indicate that VO2/BSA at La-2.2 was restricted by VC in patients with restrictive pulmonary function disorder. Of the three elements of oxygen delivery, Hb was a limiting factor for VO2/BSA at La-2.2 but SaO2 was not. Cardiac output, which was not measured in our study, was speculated to be another limiting factor for VO2/BSA at La-2.2.

Maximal oxygen consumption in patients with lung disease

A theoretical model for oxygen transport assuming a series linkage of ventilation, diffusion, oxygen uptake by erythrocytes, cardiac output, and oxygen release was used to calculate expected values for maximal oxygen intake (VO2max) of patients with various pulmonary disorders 22 patients with either restrictive or obstructive ventilatory impairment were studied at rest and maximal exercise. When exercise measurements of maximal pulmonary blood flow (QCmax), oxygen capacity, membrane diffusing capacity for CO, pulmonary capillary blood volume, alveolar ventilation, and mixed venous oxygen saturation were employed as input values, predictions of VO2max from the model correlated closely with measured values (r = 0.978). Measured VO2max was 976+/-389 ml/min (45.3+/-13% of predicted normal), and VO2max predicted from the model was 1,111+/-427 ml/min. The discrepancy may in part reflect uneven matching of alveolar ventilation, pulmonary capillary blood flow, and membrane diffusing capacity for CO within the lung; uniform matching is assumed in the model so that mismatching will impair gas exchange beyond our predictions. Although QCmax was less than predicted in most patients (63.6+/-19.6% of predicted) the model suggests that raising QCmax to normal could have raised VO2max only 11.6+/-8.8% in the face of existent impairment of intrapulmonary gas exchange. Since pulmonary functions measured at rest correlated well with exercise parameters needed in the model to predict VO2max we developed a nomogram for predicting VO2max from resting CO diffusing capacity, the forced one second expired volume, and the resting ratio of dead space to tidal volume. The correlation coefficient between measured and predicted VO2max, by using this nomogram, was 0.942.

Working capacity and cardiopulmonary function after extensive lung resections

Twelve patients were investigated 7-168 months after pneumonectomy. Two of them had also undergone resection of a segment of the remaining lung. The follow-up included studies of working capacity, static and dynamic lung volumes, alveolar gas exchange, diffusing capacity, blood gases and central haemodynamics with right heart catheterization. The working capacity was markedly reduced, limited by dyspnoea in 10/12 patients. The dyspnoea was related to reduced static and dynamic lung volumes (50% of normal). The diffusing capacity of the remaining lung was half of that predicted for two lungs from total haemoglobin and age and the transfer capacity of the lungs for oxygen was loaded to its maximum even at submaximal loads, resulting in a decrease in arterial oxygen tension and saturation and an increase in the alveolo-arterial oxygen tension difference. The central circulation was hypokinetic at submaximal loads and the stroke volume was small. The reduction in working capacity was caused by a number of coacting factors, inactivity, reduced lung function and small stroke volume. It was not possible from the present investigation to single out any of these factors as the main cause of dyspnoea during exercise and thereby the reduced working capacity.

Cardiopulmonary performance at rest and during exercise in seven patients with increased transradiancy of one lung ("Macleod's syndrome")

A group of seven patients with increased transradiancy of one lung included four with chronic bronchitis. The function of the two lungs combined was assessed by measurement of the lung volumes, airway resistance, and carbon monoxide uptake at rest, and by measurement of pulmonary ventilation, gas exchange, blood gases, and cardiac output at rest and during steady state exercise. The contribution of the hypertransradiant lung to the overall functional abnormalities at rest was estimated using a radioactive gas technique.

All the patients had airway obstruction. Pulmonary gas exchange was only mildly affected at rest because of equal reduction of ventilation and perfusion in the abnormal lung, but during exercise ventilation-perfusion inequality increased in some of the patients. Cardiac output was low in five patients during exercise and in four there was excessive lactate production. The greatest physiological abnormalities were seen in two of the chronic bronchitics who had abnormalities of ventilation and perfusion in both lungs.

We suggest that a pulmonary vascular abnormality resulting in reduced cardiac output, as well as ventilatory impairment due to airway obstruction, may contribute to the limited exercise capacity of these patients.