Breathing Reserve Research Articles

Prolonged Oxygen Kinetics During Constant Workload Submaximal Exercise Is Associated With Disease Severity in Adult Subjects With Cystic Fibrosis.

The goal of this study was to explore the relation between oxygen kinetics during constant work load submaximal cardiopulmonary exercise test (CPET) and disease severity in adult subjects with cystic fibrosis. Fourteen adult subjects with cystic fibrosis (CF; 8 males, 22 ± 4 y old) and a mean Schwachman score of 73 ± 11 and 10 healthy individuals (5 males, 29 ± 4 y old) underwent pulmonary function tests at rest, maximal and constant work load submaximal CPET on a cycloergometer. Breath-by-breath analysis was used for measuring oxygen kinetic parameters and the time constant (tau), expressing phase 2 of submaximal CPET. Subjects with CF had a significantly prolonged tau compared with healthy subjects (42.3 ± 21.5 vs. 29.3 ± 6.4, s, P < .05). The tau during phase 2 was inversely correlated with FEV1(% pred) (r = -0.77, P = .001), breathing reserve (r = -0.74, P = .003), V̇O2peak (r = -0.53, P = .049), V̇O2/t slope (r = -0.58, P = .03), and Schwachman score (r = -0.80, P = .001). In a multivariate regression model including all the above variables, the Schwachman score (β = -0.697, P = .002) emerged as independent predictor of tau (R2 = 0.719, P = .001). We conclude that adult subjects with CF present significant prolonged oxygen kinetics during constant work load submaximal exercise in relation to disease severity. Thus, submaximal exercise should be considered the preferable CPET choice in adult patients with severe CF.

The effect of pulmonary hypertension on aerobic exercise capacity in lung transplant candidates with advanced emphysema.

Mild pulmonary hypertension (PH) in patients with advanced COPD is common, but its effects on exercise capacity are controversial. The objective of our study was to investigate the effects of mild PH (35 > mPAP ≥ 25 mmHg) on exercise capacity in patients with advanced emphysema, candidates for lung transplantation. We retrospectively reviewed and compare the data from right heart catheterization and cardiopulmonary exercise test, performed in patients with advanced emphysema, candidate for lung transplantation. Twenty patients with emphysema and no PH and 24 patients with emphysema associated with mild PH included in the study. Both patient groups had severe airways obstruction with markedly reduced FEV1 (24.9% P ± 8.9 and 25.9% P ± 11.7, respectively), and severely reduced DLCO (35.2% P ± 17.3 and 39.2% P ± 15.9). Both patients group demonstrated mark reduction in maximum workload and peak VO2 together with increased ventilatory equivalent for CO2 and extremely low breathing reserve. There was no correlation between mPAP and any of the exercise measurement. Our study suggests that exercise capacity in patients with advanced emphysema is limited by the ventilatory impairment and the presence of mild PH has no farther impact on exercise capability.

Limitations in exercise and functional capacity in long-term postpneumonectomy patients.

Pneumonectomy results in impairments of pulmonary function and exercise intolerance associated with respiratory limitations. However, exercise capacity and functional capacity are less known at long-term followup. The aims of this study were to assess exercise tolerance and functional capacity among long-term postpneumonectomy patients and to identify the limiting factors in exercise related to comorbidities and which lung was involved. Seventeen postpneumonectomy patients aged 59 ± 13 years and 5.5 ± 4.2 years postoperation were prospectively studied. Pulmonary function tests (PFTs), cardiopulmonary exercise test (CPET), Doppler-echocardiography, 6-minute walk test (6MWT) distance, and "senior fitness tests" (SFTs) were conducted with all patients. Exercise capacity and PFT were diminished ((Equation is included in full-text article.)O2 peak; 11.5 ± 3.3 mL·kg·min, 48 ± 17% predicted, forced vital capacity % predicted; 55 ± 13, FEV1% predicted; 46 ± 14, respectively). Most patients presented with low exercise cardiovascular parameters and normal breathing reserve (17 ± 12 L) during CPET. No significant differences were shown between right and left pneumonectomy and comorbidities related to exercise limitations (χ= 1.96, P = .376). Functional capacity in walking and SFTs were near normal (6MWT distance; 490 ± 15 m, 89 ± 25% predicted). Echocardiography showed normal left ventricle systolic function (ejection fraction, 60 ± 4%) with mildly elevated systolic pulmonary arterial pressure (38 ± 12 mm Hg). Long-term postpneumonectomy patients demonstrated decreased exercise capacity, limited primarily by the cardiovascular system regardless of lung resection side or comorbidities, although tests of functional capacity were near normal. Most patients can maintain near normal life in activities of daily living, but the long-term cardiopulmonary exercise function should be considered for meticulous evaluation and clinical care to preserve physiological reserves.

Prediction of mortality in adolescents with cystic fibrosis.

Lung function, nutritional status, and parameters of exercise capacity are known predictors of mortality in patients with cystic fibrosis (CF). The aim of the current study was to use these important parameters to develop a multivariate model to predict mortality in adolescent patients with CF. A total of 127 adolescents with CF (57 girls) with a mean age of 12.7 ± 0.9 yr and a mean percentage of predicted forced expired volume in 1 s (FEV1% predicted) of 77.7% ± 15.6% were included. Cardiopulmonary exercise testing-derived parameters, nutritional status, and resting lung functions were dichotomized according to the criterion value determined using receiver operating characteristic curves. Body mass index (BMI), FEV1%predicted, predicted peak oxygen uptake corrected for body weight (VO2 peak/kg%predicted), peak minute ventilation (VE peak), peak VE/VO2, peak VE/VCO2, and breathing reserve were included in a multivariate model. The Cox proportional hazards model was used to determine the combination of parameters that best predicted mortality and/or lung transplantation. The mean duration of follow-up was 7.5 ± 2.7 yr, during which, nine of the 127 patients (7.1%) died and six (4.7%) underwent lung transplantation. Mortality in this population was best predicted by the model that included FEV1%predicted (hazard ratio, 17.13; 95% confidence interval (CI), 3.76-78.06), peak VE/VO2 (hazard ratio, 5.92; 95% CI, 1.27-27.63), and BMI (hazard ratio, 5.54; 95% CI, 1.82-16.83). The currently developed model consisting of BMI, FEV1%predicted, and VE/VO2 is a strong predictor of mortality rate in adolescents with CF. This prediction equation may be useful in clinical practice to detect patients with a high risk of mortality and to provide them with additional therapy earlier.

Exercise intolerance in obese children and adolescents

Abstract Background: Abnormal lung function has been reported in the obese population and is associated with the severity of obesity. Objectives: To identify abnormal lung function in obese children and adolescents, and examine the cardiopulmonary response of those who have abnormal lung functions during exercise, and to reveal predictors of exercise intolerance in this population. Methods: Fifty obese participants aged 8–18 years (56% male; mean age 13.2 ± 2.0 years; mean BMI 33.0 ± 3.6 kg/m2, mean BMI z score 3.1 ± 0.3) underwent spirometry, lung volume evaluation, and a cardiopulmonary exercise test. Results: Lung function abnormalities and exercise intolerance because of pulmonary limitations were found in 36% and 74% of the participants, respectively. A comparison of participants with normal and abnormal lung functions revealed a lower breathing reserve and a higher ventilatory equivalent for CO2 production (VE/VCO2) during exercise in those who had lung function abnormalities (18 ± 15 vs 30±10%, P &lt;0.001 and 30.3 ± 3.3 vs 29.6 ± 3.1; P = 0.02, respectively). Exercise intolerant participants had a higher BMI z score compared with those who were not (3.1 ± 0.3 vs 2.9 ± 0.3; P = 0.03). BMI z score ≥ 2.84 had an 80% sensitivity and 67% specificity for predicting exercise intolerance in this population. Conclusions: Evaluations of lung function and exercise capacity should be included in the follow-up planning for obese children and adolescents. A BMI z score ≥ 2.84 was most sensitive for predicting exercise intolerance in this population.

Modified Chrispin-Norman Score: Correlation With Peak Exercise Capacity and Efficiency of Ventilation in Children With Cystic Fibrosis

The modified Chrispin-Norman radiography score (CNS) is used in evaluation of radiographic changes in children with cystic fibrosis (CF). We evaluated the correlation of modified CNS with peak exercise capacity (Wpeak) and ventilatory efficiency (reflected by breathing reserve index-BRI) during progressive cardiopulmonary exercise testing (CPET). Thirty-six children aged 8-17 years were stratified according to their CNS into 3 groups: mild (<10), moderate (10-15), and severe (>15). CPET was performed on a cycle ergometer. Lung function tests included spirometry and whole-body plethysmography. Patients with higher CNS had lower FEV1 (p < .001), Wpeak predicted (%; p = .01) and lower mean peak oxygen consumption (VO2peak/kg; p = .014). The BRI at the anaerobic threshold and at Wpeak was elevated in patients with the highest CNS values (p < .001). The modified CNS correlates moderately with Wpeak (R = -0.443; p = .007) and BRI (R = -0.419; p = .011). Stepwise multiple linear regression showed that RV/TLC was the best predictor of Wpeak/pred (%; B = -0.165;  = -0.494; R2 = .244; p = .002). Children with CF who have high modified CNS exhibit decreased exercise tolerance and ventilatory inefficacy during progressive effort.

Abnormal spirometry after the Fontan procedure is common and associated with impaired aerobic capacity.

Impaired exercise capacity is common after the Fontan procedure and is attributed to cardiovascular limits. The Fontan circulation, however, is also distinctively vulnerable to unfavorable lung mechanics. This study aimed to define the prevalence and physiological relevance of pulmonary dysfunction in patients with Fontan physiology. We analyzed data from the Pediatric Heart Network Fontan Cross-Sectional Study to assess the prevalence and pattern of abnormal spirometry in Fontan patients (6-18 yr old) and investigated the relationship between low forced vital capacity (FVC) and maximum exercise variables, including peak O2 consumption (Vo2peak), among those who demonstrated adequate effort (n = 260). Average ages at the time of exercise testing and Fontan completion were 13.2 ± 3.0 and 3.5 ± 2.2 yr old, respectively. Aerobic capacity was reduced (Vo2peak: 67.3 ± 15.6% predicted). FVC averaged 79.0 ± 14.8% predicted, with 45.8% having a FVC less then the lower limit of normal. Only 7.8% demonstrated obstructive spirometry. Patients with low FVC had lower Vo2peak (64.4 ± 15.9% vs. 69.7 ± 14.9% predicted, P < 0.01); low FVC independently predicted lower Vo2peak after adjusting for relevant covariates. Among those with Vo2peak < 80% predicted (n = 204/260), 22.5% demonstrated a pulmonary mechanical contribution to exercise limitation (breathing reserve < 20%). Those with both low FVC and ventilatory inefficiency (minute ventilation/CO2 production > 40) had markedly reduced Vo2peak (61.5 ± 15.3% vs. 72.0 ± 14.9% predicted, P < 0.01) and a higher prevalence of pulmonary mechanical limit compared with patients with normal FVC and efficient ventilation (36.1% vs. 4.8%). In conclusion, abnormal FVC is common in young patients after the Fontan procedure and is independently associated with reduced exercise capacity. A large subset has a pathologically low breathing reserve, consistent with a pulmonary mechanical contribution to exercise limitation.

Lung, not only heart

Lung, not only heart

Physical Activity Impairment in Depressed COPD Subjects

Limited exercise tolerance is a cardinal clinical feature in COPD. Depression and COPD share some clinical features, such as reduced physical activity and impaired nutritional status. The aim of the present study was to evaluate maximum and daily physical activities and the nutritional status of COPD patients affected or not by depression. In 70 COPD out-patients, daily and maximum physical activities were assessed by multisensor accelerometer armband, 6-min walk test, and cardiopulmonary exercise test. Mental status, metabolic/muscular status, and systemic inflammation were evaluated using the Hospital Anxiety and Depression Scale, by bioelectrical impedance analysis, and with regard to fibrinogen/C-reactive protein, respectively. Depressed subjects (27% of the sample) showed a similar level of respiratory functional impairment but a higher level of shortness of breath and a worse quality of life compared to non-depressed subjects (P < .05). Specifically, they displayed a physical activity impairment consisting of a reduced number of steps per day, a lower peak of oxygen consumption, an early anaerobic threshold, and a reduced distance in the 6-min walk test (P < .05) but the same nutritional status compared to non-depressed subjects. In the multivariate analysis, a reduced breathing reserve, obesity, and a higher level of shortness of breath, but not depression, were found to be independent factors associated with a reduced daily number of steps. Our study found that depressed COPD patients have a reduced daily and maximum exercise capacity compared to non-depressed patients. This further suggests the potential utility of screening for depression in COPD.

Does the Calculated Breathing Reserve Correlate With the Directly Measured Breathing Reserve During Cardiopulmonary Exercise Testing?

SESSION TITLE: Physiology/PFTs/Rehabilitation Posters

Reference Values for Cardiorespiratory Response and Fitness on the Treadmill in a 20- to 85-Year-Old Population

Existing reference values for clinical exercise testing have been derived from small nonrandom samples, lacking women and older individuals and some with poor or no maximal end criteria. The objective was to study the cardiorespiratory response during maximal exercise in a representative predominantly Caucasian sample of men and women. Nine hundred four randomly sampled men and women, 20 to 85 years old, exercised on a treadmill to exhaustion. Oxygen uptake (V.O2), heart rate (HR), BP, blood lactate concentration, and ventilatory variables were measured. Seven hundred fifty-nine participants met the criteria for an acceptable maximal V.O2 (V.O2max) based on a respiratory exchange ratio≥1.10 or a Borg score≥17. In the 20- to 29-year-old age group, V.O2max (mL/kg/min) was 40.3 (±7.1) in women and 48.6 (±9.6) in men. A linear decline (8% per decade) was observed after age 30 years in both sexes. Maximal HR decreased with age by ±6.3 beats/min per decade. The maximal oxygen pulse was 33% lower in women and decreased significantly with age in both sexes by 5% and 3% per decade for women and men, respectively. Women's maximal ventilation was 66% that of men and decreased with age after 40 to 49 years in both sexes. Breathing reserve was higher and blood lactate was lower in women than in men. This study establishes reference values for V.O2max (absolute, relative to body weight and fat-free weight), maximal HR, oxygen pulse, BP, ventilation, breathing reserve, respiratory exchange ratio, and blood lactate concentration during maximal exercise on treadmill in a large population.

Assessing Maximal Exercise Capacity: Peak Work or Peak Oxygen Consumption?

Exercise capacity assessed by cardiopulmonary exercise testing is usually measured by peak oxygen consumption (VO2). However, not uncommonly, patients achieve a relatively higher work load (peak work) compared to their peak VO2. In these situations it is difficult to know which parameter to use in assessing exercise capacity. The purpose of this study was to determine whether there are distinguishing physiological characteristics of patients with discordance between percent-of-predicted peak work versus peak VO2, in order to understand how to use these measurements in interpreting exercise capacity. We conducted a retrospective study of 172 cardiopulmonary exercise tests performed at our institution between 2003 and 2010. The subjects in the higher peak work group demonstrated higher ventilatory efficiency (lower slope of minute ventilation to carbon dioxide production) and lung function (FEV1 and FVC), a greater breathing reserve (higher breathing reserve, lower VE/maximal voluntary ventilation), and achieved a higher maximal heart rate. Subjects in the higher maximum VO2 group were heavier, had lower ventilatory efficiency, and had a reduced breathing reserve. Multivariate logistic regression analysis showed that the predominant independent factors associated with group assignment were body mass index, breathing reserve, and peak heart rate. The subjects with higher percent-of-predicted peak work than peak VO2 had a lower body mass index, a greater breathing reserve, and a higher peak heart rate. The observation that there are distinguishing physiological features between those who have a higher peak work and those who have higher peak VO2 provides insight into the underlying processes determining maximal exercise capacity.

Static Hyperinflation Is Associated With Decreased Peak Exercise Performance in Children With Cystic Fibrosis

We evaluated the exercise capacity of children with cystic fibrosis to determine whether ventilatory limitation associated with static hyperinflation is related with decreased exercise capacity, thus predisposing these children to arterial hypoxemia during progressive exercise. Thirty-seven children, ages 8-17 years, underwent spirometry, body plethysmography, and cardiopulmonary exercise testing after arterial catheter placement. According to the ratio of residual volume to total lung capacity (RV/TLC), the subjects were categorized as either with (RV/TLC > 30%) or without static hyperinflation (RV/TLC < 30%). Children with static hyperinflation showed lower values of maximum load per kilogram (% predicted) (P = .01), which was aggravated by ventilatory limitation (FEV(1) < 80% of predicted, peak oxygen consumption [% predicted] < 85%, and breathing reserve index > 0.7). Subjects with ventilatory limitation had significantly lower oxygen saturation (P = .04) and hypoxemia (P = .03) than did subjects without ventilatory limitation. In children with cystic fibrosis, static hyperinflation and ventilatory limitation are associated with decrease in exercise performance, oxygen saturation, and P(aO(2)) during maximum cardiopulmonary exercise testing. All children with cystic fibrosis who exhibit static hyperinflation and ventilatory limitation may require S(aO(2)) monitoring during progressive exercise.

Differences in gas exchange between severities of chronic obstructive pulmonary disease

Impaired ventilation on cardiopulmonary exercise test (CPET) is seen in patients with chronic obstructive pulmonary disease (COPD). However, evaluation of the differences of abnormal gas exchange in COPD according to GOLD severity criteria is limited. A retrospective review was performed on all COPD patients referred for CPET at our center between 1998 and 2010. There were 548 patients compared according to GOLD severity. GOLD groups were significantly different from each other in regards to pressure of end-tidal carbon dioxide (PETCO2) with progressively higher PETCO2 with increasing GOLD severity. Ratio of minute ventilation to carbon dioxide production (V˙E/V˙CO2) and exercise capacity as measured by and V˙O2 % and work rate in watts% was inversely proportional to GOLD severity. Breathing reserve, minute ventilation, and tidal volume at peak exercise were significantly decreased with increasing disease severity between GOLD groups. We concluded that gas exchange is distinctive among different GOLD severity groups; specifically, GOLD 3 and 4 have a significantly higher PETCO2 and a significantly lower V˙E/V˙CO2 than GOLD 2.

Ventilatory and Cardiocirculatory Exercise Profiles in COPD: The Role of Pulmonary Hypertension

Background Pulmonary hypertension (PH) is a well-recognized complication of COPD. The impact of PH on exercise tolerance is largely unknown. We evaluated and compared the circulatory and ventilatory profiles during exercise in patients with COPD without PH, with moderate PH, and with severe PH. Methods Forty-seven patients, GOLD (Global Initiative for Chronic Obstructive Lung Disease) stages II to IV, underwent cardiopulmonary exercise testing and right-sided heart catheterization at rest and during exercise. Patients were divided into three groups based on mean pulmonary artery pressure (mPAP) at rest: no PH (mPAP, < 25 mm Hg), moderate PH (mPAP, 25-39 mm Hg), and severe PH (mPAP, ≥ 40 mm Hg). Mixed venous oxygen saturation (Svo2) was used for evaluating the circulatory reserve. Paco2 and the calculated breathing reserve were used for evaluation of the ventilatory reserve. Results Patients without PH (n = 24) had an end-exercise Svo2 of 48% ± 9%, an increasing Paco2 with exercise, and a breathing reserve of 22% ± 20%. Patients with moderate PH (n = 14) had an exercise Svo2 of 40% ± 8%, an increasing Paco2, and a breathing reserve of 26% ± 15%. Patients with severe PH (n = 9) had a significantly lower end-exercise Svo2 (30% ± 6%), a breathing reserve of 37% ± 11%, and an absence of Paco2 accumulation. Conclusion Patients with severe PH showed an exhausted circulatory reserve at the end of exercise. A profile of circulatory reserve in combination with ventilatory impairments was found in patients with COPD and moderate or no PH. The results suggest that pulmonary vasodilation might only improve exercise tolerance in patients with COPD and severe PH. Pulmonary hypertension (PH) is a well-recognized complication of COPD. The impact of PH on exercise tolerance is largely unknown. We evaluated and compared the circulatory and ventilatory profiles during exercise in patients with COPD without PH, with moderate PH, and with severe PH. Forty-seven patients, GOLD (Global Initiative for Chronic Obstructive Lung Disease) stages II to IV, underwent cardiopulmonary exercise testing and right-sided heart catheterization at rest and during exercise. Patients were divided into three groups based on mean pulmonary artery pressure (mPAP) at rest: no PH (mPAP, < 25 mm Hg), moderate PH (mPAP, 25-39 mm Hg), and severe PH (mPAP, ≥ 40 mm Hg). Mixed venous oxygen saturation (Svo2) was used for evaluating the circulatory reserve. Paco2 and the calculated breathing reserve were used for evaluation of the ventilatory reserve. Patients without PH (n = 24) had an end-exercise Svo2 of 48% ± 9%, an increasing Paco2 with exercise, and a breathing reserve of 22% ± 20%. Patients with moderate PH (n = 14) had an exercise Svo2 of 40% ± 8%, an increasing Paco2, and a breathing reserve of 26% ± 15%. Patients with severe PH (n = 9) had a significantly lower end-exercise Svo2 (30% ± 6%), a breathing reserve of 37% ± 11%, and an absence of Paco2 accumulation. Patients with severe PH showed an exhausted circulatory reserve at the end of exercise. A profile of circulatory reserve in combination with ventilatory impairments was found in patients with COPD and moderate or no PH. The results suggest that pulmonary vasodilation might only improve exercise tolerance in patients with COPD and severe PH.

Silicosis in sandblasters of shipyard versus silicosis in stone carvers in Brazil: A comparison of imaging findings, lung function variables and cardiopulmonary exercise testing parameters

ObjectivesTo compare imaging findings, lung function variables and cardiopulmonary exercise testing (CPET) results between Brazilian sandblasters of shipyard and stone carvers with silicosis. MethodsOf the 41 patients, 25 subjects were sandblasters and 16 were stone carvers, with median ages of 52 and 46.4 years, respectively. All of the patients underwent pulmonary function tests (PFTs) and CPET. Chest radiographs were classified according to the International Labour Organization recommendations. The following parameters were examined through the use of high-resolution computerized tomography (HRCT): nodules, progressive massive fibrosis (PMF), emphysema, and intrathoracic lymph node enlargement. ResultsLarge opacities on chest radiography were observed in 76% of sandblasters and only 18.7% of stone carvers. Using HRCT, PMF was identified in 92% of sandblasters and only 43.7% of stone carvers. Although carbon monoxide diffusing capacity results were significantly different between the sandblasters and stone carvers, these differences were more pronounced in the CPET results. While 92% of sandblasters failed to reach at least 80% of their predicted peak oxygen uptake (VO2), this was observed for only 43.7% of stone carvers. A breathing reserve of less than 25% was observed in 40.5% of sandblasters but not in any of the stone carvers. ConclusionIn silicosis, imaging findings, lung function and CPET results are strongly influenced by the type of exposure to silica dust. Additionally, CPET abnormalities are more pronounced compared to measurements taken at rest.

Exercise Testing in Survivors of Intensive Care—Is There a Role for Cardiopulmonary Exercise Testing?

Abstract Purpose The aims of this study were to assess the feasibility of cardiopulmonary exercise testing (CPET) for the early assessment of cardiorespiratory fitness in general adult intensive care unit (ICU) survivors and to characterize the pathophysiology of exercise limitation in this population. Methods Fifty general ICU survivors (ventilated for ≥5 days) performed a maximal cycle ergometer CPET within 6 weeks of hospital discharge. Health-related quality of life was measured by the Medical Outcome Study Short Form 36 version 2.0 questionnaire. Results Fifty patients (median age, 57 years; median Acute Physiology And Chronic Health Evaluation II score, 16) completed a CPET 24 ± 14 days after hospital discharge with no adverse events. Significant exercise limitation was present with peak V o 2 56% ± 16% predicted and anaerobic threshold (AT) 41% ± 13% of peak predicted V o 2. Prospectively stratified subgroup comparison showed that patients ventilated for 14 days or more had a significantly lower AT and peak V o 2 than those ventilated for 5 to 14 days (AT: 9.6 vs 11.7 mL/kg per minute O2, P = .009; peak V o 2: 12.9 vs 15.3 mL/kg per minute O2, P = .022). At peak exercise, heart rate reserve was 25% ± 14%, breathing reserve was 47% ± 19%, and the respiratory exchange ratio was 0.96 ± 0.11. Ventilatory equivalents for CO2 (Eq co 2) were 39 ± 9. Conclusions Significant exercise limitation is evident in patients who have had critical illness. Etiology of exercise limitation appears multifactorial, with general deconditioning and muscle weakness as major contributory factors. Early CPET appears a practical method of assessing exercise capacity in ICU survivors. Cardiopulmonary exercise testing could be used to select patients who may benefit most from a targeted physical rehabilitation program, aid in exercise prescription, and help assess the response to intervention.

Encouraging Pulmonary Outcome for Surviving, Neurologically Intact, Extremely Premature Infants in the Postsurfactant Era

The aim of this study was to determine the long-term pulmonary outcome of extreme prematurity at a single tertiary-care center from 1997 to 2001 in the postsurfactant era. We assessed symptoms, exhaled nitric oxide, spirometry, methacholine challenge (provocative concentration of methacholine required to decrease FEV₁ by 20% [PC(20)]), lung volumes, diffusion, and cardiopulmonary exercise tolerance. Of 279 infants born, 192 survived to discharge, and 79 of these developed bronchopulmonary dysplasia (BPD) (65 mild, 12 moderate, two severe). We studied a subgroup of 53 neurologically intact preterm subjects aged 10 ± 1.5 years (28 with BPD [born, 26.2 ± 1.4 weeks; birth weight, 821 ± 164 g] and 25 without BPD [born, 27.2 ± 1 weeks; birth weight, 1,050 ± 181 g]) and compared them with 23 term control subjects. Of the BPD cases, 21 were mild, seven were moderate, and none was severe; 77.4% of subjects received antenatal steroids, and 83% received postnatal surfactant. Sixty percent of the preterm subjects wheezed at age < 2 years compared with 13% of the control subjects (P < .001), but only 13% wheezed in the past year compared with 0% of control subjects (not significant). For preterm and control subjects, respectively (mean ± SD), FEV₁ % predicted was 85% ± 10% and 94% ± 10% (P < .001), with limited reversibility; residual volume/total lung capacity was 29.3% ± 5.5% and 25% ± 8% (P < .05); diffusing capacity/alveolar volume was 89.6% ± 9.2% and 97% ± 10% (P < .005); and PC(20) was 6.5 ± 5.8 mg/mL and 11.7 ± 5.5 mg/mL (P < .001). PC(20) was < 4 mg/mL in 49% of preterm subjects despite normal exhaled nitric oxide. Most measurements were similar in premature subjects with and without BPD. Peak oxygen consumption and breathing reserve were normal, but % predicted maximal load (measured in Watts) was 69% ± 15% for subjects with BPD compared with 88% ± 23% for subjects without and 86% ± 20% for control subjects (P < .01). Pulmonary outcome was encouraging at mid-childhood for neurologically intact survivors in the postsurfactant era. Despite mechanical ventilation and oxygen therapy, most had no or mild BPD. Changes found probably reflect the hypoplastic lungs of prematurity.

Silicose em jateadores de areia de estaleiro versus silicose em escultores de pedra no Brasil: uma comparação dos achados de imagem, função pulmonar e teste de exercício cardiopulmonar

ObjectivesTo compare imaging findings, lung function variables and cardiopulmonary exercise testing (CPET) results between Brazilian sandblasters of shipyard and stone carvers with silicosis. MethodsOf the 41 patients, 25 subjects were sandblasters and 16 were stone carvers, with median ages of 52 and 46.4 years, respectively. All of the patients underwent pulmonary function tests and CPET. Chest radiographs were classified according to the International Labour Organization recommendations. The following parameters were examined through the use of high-resolution computerized tomography (HRCT): nodules, progressive massive fibrosis (PMF), emphysema, and intrathoracic lymph node enlargement. ResultsLarge opacities on chest radiography were observed in 76% of sandblasters and only 18.7% of stone carvers. Using HRCT, PMF was identified in 92% of sandblasters and only 43.7% of stone carvers. Although carbon monoxide diffusing capacity results were significantly different between the sandblasters and stone carvers, these differences were more pronounced in the CPET results. While 92% of sandblasters failed to reach at least 80% of their predicted peak oxygen uptake (VO2), this was observed for only 43.7% of stone carvers. A breathing reserve of less than 25% was observed in 40.5% of sandblasters but not in any of the stone carvers. ConclusionIn silicosis, imaging findings, lung function and CPET results are strongly influenced by the type of exposure to silica dust. Additionally, CPET abnormalities are more pronounced compared to measurements taken at rest.

Ventilatory Inefficiency as a Limiting Factor for Exercise in Patients With COPD

Ventilatory inefficiency increases ventilatory demand; corresponds to an abnormal increase in the ratio of minute ventilation (V_dot(E)) to CO(2) production (V_dot(CO(2))); represents increased dead space, deregulation of respiratory control, and early lactic threshold; and is associated with expiratory flow limitation that enhances dynamic hyperinflation and may limit exercise capacity. To evaluate the influence of ventilatory inefficiency over exercise capacity in COPD patients. Prospective study of 35 COPD subjects with different levels of severity, in whom cardiopulmonary stress test was performed. Ventilatory inefficiency was represented by the V_dot(E) /V_dot(CO(2)) relation. Its influence over maximal oxygen consumption (V_dot(O(2))max), power (W), and ventilatory threshold was evaluated. Surrogate parameters of cardiac function, like oxygen pulse (V_dot(O(2))/heart rate) and circulatory power (%V_dot(O(2))max × peak systolic pressure), were also evaluated. Cardiopulmonary stress test was stopped due to dyspnea with elevated V_dot(E) and marked reduction of breathing reserve. A severe increase in V_dot(CO(2)) (mean ± SD 35.9 ± 5.6), a decrease of V_dot(O(2)) (mean ± SD 75.2 ± 20%), and a decrease of W (mean ± SD 68.6 ± 23.3%) were demonstrated. Twenty-eight patients presented dynamic hyperinflation. Linear regression showed a reduction of 2.04% on V_dot(O(2>))max (P < .001), 2.6% on W (P < .001), 1% on V_dot(O(2))/heart rate (P = .049), and 322.7 units on circulatory power (P = .02) per each unit of increment in V_dot(E)/V_dot(CO(2)), respectively. Ventilatory inefficiency correlates with a reduction in exercise capacity in COPD patients. Including this parameter in the evaluation of exercise limitation in this patient population may mean a contribution toward the understanding of its pathophysiology.