Breathing Reserve at the Lactate Threshold to Differentiate a Pulmonary Mechanical From Cardiovascular Limit to Exercise

doi:10.1378/chest.113.4.913

Chest

Volume 113, Issue 4, April 1998, Pages 913-918

https://doi.org/10.1378/chest.113.4.913 Get rights and content

Study objectives

Criteria used to define the respective roles of pulmonary mechanics and cardiovascular disease in limiting exercise performance are usually obtained at peak exercise, but are dependent on maximal patient effort. To differentiate heart from lung disease during a less effort-dependent domain of exercise, the predictive value of the breathing reserve index (BRI=minute ventilation [ ${\dot{V}}_{E}$ ]/maximal voluntary ventilation [MVV]) at the lactate threshold (LT) was evaluated.

Design

Thirty-two patients with COPD and a pulmonary mechanical limit (PML) to exercise defined by classic criteria at maximum oxygen uptake ( ${\dot{V} o}_{2} \max$ ) were compared with 29 patients with a cardiovascular limit (CVL) and 12 normal control subjects. Expired gases and VE were measured breath by breath using a commercially available metabolic cart (Model 2001; MedGraphics Corp; St. Paul, Minn). Arterial blood gases, pH, and lactate were sampled each minute during exercise, and cardiac output (Q) was measured by first-pass radionuclide ventriculography (System 77; Baird Corp; Bedford, Mass) at rest and peak exercise.

Results

For all patients, the BRI at lactate threshold (BRILT) correlated with the BRI at ${\dot{V} o}_{2} \max$ (BRIMAX) (r=0.85, p<0.0001). The BRILT was higher for PML (0.73±0.03, mean±SEM) vs CVL (0.27±0.02, p<0.0001), and vs control subjects (0.24±0.03, p<0.0001). A BRILT ≥0.42 predicted a PML at maximum exercise, with a sensitivity of 96.9%, a specificity of 95.1%, a positive predictive value of 93.9%, and a negative predictive value of 97.5%.

Conclusions

The BRILT, a variable measured during the submaximal realm of exercise, can distinguish a PML from CVL.

Section snippets

Study Population

Consecutive maximum incremental cardiopulmonary exercise tests performed at the Massachusetts General Hospital (MGH) from 1991 to 1995, in which arterial blood was sampled during exercise, were evaluated. From this population, three groups were identified based on the type of exercise limit reached: normal (NL), PML, and cardiovascular limit (CVL). NL subjects consisted of individuals with suspected cardiopulmonary disease, but with a ${\dot{V} o}_{2} \max$ >80% predicted, maximum $\dot{Q} (\dot{Q} \max)$ >80%

RESULTS

The demographic characteristics of the three groups are shown in Table 1. There was no significant difference in age or Hb among groups. Weight was reduced in the PML group. There was an equal sex distribution in PML and CVL groups, but there was a male predominance in the NL group, β-Adrenergic blockers were being taken by nine (31%) CVL patients, one (12%) NL subject, and none in the PML group.

The PML group demonstrated a marked reduction in FEV₁, with hyperinflation and severely depressed

DISCUSSION

Exertional intolerance is a common but exceedingly nonspecific feature of pulmonary and cardiovascular disease. This has provided incentive for the development of cardiopulmonary exercise testing diagnostic algorithms that can be used to identify the limiting organ system in patients with concurrent disease of the lungs and heart¹^,²^,²⁰ and to direct therapy. Most variables thought to be useful in assessing an organ's functional reserve are measured at peak exercise with the implicit assumption

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Cardiopulmonary Exercise Testing in Pulmonary Vascular Disease
2021, Encyclopedia of Respiratory Medicine, Second Edition
The diagnosis of pulmonary vascular disease is often delayed because of nonspecific symptoms and an initial normal diagnostic workup performed with the patient at rest. Early diagnosis of pulmonary arterial hypertension is important as modern medical therapy has greatly improved mortality. Placing the pulmonary circulation under the stress of increased cardiac output during exercise may elicit abnormalities not found at rest and facilitate the early detection of disease.
Noninvasive cardiopulmonary exercise testing (CPET) is a useful screening test for pulmonary hypertension that can quantify the degree of exercise impairment and rule out a limit due to pulmonary parenchymal disease. Invasive CPET, with the addition of both a radial artery catheter and a pulmonary artery catheter, allows for the direct calculation of the Fick cardiac output, sampling of venous and arterial blood gases, and measurements of right and left sided pressures during exercise. Invasive CPET can add specificity to the noninvasive test and distinguish between pulmonary arterial and venous hypertension not apparent during the resting right heart catheterization. In this article, we provide an overview of both noninvasive and invasive CPET, a description of various exercise variables obtained during CPET, and analysis of their use in diagnosing disorders of pulmonary circulation.
Pulmonary Vascular and Right Ventricular Burden During Exercise in Interstitial Lung Disease
2020, Chest
Citation Excerpt :
Ventilatory reserve was reduced in ILD + rPH at the AT but similar between ILD + ePH and ILD non-PH both at peak exercise and at the AT. A primary pulmonary mechanical limit to exercise, as identified by the ventilatory reserve at the AT > 0.70,28 was present in four cases, all of them with ILD + rPH. ΔmPAP/Δ cardiac output was 2.0 [1.5-2.8] for ILD non-PH, 3.2 [2.5-4.2] for ILD + ePH, and 5.3 [3.2-8.7] for ILD + rPH (overall, P < .001), being statistically different in the post hoc analysis for ILD + ePH vs ILD non-PH (P = .038) and for ILD + rPH vs ILD non-PH (P < .001).
Pulmonary hypertension (PH) adversely affects patient’s exercise capacity in interstitial lung disease (ILD). The impact of pulmonary vascular and right ventricular (RV) dysfunction, however, has traditionally been believed to be mild and clinically relevant principally in advanced lung disease states.
The aim of this study was to evaluate the relative contributions of pulmonary mechanics, pulmonary vascular function, and RV function to the ILD exercise limit.
Forty-nine patients with ILD who underwent resting right heart catheterization followed by invasive exercise testing were evaluated. Patients with PH at rest (ILD + rPH) and with PH diagnosed exclusively during exercise (ILD + ePH) were contrasted with ILD patients without PH (ILD non-PH).
Peak oxygen consumption was reduced in ILD + rPH (61 ± 10% predicted) and ILD + ePH (67 ± 13% predicted) compared with ILD non-PH (81 ± 16% predicted; P < .001 and P = .016, respectively). Each ILD hemodynamic phenotype presented distinct patterns of dynamic changes of pulmonary vascular compliance relative to pulmonary vascular resistance from rest to peak exercise. Peak RV stroke work index was increased in ILD + ePH (24.7 ± 8.2 g/m² per beat) and ILD + rPH (30.9 ± 6.1 g/m² per beat) compared with ILD non-PH (18.3 ± 6.4 g/m² per beat; P = .020 and P = .014). Ventilatory reserve was reduced in ILD + rPH compared with the other groups at the anaerobic threshold, but it was similar between ILD + ePH and ILD non-PH at the anaerobic threshold (0.32 ± 0.13 vs 0.30 ± 0.11; P = .921) and at peak exercise (0.70 ± 0.17 vs 0.73 ± 0.24; P = .872).
ILD with resting and exercise PH is associated with increased exercise RV work, reduced pulmonary vascular reserve, and reduced peak oxygen consumption. The findings highlight the role of pulmonary vascular and RV burden to ILD exercise limit.
Oxygen Uptake Efficiency Slope and Breathing Reserve, Not Anaerobic Threshold, Discriminate Between Patients With Cardiovascular Disease Over Chronic Obstructive Pulmonary Disease
2016, JACC: Heart Failure
Citation Excerpt :
There may be a concern that the number of patients without a measured AT influenced our results. Our results are similar to other studies in terms of numbers of COPD patients failing to achieve AT (8), and we believe representative of patients. In all cases we believe AT had not been achieved rather than being unidentifiable.
The study sought to compare the relative discrimination of various cardiopulmonary exercise testing (CPX) variables between cardiac and respiratory disease.
CPX testing is used in many cardiorespiratory diseases. However, discrimination of cardiac and respiratory dysfunction can be problematic. Anaerobic threshold (AT) and oxygen-uptake to work-rate relationship (VO₂/WR slope) have been proposed as diagnostic of cardiac dysfunction, but multiple variables have not been compared.
A total of 73 patients with chronic obstructive pulmonary disease (COPD) (n = 25), heart failure with reduced ejection fraction (HFrEF) (n = 40), or combined COPD and HFrEF (n = 8) were recruited and underwent CPX testing on a bicycle ergometer. Following a familiarization test, each patient underwent a personalized second test aiming for maximal exercise after ∼10 min. Measurements from this test were used to calculate area under the receiver-operator characteristic curve (AUC).
Peak VO₂ was similar between the 2 principal groups (COPD 17.1 ± 4.6 ml/min/kg; HFrEF 16.4 ± 3.6 ml/min/kg). Breathing reserve (AUC: 0.91) and percent predicted oxygen uptake efficiency slope (OUES) (AUC: 0.87) had the greatest ability to discriminate between COPD and HFrEF. VO₂/WR slope performed significantly worse (AUC: 0.68). VO₂ at the AT did not discriminate (AUC for AT as percent predicted peak VO₂: 0.56). OUES and breathing reserve remained strong discriminators when compared with an external cohort of healthy matched controls, and were comparable to B-type natriuretic peptide.
Breathing reserve and OUES discriminate heart failure from COPD. Despite it being considered an important determinant of cardiac dysfunction, the AT could not discriminate these typical clinical populations while the VO₂/WR slope showed poor to moderate discriminant ability. (Identifying an Ideal Cardiopulmonary Exercise Test Parameter [PVA]; NCT01162083)
Exercise-induced bronchoconstriction in school-aged children who had chronic lung disease in infancy
2013, Journal of Pediatrics
To assess for exercise-induced bronchoconstriction in 8- to 12-year-old children who had chronic lung disease (CLD) in infancy, and to evaluate the response of bronchoconstriction to bronchodilation with albuterol in comparison with preterm and term controls.
Ninety-two children, including 29 with CLD, 33 born preterm at ≤32 weeks' gestation, and 30 born at term, underwent lung spirometry before and after cycle ergometry testing and after postexercise bronchodilation with albuterol.
Doctor-diagnosed asthma and exercise-induced wheeze were reported more frequently in the CLD group than in the preterm and term groups, but only 10% were receiving a bronchodilator. There were no differences among the groups in peak minute ventilation, oxygen uptake, or carbon dioxide output at maximum exercise. After maximal exercise, predicted forced expiratory volume in 1 second (FEV₁) decreased from a mean baseline value of 81.9% (95% CI, 76.6-87.0%) to 70.8% (95% CI, 65.5-76.1%) after exercise in the CLD group, from 92.0% (95% CI, 87.2-96.8%) to 84.3% (95% CI, 79.1-89.4%) in the preterm group, and from 97.5% (95% CI, 92.5-102.6%) to 90.3% (95% CI, 85.1-95.5%) in the term group. After albuterol administration, FEV₁ increased to 86.8% (95% CI, 81.7-92.0%) in the CLD group, 92.1% (95% CI, 87.3-96.9%) in the preterm group, and 97.1% (95% CI, 92.0-102.3%) in the term group. The decrease in predicted FEV₁ after exercise and increase in predicted FEV₁ after bronchodilator use were greatest in the CLD group (−11.0% [95% CI, −18.4 to −3.6%] and 16.0% [95% CI, 8.6-23.4%], respectively; P < .005 for both), with differences of <8% in the 2 control groups.
School-age children who had CLD in infancy had significant exercise-induced bronchoconstriction that responded significantly to bronchodilation. Reversible exercise-induced bronchoconstriction is common in children who experienced CLD in infancy and should be actively assessed for and treated.
Preoperative cardiac evaluation: Mechanisms, assessment, and reduction of risk
2005, Thoracic Surgery Clinics
Utility of the Breathing Reserve Index at the Anaerobic Threshold in Determining Ventilatory-Limited Exercise in Adult Cystic Fibrosis Patients
2003, Chest
Citation Excerpt :
In contrast, this study examined a single patient population with a range of pulmonary function and, to a lesser degree, nutritional status as measured by BMI. Even the NVL group had impaired pulmonary function (albeit mild), and while the pulmonary function of the VL group was significantly lower than that of the NVL group, the FEV1 of the VL group was higher than that of the COPD population in the study by Medoff et al.5 Our study made no attempt to enroll only those subjects with extremes of pulmonary function. In fact, one might expect that if the COPD population in the study by Medoff et al5 had less severe lung disease, the optimal cutoff value obtained may have been different.
Cardiopulmonary exercise testing in cystic fibrosis (CF) patients is useful to assess functional status and prognosis. Using the current interpretation guidelines, the utility of this testing will be limited in those patients who cannot exercise to a near-maximal level. This study investigates the utility of the breathing reserve index at the anaerobic threshold (BRIAT), which is defined as minute ventilation at the anaerobic threshold (AT)/maximum voluntary ventilation (MVV), to distinguish ventilatory-limited (VL) CF patients from nonventilatory-limited (NVL) CF patients.
Exercise studies on 53 adult CF patients at baseline clinical status performed from 1993 to 1999 were reviewed, of which 40 met the inclusion criteria. The studies were performed via ramp protocol to the symptom-limited maximum on a cycle ergometer with breath-by-breath expired gas analysis. AT was determined noninvasively via the V-Slope method. The patients were classified as VL if they had abnormal spirometry findings, reduced exercise capacity, and a breathing reserve index at maximum exercise (BRImax) of ≥ 0.7. NVL patients had a normal BRImax and met the criteria for a maximal study.
VL patients (21 patients) had significantly lower FVC, FEV₁, MVV, and body mass index than NVL patients (19 patients). The BRIAT for the VL group was significantly higher than that for the NVL group (p < 0.001). Logistic regression analysis revealed that BRIAT discriminated VL patients from NVL patients better than a variety of nonexercise variables tested. The BRIAT correlated extremely well with BRImax (r = 0.89; p < 0.01), FVC (r = −0.67; p < 0.001), FEV₁ (r = −0.76; p < 0.001), and FEV₁/FVC ratio (r = −0.683; p < 0.001). A BRIAT value of 0.29 distinguished VL CF patients from NVL CF patients with 95.2% sensitivity and 84.2% specificity.
The BRIAT assessed noninvasively correlates well with commonly used measurements of pulmonary function and accurately distinguishes CF patients with and without a ventilatory limitation to exercise. The BRIAT may have utility in the interpretation of exercise studies in CF patients who are unable to exercise to a maximal level.

View all citing articles on Scopus

: Supported by a research fellowship of The Will Rogers Institute (Dr. Oelberg) and an AHA Grant-in-Aid (Dr. Systrom). Manuscript received July 9, 1997; revision accepted September 16, 1997.

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Chest

Clinical Investigations: ExerciseBreathing Reserve at the Lactate Threshold to Differentiate a Pulmonary Mechanical From Cardiovascular Limit to Exercise

Study objectives

Design

Results

Conclusions

Section snippets

Study Population

RESULTS

DISCUSSION

Clin Chest Med

Clin Chest Med

Chest

Chest

Chest

Chest

Chest

Clin Chest Med

Principles of exercise testing and interpretation

Cardiopulmonary exercise testing for evaluation of chronic cardiac failure

Am J Cardiol

Ventilatory mechanics and expiratory flow limitation during exercise in normal subjects

J Clin Invest

Exercise performance in marathon runners with airway obstruction

Med Sci Sports Exerc

The ventilatory capacity of patients with chronic airways obstruction

Clin Sci

Pattern of breathing during exercise in patients with interstitial lung disease

Thorax

Lung volumes and expiratory flow limitation during exercise in interstitial lung disease

J Appl Physiol

Improved detection of lactate threshold during exercise using a log-log transformation

J Appl Physiol

Reductions in exercise lactic acidosis and ventilation as a result of exercise training in patients with obstructive lung disease

Am Rev Respir Dis

On-line computer analysis and breath-by-breath graphical display of exercise function tests

J Appl Physiol

Clinical Investigations: Exercise
Breathing Reserve at the Lactate Threshold to Differentiate a Pulmonary Mechanical From Cardiovascular Limit to Exercise