Ventilatory Equivalents Research Articles

Oral versus Nasal Breathing during Moderate to High Intensity Submaximal Aerobic Exercise

Introduction: When comparing oral breathing versus nasal breathing, a greater volume of air can be transported through the oral passageway but nasal breathing may also have benefits at submaximal exercise intensities. Purpose: The purpose of this study was to determine breathing efficiency during increasing levels of submaximal aerobic exercise. Methods: Nineteen individuals (males N=9, females N=10) completed a test for maximal oxygen consumption (VO2max) and on separate days 4-min treadmill runs at increasing submaximal intensities (50%, 65%, and 80% of VO2max) under conditions of oral breathing or nasal breathing. Respiratory (respiration rate [RR], pulmonary ventilation [VE]), metabolic (oxygen consumption [VO2], carbon dioxide production [VCO2]) and efficiency measures (ventilatory equivalents for oxygen [Veq×O2-1] and carbon dioxide [Veq×CO2-1] were obtained. Data were analyzed utilizing a 2 (sex) x 2 (condition) x3 (intensity) repeated measures ANOVA with significance accepted at p≤0.05. Results: Significant interactions existed between breathing mode and intensity such that oral breathing resulted in greater RR, VE, VO2, and VCO2 at all three submaximal intensities (p<.05). Veq×O2-1 and Veq×CO2-1 presented findings that nasal breathing was more efficient than oral breathing during the 65% and 80% VO2max intensities (p<0.05). Conclusion: Based on this analysis, oral breathing provides greater respiratory and metabolic volumes during moderate and moderate-to-high submaximal exercise intensities, but may not translate to greater respiratory efficiency. However when all variables are considered together, it is likely that oral breathing represents the more efficient mode, particularly at higher exercise intensities.

Physiologic Determinants of Exercise Capacity in Pulmonary Langerhans Cell Histiocytosis: A Multidimensional Analysis.

BackgroundReduced exercise capacity severely impacts quality of life in pulmonary Langerhans cell histiocytosis. Ascertaining mechanisms that impair exercise capacity is necessary to identify targets for symptomatic treatments.MethodsDyspnea, pulmonary function tests and cardiopulmonary exercise test were analysed in 62 study participants. Data were compared between subjects with impaired and normal aerobic capacity (V’O2 peak less than 84% versus 84% predicted or more). Data were reduced using a principal component analysis. Multivariate analysis included V’O2 peak as the dependent variable and principal components as covariates.ResultsV’O2 peak was reduced in 44 subjects (71%). Subjects with impaired aerobic capacity presented: (i) decreased FEV1, FVC, FEV1/FVC, DLCO and DLCO/VA and increased AaDO2, (ii) increased ventilatory equivalents at ventilatory threshold, VD/VT peak, AaDO2 peak and PaCO2 peak and decreased ventilatory reserve and PaO2 peak. There was no difference between groups in dyspnea scores. Principal component analysis extracted 4 principal components interpreted as follows: PC1: gas exchange; PC2: “pseudorestriction”; PC3: exercise-induced hyperpnea; PC4: air trapping. Multivariate analysis explained 65% of V’O2 peak. The 4 principal components were independently associated with V’O2 peak (βcoefficients: PC1: 9.3 [4.6; 14], PC2: 7.5 [3; 11.9], PC3: -5.3 [-9.6;-1.], PC4: -9.8 [-14,9;-4.7]).ConclusionImpaired exercise capacity is frequent in pulmonary Langerhans cell histiocytosis. It is mainly caused by pulmonary changes but is not associated with increased dyspnea intensity. Therefore, treating the lung represents a relevant approach for improving exercise capacity, even in patients experiencing mild dyspnea.

Assessment of Maximum Aerobic Capacity and Anaerobic Threshold of Elite Ballet Dancers.

An athlete's cardiorespiratory profile, maximal aerobic capacity, and anaerobic threshold is affected by training regimen and competition demands. The present study aimed to ascertain whether there are company rank differences in maximal aerobic capacity and anaerobic threshold in elite classical ballet dancers. Seventy-four volunteers (M 34, F 40) were recruited from two full-time professional classical ballet companies. All participants completed a continuous incremental treadmill protocol with a 1-km/hr speed increase at the end of each 1-min stage until termination criteria had been achieved (e.g., voluntary cessation, respiratory exchange ratio <1.15, HR ±5 bpm of estimated HRmax). Peak VO2 (5-breathe smooth) was recorded and anaerobic threshold calculated using ventilatory curve and ventilatory equivalents methods. Statistical analysis reported between-subject effects for gender (F1,67=35.18, p<0.001) and rank (F1,67=8.67, p<0.001); post hoc tests reported soloists (39.5±5.15 mL/kg/min) as having significantly lower VO2 peak than artists (45.9±5.75 mL/kg/min, p<0.001) and principal dancers (48.07±3.24 mL/kg/min, p<0.001). Significant differences in anaerobic threshold were reported for age (F1,67=7.68, p=0.008) and rank (F1,67=3.56, p=0.034); post hoc tests reported artists (75.8±5.45%) having significantly lower anaerobic threshold than soloists (80.9±5.71, p<0.01) and principals (84.1±4.84%, p<0.001). The observed differences in VO2 peak and anaerobic threshold between the ranks in ballet companies are probably due to the different rehearsal and performance demands.

VENTILAORY CHANGES AFTER INSPIRATORY MUSCLE TRAINING IN CHRONIC HEART FAILURE PATIENTS

Introduction: inspiratory muscle training (IMT) improves exercise capacity and ventilatory responses to exercise in CHF patients with inspiratory muscle weakness (IMW). Aim of Work: to investigate the effect of inspiratory muscle training (IMT) with comprehensive cardiac rehabilitation (CR) program (aerobic and resisted exercise training) on ventilatory changes in chronic heart failure patients. Materials and Methods: Forty eligible male patients with chronic heart failure secondary to ischemic heart disease but only thirty of them completed the study. Their ages ranged from 50-60 years old .They were randomly assigned to 6 months of aerobic exercise, resisted exercise plus IMT (n=15) or to aerobic exercise plus resisted exercise only (n=15), Before and after intervention, the following measures were obtained: maximal inspiratory muscle pressure (PImax), ventilatory equivalent of CO2 at anaerobic threshold of cardiopulmonary exercise testing. Result: Compared aerobic exercise (AE) + IMT to AE resulted in additional significant difference in EqCO2 (25.43% vs 16.77%) and in PImax (14.81%. vs 34.94 %.). Conclusion: This study demonstrates that the addition of IMT to AE results in improvement in ventilator responses to exercise in selected patients with CHF and IMW

Small Airway Dysfunction and Abnormal Exercise Responses. A Study in Coal Miners.

Coal mine dust exposure can cause symptoms and loss of lung function from multiple mechanisms, but the roles of each disease process are not fully understood. We investigated the implications of small airway dysfunction for exercise physiology among a group of workers exposed to coal mine dust. Twenty coal miners performed spirometry, first breathing air and then helium-oxygen, single-breath diffusing capacity, and computerized chest tomography, and then completed cardiopulmonary exercise testing. Six participants meeting criteria for small airway dysfunction were compared with 14 coal miners who did not. At submaximal workload, miners with small airway dysfunction used a higher proportion of their maximum voluntary ventilation and had higher ventilatory equivalents for both O2 and CO2. Regression modeling indicated that inefficient ventilation was significantly related to small airway dysfunction but not to FEV1 or diffusing capacity. At the end of exercise, miners with small airway dysfunction had 27% lower O2 consumption. Small airway abnormalities may be associated with important inefficiency of exercise ventilation. In dust-exposed individuals with only mild abnormalities on resting lung function tests or chest radiographs, cardiopulmonary exercise testing may be important in defining causes of exercise intolerance.

Hemodynamic and ventilatory responses during exercise in chronic thromboembolic disease

BackgroundPatients with chronic thromboembolic disease (CTED) may suffer from exercise intolerance without pulmonary hypertension at rest. Pulmonary endarterectomy (PEA) for symptomatic CTED results in improvement of symptoms and quality of life. Neither the pathophysiology of the exercise limitation nor the underlying mechanisms of the PEA-induced improvement have been studied previously. ObjectivesWe studied hemodynamic and ventilatory responses upon exercise in 14 patients with CTED. After 1 year, we studied the underlying physiologic mechanisms of the PEA-induced symptomatic improvement. MethodsCardiopulmonary exercise testing (CPET) was performed during right heart catheterization, and noninvasive CPET was performed 1 year postoperatively. ResultsDuring exercise, we observed abnormal pulmonary vascular responses, that is, a steep mean pulmonary artery pressure/cardiac output (2.7 ± 1.2 mm Hg·min·L−1), and low pulmonary vascular compliance (2.8 ± 1.1 mL·mm Hg−1); mean pulmonary artery pressure/cardiac output slope correlated with dead-space ventilation (r = 0.586; P = .028) and ventilatory equivalents for carbon dioxide slope (r = .580; P = .030). Postoperatively, the improvement observed in exercise capacity was related to improvements in CPET-derived parameters pointing to restoration of right ventricle stroke volume response (oxygen pulse: 11.7 ± 3.1 to 13.3 ± 3.3; P = .027; heart rate response: 80.9 ± 12.4 to 72.0 ± 5.7; P = .003); and, indicating improved ventilatory efficiency, the ventilatory equivalents for carbon dioxide slope decreased from 38.2 ± 3.6 to 32.8 ± 7.0 (P = .014). ConclusionsPatients with CTED showed an abnormal pulmonary vascular response to exercise and a decreased ventilatory efficiency. Responses after PEA point to restoration of right ventricle stroke volume response and ventilatory efficiency.

The impact of neoadjuvant chemotherapy on cardiopulmonary physical fitness in gastro-oesophageal adenocarcinoma.

Introduction Operable oesophagogastric adenocarcinoma management in the UK includes three cycles of neoadjuvant chemotherapy (NAC) followed by resection. Determination of oxygen uptake at the anaerobic threshold (AT) with cardiopulmonary exercise testing (CPET) is used to objectively measure cardiorespiratory reserve. Oxygen uptake at AT predicts perioperative risk, with low values associated with increased morbidity. Previous studies indicate NAC may have a detrimental impact on cardiorespiratory reserve. Methods CPET was completed by 30 patients before and after a standardised NAC protocol. The ventilatory AT was determined using the V-slope method, and the peak oxygen uptake and ventilatory equivalents for carbon dioxide measured. Median AT before and after chemotherapy was compared using a paired Student's t-test. Results Median oxygen uptake at AT pre- and post-NAC was 13.9±3.1 ml/kg/min and 11.5±2.0 ml/kg/min, respectively. The mean decrease was 2.4 ml/kg/min (95% confidence interval [CI] 1.3-3.85; p<0.001). Median peak oxygen delivery also decreased by 2.17 ml/kg/min (95% CI 1.02-3.84; p=0.001) after NAC. Ventilatory equivalents were unchanged. Conclusions This reduction in AT objectively quantifies a decrease in cardiorespiratory reserve after NAC. Patients with lower cardiorespiratory reserve have increased postoperative morbidity and mortality. Preventing this decrease in cardiorespiratory reserve during chemotherapy, or optimising the timing of surgical resection after recovery of AT, may allow perioperative risk-reduction.

Oxygen Uptake Efficiency Slope Predicts Major Cardiac Events in Patients With End-Stage Heart Failure

IntroductionOxygen uptake efficiency slope (OUES) has been shown as a predictor of stable heart failure (HF) survival. However, there is a lack of evidence for end-stage HF. ObjectivesWe aimed to investigate the prognostic value of OUES in end-stage HF patients. MethodsThe study design was a retrospective cohort. End-staged HF patients who had cardiopulmonary exercise testing (CPET) for evaluation between 2004 and 2009 were included. The primary outcomes were cardiac death and heart transplantation. The independent survival predictors were determined using Cox regression hazard model adjusted for demographics, New York Heart Association (NYHA) classification, medication, and left ventricular ejection fraction (LVEF). The Kaplan-Meier survival curves and log-rank test were used. Probability values less than .05 were considered significant. ResultsMean age of the 128 patients was 50 ± 12 years and 93 were male. Mean LVEF was 23% ± 9%. Forty-three subjects suffered cardiac events (5 cardiac deaths and 38 urgent heart transplantations) during the 2-year follow-up period. Cox regression indicated that OUES and diuretics were significant predictors of 2-year survival, although peak oxygen uptake and ventilatory equivalent of carbon dioxide were not. Patients with high OUES (≥1.6) had a higher survival rate (P < .001; odds ratio [OR], 13.10; 95% confidence interval [CI], 3.30–58.63). The Kaplan-Meier curves show survival was significantly higher in those with OUES ≥1.6. ConclusionsOUES might be an aid in prognosis of patients with end-stage HF and useful in the assessment of patients unable to perform maximal exercise testing.

Respiratory pattern, thoracoabdominal motion and ventilation in chronic airway obstruction

Patients with chronic obstructive pulmonary disease (COPD) present abnormal respiratory mechanics, but its relation to ventilation variables at rest is not fully understood. We evaluated breathing pattern, thoracoabdominal motion, and ventilation in moderate and severe COPD patients by means of respiratory inductive plethysmograph and analysis of respiratory metabolism in semirecumbent position at rest. Diaphragmatic movement was measured using radiographs. COPD patients showed an increase in mean inspiratory flow, minute ventilation, dead space ventilation, oxygen and carbon dioxide ventilatory equivalents and reduction of respiratory times and pulse oxymetry. These findings were more pronounced in severe COPD. Changes in ventilatory efficiency were correlated with decreased respiratory times, reduced diaphragmatic movement, and lower oxygen uptake. Rapid shallow breathing and reduced diaphragmatic movement have led to ventilatory inefficiency without changes in thoracoabdominal motion.

Exercise-related risk at anaerobic threshold in patients with chronic obstructive pulmonary disease

To investigate the exercise-related risk at anaerobic threshold(AT) in patients with chronic obstructive pulmonary disease(COPD). Sixty two patients [men 56, women 6, aged (66±8) yr] with stable COPD in Beijing Friendship Hospital during 2013-2014, participated in this study. Incremental symptom-limited cardiopulmonary exercise test was performed on cycle ergometer. The AT was determined using the V-Slope technique and ventilatory equivalents for carbon dioxide and oxygen. Symptoms, 10-lead electrocardiogram, oxygen saturation by pulse oximetry(SpO(2)) were monitored during exercise. The AT, detectable in 53 patients, occurred at (68±10)% of peak oxygen uptake(peak VO(2)). The SpO(2) was in the safe range (94±2) % and the respiratory reserve was relatively high at AT (i.e. 48%). High-intensity exercise training can be performed in patients with moderate-to- severe COPD without resting oxygen desaturation.

Heart rate variability to assess ventilatory thresholds in professional basketball players

PurposeThe aim of this study was to determine if heart rate variability (HRV) during incremental test could be used to estimate ventilatory threshold (VT) in professional basketball players, with sufficient precision to be used in their training. Furthermore, the second aim was to analyse the association between HRV and 3 methods of VT determination by gas analysis. MethodsTwenty-four professional basketball players (age: 23.4 ± 4.9 years; height: 195.4 ± 9.8 cm; body mass: 92.2 ± 11.9 kg) performed an incremental running test to exhaustion. First ventilatory threshold (VT1) was determined by ventilatory equivalent (VE) and HRV and second ventilatory threshold (VT2) was determined by 3 methods of gases analysis (V-slope, VE and gas exchange ratio (R), and HRV). Pearson's coefficient (r) was used to detect differences between data and the strength of each relationship. The mean of absolute differences and Bland–Altman analysis were used to evaluate whether there was agreement. ResultsThe results showed no significant differences in HR and oxygen consumption (VO2) at VT1 between the 2 methods. Furthermore, no significant differences among the methods of gases analysis and HRV were observed in speed, HR, and VO2 at VT2. Moreover, VTs estimated using HRV and gas methods were significantly correlated. Correlation in HR values was higher between R and HRV (r = 0.96) and VE and HRV (r = 0.96) than V-slope and HRV (r = 0.90). ConclusionThese findings provide a practical, inexpensive approach for evaluating specific training loads when determining VT2 in basketball players. Therefore, HRV is an alternative method to determine VT2 without the application of expensive technology that limits its use to laboratories.

The lactate and ventilatory thresholds in resistance training.

This study was designed to identify the lactate threshold (LT) and first ventilatory threshold (VT1 ) in a graded resistance half-squat test and determine whether both thresholds are produced at the same workload. A further goal was to compare the visual inspection and algorithm adjustment methods of detecting both thresholds during graded resistance exercise. Twenty-four young men completed two test sessions 48h apart; (i) the one-repetition maximum (1RM) was determined, (ii) an incremental load test was performed to locate LT and VT1 . VT1 was calculated in three different ways based on pulmonary ventilation, the ventilatory equivalent of oxygen or the end-tidal oxygen pressure (as VT1 -VE, VT1 -VE·VO2-1 or VT1 -PetO2, respectively). LT and VT1 were located at the same intensity of exercise during the incremental load test. Using the algorithm method, the LT and VT1 -VE were estimated at 24·8±4·8% 1RM (50·6±10·5kg) and 23·7±4·8% 1RM (48·4± 10·0kg), respectively; the difference between the two values being non-significant (P=0·127). In addition, positive correlation was observed between the two thresholds (r=0·761; P<0·001; intraclass correlation coefficient (ICC) (0·864). The visual inspection and algorithm adjustment methods provided similar LT and VT1 values (r>0·796; ICC>0·885). The LT and VT1 were readily located during the incremental load half-squat test at similar workloads using both the visual inspection and algorithm adjustment methods. Both thresholds served to define two physiological stages (I, II) corresponding to the zones described for endurance exercise. Thus, both LT and VT1 could be used to prescribe the same intensity of resistance half-squat exercise.

Ventilation Rates during the Aggregate Daytime Activities of Working Females in Hospitals: Data before their Pregnancy and at their 9th, 22nd and 36th Week of Gestation

Working females in hospitals may inhale pharmaceutical agents, chirurgical smokes, organic solvents, bacteria and/or viruses. These inhaled agents may generate adverse effects in gravid females, their embryo or fetus. Therefore, minute ventilation rates (VE) during the aggregate daytime activities of under (n=68), normal (n=268), overweight (n=42), obese class 1 (n=68) and classes 2-3 (n=51) females working in hospitals were determined before and during their pregnancy using published measurements of energy expenditures. For comparison purposes, VE values were also calculated for the same females at rest. Activity energy expenditures were based on disappearance rates of oral doses of water isotopes (i.e. 2H2O, H2 18O) monitored in urine samples of free-living hospital workers during 175 days by gas-isotope-ratio mass spectrometry. Basal energy expenditures were obtained by indirect calorimetry, whereas energy costs for pregnancy were measured in a room calorimeter. Sleep durations (7.30 ± 1.59 to 8.09 ± 1.25 hours/ day; mean ± standard deviation) and ventilatory equivalents (31.7 ± 0.93 to 39.3 ± 3.3 L of air inhaled/L of oxygen consumed) during pregnancy were determined and integrated into the calculation process. Based on VE percentiles some non-pregnant and pregnant female workers inhale more air (thus more air pollutants), than the default VE value of 20.83 L/min (i.e. 10 m3 in an 8 hour workday) notably used for calculations of hygienic standards for airborne xenobiotics. Highest 99th percentiles of 34.28, 29.27 26.49 and 29.52 L/min were found in obese classes 2-3 female workers, before their pregnancy and at their 9th, 22nd and 36th week of gestation, respectively. Considering what precedes and the fact that the human chorionic gonadotropin is detected in the blood or urine samples of women after the implantation of their blastocyst, which occurs many days after fertilization, the non-exposure of female workers to teratogenic agents in hospitals is recommended before and during their pregnancy. The same applies for the exposure to carcinogens which may generate procarcinogenic DNA damage in the fetus.

Exercise capacity in adult patients after Fontan procedure. (RCD code: IV-5B.1)

Background: The aim of Fontan procedure is to restore a balance between pulmonary and systemic circulation and improve or nearly normalize arterial saturation in patients with functionally univentricular heart. Nevertheless, due to the lack of subpulmonary pump, the circulatory system becomes haemodynamically less efficient, what can lead to the impairment of exercise capacity. Aim: The aim of the study was to investigate exercise capacity by means of cardiopulmonary exercise test and pulmonary function tests, of 37 adult Fontan patients with regard to the time passed from the index procedure. The patients were divided into 3 groups: group I – up to 15 years post procedure; group II – 16–20 years, group III – more than 20 years after Fontan procedure). Results: 37 Fontan patients (mean age was 24.4 ±5.7 years, 40% of women) were enrolled in the study. The mean postoperative time was 19.4 ±5.1 (13–30) years. Mean, peak oxygen consumption (VO2peak) was 22.7 ±7.1 ml/kg/min (64.2 ±18.5% of predicted value). According to postoperative time a significant increase of ventilatory equivalent of carbon dioxide (VE/VCO2) (p = 0.033) and significant decrease of forced expiratory volume in 1 s/ vital capacity (FEV1%VC) between group 2 and 3 (p = 0.026) were observed. Additionally, the age of the patients correlated negatively with and heart rate (HR) (r = -0.360, p <0.05) and peak oxygen consumption (VO2peak) (r = -0,337, p < 0.05). Moreover, age at Fontan operation and time after Fontan procedure was related to ventilator equivalent of oxygen (VE/VO2) (r = -0,343, p <0.05, and r = 0.393, p <0.05). Single ventricle ejection fraction (SVEF) and atrioventricular regurgitation degree did not corresponded with cardiopulmonary exercise test (CPET) values. Conclusions: Results highlight the complex problem of diminished exercise capacity of Fontan patients depending on the time passed from the procedure. Exercise tolerance deteriorates in time: VE/VCO2 increases, FEV1/VC markedly lowers in a group of Fontan patients at 20 years follow-up. JRCD 2016; 2 (8): 254–258

Preserved cardiorespiratory function and NT-proBNP levels before and during exercise in patients with recent onset of rheumatoid arthritis: the clinical challenge of stratifying the patient cardiovascular risks.

Rheumatoid arthritis (RA) is associated with an increased risk of myocardial infarction and congestive heart failure. In RA patients, elevated NT-proBNP levels have been reported to be a prognostic marker of left ventricular dysfunction. In this study, we evaluated cardiorespiratory functional capacity and NT-proBNP levels before and during cardiopulmonary exercise test in early RA (ERA) patients. Twenty ERA patients and 10 healthy controls were studied by color Doppler echocardiography to evaluate ventricular systolic and diastolic function. Arterial stiffness and wave reflections were quantified non-invasively using applanation tonometry of the radial artery. Cardiopulmonary treadmill test was performed to measure peak VO2 and VE/VCO2 parameters. NT-proBNP plasma levels were measured before and at the exercise peak during cardiopulmonary exercise. The peak oxygen uptake [VO2 (ml/min/kg)], the ventilatory equivalents for carbon dioxide (EqCO2), respiratory exchange ratio and arterial stiffness were similar between patients and controls during cardiopulmonary exercise test. Basal and peak cardiopulmonary exercise NT-proBNP plasma levels were comparable in ERA patients with respect to healthy controls. When we analyzed patients according to disease characteristics and cardiovascular risk factors, ERA patients with high disease activity, BMI>25kg/m2 and ACPA positivity presented significantly higher baseline and exercise peak NT-proBNP levels. Cardiorespiratory function is preserved in patients with recent onset of rheumatoid arthritis. The increased basal and exercise peak NT-proBNP plasma levels in patients with negative disease prognostic factors represent a possible marker to stratify the cardiovascular risk in patients with early rheumatoid arthritis.

Pulmonary vascular function and exercise capacity in black sub-Saharan Africans.

Sex and age affect the pulmonary circulation. Whether there may be racial differences in pulmonary vascular function is unknown. Thirty white European Caucasian subjects (15 women) and age and body-size matched 30 black sub-Saharan African subjects (15 women) underwent a cardiopulmonary exercise test and exercise stress echocardiography with measurements of pulmonary artery pressure (PAP) and cardiac output (CO). A pulmonary vascular distensibility coefficient α was mathematically determined from the natural curvilinearity of multipoint mean PAP (mPAP)-CO plots. Maximum oxygen uptake (V̇o2max) and workload were higher in the whites, while maximum respiratory exchange ratio and ventilatory equivalents for CO2 were the same. Pulmonary hemodynamics were not different at rest. Exercise was associated with a higher maximum total pulmonary vascular resistance, steeper mPAP-CO relationships, and lower α-coefficients in the blacks. These differences were entirely driven by higher slopes of mPAP-CO relationships (2.5 ± 0.7 vs. 1.4 ± 0.7 mmHg·l(-1)·min; P < 0.001) and lower α-coefficients (0.85 ± 0.33 vs. 1.35 ± 0.51%/mmHg; P < 0.01) in black men compared with white men. There were no differences in any of the hemodynamic variables between black and white women. In men only, the slopes of mPAP-CO relationships were inversely correlated to V̇o2max (P < 0.01). Thus the pulmonary circulation is intrinsically less distensible in black sub-Saharan African men compared with white Caucasian Europeans men, and this is associated with a lower exercise capacity. This study did not identify racial differences in pulmonary vascular function in women.

Exercise End-Tidal CO2 Predicts Central Sleep Apnea in Patients With Heart Failure

Increased CO2 chemosensitivity and augmented exercise ventilation are characteristic of patients with heart failure (HF) with central sleep apnea (CSA). The aim of this study was to test the hypothesis that decreased end-tidal CO2 by cardiopulmonary exercise testing predicts CSA in patients with HF. Consecutive ambulatory patients with New York Heart Association II to III HF were prospectively evaluated by CO2 chemosensitivity by rebreathe, cardiopulmonary exercise testing, and polysomnography (PSG). Subjects were classified as having either CSA (n = 20) or no sleep apnea (n = 13) by PSG; a central apnea-hypopnea index (AHI) ≥ 5 was used to define CSA. Subgroups were compared by t test or Mann-Whitney test and data summarized as mean ± SD. P < .05 was considered significant. At rest, subjects with CSA had higher central CO2 chemosensitivity (Δminute ventilation [V.e]/Δpartial pressure of end-tidal CO2 [Petco2], 2.3 ± 1.0 L/min/mm Hg vs 1.6 ± 0.4 L/min/mm Hg, P = .02) and V.e (15 ± 7 L/min vs 10 ± 3 L/min, P = .02) and lower Petco2 (31 ± 4 mm Hg vs 35 ± 4 mm Hg, P < .01) than control subjects. At peak exercise, the ventilatory equivalents per expired CO2 (V.e/V.co2) was higher (43 ± 9 vs 33 ± 6, P < .01) and Petco2 lower (29 ± 6 mm Hg vs 36 ± 5 mm Hg, P < .01) in subjects with CSA. In addition, CO2 chemosensitivity, peak exercise V.e/V.co2, and Petco2 were independently correlated with CSA severity as quantified by the AHI (P < .05). Peak exercise Petco2 was most strongly associated with CSA (OR, 1.29; 95% CI, 1.08-1.54; P = .01; area under the curve, 0.88). In patients with HF and CSA, ventilatory drive is increased while awake at rest and during exercise and associated with heightened CO2 chemosensitivity and decreased arterial CO2 set point.

PWE-080 Is cardiopulmonary exercise testing prior to hepatectomy useful?

Introduction Liver resection is a major operation with significant morbidity and mortality, and accurate pre-operative assessment of risk is important. Cardiopulmonary exercise testing (CPX) is used increasingly before major abdominal surgery, although its usefulness prior to hepatectomy is unclear. We wished to evaluate the role of CPX testing prior to liver resection. Method Prospectively collected data were extracted from the HPB unit database. The study group excluded patients with chronic liver disease and biliary obstruction. CPX testing was introduced in February 2008, initially selectively but after November 2013 was used in all patients undergoing liver resection. Standard CPX and operative parameters were retrieved. Operative complications were classified according to the Clavien-Dindo system and grade 3–5 complications considered significant. Multi-variate methods were used to assess potential associations between pre-operative CPX parameters and operative complications. Results Pre-operative CPX was performed on 183 occasions. Grade 3, 4 and 5 complications were suffered by 17, 38 and 3% of patients, respectively. A weak association was noted between increasing ventilatory equivalents for CO2(VE/CO2), the risk of Grade 3–5 complications (Odds ratio = 1.11, p = 0.015) and length of post-operative stay (p = 0.004). No association was noted between any other CPX variable and operative outcome. Conclusion With the exception of VE/CO2,CPX test parameters did not predict the development of post-operative complications. It is likely that the majority of complications suffered after liver resection relate to technical aspects of the operation and are not associated with cardio-respiratory function. Disclosure of interest None Declared.

Abnormal ventilatory response to exercise in young adults operated for ventricular septal defect in early childhood: A long-term follow-up

BackgroundVentricular septal defects (VSDs) are normally closed in early childhood, and postsurgical physical capacity is generally considered normal. Despite an increasing understanding of late cardiac morbidity among these patients, long-term pulmonary function remains to be investigated. Therefore, the aim of this prospective follow-up study was to describe ventilatory function during exercise in VSD-repaired adults operated in early life. MethodsWe tested cardiopulmonary exercise capacity in 27 patients and 30 healthy control subjects on an ergometer cycle. Each test was preceded by a standard spirometry, and the exercise test was performed as a maximal incremental test. Pulmonary ventilation and gas exchange were simultaneously measured breath-by-breath with minute ventilation at peak exercise as our main endpoint. ResultsIn the VSD-group the median surgical age was 1.9 (95% CI 1.1–2.8years) and the mean age at time of examination was 21.1±3.1years in the VSD-group vs. 21.2±2.5years in the control group. Mean minute ventilation at peak exercise was significantly lower in the VSD-group compared with the controls: 1.4±0.4L/kg/min vs. 1.8±0.4L/kg/min, p<0.01. Likewise, mean oxygen uptake was reduced: 38.0±8.2ml/kg/min in the VSD-cohort vs. 47.9±6.5ml/kg/min among controls, p<0.01. In terms of breath rate and ventilatory equivalents (O2 and CO2) there were no differences between the groups. ConclusionsPatients with a surgically closed VSD have a markedly abnormal ventilatory response to exercise with significantly reduced minute ventilation despite a similar breath rate. With a follow-up of almost two decades our finding most certainly reflects an unknown but persisting abnormality.

Long-term effects of graduated compression stockings on cardiorespiratory performance.

The use of graduated compression stockings (GCS) in sport has been increasing in the last years due to their potential positive effects for athletes. However, there is little evidence to support whether these types of garments actually improve cardiorespiratory performance. The aim of this study was to examine the cardiorespiratory responses of GCS during running after three weeks of regular use. Twenty recreational runners performed three tests on different days: test 1) – a 5-min maximal effort run in order to determine the participants’ maximal aerobic speed; and tests 2) and 3) – a fatigue running test of 30 minutes at 80% of their maximal aerobic speed with either GCS or PLACEBO stockings at random. Cardiorespiratory parameters (minute ventilation, heart rate, relative oxygen consumption, relative carbon dioxide production, ventilatory equivalents for oxygen and carbon dioxide, and oxygen pulse) were measured. Before each test in the laboratory, the participants trained with the randomly assigned stockings (GCS or PLACEBO) for three weeks. No significant differences between GCS and PLACEBO were found in any of the cardiorespiratory parameters. In conclusion, the present study provides evidence that running with GCS for three weeks does not influence cardiorespiratory parameters in recreational runners.