Exercise intolerance in comorbid COPD and heart failure: the role of impaired aerobic function.

Impaired aerobic function is a potential mechanism of exercise intolerance in patients with combined cardiorespiratory disease. We investigated the pathophysiological and sensory consequences of a low change in oxygen uptake (ΔV'O2 )/change in work rate (ΔWR) relationship during incremental exercise in patients with coexisting chronic obstructive pulmonary disease (COPD) and systolic heart failure (HF).After clinical stabilisation, 51 COPD-HF patients performed an incremental cardiopulmonary exercise test to symptom limitation. Cardiac output was non-invasively measured (impedance cardiography) in a subset of patients (n=18).27 patients presented with ΔV'O2 /ΔWR below the lower limit of normal. Despite similar forced expiratory volume in 1 s and ejection fraction, the low ΔV'O2 /ΔWR group showed higher end-diastolic volume, lower inspiratory capacity and lower transfer factor compared to their counterparts (p<0.05). Peak WR and peak V'O2 were ∼15% and ∼30% lower, respectively, in the former group: those findings were associated with greater symptom burden in daily life and at a given exercise intensity (leg discomfort and dyspnoea). The low ΔV'O2 /ΔWR group presented with other evidences of impaired aerobic function (sluggish V'O2 kinetics, earlier anaerobic threshold) and cardiocirculatory performance (lower oxygen pulse, lower stroke volume and cardiac output) (p<0.05). Despite similar exertional hypoxaemia, they showed worse ventilatory inefficiency and higher operating lung volumes, which led to greater mechanical inspiratory constraints (p<0.05).Impaired aerobic function due to negative cardiopulmonary-muscular interactions is an important determinant of exercise intolerance in patients with COPD-HF. Treatment strategies to improve oxygen delivery to and/or utilisation by the peripheral muscles might prove particularly beneficial to these patients.

Physiological and clinical relevance of exercise ventilatory efficiency in COPD.

Exercise ventilation (V'E) relative to carbon dioxide output (V'CO2 ) is particularly relevant to patients limited by the respiratory system, e.g. those with chronic obstructive pulmonary disease (COPD). High V'E-V'CO2 (poor ventilatory efficiency) has been found to be a key physiological abnormality in symptomatic patients with largely preserved forced expiratory volume in 1 s (FEV1). Establishing an association between high V'E-V'CO2 and exertional dyspnoea in mild COPD provides evidence that exercise intolerance is not a mere consequence of detraining. As the disease evolves, poor ventilatory efficiency might help explaining "out-of-proportion" breathlessness (to FEV1 impairment). Regardless, disease severity, cardiocirculatory co-morbidities such as heart failure and pulmonary hypertension have been found to increase V'E-V'CO2 In fact, a high V'E-V'CO2 has been found to be a powerful predictor of poor outcome in lung resection surgery. Moreover, a high V'E-V'CO2 has added value to resting lung hyperinflation in predicting all-cause and respiratory mortality across the spectrum of COPD severity. Documenting improved ventilatory efficiency after lung transplantation and lung volume reduction surgery provides objective evidence of treatment efficacy. Considering the usefulness of exercise ventilatory efficiency in different clinical scenarios, the V'E-V'CO2 relationship should be valued in the interpretation of cardiopulmonary exercise tests in patients with mild-to-end-stage COPD.

Exercise Ventilation in COPD: Influence of Systolic Heart Failure.

Systolic heart failure is a common and disabling co-morbidity of chronic obstructive pulmonary disease (COPD) which may increase exercise ventilation due to heightened neural drive and/or impaired pulmonary gas exchange efficiency. The influence of heart failure on exercise ventilation, however, remains poorly characterized in COPD. In a prospective study, 98 patients with moderate to very severe COPD [41 with coexisting heart failure; 'overlap' (left ventricular ejection fraction < 50%)] underwent an incremental cardiopulmonary exercise test (CPET). Compared to COPD, overlap had lower peak exercise capacity despite higher FEV1. Overlap showed lower operating lung volumes, greater ventilatory inefficiency and larger decrements in end-tidal CO2 (PETCO2) (P < 0.05). These results were consistent with those found in FEV1-matched patients. Larger areas under receiver operating characteristic curves to discriminate overlap from COPD were found for ventilation ([Formula: see text]E)-CO2 output [Formula: see text]CO2) intercept, [Formula: see text]E-[Formula: see text]CO2 slope, peak [Formula: see text]E/[Formula: see text]CO2 ratio and peak PETCO2. Multiple logistic regression analysis revealed that [Formula: see text]CO2 intercept ≤ 3.5 L/minute [odds ratios (95% CI) = 7.69 (2.61-22.65), P < 0.001] plus [Formula: see text]E-[Formula: see text]CO2 slope ≥ 34 [2.18 (0.73-6.50), P = 0.14] or peak [Formula: see text]E/[Formula: see text]CO2 ratio ≥ 37 [5.35 (1.96-14.59), P = 0.001] plus peak PETCO2 ≤ 31 mmHg [5.73 (1.42-23.15), P = 0.01] were indicative of overlapping. Heart failure increases the ventilatory response to metabolic demand in COPD. Variables reflecting excessive ventilation might prove useful to assist clinical interpretation of CPET responses in COPD patients presenting heart failure as co-morbidity.

Heart Failure Impairs Muscle Blood Flow and Endurance Exercise Tolerance in COPD.

Heart failure, a prevalent and disabling co-morbidity of COPD, may impair cardiac output and muscle blood flow thereby contributing to exercise intolerance. To investigate the role of impaired central and peripheral hemodynamics in limiting exercise tolerance in COPD-heart failure overlap, cycle ergometer exercise tests at 20% and 80% peak work rate were performed by overlap (FEV1 = 56.9 ± 15.9% predicted, ejection fraction = 32.5 ± 6.9%; N = 16), FEV1-matched COPD (N = 16), ejection fraction-matched heart failure patients (N = 15) and controls (N = 12). Differences (Δ) in cardiac output (impedance cardiography) and vastus lateralis blood flow (indocyanine green) and deoxygenation (near-infrared spectroscopy) between work rates were expressed relative to concurrent changes in muscle metabolic demands (ΔO2 uptake). Overlap patients had approximately 30% lower endurance exercise tolerance than COPD and heart failure (p < 0.05). ΔBlood flow was closely proportional to Δcardiac output in all groups (r = 0.89-0.98; p < 0.01). Overlap showed the largest impairments in Δcardiac output/ΔO2 uptake and Δblood flow/ΔO2 uptake (p < 0.05). Systemic arterial oxygenation, however, was preserved in overlap compared to COPD. Blunted limb perfusion was related to greater muscle deoxygenation and lactate concentration in overlap (r = 0.78 and r = 0.73, respectively; p < 0.05). ΔBlood flow/ΔO2 uptake was related to time to exercise intolerance only in overlap and heart failure (p < 0.01). In conclusion, COPD and heart failure add to decrease exercising cardiac output and skeletal muscle perfusion to a greater extent than that expected by heart failure alone. Treatment strategies that increase muscle O2 delivery and/or decrease O2 demand may be particularly helpful to improve exercise tolerance in COPD patients presenting heart failure as co-morbidity.

Exertional oscillatory ventilation in subjects without heart failure reporting chronic dyspnoea.

Oscillatory ventilation detected on incremental cardiopulmonary exercise testing might be found in subjects without heart failure reporting exertional dyspnoea despite the best available therapy for their underlying cardiopulmonary disease https://bit.ly/3Tyl7bE.

Exercise intolerance in post-coronavirus disease 2019 survivors after hospitalisation.

Rationale: Post-coronavirus disease 2019 (COVID-19) survivors frequently have dyspnoea that can lead to exercise intolerance and lower quality of life. Despite recent advances, the pathophysiological mechanisms of exercise intolerance in the post-COVID-19 patients remain incompletely characterised. The objectives of the present study were to clarify the mechanisms of exercise intolerance in post-COVID-19 survivors after hospitalisation. Methods: This prospective study evaluated consecutive patients previously hospitalised due to moderate-to-severe/critical COVID-19. Within mean±sd 90±10 days of onset of acute COVID-19 symptoms, patients underwent a comprehensive cardiopulmonary assessment, including cardiopulmonary exercise testing with earlobe arterialised capillary blood gas analysis. Measurements and main results: 87 patients were evaluated; mean±sd peak oxygen consumption was 19.5±5.0 mL·kg-1·min-1, and the tertiles were ≤17.0, 17.1-22.2 and ≥22.3 mL·kg-1·min-1. Hospitalisation severity was similar among the three groups; however, at the follow-up visit, patients with peak oxygen consumption ≤17.0 mL·kg-1·min-1 reported a greater sensation of dyspnoea, along with indices of impaired pulmonary function, and abnormal ventilatory, gas-exchange and metabolic responses during exercise compared to patients with peak oxygen consumption >17 mL·kg-1·min-1. By multivariate logistic regression analysis (receiver operating characteristic curve analysis) adjusted for age, sex and prior pulmonary embolism, a peak dead space fraction of tidal volume ≥29 and a resting forced vital capacity ≤80% predicted were independent predictors of reduced peak oxygen consumption. Conclusions: Exercise intolerance in the post-COVID-19 survivors was related to a high dead space fraction of tidal volume at peak exercise and a decreased resting forced vital capacity, suggesting that both pulmonary microcirculation injury and ventilatory impairment could influence aerobic capacity in this patient population.

Sildenafil improves microvascular O2 delivery-to-utilization matching and accelerates exercise O2 uptake kinetics in chronic heart failure.

Nitric oxide (NO) can temporally and spatially match microvascular oxygen (O(2)) delivery (Qo(2mv)) to O(2) uptake (Vo(2)) in the skeletal muscle, a crucial adjustment-to-exercise tolerance that is impaired in chronic heart failure (CHF). To investigate the effects of NO bioavailability induced by sildenafil intake on muscle Qo(2mv)-to-O(2) utilization matching and Vo(2) kinetics, 10 males with CHF (ejection fraction = 27 ± 6%) undertook constant work-rate exercise (70-80% peak). Breath-by-breath Vo(2), fractional O(2)extraction in the vastus lateralis {∼deoxygenated hemoglobin + myoglobin ([deoxy-Hb + Mb]) by near-infrared spectroscopy}, and cardiac output (CO) were evaluated after sildenafil (50 mg) or placebo. Sildenafil increased exercise tolerance compared with placebo by ∼20%, an effect that was related to faster on- and off-exercise Vo(2) kinetics (P < 0.05). Active treatment, however, failed to accelerate CO dynamics (P > 0.05). On-exercise [deoxy-Hb + Mb] kinetics were slowed by sildenafil (∼25%), and a subsequent response "overshoot" (n = 8) was significantly lessened or even abolished. In contrast, [deoxy-Hb + Mb] recovery was faster with sildenafil (∼15%). Improvements in muscle oxygenation with sildenafil were related to faster on-exercise Vo(2) kinetics, blunted oscillations in ventilation (n = 9), and greater exercise capacity (P < 0.05). Sildenafil intake enhanced intramuscular Qo(2mv)-to-Vo(2) matching with beneficial effects on Vo(2) kinetics and exercise tolerance in CHF. The lack of effect on CO suggests that improvement in blood flow to and within skeletal muscles underlies these effects.

Effects of bi-level positive airway pressure on ventilatory and perceptual responses to exercise in comorbid heart failure-COPD.

This study tested the hypothesis that, by increasing the volume available for tidal expansion (inspiratory capacity, IC), bi-level positive airway pressure (BiPAP™) would lead to greater beneficial effects on dyspnea and exercise intolerance in comorbid heart failure (HF)-chronic obstructive pulmonary disease (COPD) than HF alone. Ten patients with HF and 9 with HF-COPD (ejection fraction = 30 ± 6% and 35 ± 7%; FEV1 = 83 ± 12% and 65 ± 15% predicted, respectively) performed a discontinuous exercise protocol under sham ventilation or BiPAP™. Time to intolerance increased with BiPAP™ only in HF-COPD (p < 0.05). BiPAP™ led to higher tidal volume and lower duty cycle with longer expiratory time (p < 0.05). Of note, BiPAP™ improved IC (by ∼0.5 l) across exercise intensities only in HF-COPD. These beneficial consequences were associated with lower dyspnea scores at higher levels of ventilation (p < 0.05). By improving the qualitative" (breathing pattern and operational lung volumes) and sensory (dyspnea) features of exertional ventilation, BiPAP™ might allow higher exercise intensities to be sustained for longer during cardiopulmonary rehabilitation in HF-COPD.

Safety and Efficacy of Aerobic Exercise Training Associated to Non-Invasive Ventilation in Patients with Acute Heart Failure.

BACKGROUND: Exercise training (ET) improves functional capacity in chronic heart failure (HF). However, ET effects in acute HF are unknown. OBJECTIVE: To investigate the effects of ET alone or combined with noninvasive ventilation (NIV) compared with standard medical treatment during hospitalization in acute HF patients. METHODS: Twenty-nine patients (systolic HF) were randomized into three groups: control (Control - only standard medical treatment); ET with placebo NIV (ET+Sham) and ET+NIV (NIV with 14 and 8 cmH2O of inspiratory and expiratory pressure, respectively). The 6MWT was performed on day 1 and day 10 of hospitalization and the ET was performed on an unloaded cycle ergometer until patients' tolerance limit (20 min or less) for eight consecutive days. For all analyses, statistical significance was set at 5% (p < 0.05). RESULTS: None of the patients in either exercise groups had adverse events or required exercise interruption. The 6MWT distance was greater in ET+NIV (Δ120 ± 72 m) than in ET+Sham (Δ73 ± 26 m) and Control (Δ45 ± 32 m; p < 0.05). Total exercise time was greater (128 ± 10 vs. 92 ± 8 min; p < 0.05) and dyspnea was lower (3 ± 1 vs. 4 ± 1; p < 0.05) in ET+NIV than ET+Sham. The ET+NIV group had a shorter hospital stay (17 ± 10 days) than ET+Sham (23 ± 8 days) and Control (39 ± 15 days) groups (p < 0.05). Total exercise time in ET+Sham and ET+NIV had significant correlation with length of hospital stay (r = -0.75; p = 0.01). CONCLUSION: Exercise training in acute HF was safe, had no adverse events and, when combined with NIV, improved 6MWT and reduce dyspnea and length of stay.

Current challenges in managing comorbid heart failure and COPD.

INTRODUCTION: Heart failure (HF) with reduced ejection fraction and chronic obstructive pulmonary disease (COPD) frequently coexist, particularly in the elderly. Given their rising prevalence and the contemporary trend to longer life expectancy, overlapping HF-COPD will become a major cause of morbidity and mortality in the next decade. Areas covered: Drawing on current clinical and physiological constructs, the consequences of negative cardiopulmonary interactions on the interpretation of pulmonary function and cardiopulmonary exercise tests in HF-COPD are discussed. Although those interactions may create challenges for the diagnosis and assessment of disease stability, they provide a valuable conceptual framework to rationalize HF-COPD treatment. The impact of COPD or HF on the pharmacological treatment of HF or COPD, respectively, is then comprehensively discussed. Authors finalize by outlining how the non-pharmacological treatment (i.e. rehabilitation and exercise reconditioning) can be tailored to the specific needs of patients with HF-COPD. Expert commentary: Randomized clinical trials testing the efficacy and safety of new medications for HF or COPD should include a sizeable fraction of patients with these coexistent pathologies. Multidisciplinary clinics involving cardiologists and respirologists trained in both diseases (with access to unified cardiorespiratory rehabilitation programs) are paramount to decrease the humanitarian and social burden of HF-COPD.

Hemodynamics and tissue oxygenation effects after increased in positive end-expiratory pressure in coronary artery bypass surgery.

BACKGROUND: Cardiac surgery is widely used in the treatment of cardiovascular diseases. However, several complications can be observed during the postoperative period. Positive end expiratory pressure (PEEP) improves gas exchange, but it might be related to decreased cardiac output and possible impairment of tissue oxygenation. The aim of this study was to investigate the hemodynamic effects and oxygen saturation of central venous blood (ScvO2) after increasing PEEP in hypoxemic patients after coronary artery bypass (CAB) surgery. METHODS: Seventy post-cardiac surgery patients (CAB), 61 ± 7 years, without ventricular dysfunction (left ventricular ejection fraction 57 ± 2%), with hypoxemia (PaO2/FiO2 ratio <200) were enrolled. Heart rate, mean arterial pressure, arterial and venous blood samples were measured at intensive care unit and PEEP was increased to 12 cmH2O for 30 min. RESULTS: As expected, PEEP12 improved arterial oxygenation and PaO2/FiO2 ratio (p < 0.0001). Reduction in ScvO2 was observed between PEEP5 (63 ± 2%) and PEEP12 (57 ± 1%; p = 0.01) with higher values of blood lactate in PEEP12 (p < 0.01). No hemodynamic effects (heart rate, mean arterial pressure, SpO2; p > 0.05) were related. CONCLUSION: Increased PEEP after cardiac surgery decreased ScvO2 and increased blood lactate, even with higher O2 delivery. PEEP did not interfere in hemodynamics status in CAB patients, suggesting that peripheral parameters must be controlled and measured during procedures involving increased PEEP in post-cardiac surgery patients in the intensive care unit.

Physiological and sensory consequences of exercise oscillatory ventilation in heart failure-COPD.

BACKGROUND: Exercise oscillatory ventilation (EOV) is associated with poor ventilatory efficiency and higher operating lung volumes in heart failure. These abnormalities may be particularly deleterious to dyspnea and exercise tolerance in mechanically-limited patients, e.g. those with coexistent COPD. METHODS: Ventilatory, gas exchange and sensory responses to incremental exercise were contrasted in 68 heart failure-COPD patients (12 EOV+). EOV was established by standard criteria. RESULTS: Compared to EOV-, EOV+ had lower exercise capacity, worse ventilatory inefficiency and higher peak dyspnea scores (p<0.05). Peak capillary PCO2 (PcCO2) was higher and end-tidal CO2 (PETCO2) was lower in EOV+. Thus, greater (i.e., more positive) P(c-ET)CO2 and dead space/tidal volume values were found in these patients compared to EOV- (p<0.05). Ventilatory inefficiency was related to increased dead space/tidal volume in EOV+ (r=0.74; p<0.01). Owing to higher operating lung volumes, inspiratory reserve volume (IRV) decreased to a greater extent in EOV+. Tidal volume oscillations consistently ceased when a "critical" IRV was reached (~0.3-0.5L); thereafter, PcCO2 stabilized or increased and dyspnea scores rose sharply. Exercise capacity was closely related to IRV decrements and peak dyspnea in EOV+ (r=-0.78 and 0.84, respectively; p<0.01). CONCLUSIONS: Dyspnea and exercise tolerance are negatively influenced by EOV in heart failure patients presenting with COPD as co-morbidity. Pharmacological and non-pharmacological interventions known to decrease EOV might prove particularly valuable to mitigate symptom burden and exercise intolerance in this specific heart failure group.

Alternatives to Aerobic Exercise Prescription in Patients with Chronic Heart Failure.

BACKGROUND: Exercise is essential for patients with heart failure as it leads to a reduction in morbidity and mortality as well as improved functional capacity and oxygen uptake (v̇O2). However, the need for an experienced physiologist and the cost of the exam may render the cardiopulmonary exercise test (CPET) unfeasible. Thus, the six-minute walk test (6MWT) and step test (ST) may be alternatives for exercise prescription. OBJECTIVE: The aim was to correlate heart rate (HR) during the 6MWT and ST with HR at the anaerobic threshold (HRAT) and peak HR (HRP) obtained on the CPET. METHODS: Eighty-three patients (58 ± 11 years) with heart failure (NYHA class II) were included and all subjects had optimized medication for at least 3 months. Evaluations involved CPET (v̇O2, HRAT, HRP), 6MWT (HR6MWT) and ST (HRST). RESULTS: The participants exhibited severe ventricular dysfunction (ejection fraction: 31 ± 7%) and low peak v̇O2 (15.2 ± 3.1 mL.kg-1.min-1). HRP (113 ± 19 bpm) was higher than HRAT (92 ± 14 bpm; p < 0.05) and HR6MWT (94 ± 13 bpm; p < 0.05). No significant difference was found between HRP and HRST. Moreover, a strong correlation was found between HRAT and HR6MWT (r = 0.81; p < 0.0001), and between HRP and HRST (r = 0.89; p < 0.0001). CONCLUSION: These findings suggest that, in the absence of CPET, exercise prescription can be performed by use of 6MWT and ST, based on HR6MWT and HRST.

Does Exercise Ventilatory Inefficiency Predict Poor Outcome in Heart Failure Patients With COPD?

PURPOSE: To investigate whether the opposite effects of heart failure (HF) and chronic obstructive pulmonary disease (COPD) on exercise ventilatory inefficiency (minute ventilation [(Equation is included in full-text article.)E]-carbon dioxide output [(Equation is included in full-text article.)CO2] relationship) would negatively impact its prognostic relevance. METHODS: After treatment optimization and an incremental cardiopulmonary exercise test, 30 male patients with HF-COPD (forced expiratory volume in 1 second [FEV1] = 57% ± 17% predicted, ejection fraction = 35% ± 6%) were prospectively followed up during 412 ± 261 days for major cardiac events. RESULTS: Fourteen patients (46%) had a negative outcome. Patients who had an event had lower echocardiographically determined right ventricular fractional area change (RVFAC), greater ventilatory inefficiency (higher (Equation is included in full-text article.)E/(Equation is included in full-text article.)CO2 nadir), and lower end-tidal CO2 (PETCO2) (all P < .05). Multivariate Cox models revealed that (Equation is included in full-text article.)E/(Equation is included in full-text article.)CO2 nadir >36, ΔPETCO2(PEAK-REST)≥2 mm Hg, and PETCO2PEAK≤33 mm Hg added prognostic value to RVFAC≤45%. Kaplan-Meyer analyses showed that although 18% of patients with RVFAC>45% had a major cardiac event after 1 year, no patient with RVFAC>45% and (Equation is included in full-text article.)E/(Equation is included in full-text article.)CO2 nadir ≤36 (or PETCO2PEAK>33 mm Hg) had a negative event. Conversely, although 69% of patients with RVFAC≤45% had a major cardiac event after 1 year, all patients with RVFAC≤45% and ΔPETCO2(PEAK-REST)≥2 mm Hg had a negative event. CONCLUSION: Ventilatory inefficiency remains a powerful prognostic marker in HF despite the presence of mechanical ventilatory constraints induced by COPD. If these preliminary findings are confirmed in larger studies, optimal thresholds for outcome prediction are likely greater than those traditionally recommended for HF patients without COPD.

Safety and Efficacy of Aerobic Exercise Training Associated to Non-Invasive Ventilation in Patients with Acute Heart Failure / Segurança e Eficácia do Treinamento Aeróbio Combinado à Ventilação Não-Invasiva em Pacientes com Insuficiência Cardíaca Aguda

Abstract Background: Exercise training (ET) improves functional capacity in chronic heart failure (HF). However, ET effects in acute HF are unknown. Objective: To investigate the effects of ET alone or combined with noninvasive ventilation (NIV) compared with standard medical treatment during hospitalization in acute HF patients. Methods: Twenty-nine patients (systolic HF) were randomized into three groups: control (Control - only standard medical treatment); ET with placebo NIV (ET+Sham) and ET+NIV (NIV with 14 and 8 cmH2O of inspiratory and expiratory pressure, respectively). The 6MWT was performed on day 1 and day 10 of hospitalization and the ET was performed on an unloaded cycle ergometer until patients' tolerance limit (20 min or less) for eight consecutive days. For all analyses, statistical significance was set at 5% (p < 0.05). Results: None of the patients in either exercise groups had adverse events or required exercise interruption. The 6MWT distance was greater in ET+NIV (Δ120 ± 72 m) than in ET+Sham (Δ73 ± 26 m) and Control (Δ45 ± 32 m; p < 0.05). Total exercise time was greater (128 ± 10 vs. 92 ± 8 min; p < 0.05) and dyspnea was lower (3 ± 1 vs. 4 ± 1; p < 0.05) in ET+NIV than ET+Sham. The ET+NIV group had a shorter hospital stay (17 ± 10 days) than ET+Sham (23 ± 8 days) and Control (39 ± 15 days) groups (p < 0.05). Total exercise time in ET+Sham and ET+NIV had significant correlation with length of hospital stay (r = -0.75; p = 0.01). Conclusion: Exercise training in acute HF was safe, had no adverse events and, when combined with NIV, improved 6MWT and reduce dyspnea and length of stay.

Resumo Fundamento: O exercício físico melhora a capacidade funcional em pacientes com insuficiência cardíaca (IC) crônica. Entretanto, os efeitos do exercício na IC aguda são desconhecidos. Objetivo: Investigar os efeitos do exercício físico isolado ou associado à ventilação não-invasiva (VNI) em comparação ao tratamento convencional em pacientes com IC durante internação. Métodos: Vinte e nove pacientes (IC sistólica) foram randomizados em três grupos: Controle (tratamento clínico convencional); exercício com ventilação placebo (EX+Sham) e EX+VNI (VNI com 14 e 8 cmH2O de pressão inspiratória e expiratória, respectivamente).O TC6M foi realizado no primeiro e no décimo dia de internação e o exercício realizado em cicloergômetro até o limite de tolerância (20 minutos ou menos) por oito dias consecutivos. Para todas as análises, foi considerado p < 0,05 estatisticamente significante. Resultados: Nenhum paciente dos grupos EX+Sham e EX+VNI apresentou complicações ou necessitou interromper o exercício. O grupo EX+VNI apresentou melhor desempenho no TC6M (Δ120 ± 72 m) que os grupos EX+Sham (Δ73 ± 26 m) e Controle (Δ45 ± 32 m; p < 0,05). O tempo total de exercício foi maior (128 ± 10 vs. 92 ± 8 min; p < 0,05) e a dispneia menor (3 ± 1 vs. 4 ± 1; p < 0,05) no EX+VNI em relação ao EX+Sham. O grupo EX+VNI apresentou menor tempo de internação (17 ± 10 dias) comparado ao EX+Sham (23 ± 8 dias) e Controle (39 ± 15 dias; p < 0,05). O tempo total de exercício nos grupos EX+Sham e EX+VNI correlacionou-se com o tempo de internação hospitalar (r = -0,75; p = 0,01). Conclusão: O exercício físico foi seguro em pacientes com IC aguda, não houve complicações hospitalares e, quando associada à VNI, melhorou o desempenho no TC6M, dispneia e o tempo de internação.

Hemodynamics and tissue oxygenation effects after increased in positive end expiratory pressure in coronary artery bypass surgery

BACKGROUND: Cardiac surgery is widely used in the treatment of cardiovascular diseases. However, several complications can be observed during the postoperative period. Positive end expiratory pressure (PEEP) improves gas exchange, but it might be related to decreased cardiac output and possible impairment of tissue oxygenation. The aim of this study was to investigate the hemodynamic effects and oxygen saturation of central venous blood (ScvO2) after increasing PEEP in hypoxemic patients after coronary artery bypass (CAB) surgery. METHODS: Seventy post-cardiac surgery patients (CAB), 61 ± 7 years, without ventricular dysfunction (left ventricular ejection fraction 57 ± 2%), with hypoxemia (PaO2/FiO2 ratio <200) were enrolled. Heart rate, mean arterial pressure, arterial and venous blood samples were measured at intensive care unit and PEEP was increased to 12 cmH2O for 30min. RESULTS: As expected, PEEP12 improved arterial oxygenation and PaO2/FiO2 ratio (p < 0.0001). Reduction in ScvO2 was observed between PEEP5 (63 ± 2%) and PEEP12 (57 ± 1%; p = 0.01) with higher values of blood lactate in PEEP12 (p < 0.01). No hemodynamic effects (heart rate, mean arterial pressure, SpO2; p > 0.05) were related. CONCLUSION: Increased PEEP after cardiac surgery decreased ScvO2 and increased blood lactate, even with higher O2 delivery. PEEP did not interfere in hemodynamics status in CAB patients, suggesting that peripheral parameters must be controlled and measured during procedures involving increased PEEP in post-cardiac surgery patients in the intensive care unit.

Alternatives to Aerobic Exercise Prescription in Patients with Chronic Heart Failure / Alternativas para Prescrição de Exercício Aeróbio a Pacientes com Insuficiência Cardíaca

Background: Exercise is essential for patients with heart failure as it leads to a reduction in morbidity and mortality as well as improved functional capacity and oxygen uptake (v̇O2). However, the need for an experienced physiologist and the cost of the exam may render the cardiopulmonary exercise test (CPET) unfeasible. Thus, the six-minute walk test (6MWT) and step test (ST) may be alternatives for exercise prescription. Objective: The aim was to correlate heart rate (HR) during the 6MWT and ST with HR at the anaerobic threshold (HRAT) and peak HR (HRP) obtained on the CPET. Methods: Eighty-three patients (58 ± 11 years) with heart failure (NYHA class II) were included and all subjects had optimized medication for at least 3 months. Evaluations involved CPET (v̇O2, HRAT, HRP), 6MWT (HR6MWT) and ST (HRST). Results: The participants exhibited severe ventricular dysfunction (ejection fraction: 31 ± 7%) and low peak v̇O2 (15.2 ± 3.1 mL.kg-1.min-1). HRP (113 ± 19 bpm) was higher than HRAT (92 ± 14 bpm; p < 0.05) and HR6MWT (94 ± 13 bpm; p < 0.05). No significant difference was found between HRP and HRST. Moreover, a strong correlation was found between HRAT and HR6MWT (r = 0.81; p < 0.0001), and between HRP and HRST (r = 0.89; p < 0.0001). Conclusion: These findings suggest that, in the absence of CPET, exercise prescription can be performed by use of 6MWT and ST, based on HR6MWT and HRST.

Fundamento: O exercício físico é fundamental para pacientes com insuficiência cardíaca, pois reduz a morbimortalidade e melhora a capacidade funcional e o consumo de oxigênio (v̇O2). Entretanto, a realização do teste de exercício cardiopulmonar (TECP) pode se tornar inviável, devido à necessidade de médico capacitado e ao alto custo deste exame. Assim, o teste de caminhada de 6 minutos (TC6M) e o teste do degrau (TD) emergem como alternativas para a prescrição de exercício. Objetivo: Correlacionar a frequência cardíaca (FC) durante o TC6M e o TD com a FC no limiar aeróbio (FCLA) e a FC no pico do exercício (FCP), obtidas no TECP. Métodos: Foram incluídos 83 pacientes (58 ± 11 anos) com insuficiência cardíaca (NYHA classe II), com medicação otimizada por pelo menos 3 meses. Foram realizados TECP (v̇O2, FCLA e FCP), TC6M (FCTC6M) e TD (FCTD). Resultados: Os pacientes apresentavam disfunção ventricular grave (fração de ejeção: 31 ± 7%) e baixo v̇O2 pico (15,2 ± 3,1 ml.kg-1.min-1). A FCP (113 ± 19 bpm) foi maior que a FCLA (92 ± 14 bpm; p < 0,05) e a FCTC6M (94 ± 13 bpm; p < 0,05). Não houve diferença entre FCP e FCTD. Além disso, observou-se forte correlação entre a FCLA e a FCTC6M (r = 0,81; p < 0,0001) e entre a FCP e a FCTD (r = 0,89; p < 0,0001). Conclusão: Os resultados obtidos sugerem ser viável a prescrição de exercício através do TC6M e do TD, com base na FCTC6M e na FCTD, na ausência do TECP.