Orlando Díaz

Sex differences in mortality in patients with COPD

Little is known about survival and clinical prognostic factors in females with chronic obstructive pulmonary disease (COPD). The aim of the present study was to determine the survival difference between males and females with COPD and to compare the value of the different prognostic factors for the disease. In total, 265 females and 272 males with COPD matched at baseline by BODE (body mass index, airflow obstruction, dyspnoea, exercise capacity) and American Thoracic Society/European Respiratory Society/Global Initiative of Chronic Obstructive Lung Disease criteria were prospectively followed. Demographics, lung function, St George’s Respiratory Questionnaire, BODE index, the components of the BODE index and comorbidity were determined. Survival was documented and sex differences were determined using Kaplan–Meier analysis. The strength of the association of the studied variables with mortality was determined using multivariate and receiver operating curves analysis. All-cause (40 versus 18%) and respiratory mortality (24 versus 10%) were higher in males than females. Multivariate analysis identified the BODE index in females and the BODE index and Charlson comorbidity score in males as the best predictors of mortality. The area under the curve of the BODE index was a better predictor of mortality than the forced expiratory volume in one second for both sexes. At similar chronic obstructive pulmonary disease severity by BODE index and forced expiratory volume in one second, females have significantly better survival than males. For both sexes the BODE index is a better predictor of survival than the forced expiratory volume in one second.

Effects of noninvasive ventilation on lung hyperinflation in stable hypercapnic COPD

Two previous uncontrolled studies have suggested that noninvasive mechanical ventilation (NIMV) in patients with hypercapnic chronic obstructive pulmonary disease (COPD) improves arterial blood gas tensions by decreasing lung hyperinflation with the consequent reduction in inspiratory loads and changes in ventilatory pattern. The aim of this randomised placebo-controlled study was to determine whether these mechanisms play a pivotal role in the effects of NIMV on arterial blood gases. Thirty-six stable hypercapnic COPD patients were randomly allocated to NIMV or sham NIMV. A 2-week run-in period was followed by a 3-week study period, during which ventilation was applied 3 h·day−1, 5 days a week. Arterial blood gases, spirometry, lung volumes, and respiratory mechanics were measured before and after application of NIMV. Patients submitted to NIMV showed changes (mean (95% confidence interval)) in daytime arterial carbon dioxide tension (Pa,CO2) and arterial oxygen tension of −1.12 (−1.52–−0.73) kPa (−8.4 (−11.4–−5.5) mmHg) and 1.14 (0.70–1.50) kPa (8.6 (5.3–11.9) mmHg), respectively. Total lung capacity, functional residual capacity (FRC) and residual volume were found to be reduced by 10 (7–13), 25 (18–31), and 36 (27–45)% of their predicted value, respectively, whereas forced expiratory volume in one second and forced vital capacity increased by 4 (1.5–6.9) and 9 (5–13)% pred, respectively. Tidal volume (VT) increased by 181 (110–252) mL. All of the above changes were significant compared with sham NIMV. Changes in Pa,CO2 were significantly related to changes in dynamic intrinsic positive end-expiratory pressure, inspiratory lung impedance, VT and FRC. It was concluded that the beneficial effects of noninvasive mechanical ventilation could be explained by a reduction in lung hyperinflation and inspiratory loads.

Pedometers to enhance physical activity in COPD: a randomised controlled trial.

Physical inactivity is a cardinal feature of chronic obstructive pulmonary disease (COPD), and is associated with increased morbidity and mortality. Pedometers, which have been used in healthy populations, might also increase physical activity in patients with COPD. COPD patients taking part in a 3-month individualised programme to promote an increase in their daily physical activity were randomised to either a standard programme of physical activity encouragement alone, or a pedometer-based programme. Assessments were performed by investigators blinded to treatment allocation. Change in average 1-week daily step count, 6-min walking distance (6MWD), modified Medical Research Council scale, St George’s respiratory questionnaire (SGRQ) and COPD assessment test (CAT) were compared between groups. 102 patients were recruited, of whom 97 completed the programme (pedometer group: n=50; control group: n=47); 60.8% were male with a mean±sd age of 68.7±8.5 years, and forced expiratory volume in 1 s (FEV1) 66.1±19.4% and FEV1/forced vital capacity 55.2±9.5%. Both groups had comparable characteristics at baseline. The pedometer group had significantly greater improvements in: physical activity 3080±3254 steps·day−1 versus 138.3±1950 steps·day−1 (p<0.001); SGRQ −8.8±12.2 versus −3.8±10.9 (p=0.01); CAT score −3.5±5.5 versus −0.6±6.6 (p=0.001); and 6MWD 12.4±34.6 versus −0.7±24.4 m (p=0.02) than patients receiving activity encouragement only. A simple physical activity enhancement programme using pedometers can effectively improve physical activity level and quality of life in COPD patients. Pedometer-based programme produced clinically important improvements in physical activity and health status in COPD http://ow.ly/AmcCO

Breathing pattern and gas exchange at peak exercise in COPD patients with and without tidal flow limitation at rest

Expiratory flow limitation (FL) at rest is frequently present in chronic obstructive pulmonary disease (COPD) patients. It promotes dynamic hyperinflation with a consequent decrease in inspiratory capacity (IC). Since in COPD resting IC is strongly correlated with exercise tolerance, this study hypothesized that this is due to limitation of the maximal tidal volume (VT,max) during exercise by the reduced IC. The present study investigated the role of tidal FL at rest on: 1) the relationship of resting IC to VT,max; and 2) on gas exchange during peak exercise in COPD patients. Fifty-two stable COPD patients were studied at rest, using the negative expiratory pressure technique to assess the presence of FL, and during incremental symptom-limited cycling exercise to evaluate exercise performance. At rest, FL was present in 29 patients. In the 52 patients, a close relationship of VT,max to IC was found using non-normalized values (r=0.77; p < 0.0001), and stepwise regression analysis selected IC as the only significant predictor of VT,max. Subgroup analysis showed that this was also the case for patients both with and without FL (r=0.70 and 0.76, respectively). In addition, in FL patients there was an increase (p < 0.002) in arterial carbon dioxide partial pressure at peak exercise, mainly due to a relatively low VT,max and consequent increase in the physiological dead space (VD)/VT ratio. The arterial oxygen partial pressure also decreased at peak exercise in the FL patients (p < 0.05). In conclusion, in chronic obstructive pulmonary disease patients the maximal tidal volume, and hence maximal oxygen consumption, are closely related to the reduced inspiratory capacity. The flow limited patients also exhibit a significant increase in arterial carbon dioxide partial pressure and a decrease in arterial oxygen partial pressure during peak exercise.

Use of methylene blue in patients with refractory septic shock: Impact on hemodynamics and gas exchange

PURPOSE The purpose of this study was to assess the acute effects of methylene blue, an inhibitor of nitric oxide synthesis, on hemodynamics and gas exchange in patients with refractory septic shock in a prospective clinical trial at medical and surgical intensive care units in a tertiary university hospital. PATIENTS AND METHODS Prospective, sequential study of 10 consecutive patients admitted with severe septic shock of diverse causes and unable to achieve an adequate arterial pressure despite the use of at least two vasoactive drugs. Six of them also developed acute lung injury. All received 1 mg/kg intravenous bolus of methylene blue. Hemodynamic and respiratory parameters were measured at baseline and at 30, 60, 120, and 180 minutes after the bolus injection. RESULTS Systolic, diastolic, mean arterial blood pressure, and systemic vascular resistance increased significantly in all patients, whereas no significant changes were observed in cardiac output, oxygen consumption, or oxygen extraction ratio. Gas exchange remained unaffected in patients with acute lung injury. CONCLUSIONS Methylene blue had an acute vasopressor effect in patients with refractory septic shock, and it was not deleterious on respiratory function.

Physiological and clinical effects of diurnal noninvasive ventilation in hypercapnic COPD

To assess the clinical impact of noninvasive mechanical ventilation (NIMV) on stable hypercapnic chronic obstructive pulmonary disease, changes in exercise capacity, dyspnoea and simple physiological parameters were evaluated. The time course of these effects during treatment and recovery was also assessed. Patients were randomly allocated to NIMV (n = 27) or sham-NIMV (n = 15), applied 3 h·day−1, 5 days a week, for 3 weeks. A 6-min walking distance (6MWD), arterial blood gases, spirometry, pattern of breathing, mouth occlusion pressure (P0.1), and respiratory system impedance (P0.1/tidal volume (VT)/inspiratory time (tI)) were measured weekly during treatment and 2 weekly during follow-up. Transition dyspnoea index (TDI) was also measured. During NIMV, carbon dioxide arterial tension decreased progressively, concomitantly with a slow deep pattern of breathing, a proportional increase in the forced expiratory volume in one second (FEV1), the forced vital capacity and significant reductions of P0.1 and P0.1/VT/tI. The 6MWD improved by a mean of 76 m after NIMV, and by 73 m and 61 m 1 and 2 weeks, respectively, after treatment. Dyspnoea improved with a mean TDI of three points. Changes in 6MWD were highly related to TDI and to a lesser extent to changes in FEV1 (r = 0.60). The current authors conclude that noninvasive mechanical ventilation has significant and sustained clinical impact in stable hypercapnic chronic obstructive pulmonary disease.

Prognostic assessment in COPD: health related quality of life and the BODE index.

RATIONALE COPD is a debilitating disease with increasing mortality worldwide. The BODE index evaluates disease severity and the St Georges Respiratory Questionnaire (SGRQ) measures health status. OBJECTIVE To identify the relationship between BODE index and the SGRQ and to test the predictive value of both tools against survival. METHODS Open cohort study of 1398 COPD patients (85% male) followed for up to 10 years. MEASUREMENTS AND MAIN RESULTS At the time of the inclusion, clinical data, forced spirometry and 6 min walking distance were determined and BODE index and SGRQ were calculated. Vital status and cause of death were documented at the end of follow-up. RESULTS The cohorts mean of FEV1% predicted was 46 ± 18%, BODE index was 3.6 ± 2.5, and SGRQ% total score was 49 ± 20. The SGRQ scores increased progressively as severity of COPD increased by BODE quartiles. The correlation between SGRQ and BODE index was good (r = 0.58, p < 0.0001). Both tests correlated with COPD survival (BODE = -0.4 vs. SGRQ = -0.20, p < 0.0001). The area under the curve (AUC) for the BODE index was 0.77 vs. 0.66 for the SGRQ % total score (p < 0.001). CONCLUSIONS Health status as measured by SGRQ worsens with disease severity evaluated by the BODE index. Both tools predict mortality and provide complimentary information in the evaluation of patients with COPD.

Ventilación mecánica no invasiva en pacientes con enfermedades neuromusculares y en pacientes con alteraciones de la caja torácica

from negative pressure ventilators was widely used to treat respiratory insufficiency in patients with poliomyelitis between 1930 and 1960, leading to dramatic decreases in mortality. The publication of various noncontrolled trials describing cases successfully treated with NIV 4-9 has meant that, for ethical reasons, hardly any controlled trials have been designed. Available reports indicate that NIV is able to reverse alveolar hypoventilation, improve quality of life and prolong survival in neurological patients, as well as provide other benefits. Nevertheless, it may be that such findings overestimate the benefits of NIV , given that negative results are seldom reported. The only controlled studies of NIV are those of Vianello et al 10 and Shonhofer et al 11 . The former observed clinical and functional benefits in patients with Duchenne muscular dystrophy and the latter reported positive results in patients with chest restriction. In this review, we discuss the underlying pathophysiology of NIV use in patients with neurological diseases, the general mechanisms of action of the technique and its indications and complications. We also analyze the mechanisms involved and results obtained with NIV in two neuromuscular diseases.

Six-Minute Walk Test and Maximum Exercise Test in Cycloergometer in Chronic Obstructive Pulmonary Disease. Are the Physiological Demands Equivalent?

a b s t r a c t Background and objectives: The physiological load imposed by the six minute walk test (SMWT) in chronic obstructive pulmonary disease (COPD) patients come from small studies where the influence of disease severity has not been assessed. The aim of the present study was to compare the SMWT with an incremental cardiopulmonary exercise test (CPET) in patients classified by disease severity according to FEV1 (cutoff 50% predicted). Patients and methods: Eighty-one COPD patients (53 with FEV1 ≥50%) performed both tests on two consecutive days. Oxygen consumption (V. O2), carbon dioxide production (V. O2), minute ventilation (V. E), heart rate (HR) and pulse oximetry (SpO2) were measured during SMWT and CPET using portable equipment. Dyspnea and leg fatigue were measured with the Borg scale. Results: In both groups, walking speed was constant during the SMWT and V. O2 showed a plateau after the 3rd minute. When comparing SMWT (6th min) and peak CPET, patients with FEV1 ≥50% showed a greater V. O2, but lower values of V. O2,VE, HR, dyspnea, leg fatigue, and SpO2 during walking. In contrast, in those with FEV1 <50% predicted values were similar. Distance walked during the SMWT strongly correlated with V. O2 at peak CPET (r=0.78; P=0.0001). Conclusion: The SMWT is a constant load exercise in COPD patients, regardless of disease severity. It imposes high metabolic, ventilatory and cardiovascular requirements, which were closer to those of CPET in severe COPD. These findings may explain the close correlation between distance walked and peak CPET V. O2.

Prueba de marcha de 6 min y ejercicio máximo en cicloergómetro en la enfermedad pulmonar obstructiva crónica, ¿son sus demandas fisiológicas equivalentes?

BACKGROUND AND OBJECTIVES The physiological load imposed by the six minute walk test (SMWT) in chronic obstructive pulmonary disease (COPD) patients come from small studies where the influence of disease severity has not been assessed. The aim of the present study was to compare the SMWT with an incremental cardiopulmonary exercise test (CPET) in patients classified by disease severity according to FEV(1) (cutoff 50% predicted). PATIENTS AND METHODS Eighty-one COPD patients (53 with FEV(1) > or =50%) performed both tests on two consecutive days. Oxygen consumption (VO(2)), carbon dioxide production (VCO(2)), minute ventilation (V(E)), heart rate (HR) and pulse oximetry (SpO(2)) were measured during SMWT and CPET using portable equipment. Dyspnea and leg fatigue were measured with the Borg scale. RESULTS In both groups, walking speed was constant during the SMWT and VO(2) showed a plateau after the 3rd minute. When comparing SMWT (6th min) and peak CPET, patients with FEV(1) > or =50% showed a greater VO(2), but lower values of VCO(2),V(E), HR, dyspnea, leg fatigue, and SpO(2) during walking. In contrast, in those with FEV(1) <50% predicted values were similar. Distance walked during the SMWT strongly correlated with VO(2) at peak CPET (r=0.78; P=0.0001). CONCLUSION The SMWT is a constant load exercise in COPD patients, regardless of disease severity. It imposes high metabolic, ventilatory and cardiovascular requirements, which were closer to those of CPET in severe COPD. These findings may explain the close correlation between distance walked and peak CPET VO(2).