The 6-min walk distance in healthy subjects: reference standards from seven countries.

The 6-min walk distance (6MWD) predicted values have been derived from small cohorts mostly from single countries. The aim of the present study was to investigate differences between countries and identify new reference values to improve 6MWD interpretation. We studied 444 subjects (238 males) from seven countries (10 centres) ranging 40-80 yrs of age. We measured 6MWD, height, weight, spirometry, heart rate (HR), maximum HR (HR(max)) during the 6-min walk test/the predicted maximum HR (HR(max) % pred), Borg dyspnoea score and oxygen saturation. The mean ± sd 6MWD was 571 ± 90 m (range 380-782 m). Males walked 30 m more than females (p < 0.001). A multiple regression model for the 6MWD included age, sex, height, weight and HR(max) % pred (adjusted r² = 0.38; p < 0.001), but there was variability across centres (adjusted r² = 0.09-0.73) and its routine use is not recommended. Age had a great impact in 6MWD independent of the centres, declining significantly in the older population (p < 0.001). Age-specific reference standards of 6MWD were constructed for male and female adults. In healthy subjects, there were geographic variations in 6MWD and caution must be taken when using existing predictive equations. The present study provides new 6MWD standard curves that could be useful in the care of adult patients with chronic diseases.

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 hyperinflation on the oxygen pulse as a marker of cardiac performance in COPD.

A decreased inspiratory capacity (IC)/total lung capacity (TLC) ratio is associated with dynamic hyperinflation and decreased exercise capacity. The present authors hypothesised that static (low IC/TLC) and dynamic hyperinflation impair cardiac function as assessed by oxygen pulse at rest and during cardiopulmonary exercise testing (CPET). Lung function, body mass index, hand grip strength and CPET parameters were measured (oxygen uptake (mL x kg(-1) x min(-1)) and oxygen pulse (mL x beat(-1))) in 87 chronic obstructive pulmonary disease (COPD) patients (American Thoracic Society/European Respiratory Society/Global Initiative for Chronic Obstructive Lung Disease stage 3-4) and 46 controls. The patients were divided into those with IC/TLC > 25% or < or = 25%. The IC/TLC ratio at rest and at peak exercise was associated significantly with oxygen pulse. Patients with IC/TLC < or = 25% (n = 45) had significantly lower exercise capacity, peak oxygen pulse, peak minus baseline oxygen pulse, peak IC, peak IC/TLC ratio and % change from baseline to peak IC/TLC ratio compared with patients with IC/TLC > 25% and controls. During CPET, the oxygen pulse was lower at iso-work in patients with IC/TLC < or = 25% than in those with IC/TLC > 25%. Resting hyperinflation (inspiratory capacity/total lung capacity) is associated with lower oxygen pulse, peak exercise inspiratory capacity/total lung capacity and exercise capacity in patients with severe chronic obstructive pulmonary disease. The present results support an interaction between hyperinflation and decreased cardiac function that may contribute to exercise limitation in these patients.

The modified BODE index: validation with mortality in COPD.

Peak oxygen uptake (V'(O(2))) remains the gold standard measurement of exercise capacity and has been associated with survival. A modified BODE (body mass index, airflow obstruction, dyspnoea, exercise capacity) index replacing the 6-min walk distance (6MWD) with V'(O(2)) as % predicted (mBODE%) has been developed and found to have excellent correlation with the conventional BODE index. The objectives of the present study were to compare the ability of the conventional BODE and the mBODE% to predict mortality in 444 patients with chronic obstructive pulmonary disease (COPD) followed for a mean+/-SD period of 71+/-34 months. Anthropometrics, spirometry, lung volumes, comorbidity, cardiopulmonary cyclo-ergometry test and 6MWD were determined at entry. The mean BODE indices for the cohort were: BODE 4.1+/-2 and mBODE% 5.5+/-2. Both indices were significantly correlated with mortality. Logistic regression analysis with COPD survival as the dependent variable identified the BODE index, Charlson's and exercise capacity (in W) as variables associated with this outcome. In conclusion, the conventional BODE index, which uses the 6-min walk distance, predicts mortality in chronic obstructive pulmonary disease as well as the modified index using peak oxygen uptake. The results support the use of the simpler index, which includes the 6-min walk distance in the comprehensive evaluation of patients with chronic obstructive pulmonary disease.

Validation and comparison of reference equations for the 6-min walk distance test.

Exercise impairment as measured by the 6-min walk distance (6MWD) test afflicts many patients with chronic obstructive pulmonary disease (COPD) and is known to predict mortality. Reference equations for the 6MWD in adults have been published but not yet validated. The present authors prospectively followed 1,379 COPD patients for 55+/-30 months and tested the predictive value of the baseline 6MWD in metres, the 6MWD work (kg.m(-1)) and as a percentage of predicted values the 6MWD in meters according to two reference equations. All-cause mortality was the validating outcome. The best threshold values were identified for each of the tests using receiver operating characteristic (ROC) curves. The threshold values obtained were: 350 m for the 6MWD, 25,000 kg.m(-1) for the 6MWD work, and 67 and 54% predicted for the two reference equations. All modalities of the testing were similar at predicting COPD mortality and correlated well with the 6MWD test. In conclusion, all modalities of testing predict mortality in chronic obstructive pulmonary disease equally well. In the 6-min walk distance test, a value <350 m is associated with increased mortality and should be regarded as abnormal.

C-reactive protein in patients with COPD, control smokers and non-smokers.

BACKGROUND: Patients with chronic obstructive pulmonary disease (COPD) have raised serum levels of C reactive protein (CRP). This may be related directly to COPD and its associated systemic inflammation or secondary to other factors such as concomitant ischaemic heart disease (IHD) or smoking status. The aim of this study was to evaluate IHD and smoking as potential causes of raised CRP levels in COPD and to test the association between inhaled corticosteroid (ICS) use and serum CRP levels. METHODS: Cross sectional analyses comparing cohorts of 88 patients with COPD, 33 smokers (S), and 38 non-smoker (NS) controls were performed. Clinical assessments included a complete medical history, pulmonary function, 6 minute walk test (6MWT), cardiopulmonary exercise test, and high sensitivity serum CRP measurements. RESULTS: Serum CRP levels were significantly higher in patients with COPD (5.03 (1.51) mg/l) than in controls (adjusted odds ratio 9.51; 95% confidence interval 2.97 to 30.45) but were similar in the two control groups (S: 2.02 (1.04) mg/l; NS: 2.24 (1.04) mg/l). There was no clinical or exercise evidence of unstable IHD in any of the subjects. CRP levels were lower in COPD patients treated with ICS than in those not treated (3.7 (3.0) mg/l v 6.3 (3.6) mg/l); this association was confirmed in an adjusted regression model (p<0.05). CONCLUSION: CRP levels are raised in COPD patients without clinically relevant IHD and independent of cigarette smoking, and reduced in patients with COPD using ICS. CRP may be a systemic marker of the inflammatory process that occurs in patients with COPD.

The 6-min walk distance: change over time and value as a predictor of survival in severe COPD.

The 6-min walk distance (6MWD) is used to evaluate the functional capacity of patients with chronic obstructive pulmonary disease (COPD). The change in 6MWD over time and its correlation with changes in spirometry and survival are unclear. Patients (n=198) with severe COPD and 41 age-matched controls were followed for 2 yrs, and anthropometrics, spirometry, 6MWD and comorbidities were measured. The 6MWD decreased in the COPD group from 238 +/- 107 m to 218 +/- 112 m (-26 +/- 37 m x yr(-1)), and increased in the control group from 532 +/- 82 m to 549 +/- 86 m (12 +/- 25 m x yr(-1)). In both groups, there was a poor correlation with changes in forced expiratory volume in one second (FEV1). Nonsurvivors in the COPD group (42%) had a more pronounced change in the 6MWD (-40 versus -22 m x yr(-1)) but a similar change in FEV1 (118 versus 102 mL x yr(-1)). The 6MWD independently predicted survival, after accounting for age, body mass index, FEV1 and comorbidities. In severe chronic obstructive pulmonary disease, the 6-min walk distance predicts mortality better than other traditional markers of disease severity. Its measurement is useful in the comprehensive evaluation of patients with severe disease.

Symptom-limited stair climbing as a predictor of postoperative cardiopulmonary complications after high-risk surgery.

STUDY OBJECTIVE: Thoracotomy, sternotomy, and upper abdominal laparotomy are associated with high rate of postoperative cardiopulmonary complications (POCs). We hypothesized that symptom-limited stair climbing predicts POCs after high-risk surgery. DESIGN: A prospective evaluation of 83 patients undergoing thoracotomy, sternotomy, and upper abdominal laparotomy surgery. METHODS: The 52 men and 31 women completed symptom-limited stair climbing. A separate investigator, blinded to the number of flights of stairs climbed, assessed 30-day actual outcomes for POCs, including pneumonia, atelectasis, mechanical ventilation for > 48 h, reintubation, myocardial infarction, congestive heart failure, arrhythmia, pulmonary embolus, and death within 30 days of surgery. The operations performed included 31 lobectomies, 6 wedge resections, 3 pneumonectomies, 3 substernal thymectomies, 1 substernal thyroidectomy, 23 colectomies, 3 laparotomies, 7 abdominal aortic aneurysm repairs, 5 esophagogastrectomies, and 1 nephrectomy. RESULTS: POCs occurred in 21 of 83 patients (25%) overall, in 9 of 44 patients undergoing thoracotomy/sternotomy (20%), and in 12 of 39 patients undergoing upper abdominal laparotomy (31%). Of those unable to climb one flight of stairs, 89% developed a POC. No patient able to climb the maximum of seven flights of stairs had a POC. The inability to climb two flights of stairs was associated with a positive predictive value of 82% for the development of a POC. The number of days in the hospital postoperatively decreased with a patient's increased ability to climb stairs. CONCLUSIONS: Symptom-limited stair climbing offers a simple, inexpensive means to predict POCs after high-risk surgery.

Effect of blood pH on pulmonary artery pressure, left atrial pressure and fluid filtration rate in isolated rabbit lung.

To determine the effects of pH changes on Pulmonary Artery Pressure (PAP), 18 isolated rabbit lung preparations, perfused with autologous blood mixture and constant PaCO2 have been studied. Each preparation was studied under 3 conditions: Baseline: 30 minutes equilibration period. Acidosis: pH was decreased by 0.2 N HCl infusion, the ventilatory rate was changed and different CO2 mixtures were used to maintain the PCO2 within the initial parameters. Compensated Acidosis (CA): pH was returned to normal values by 0.7 N NaHCO3 infusion maintaining PCO2 in its initial values. The decrease in pH (acidosis) from 7.36 +/- 0.05 to 7.18 +/- 0.06 at constant PCO2, generated a significant increase in PAP (13.6 +/- 3.2 cm H2O to 18.8 +/- 5.2 cm H2O, p < 0.01). The pH increase (CA) from 7.18 +/- 0.06 to 7.40 +/- 0.09 caused the PAP to decrease (18.8 +/- 5.2 cm H2O to 15.9 +/- 4.2 cm H2O); the fluid filtration rate remained unchanged during the whole experiment. It is concluded that blood pH changes at constant PCO2 result in significant changes of PAP. Acidemia produces pulmonary vasoconstriction, which may be a contributing factor in the genesis of pulmonary hypertension in clinical conditions with increased hydrogen ion concentration [H+].

[Colonic tumors: experience at a clinical center in Caracas]. / Tumores de colon: experiencia en un centro clínico de Caracas.

During a period of six years, 33.452 histopathological studies were reviewed among which were found 285 cases with malignant neoplasm of the colon. 69% of the patients were between fifty and sixty years of age. The diagnosis of colonic adenocarcinoma was positive in 90.17% of the cases. 58.9% of the tumors were localized in the rectum and sigmoid. The remaining 41.06% of the tumors were not subject to rectosigmoidoscopy. The epidemiological analysis was made. Most of the patients were found with locally advanced cancer with a predominance of poor differentiated tumours, which represents a complex challenge to the surgeon.

[Effect of the administration of intralipid on liquid filtration rate and pressure of the pulmonary artery in isolated lung of rabbits]. / Efecto de la administración de Intralipid en la tasa de filtración de líquido y en la presión de la arteria pulmonar en el pulmón aislado de conejo.

INTRODUCTION: We study the effect on Intralipid on pulmonary circulation. METHODS: A 10% infusion of Intralipid was administered at a dose of 0.5/kg in 14 isolated rabbit lungs in which constant blood flow infusion was carried out principally in zone 3. The liquid filtration rate (LFR) and the mean pressure of the pulmonary artery were measured. RESULTS: A constant increase of mean pressure of the pulmonary artery was observed following the infusion (from 12.32 +/- 3.66 cm of H2O to 39.92 +/- 07.68 cmH2O (p < 0.01) which was associated to a significant increase in the rate of liquid filtration (from 0.018 +/- 0.01 g/min to 0.198 +/- 0.04 g/min; p < 0.01). CONCLUSIONS: The administration of Intralipid produces a statistically significant increase of mean pressure of the pulmonary artery and the rate of liquid filtration. This is probably caused by vasoconstriction due to metabolic changes produced by Intralipid on pulmonary circulation.

[Juvenile dermatomyositis. Clinical and epidemiologic experience]. / Dermatomiositis juvenil. Experiencia clínica y epidemiológica.

27 cases with a diagnosis of Juvenile Dermatomyositis were studied from a total of 1307 patients who suffered from connective tissue diseases; 19 of which met the diagnosis criteria of Bohan and Peters. Females were the most frequently affected. 52.63% of the cases presented the first symptoms between 5 and 9 years of age. Skin lesions, debility in inferior extremities and fever were the most frequent motives of consultation. The Aldolase and LDH were the muscular enzymes whose values increased in the majority of the cases. The electromyography was more sensible than the muscular biopsy in the diagnosis of the disease. We suggest that the epidemiologic and clinical characteristics found in our study should be taken into account for further accurate diagnosis of Juvenile Dermatomyositis in Venezuela.