Reference equations for the 6-minute walk distance in healthy Portuguese subjects 18-70 years old.

INTRODUCTION: Six-minute walk test (6MWT) is used for evaluating functional exercise capacity. To the best of our knowledge, there are no reference equations to predict six-minute walk distance (6MWD) for the Portuguese population. The aims of the present study were to measure anthropometric data and 6MWD in a sample of healthy Portuguese population, to establish reference equations to predict 6MWD and to compare our equations with those obtained by previously published studies. METHODS: We conducted an observational prospective study. We consecutively recruited 158 healthy 18-70 years old subjects from Porto district, who performed two 6MWTs using a standardized protocol. The best 6MWD was used for further analysis. RESULTS: The mean 6MWD was 627.8m (SD=73.3m). The variables that were significantly associated with the 6MWD were age, sex, BMI and ΔHR (Heart Rateat the end of the test-HRat rest). We found three explanatory models for 6MWD, the best with an explanatory power of 38%: 6MWD=721.7-1.6×Age-4.0×BMI+0.9×ΔHR+58.4×Sex. We verified that 6MWD decreased 1.6m per year of age, and 4.0m per unit of BMI and increased 0.892m per beat per minute. Moreover, on average, males walk 58.4m more than females (p<0.001). Applying equations from other studies to our population resulted in an overestimation or underestimation of the 6MWD. CONCLUSION: The present study was the first to describe the 6MWD in healthy Portuguese people aged 18-70 years old and to propose predictive equations. These can contribute to improving the evaluation of Caucasian Mediterranean patients with diseases that affect their functional capacity.

Transbronchial lung cryobiopsy: Associated complications.

INTRODUCTION: Transbronchial lung cryobiopsy (TBC) has emerged as a diagnostic alternative to surgical lung biopsy in interstitial lung disease (ILD). Despite its less invasive nature, some associated complications have been described. OBJECTIVE: To evaluate complications of TBC and associated factors. METHODS: Prospective evaluation of all patients with ILD submitted to TBC in our centre. Clinicodemographic variables and factors associated to TBC complications were analyzed. The effect of the variables on the complication risk was evaluated by a logistic regression model. RESULTS: Ninety patients were included (mean age 60±13 years; 58.9% male). Twenty-two patients presented pneumothorax, 18 (81.8%) of which were treated with chest tube drainage [median air leak time: 1 day (IQR=2)]. Grade 2 and 3 bleeding was observed in 13 (14.4%) cases. Presence of visceral pleura in the sample accounted for almost more than 10 times the odds of pneumothorax (OR=9.59, 95% CI 2.95-31.17, p<0.001). Increased body mass index (BMI) was associated with bleeding (16% additional odds for each BMI unit increase (OR=1.16, 95% CI 1.01-1.34, p=0.049). CONCLUSION: The most frequent complication of TBC was pneumothorax, although rapidly reversible. There was a positive association between pneumothorax and the presence of pleura in the biopsy samples as well as between bleeding and increased BMI. More studies about TBC complications are needed to improve the selection of the candidates for this procedure.

Hematological evaluation in males with obstructive sleep apnea before and after positive airway pressure.

Obstructive sleep apnea syndrome (OSAS) is a systemic inflammatory disease associated with cardiovascular consequences. Red blood cell distribution width (RDW), mean platelet volume (MPV), and platelet distribution width (PDW) are recognized biomarkers of cardiovascular morbidity/mortality. Limited data is available on the association between these parameters and OSAS severity and the relationship with positive airway pressure therapy (PAP). In this prospective study of male OSAS patients we analyzed hematological data in order to evaluate their value in predicting OSAS severity, the relationship with sleep parameters, and their behavior under PAP. Seventy-three patients were included (mean age 46.5 years), of which 36 were mild (49.3%), 10 moderate (13.7%), and 27 severe (37%). The mean RDW increased significantly with OSAS severity and showed a positive correlation with respiratory disturbance index and hypoxemic burdens. Additionally, a group of 48 patients (mean age 47.2 years) were submitted to PAP. After six months, red blood cell count, hemoglobin, hematocrit, and platelet count showed a significant decrease (p<0.0001; p<0.0001; p=0.001; p<0.0001; respectively). Concerning OSAS severity, these parameters also significantly decreased in mild patients (p=0.003; p=0.043; p=0.020; p=0.014; respectively) but only hemoglobin, hematocrit, and platelet count decreased in severe cases (p<0.0001; p=0.008; p=0.018; respectively). This study demonstrated an association between RDW values and OSAS severity. Moreover, red cell and platelet parameters changed significantly after PAP, supporting its cardiovascular protective effect. RDW may become a simple/inexpensive blood biomarker, making it useful in prioritizing OSAS patients waiting for polysomnography, and red cell and platelet parameters could be useful in PAP follow up.