Very early passive cycling exercise in mechanically ventilated critically ill patients: physiological and safety aspects--a case series.

INTRODUCTION: Early mobilization can be performed in critically ill patients and improves outcomes. A daily cycling exercise started from day 5 after ICU admission is feasible and can enhance functional capacity after hospital discharge. In the present study we verified the physiological changes and safety of an earlier cycling intervention (< 72 hrs of mechanical ventilation) in critical ill patients. METHODS: Nineteen hemodynamically stable and deeply sedated patients within the first 72 hrs of mechanical ventilation were enrolled in a single 20 minute passive leg cycling exercise using an electric cycle ergometer. A minute-by-minute evaluation of hemodynamic, respiratory and metabolic variables was undertaken before, during and after the exercise. Analyzed variables included the following: cardiac output, systemic vascular resistance, central venous blood oxygen saturation, respiratory rate and tidal volume, oxygen consumption, carbon dioxide production and blood lactate levels. RESULTS: We enrolled 19 patients (42% male, age 55 ± 17 years, SOFA = 6 ± 3, SAPS3 score = 58 ± 13, PaO2/FIO2 = 223 ± 75). The median time of mechanical ventilation was 1 day (02), and 68% (n=13) of our patients required norepinephrine (maximum concentration = 0.47 µg.kg(-1).min(-1)). There were no clinically relevant changes in any of the analyzed variables during the exercise, and two minor adverse events unrelated to hemodynamic instability were observed. CONCLUSIONS: In our study, this very early passive cycling exercise in sedated, critically ill, mechanically ventilated patients was considered safe and was not associated with significant alterations in hemodynamic, respiratory or metabolic variables even in those requiring vasoactive agents.

Effects of São Paulo air pollution on the upper airways of mice.

The nose is the first region of the respiratory tract to come in contact with airborne pollutants. Previous studies have shown that the nasal mucosa can be altered in response to air pollution. In this study, we quantified neutral and acidic mucus in three different levels of the nasal cavity of mice exposed to ambient levels of air pollution in the city of São Paulo, Brazil. Two groups of 6-day-old male Swiss mice were placed in two exposure chambers. Mice were maintained in the chambers 24 h/day, 7 days/week for 5 months. The first chamber contained an air filter device (clean chamber; n=20), whereas the second one received ambient air pollution (polluted chamber; n=20). We measured the concentration of PM(2.5), nitrogen dioxide (NO2), and black carbon inside both chambers. The nasal cavity was transversely sectioned at three specific anatomic locations (proximal, medial, and distal levels) and submitted to quantitative analysis of the amounts of neutral and acidic mucosubstances. We observed a 37.85% decrease in NO2, 54.77% decrease in PM(2.5), and 100% decrease in black carbon concentration in the clean chamber compared to the polluted chamber. Significant differences between polluted and clean chambers were observed in the epithelium lining the septum of proximal and medial levels of the nasal mucosa, with an increase in the percentage of acidic mucus in the polluted chamber (P=0.037, proximal level; P=0.023, medial level). We conclude that prolonged exposure to low levels of ambient air pollution from an early age shows evidence of causing secretory changes in the nasal cavity of mice, with increased production of acidic mucosubstances.