Respiratory physiology & neurobiology
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Respir Physiol Neurobiol · Aug 2007
Verbal numerical scales are as reliable and sensitive as visual analog scales for rating dyspnea in young and older subjects.
This study compared the use of a simple verbal 0-10 numerical rating scale (verbal NRS) and a visual analog scale (VAS) for the rating of dyspnea during exercise in a group of young and older subjects. Twelve younger (32+/-9 yr) and 12 older (71+/-7 yr) subjects used either the verbal NRS or the VAS in a randomised fashion to rate dyspnea during 60 s of uphill treadmill walking (range 5.6-8.8 km h(-1)) performed at either a low (17% grade) or high workload (26% grade) and then during recovery. Rating scales were evaluated twice on separate days (day 1 and day 2) at each workload. ⋯ Overall, subjects preferred the verbal NRS to the VAS. These results suggest that the verbal NRS compares favourably with the VAS for rating dyspnea during exercise without mask or mouthpiece. However, when rating peak dyspnea both scales appear less reliable when used by the older compared to young subjects.
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Respir Physiol Neurobiol · Aug 2007
The contribution of the pulmonary microvascular pressure in the maintenance of an open lung during mechanical ventilation.
Changes in pulmonary hemodynamics modify the mechanical properties of the lungs. The effects of alterations in pulmonary capillary pressure (Pc) were investigated on the airway and lung tissue mechanics during positive-pressure ventilation and following lung recruitment maneuvers. Isolated, mechanically normoventilated (PEEP 2.5 cmH(2)O) rat lungs were perfused with Pc set to 0 (unperfused), 5, 10 or 15 mmHg, in random sequence. ⋯ The changes in the oscillatory mechanics were also reflected in E and the hysteresis of the P-V curves. These findings indicate that pulmonary hypoperfusion during mechanical ventilation forecasts a parenchymal mechanical deterioration. Physiological pressure in the pulmonary capillaries is therefore an important mechanical factor promoting maintenance of the stability of the alveolar architecture during positive-pressure mechanical ventilation.