The effect of body warming on respiratory mechanics in rats

The effect of angiotensin-converting enzyme inhibition by captopril on respiratory mechanics in healthy rats

“…Static pressure-volume relationships were assumed to be linear up to an inflation volume of 3 mL. This measurement is in agreement with published data showing essentially linear pressure-volume relationships for the rat respiratory system within this volume range 16,24,26,31 . The validity of this assumption has also been confirmed experimentally by the essentially linear pressure-volume relationships observed during static inflations performed for H y,rs measurements up to a total inflation volume of 5 mL (see below).…”

“…Positive pressure ventilation was maintained for 10 min and respiratory mechanics were then measured using the end-inflation occlusion method [13][14][15][16] . The ventilator was disconnected, PEEP was discontinued, and the tracheal cannula was connected to a constant flow pump (SP 2000 Series Syringe Pump sp210iw, World Precision Instruments, USA) set to deliver a tidal volume (VT) of 3 mL with a square wave flow (F) of 4 mL/s.…”

“…The work of breathing (WOB rs ) values were calculated as previously described 16,24,25 , and outlined in Figure 2. Static pressure-volume relationships were assumed to be linear up to an inflation volume of 3 mL.…”

“…These may be easily measured, together with the ohmic airway resistance, by the end-inflation occlusion method [13][14][15][16] , which has never been applied to study the angiotensin's effects on respiratory mechanics.…”

“…Due to their viscoelastic properties, the tissues do not maintain constant stress under constant deformation, but slowly relax. The viscoelastic pressure component of the inspiratory work of breathing contributes significantly to the overall breathing pressure dissipation [13][14][15][16] . Hence, the study of the factors possibly affecting stress relaxation has practical connotations, because any effect reducing the viscoelastic component of the inspiratory work of breathing may suggest therapeutical implications.…”