Intensive care medicine experimental
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Intensive Care Med Exp · Dec 2014
Unilateral mechanical asymmetry: positional effects on lung volumes and transpulmonary pressure.
Ventilated patients with asymmetry of lung or chest wall mechanics may be vulnerable to differing lung stresses or strains dependent on body position. Our purpose was to examine transpulmonary pressure (P TP) and end-expiratory lung volume (functional residual capacity (FRC)) during body positioning changes in an animal model under the influence of positive end-expiratory pressure (PEEP) or experimental pleural effusion (PLEF). ⋯ FRC did not differ among horizontal positions; however, semi-Fowler's positioning significantly raised FRC. P TP proved insensitive to mechanical asymmetry. While end-expiratory P TP was negative at PEEP1, applying PEEP10 caused a transition to positive P TP, suggestive of reopening of initially compressed lung units.
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Intensive Care Med Exp · Dec 2014
Moderately high frequency ventilation with a conventional ventilator allows reduction of tidal volume without increasing mean airway pressure.
The aim of this study was to explore if positive-pressure ventilation delivered by a conventional ICU ventilator at a moderately high frequency (HFPPV) allows a safe reduction of tidal volume (V T) below 6 mL/kg in a porcine model of severe acute respiratory distress syndrome (ARDS) and at a lower mean airway pressure than high-frequency oscillatory ventilation (HFOV). ⋯ During protective mechanical ventilation, HFPPV delivered by a conventional ventilator in a severe ARDS swine model safely allows further tidal volume reductions. This strategy also allowed decreasing airway pressures while maintaining stable PaCO2 levels.