16 18 23 24 31 34 For patients who had been ventilated for more than 72 hours, Marelich et al 18 used a stepwise reduction in positive end expiratory pressure, synchronised intermittent mechanical ventilation, and pressure support before the spontaneous breathing trial.
In the early days of mechanical ventilation, negative pressure ventilation was the dominant means of generating transpulmonary pressure.
The main mechanism of improvement of lung function by assisted mechanical ventilation using pressure support is not recruitment of dorsal areas, but rather redistribution of pulmonary blood flow to ventral zones.
The mechanical ventilation was pressure controlled (Servo 900 C; Siemens, Solna, Sweden), and ventilator settings were not altered during the study period.
Koksal and coworkers [ 17] compared plasma insulin, cortisol, glucose and urinary vanilmandelic acid in patients ventilated for more than 48 hours before, during and after liberation from mechanical ventilation using pressure support, CPAP, and T-piece (n = 20 each).
The cyclic change in the arterial pressure waveform during positive pressure mechanical ventilation as pulse pressure variation (dPP) has been proposed to identify responders to fluid administration.
Lung resistance (RL) and elastance (EL) were computed by linear regression fitting of recorded signals during mechanical ventilation (tracheal pressure, flow and volume).
MV mechanical ventilation, PSV pressure support ventilation.
Anesthesia was maintained with 2 2.5% sevoflurane, and mechanical ventilation by pressure control was maintained throughout the surgery.
In spontaneous breathing patients without mechanical ventilation, intrathoracic pressure decreases, while venous return and stroke volume increases during inspiration [10].
