Figure 1.
Diagram of ventilation Strategies A, B and C.
Plethysmograph and airway pressure recordings of pups that were ventilated from birth using each of the PEEP Strategies A, B or C.
Figure 2.
Changes in FRC, VT and VPIP during ventilation with Strategy A.
Distribution of ventilation (A) at functional residual capacity (FRC), (B) of the incoming tidal volume (VT) and (C) volume at peak inflation pressure (VPIP) in the upper right (open triangles), upper left (closed triangles), lower right (open circles) and lower left (closed circles) regions of the lung during ventilation with Strategy A. Asterisks (*) indicate that UR quadrant is significantly different to the lower quadrants. Double asterisks (**) indicate that the upper quadrants are significantly different to the lower quadrants. Values are significantly different if p<0.05. Lower case letters (w-z) correspond to when phase contrast X-ray images of lung aeration at FRC and at VPIP were acquired.
Figure 3.
Changes in FRC, VT and VPIP during ventilation with Strategy B.
Distribution of ventilation (A) at functional residual capacity (FRC), (B) of the incoming tidal volume (VT) and (C) volume at peak inflation pressure (VPIP) in the upper right (open triangles), upper left (closed triangles), lower right (open circles) and lower left (closed circles) regions of the lung during ventilation with Strategy B. Asterisks (*) indicate that UR quadrant is significantly different to the lower quadrants. Double asterisks (**) indicate that the upper quadrants are significantly different to the lower quadrants. Daggers (†) indicate that UR quadrant is significantly different to all other quadrants. Section symbol (§) indicates that the LL quadrant is significantly different to all other quadrants. Values are significantly different if p<0.05. Lower case letters (w-z) correspond to when phase contrast X-ray images of lung aeration at FRC and at VPIP were acquired.
Figure 4.
Changes in FRC, VT and VPIP during ventilation with Strategy C.
Distribution of ventilation (A) at functional residual capacity (FRC), (B) of the incoming tidal volume (VT) and (C) volume at peak inflation pressure (VPIP) in the upper right (open triangles), upper left (closed triangles), lower right (open circles) and lower left (closed circles) regions of the lung during ventilation with Strategy C. Asterisks (*) indicate that UR quadrant is significantly different to the lower quadrants. Double asterisks (**) indicate that the upper quadrants are significantly different to the lower quadrants. Daggers (†) indicate that UR quadrant is different to all other quadrants. Values are significantly different if p<0.05. Lower case letters (w-z) correspond to when phase contrast X-ray images of lung aeration at FRC and at VPIP were acquired.
Figure 5.
Changes in VT and FRC during decreasing PEEP.
The increase in tidal volume (VT) and decrease in functional residual capacity (FRC) when positive end-expiratory pressure (PEEP) is decreased in 5 cmH2O stepwise decrements (10-5-0PEEP), large steps (10-0PEEP) and from a small step (5-0PEEP) in the ventilated lung. Asterisks (*) indicate that values during 5-0PEEP are significantly different to their corresponding quadrant during 10-5-0PEEP and 10-0PEEP. Double asterisks (**) indicate that values during 10-5-0PEEP are significantly different to their corresponding quadrant during 10-0PEEP. Daggers (†) indicate that values during 5-0PEEP are significantly different to their corresponding quadrant during 10-0PEEP. Values are significantly different if p<0.05. There was no significant difference between quadrants within any group.
Figure 6.
Changes in lung compliance in ventilation strategies A, B and C.
Lung compliance of each quadrant (upper left (UL), upper right (UR), lower left (LL) and lower right (LR)) compared between Strategy A (closed circles), Strategy B (open circles) and Strategy C (closed triangles). The x-axis demonstrates the timing and sequence of PEEP change for each strategy. Hashes (#) indicate that Strategy A was significantly different to Strategy B and C. Double hashes (##) indicate that Strategy A was different only to Strategy C. Values are significantly different if p<0.05.