F(E(P))." In both groups the inequality applied, since F(P) defines volume in the Venegas equation and (P) pressure and the range of VTs varied within the convex interval for individual P-V curves. Over 5 hrs, there were no significant differences between groups in minute ventilation, airway pressure, blood gases, haemodynamics, respiratory compliance or IL-8 concentrations. Conclusion No difference between groups is a consequence of BVV occurring on the convex interval for individualised Venegas P-V curves in all experiments irrespective of group. Jensen's inequality provides theoretical proof of why a variable ventilatory approach is advantageous under these circumstances. When using BVV, with VT centred by Venegas P-V curve analysis at the point of maximal compliance change, some leeway in low VT settings beyond ARDSNet protocols may be possible in acute lung injury. This study also shows that in this model, the standard ARDSNet algorithm assures ventilation occurs on the convex portion of the P-V curve."/>
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Table 2 Respiratory Gases and Mechanics

From: Mathematical modelling to centre low tidal volumes following acute lung injury: A study with biologically variable ventilation

  Pre OA Post OA Post PV Curve 1 hr 5 hr
PaO2      
   Control Group 265 ± 23 * 101 ± 15 113 ± 9 147 ± 46 * 176 ± 36 *
   Experimental Group 267 ± 19 * 89 ± 16 100 ± 45 139 ± 59 * 163 ± 62 *
PaCO2      
   Control Group 38 ± 4 * 48 ± 5 56 ± 9 57 ± 7 51 ± 5
   Experimental Group 38 ± 2 * 48 ± 7 53 ± 10 54 ± 21 49 ± 12
PvO2      
   Control Group 43 ± 4 * 35 ± 3 38 ± 2 37 ± 5 35 ± 4
   Experimental Group 48 ± 5 * 38 ± 5 37 ± 5 39 ± 7 36 ± 6
pHa      
   Control Group 7.45 ± 0.04 * 7.34 ± 0.04 7.30 ± 0.07 7.29 ± 0.06 7.35 ± 0.04
   Experimental Group 7.45 ± 0.03 * 7.33 ± 0.04 7.30 ± 0.08 7.30 ± 0.08 7.35 ± 0.07
Crs      
   Control Group 1.15 ± 0.17 * 0.66 ± 0.12 0.58 ± 0.12 0.55 ± 0.13 0.61 ± 0.11
   Experimental Group 1.11 ± 0.17 * 0.70 ± 0.22 0.58 ± 0.17 0.60 ± 0.16 0.68 ± 0.18
  1. PaO2 = Arterial Partial Pressure O2 (mmHg)
  2. PaCO2 = Arterial Partial Pressure CO2 (mmHg)
  3. PvO2 = Mixed Venous Partial Pressure O2 (mmHg)
  4. pHa = Arterial pH
  5. Crs = Compliance L/cmH2O
  6. * p < .05 Within Groups vs Post PV Curve
  7. Control Group n = 11 Mean ± SD
  8. Experimental Group n = 11 Mean ± SD