Table 2.
Ventilatory and respiratory mechanical parameters, dead spaces, blood gas and hemodynamic parameters (mean±SD) at the end of each study period.
| Tp0init | Tp20 | Tp0late | Friedman Test | |
|---|---|---|---|---|
| VT (ml) | 489±63 | 502±63* | 489±63 | <0.0001 |
| RR (min−1) | 18±4 | 18±4 | 18±4 | |
| Ti (s) | 0.7±0.2 | 1.4±0.3 | 0.7±0.2 | |
| Te (s) | 3.0±0.6 | 2.3±0.5 | 3.0±0.6 | |
| (Ti+Tp)/Ttot (%) | 20 | 40 | 20 | |
| Ppeak (cmH2O) | 31.5±5.7 | 31.3±5.4 | 31.3±5.6 | 0.4 |
| Pplat (cmH2O) | 21.7±4.5 | |||
| PEEPe (cmH2O) | 8.8±2.5 | 8.8±2.5 | 8.8±2.5 | |
| PEEPtot (cmH2O) | 9.1±2.5 | 9.5±2.6* | 9.1±2.5 | <0.0001 |
| VDphys% (%VT) | 68.2±7.4 | 60.8±8.8* | 67.6±7.6 | <0.0001 |
| VDaw% (%VT) | 40.3±8.8 | 33.4±8.8* | 40.4±8.7 | <0.0001 |
| VDaw (ml) | 194±40 | 166±41* | 195±39 | <0.0001 |
| VDalv% (%VT) | 23.8±9.1 | 22.8±10.1 | 22.9±8.6 | 0.4 |
| FiO2 | 0.8±0.2 | 0.8±0.2 | 0.8±0.2 | |
| pH | 7.27±0.07 | 7.31±0.08* | 7.27±0.08 | <0.0001 |
| PaCO2 (mmHg) | 55±10 | 49±9* | 55±10 | <0.0001 |
| PaO2 (mmHg) | 113±32 | 110±32 | 116±34 | 0.2 |
| PaO2/FiO2 ratio (mmHg) | 148±45 | 145±48 | 151±45 | 0.2 |
| MAP (mmHg) | 69±7 | 73±11 | 70±6 | 0.6 |
| HR (min−1) | 85±20 | 87±18 | 89±18 | 0.2 |
Values are mean±SD
p=0.001 Tp20 vs Tp0init or Tp0late
VT – tidal volume, RR – respiratory rate, Ti–inspiratory time including post-inspiratory pause, Te–expiratory time; Ti+Tp – insufflation and post-inspiratory pause as percent of the breathing cycle, PEEPe – external positive end expiratory pressure, PEEPtot – external positive end expiratory pressure + intrinsic positive end expiratory pressure, VDphys% – physiological dead space in percent of VT, VDaw% – airways dead space in percent of VT, VDalv% – alveolar dead space in percent of VT, FiO2 – fraction of inspired oxygen, MAP – mean arterial pressure, HR- heart rate.