Bedside assessment of the effects of positive end-expiratory pressure on lung inflation and recruitment by helium dilution technique and electrical impedance tomography
Tommaso Mauri, Nilde Eronia, Cecilia Turrini, Marta Battistini, Giacomo Grasselli, Roberto Rona, Carlo Alberto Volta, Giacomo Bellani, Antonio Pesenti.
ONLINE DATA SUPPLEMENT
Table 1 online. Ventilation, lung inflation and recruitment at lower and higher PEEP in the ARDS patients subgroup (n=8).
Variable* / PEEPlow / PEEPhigh / P-value**PEEP (cmH2O) / 9 [8-10] / 14 [13-16] / 0.01
PaO2/FiO2 (mmHg) / 172 ± 55 / 186 ± 44 / 0.13
FiO2 / 0.50 [0.45-0.55] / 0.50 [0.45-0.55] / 1.00
Vt (mL/Kg PBW) / 6.8 [5.8-7.0] / 6.7 [5.8-7.0] / 0.69
Vt (mL) / 433 [316-488] / 435 [312-491] / 0.69
RR (bpm) / 22 [16-25] / 22 [16-25] / 1.00
MVe (L/min) / 9.2 ± 3.0 / 9.1 ± 3.0 / 0.18
Pplat (cmH2O) / 18 ± 3 / 24 ± 4 / <0.001
PaCO2 (mmHg) / 44 ± 5 / 46 ± 4 / 0.13
ΔEELVHe (mL) / Baseline / 547 ± 263 / <0.001
ΔEELVEIT (mL) / Baseline / 527 ± 244 / <0.001
RECRHe (mL) / Baseline / 309 ± 212 / 0.01
RECREIT (mL) / Baseline / 289 ± 188 / 0.01
*PEEP, positive end-expiratory pressure; PaO2/FiO2, oxygen partial arterial tension / inspired oxygen fraction; Vt, tidal volume; PBW, predicted body weight; RR, respiratory rate; MVe, expired minute ventilation; Pplat, plateau pressure; PaCO2, carbon dioxide partial arterial pressure; ΔEELVHe, change of end-expiratory lung volume at PEEPhigh measured by Helium dilution technique; ΔEELVEIT, change of end-expiratory lung volume measured by Electrical Impedance Tomography; RECRHe, lung recruitment assessed by Helium dilution technique; RECREIT, lung recruitment assessed by Electrical Impedance Tomography. Data are expressed as mean ± standard deviation for normally distributed variables and as median [interquartile range] for non-normally distributed ones.
**P-value by paired t-test or by Wilcoxon signed rank test, as appropriate.
Table 2 online. Regional effects of higher PEEP on the determinants of ventilation-induced lung injury in the ARDS patients subgroup (n=8).
Variable* / PEEPlow / PEEPhigh / P-value**RECREIT non-dep (mL) / Baseline / 200 ± 121 / 0.01
RECREIT dep (mL) / Baseline / 88 ± 94 / 0.03
Vtnon-dep (mL) / 284 ± 88 / 257 ± 81 / 0.001
Vtdep (mL) / 127 ± 36 / 151 ± 42 / 0.01
ITVHet / 2.3 [1.8-2.9] / 1.7 [1.5-2.5] / <0.01
VtHet / 2.1 [1.6-2.6] / 1.6 [1.3-2.4] / <0.01
Crs (mL/cmH2O) / 46 ± 17 / 43 ± 18 / 0.20
Crs non-dep (mL/cmH2O) / 32 ± 14 / 28 ± 14 / <0.01
Crs dep (mL/cmH2O) / 14 ± 9 / 15 ± 11 / 0.14
Tidal hyperinflation (%) / 8.6 ± 4.5 / 15.8 ± 4.8 / 0.01
Tidal hyperinflationnon-dep (%) / 4.2 ± 3.0 / 20.2 ± 6.1 / 0.001
Tidal hyperinflationdep (%) / 17.9 ± 11.6 / 7.3 ± 4.4 / 0.05
V/PHom / 0.26 ± 0.16 / 0.42 ± 0.27 / 0.01
V/PHom non-dep / 0.37 ± 0.20 / 0.54 ± 0.25 / <0.01
V/PHom dep / 0.16 ± 0.10 / 0.27 ± 0.10 / 0.31
* Vt, tidal volume; non-dep, non-dependent lung regions; dep, dependent lung regions; ITVHet ventilation distribution heterogeneity index intra-tidal; VtHet, ventilation distribution heterogeneity index at the end of inspiration; Crs, respiratory system compliance V/PHom, ventilation/perfusion homogeneity index. Data are expressed as mean ± standard deviation for normally distributed variables and as median [interquartile range] for non-normally distributed ones.
**P-value by paired t-test or by Wilcoxon signed rank test, as appropriate.
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