Table 4– Physiological variables, haemodynamic support and organ failure assessment for days 1–10 post-randomisation
VariableBaselineDay 1Day 5Day 10Missing values %p-value
GroupTimeGroup×time
Tidal volume<0.001<0.001<0.001
 L
  HFO-TGI group0.46±0.050.46±0.050.47±0.060.50±0.0715.2
  CMV group0.45±0.060.44±0.060.45±0.050.46±0.0718.2
 mL·kg−1 PBW
  HFO-TGI group6.5±0.66.4±0.66.7±0.7§7.2±1.2*,+,§,ƒ15.2
  CMV group6.5±0.56.4±0.56.3±0.46.4±0.618.2
Ventilation rate breaths·min−10.046<0.0010.003
 HFO-TGI group27.6±4.327.8±4.427.6±4.326.0±5.215.2
 CMV group27.2±5.327.2±5.328.2±3.827.6±5.518.2
Peak pressure cmH2O0.46<0.001<0.001
 HFO-TGI group43.4±6.142.5±5.5*39.6±7.4+,§35.3±9.5+,§15.2
 CMV group41.2±5.639.5±5.3+39.8±6.037.2±7.018.2
aw cmH2O0.41<0.0010.001
 HFO-TGI group21.7±2.921.6±2.9*18.9±2.8+,§16.7±4.2*,+,§15.2
 CMV group20.3±3.319.7±3.019.6±3.217.9±3.118.8
Plateau pressure cmH2O<0.001<0.001<0.001
 HFO-TGI group30.9±4.230.7±4.226.3±3.2*,+,§24.0±5.6*,+,§15.2
 CMV group29.9±3.029.7±3.129.3±4.527.4±4.118.2
External PEEP cmH2O0.81<0.0010.03
 HFO-TGI group14.3±2.514.2±2.512.0±2.6+,§10.1±3.0+,§,ƒ15.2
 CMV group13.1±3.012.9±3.312.1±3.210.5±2.8+,§18.2
Compliance mL·cmH2O−1<0.001<0.001<0.001
 HFO-TGI group30.3±8.130.4±8.237.6±9.8*,+,§43.3±11.8*,+,§15.2
 CMV group28.8±5.328.3±5.528.4±6.630.0±8.918.2
FI,O2 %0.57<0.0010.007
 HFO-TGI group81.9±13.981.6±13.8*65.0±12.7+,§57.2±15.8+,§8.3
 CMV group76.1±14.274.1±14.869.5±17.361.3±17.9+,§15.8
Pa,O2 mmHg<0.001<0.001<0.001
 HFO-TGI group75.5±17.777.9±19.5108.0±37.4*,+,§114.8±37.9*,+,§8.3
 CMV group78.2±12.778.5±12.785.4±22.890.1±28.615.8
Pa,O2/FI,O2 mmHg0.007<0.001<0.001
 HFO-TGI group96.5±31.399.5±31.6175.2±74.1*,+,§222.9±108.1*,+,§8.3
 CMV group106.9±27.7110.5±28.2135.0±61.6163.5±76.115.8
Oxygenation index0.21<0.0010.01
 HFO-TGI group26.4±13.525.6±13.413.6±7.7*,+,§12.6±15.1+,§15.2
 CMV group21.1±8.919.9±8.819.1±10.314.7±8.818.8
Pa,CO2 mmHg0.030.0480.14
 HFO-TGI group47.6±8.447.2±8.246.9±8.346.3±10.78.3
 CMV group47.5±8.047.4±8.050.0±9.950.3±18.9+,§15.8
pHa0.001<0.001<0.001
 HFO-TGI group7.33±0.077.33±0.077.39±0.07+,§7.40±0.07*,+,§8.3
 CMV group7.30±0.087.31±0.087.36±0.09+,§7.36±0.0815.8
Shunt fraction0.02<0.001<0.001
 HFO-TGI group0.46±0.120.45±0.130.29±0.12*,+0.26±0.15*,+8.3
 CMV group0.42±0.090.42±0.090.37±0.130.33±0.1315.8
MAP mmHg0.160.02<0.001
 HFO-TGI group81.7±13.279.9±13.581.5±11.983.4±9.58.3
 CMV group77.3±11.079.1±11.982.4±9.780.1±12.815.8
CVP mmHg0.89<0.0010.63
 HFO-TGI group10.8±4.111.7±4.2+11.3±3.410.3±3.18.3
 CMV group10.1±3.410.8±3.6+11.8±4.211.4±4.515.8
Heart rate beats·min−10.580.020.31
 HFO-TGI group98.9±18.996.6±19.890.1±17.4+95.9±14.98.3
 CMV group98.9±16.797.7±16.692.3±14.293.4±15.415.8
Cardiac index L·min−1·m−20.12<0.0010.65
 HFO-TGI group4.0±1.034.0±1.03.7±0.93.8±0.512.9
 CMV group4.1±0.94.2±0.84.0±0.74.1±1.021.1
DO2I mL·min−1·m−20.46<0.0010.18
 HFO-TGI group460.0±122.7475.3±133.5+431.3±105.5443.3±116.812.9
 CMV group489.8±134.8495.7±130.0444.9±81.6§419.8±78.1+,§21.1
Scv,O2 %0.140.090.30
 HFO-TGI group70.7±8.871.4±8.572.8±5.871.6±8.78.3
 CMV group70.7±6.671.0±6.771.0±6.071.9±4.315.8
Lactate mmol·L−10.12<0.0010.32
 HFO-TGI group2.5±1.82.3±1.81.9±1.11.5±0.88.3
 CMV group2.8±2.82.8±2.52.2±2.11.6±0.815.8
Fluid balance# L·day−10.63<0.0010.47
 HFO-TGI group2.03±1.652.34±2.341.04±1.48§0.81±1.73§8.3
 CMV group2.07±1.712.56±2.041.07±1.55§0.72±1.68§15.8
Noradrenaline μg·kg−1·min−10.380.030.12
 HFO-TGI group0.19±0.160.22±0.230.15±0.130.09±0.118.3
 CMV group0.19±0.160.19±0.170.15±0.150.12±0.1615.8
SOFA score0.02<0.0010.03
 HFO-TGI group11.7±2.711.5±2.710.4±3.77.4±4.6*,+,§,ƒ8.3
 CMV group12.1±2.611.9±2.711.9±4.210.0±3.815.8
  • Data are presented as mean±sd, unless otherwise stated. Data originate from physiological measurements performed during conventional mechanical ventilation in each one of the 125 patients (intention-to-treat analysis), within 2 h before randomization (baseline), and between 09:00 and 10:00 h on days 1–10 post-randomisation. Detailed data on physiological endpoints and the Sequential Organ Failure Assessment (SOFA) score are presented in fig. 3. Pressure, volume and respiratory rate values were those displayed by the ventilator. Respiratory compliance was calculated as tidal volume divided by the end-inspiratory to end-expiratory plateau airway pressure difference [7, 12]. For both groups, analysed data corresponded to 11 consecutive time-points, i.e. at baseline and on the morning of each of the first 10 days post-randomisation. For between-group comparisons at each time-point, we used the Bonferroni correction, i.e. we multiplied the obtained p-values by 11. The 11 time-points resulted in a total of 55 within-group pairwise comparisons; thus, we multiplied p-values from within-group comparisons by 55. The handling of missing values is summarised in the online supplementary material. HFO: high-frequency oscillation; TGI: tracheal gas insufflation; CMV: conventional mechanical ventilation; PBW: predicted body weight; aw: mean airway pressure; PEEP: positive end-expiratory pressure; FI,O2: inspiratory oxygen fraction; Pa,O2: arterial oxygen tension; Pa,CO2: arterial carbon dioxide tension; pHa: arterial pH; MAP: mean arterial pressure; CVP: central venous pressure; DO2I: oxygen delivery index; Scv,O2: central venous oxygen saturation. #: baseline values correspond to the fluid balance of the preceding 24 h; other values correspond to the fluid balance of days 1, 5 and 10. : baseline infusion rate was the infusion rate recorded just prior to randomisation; other infusion rates are the average infusion rates of days 1, 5 and 10; during days 1–10, all patients of both groups required a noradrenaline infusion for ≥1 h to maintain a MAP of ≥70 mmHg. *: p<0.05 versus CMV group at that particular time-point; +: p<0.05 versus baseline; §: p<0.05 versus day 1; ƒ: p<0.05 versus day 5.