Table 1 Anatomical and physiological study variables collected at baseline, according to RIFLE classification
Variable | NO AKI (n: 27) | RIFLE 1: risk (n: 18) | RIFLE 2: injury (n: 18) | RIFLE 3: failure (n: 15) | p-value |
|---|---|---|---|---|---|
Baseline characteristics | |||||
Initial weight (Kg) | 24.4 (± 2.3) | 23.2 (± 2.2) | 23.1 (± 1.7) | 24.2 (± 2.2) | 0.142 |
Functional residual capacity (mL) | 352 (± 64) | 348 (± 66) | 363 (± 61) | 380 (± 49) | 0.436 |
Respiratory variables | |||||
Tidal volume (mL) | 243 (± 25) | 230 (± 27) | 241 (± 29) | 220 (± 25) | 0.038 |
Respiratory rate (bpm) | 21 (± 4) | 21 (± 2) | 20 (± 3) | 21 (± 3) | 0.894 |
Mean airway pressure (cmH2O) | 9.8 (± 2.1) | 9.1 (± 0.9) | 9.5 (± 1.7) | 9.3 (± 1.2) | 0.467 |
PEEP measured (cmH2O) | 5.4 (± 0.7) | 5.4 (± 0.3) | 5.3 (± 0.3) | 5.7 (± 1.3) | 0.541 |
Mean pleural pressure (cmH2O) | 4.3 (± 1.3) | 4.1 (± 1.6) | 4.5 (± 1.7) | 4.3 (± 1.3) | 0.866 |
Driving pressure (cmH2O) | 3.3 (± 1.4) | 3.0 (± 1.0) | 3.1 (± 0.8) | 2.7 (± 0.8) | 0.538 |
Stress-Transpulmonary pressure (mmHg) | 5.15 (± 1.61) | 4.57 (± 1.62) | 4.82 (± 1.84) | 4.3 (± 2.29) | 0.513 |
Strain, fraction | 0.71 (± 0.14) | 0.68 (± 0.11) | 0.68 (± 0.15) | 0.59 (± 0.10) | 0.045 |
Airway resistance (cmH2O*min/L) | 0.18 (± 0.05) | 0.20 (± 0.08) | 0.18 (± 0.05) | 0.17 (± 0.03) | 0.405 |
Elastance, respiratory system (cmH2O/mL) | 39.0 (± 6) | 38.4 (± 6.0) | 39.6 (± 7.9) | 40.0 (± 9.8) | 0.926 |
Elastance, lung (cmH2O/mL) | 21.80 (± 6.65) | 21.36 (± 8.17) | 20.08 (± 6.23) | 21.75 (± 8.45) | 0.877 |
Elastance, chest-wall (cmH2O/mL) | 17.10 (± 4.96) | 17.07 (± 6.43) | 19.48 (± 5.01) | 18.30 (± 7.39) | 0.530 |
Specific elastance | 7.28 (± 1.90) | 6.82 (± 2.30) | 7.05 (± 1.65) | 7.39 (± 3.42) | 0.892 |
Mechanical power, respiratory system (J/min) | 6.7 (± 2.0) | 6.0 (± 1.3) | 6.3 (± 1.6) | 5.9 (± 1.4) | 0.393 |
Mechanical power, lung (J/min) | 4.42 (± 1.77) | 3.94 (± 1.21) | 3.99 (± 1.28) | 3.77 (± 1.11) | 0.480 |
Hemodynamic | |||||
Heart rate (bpm) | 98 (± 19) | 98 (± 21) | 100 (± 13) | 95 (± 20) | 0.964 |
Mean arterial pressure (mmHg) | 77 (± 9) | 70 (± 8) | 73 (± 4) | 73 (± 5) | 0.070 |
Central venous pressure (mmHg) | 8 (± 3) | 7 (± 3) | 8 (± 5) | 6 (± 1) | 0.470 |
Mean perfusion pressure (mmHg) | 70 (± 9) | 63 (± 6) | 65 (± 9) | 67 (± 4) | 0.150 |
Mean pulmonary artery pressure (mmHg) | 21 (± 4) | 18 (± 2) | 21 (± 4) | 19 (± 3) | 0.254 |
Cardiac output (L/min) | 3.98 (± 0.72) | 3.81 (± 0.91) | 4.6 (± 0.66) | 4.07 (± 0.62) | 0.219 |
Central venous oxygen saturation (%) | 84 (± 5) | 85 (± 4) | 89 (± 3) | 87 (± 3) | 0.065 |
Lactates (mg/dL) | 0.57 (± 0.20) | 0.57 (± 0.21) | 0.68 (± 0.63) | 1.29 (± 2.69) | 0.592 |
Blood gas analysis | |||||
PaO2 (mmHg) | 227 (± 11) | 231 (± 23) | 232 (± 15) | 227 (± 16) | 0.840 |
PaCO2 (mmHg) | 44 (± 5) | 44 (± 3) | 44 (± 4) | 43 (± 4) | 0.977 |
pH | 7.51 (± 0.05) | 7.52 (± 0.03) | 7.47 (± 0.06) | 7.52 (± 0.04) | 0.274 |