Evidence suggests that mechanical power (MP) normalized to dynamic compliance, which equals power density, may help identify prolonged ventilated patients at risk for spontaneous breathing trial (SBT) failure. This study compared MP density with traditional spontaneous breathing indexes to predict a patient's capacity to sustain a short trial of unassisted breathing.

A prospective observational study on 186 prolonged ventilated, tracheotomized patients. We analyzed the first 30-min SBT upon weaning center admission, comparing MP density with spontaneous breathing indexes (e.g., predicted body weight normalized tidal volume (VT/PBW), rapid shallow breathing index (RSBI), and the integrative weaning index (IWI)) regarding SBT failure prediction, with diagnostic accuracy expressed as the area under the receiver operating characteristic curve (AUROC).

SBT failure occurred in 51 out of 186 patients (27 %), who demonstrated significantly lower dynamic compliance (median 29 mL/cmH₂O [IQR 26–37] vs. 39 mL/cmH₂O [33–45]) and higher MP density (5837 cmH₂O²/min [4512–7758] vs. 2922 cmH₂O²/min [2001–4094]) before SBT, as well as lower spontaneous VT/PBW (5.7 mL∗kg⁻¹ [5.0–6.7] vs. 6.6 mL∗kg⁻¹ [5.9–7.8]), higher RSBI (73 min⁻¹∗L⁻¹ [57–100] vs. 59 min⁻¹∗L⁻¹ [45–76]), and lower IWI (40 L²/cmH₂O∗%∗min∗10⁻³ [27–50] vs. 63 L²/cmH₂O∗%∗min∗10⁻³ [46–91]) after 5 min of unassisted breathing. MP density was more accurate at predicting SBT failures (AUROC 0.86 [95%CI 0.80–0.91]) than VT/PBW (0.58 [0.50–0.65]), RSBI (0.54 [0.47–0.61]), or IWI (0.66 [0.58–0.73])).

MP density as a readiness criterion was more accurate at predicting weaning trial failures in prolonged ventilated, tracheotomized patients than traditional indexes assessed during unassisted breathing.