Background : Respiratory workload increment in the process of mechanical ventilation withdrawal is critical for the determination of weaning outcome. Pressure, tidal volume (Vt) and respiratory rate (RR ) are considered as patient’s respiratory power, albeit being affected by excessive respiratory load. We aimed to evaluate the performance of driving pressure (DP)×RR to predict the outcome of weaning.
Methods : Plateau pressure (Pplat) and positive end-expiratory pressure tot (PEEPtot) were measured during mechanical ventilation, viz., (1) brief deep sedation, (2) on volume support ventilation of MV with Vt 6 ml/kg and a PEEP of 0 cm H 2 O, (3) Pplat and PEEPtot were measured by holding breath for 2s after inhalation and exhalation, respectively. The DP was determined as Pplat minus PEEPtot. The highest RR was recorded within 3 min during spontaneous-breathing trial (SBT). Patients that were able to tolerate SBT for 1 h were directly extubated .
Results : Out of the 61 patients studied, 22 failed weaning. During the withdrawal of ventilation, DP×RR was 134.2±33.2 cmH 2 O ·breaths/min and 238.5±61.7 cmH 2 O·breaths/min ( P =0.00), DP was 7.9±1.6 cmH 2 O and 9.7±2.3 cmH 2 O ( P =0.00), in the “success” and “failure” groups, respectively. The DP×RR index greater than 170 cmH 2 O·breaths/min had a sensitivity of 95.5% and a specificity of 89.7%, while DP index greater than 8.1 cmH 2 O had 81.8% sensitivity and 64.1% specificity to predict weaning failure.
Conclusions : Measurement of DP×RR during withdrawal of ventilation may help predict weaning outcome. Noticeably, high DP×RR increased the likelihood of weaning failure.