Background: The primary aim of the study was to evaluate agreement between the automatically calculated mechanical power on the Mindray SV-600 ventilator (MPauto), and MP calculated using equations (MPcalc) across two tidal volumes (Vt) settings, ventilation modes and predefined age groups in invasively ventilated children.

Method: In this prospective observational physiology study, consecutive mechanically ventilated children from 1 month to 18 years of age were enrolled between August 2024 and May 2025 in a National Board of Exams-affiliated 30-bedded pediatric ICU. The data were collected within 24-hours of intubation, as soon as the patient was stable for data collection. Fifteen minutes before measurement, subjects were suctioned and circuit was cleared of water to prevent auto-triggering. Ventilator parameters were measured under static conditions. Flow and pressure values were obtained from the Mindray SV 600 ventilator, measured using differential pressure flow sensors and pressure sensors on the inspiratory and expiratory sides. Subjects were well sedated; If necessary, they were paralysed to ensure no spontaneous breathing during measurements. First the data was collected in Volume-Control Continuous mandatory ventilation (VC-CMV) at 6ml/kg Vt and then Vt increased to 8ml/kg and ventilated for 5 to 6 minutes to allow stabilisation and then data at 8ml/kg Vt was collected. After this, mode was changed to Pressure-control continuous mandatory ventilation (PC-CMV) mode and maintaining same Positive End Expiratory Pressure (PEEP) and Respiratory Rate (RR) and adjusting inspiratory time to accomodate the inspiratory flow and Peak Inspiratory Pressure (PIP)  was set to deliver 6ml/kg Vt. After 5 to 6 minutes of ventilation at this setting, data was collected. Now thw PIP was increased to deliver 8ml/kg Vt and after ventilating for 5 to 6 minutes at this Vt, data was now collected. In both PC-CMV and VC-CMV modes, inspiratory and expiratory holds were applied at each step to measure Pplat and PEEP, respectively. MPauto, calculated in real time by the Mindray SV-600 ventilator, was compared with equation-derived MP (MPcalc) using comprehensive and surrogate equations during continuous mandatory volume-control (VC-CMV) and pressure-control (PC-CMV) ventilation at Vt of 6 and 8 mL/kg body weight. Subgroup analyses considered age and pediatric ARDS (PARDS). In VC-CMV mode, MP was calculated with Gattinoni equation (MPVCcomprehensive) and Giosa surrogate equation (MPVCsurrogate). In PC-CMV mode, Van der Meijden comprehensive equation (MPPCcomprehensive) and Becher surrogate equation (MPPCsurrogate) were used. Bland-Altman analyses were used to evaluate the level of agreement.

Results: We included 147 children with median(IQR) age of 49 (16-92) months, of whom 34 had PARDS. MPauto showed strong agreement with MPcalc across ventilation modes and Vts settings. The agreement was highest in VC-CMV, with minimal bias (-0.12 to +0.011 Joules/min; ICC>/=0.95) and more than 88% of observations within CLoA. In PC-CMV, MPauto demonstrated systematic negative bias relative to MPcalc (Bias -1.23 to -0.62 Joules/min, ICC >/=0.92). These observations were also made among subjects with PARDS. Age affected the level of agreement between MPauto and MPcalc (slope: -0.008 to -0.005), particularly in PC-CMV mode (R2 = 0.226 to 0.27), where PARDS status modified this relationship only in PC-CMV mode (P<0.05)

Conclusion: MPauto by Mindray SV-600 demonstrated strong agreement with equation-derived MP during Volume-controlled ventilation across different age groups. However, MPauto showed a negative bias relative to equation-derived MP in pressure-controlled mode, particularly among younger children and those with PARDS