Evaluation of the role of mechanical power normalised for static compliance in predicting weaning outcome of patients receiving invasive mechanical ventilation for acute respiratory distress syndrome.

Patients satisfying clinical criteria for ARDS according to Berlin definition will be included. At baseline, patients will be  maintained deeply sedated and paralysed, ventilated in volume control with a square wave form without any inspiratory pause, applying a tidal volume between 4-6 mL/kg of ideal body weight with a PEEP value and FiO2  set by the attending physician to ensure an arterial saturation between 93 and 97%. At baseline, data will be  collected including age, sex, body mass index, Simplified Acute Physiology Score (SAPS II), cause for ARDS, PaO2/FiO2, PaCO2, and clinical mechanical ventilator setting (PEEP, respiratory rate, tidal volume). ARDS patients will be classified as mild (200 mmHg < PaO2/FiO2 ratio ≤ 300 mmHg), moderate (100 mmHg < PaO2/FiO2 ratio ≤ 200 mmHg), or severe (PaO2/FiO2 ratio ≤ 100 mmHg) according to the Berlin definition . Once the patients clinical condition improves is considered ready to wean ,under deep sedation the variables determining the mechanical power and plateau pressure will be  recorded. There after the sedation is stopped and gradual reduction in the mechanical ventilation support is done . Once patient fulfils the criteria for weaning  will be given SBT with CPAP of 5 cm of H20 And PS of 5cm of H2O Number of incidents of weaning failure will be recorded and correlated with the Mechanical power corrected to static compliance  Those who show intolerance to SBT or do not fulfil weaning protocol will be reinitiated on sedation, and reconsidered at 24 hrs interval by same methodology.