Use of PARniv for Early Diagnosis of LVF in AECOPD

invasive mechanical ventilation session in the BIPAP Mode with a pressure support (PS) level of 5cmH2O, a positive end expiratory pressure (PEEP) level of 5 cmH2O and an inspiratory fraction of oxygen (FiO2) allowing a pulse saturation (SpO2) of at least 92% for a one minute and followed by an increase of the PS level to 30cmH2O.The plethysmographic PAR (PAR) was calculated based on the following formula: PARpleth= PP30 / PP5