Reliability of Respiratory System Compliance Calculation During Assisted Mechanical Ventilation: A Retrospective Study

Objectives: To compare respiratory system compliance (Crs) calculation during controlled mechanical ventilation (MV) and, subsequently, during assisted MV. Design: This is a single-center, retrospective, observational study. Setting: This study was conducted on patients admitted to Neuro-ICU of Niguarda Hospital (tertiary referral hospital). Patients: We analyzed every patient greater than or equal to 18 years old having a Crs measurement in controlled and in assisted MV within 60 minutes. Plateau pressure (Pplat) was considered reliable if it was deemed visually stable for at least 2 seconds. Interventions: Inspiratory pause was incorporated to detect Pplat in controlled and assisted MV. Calculation of Crs and driving pressure were achieved. Measurements and main results: A total of 101 patients were studied. An acceptable agreement was found (Bland-Altman plot bias -3.9, level of agreement upper 21.6, lower -29.6). Crs in assisted MV was 64.1 (52.6-79.3) and in controlled MV it was 61.2 (50-71.2) mL/cm H2o (p = 0.006). No statistical difference was found in Crs (assisted vs controlled MV) when peak pressure was lower than Pplat nor when peak pressure was higher than Pplat. Conclusions: A Pplat visually stable for at least 2 seconds leads to reliable Crs calculation during assisted MV.