Gopinathannair Harikumar1, Anne Greenough, Gerrard F Rafferty. 1. King's College London, MRC-Asthma Centre, Division of Asthma, Allergy and Lung Biology, Kings' College London School of Medicine at Guy's, King's College and St Thomas' Hospitals, London, UK.
Abstract
UNLABELLED: Many modern "paediatric" mechanical ventilators have in-built features for estimation of respiratory mechanics which could be useful in the management of ventilated infants and children. The aim of this study was to determine if such measurements were reproducible and accurate. Ventilator (Draeger Evita 4) displayed compliance (Cvent) and resistance (Rvent) values were assessed and compared to the results of respiratory system mechanics (respiratory system compliance (Crs) and resistance (Rrs)) measurements obtained using a single breath occlusion technique. Seventeen children (median age 5.1; range 0.3 to 16 yrs) were studied on 24 occasions. The mean coefficients of variations for the techniques were similar (Cvent 13%; Crs 11%; Rvent 16%; Rrs 14%). The mean (SD) Crs (22.8 (12.3) ml/cmH2O) did not differ significantly from Cvent (22.1 (12.7) ml/cm H2O) but the mean Rrs 21.0 (12.7) cmH2O/l/s was significantly higher than the mean Rvent 32.0 (32.0) cmH2O/l/s (p = 0.03). Bland and Altman analysis demonstrated a mean difference of -10.94 cmH2O/l/s (SD 24.1) between Rrs and Rvent; the agreement between Rrs and Rvent decreased as Rrs increased (p = 0.008). CONCLUSIONS: Ventilator assessment of compliance, but not resistance, using the Evita 4 is reproducible and reliable.
UNLABELLED: Many modern "paediatric" mechanical ventilators have in-built features for estimation of respiratory mechanics which could be useful in the management of ventilated infants and children. The aim of this study was to determine if such measurements were reproducible and accurate. Ventilator (Draeger Evita 4) displayed compliance (Cvent) and resistance (Rvent) values were assessed and compared to the results of respiratory system mechanics (respiratory system compliance (Crs) and resistance (Rrs)) measurements obtained using a single breath occlusion technique. Seventeen children (median age 5.1; range 0.3 to 16 yrs) were studied on 24 occasions. The mean coefficients of variations for the techniques were similar (Cvent 13%; Crs 11%; Rvent 16%; Rrs 14%). The mean (SD) Crs (22.8 (12.3) ml/cmH2O) did not differ significantly from Cvent (22.1 (12.7) ml/cm H2O) but the mean Rrs 21.0 (12.7) cmH2O/l/s was significantly higher than the mean Rvent 32.0 (32.0) cmH2O/l/s (p = 0.03). Bland and Altman analysis demonstrated a mean difference of -10.94 cmH2O/l/s (SD 24.1) between Rrs and Rvent; the agreement between Rrs and Rvent decreased as Rrs increased (p = 0.008). CONCLUSIONS: Ventilator assessment of compliance, but not resistance, using the Evita 4 is reproducible and reliable.