Tidal volume measurement error in pressure control modes of mechanical ventilation: A model study. (1st August 2016)

• Record Type: Journal Article
• Authors: Chatburn, Robert L.; Mireles-Cabodevila, Eduardo; Sasidhar, Madhu
• Is Part Of: Computers in biology and medicine. Volume 75(2016)
• Page Start: 235
• Page End: 242
• Publication Date: 2016-08-01
• Subjects: Mechanical ventilation -- Pressure control -- Accuracy -- Taxonomy -- Tidal volume -- Error -- Simulation -- Model; Medicine -- Data processing -- Periodicals; Biology -- Data processing -- Periodicals; 610.285
• DOI: 10.1016/j.compbiomed.2016.06.011
• Languages: English
• ISSNs: 0010-4825

Abstract

Abstract: Tidal volume ( V T ) measurement during pressure control (PC) ventilation with preset inspiratory time may produce errors due to patient inspiratory effort. We evaluated V T error in 3 common ICU ventilators. Methods: Simulated patient: 60 kg adult with ARDS using IngMar Medical ASL 5000 having moderate inspiratory effort. Ventilators evaluated: Covidien PB 840, Maquet Servo-i, and Dräger Evita XL, PC breaths at preset inspiratory time ( T I ) 0.6–1.4 s. V T error was defined as ventilator displayed V T minus the simulator displayed V T (mL/kg or % of true). Results: Relaxation of inspiratory effort caused flow reversal (exhalation) during T I, which led to V T error. For the PB 840, V T error was proportional to T I (maximum −2.0 mL/kg, −19%). For the Servo-i, V T error was not related to T I (maximum error −0.2 mL/kg or −1.2%). Volume error for Evita XL was not related to T I (maximum error was −0.7 mL/kg or −6%). Conclusions: Calculation of V T as the integral of flow over the preset inspiratory time rather than the period between zero crossings of flow may result in underestimation of both inhaled and exhaled volumes. The size of V T error can be large enough to potentially affect patient outcomes on some ventilators. Highlights: Some pressure control modes allow exhalation during the preset inspiratory time. Exhalation during the inspiratory period can lead to error calculating tidal volume. Tidal volume calculation error can be large enough to affect patient outcomes.