The Science Journal of the American Association for Respiratory Care

2008 OPEN FORUM Abstracts

TIDAL VOLUME AND MINUTE VENTILATION ASSESSMENT RELIABILITY WITH THE PURITAN BENNETT 840 VENTILATOR AND NICO MONITOR IN TWO VENTILATION MODES: ASSIST/CONTROL (VOLUME) AND BILEVEL.

Gary E. Gradwell1, Paul Marik2, Enrique Machare-Delgado2, Rodrigo Cavallazzi2, Bridget M. Dutill2, Silvana Romeo2, Tiffany Pezzano1



Background: In Bilevel (APRV), release volumes are governed by mechanical and physiologic factors making TV and MV measurements unpredictable compared to volume ventilation. Therefore, we decided to assess the reliability of TV and MV measurements in A/C (volume) and APRV with two different methods simultaneously (Puritan Bennett 840 ventilator and NICO monitor).

Methods: Twelve consecutive patients with severe ARDS had their ventilation mode changed from A/C to APRV. We recorded TV and MV on A/C and three time intervals on APRV for a mean of 22 hours. We used the following formula to calculate percent error: [(NICO measure - Ventilator measure)/Ventilator measure]*100. We also calculated mean percent error and SD.

Results: We calculated the difference between TV at Time 0 (A/C) and TV on APRV at three data points. The percent error in APRV for the TV and MV between the NICO and Ventilator was calculated for the whole cohort (36 data points). The results are shown in the table below.

Conclusion: The absolute difference in TV on A/C vs. APRV when measured by the ventilator alone was not statistically different. There were significant relative (percent) measurement differences between the NICO monitor and the ventilator in the TV during APRV. The central dispersion of TV was wider than the MV in APRV because the NICO coupled exhaled spontaneous volumes to release volumes when they occurred successively. The MV is a more reliable parameter and trended downward with a decrease in Vd/Vt (data not shown).