Accuracy of volume measurements in mechanically ventilated newborns: A comparative study of commercial devices

Objective. Ventilatory measurements in ventilated newborns are increasingly used to monitor and to optimize mechanical ventilation. The aim of this st udy was to compare the accuracy of volume measurements by different instrum ents using standardized laboratory conditions. Methods. The accuracy of dis played volume values of different commercial devices (Bicore CP-100, Ventra k 1500, Ventrak 1550, Babylog 8000, PEDS IV and SensorMedics 2600) was inve stigated using adjustable calibration syringes (volume range 2-60 mi, breat hing rates 30/min-60/min) and humidified (>95%), heated (35 degrees C) brea thing gas with adjustable FIO2 (0.21-1.0). The pneumotach and also the tube s were placed within an incubator (37 degrees C). Results. The relative vol ume error of all devices was in conformity with clinically allowed toleranc es (Bicore CP-100 6.4 +/- 0.5% (mean +/- SD), Ventrak 1500 3.6 +/- 4.2%,Ven trak 1550 6.5 +/- 2.7%, Babylog 8000 -5.5 +/- 1.5%, PEDS IV -4.0 +/- 1.4%, SensorMedics 2600 3.5 +/- 1.75%) for the measuring range studied (10 mi < V < 60 mi, rate 30-60/min, FIO2 = 0.21). Unacceptable errors were obtained f or volumes lower than 10 mi with Bicore CP-100 (-28.5 +/- 26%) and PEDS IV (-10.3 +/- 3.4%). Changes in FIO2 had an important influence on volume meas urements and only the SensorMedics 2600 and the PEDS IV corrected properly for FIO2 changes. Conclusion. Most of the currently available neonatal spir ometry devices allow sufficiently accurate volume measurements in the range of 10-60 mi and at frequencies between 30-60/min provided that an increase d FIO2 is taken into account.