Neostat Vs. Pedicap
Title: The Impact of Colorimetric ETCO2 Devices on Airway Resistance
Background: Colorimetric CO2 devices utilize a pH sensitive chemical indicator, through a display of color change, which indicates the presence of end-tidal CO2 (ETCO2). Our group has previously demonstrated ETCO2 can identify airway obstruction during newborn resuscitation. However, the effect on airway resistance is unknown.
Objective: To determine the degree of inspiratory airway resistance (Rinsp) caused by two commonly used colorimetric ETCO2devices.
Design/Methods: We tested Pedi-Cap (Covidien, Mansfield, Ma) and Neo-StatCO2 (Mercury Medical, Clearwater, Fla.) using a neonatal test lung. We evaluated the Rinsp at baseline and with each device at pressure settings of 25, 30, 40 cm H20 and rates of 40, 60, 80, 100 bpm, as well as the resistance of each device in an open circuit. The pressure change over each ETCO2 device was measured by a distal side stream manometer. In addition the individual resistance of neonatal endotracheal tubes were measured.
Results: The imposed resistance of both of the ETCO2 devices was significantly higher than baseline (see figure). The imposed resistance of the Neo-StatCO2 was significantly larger than the Pedi-Cap (see figure).
Conclusions: While there appears to be no drop in delivered pressure, ETCO2 devices increases the resistance of airflow into the lungs. Individual types of ETCO2 devices have significantly different inspiratory resistance. The effect of increased expiratory resistance particularly in spontaneously breathing non-intubated neonates needs prospective evaluation to determine the effects on work of breathing.
The rate of ventilation had no effect on resistance and there was no pressure drop across either ETCO2 device. The resistance of the NeoStat (105 cm H2O/L/s) was between that of a 2.5 (90 cm H2O/L/s) and a 2.0mm ETT (127 cm H2O/L/s) at 8 LMP with no resistance on the distal end.