The Science Journal of the American Association for Respiratory Care

2006 OPEN FORUM Abstracts

Bench Examination of Pressure Distal to the Endotracheal Tube (ETT) While Suctioning the Neonate. 

John S Emberger BS RRT, Joel Brown II BS RRT, Robert Locke DO, John Stefano MD, Departments of Respiratory Care and Neonatology, Christiana Care Health System, Newark DE.

Background: Both closed and open suctioning are used in neonates. We examined the pressure waveform on the distal (patient) side of the ETT for an "actively breathing" neonatal bench model during suctioning.

Methods: A neonate lung model was created simulating spontaneous breaths. The lung was enclosed in a container (Comp.=0.0018 L/cmH2O, Resist.=65 cmH2O/L/sec, Time Constant=0.117). Intermittent regulated vacuum was applied to the container, creating reproducible inspirations. A spirometer (CO2SMOPlus, Respironics) was placed distal to both the ETT and suction catheter position to capture the pressure wave during suctioning. Vent settings: PIP=20 cmH2O, PEEP=5 cmH2O, Rate=26, I-time=0.4 sec. A 3.0 ETT and #6 fr. suction catheters were used. Four scenarios were examined:  1) Open Suctioning  2) Closed suctioning on Time Cycled Pressure Limited (TCPL) ventilation (VIP, Bird Medical Systems)   3) Closed suctioning on Pressure Controlled (PCV) ventilation (Evita 4, Draeger Medical)  4) Closed suctioning on Volume Targeted Pressure Limited (VTPL) ventilation (Evita 4, Draeger Medical)

Results: Pressures measured in the bench model distal to the ETT are displayed:

  Open Suctioning Closed TCPL Closed PCV Closed VTPL
Avg Pressure - 6.0 cmH2O 1.7 cmH2O 1.2 cmH2O 2.5 cmH2O
Min Pressure -23.9 cmH2O -18.1 cmH2O -17.2 cmH2O -14 cmH2O
Max Pressure 6.2 cmH2O 16.2 cmH2O 18.7 cmH2O 24.2 cmH2O

Conclusion: Caregivers expect pressure on the distal side of the ETT during open suctioning to be lower than when closed suctioning is used. Our study shows that with standard suction pressure and standard suction catheters, pressures distal to the ETT can approach -25 cmH2O, and can average -6.0 during an open suctioning event. We also found that average pressure distal to the ETT is not well preserved even when performing closed suctioning with TCPL and PCV.  In this neonatal bench model, the VTPL preserved the distal airway pressure most effectively, yet distal pressure still dropped as low as -14 cmH20 during a closed suctioning event.

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