2006 OPEN FORUM Abstracts
Bench Study Examination of the Pressure Waveform Distal to the Endotracheal Tube (ETT) While Suction Catheter is Advanced into THE ETT.
John S Emberger BS RRT, Joel Brown II BS RRT,
Background: Closed and open suctioning are
routinely used for neonates. We examined pressure waveforms on the distal
(patient) side of the ETT of an "actively breathing" neonate model while a
suction catheter is in the ETT, but no suction applied.
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 distal to the ETT. 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 with the suction catheter in the ETT but with no suction
applied: 1) Open Suctioning 2) Closed suction - Time Cycled Pressure
Limited (TCPL) ventilation (VIP, Bird Medical Systems) 3) Closed suctioning - Pressure Controlled
(PCV) ventilation (Evita 4, Draeger Medical)
4) Closed suctioning - Volume Targeted Pressure Limited (VTPL)
ventilation (Evita 4, Draeger Medical)
Results:
With the suction catheter in the ETT but no suction applied, open suctioning showed
negative pressure inflections with each patient inspiratory effort. Closed
suction mechanical breaths showed pressure spikes of
Conclusion: While
the suction catheter is in the ETT, but with no suction applied, "actively
breathing" neonates may experience short-lived pressure spikes at the start of
exhalation due to passive lung recoil against expiratory resistance from the
catheter. This model is passive exhalation and live neonates may even actively
exhale against the expiratory resistance of the catheter creating higher
pressure spikes.