The Science Journal of the American Association for Respiratory Care

2006 OPEN FORUM Abstracts

OPEN VERSUS CLOSED SUCTION DELIVERY DURING HIGH FREQUENCY OSCILLATORY VENTILATION (HFOV)

Dennis Gaudet, RRT; Matthew P. Branconnier, RRT, EMT; Dean R. Hess, PhD, RRT, FAARC. Massachusetts General Hospital and Harvard Medical School, Boston MA.

Background: Because the use of closed suction is not universally accepted during HFOV, it is the practice of some clinicians to disconnect the patient from HFOV for open suctioning. Anecdotally, we have noted fewer adverse clinical effects when closed suction, compared with open suction, is used during HFOV. We conducted this bench study to evaluate simulated tracheal pressure with open and closed suction during HFOV.

Method: A calibrated Sensormedics 3100A with a flexible circuit was connected to a cuffless endotracheal tube (Mallincrodt), the distal end of which was attached to a pressure sensor and Michigan Instruments neonatal test lung in a leak-free manner. All combinations of the following variables were evaluated: endotracheal tubes with internal diameters of 2.5 and 3.5 mm; mean airway pressure of 15 and 25 cm H2O; amplitude of 20 and 30 cm H2O; frequency of 10 and 14 Hz. A Ballard 6 French inline suction catheter with a 45o angle was used. Simulated tracheal suction was performed with the oscillator attached to the endotracheal tube (closed suction) or disconnected from the endotracheal tube (open suction). Suction was applied at 80 mm Hg in a manner simulating the clinical procedure. Data acquisition software (Analysis Plus) was used to record pressure at 100 Hz from the distal endotracheal tube (Novametrix NICO). For each set of variables, mean tracheal pressure and pressure amplitude were measured at the distal endotracheal tube (simulated trachea). Three representative breaths were analyzed.

Results: There was a significant change in mean tracheal pressure (29 ± 9% decrease; P < 0.001) and amplitude (64 ± 5% decrease; P < 0.001) when closed suction was applied. The pressure at the simulated tracheal level was always positive with closed suction. With open suction, the pressure at the simulated tracheal level dropped quickly to atmospheric and was sub-atmospheric during the application of suction (see figure). Also note that the time of interrupted ventilation was less with closed suction.

Conclusions: In this model of suctioning during HFOV, positive tracheal pressure was maintained with closed suction, but not with open suction. This suggests that closed suction may be preferable to open suction during HFOV. Because mean tracheal pressure and amplitude decreased even with closed suction, suction duration of should be minimized. Further work is needed to clinically validate these results.




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