2002 OPEN FORUM Abstracts
NEW CLOSED SUCTION CATHETER DESIGN REDUCES VENTILATOR VOLUME LOSS DURING SIMULATED SUCTION EVENTS
Theron Van Hooser M Ed RRT, Ed Madsen, Tom Flood, Research and Development Department, Ballard Medical Products, Draper Utah
Background: One advantage of using a closed suction catheter system for suction is that the patient does not need to be disconnected from the ventilator breathing circuit (VBC). All closed suction systems should be rinsed following the suction procedure. During the rinse procedure, some ventilator tidal volume is lost (removed), because the catheter tip is still within the VBC. Furthermore, accidental activation of suction may occur because of patient position or inadvertent manipulation. In order to alleviate this situation, a new design was chosen (Ballard TRACH CARE-72*, REF 227) with a separate and integrated cleaning chamber. When the catheter is fully withdrawn, a flapper valve closes over the catheter, within the cleaning chamber. This valve restricts the amount of volume removed from the VBC and causes saline to be drawn from the attached vial. This effectively limits the amount of volume removed from the VBC, and makes the rinse procedure essentially ?one handed?. The aim of this study was to measure, document, and compare the amount of tidal volume loss during rinse or accidental thumb valve activation.
Methods: 26 samples each of the original design REF 2210, and the new design REF 227 were selected at random. A Nellcor, Puritan-Bennett 840 adult mechanical ventilator (Mallinckrodt Inc, Carlsbad CA) in volume control mode was set as follows; tidal volume 800 ml, rate 20 bpm, PEEP 5 cm/H20 trigger sensitivity -20 cm/ H20. Negative 20 trigger sensitivity was chosen to avoid auto trigger of the ventilator. The VBC was attached to a calibrated Michigan Test Lung (Michigan Instruments, Grand Rapids Mi.), with the resistance and compliance set for a ?normal? adult. The samples were placed into the circuit in the normal configuration. The samples were attached to an electrically powered, vacuum source (MobileVac III, Aeros Inst. Gurnee Ill.) set at -120 mm/Hg. Each sample was connected in the normal fashion. The thumb valve was depressed for 30 sec to simulate accidental activation. The catheters were rinsed with 15 ml of saline (Ballard REF 116). Mean tidal volumes delivered into the test lung through the VBC were recorded; before suction, after suction, before rinsing and after rinsing.
Results: Pre-suction and pre-rinse procedures both systems delivered the same tidal volumes. There was essentially no difference between the REF 2210 design and REF 227 design. After suction, there was a large difference of 527.5 ml, and 627.9 ml after rinse. The REF 2210 design essentially removed all tidal volume during the rinse procedures.
Discussion: Because the tidal volume is drawn into the catheter rather than delivered to the VBC, it is considered ?lost?. It should be noted that this is not a realistic clinical situation and that actual tidal volume loss during simulated suction was not measured.12 seconds is the recommended maximum time suction should be applied during the actual suction event. We used 30 seconds which was excessive and aggressive for normal clinical airway suction, but probably common for accidental activation. It should also be noted that since the ventilator was set on volume control and negative 20 sensitivity, the ventilator did not trigger did not deliver additional flow. With the ventilator set to deliver only 800 ml, the REF 227 delivered 527.5ml and 627.9ml. REF 2210 delivered none, a clear and dramatic difference. With REF 227, some volume was lost, but over half of the desired 800 was delivered into the test lung during the rinse procedure. This test was designed to document the difference in performance of the two designs, and is not representative of an actual clinical situation.
Conclusion: The new design, REF 227 (TRACH CARE-72*) dramatically reduces ventilator volume loss as compared to the original REF 2210 design during the rinse event or during accidental thumb valve activation.