2001 OPEN FORUM Abstracts
RESISTANCE CHARACTERISTICS OF ULTRATHIN-WALLED AND CONVENTIONAL ENDOTRACHEAL TUBES FOR NEONATES
Paul N. Austin, CRNA, PhD (LtColUSAF NC)1; Scott Moschel, RN, BSN2; Christopher Ehrler,RN, BSN2; Robert S. Campbell, RRT, FAARC2; Richard D.Branson, RRT, FAARC2; 1Uniformed Services University ofthe Health Sciences, 2University of Cincinnati
Background: Kolobow introducedthe concept of an ultrathin-walled endotracheal tube (UT-ETT) in 1994. (BiomedInstrument Technol 1994;28:123). Commercially available UT-ETT have recentlybecome available (T-Wall, Vital Signs, Totowa, NJ). We evaluated the resistancecharacteristics of conventional ETT and new UT-ETT in the laboratory.
Methods: The resistance ofthree samples of each ETT (conventional ETTs: 3 mm ID, 4.3 mm OD; 3.5 mm ID,4.9 mm OD; and 4 mm ID, 5.6 mm OD and UT-ETT 3.6 mm ID, 4.3 mm OD) were measuredusing a RT-200 analyzer (Allied Products, St Louis, MO). The ETTs were cut tothe same length 13 cm that included the connector. Each ETT was position inthe same curvature using a clay template. Inspiratory resistance was measuredat flow rates of 3, 3.25, 3.5, 3.75, 4, 5, 6, 7, 8, 9, 10, and 20 L/min. Inthe second part of the evaluation the ETTs were attached to a test lung (MichiganInstruments, Grand Rapids, MI) with C 0.01 L/cm H2O, R 50 H2O /L/s.Spontaneous breathing was simulated with a tidal volume of 12 ml and peak inspiratoryflow of 2 L/min. Flow, volume, and pressure was measured at a point betweenthe ETT and the test lung using a CO2SMO Plus respiratory monitor (NovametrixMedical Systems, Wallingford, CT) at a rate of 100x/s. Data was saved to thehard drive of a personal computer then exported to an Excel (Microsoft, Redmond,WA) spreadsheet for further analysis. Pressure volume curves were constructedallowing for qualitative evaluation of imposed inspiratory work.
Results: For the same OD,the UT-ETT results in lower resistance and lower work of breathing. Comparedto the 3.0 ID ETT the UT-ETT produced 54-56% less resistance at flows of 1-10L/min. Conclusions: The new UT-ETT provides lower resistance and reduced workof breathing at the same OD (same risk of tracheal damage). Future clinicaltrials should evaluate any impact.