Wenzel Christin, Schumann Stefan, Spaeth Johannes
Department of Anesthesiology and Critical Care, Medical Center, University of Freiburg, Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany.
Respir Care. 2017 Sep;62(9):1171-1177. doi: 10.4187/respcare.05426. Epub 2017 Aug 14.
Tubing systems are an essential component of the ventilation circuit, connecting the ventilator to the patient's airways. Coaxial tubing systems incorporate the inspiratory tube within the lumen of the expiratory one. We hypothesized that by design, these tubing systems increase resistance to air flow compared with conventional ones.
We investigated the flow-dependent pressure gradient across coaxial, conventional disposable, and conventional reusable tubing systems from 3 different manufacturers. Additionally, the additional work of breathing and perception of resistance during breathing through the different devices were determined in 18 healthy volunteers.
The pressure gradient across coaxial tubing systems was up to 6 times higher compared with conventional ones (1.90 ± 0.03 cm HO vs 0.34 ± 0.01 cm HO, < .001) and was higher during expiration compared with inspiration ( < .001). Additional work of breathing and perceived breathing resistance were highest in coaxial tubing systems, accordingly.
Our findings suggest that the use of coaxial tubing systems should be carefully considered with respect to their increased resistance.
