Use of siliconised infant endotracheal tubes reduces work of breathing under turbulent flow

When 2.5 and 3.0 mm ID ETTs were examined, laminar flow (Re <2300) across the tube was observed, and there were no clinically significant differences in the ventilation parameters between non-siliconised and siliconised tubes. Whereas, when 4 mm ID ETTs were tested, turbulent flow was observed, and PIP, Rins, Rexp and WOBvt were significantly lower (5%, 17%, 17%, and 7%, respectively) (P < 0.05), but PIF and PEF were significantly higher (8%, 14%) (P < 0.05). Thus, the silicone inner surface of ETT offers less resistance and WOBvt in presence of turbulent flow. However, artifacts observed on the surface of non-siliconised and siliconised ETTs can potentially impair ventilation.