Comparison of four knots for securing endotracheal tubes in an experimental model

To compare the retention strength of four endotracheal tube (ETT) fixation techniques and determine whether modified knot configurations provide superior resistance to slippage and displacement compared with conventional knot configurations.

Experimental laboratory study.

None.

ETTs with internal diameters (IDs) of 3.0 mm, 6.5 mm, 10 mm, and 14 mm were secured using four fixation techniques: single knot (SK), double surgeon's loop (DL), clove hitch (CH), and modified cow hitch (MC). A single polyvinyl chloride tie (length 650 mm, width 1.6 mm) was used as the standardized securing material. Fixation strength was evaluated using a universal testing machine. Each combination of fixation technique and ETT size was tested 10 times. The tension at the onset of slippage (slip) and the maximum tension before failure were recorded. Data were analyzed using Kruskal-Wallis tests with Bonferroni correction.

The CH technique had the highest slip tension across all tube diameters (all p < 0.0001), whereas the DL technique consistently showed the lowest values (e.g. ID3.0: SK versus DL, p = 0.021; ID10: SK versus DL, p = 0.011). For larger tube sizes (10 mm and 14 mm), the maximum tension before failure was significantly greater for the CH and MC techniques than for the SK and DL techniques (all p < 0.0001). For smaller tubes (3.0 mm and 6.5 mm), the CH technique showed a significantly higher maximum tension than all other techniques (all p < 0.0001). Early detachment of the SK component contributed to reduced slippage resistance in the MC method.

The CH and MC techniques provided superior fixation strength compared with the SK and DL techniques, with the CH showing the greatest resistance to slippage.

These findings suggest that modified knot configurations may reduce the risk of unintended ETT displacement in clinical practice.