Poorly placed tracheostomy tubes: Effects on flow and resistance.

This study aimed to investigate the effects of an incorrectly positioned tracheostomy tube on flow resistance. A laboratory-based model of the trachea was used with both cuffed and uncuffed tracheostomy tubes inserted to variable depths. With a constant metered flow through the model, the pressure for given depths of insertion was recorded. The model was then re-run to test the effect of different flow rates on the system. A total of 468 individual results were grouped and statistically analysed. They showed that both over- and under-insertion increase the pressure within the circuit and that a cuffed tracheostomy tube offers a degree of protection against this. These results were statistically significant with P < 0.05 demonstrating that incorrect positioning has a greater resistance to flow. These results provide an essential scientific basis for further work to assess the clinical significance of incorrect positioning as well as suggesting the need to monitor tube position.