Table 2. Measurements of trachea by US and procedural data.

Variables			Bronchoscopy-guided PDT (n=29)			US-guided PDT (n=25)							Total PDT (n=54)
	n	%	Mean+SD	Median	25th-75th percentiles	n	%	Mean+SD	Median	25th-75th percentiles	n	%	Mean+SD	Median	25th-75th percentiles	p
Number of tracheal punctures				2	1-2				1	1-2				1	1-2	0.678
Skin-trachea distance (mm)			N/A					9.2+1.9					N/A
Tracheal diameter (mm)			N/A					21.3+2.4					N/A
Change in the puncture site after US			N/A			5	20						N/A
Size of tracheostomy tube (mm)				7.5	7-8				7.5	7-8				7.5	7-8	0.664
Duration of procedure (mm)				10	7-15				13	8-17				11	7-17	0.387
US: Ultrasound; PDT: Percutaneous dilatational tracheostomy; N/A: Not applicable; SD: Standard deviation.