Table 4.

Peak intratidal NO concentrations in the artificial trachea resulting from different modes and sites of NO administration

Delivery mode	Flow proportional	Continuous	Pulsed
	Injection site relative to y-piece
Target [NO]	Distant	Distant	Distant	Close
5 ppm	6.27 ± 1.22	8.1 ± 2.59	8.73 ± 3.41	17.83 ± 5.66
10 ppm	12.22 ± 2.58	14.81 ± 4.62	16.15 ± 5.64	29.4 ± 6.27
20 ppm	23 ± 3.69	31.02 ± 9.92	33.35 ± 13.45	73.11 ± 24.25
40 ppm	45.21 ± 7.1	59.57 ± 20	68.4 ± 30.14	147.73 ± 38.1

NO was administered via “flow proportional” or “continuous delivery” through injection into the breathing circuit at 20 cm after the mechanical ventilator (distant to y-piece), or via pulsed delivery with injection distant or close to (i.e. 10 cm proximal of) the y-piece, sampled from a mid-tracheal sampling site, and quantified with ozone-based chemiluminescence. For each NO target concentration, mechanical ventilation was performed with ultra-low (230 ml), low (450 ml) or traditional (750 ml) tidal volumes applied via both pressure (PCV) and volume-controlled ventilation (VCV) with I:E ratios of 1:1 and 1:1.9 (12 conditions). Peak intratidal NO concentrations in the trachea were determined over a period of 120 s (n = 30 respiratory cycles) per each individual ventilation condition (i.e. n = 360 per tabular cell representing 12 ventilation conditions). Means ± SD