Table 3.

Safety device usage over time.

Year surveyed	1989 (%)	1994 (%)	1999 (%)	2004 (%)	2011 (%)	2016 (%)
Level sensor	65	67	79	90	100	99
Bubble sensor	72	85	88	83	96	100
One-way valve (vent)	52	66	69	75	87	89
One-way valve (purge)	72	90	92	92	85	70
Oxygenator gas supply analyzer	28	49	47	48	40	40
Arterial blood gases	67	86	71	77	83	90
Arterial blood O2 saturation	9	26	26	19		37
Venous blood gases	48	52	31	21	25	17
Venous blood O2 saturation	48	78	88	94	90	96

North America trends of safety devices and circuit continuous monitoring use (% use).