Table 1.

Changes in ventilation and oxygenation with changes in gas mixture in 10 infants with bronchiolitis on mechanical ventilation

	Patient
Variable	1	2	3	4	5	6	7	8	9	10
Age (months)	9	1	1	6	4	7	2	1	4	2
RSV positive	No	No	Yes	No	Yes	No	Yes	Yes	Yes	Yes
Ventilator rate	20	22	18	15	28	18	15	30	20	25
(breaths/min)
IT (s)	1.0	0.8	0.8	0.8	1.0	1.0	1.0	1.0	1.0	0.8
I:E	1:2	1:2	1:3	1:4	1:1	1:2	1:3	1:1	1:2	1:2
PaCO2(mmHg)
50/50 Nitrogen/	45	53	44	40	47	53	65	28	35	40
oxygen
50/50 Heliox	43	53	41	38	46	52	62	28	39	36
60/40 Heliox	34	51	44	39	48	45	65	26	37	38
70/30 Heliox	35	53	44	37	45	41	69	26	34	36
PaO2/FiO2
50/50 Nitrogen/	183	251	246	193	174	351	395	485	167	225
oxygen
50/50 Heliox	190	284	182	200	232	366	364	450	188	212
60/40 Heliox	245	220	325	200	203	370	330	445	183	230
70/30 Heliox	237	290	303	233	190	313	240	360	213	207
PaO2/PAO2
50/50 Nitrogen/	0.30	0.42	0.39	0.31	0.28	0.26	0.35	0.58	0.68	0.74
oxygen
50/50 Heliox	0.30	0.47	0.29	0.31	0.37	0.30	0.33	0.60	0.62	0.69
60/40 Heliox	0.39	0.38	0.54	0.33	0.34	0.29	0.37	0.62	0.60	0.69
70/30 Heliox	0.40	0.54	0.54	0.40	0.34	0.36	0.35	0.54	0.50	0.57

I:E, ratio of ventilator inspiratory to expiratory times; IT, ventilator inspiratory time; RSV, respiratory syncytial virus.