Table 1.

Patient Characteristics Prior to ECMO Support by Age Group and Annual ECMO Volume Category, 1989–2013

	Neonatal (n = 30,909, N = 197)				Pediatric (n = 14,725, N = 235)				Adult (n = 10,588, N = 214)
Annual Hospital ECMO Volume Categories	1–5	6–14	15–30	>30	1–5	6–14	15–30	>30	1–5	6–14	15–30	>30
Number of patients	2,718	10,726	12,770	4,695	3,477	5,956	4,709	583	1,243	1,790	2,800	4,755
Type of ECMO support, %
Respiratory	74	77	80	87	48	39	39	39	57	54	51	44
Cardiac	23	20	17	11	46	49	41	34	33	39	39	41
ECPR	3	3	4	2	7	12	20	26	10	7	10	16
Pre-ECMO characteristics, %
Female	43	42	41	42	48	48	47	46	42	38	37	35
Acute renal failure	1	1	1	1	2	2	2	2	4	6	4	4
Comorbid condition*	4	3	3	2	10	10	12	15	18	18	17	12
Pre-ECMO characteristics, median
Age, d	2	2	1	1
Age, yr					0	1	1	1	35	48	49	51
pH†	7.28	7.29	7.32	7.38	7.30	7.28	7.27	7.24	7.25	7.25	7.26	7.29
PF ratio†	38	39	39	39	57	60	63	63	61	63	63	75
Pre-ECMO hours of mechanical ventilation	26	26	24	22	34	24	24	25	23	22	20	17

Definition of abbreviations: ECMO = extracorporeal membrane oxygenation; ECPR = ECMO during cardiopulmonary resuscitation; n = number of patients; N = number of centers; pH = arterial blood pH; PF ratio = the ratio of arterial partial pressure of oxygen to fraction of inspired oxygen; pre-ECMO hours of mechanical ventilation = the number hours of mechanical ventilation a patient received prior to ECMO cannulation.

^*Comorbid conditions were defined as present or absent using definitions described in the literature for neonates (46), pediatrics (47), and adults (48).

^†Most abnormal value recorded within 6 h of receipt of ECMO support.