Table 1.
Patient Characteristics at the Time of Extracorporeal Membrane Oxygenation Referral and Clinical Outcomes
| Characteristic | Overall (N = 90) | Capacity for ECMO (n = 35) | No Capacity for ECMO (n = 55) | P Value |
|---|---|---|---|---|
| Age, yr | 40.0 (34.0–48.0) | 40.0 (32.0–47.0) | 41.0 (35.0–51.0) | 0.07 |
| Sex, F | 25 (27.8) | 10 (28.6) | 15 (27.8) | 0.89 |
| Body mass index, kg/m2 | 35.0 (30.0–39.0) | 35.0 (31.0–40.0) | 34.0 (32.0–38.0) | 0.40 |
| Comorbidities | ||||
| Hypertension | 22 (24.4) | 10 (28.6) | 12 (21.8) | 0.47 |
| Diabetes mellitus | 16 (17.8) | 4 (11.4) | 12 (22.2) | 0.27 |
| Hyperlipidemia | 3 (3.3) | 0 (0.0) | 3 (5.5) | 0.28 |
| Asthma | 5 (5.6) | 5 (14.3) | 0 (0.0) | 0.004 |
| Obstructive sleep apnea | 3 (3.3) | 2 (5.7) | 1 (1.8) | 0.32 |
| Hypothyroidism | 3 (3.3) | 2 (5.7) | 1 (1.8) | 0.32 |
| Other* | 8 (8.9) | 6 (17.1) | 6 (10.9) | 0.53 |
| Pregnant or postpartum | 4 (4.4) | 2 (5.7) | 2 (3.6) | 0.64 |
| Vasopressors | 37 (41.1) | 11 (31.4) | 26 (47.3) | 0.14 |
| Acute kidney injury | 24 (26.7) | 9 (25.7) | 15 (27.3) | 0.87 |
| Renal replacement therapy | 7 (8.1) | 3 (8.6) | 4 (7.8) | >0.99 |
| Duration of mechanical ventilation, d | 2.0 (1.0–3.0) | 1.0 (1.0–3.0) | 2.0 (1.0–5.0) | 0.03 |
| Ventilator settings | ||||
| Mode | 0.63 | |||
| Volume control | 74 (92.5) | 30 (91.9) | 44 (93.6) | — |
| Pressure control | 5 (6.3) | 2 (6.1) | 3 (6.4) | — |
| Airway pressure release ventilation | 1 (1.3) | 1 (3.0) | 0 (0.0) | — |
| Respiratory rate | 28.0 (24.0–32.0) | 30.0 (26.0–32.0) | 28.0 (22.0–32.0) | 0.29 |
| Vt, ml | 410.0 (360.0–450.0) | 400.0 (350.0–450.0) | 430.0 (385.0–460.0) | 0.20 |
| Plateau pressure, cm H2O | 33.0 (28.0–38.0) | 34.5 (32.0–38.0) | 29.0 (22.0–36.5) | 0.08 |
| FiO2 | 1.0 (1.0–1.0) | 1.0 (1.0–1.0) | 1.0 (1.0–1.0) | 0.13 |
| Positive end-expiratory pressure, cm H2O | 14.0 (12.0–16.0) | 15.5 (12.0–18.0) | 14.0 (12.0–15.0) | 0.07 |
| Arterial blood gas | ||||
| pH | 7.31 (7.24–7.38) | 7.30 (7.23–7.35) | 7.31 (7.24–7.38) | 0.62 |
| Partial pressure of carbon dioxide, mm Hg | 57.5 (46.0–68.5) | 57.0 (45.0–66.0) | 60.0 (47.0–69.0) | 0.69 |
| Partial pressure of oxygen, mm Hg | 63.0 (54.0–72.0) | 64.0 (57.0–72.0) | 62.0 (53.0–70.0) | 0.35 |
| Adjunctive therapies | ||||
| Neuromuscular blocking agent | 81 (96.4) | 34 (97.1) | 47 (95.9) | >0.99 |
| Prone positioning | 46 (55.4) | 20 (58.8) | 26 (53.1) | 0.60 |
| Inhaled pulmonary vasodilators | 12 (14.3) | 8 (22.9) | 4 (8.2) | 0.11 |
| Miles from referring to receiving hospital | 165.0 (100.0–243.0) | 163.0 (81.0–211.0) | 171.0 (105.0–278.0) | 0.28 |
| Outcome | ||||
| Died before hospital discharge† | 64 (71.1) | 15 (42.9) | 49 (89.1) | <0.001 |
| Survived to hospital discharge‡ | 23 (25.6) | 18 (51.4) | 5 (9.1) | <0.001 |
| Remains alive in the hospital§ | 3 (3.3) | 2 (5.7) | 1 (1.8) | 0.07 |
Definition of abbreviations: ECMO = extracorporeal membrane oxygenation; IQR = interquartile range.
Data are expressed as median (IQR) or frequency (percentage) unless otherwise indicated. The Wilcoxon rank-sum test, Fisher’s exact test, or the Kruskal-Wallis test was used to examine differences between groups when appropriate. Missingness in observations: mode (n = 10), body mass index (n = 7), ventilator days (n = 2), receipt of renal replacement therapy (n = 4), ventilator mode (n = 10), respiratory rate (n = 19), Vt (n = 18), positive end-expiratory pressure (n = 10), pH (n = 6), PaCO2 (n = 8), PaO2 (n = 4), receipt of prone positioning (n = 7), receipt of neuromuscular blocking agent (n = 6), and receipt of inhaled pulmonary vasodilator (n = 6).
Other comorbidities included (n = 1 for each) Asperger syndrome, polycystic ovarian syndrome, and thyroid cancer status after thyroidectomy in the capacity for ECMO group and chronic atrial fibrillation, congestive heart failure, osteoporosis, seizures, and sickle cell disease in the no capacity for ECMO group.
Median time from referral for ECMO to death was 19.0 days (IQR, 7.0–47.0) among patients for whom the capacity to provide ECMO was available and 7.0 days (IQR, 4.0–12.0) among patients for whom capacity to provide ECMO was unavailable.
Median time from referral for ECMO to discharge from the hospital alive was 36.0 days (IQR, 0.0–72.0) among patients for whom the capacity to provide ECMO was available and 32.0 days (IQR, 28.0–43.0) among patients for whom capacity to provide ECMO was unavailable.
Median time from referral for ECMO to last follow-up among patients who remained alive in the hospital was 40.0 days (IQR, 30.0–55.0) among patients for whom the capacity to provide ECMO was available and 50.0 days (IQR, 50.0–50.0) among patients for whom capacity to provide ECMO was unavailable.