Table 1.
Characteristics, decision and outcomes of COVID-19 patients referred for ECMO
| All referrals (n = 1383) | Included for matching (n = 933) | ‘Perceived futility’ (n = 430) | p-value | |
|---|---|---|---|---|
| Demographics | ||||
| Age | 53 [45, 60] | 51 [43, 58] | 58 [52, 63] | < 0.001 |
| Male sex | 941 (69) | 641 (68.7) | 300 (69.8) | 0.74 |
| Body mass index (kg/m2) | 31.01 [27.02, 35.46] | 31.35 [27.34, 35.64] | 29.88 [26.31, 34.64] | 0.002 |
| Clinical frailty scale | 2 [2, 2] | 2 [2, 2] | 2 [2, 2] | < 0.001 |
| Immunocompromised | 82 (6) | 40 (4.3) | 42 (9.8) | < 0.001 |
| Pre-referral admission characteristics | ||||
| Hospital duration prior to IMV (days) | 5 [2, 8] | 4.5 [2, 7.92] | 6.52 [3, 9.38] | < 0.001 |
| IMV durationa (days) | 3.15 [1, 6] | 3 [1, 6] | 4 [2, 9] | < 0.001 |
| Cardiac arrest | 43 (3.2) | 24 (2.6) | 19 (4.4) | 0.1 |
| Therapeutic interventions | ||||
| Non-invasive ventilationb prior to IMV | 921 (67.6) | 612 (65.6) | 309 (71.9) | 0.025 |
| Corticosteroids | 910 (66.8) | 606 (65) | 304 (70.7) | 0.042 |
| Interleukin-6 inhibitor | 117 (8.6) | 77 (8.3) | 40 (9.3) | 0.59 |
| Neuromuscular blockade | 1178 (86.4) | 803 (86.1) | 375 (87.2) | 0.626 |
| Prone position trial | 1054 (77.3) | 712 (76.3) | 342 (79.5) | 0.211 |
| Inhaled nitric oxide use | 168 (12.3) | 98 (10.5) | 70 (16.3) | 0.003 |
| Chest drain(s) for pneumothorax | 83 (6.1) | 55 (5.9) | 28 (6.5) | 0.749 |
| Renal replacement therapy | 135 (9.9) | 63 (6.8) | 72 (16.7) | < 0.001 |
| Noradrenaline dose (mcg/kg) | 0.04 [0, 0.12] | 0.03 [0, 0.1] | 0.06 [0.01, 0.19] | < 0.001 |
| Anticoagulation | < 0.001 | |||
| Contraindicated | 11 (0.8) | 7 (0.8) | 4 (0.9) | |
| Prophylactic | 883 (64.8) | 647 (69.3) | 236 (54.9) | |
| Therapeutic | 469 (34.4) | 279 (29.9) | 190 (44.2) | |
| Respiratory parameters at time of referral | ||||
| P/F ratio (mmHg) | 78.33 [64.7, 97.78] | 80 [67.28, 100.5] | 73.93 [61.5, 91.67] | < 0.001 |
| Static compliance (mL/cmH2O) | 28.87 [20.89, 35.71] | 30 [22, 37] | 26.4 [19.44, 33.72] | < 0.001 |
| Vt/PBW (mL/kg) | 6.7 [5.98, 7.87] | 6.74 [6.06, 7.99] | 6.55 [5.78, 7.61] | 0.001 |
| Driving pressure (cmH2O) | 16 [13, 20] | 15.7 [13, 19] | 17 [14, 22] | < 0.001 |
| Plateau pressure (cmH2O) | 29 [25, 31] | 29 [25, 31] | 29 [25, 32] | 0.065 |
| Positive end expiratory pressure (cmH2O) | 12 [10, 14] | 12 [10, 14.2] | 12 [10, 14] | 0.218 |
| Minute ventilation (L/min) | 9.84 [8, 11.52] | 9.88 [8.04, 11.5] | 9.65 [7.92, 11.63] | 0.715 |
| Arterial blood gas parameters at time of referral | ||||
| pH | 7.31 [7.24, 7.38] | 7.32 [7.25, 7.39] | 7.29 [7.2, 7.36] | < 0.001 |
| pCO2 (mmHg) | 59.62 [50.25, 71.03] | 58.12 [49.2, 68.55] | 63.9 [53.25, 77.25] | < 0.001 |
| Bicarbonate (mmol/L) | 27.02 [24, 31.45] | 26.98 [24.08, 30.75] | 27.6 [24, 32.6] | 0.066 |
| Base excess (mmol/L) | 3.73 [1.8, 7.8] | 3.6 [1.8, 7.4] | 4.05 [1.8, 8.4] | 0.219 |
| Lactate (mmol/L) | 1.3 [1, 1.8] | 1.3 [1, 1.7] | 1.4 [1, 1.8] | 0.111 |
| Laboratory parameters at time of referral | ||||
| Haemoglobin (g/L) | 113.55 [98, 126] | 115 [101, 127] | 108.5 [92, 124] | < 0.001 |
| White cell count (10ˆ9/L) | 12.04 [9.31, 15.55] | 11.86 [9.2, 15] | 12.91 [9.8, 16.88] | 0.001 |
| Platelets (10ˆ9/L) | 272.1 [229, 319.91] | 278.17 [235, 325] | 263.78 [218.14, 307.27] | < 0.001 |
| Creatinine (μmol/L) | 73 [56, 99.63] | 71 [55, 93] | 79 [59.25, 117.5] | < 0.001 |
| C-reactive protein (mg/L) | 165.63 [76.5, 270.1] | 170 [80, 274] | 148.47 [68, 260] | 0.1 |
| Severity and risk scores | ||||
| RESP score | 4 [2.13, 5] | 5 [3, 5] | 3 [1, 4] | < 0.001 |
| SOFA score | 5.90 [4, 8] | 5 [4, 7] | 7 [4, 8] | < 0.001 |
| Referral outcomes | ||||
| Meets NHS criteria | 608 (46.8) | 463 (52.7) | 145 (34.5) | < 0.001 |
| Perceived futility | 430 (31.5) | 243 (26) | 0 (0) | < 0.001 |
| Treated with ECMO | 243 (17.8) | 403 (43.2) | 314 (73) | < 0.001 |
| Died | 717 (52.6) | 463 (52.7) | 145 (34.5) | < 0.001 |
Values are expressed as median value [95% CI] or as n (%); p values for comparison statistics computed for ‘perceived futility’ vs other referral decision only
IMV invasive mechanical ventilation, P/F ratio partial pressure of arterial oxygen to fraction of inspired oxygen ratio, Vt tidal volume, PBW predicted body weight, RESP respiratory ECMO survival prediction, SOFA sequential organ failure assessment, NHS national health service
aIMV duration includes all days of IMV, regardless of intensity
bNIV use does not include high flow oxygen therapy