Table 2. Population characteristics: admission biology and severity scores according to HFOT failure.
N, total patients included; n, number of patients in the category; HFOT, high-flow oxygen therapy; N/L, neutrophil-to-lymphocyte ratio; PLT, platelets count; PLR or P/L ratio, platelet-to-lymphocyte ratio; SII, systemic immune inflammation index; CRP, C reactive protein; chest CT, chest computed tomography; SOFA, Sequential Organ Failure Assessment; APACHE, Acute Physiology and Chronic Health Evaluation; SAPS, Simplified Acute Physiology Score; COT, conventional oxygen therapy; RR, respiratory rate; FiO2, fraction of inspired oxygen; SpO2, pulse oximetry; PaO2, partial pressure of oxygen in arterial blood
| Characteristics | Mean and range (N = 52) | HFOT | P-value | |
| Success (n = 21) | Failure (n = 31) | |||
| Admission biology | ||||
| White blood cell count/mm3 | 9,730 (7,345, 13,532) | 9,510 (7,535, 11,280) | 9,950 (7,305, 14,170) | 0.94 |
| Neutrophils (mm3) | 8,379 (5,730, 11,228) | 8,282 (5,984, 10,060) | 8,577 (5,668, 12,440) | 0.58 |
| Lymphocytes(mm3) | 631 (382, 860) | 757 (370, 1,102) | 598 (382, 767) | 0.41 |
| N/L ratio | 13 (7, 25) | 11 (6, 18) | 13 (8, 25) | 0.45 |
| PLT × 103 (mm3) | 230 (188, 280) | 256 (184, 278) | 214 (188, 280) | 0.62 |
| P/L ratio (PLR) | 0.37 (0.22, 0.59) | 0.44 (0.19, 0.61) | 0.35 (0.25, 0.56) | 0.94 |
| SII (×109 cells/L) | 673 (51, 2,777) | 777 (58, 2,808) | 261 (38, 2,147) | 0.79 |
| CRP (mg/dL) | 107 (77, 174) | 91 (56, 114) | 116 (92, 208) | 0.027 |
| Fibrinogen (mg/dL) | 645 (532, 734) | 623 (574, 720) | 687 (532, 760) | 0.31 |
| Severity scores, first 24 hours | ||||
| Days before ICU admission | 2.00 (0.00, 5.00) | 1.00 (0.00, 4.00) | 2.00 (0.00, 6.00) | 0.37 |
| Chest CT COVID-19 ground glass findings (%) | 60 (50, 75) | 50 (30, 60) | 70 (50, 75) | 0.009 |
| SOFA score at 24 hours | 2.00 (2.00, 4.00) | 2.00 (2.00, 3.00) | 3.00 (2.00, 4.00) | 0.047 |
| APACHE II | 11.0 (8.0, 13.0) | 9.0 (8.0, 12.0) | 11.0 (9.2, 13.0) | 0.13 |
| SAPS III | 3.0 (2.0, 6.0) | 2.0 (1.0, 4.0) | 3.5 (2.0, 6.0) | 0.13 |
| COT before HFOT (days) | 1.00 (1.00, 2.00) | 1.00 (1.00, 2.00) | 1.00 (1.00, 2.00) | 0.57 |
| HFOT (days) | 4.0 (3.0, 6.0) | 5.0 (3.0, 6.0) | 3.0 (2.0, 5.0) | 0.060 |
| Days till endpoint | 5.0 (3.8, 8.0) | 6.0 (5.0, 7.0) | 5.0 (3.0, 8.0) | 0.29 |
| RR, mean first 24 hours | 22.9 (20.3, 26.6) | 22.1 (19.7, 23.3) | 25.3 (20.9, 28.1) | 0.037 |
| FiO2, mean first 24 hours | 0.74 (0.56, 0.88) | 0.56 (0.52, 0.70) | 0.88 (0.74, 0.90) | <0.001 |
| SpO2, mean first 24 hours | 92.8 (91.3, 94.1) | 93.6 (92.7, 95.0) | 92.4 (91.1, 93.3) | 0.010 |
| PaO2, mean first 24 hours | 71 (67, 76) | 73 (71, 83) | 70 (64, 73) | 0.004 |
| PaO2/FiO2, mean first 24 hours | 98 (80, 137) | 137 (126, 147) | 82 (73, 98) | <0.001 |
| ROX index, mean first 24 hours | 6.15 (4.49, 7.67) | 7.71 (6.68, 9.08) | 5.13 (4.06, 6.38) | <0.001 |
| Modified ROX index, mean first 24 hours | 4.89 (3.41, 6.23) | 6.79 (5.43, 7.25) | 4.08 (2.82, 4.82) | <0.001 |
| Outcomes | ||||
| Dead | 22 (42%) | 1 (4.8%) | 21 (68%) | <0.001 |