Table 1.
Patient characteristics, presentation, and outcomes according to maximum respiratory support.
| All Patients (n = 100) |
Invasive Mechanical Ventilation (n = 30) |
Non-Invasive Respiratory Support (n = 38) |
No Respiratory Support (n = 32) |
p | |
|---|---|---|---|---|---|
| Patient Characteristics | |||||
| Age (years) | 42.5 (32.0–53.3) | 43.0 (32.0–50.0) | 46.0 (32.5–55.8) | 41.0 (30.3–50.0) | 0.573 |
| Female sex | 67 (67) | 20 (70) | 26 (68) | 20 (63) | 0.869 |
| White ethnicity | 88 (88) | 27 (90) | 34 (89) | 27 (84) | 0.745 |
| Body Mass Index (kg/m2) | 27.7 (24.0–34.6) | 27.6 (23.9–37.1) | 29.1 (24.1–34.6) | 27.2 (23.7–33.3) | 0.755 |
| Charlson CI | 0 (0–2) | 0 (0–3) | 2 (0–3) | 0 (0–1) | 0.064 |
| Clinical Frailty Scale | 2 (1–3) | 2 (1–4) | 2 (1–4) | 1 (1–3) | 0.199 |
| Current smoker | 22 (22) | 7 (23) | 9 (24) | 6 (19) | 0.865 |
| Former smoker | 26 (26) | 8 (27) | 9 (24) | 8 (25) | 0.961 |
| COPD | 9 (9) | 0 (0) | 8 (21) | 1 (3) | <0.001 |
| Asthma Characteristics | |||||
| Previous ICU admission | 32 (32) | 13 (43) | 5 (13) | 14 (44) | 0.007 |
| Long-term oral steroids | 15 (15) | 5 (17) | 4 (11) | 6 (19) | 0.314 |
| Biologic therapy | 13 (13) | 3 (10) | 2 (5) | 7 (22) | 0.030 |
| Respiratory Data | |||||
| Respiratory rate (per min) | 28 (20–34) | 29 (17–37) | 30 (25–35) | 24 (19–32) | 0.099 |
| Heart rate (per min) | 112 (100–126) | 117 (102–130) | 114 (106–126) | 108 (94–123) | 0.274 |
| Clinically exhausted | 70 (70) | 26 (87) | 28 (74) | 16 (50) | 0.001 |
| Altered mental status | 29 (29) | 20 (67) | 8 (21) | 1 (3) | <0.001 |
| pH | 7.37 (7.30–7.41) | 7.28 (7.21–7.36) | 7.38 (3.35–7.42) | 7.39 (7.36–7.43) | <0.001 |
| PaO2/FiO2 ratio (mmHg) | 236 (155–313) | 209 (129–419) | 241 (158–314) | 245 (208–274) | 0.823 |
| PaCO2 (mmHg) | 39 (33–47) | 53 (43–69) | 39 (35–45) | 33 (30–38) | <0.001 |
| Bicarbonate (mmol/L) | 22.9 (19.9–25.9) | 24.7 (22.7–27.2) | 23.0 (19.9–26.6) | 20.5 (18.1–22.9) | <0.001 |
| Base excess (mmol/L) | −2.7 (−4.7–−0.1) | −3.2 (−4.5–−0.6) | −1.8 (−4.9–0.3) | −3.5 (−5.1–−1.9) | 0.284 |
| Lactate | 2.2 (0.9–4.4) | 1.2 (0.7–2.3) | 1.9 (0.9–3.8) | 4.2 (2.2–5.5) | 0.001 |
| Microbiology Data | |||||
| White cell count (×109/L) | 13.6 (10.4–18.6) | 17.3 (12.6–22.8) | 14.5 (10.9–17.0) | 11.5 (10.1–13.8) | 0.003 |
| Neutrophil count (×109/L) | 11.7 (8.8–15.7) | 14.4 (10.8–19.0) | 12.0 (8.8–14.9) | 10.0 (8.7–12.1) | 0.022 |
| Lymphocyte count (×109/L) | 0.8 (0.6–1.3) | 1.0 (0.6–1.4) | 0.8 (0.6–1.1) | 0.7 (0.6–1.2) | 0.636 |
| NLR | 14.0 (7.8–23.4) | 13.8 (7.3–31.6) | 14.8 (9.0–23.5) | 12.9 (7.3–17.9) | 0.593 |
| CRP (mg/L) | 22 (8–77) | 25 (11–82) | 41 (9–96) | 11 (5–27) | 0.028 |
| Proven viral infection | 18 (18) | 6 (20) | 9 (24) | 3 (9) | 0.112 |
| Proven bacterial infection | 8 (8) | 6 (20) | 2 (5) | 0 (0) | 0.003 |
| Patient Outcomes | |||||
| ICU length of stay (days) | 2.3 (1.3–4.4) | 5.1 (2.5–9.4) | 2.6 (1.4–3.4) | 1.3 (0.8–1.8) | <0.001 |
| ECMO/ECCO2R | 2 (2) | 2 (6) | 0 (0) | 0 (0) | 0.029 |
| In-ICU mortality | 1 (1) | 1 (3) | 0 (0) | 0 (0) | 0.125 |
| Twenty-eight-day mortality | 1 (1) | 1 (3) | 0 (0) | 0 (0) | 0.125 |
Abbreviations: Charlson CI, Charlson’s Comorbidity Index; COPD, chronic obstructive pulmonary disease; ICU, intensive care unit; NLR, neutrophil/lymphocyte ratio; CRP, C-reactive protein; ECMO, extracorporeal membrane oxygenation; ECCO2R, extra-corporeal carbon dioxide removal. Footnotes: Continuous data are presented as median (inter-quartile range) and categorical data as number (percentage). We compared the three sub-groups using Chi-squared and Kruskal–Wallis one-way ANOVA tests, with p values representing results of this comparison.