TABLE 1.
Demographic and blood gas characteristics at baseline.
| COVID-19 (n = 100) | Non-COVID-19 (n = 100) | p | |
| Age (years) | 62 [48–72] | 66.5 [52–76] | NS |
| Sex | |||
| Male | 70 | 69 | |
| Female | 30 | 31 | |
| NS | |||
| Body mass index* (kg.m–2) | 29.5 [26.1–31.3] | 25.4 [21.9–29.9] | 0.0002 |
| Smoking history | |||
| Never smoker | 51 | 39 | |
| Former smoker | 28 | 36 | |
| Current smoker | 4 | 16 | |
| Not available | 17 | 9 | |
| 0.009 | |||
| Pack-years# | 20 [11–50] | 30 [16–50] | NS |
| Place of first sample | |||
| Emergency room | 84 | 67 | |
| Ward | 12 | 22 | |
| Intensive care unit | 4 | 11 | |
| 0.017 | |||
| Severity | |||
| Ambient air | 51 | 70 | |
| Low dose O2 (1-6 l.min–1) | 35 | 21 | |
| High dose O2 (≥7 l.min–1 or ventilation) | 14 | 9 | |
| 0.023 | |||
| Blood gas variables | |||
| Temperature (°C) | 37.9 [37–38.7] | 37 [36.5–37.1] | <0.0001 |
| PO2 (mmHg) | 75.8 [65–93] | 72.6 [60.2–84] | – |
| PCO2 (mmHg) | 35.7 [32–39.5] | 38 [31.8–43.2] | – |
| pH | 7.44 [7.41–7.47] | 7.42 [7.38–7.46] | – |
| Hemoglobin (g.dl–1) | 14 [12.6–15.2] | 13.2 [11.4–14.7] | 0.006 |
| Oxyhemoglobin (%) | 93.2 [90.4–95.5] | 92.6 [88.6–94.4] | – |
| Oxygen content (ml.100 ml–1) | 18.2 [16.4–20.1] | 16.9 [14.1–19] | – |
| Carboxyhemoglobin (%) | 0.9 [0.7–1.1] | 1.3 [0.8–1.7] | – |
| Methemoglobin (%) | 1.1 [1–1.2] | 0.8 [0.6–1.1] | <0.0001 |
| P50⨎ (mmHg) | 26 [25.2–26.8] | 25.9 [24–27.3] | NS |
Data are presented as numbers, or medians and interquartile ranges between square brackets. Some blood gas variables were not statistically compared because of the patients receiving oxygen therapy. NS, non-significant.*BMI: the number of available values was 70 and 76 for each group, respectively.#Tobacco consumption: the number of available values was 28/32 and 44/52 for each group, respectively.⨎P50: the number of exploitable values (saturation < 97%) was 69 and 79 for each group, respectively. Bold values are significant p-values (i.e., under 0.05).