Table 1.
Baseline characteristics
| Characteristic | Sildenafil group (n = 20) | Placebo group (n = 20) | Total (n = 40) |
|---|---|---|---|
| Age (years) (median, IQR) | 59 (41–69) | 57 (45–67) | 57 (41–68) |
| Male sex (n, %) | 16 (80%) | 17 (85%) | 33 (82.5%) |
| Symptom duration (days) (median, IQR) | 9 (7–11) | 8 (6.5–10) | 8 (7–10) |
| Active smoker (n, %) | 3 (15%) | 2 (10%) | 5 (12.5%) |
| Asthma (n, %) | 1 (5.0%) | 1 (5.0%) | 2 (5.0%) |
| Chronic obstructive pulmonary disease (n, %) | 0 (0%) | 0 (0%) | 0 (0%) |
| Arterial hypertension (n, %) | 10 (50%) | 10 (50%) | 20 (50%) |
| Diabetes mellitus (n, %) | 4 (20%) | 4 (20%) | 8 (20%) |
| Charlson comorbidity index score (median, IQR) | 1 (0–3) | 1 (0–3) | 1 (0–3) |
| Ambient oxygen (n, %) | 6 (30%) | 7 (35%) | 13 (32.5%) |
| Awake prone positioning (n, %) | 5 (25%) | 6 (30%) | 11 (27.5%) |
| High-flow nasal cannula (n, %) | 1 (5%) | 1 (5%) | 2 (5%) |
| Oxygen support flow (Lts/min, median, IQR) | 1 (0–4.5) | 2.5 (0–5) | 2 (0–5) |
| Laboratory | |||
| Arterial pH (median, IQR) | 7.45 (7.43–7.48) | 7.45 (7.43–7.47) | 7.45 (7.44–7.47) |
| Arterial oxygen partial pressure (PO2, mmHg) (median, IQR) | 83.3 (70.7–87.5) | 84.1 (76.5–95.0) | 83.3 (75.4–90.1) |
| Arterial carbon dioxide partial pressure (mmHg) (median, IQR) | 33 (31.2–34.7) | 36.2 (31.3–37.7) | 33.4 (31.2–36.9) |
| Bicarbonate (mEq/Lt) (median, IQR) | 23.7 (21.3–25.1) | 24.2 (22.6–26.9) | 24.0 (22.4–25.6) |
| PaO2/FiO2 ratio (median, IQR) | 308 (216–366) | 299 (220–359) | 302 (216–365) |
| A-a gradients (median, IQR) | 51.6 (40.3–133) | 71.0 (37.3–149) | 66 (40–146) |
| D-Dimer (ng/mL) (median, IQR) | 271 (191–404) | 287 (170–545) | 284 (190–424) |
| Absolute lymphocyte count (cells/mm3) (median, IQR) | 860 (730–1200) | 860 (680–1120) | 860 (680–1160) |
| Lactate dehydrogenase (UI/L) (median, IQR) | 320 (252–355) | 310 (271–488) | 316 (254–398) |
| C-Reactive protein (mg/L) (median, IQR) | 90.3 (35.6–187.0) | 98.0 (63.3–139.0) | 92.5 (56.6–179) |
| Serum creatinine (mg/dL) (median, IQR) | 0.87 (0.79–1.0) | 0.78 (0.73–0.87) | 0.82 (0.75–0.93) |
| Serum blood urea nitrogen (mg/dL) (median, IQR) | 18.2 (14.9–20.6) | 15.2 (11.0–18.1) | 16.7 (12.5–19.6) |
| Computed tomography | |||
| Pulmonary embolism (n, %) | 0 (0%) | 1 (5.0%) | 1 (2.5%) |
| Vascular beaded appearance (n, %) | 11 (55%) | 10 (50%) | 21 (52.5%) |
| CT severity score (median, IQR) | 9 (7–10) | 9 (7.5–10) | 9 (7–10) |
| sCTA perfusion score (median, IQR) | 10 (8–10) | 10 (8–10) | 10 (8–10) |