Table 1.
Baseline characteristics
| Characteristic | COVID-19 patients | Controls (N = 23) |
||
|---|---|---|---|---|
| All (N = 50) |
VS + (N = 11) |
VS − (N = 39) |
||
| Population factors | ||||
| Age, years | 59.6 ± 13.6 | 62.7 ± 7.5 | 58.8 ± 15.0 | 45.4 ± 10.6 |
| Female sex, n (%) | 8 (16) | 0 (0.0) | 8 (20.5) | 14 (60.9) |
| Body mass index, kg/m2 | 26.4 ± 4.0 | 28.1 ± 4.2 | 25.9 ± 3.4 | 25.2 ± 4.7 |
| Caucasian or white race/ethnicity, n (%) | 44 (88) | 10 (90.9) | 34 (87.2) | 19 (82.6) |
| History | ||||
| History of hypertension, n (%) | 26 (52) | 9 (81.8) | 17 (43.6) | 1 (4.3) |
| History of cardiovascular disease, n (%) | 4 (8) | 1 (9.1) | 3 (7.7) | 0 (0.0) |
| History of diabetes, n (%) | 8 (16) | 2 (18.2) | 6 (15.4) | 0 (0.0) |
| Current smoking, n (%) | 6 (12) | 3 (27.3) | 3 (7.7) | 0 (0.0) |
| Current medications | ||||
| β-blockers, n (%) | 4 (8) | 1 (9.1) | 3 (7.7) | 0 (0.0) |
| ACE-inhibitors, n (%) | 9 (18) | 4 (36.4) | 5 (12.2) | 0 (0.0) |
| ARB, n (%) | 4 (8) | 2 (18.2) | 2 (5.1) | 0 (0.0) |
| Clinical presentation at admission | ||||
| Baseline SpO2, % | 94.5 ± 4.6 | 89.9 ± 6.6 | 95.8 ± 2.3 | 97.6 ± 1.0 |
| PaO2 at admission, mmHg* | 76.2 ± 15.3 | 71.0 ± 16.4 | 77.7 ± 14.9 | – |
| PaCO2 at admission, mmHg* | 36.4 ± 5.4 | 37.0 ± 4.6 | 36.2 ± 6.0 | – |
| Baseline Heart rate, beats/min | 86.8 ± 16.8 | 86.2 ± 21.0 | 86.9 ± 13.6 | – |
| Baseline systolic blood pressure, mmHg | 127.3 ± 19.1 | 126.5 ± 18.8 | 127.5 ± 19.8 | – |
| Baseline diastolic blood pressure, mmHg | 78.5 ± 10.8 | 74.4 ± 12.5 | 79.7 ± 10.2 | – |
| Anosmia, n (%) | 11 (22.0) | 1 (9.1) | 10 (25.6) | – |
| Ageusia, n (%) | 12 (24.0) | 2 (18.2) | 10 (25.6) | – |
| Gastrointestinal symptoms, n (%) | 13 (26.0) | 2 (18.2) | 11 (28.2) | – |
| Dyspnea presence, n (%) | 13 (26.0) | 3 (27.3) | 10 (25.6) | – |
| Laboratory tests | ||||
| C-reactive protein, mg/L | 20.2 ± 41.9 | 14.6 ± 23.7 | 21.8 ± 15.0 | – |
| D-dimer, μg/L | 0.8 ± 0.8 | 1.1 ± 0.8 | 0.7 ± 0.9 | – |
| Breath-holding measurements | ||||
| Mean desaturation, % | 2.34 ± 1.78 | 4.42 ± 2.37 | 2.21 ± 1.43 | 1.57 ± 1.24 |
| Maximal breath-hold duration**, s | 46.8 ± 16.9 | 51.8 ± 12.7 | 41.8 ± 14.2 | 53.0 ± 20.3 |
| Recovery breath, %baseline | 188.9 ± 61.3 | 184.6 ± 81.8 | 195.0 ± 62.1 | 180.5 ± 49.4 |
| Outcomes | ||||
| Discharge:oxygen:ventilatory support, n | 14:36:11 | 0:11:11 | 14:25:0 | – |
| Duration of hospitalization, days | 29.8 ± 17.2 | 47.4 ± 12.5 | 24.8 ± 15.3 | – |
Data are expressed as mean ± SD or as N (%). Patients who met the criteria for the adverse primary composite outcome are denoted “VS + ” (N = 4 non-invasive bi-level pressure support, N = 7 intensive care, N = 1 death). In all patients, diagnosis was confirmed with a positive nasal or pharyngeal swab. All patients admitted to ICU were administered mechanical ventilatory support; the patient who died was also in intensive care on mechanical ventilatory support. “VS − “ indicates patients discharged without meeting adverse primary outcome criteria. Average time to the primary outcome in VS + patients was 6 [2] days (median [IQR]). Non-Caucasian/Non-White race/ethnicities were black (1 VS + and 1 VS − COVID-19 patients), Hispanic (3 VS + COVID-19 patients) and Asian (1 VS − COVID-19 patient and 4 controls). Note that participants included in the table are those who provided data for all breath-holding measures. “Discharge” indicates discharge without oxygen or interventions that met criteria for the primary outcome during the hospital stay. On average, 3.8 ± 1.0 20-s breath-holds per individual were analyzed to calculate the ventilatory response variable (3.6 ± 0.9 in controls); 1.6 ± 0.6 maximal breath-holds were used to determine maximal breath-hold duration (2.1 ± 0.5 in controls); 5.2 ± 1.1 breath-holds (20-s or maximal) were used to calculate mean desaturation (6.3 ± 1.1 in controls). *Data available for 42 patients (9 VS + and 33 VS −). Abbreviations: SpO2, peripheral oxyhemoglobin saturation; PaO2, partial pressure of oxygen; PaCO2, partial pressure of carbon dioxide; ACE, angiotensin converting enzyme; ARB, angiotensin II receptor blockers. **Data shown are adjusted for baseline SpO2 and mean desaturation (regression)