Table 1. Baseline Characteristics in the Primary Analysis Population in the Helmet Noninvasive Ventilation and Usual Respiratory Support Groups.
| Characteristica | No. (%) | |
|---|---|---|
| Helmet noninvasive ventilation (n = 159) | Usual respiratory support (n = 161) | |
| Age, median (IQR), y | 57 (47-66) | 59 (50-67) |
| Sex | ||
| Women | 57 (35.8) | 76 (47.2) |
| Men | 102 (64.2) | 85 (52.8) |
| BMI, median (IQR) | 30.1 (26.7-35.2) | 29.9 (26.7-34.7) |
| Location before ICU admission | ||
| Emergency department | 86 (54.1) | 86 (53.4) |
| Hospital ward | 46 (28.9) | 54 (33.5) |
| Transfer from outside hospital ICU or ward | 27 (17.0) | 21 (13.0) |
| APACHE II score, median (IQR)b | 13 (10-16) | 14 (10-17) |
| SOFA score, median (IQR)b | 2 (2-4) | 3 (2-4) |
| Comorbiditiesc | ||
| Any chronic comorbidityc | 108 (67.9) | 117 (72.7) |
| Diabetes | 86 (54.1) | 95 (59.0) |
| Chronic cardiac disease | 57 (35.8) | 52 (32.3) |
| Chronic pulmonary disease | 24 (15.1) | 19 (11.8) |
| Chronic kidney disease with dialysis | 8 (5.0) | 8 (5.0) |
| Malignancy | 8 (5.0) | 10 (6.2) |
| Confirmed COVID-19 at enrollmentd | 156 (98.1) | 157 (97.5) |
| Physiologic parameters before randomization, median (IQR) | ||
| Pao2, mm Hg | 60 (52-70) | 60 (54-70) |
| Fio2 | 80 (70-100) | 80 (60-100) |
| Pao2:Fio2 ratio | 73 (60-93) | 76 (61-111) |
| Pco2, mm Hg | 36 (32-39) | 35 (32-39) |
| Hco3, mEq/L | 24 (22-26) | 24 (22-26) |
| pH | 7.43 (7.40-7.46) | 7.43 (7.40-7.46) |
| Quadrants with infiltrates on chest radiograph, No. (IQR)e | 4 (3-4) | 4 (3-4) |
| Respiratory support at baseline | ||
| High-flow nasal oxygen | 93 (58.5) | 78 (48.4) |
| Mask noninvasive ventilation | 45 (28.3) | 64 (39.8) |
| Standard oxygenf | 21 (13.2) | 19 (11.8) |
| Respiratory rate, median (IQR), breaths/min | 31 (27-35) | 30 (26-33) |
| Awake prone positioning | 30 (18.9) | 26 (16.1) |
| Days from onset of symptoms to emergency department visit, median (IQR) | 6 (3-8) | 5 (3-8) |
| Days from onset of symptoms to ICU admission, median (IQR) | 8 (5-10) | 7 (5-11) |
| Days from ICU admission to randomization, median (IQR) | 2 (1-2) | 2 (1-2) |
| Organ support | ||
| Vasopressors | 13 (8.2) | 12 (7.5) |
| Kidney replacement therapy for acute kidney injury | 0 | 3 (1.9) |
Abbreviations: BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); Fio2, fraction of inspired oxygen; ICU, intensive care unit; SOFA, Sequential [Sepsis-related] Organ Failure Assessment.
The number of patients for each variable is the total number of patients in the respective group. There were no missing values. Percentages may not total to 100 because of rounding. Additional details on baseline characteristics are provided in eTable 8 in Supplement 2.
The APACHE II score measures severity of illness and is based on age, medical history, and physiologic parameters. The score ranges from 0 to 71, with higher scores indicating more severe disease and higher risk of death. The SOFA score ranges from 0 to 24, with higher scores indicating a greater degree of organ dysfunction.
Data on comorbidities were obtained from the medical record. Other comorbidities included mild, moderate, or severe liver disease; chronic neurologic disease, hemiplegia or paraplegia, or dementia; and AIDS/HIV and rheumatologic diseases (eTable 8 in Supplement 2).
COVID-19 infection was confirmed by polymerase chain reaction test for SARS-CoV-2 from respiratory specimens. After the results of testing were obtained at enrollment, additional patients were confirmed to have COVID-19, totaling 157 of 159 (98.7%) in the helmet noninvasive ventilation group and 160 of 161 (99.4%) in the usual respiratory support group. No patients received a diagnosis by rapid antigen test or solely by clinical criteria.
The number of quadrants with infiltrates on chest radiograph was reported as determined by research coordinator review of images and confirmed subsequently with radiology reporting.
Standard oxygen included oxygen delivery via any device other than high-flow nasal cannula or noninvasive ventilation regardless of the Fio2 delivered to the patient.