Table 1

Baseline clinical characteristics of study participants and the environment of care provision.

AllSOCCPAPHFNOStatistically significant differences
Number of participants 30101010
Male (n)
17656
Mean age (95% CI) (min max)56(52 to 60) (35–75)54(47 to 61) (35–74)60(52 to 68) (44–75)53(45 to 61) (39–68)p=NS (ANOVA)
Ethnicity
Asian – Pakistani (n)10262
White - British (n)8404
Not given (n)4130
Asian - Indian (n)3003
Asian - other (n)2101
White - other (n)1100
Caribbean (n)1100
Mixed – White and Caribbean (n)1010
Mean number of days of illness at time of hospital admission (95% CI) (min–max)9(8 to 11) (0–17)8(5 to 11) (2–15)8(6 to 11)) (3–12)11(8 to 14) (0–15)p=NS (ANOVA)
Mean number of days of illness at time of sampling (95% CI) (min–max)12(10 to 14) (3–25)9(5 to 13) (3–18)13(9 to 16) (6–24)16(13 to 19) (11–25)p=0.02 (ANOVA) SOC vs CPAP p=NS (unpaired t-test) SOC vs HFNO p<0.01 (unpaired t-test)
Median number of days in hospital at the time of sampling (IQR) (min–max)2(1–5) (0–14)1 (0–2) (0–3)4.5(2–6) (1–9)3(2–6) (2–14)p<0.01 (Kruskal-Wallis) SOC vs CPAP p<0.01 (Mann-Whitney) SOC vs HFNO p<0.01 (Mann-Whitney)
Mean number of days CPAP/HFNO at time of sampling (95% CI) (min–max)N/AN/A2.4 [1.5–3.3] (1-4)1.8 [1.0–2.6] (0–3)
Median FiO2 at time of sampling (IQR) (min-max)56(40 to 73) (35–98)59(40 to 65) (40–98)48(40 to 62) (40–80)63(40 to 91) (35–98)p=NS (Kruskal-Wallis)
Mean SpO2 at time of sampling (95% CI mean) (min–max)94(93 to 95) (92–99)95(93 to 96) (92–99)94(93 to 95) (92–96)94(93 to 96) (92–98)p=NS (ANOVA)
Room type
Open bay/cohort area12444
Side room – ambient pressure8503
Side room – negative pressure7061
Side room – natural airflow3102
Estimated air changes per hour
1015666
4–610442
42002
Mean room air temperature (°C) at time of sampling (95% CI) (min–max)21.9(21 to 23) (18.0–25.0)23.2(22 to 24) (20.0–25.0)21.9(21 to 23) (19.0–24.0)20.7(19 to 22) (18.0–23.0)p=0.01 (ANOVA) SOC vs CPAP p=NS (unpaired t-test) SOC vs HFNO p<0.01 (unpaired t-test)
Median room air CO2 content (ppm) at time of sampling (IQR) (min–max)574.5(500–808) (419–1548)672.5(530–774) (459–1548)502.0(448–582) (419-618)915.0 (459–1303) (506–1460)p=0.01 (Kruskal-Wallis) SOC vs CPAP p=0.02 (Mann-Whitney) SOC vs HFNO p=NS (Mann-Whitney)
Mean room air humidity (%) at time of sampling (95% CI mean) (min–max)37.6(34 to 41)(22.0–58.0)37.5(32 to 43)(23.0–41.0)30.4(26 to 35)(23.0–41.0)44.8(37 to 53)(26.0–58.0)p<0.01 (ANOVA) SOC vs CPAP p=0.03 (unpaired t-test) SOC vs HFNO p=NS (unpaired t-test)
Receiving humidified oxygen (n) 15627
CPAP full face mask (unvented) (n) N/AN/A8N/A
CPAP partial face mask (vented) (n) N/AN/A2N/A
  • A total of 30 participants with moderate/severe COVID-19 were enrolled into the study. Paired t-tests were post-hoc analysis of differences between SOC and CPAP/HFNO study groups only.

  • ANOVA, analysis of variance; CPAP, continuous positive airway pressure; FiO2, fraction of inspired oxygen; HFNO, high-flow nasal oxygen; N/A, not applicable; NS, not significant; SOC, supplemental oxygen care; SpO2, oxygen saturation.