Table 3.

Arterial Blood Gas Results

	Before Intervention			After Intervention (at 120 Minutes)			Within‐group Difference‡ (95% CI); p‐value
	COT (n = 12)	NHF (n = 18)	Difference* (95% CI); p‐value	COT (n = 11)	NHF (n = 18)	Difference† (95% CI); p‐value	COT (n = 12)	NHF (n = 18)
pH	7.39 ± 0.07	7.37 ± 0.05	0.02 (–0.02 to 0.07); p = 0.35	7.40 ± 0.04	7.37 ± 0.05	0.03 (–0.002 to 0.05); p = 0.06	–0.01 (–0.04 to 0.03); p = 0.62	0.002 (–0.02 to 0.02); p = 0.84
pHadj				7.39 (0.01)	7.37 (0.01)	0.02 (–0.01 to 0.05); p = 0.12
PaCO2	37.4 ± 13.4	39.4 ± 7.6	–2.0 (–11.1 to 7.1); p = 0.65	33.3 ± 7.4	37.9 ± 8.7	–4.6 (–11.2 to 1.9); p = 0.16	2.8 (–2.7 to 8.3); p = 0.29	1.5 (–0.5 to 3.5); p = 0.13
PaCO2adj				34.6 (1.5)	37.7 (1.2)	–2.4 (–6.3 to 1.5); p = 0.22
PaO2	161.4 ± 72.4	134.0 ± 48.4	27.4 (–17.6 to 72.4); p = 0.22	139.4 ± 48.9	119.2 ± 37.0	20.2 (–12.6 to 53.0); p = 0.22	31.8 (–5.8 to 69.4); p = 0.09	14.8 (–6.1 to 35.8); p = 0.11
PaO2 adj				129.8 (11.0)	125.0 (8.5)	4.7 (–24.6 to 34.0); p = 0.74
P/F ratio	334.5 ± 67.3	272.2 ± 59.3	62.3 (14.5 to 110.0); p = 0.01	337.3 ± 162.2	306.9 ± 108.9	30.4 (–72.6 to 133.4); p = 0.55	4.3 (–93.0 to 101.5); p = 0.92	–34.7 (–90.3 to 20.9); p = 0.21
P/F ratioadj				306.9 (41.6)	325.4 (31.5)	–18.4 (–132.3 to 95.4); p = 0.63
HCO3	24.1 ± 4.3	24.4 ± 6.0	–0.2 (–4.4 to 3.9); p = 0.91	22.4 ± 4.0	21.9 ± 4.2	0.4 (–2.8 to 3.7); p = 0.78	1.3 (–0.02 to 2.6); p = 0.05	2.5 (–0.6 to 5.5); p = 0.11
HCO3adj				22.5 (1.1)	21.8 (0.9)	0.7 (–2.2 to 3.6); p = 0.63

Data are presented as mean ± SD or adjusted mean (SE).

COT = conventional oxygen therapy; HCO₃ = bicarbonate; NHF = nasal high flow; PaCO₂ = arterial partial pressure of carbon dioxide, PaO₂ = arterial partial pressure of oxygen; P/F = PaO₂/fraction of inspired oxygen.

^*Independent‐sample t‐test.

^†Independent‐sample t‐test and analysis of covariance adjusted for baseline values of that outcome variable.

^‡Before–after paired‐sample t‐test.