Closed-loop oxygen control improves oxygen therapy in acute hypoxemic respiratory failure patients under high flow nasal oxygen: a randomized cross-over study (the HILOOP study)

Roca, Oriol; Caritg, Oriol; Santafé, Manel; Ramos, Francisco J.; Pacheco, Andrés; García-de-Acilu, Marina; Ferrer, Ricard; Schultz, Marcus J.; Ricard, Jean-Damien

doi:10.1186/s13054-022-03970-w

Critical Care

Table 3 Primary and secondary outcomes

From: Closed-loop oxygen control improves oxygen therapy in acute hypoxemic respiratory failure patients under high flow nasal oxygen: a randomized cross-over study (the HILOOP study)

Variable	Closed-loop oxygen control	Manual oxygen titration	Difference estimate (95% CI) or mean difference or OR	p value
Primary outcome
Time in optimal SpO₂ range (% of the total recording time)	96.5 (93.5 to 98.9)	89.0 (77.4 to 95.9)	10.40 (5.20 to 17.20)	< 0.0001
Secondary outcomes
Time in suboptimal SpO₂ range (% of the total recording time)
Low	0.6 (0.1 to 1.1)	1.0 (0.1 to 4.0)	− 1.20 (− 4.95 to − 0.25)	0.0053
High	2.3 (0.8 to 5.2)	4.2 (1.1 to 16.4)	− 5.25 (− 14.45 to − 1.40)	0.0004
Time out of SpO₂ range (% of the total recording time)
Low	0 (0 to 0)	0 (0 to 0.1)	− 0.10 (− 0.35 to 0.10)	0.3972
High	0 (0 to 0.1)	0 (0 to 0.3)	− 0.50 (− 2.15 to − 0.05)	0.0166
Percentage of time with SpO₂ signal available	99.7	99.8	− 0.10 (− 0.35 to 0.30)	0.6235
Mean SpO₂/F_IO₂ during the recording time	206 (176 to 254)	210 (165 to 235)	8.21 (− 7.08 to 23.38)	0.2715
ROX index
At the beginning	10.30 (3.22)	10.30 (2.87)	Mean difference 0.009 (− 0.83 to 0.85)	0.9829
At the end	11.50 (4.48)	10.60 (3.52)	Mean difference 0.88 (− 0.46 to 2.23)	0.1916
ΔROX^a	1.20 (4.20)	0.33 (2.37)	Mean difference 0.87 (− 0.77 to 2.52)	0.2917
Time with SpO₂ < 88% (% of the total recording time)	0 (0 to 0)	0 (0 to 0)	− 0.10 (− 0.20 to 0.05)	0.2470
Time with SpO₂ < 85% (% of the total recording time)	0 (0 to 0)	0 (0 to 0)	− 0.10 (− 0.55 to 0.10)	0.3741
Number of events (SpO₂ < 88%) per hour	0 (0 to 0)	0 (0 to 0)	0.05 (− 0.38 to 0.38)	0.9055
Number of events (SpO₂ < 85%) per hour	0 (0 to 0)	0 (0 to 0)	− 0.25 (− 0.51 to 0.25)	0.5862
Mean F_IO₂ during the recording time	0.5 (38.1 to 55.8)	0.5 (40.0 to 56.6)	0.75 (− 2.80 to 4.55)	0.6155
Time in different F_IO₂ (% of the total recording time)
F_IO₂ < 0.4	21.7 (0 to 66.0)	0 (0 to 0)	32.29 (12.05 to 50.30)	0.0025
F_IO₂ 0.4–0.6	46.0 (10.3 to 70.2)	100 (63.2 to 100)	− 41.08 (− 54.80 to − 23.80)	< 0.0001
F_IO₂ > 0.6	4.2 (0.0 to 29.8)	0.0 (0.0 to 0.0)	16.43 (6.40 to 35.20)	< 0.0001
Number of manual adjustments per hour	0 (0 to 0)	0.21 (0 to 0.47)	− 0.49 (− 0.72 to − 0.36)	< 0.0001
Patients with ≥ 1 alarms/h for low SpO₂	16 (35.6%)	22 (48.9%)	OR 0.57 (0.25–1.34)	0.2003
Patients with ≥ 1 alarms/h for high SpO₂	1 (2.2%)	1 (2.2%)	OR 1.00 (0.06–16.49)	1.0000
ΔComfort score^a	0 (0 to 1.0)	0 (− 0.25 to 0.125)	1.0 (0 to 1.50)	0.0468

Results are shown as median (interquartile range, IQR) or as mean (standard deviation, SD). Wilcoxon or student’s t test were performed depending on each variable distribution according to the Shapiro–Wilk test. For alarms, a Fisher’s exact test was performed
OR odds ratio, 95% CI 95% confidence interval
^aΔROX and ΔComfort score were calculated as the value at the end of the period minus the value at the beginning of the period. SpO₂: pulse oximetry; F_IO₂: fraction of inspired oxygen; ROX: respiratory rate and oxygenation index ([SpO₂/F_IO₂]/RR)

Back to article page

ISSN: 1364-8535

Contact us

Submission enquiries: journalsubmissions@springernature.com