Table 1.

Work of breathing between devices and cannulas at baseline and under high flow oxygen therapy.

Device	Baseline		HFOT
	Nasal cannula	Tracheal cannula	Nasal cannula	Tracheal cannula
	Resistive WOB*, **		Resistive WOB*, **
Optiflow	2.7 (2.6–2.8)	2.4 (2.4–2.4)	2.4 (2.4–2.4)	2.2 (2.2–2.2)
Airvo2	2.6 (2.6–2.7)††	2.4 (2.4–2.4)	2.5 (2.5–2.5)††	2.2 (2.2–2.2)
C5	2.8 (2.8–2.8)††	2.4 (2.4–2.4)††	2.5 (2.5–2.5)††	2.2 (2.2–2.2)
HM80	2.8 (2.8–2.8)††	2.4 (2.4–2.4)	2.4 (2.4–2.4)††	2.2 (2.1–2.3)
T60	2.8 (2.8–2.8)††	2.4 (2.3–2.4)	2.5 (2.5–2.5)††	2.2 (2.2–2.2)
V500	2.8 (2.8–2.8)††	2.4 (2.4–2.4)	2.5 (2.5–2.5)††	2.2 (2.2–2.2)
V60	2.8 (2.8–2.8)††	2.4 (2.4–2.4)	2.4 (2.4–2.4)††	2.2 (2.2–2.3)††
	Elastic WOB*, **, †		Elastic WOB*, **, †
Optiflow	1.6 (1.6–1.7)	1.4 (1.4–1.4)	1.4 (1.3–1.4)	1.3 (1.2–1.3)
Airvo2	1.7 (1.6–1.8)††	1.4 (1.4–1.4)	1.4 (1.3–1.4)††	1.3 (1.2–1.3)††
C5	1.6 (1.6–1.6)††	1.4 (1.4–1.4)	1.4 (1.3–1.4)††	1.3 (1.2–1.3)
HM80	1.5 (1.5–1.6)††	1.4 (1.3–1.4)††	1.4 (1.3–1.4)	1.3 (1.2–1.3)††
T60	1.6 (1.5–1.6)††	1.4 (1.3–1.4)††	1.4 (1.3–1.4)††	1.3 (1.2–1.3)
V500	1.5 (1.5–1.6)††	1.4 (1.4–1.4)	1.4 (1.3–1.4)††	1.3 (1.2–1.3)
V60	1.6 (1.6–1.6)††	1.4 (1.4–1.4)	1.4 (1.3–1.4)	1.3 (1.2–1.3)††
	Total WOB*, **, †		Total WOB*, **, †
Optiflow	4.3 (4.3–4.3)	3.8 (3.7–3.8)	3.7 (3.7–3.8)	3.5 (3.5–3.5)
Airvo2	4.3 (4.3–4.3)	3.8 (3.7–3.8)	3.9 (3.9–3.9)††	3.5 (3.5–3.5)††
C5	4.4 (4.3–4.4)††	3.8 (3.8–3.8)	3.9 (3.9–4.0)††	3.5 (3.5–3.5)††
HM80	4.3 (4.3–4.3)††	3.8 (3.7–3.8)	3.8 (3.8–3.8)††	3.6 (3.5–3.6)††
T60	4.3 (4.3–4.4)	3.7 (3.7–3.7)††	3.9 (3.9–3.9)††	3.5 (3.5–3.5)††
V500	4.3 (4.3–4.3)	3.8 (3.8–3.8)††	3.9 (3.9–3.9)††	3.5 (3.5–3.5)††
V60	4.4 (4.3–4.4)††	3.8 (3.8–3.8)††	3.8 (3.8–3.8)††	3.5 (3.5–3.6)††

Values are medians (1st−3rd quartiles) and the unit is J/min.

HFOT, high flow oxygen therapy; WOB, work of breathing.

^*P < 0.05 for cannula,

^**P < 0.05 for device,

^†P < 0.05 for interaction between cannula and device,

^††P < 0.05 vs. Optiflow.