Table 3.

Comparison of accuracy (RMSE^a) and mean bias of SpO₂^b estimation between devices during the hypoxia exposure phase. There were 215 SaO₂ target windows in this phase.

Performance metrics	Philips MX450	CheckMe O2+	WristOx2 3150	AP-20	P value
Available SpO2 points, n	215	207	209	214	N/Ac
RMSE, % (95% CI)	2.67 (2.31-3.06)	3.20 (2.85-3.56)	3.33 (2.85-3.86)	2.86 (2.44-3.25)	N/A
Mean bias, %	0.49d	–0.22	–1.92e	–0.3d	<.001
Mean |bias|, %	1.92	2.42	2.40	2.00	<.02
Precision, %	2.62d	3.16d	2.73	2.83	<.02

^aRMSE: root-mean-square error.

^bSpO₂: peripheral oxygen saturation.

^cN/A: not applicable.

^dDifferent from each other.

^eDifferent from other values.