Table 4.

Acare AH-M1 SpO₂ bias and A_RMS statistics for differences from SpO₂ at Hct = 40%

O2Hb range	HCT = 30		HCT = 20		HCT = 10
	Bias (%)	ARMS (%)	Bias (%)	ARMS (%)	Bias (%)	ARMS (%)
60–69.9	− 0.82	0.83	− 1.96	1.97	− 5.97	5.98
70–79.9	− 0.97	0.97	− 1.24	1.26	− 4.56	4.59
80–89.9	− 0.59	0.62	− 0.29	0.42	− 2.25	2.39
90–100	0.31	0.46	0.88	0.96	0.97	1.45
70–100	− 0.41	0.71	− 0.21	0.95	− 1.93	3.10

For each device, the curve fit at hematocrit 40% was used as a “reference” performance level and was subtracted from the curve fits at hematocrits of 30%, 20%, and 10%. The bias (%) and A_RMS (%) were calculated over the 70–100% O₂Hb range and at each 10% O₂Hb range down to 60%. A_RMS is used to characterize pulse oximeter accuracy and A_RMS greater than 3% used as a threshold for inaccuracy