Table 1. Between-day imprecision of the Point-of-Care Siemens RAPIDPoint 500 blood gas system (POC).

	Level 1			Level 2			Level 3			Average CV (%)
	QC	Mean	CV (%)	QC	Mean	CV (%)	QC	Mean	CV (%)
Na+, mmol/L	115	115.2	0.32	135	135	0.21	155	155	0.3	0.28
K+, mmol/L	3	3	0.53	5	5	0.28	7	7	0.21	0.34
Cl-, mmol/L	80	80	0.23	100	99.2	0.82	120	117.8	1.25	0.77
pH	7.15	7.15	0.06	7.35	7.35	0.04	7.55	7.55	0.06	0.05
PCO2, mmHg	70	68.4	1.73	40	40	1.47	22	22.2	2.63	1.94
HCO3-, mmol/L	ND	ND	1.8	ND	ND	1.35	ND	ND	2.37	1.84
Glu, mg/dL	200	199.1	1.65	100	99.3	1.65	50	49.5	1.35	1.55
Hb, g/dL	18	18	0.31	14	14	0.38	8	8	0.42	0.34
Hct, %	ND	ND	0.31	ND	ND	0.38	ND	ND	0.42	0.34

ND is Not Done, QC is quality control (target), CV is Coefficient of Variation, Na⁺ is sodium, K⁺ is potassium, Cl^- is chloride, PCO₂ is partial pressure of CO₂, HCO₃^- is bicarbonate, Glu is glucose, Hb is hemoglobin, and Hct is hematocrit.