Arterial or venous blood in a heparinised blood gas syringe,
or a micro-sample: collect one heparinised capillary tube .
Mix well. Transport to laboratory without delay.
|
Put patient label on the barrel of syringe, not the plunger.
For accurate results any bubbles or froth must be removed immediately before gentle mixing of the syringe (rolling for at least 20 seconds).
Samples (in plastic syringes transported at room temperature) are analysed promptly, but should be reported within 30 minutes to minimise the effect of oxygen diffusion. Ice does not improve reliability of results with plastic syringes.
Ref: Knowles, TP et al. Effects of syringe material, sample storage time and temperature on blood gases and oxygen saturation in arterial human blood samples. Resp. Care. 2006 51(7): 732-6
Capillary samples are very dependent on the quality of specimen collection, including the maintenance of anaerobic conditions during the procedure, to produce reliable results. pO2 is not reported on capillary specimens.
Cord Blood
0-2 years
2 yr - Adult
pH
arterial
7.10 - 7.40
7.35 - 7.45
7.35 - 7.45
pH
venous
7.22 - 7.44
7.30 - 7.40
7.30 - 7.40
pCO2 kPa
arterial
5.6 - 9.8
4.7 - 6.0
4.7 - 6.0
pCO2 kPa
venous
3.8 - 7.1
5.3 - 6.7
5.3 - 6.7
PO2 kPa
arterial
0.8 - 3.7
9.3 - 13.3
10.0 - 14.0
PO2 kPa
venous
2.2 - 5.3
Standard bicarb mmol/L
arterial
18 - 28
18 - 23
22 - 28
Standard bicarb mmol/L
venous
17 - 26
22 - 32
Base excess mmol/L
arterial and venous
-12 to +2
-5 to +5
-3 to +3
Oxygen saturation
arterial
95 - 100
Lactate mmol/L
arterial and venous
<6.1
<2.0
<2.0
-
1 kPa = 7.5 mmHg
-
also see Alveolar-Arterial Oxygen Gradient
-
also see Oxygen p50
-
Sodium, Potassium, Ionised Calcium, Chloride, Haemoglobin, Glucose and Lactate will also be measured if the sample is collected into a 1 mL blood gas syringe (at no extra cost)
Uncertainty of Measurement (Whole Blood):
|
pH |
0.03 |
|
pCO2 |
8% |
|
pO2 |
8% |
|
Chloride** |
3 mmol/L |
|
Glucose** |
8% |
|
Haemoglobin |
3 g/L at levels up to 100 g/L 3% at levels over 100 g/L |
|
Ionised Calcium** |
0.05 mmol/L |
|
Lactate** |
11% |
|
Potassium** |
0.2 mmol/L |
|
Sodium** |
3 mmol/L |
** for Serum/Plasma/Urine Uncertainty of Measurement please refer to the appropriate Serum/Plasma/Urine page
Venous blood collected into a heparinised syringe can be used in many clinical situations where pO2 and pCO2 are not required (e.g. DKA and other metabolic disturbances). The reference intervals are slightly different (for pH and pCO2 ) but this makes no significant difference to the interpretation of metabolic acid-base disturbances.