Blood gas analysis
In medicine and physiology, blood gas analysis is "measurement of oxygen and carbon dioxide in the blood."[1]
Venous blood
One study concluded "The mean difference between arterial and venous values of pH was 0.03 pH units."[2] If the pCO2 of of venous blood is less than 45 mm Hg, then the arterial pCO2 is very likely less than 50 mm hg.[3] Regarding pO2, venous pO2 is much lower.[4]
Artifacts in measurement
Delay in analysis after collection of blood
Delays of 30 to 60 minutes may not matter if the specimens are stored on ice.[5]
Delay lowers the pO2 unless air bubbles or froth are present in which case delay raises the pO2.[6][7]
Exposure of blood to room air
Exposure to room air, either through not sealing the specimen or not removing air bubbles, can moves pO2 towards the pO2 of the ambient air (150 mm Hg at sea level).[8] Since the pO2 of blood is usually less than 150, the effect of air it to raise the pO2.
References
- ↑ Anonymous (2024), Blood gas analysis (English). Medical Subject Headings. U.S. National Library of Medicine.
- ↑ Middleton P, Kelly AM, Brown J, Robertson M (August 2006). "Agreement between arterial and central venous values for pH, bicarbonate, base excess, and lactate". Emerg Med J 23 (8): 622–4. DOI:10.1136/emj.2006.035915. PMID 16858095. Research Blogging.
- ↑ Kelly AM, Kerr D, Middleton P (May 2005). "Validation of venous pCO2 to screen for arterial hypercarbia in patients with chronic obstructive airways disease". J Emerg Med 28 (4): 377–9. DOI:10.1016/j.jemermed.2004.10.017. PMID 15837016. Research Blogging.
- ↑ Yildizdaş D, Yapicioğlu H, Yilmaz HL, Sertdemir Y (February 2004). "Correlation of simultaneously obtained capillary, venous, and arterial blood gases of patients in a paediatric intensive care unit". Arch. Dis. Child. 89 (2): 176–80. PMID 14736638. PMC 1719810. [e]
- ↑ Woolley A, Hickling K (March 2003). "Errors in measuring blood gases in the intensive care unit: effect of delay in estimation". J Crit Care 18 (1): 31–7. DOI:10.1053/jcrc.2003.YJCRC7. PMID 12640611. Research Blogging.
- ↑ Biswas CK, Ramos JM, Agroyannis B, Kerr DN (March 1982). "Blood gas analysis: effect of air bubbles in syringe and delay in estimation". Br Med J (Clin Res Ed) 284 (6320): 923–7. PMID 6802352. PMC 1496510. [e]
- ↑ Harsten A, Berg B, Inerot S, Muth L (July 1988). "Importance of correct handling of samples for the results of blood gas analysis". Acta Anaesthesiol Scand 32 (5): 365–8. PMID 3414345. [e]
- ↑ Madiedo G, Sciacca R, Hause L (September 1980). "Air bubbles and temperature effect on blood gas analysis". J. Clin. Pathol. 33 (9): 864–7. PMID 7430400. PMC 1146247. [e]