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Blood gas tension refers to the partial pressure of gases in blood.^[1] There are several significant purposes for measuring gas tension;^[2] the most common gas tensions measured are oxygen tension^[3] (P_xO₂), the carbon dioxide tension^[3] (P_xCO₂) and carbon monoxide tension^[3] (P_xCO). The subscript x in each symbol represents the source of the gas being measured; "a" meaning arterial,^[3] "A" being alveolar,^[3] "v" being venous,^[3] "c" being capillary.^[3]

Oxygen tension

Arterial blood oxygen tension (normal)

P_aO₂ — Partial pressure of oxygen at sea level (765 mmHg) in arterial blood is between 75 mmHg and 100 mmHg.^[4]^[5]^[6]

Venous blood oxygen tension (normal)

P_vO₂ — Oxygen tension in venous blood at sea level is between 30 mmHg and 40 mmHg.^[6]^[7]

Carbon dioxide tension

Carbon dioxide is a by-product of food metabolism and in high amounts has toxic effects including: dyspnea, acidosis and altered consciousness.^[8]

Arterial blood carbon dioxide tension

P_aCO₂ — Partial pressure of carbon dioxide at sea level (765 mmHg) in arterial blood is between 35 mmHg and 45 mmHg.^[9]

Venous blood carbon dioxide tension

P_vCO₂ — Partial pressure of carbon dioxide at sea level in venous blood is between 40 mmHg and 50 mmHg.^[9]

Carbon monoxide tension

Arterial carbon monoxide tension (normal)

P_aCO — Partial pressure of CO at sea level (765 mmHg) in arterial blood is approximately 0.02. It can be slightly higher in smokers and people living in dense urban areas.

Significance

The partial pressure of gas in blood is significant because it is directly related to ventilation and oxygenation.^[10] When used alongside the pH balance of the blood, the PaCO₂ and HCO₃ (and Lactate) suggest to the health care practitioner which interventions, if any, should be made.^[10]^[11]

Equations

Oxygen content

The constant, 1.36, is the amount of oxygen (ml at 1 atmosphere) bound per gram of hemoglobin. The exact value of this constant varies from 1.34 to 1.39, depending on the reference and the way it is derived. The constant 0.0031 represents the amount of oxygen dissolved in plasma. The dissolved-oxygen term is generally small relative to the term for hemoglobin-bound oxygen, but becomes significant at very high P_aO₂ (as in a hyperbaric chamber) or in severe anemia.^[12]

Oxygen saturation

This is an estimation and does not account for differences in temperature, pH and concentrations of 2,3 DPG.^[13]

References

^ Severinghaus JW, Astrup P, Murray JF (1998). "Blood gas analysis and critical care medicine.". Am J Respir Crit Care Med 157 (4 Pt 2): S114–22. doi:10.1164/ajrccm.157.4.nhlb1-9. PMID 9563770.
^ Bendjelid K, Schütz N, Stotz M, Gerard I, Suter PM, Romand JA (2005). "Transcutaneous PCO2 monitoring in critically ill adults: clinical evaluation of a new sensor.". Crit Care Med 33 (10): 2203–6. doi:10.1097/01.ccm.0000181734.26070.26. PMID 16215371.
^ ^a ^b ^c ^d ^e ^f ^g Yildizdaş D, Yapicioğlu H, Yilmaz HL, Sertdemir Y (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. doi:10.1136/adc.2002.016261. PMC 1719810. PMID 14736638.
^ Shapiro BA (1995). "Temperature correction of blood gas values.". Respir Care Clin N Am 1 (1): 69–76. PMID 9390851.
^ Malatesha G, Singh NK, Bharija A, Rehani B, Goel A (2007). "Comparison of arterial and venous pH, bicarbonate, PCO2 and PO2 in initial emergency department assessment.". Emerg Med J 24 (8): 569–71. doi:10.1136/emj.2007.046979. PMC 2660085. PMID 17652681.
^ ^a ^b Chu YC, Chen CZ, Lee CH, Chen CW, Chang HY, Hsiue TR (2003). "Prediction of arterial blood gas values from venous blood gas values in patients with acute respiratory failure receiving mechanical ventilation.". J Formos Med Assoc 102 (8): 539–43. PMID 14569318.
^ Walkey AJ, Farber HW, O'Donnell C, Cabral H, Eagan JS, Philippides GJ (2010). "The accuracy of the central venous blood gas for acid-base monitoring.". J Intensive Care Med 25 (2): 104–10. doi:10.1177/0885066609356164. PMID 20018607.
^ Adrogué HJ, Rashad MN, Gorin AB, Yacoub J, Madias NE (1989). "Assessing acid-base status in circulatory failure. Differences between arterial and central venous blood.". N Engl J Med 320 (20): 1312–6. doi:10.1056/NEJM198905183202004. PMID 2535633.
^ ^a ^b Williams AJ (1998). "ABC of oxygen: assessing and interpreting arterial blood gases and acid-base balance.". BMJ 317 (7167): 1213–6. doi:10.1136/bmj.317.7167.1213. PMC 1114160. PMID 9794863.
^ ^a ^b Hansen JE (1989). "Arterial blood gases.". Clin Chest Med 10 (2): 227–37. PMID 2661120.
^ Tobin MJ (1988). "Respiratory monitoring in the intensive care unit.". Am Rev Respir Dis 138 (6): 1625–42. doi:10.1164/ajrccm/138.6.1625. PMID 3144222.
^ http://www-users.med.cornell.edu/~spon/picu/calc/oxycont.htm. Retrieved 7 October 2014. Missing or empty |title= (help)
^ Severinghaus, J. W. Simple, accurate equations for human blood O2 dissociation computations. J Appl Physiol. 46(3): 599-602. 1979.

UpToDate Contents

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1. 静脈血ガスおよび動脈血液ガスの代替 venous blood gases and other alternatives to arterial blood gases
2. 酸素供給と消費 oxygen delivery and consumption
3. 運動生理学 exercise physiology

English Journal

Risk stratification in patients with chronic heart failure based on metabolic-immunological, functional and haemodynamic parameters.

Herrmann R, Sandek A, von Haehling S, Doehner W, Schmidt HB, Anker SD, Rauchhaus M.SourceDepartment of Cardiology, Charite Medical School, Campus Virchow-Klinikum, Berlin, Germany.
International journal of cardiology.Int J Cardiol.2010 Nov 18. [Epub ahead of print]
BACKGROUND: A vast array of parameters has been proposed to predict mortality in chronic heart failure (CHF). Their applicability into clinical practice remains challenging due to economical and availability considerations.METHODS AND RESULTS: We studied serum uric acid, total cholesterol, and solub
PMID 21093941

Posttraumatic lung injury after pulmonary contusion and fat embolism: factors determining abnormal gas exchange.

Whelan DB, Byrick RJ, Mazer CD, Kay C, Richards RR, Zdero R, Schemitsch EH.SourceDivision of Orthopaedic Surgery, Department of Surgery, St. Michael's Hospital, Toronto, Ontario, Canada.
The Journal of trauma.J Trauma.2010 Sep;69(3):512-8.
BACKGROUND: The objective was to investigate changes in pulmonary blood flow after lung contusion and fat embolism.METHODS: Eighteen mongrel dogs were randomly assigned to three groups: fat embolism alone (n = 7); moderate unilateral pulmonary contusion followed by fat embolism (n = 6); and severe u
PMID 20838120

Japanese Journal

MS32-7 乳幼児期からの頻回の農薬曝露が誘因と考えられPVO2が指標となった化学物質過敏症の1例(アレルゲン・抗原と症例1,第59回日本アレルギー学会秋季学術大会)

水城まさみ,山田博之
アレルギー 58(8・9), 1301, 2009-09-30
NAID 110007675272

哺乳類ヘモグロビンの協同作用とボーア効果は協調して酸素の獲得と輸送を行っている : 規範タンパク質における新たな視点

張岩,今井清博,小林道頼
生物物理 47(3), 167-173, 2007-05-25
The slope of the oxygen equilibrium curve (OEC) of mammalian-hemoglobin (Hb) is maximized at S (oxygen saturation) value of 0.38, and the slope of the S vs. P/P_<50> (P is partial oxygen pressur …
NAID 110006273084

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