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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] Blood gas tests (such as arterial blood gas tests) measure these partial pressures.

Oxygen tension

Arterial blood oxygen tension (normal)

P_aO₂ – Partial pressure of oxygen at sea level (160 mmHg in the atmosphere) 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 P_aCO₂ and HCO₃ (and Lactate) suggest to the health care practitioner which interventions, if any, should be made.^[10]^[11]

Equations

Oxygen content

C_{a}{\ce {O2}}=1.36\cdot {\ce {Hgb}}\cdot {\frac {S_{a}{\ce {O2}}}{100}}+0.0031\cdot P_{a}{\ce {O2}}

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

{\ce {SO2}}=\left({\frac {23,400}{p{\ce {O2}}^{3}+150p{\ce {O2}}}}+1\right)^{-1}

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.
^ "Oxygen Content". Retrieved October 7, 2014.
^ Severinghaus, J. W. (1979). "Simple, accurate equations for human blood O₂ dissociation computations" (PDF). J Appl Physiol. 46 (3): 599–602. PMID 35496.

UpToDate Contents

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1. 低酸素血症の酸素供給およびメカニズムoxygenation and mechanisms of hypoxemia [show details]
2. 動脈血液ガスarterial blood gases [show details]
3. 酸素供給と消費oxygen delivery and consumption [show details]
4. 酸素毒性oxygen toxicity [show details]
5. 高二酸化炭素血症の発症機序、原因、および影響mechanisms causes and effects of hypercapnia [show details]

English Journal

Hyperoxygenated Hydrogen-Rich Solution Suppresses Lung Injury Induced by Hemorrhagic Shock in Rats.

Meng X, Xu H, Dang Y, Fan Y, Lv M, Sang H, Xu L.
The Journal of surgical research. 2019 Jul;239()103-114.
Hemorrhagic shock could induce acute lung injury (ALI), which is associated with cell hypoxia, lung tissue inflammation, free radical damage, and excessive cell apoptosis. Our previous studies demonstrated that hyperoxygenated solution could alleviate cell hypoxia. Furthermore, hydrogen-rich solutio
PMID 30825755

Posttreatment With the Fatty Acid Amide Hydrolase Inhibitor URB937 Ameliorates One-Lung Ventilation-Induced Lung Injury in a Rabbit Model.

Yin H, Li X, Xia R, Yi M, Cheng Y, Wu Y, Ke B, Wang R.
The Journal of surgical research. 2019 Jul;239()83-91.
One-lung ventilation (OLV)-induced inflammation is a risk factor for acute lung injury that is responsible for 20% of postoperative pulmonary complications after lung resection. Inflammation is an important trigger for acute lung injury. Fatty acid amide hydrolase (FAAH) is the major enzyme that deg
PMID 30822695

Intratumoral Injection of Hypertonic Glucose in Treating Refractory Pneumothorax Caused by Microwave Ablation: a Preliminary Study.

Wang D, Li X, Yu W.
Cardiovascular and interventional radiology. 2019 Jun;42(6)915-919.
The purpose of this technical report is to describe the technique of intratumoral injection of hypertonic glucose combined with low-negative pressure drainage to treat refractory pneumothorax (RP) after microwave ablation (MWA) of lung tumors. Between September 2016 and May 2018, four patients who d
PMID 30843091

Japanese Journal

Low Levels of PaO₂ after Long-term Noninvasive Ventilation are a Poor Prognostic Factor in Patients with Restrictive Thoracic Disease

Chihara Yuichi,Tsuboi Tomomasa,Sumi Kensuke,Sato Atsuo,Oga Toru,Chin Kazuo
Internal Medicine 58(9), 1243-1250, 2019-05-01
Objective: The effects of partial pressure of arterial oxygen (PaO₂) after introducing long-term noninvasive ventilation (NIV) on the prognosis of patients with restrictive thoracic disease and chroni …
NAID 120006634658

Case Report : Usefulness of monitoring the oxygen reserve index in the pediatric intensive care unit

Shimizu Naoki,Ogiwara Shigetoshi,Saito Osamu
千葉医学 = Chiba medical journal 95(1), 7-9, 2019-02
… Pulse oximetry does not indicate downward trends in arterial partial pressure（PaO2） until the percutaneous arterial oxygen saturation（SpO2）begins to fall. …
NAID 120006559329

SaO₂とPaO₂で「動脈血中の酸素がどのくらい減っているか」をみる (特集これ以上やさしく書けない! 低酸素と酸素投与) -- (酸素化の測定)

Expert nurse = エキスパートナース 34(11), 35-39, 2018-09
NAID 40021662081

「pO2」

　　[★]

関: 酸素分圧

paO2
pAO2

「PAO2」

　　[★]

同: alveolar partial pressure of oxygen

[pmid9563770-1] 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.

[pmid16215371-2] 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.

[pmid14736638-3] ^ ^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.

[pmid9390851-4] Shapiro BA (1995). "Temperature correction of blood gas values". Respir Care Clin N Am. 1 (1): 69–76. PMID 9390851.

[pmid17652681-5] 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.

[pmid14569318-6] 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.

[pmid20018607-7] 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.

[pmid2535633-8] 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.

[pmid9794863-9] 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.

[pmid2661120-10] Hansen JE (1989). "Arterial blood gases". Clin Chest Med. 10 (2): 227–37. PMID 2661120.

[pmid3144222-11] 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.

[12] "Oxygen Content". Retrieved October 7, 2014.

[13] Severinghaus, J. W. (1979). "Simple, accurate equations for human blood O₂ dissociation computations" (PDF). J Appl Physiol. 46 (3): 599–602. PMID 35496.

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