Pulmonary embolism arterial blood gas analysis
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Editor(s)-In-Chief: The APEX Trial Investigators, C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]
Synonyms and Keywords: ABG
Overview
Routine laboratory tests including arterial blood gas analysis are non-specific in patients with acute pulmonary embolism; however, in cases of suspected PE they may be ordered to rule-out secondary causes. Hypoxemia, hypocapnia, increased A-a gradient and respiratory alkalosis are common findings that may be observed in patients with PE.
Arterial blood gas
Findings
- In patients with pulmonary embolism, arterial blood gas analysis may reveal:[1]
- Hypoxemia,
- Hypocapnia,
- Increased alveolar-arterial oxygen difference (P(A-a)O2 gradient) and
- Respiratory alkalosis.
- However, the above mentioned ABG findings are not exclusive for the diagnosis PE. Some variations include:
- Hypercapnia in cases of massive PE secondary to circulatory collapse.
- Normal PaO2 (partial pressure of oxygen in arterial blood) levels as demonstrated by majority of patients.[2]
- Normal alveolar-arterial oxygen gradient may be observed in ~6% of patients.
Sensitivity and Specificity
- In patients with suspected PE, Rodger et al, demonstrated that ABG analysis did not have sufficient negative predictive value, specificity, or likelihood ratios to be considered useful in the management these patients.[3] Similar findings were observed by the PIOPED II investigators.[4]
Pulse Oximetry
The use of pulse oximetry in the diagnosis of pulmonary embolism is restricted. In 2003, Kline et al, demonstrated that a room-air pulse oximetry reading of ≥ 95% at diagnosis was associated with a significantly lower probability of in-hospital complications from pulmonary embolism and hence may be used as a prognostic marker.[5]
References
- ↑ Cvitanic O, Marino PL (1989). "Improved use of arterial blood gas analysis in suspected pulmonary embolism". Chest. 95 (1): 48–51. PMID 2491801. Retrieved 2012-04-30. Unknown parameter
|month=ignored (help) - ↑ Stein PD, Terrin ML, Hales CA, Palevsky HI, Saltzman HA, Thompson BT, Weg JG (1991). "Clinical, laboratory, roentgenographic, and electrocardiographic findings in patients with acute pulmonary embolism and no pre-existing cardiac or pulmonary disease". Chest. 100 (3): 598–603. PMID 1909617. Retrieved 2012-04-30. Unknown parameter
|month=ignored (help) - ↑ Rodger MA, Carrier M, Jones GN, Rasuli P, Raymond F, Djunaedi H, Wells PS (2000). "Diagnostic value of arterial blood gas measurement in suspected pulmonary embolism". American Journal of Respiratory and Critical Care Medicine. 162 (6): 2105–8. PMID 11112122. Retrieved 2012-04-30. Unknown parameter
|month=ignored (help) - ↑ Stein PD, Woodard PK, Weg JG, Wakefield TW, Tapson VF, Sostman HD, Sos TA, Quinn DA, Leeper KV, Hull RD, Hales CA, Gottschalk A, Goodman LR, Fowler SE, Buckley JD (2006). "Diagnostic pathways in acute pulmonary embolism: recommendations of the PIOPED II investigators". The American Journal of Medicine. 119 (12): 1048–55. doi:10.1016/j.amjmed.2006.05.060. PMID 17145249. Retrieved 2012-04-30. Unknown parameter
|month=ignored (help) - ↑ Kline JA, Hernandez-Nino J, Newgard CD, Cowles DN, Jackson RE, Courtney DM (2003). "Use of pulse oximetry to predict in-hospital complications in normotensive patients with pulmonary embolism". The American Journal of Medicine. 115 (3): 203–8. PMID 12935827. Retrieved 2012-05-01. Unknown parameter
|month=ignored (help)