From the Guidelines
A cardiology team would be reluctant to do a blood gas venous because it does not provide a reliable assessment of arterial oxygen levels, which is crucial in managing cardiac patients, especially those with suspected pulmonary embolism (PE) or other conditions that may lead to hypoxemia or respiratory failure 1.
When diagnosing and managing acute pulmonary embolism, as outlined in the 2019 ESC guidelines, the focus is on quickly and accurately assessing the patient's condition to initiate appropriate treatment, such as anticoagulation or thrombolysis 1. The guidelines emphasize the use of bedside echocardiography, emergency CTPA, or validated diagnostic criteria for diagnosis, highlighting the importance of precise and direct assessments of cardiac and respiratory function.
In the context of cardiac care, particularly for conditions like pulmonary embolism, the preference for arterial blood gas (ABG) over venous blood gas (VBG) stems from the need for accurate oxygenation status and arterial carbon dioxide levels, which are critical for guiding treatment decisions, such as the need for oxygen therapy or mechanical ventilation 1.
Moreover, the British Thoracic Society guideline for bronchiectasis in adults suggests the use of pulse oximetry to screen for patients who may need blood gas analysis to detect respiratory failure, implying that when respiratory function is a concern, as it often is in cardiac patients, more direct measures of oxygenation are preferred 1.
Given the potential for venous blood gases to provide misleading information about the patient's oxygenation status and the critical nature of accurate assessments in cardiac care, cardiology teams are likely to prioritize arterial blood gases or other more direct diagnostic tools when managing patients with suspected or confirmed cardiac conditions that may impact respiratory function or oxygen delivery 1.
From the Research
Reluctance to Perform Venous Blood Gas Analysis
- A cardiology team may be reluctant to perform a venous blood gas analysis due to its limitations in assessing oxygenation, as stated in the study 2.
- Venous blood gas analysis is not able to assess oxygenation, and pulse oximetry is a non-invasive alternative for arterial blood gas sampling, as mentioned in the study 2.
- The use of a venous blood gas to assess a patient's ventilation is limited, whereas it can be used to diagnose carbomonoxide intoxication or methaemoglobinaemia, as noted in the study 2.
Bleeding Risks and Anticoagulant Therapy
- The combination of antiplatelet and anticoagulant therapies, such as aspirin, clopidogrel, and warfarin, can increase the risk of bleeding events, as reported in the study 3.
- The study 3 found that four of 12 studies reported no increased risk of major bleeding events, while the other eight studies reported a 3- to 6-fold increase in bleeding events with triple antithrombotic therapy.
- The use of anticoagulant therapies, such as warfarin, rivaroxaban, apixaban, edoxaban, and dabigatran, can also increase the risk of bleeding, as discussed in the study 4.
Antiplatelet Therapy and Coagulation Activation
- The study 5 found that clopidogrel does not suppress blood markers of coagulation activation in aspirin-treated patients with non-ST-elevation acute coronary syndromes.
- The combination of aspirin and clopidogrel has a potent protective effect against adverse vascular events, but the combination of these two agents has an even stronger antiplatelet effect, as noted in the study 6.
- The study 6 also discussed the importance of antiplatelet therapy in the management of patients with acute coronary syndromes and generally high-risk patients with atherothrombosis.