From the Guidelines
The standard procedure for drawing venous blood gases involves using a straight needle, discarding the first milliliter of blood, and using either no tourniquet or only a light tourniquet during collection, with blood drawn directly into a plastic tube containing sodium citrate (0.109 M) 1. When drawing venous blood gases, it is essential to follow a specific procedure to ensure accurate results and minimize complications.
- The use of a straight needle is preferred over a butterfly needle to avoid contact activation and hemolysis, as recommended by the majority of participants in a survey 1.
- Discarding the first milliliter of blood is advised to prevent contamination and ensure accurate results, especially in pediatric populations 1.
- The application of a tourniquet should be avoided or used with gentle pressure, only for locating the vein, to prevent blood cell activation and hemolysis 1.
- Blood should be drawn directly into a plastic tube containing sodium citrate (0.109 M) as an anticoagulant, rather than using a syringe and subsequently filling up the tubes, to avoid activation of coagulation and ensure accurate results 1.
- It is crucial to report pre-analytical conditions that may potentially influence test results, such as the presence of hemolysis or bilirubin 1. By following this procedure, healthcare professionals can ensure the quality of the samples and obtain accurate results for venous blood gas analysis, which provides valuable information about acid-base balance, electrolytes, and metabolic status.
From the Research
Standard Procedure for Drawing Venous Blood Gases
The standard procedure for drawing venous blood gases involves several key steps:
- Using a pre-heparinized syringe to avoid coagulation, as seen in studies 2, 3, 4
- Drawing venous blood from the dorsal or cubital vein (peripheral) 4
- Analyzing the blood samples promptly, ideally within 30 minutes, using an appropriate analyzer such as the EasyBloodGasTM analyzer 4
- Considering the reference intervals for venous blood gas measurements in healthy adults, which include:
- pH (7.29-7.43)
- Partial pressure of oxygen (25-70 mmHg)
- Partial pressure of carbon dioxide (35-59 mmHg)
- Bicarbonate (22-30 mmol/L)
- Electrolytes (sodium, potassium, chloride, and calcium) within specific ranges 4
- Being aware that venous blood gas analysis can be a valuable alternative to arterial blood gas analysis in certain situations, such as in hypotensive patients or for initial assessment and resuscitation in emergency and intensive care unit patients 2, 3
Key Considerations
- The use of pre-heparinized syringes is crucial to prevent coagulation and ensure accurate results 2, 3, 4
- The choice of vein and technique for drawing venous blood gases can impact the accuracy of the results 4
- Reference intervals for venous blood gas measurements can vary depending on the population and laboratory methods used 4
- Venous blood gas analysis can be a useful tool in certain clinical situations, but it is essential to consider the limitations and potential differences compared to arterial blood gas analysis 2, 3