What is the proper procedure for drawing a venous blood gas?

From the Guidelines

To draw a venous blood gas, it is recommended to use a straight needle, discard the first milliliters of blood, and use either no tourniquet or only a light tourniquet during the blood collection, as this minimizes potential contamination and ensures accurate results 1. When drawing a venous blood gas, several key steps should be followed to ensure the quality and accuracy of the sample.

• Use a straight needle if possible, as this can help reduce potential complications and improve the overall quality of the sample 1.
• Discard the first milliliters of blood to minimize contamination and ensure that the sample is representative of the patient's blood gas levels 1.
• Use either no tourniquet or only a light tourniquet during the blood collection, as this can help reduce hemolysis and ensure that the sample is not altered by the collection process 1.
• Take the blood directly into the blood drawing tube, and use a plastic blood tube containing sodium citrate (0.109 M) to prevent clotting and ensure accurate results 1.
• If CTI is used, add it to the blood tube prior to collection and keep the CTI concentration below 1.6 μM to minimize potential interference with the sample 1. It is also important to consider the type of blood draw device used, as this can influence the quality of the sample 1.
• Venipuncture using a needle and vacutainer tubes are the most commonly used methods for routine blood draw, but other methods such as butterfly needles or intravenous catheters may be used in certain situations 1.
• The choice of blood draw method should be based on factors such as patient characteristics, the type of tests to be performed, and the preference and experience of clinical staff 1.

From the Research

Proper Procedure for Drawing a Venous Blood Gas

The proper procedure for drawing a venous blood gas involves several steps:

• Using a pre-heparinized syringe to draw venous blood from the dorsal or cubital vein (peripheral) to avoid coagulation 2
• Drawing blood into a safePICO syringe for analysis on a blood gas analyzer, such as the ABL827 blood gas analyser 3
• Sending the samples directly to the laboratory for analysis, which can be completed in a short amount of time, such as 30 minutes 2
• Using a method such as the venous-to-arterial conversion method (v-TAC) to convert venous blood gas values to calculated values meant to resemble arterial values, if necessary 4, 5

Key Considerations

Some key considerations when drawing a venous blood gas include:

• The ease of draw and lower risk of complications compared to arterial blood gas analysis 2, 6
• The potential for venous blood gas analysis to be a useful alternative to arterial blood gas analysis in certain clinical settings 5, 3
• The importance of establishing reference intervals for venous blood gas measurements to ensure accurate interpretation of results 2, 3

Clinical Applications

Venous blood gas analysis has several clinical applications, including:

• Evaluation of blood gases in critically ill patients 4
• Detection of hypercapnia and hypoxemia 5
• Monitoring of patients with severe illness or acid-base disturbances 4, 5