Do you know 7 factors that affect the results of arterial blood gas analysis?

Arterial blood gas analysis is one of the important laboratory testing methods for critically ill patients, and has important guiding significance for the formulation of diagnosis and treatment plans. In order to improve the quality control of arterial blood gas analysis and the accuracy of blood gas report results, domestic and foreign guidelines and literature have analyzed the factors affecting the variation of the pre-analysis of arterial blood gas analysis samples and put forward guiding suggestions. Then do you know the 7 factors that affect the results of arterial blood gas analysis. Friends who don’t understand can come to understand with the editor.

Arterial blood gas analysis

1. The influence of the material of the blood sampling device on the results of arterial blood gas analysis

There are two types of syringe materials, glass and plastic. The glass material can better prevent the penetration of gas. Therefore, a glass syringe with a well-sealed piston can ensure that the gas in the sample is basically unchanged within 2 hours.

2. The effect of heparin

Liquid heparin has a certain dilution effect on the sample. The indicators that will drop include electrolytes, HCO3-, CO2, hemoglobin, and pO2 and sO2 will rise in most cases because the partial pressure of oxygen in the heparin solution is about 150mmHg. In particular, the electrolyte changes are extremely obvious, because the electrode-potential difference method used by the blood gas analyzer measures the plasma rather than the electrolyte in the cells. Meilun

3. The impact of improper blood sampling

Blood gas values may change briefly due to hyperventilation, breath-holding, vomiting, or crying caused by tension. When the patient is emotionally unstable, the measured pH will increase and PaCO2 will decrease. Explain to the patient what operation will be performed in a pleasant and relaxing way.

4. The effect of bubbles

If air bubbles are mixed during specimen collection, they should be removed immediately. If the time is too long, errors may occur in the measurement results, specifically as pH and PaO2 increase, and PaCO2 decrease.

5. Effects of specimen hemolysis

During the specimen submission process, if hemolysis or coagulation occurs, it will directly affect the reliability of blood gas analysis results. The clotted specimen can block the tubing system of the instrument. If the blood is dissolved, the pO2 and pCO2 in the blood gas result will increase, and the pH will decrease.

6. The specimen has no effect of shaking

Whether the specimen is fully shaken during analysis will also affect the results of blood gas detection. This is mainly because there is heparin in the dead space at the front end of the empty needle syringe, and the pH of heparin is 6.56, which is not completely mixed with the blood. Melon can directly cause the measurement result to be acidic.

7. The influence of specimen placement time

Specimens should generally be tested in time. If the analysis cannot be completed in time, they should not be placed in room temperature (below 25 degrees Celsius) for no more than 15 minutes. The determination cannot be completed within 15 minutes and should be stored in an ice-water mixture (about 4 degrees Celsius), but not more than 30 minutes. Otherwise, the measured arterial blood gas analysis results will be biased, that is, the pH and pO2 in the measured blood gas results will decrease, and the pCO2 will increase.=