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Blood analysis is the examination of a blood sample in a laboratory to determine its physical and chemical properties. Blood analysis is typically performed on a sample of blood drawn from a vein in the arm, finger, or earlobe; bone marrow blood cells may also be examined in some cases. Hundreds of haematological tests as well as hundreds of procedures have been developed, and many of them can be performed on a single blood sample at the same time using various instruments such as autoanalyzers.
Properties of Blood
Plasma and blood cells make up blood. Blood cells—erythrocytes (red blood cells), leukocytes (white blood cells), and thrombocytes (platelets)—are suspended in plasma along with other particles. Plasma is a clear straw-colored fluid that accounts for more than half of blood volume. It differs from serum in that fibrinogen, a soluble protein normally found in plasma, has been converted to fibrin, an insoluble clotting protein, and fibrin and other clotting proteins have been removed.
When plasma or whole blood is allowed to clot, serum is formed. To separate plasma or serum from blood samples, centrifugation can be used. To keep all the contents in suspension, tests to measure the concentration of substances in the blood may use plasma, serum, or whole blood that has been anticoagulated.
Measurable Properties of Blood
Many tests are designed to determine the number of erythrocytes and leukocytes in the blood, as well as their volume, sedimentation rate, and haemoglobin concentration (blood count). Furthermore, certain tests are used to categorise blood based on specific red blood cell antigens, or blood groups. Other tests reveal information about the shape and structure of blood cells, haemoglobin, and other blood proteins. Blood can also be analysed to determine the activity of different enzymes, or it can be analysed to determine the protein catalysts that are either associated with blood cells or found free in blood plasma.
What is Blood Gas Analysis?
A blood gas test determines the concentrations of oxygen and carbon dioxide in the blood. It can also be used to determine the blood's pH, or how acidic it is. The procedure is also known as a blood gas analysis or an arterial blood gas (ABG) test.
Your red blood cells are responsible for transporting oxygen and carbon dioxide throughout your body. These are referred to as blood gases.
As blood flows through your lungs, oxygen enters the blood and carbon dioxide exits the blood into the lungs. The blood gas test can tell you how well your lungs move oxygen into your blood and remove carbon dioxide from it.
Risks of a Blood Gas Test
A blood gas test is considered a low-risk procedure because it does not require a large sample of blood.
However, you should always inform your doctor if you have any existing medical conditions that may cause you to bleed more than usual. You should also inform them if you are taking any over-the-counter or prescription medications that may affect your bleeding, such as blood thinners.
The following are possible side effects of the blood gas test:
bruising or bleeding at the point of the puncture
faint feeling of blood accumulating beneath the skin infection at the puncture site
Inform your doctor if you experience any unexpected or long-lasting side effects.
Blood Gas Analyzer
A glass electrode is used in blood gas analyzers to measure pH, and a membrane-covered glass electrode is used to measure pCO2 (Stow-Severinghaus electrode). ctH+Ecf is calculated from pH, pCO2, and cHb (concentration of haemoglobin) using the Van Slyke equation, a titration curve model.
Is a Venous Blood Gas Analysis Comparable to an Arterial Blood Gas?
Except for O2 and CO2, the values on a VBG and ABG are comparable (arterial and venous values are NOT significantly different for practical purposes).
According to a 2014 meta-analysis and related papers:
For adult pH estimations, VBG analysis outperforms ABG analysis.
The pH of the peripheral venous system is only from 0.02 to 0.04 which is lower than the arterial pH.
The concentration of HCO3 in the peripheral venous system is approximately 1 to 2 meq/L higher than in the arterial system.
However, the levels of PCO2 in the venous and arterial circulations are not comparable.
The bias for venous PCO2 has an unacceptably wide 95 percent prediction interval, ranging from -10.7 mmHg to +2.4 mmHg.
PO2 levels in the venous and arterial circulations are also not comparable. The arterial PO2 is typically 36.9 mmHg which is higher than the venous (with a ninety-five percent confidence interval ranging from 27.2 to 46.6 mmHg).
What is Arterial Blood Gas Analysis?
Arterial blood gases (ABGs) or blood arterial gas tests are blood tests that are taken from an arterial blood supply to provide information about ventilation, gas exchange, and acid-base status. It is important to note that this is not the same as venous blood gases, which are used when arterial supply is unavailable or unreliable due to disease. The line is typically inserted in the radial artery at the wrist, but it is also occasionally used in the femoral artery in the groyne. This is important to keep in mind when moving and handling a patient because it is easy to catch a line on an object or clothing and must be handled with caution.
Hematology analyzers (also known as haematology analysers in British English) are devices that count and identify blood cells at high speeds and with high accuracy. Under a microscope, laboratory technicians counted each individual blood cell in the 1950s.
Blood and Urine Test
A urine test examines the various components of urine, a waste product produced by the kidneys. Although it is not always possible during your initial examination, a urine test can assist your doctor in diagnosing stroke-related conditions such as blood clots, kidney disease, diabetes, and other metabolic diseases.