Total carbon dioxide (TCO2)

The total amount of carbon dioxide refers to the total content of all carbon dioxide (CO2) present in various forms in plasma, the majority of which (95%) is in bound form. The TCO2 measurement can be obtained indirectly by the blood gas acid-base analyzer, which is simple and reliable. In the past, the traditional method was based on the volume and pressure method designed by Vansiyke. It can also be used if necessary, and the analysis results are also reliable. There are also photometric methods, Conway micro-diffusion method and enzymatic method. Basic Information Specialist classification: cardiovascular examination classification: blood examination Applicable gender: whether men and women apply fasting: not fasting Analysis results: Below normal: Reduced in metabolic acidosis (uremic, shock, diabetic ketoacidosis, severe diarrhea and dehydration). Normal value: Cord blood: 14-22mmol/L Newborn: 17-24mmol/L Infants, children: 20-28mmol/L Adult: 23-31mmol/L Above normal: Above normal, it is seen in metabolic alkalosis. negative: Positive: Tips: The patient should be in a quiet, stable state of breathing, sitting and lying, sleeping and waking, after exercise and after eating, will produce different results. Normal value Serum determination: Cord blood 14 ~ 22mmol / L (14 ~ 22mEq / L). Newborns 17 ~ 24mmol / L (17 ~ 24mEq / L). Infants and children 20 to 28 mmol/L (20 to 28 mEq/L). Adult 23 ~ 31mmol / L (23 ~ 31mEq / L). Clinical significance Abnormal results: Increase: 1 respiratory acidosis (emphysema, pulmonary fibrosis, respiratory muscle paralysis, bronchiectasis, pneumothorax, airway obstruction). 2 metabolic alkalosis (vomiting, adrenal hyperfunction, potassium deficiency and excessive basic drugs). reduce: 1 metabolic acidosis (uremia, shock, diabetic ketoacidosis, severe diarrhea and dehydration). 2 respiratory alkalosis (breathing center excitement and rapid breathing, etc.). Need to check the crowd: Patients with severe diarrhea, dehydration, and vomiting symptoms. Low results may be diseases: high results of uremia may be diseases: respiratory acidosis precautions Note when checking: (1) The f value must be checked accurately when calculating. The sample dosage is different (2ml or 0.2ml), the total volume of the reaction solution is different (3.5ml or 2ml), and the gas volume is fixed at different positions (2ml or 0.5ml). The corresponding f value. (2) When the sample is small, 0.2 ml of plasma can be used instead. The operation was basically the same, but 1.6 ml of distilled water and 0.2 ml of a lactic acid solution were introduced, so that the total amount of the reaction liquid was S = 2 ml, and a = 0.5 ml. The corresponding f values ​​under the 0.2 ml sample of Table 1 were used instead. Pre-inspection requirements: (1) The whole blood can also be used for the determination of CO2 content, and the result is about 15% lower than that of plasma. (2) The blood should be measured as soon as possible after extraction. (3) The patient should be in a state of quiet and stable breathing, and the pain of the patient should be minimized during the puncture. Sitting and lying, after sleep and waking, after exercise and after eating will produce different results. Inspection process Bicarbonate in plasma (clear) reacts with phosphoenolpyruvate (PEP) under the catalysis of phosphoenolpyruvate hydroxylase (PEPC) to form oxaloacetate and phosphoenolpyruvate and malate dehydrogenation The enzyme (MDH) reacts to form malic acid while oxidizing NADH to NAD+; the decrease in absorbance at 340 nm is proportional to the HCO3- content in the sample. Not suitable for the crowd Have a coagulopathy such as hemophilia. Adverse reactions and risks 1, subcutaneous hemorrhage: due to pressing time less than 5 minutes or blood draw technology is not enough, etc. can cause subcutaneous bleeding. 2, discomfort: the puncture site may appear pain, swelling, tenderness, subcutaneous ecchymosis visible to the naked eye.

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