Preparation of the patient, blood collection
Sampling is an important prerequisite for an objective assessment of the patient's health. Based on generally accepted principles, we have prepared a brief methodology of the sampling procedure:
Venous blood collection
Blood for routine testing is to be collected on an empty stomach in the morning, preferably between 7.00 am – 8.00am, after 8 – 12 hours of night-time fasting. The patient may drink a small amount of clean water (2 dL/ 0.85 US cups of water). Blood should be collected before the potential use of medication. Collections for special tests in which diurnal or other rhythm is observed are to be performed according to specified criteria.
Blood is most frequently collected from the peripheral vein in the elbow hole, preferably not from the shoulder where the infusion is delivered. The patient should lie down. If blood is collected while the patient is sitting, the patient should remain seated for at least 15 minutes prior to collection. The spot about 10 centimetres above the spot of blood collecting is gently pressed, never longer than for 1 minute. The skin is disinfected prior to injection (70% Isopropanol, 70-80% Ethanol). After the disinfection the spot should be allowed to dry since alcohol may cause Haemolysis.
Blood is collected by means of a needle whose diameter corresponds to the diameter of the vein. A needle with a diameter wider than 1 mm may cause the release of vascular fragments that may affect the Haemostasis parameters. High pressure with Haemolysis and Thrombocyte activation is created in a needle with a diameter of less than 0.7 mm. The speed of collecting blood into the vacuum tubes is given by the vacuum; if collected into other tubes, it should be performed slowly in order to avoid cell damage and Haemolysis. Under no circumstances may blood be collected by a large syringe, from which it is then pressurized into other tubes. It is important for the tube to be filled up to the line. If blood is collected into multiple tubes, it is advisable to follow the following order:
- Tube without additives (haemoculture)
- Haemocoagulation tube
- Serum tube without gel barrier
- Serum tube with gel barrier
- Plasma analysis tube
- EDTA tube
- Glucose test tube
- Other tubes
Immediately after collecting blood, it is necessary to mix the specimen with the additives by slowly tilting the tube – a Haemocoagulation tube 3 – 5 times, the other tubes 5 – 1 0 times. Never shake vigorously. The blood for Glucose test should be centrifuged within 1 hour. If this is not possible, the blood should be collected into a tube with Glycolysis inhibitors (NaF / Potassium Oxalate, NaF / EDTA).
Capillary blood collection
Capillary blood collection is applied for Glucose determination within self-monitoring or Glucose profile and for ABR parameters determination. Blood is collected from the finger or ear lobe after their hypereremization and disinfection.
Capillary blood collection test: After pricking a sterile lancet, the necessary amount of blood is collected into a tube with Sodium Fluoride/Potassium Oxalate content that acts as a Glycolysis inhibitor thus providing a stable Glucose level in the sample taken within up to 24 hours.
ABR collection: Blood is collected into a capillary containing dry Li-Heparin and a metal body, and after collection, it must be well mixed and immediately capped. No air bubbles are to be present in the sample. The sample should be transported to the testing laboratory on frozen ice packs and must be processed no later than 1 hour after collecting.
Artery blood collection
Artery collection is used In order to determine ABR parameters; blood is collected from the artery into a tube containing Lithium Heparin as an anticoagulant. No air bubbles are to be present in the sample. Immediately after collecting the tube should be sealed hermetically and transported to the testing laboratory on frozen ice packs as soon as possible.