Blood collection
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As blood , blood collection or effusion (to latin effusio , outpouring ) is in the process of the medicine referred to in which a blood sample is obtained from the body. Usually, a blood vessel is punctured with a cannula . For small amounts of blood (e.g. when measuring blood sugar ), the superficial scratching of a part of the body with good blood supply (such as the earlobe or fingertip in humans) is sufficient to obtain capillary blood. To obtain larger amounts of blood, the puncture of veins is easier and usually without complications. For this purpose, superficial veins are used, which are also used for intravenous injections. Arteries are also punctured for special examinations such as blood gas analyzes .
Goal setting
The blood sample can be used to answer a wide range of medical questions.
The blood count provides information about the different types of cells ; a differential blood count shows the distribution of white blood cells ( leukocytes ) more precisely. The volume fraction of red blood cells in the blood is determined by means of the hematocrit . The concentration of important electrolytes such as sodium , potassium , calcium , magnesium , chloride and hydrogen carbonate is determined in the serum .
In the case of inflammation, the C-reactive protein and the rate of sedimentation can provide diagnostic information. A wide range of infectious diseases (e.g. hepatitis B or HIV ) can also be detected indirectly through serological blood tests or directly through molecular biological methods. In addition, some pathogens (e.g. Babesia ) can be shown directly in the blood smear using special staining techniques. Some bacteria can be grown from the blood during a bacteriological examination ( blood culture ). A number of non-infectious diseases can also be detected by detecting specific antibodies or measuring the activity of certain enzymes .
The blood sample is also carried out when it comes to a blood donation ; be it for personal use before risky operations or for external use. Different blood group systems are determined. Arterial blood is required as part of a blood gas analysis .
Delegation to non-medical, qualified personnel
Transferring injections , infusions and blood withdrawals to non-medical staff falls under the employer's right to direct or give instructions. In health care, the doctor does not need to provide all services personally, but can transfer tasks to sufficiently qualified employees ( Section 28 (1) SGB V ), also called vertical division of labor, which is not precisely regulated by law and is quite controversial, also to what extent medical tasks may be delegated. The Federal Court of Justice (BGH) passed the following judgment on June 24, 1975: "The use of non-medical auxiliaries is an integral part of modern medicine, and in particular of today's clinic system. It is also inevitable that these auxiliaries have a high degree of responsibility. .. A personal intervention of the doctor is basically only to be demanded, where the respective activity requires the doctor's own knowledge and skills. "
This means that, especially in academic teaching hospitals and university hospitals is to be expected that Assistants and PJ - students take doctors do blood sampling. But also in other clinics there are increasingly specially trained nursing staff or medical assistants and medical assistants who take on this important routine task.
Place of blood collection
People
If only a very small amount of blood is required, the fingertip on the side or the earlobe can be pierced with a lancet . If used correctly, this technique is associated with little pain and is sufficient to obtain individual drops of capillary blood. In diabetics it is used to determine the blood sugar level , in blood donors to determine the hemoglobin level .
In most cases, venous blood is taken from a vein in the area of the crook of the elbow or the back of the hand, less often on the forearm. If no suitable vein can be found in these areas, the foot is occasionally used as an alternative, but pricking the foot veins is generally quite painful. Another alternative for patients with very poor vein conditions is the possibility of taking blood from the deep inguinal vein ( femoral vein ) or a jugular vein ( external jugular vein ). In infants, blood is occasionally drawn from a superficial cephalic vein.
Taking a blood sample from an artery is common for performing blood gas analysis during operations and in intensive care medicine. In most cases, arterial blood is drawn from the radial artery on the wrist or the femoral artery in the groin. Other, less frequently used alternatives are the arteries on the foot (a. Dorsalis pedis on the back of the foot or a. Tibialis posterior below the inner ankle), the arteria brachialis in the elbow or the arteria axillaris in the armpit. In general, the puncture of an artery is very painful compared to a venous puncture; in pain-sensitive patients, the puncture site can be numbed using local anesthesia .
Animals
The jugular vein ( external jugular vein ) is usually used in horses . Occasionally a superficial vein of the lateral abdominal wall ( Vena thoracica superficialis ) is punctured. Arterial blood is usually obtained from a facial artery ( Arteria transversa faciei ).
The jugular vein ( external jugular vein ) is also used in cattle , sheep and goats . Taking blood from a vein on the underside of the tail ( vena caudalis mediana ) has also proven itself in cattle. In dairy cows, puncturing the so-called “milk vein” ( vena epigastrica cranialis superficialis ) is also quite easy. When puncturing the milk vein, however, it should be ensured that the animal does not subsequently lie down on a contaminated surface. Contamination of the wound can lead to painful inflammation or edema. In cattle, arterial blood is usually obtained from one of the ear arteries. In smaller ruminants, puncture of the femoral artery or the dorsal metatarsal arteries (branches of the dorsal artery pedis ) is recommended .
In domestic dogs , cats and ferrets , either a forearm vein ( vena cephalica ) or a lower leg vein ( vena saphena lateralis or vena saphena medialis ) is used. The jugular vein is rarely punctured.
In pigs , due to the thick rind, a targeted puncture of the veins is more difficult, as the veins are not visible due to congestion. The ear veins ( venae auriculares ) can be blocked for smaller amounts of blood . For larger amounts of blood, a blind puncture of the external jugular vein, brachiocephalic vein and cava cranial vein is possible. It is also possible to puncture the enlarged vein plexus behind the eye ( ophthalmic sinus ) in pigs .
Since the veins in small mammals are already quite small, drawing blood is much more difficult here. In rabbits , guinea pigs and chinchillas , the lateral saphena vein is most suitable , and blood can also be obtained from the ear veins or the jugular vein . In the case of smaller animals, anesthesia must first be carried out and the jugular vein can then be exposed or the plexus plexus ( plexus ophthalmicus ) or the heart can be punctured . In laboratory animal science, the tip of the tail amputation is still legally permitted.
In larger birds , the upper arm vein ( vena basilica ), forearm vein ( vena ulnaris ) or the left jugular vein can be punctured. In the case of small birds, a claw is often trimmed and the drop of blood that emerges is obtained. In birds without sex dimorphism , blood is also used to determine sex. The blood attached to a plucked pen on the quill is sufficient to determine gender .
Blood sampling using blood-sucking insects
A modern, emerging method is using specially cultivated, blood-sucking bedbugs to draw blood in more difficult cases, e.g. B. zoo animals. The bugs suck up on the “test person” within a short time, the blood can then be easily drawn out of them with a syringe and examined. This method is e.g. B. very successful with predators, where a conventional blood collection can otherwise only be carried out extremely laboriously and stressful and under anesthesia. The sting is usually not noticed by the animal because of the anesthetic substances that the bug injects when stung. Aids such as twine, which are attached to the blood-sucking insect, can be used for finding or catching. Even in elephants with their thick skin, blood can be drawn by applying bugs for a few minutes. Bats can take a blood sample completely undisturbed, and at the same time it would be difficult to hit veins at all with a conventional syringe, which the bug can easily do.
Action
Venous blood collection, the blood in the vein by means of a tourniquet , also called tourniquet, jammed. In cases where congestion phenomena falsify the laboratory result, the non-congestion is required, e.g. B. when removing lactate tubes .
As explained further in the section on preanalytical aspects for the laboratory, care must be taken to ensure that the congestion is neither too strong nor too weak or too long, otherwise numbness may arise. If the stowage is too weak, e.g. B. problematic large upper arm circumferences with inadequately high-quality stasis tubes made of too loosely stretchable material can in practice lead to major problems in locating the vein and several, time-consuming puncture attempts, which make both the patient and the doctor nervous, especially in an emergency situation can lead to sometimes unnecessary more invasive measures such as the creation of a CVC . If necessary, blood can of course also be withdrawn via the latter as well as via ports or freshly placed, wide-lumen peripheral venous catheters , but there is a higher risk of hemolysis of the sample material. In particularly severe cases, the use of blood pressure cuffs is also recommended for the purpose of more even and larger pressure, whereby the puncture can even be inflated over-arterially and pressure can then be released again for removal. Physical measures such as warm baths and fist making and pumping are also possible, but time-consuming and preanalytically critical. If all fails, the radial or ulnar artery on the wrist can exceptionally be punctured, but this should be done by an experienced doctor.
With an alcoholic disinfectant which is skin disinfected over the puncture site. The vein is punctured with a sterile cannula , nowadays mainly with wing cannulas because of its easier handling , and the blood collection tubes are attached one after the other . In advance, attention is paid to signs of possible syncope in the patient due to the psychological stress situation. In the case of sparse blood flow, wing cannulas can be successful in lifting the butterfly a little or carefully pushing it back and forth in the vessel in order to avoid possible wall adhesion effects or venous valves lying on the opening.
Depending on the blood flow, the congestion is released now or only after the tubes have been removed. With the aspiration principle, the blood is drawn into the blood collection tube by withdrawing a plunger. With the vacuum principle , this happens due to a vacuum ( negative pressure ) in the tube . After the blood has been taken, the cannula is withdrawn, secured and disposed of in special cannula disposal boxes, and the puncture site is gently pressed off and provided with a plaster or swab . When determining z. B. the ammonia value , the tube must be placed on ice immediately afterwards , either wrapped in a container with crushed ice or, more laboratory-friendly, in appropriate gel packs and brought to the laboratory. Routine profile values should also be submitted to the laboratory as quickly as possible, because the fresher the blood, the more precise and faster the analysis. In the case of completely isolated patients, the binding hygiene regulations must be observed with regard to the removal and transport of the tubes .
Congestion of the vein
Blood collection
Preanalytical Aspects
An upright posture can lead to increased readings, including for cellular components, but also total protein (up to 10%), enzymes , albumin , calcium and magnesium . Therefore, the blood collection should be carried out with the patient sitting or lying down. Opening and closing the fist several times during collection can lead to an increase in potassium and magnesium . A strong physical exertion before the blood sample first leads to the hemoconcentration (increased hematocrit and further analyzes ), later to an increase in muscle enzymes (increase in myoglobin and creatine kinase ). Exposure to daylight leads to a reduction in bilirubin , creatine kinase, folic acid and porphyrin concentrations . If the tube is not closed (even in the refrigerator), plasma water can evaporate. This leads to an increase in the concentration of most parameters ( proteins , electrolytes ). To avoid hemolysis one should use at least 21G cannulas. In addition, the time between the onset of venous congestion and the start of blood collection should not exceed one minute, as intravascular hemolysis can otherwise occur. The tubes should not be shaken, but should be mixed by gently tilting them several times. No more than 30 minutes should elapse between the blood collection and centrifugation, as otherwise there may be an increase in cellular soluble substances (e.g. potassium). The collection time should be specified, especially in the case of repeated measurements on the same day (e.g. before and after surgery and therapies, drug levels), but also for parameters with a circadian rhythm, e.g. B. iron , cortisol , zinc or food addiction ( glucose , triglycerides ). For coagulation tests (light green tubes) the tubes must be filled to the mark (the ratio between citrate and blood must be exactly 1: 9) to allow a correct determination. Inappropriate storage (too light, unlocked, too long, too cold or warm) can lead to incorrect measured values.
Sample containers
- → Main article blood collection tubes
The sample containers (blood tubes) are used to take and prepare blood samples. Furthermore, they enable the uncomplicated transport and short-term storage of the samples taken. Depending on the use, they contain additives. There are two different color coding systems, the Euronorm (EN) coding is common in Europe, while the ISO color coding is generally used in the USA .
Color coding
| Type | EN 14820 | DIN / ISO 6710 |
|---|---|---|
| Serum without additives | White | red |
| Serum with separating aid (gel) | brown | Golden yellow |
| EDTA blood - complete blood count | red | violet |
| EDTA intolerance | White | |
| Citrated blood (1 + 9) - coagulation | green | Light Blue |
| Citrated blood (1 + 4) - ESR | violet | black |
| Li- heparinate - blood , blood gas analysis - plasma | orange | green |
| Fluoride ( NaF + oxalate ) | yellow | Gray |
Order of the tubes when taking a blood sample
- Serum tubes
- Citrate tubes, BSG
- Heparin tubes
- EDTA tubes
- Fluoride tubes
In general, the recommendations are to draw citrated blood (3) before the rest of the tubes with additive, but not first. For these (4–6) the order is not given uniformly.
Forced blood collection
The forcible blood collection (primarily to clarify the ability to drive or the determination of the time of the crime blood alcohol concentration of suspects after a crime ) is in Germany to § 81a Code of Criminal Procedure possible. It may only be carried out by a licensed doctor on the order of a judge ; in exceptional cases (e.g. if a judge cannot be reached and if some criminal offenses are suspected) the public prosecutor or their investigators (e.g. police officers ) may order the blood to be taken instead . Until 2017, the exceptions were much narrower, but were often relaxed in practice. In some cases, no attempt was made to obtain the approval of a judge, and instead it was assumed that an order from a public prosecutor or an investigator from the public prosecutor would also be sufficient, since in the opinion of the public prosecutor and the police it was always a matter of “imminent danger” if this has been expressly criticized in a judgment of the Federal Constitutional Court . The blood can then also be taken against the will of the accused, if necessary with physical violence. Under certain circumstances, this makes himself liable to prosecution according to § 113 StGB ( resistance against enforcement officers ).
In Austria , on the other hand, a compulsory blood withdrawal is not legally possible, as this is viewed as incompatible with the principle of the prohibition of compulsion to blame yourself. However, according to Section 123, Paragraph 4 of the Code of Criminal Procedure, there is an exception that compulsory blood tests or similar minor interventions are permitted under certain circumstances. If an accused is suspected of having deliberately endangered people through communicable diseases ( Section 178 StGB) or a "crime against life and limb by performing a dangerous activity in a state of being drunk or otherwise impaired by an intoxicating substance", or if the " physical examination of the accused to investigate a criminal offense threatened with more than five years imprisonment or a crime according to the 10th section of the penal code "(criminal acts against sexual integrity and self-determination), a forced blood sample is allowed.
Under Swiss law, if the blood sample is refused, the consent of an examining magistrate must be obtained, and on whose order this can then be carried out by a doctor using police force.
Web links
Individual evidence
- ↑ File number VI ZR 72/74
- ↑ Uwe Gille: Cardiovascular and immune system, Angiologia. In: F.-V.Salomon et al. (Hrsg.): Anatomie für die Tiermedizin . Enke-Verlag, Stuttgart 2004, pp. 404-463. ISBN 3-8304-1007-7
- ↑ Monika Böttle et al .: Hematological examinations in ferrets (Mustela putorius furo). In: Kleintierpraxis 44 (1999), pp. 673-682.
- ↑ Jutta Hein: Blood sampling and examination of small mammals. In: Kleintierpraxis 56 (2011), pp. 482–494.
- ↑ Planet-knowledge , Video @ 2370sec.
- ↑ Practical instructions for taking blood samples . Horst Gross. September 3, 2014. Retrieved November 7, 2015.
- ↑ a b Institute for Clinical Chemistry at Ulm University : Sample collection and extraction systems ( Memento from November 14, 2011 in the Internet Archive )
- ↑ NCCLS - Procedures for the Collection of Diagnostic Blood Specimens by Venipuncture; Approved Standard - 5th Fourth Edition H3-A4 Vol.18, No.7, June 1998.
- ↑ Jakob Pichon: Neverending Story: News on the judge's reservation for blood withdrawals (§ 81a Abs. 2 StPO) , HRR-Strafrecht 11/2011, 472
- ↑ Copyright Haufe-Lexware GmbH & Co KG - all rights reserved: The judge's reservation for blood samples has been largely repealed by law. Retrieved June 9, 2020 .
- ↑ BVerfG, decision of June 11, 2010 , Az.2 BvR 1046/08, full text.
- ↑ M. Vergeiner, C. Riccabona-Zecha, S. Mesecke: Participation in road traffic under the influence of drugs. A comparative legal analysis of Austrian and German public law. Zeitschrift für Verkehrssicherheit 3/2004, p. 126 ( ( page no longer available , search in web archives: http://www.kfv.at/fileadmin/webcontent/Publikationen/Fachartikel/VM/ZVS-DrogenimVerkehr.pdf online ) (PDF File; 692 kB)).
- ↑ Service order DBF90005 of the Police and Military Directorate of the Canton of Bern ( online ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. ).
