How to Draw Blood – The Definitive Guide
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Drawing blood is one of the most important medical procedures. It represents basis of diagnostics and it helps establish the current health condition of a patient. But, even though it is a routine procedure, it may represent quite a task on occasion. In a sense, how to draw blood is a really specific process given that it can be used both for your benefit (when performing analysis) and other people’s benefit (when donating blood).
Like with other body parts, veins differ from patient to patient. Some individuals have visible veins while in others, they are barely noticeable. On top of that, different people react differently when they need to draw blood. There are those that are afraid of needles. Some people faint at sight of blood. All of these things can pose quite a problem and may even represent a threat to a patient.
With this guide, we will give you some tips and instructions as to how to draw blood from a vein and most importantly, how to do it safely.
There are numerous steps of phlebotomy. You start by preparing a patient before he comes to a laboratory. If a person is performing biochemical analysis, such as determining sugar level, cholesterol, triglycerides, iron, he needs to avoid eating any food 12 hours before the procedure.
The day before drawing blood, the patient needs to eat lighter food up until 18h. After 18 o’clock, it is possible to drink liquids, except for alcohol, coffee, and sweet beverages. This is a must, given that food intake can increase the level of measured parameters.
Sometimes, for the best results and based on doctor’s recommendation, blood should be taken when the patient stops his therapy and after the medicine passes through his organism. Therapy can have a big impact on levels of different substances in patient’s blood. In order to get the best measurement, patient’s entire therapy needs to end so that we can determine the basic values. Precautionary measures are especially necessary if the patient has previously received iron or vitamin therapy.
All of these instructions are crucial when analyzing blood. In case of blood donation, a bit different rules apply. Donor should have a proper level of iron in his organism. Good night sleep is a must giving that the procedure can drain a person. Similarly, it is important to drink a lot of water and have a nice, big meal beforehand. Fatty food should be avoided. Also, person shouldn’t have any traces of medicines or aspirins in his organism.
Preparation for the procedure
Venipuncture starts by introducing yourself to a patient. Although this is a routine procedure, it is necessary to establish trust. As we previously emphasized, some people have a hard time with needles or blood. This is why you, as a medical professional, need to help circumvent these fears. At the same time, it is a good way to start a conversation and relax a patient.
After that, it is customary to explain the procedure. This step is especially important for little children and those who are doing venipuncture for the first time. Drawing blood lasts for less than 3 minutes. It is necessary information that has to be highlighted. Point out that the procedure is really quick and that a patient will feel a slight prick followed by mild discomfort. Avoid telling patient that phlebotomy is performed without pain. For someone who fears needles or blood, this can have quite a negative effect occasionally resulting in panic.
Sanitization is the next step of the process. Make sure to wash your hands and put on a pair of gloves.
Now, you are ready to confirm requisition. It has to have patient’s information such as date of birth and medical record number. Requisition has to be stamped! It is necessary for requisition and labels to match with patient’s identification. The last piece of the puzzle is determining patient’s identity. This can be done either by checking his wristband or by asking him the question directly.
When donating blood, establishing the blood type is crucial unlike during analysis. As a doctor, you need to make sure that a person is eligible for blood donation. The individual has to be well rested and he mustn’t have any disease which can be transferred through blood (such as STD’s).
It is your duty to make sure that the procedure is properly done and that donor can leave the facility on his own power. Full anamnesis has to be performed, both by talking with a person and by performing the necessary analysis. Toxicology needs to be done so that you can determine if the person has alcohol or drugs in the blood.
Next step of the process is gathering all of your supplies and equipment in one place. You will require blood collection tubes, cotton balls, bandage, a tourniquet, alcohol wipes and medical adhesive tape. As an additional precautionary measure, you will have to check the date on blood culture bottles and blood tubes.
If there are any additives on the walls of the tubes, you will have to dislodge them by tapping on the tube itself. In case they have expired, it may jeopardize the integrity of the seal. The last thing that you have to do is to choose the needle. Based on patient’s physical characteristics, his age and amount of required blood, type of needle may vary.
Start of the venipuncture
When you are certain that you have all the necessary equipment at your fingertips and that you identified the patient, you can have him seated. Given the procedure, it is necessary for a chair to have armrests. The arm should be straightened. In case that a patient is lying in bed, make sure to place a pillow under his arm. It will provide more support.
Pick the arm from which to collect blood. Tourniquet needs are tied around individual’s arm. Place it at 3” to 4” above the venipuncture site. In order for veins to be more visible, the patient needs to clutch his fist. Fist shouldn’t be pumped, just clutched. When the vein is ready and the patient has done everything to make it more noticeable, you will have to use your index finger and start taping it. This will further encourage dilation.
Wipe covered in alcohol needs to be used on the venipuncture site. It will disinfect the area. When using the wipe, you will have to make circular motions. At the same time, if you already covered certain area with alcohol, you shouldn’t cover it twice. Given that alcohol interacts with blood and can cause a stinging sensation, it is necessary for a doctor to wait for 30 seconds until it evaporates.
Get the needle. Make sure that it is intact. Broken needle can endanger patient. You should be looking for any type of obstruction or hook that might restrict the flow of blood or hurt the person. Put it in a holder. Now, you need to make sure that the needle is secure in place. You will have to use needle sheath for this.
Blood collection tube needs to be placed into a holder. Take the patient’s arm. Thumb needs to pull the skin taut for 1” to 2” bellow the puncture site. The arm needs to be pointing downwards. Depending on a patient, it will be harder or easier to find the vein.
In most cases such as with patients that have low body fat, the vein will be noticeable in sight. Nevertheless, touch is necessary as the way to find the vein and safely perform the procedure. After finding it, you need to know how to hold a needle when drawing blood. Bevel needs to go upwards.
Sometimes, veins on the surface will be hard to notice. In those situations, there are several ways to stimulate the veins and increase the influx of blood. This will be discussed in details in following chapters.
Finally, you have reached the insertion point. Upon introduction of the needle, collection tube needs to be pushed until it’s in place. In this situation, blood will start flowing downwards. This is why the tube needs to be below the insertion site. Wait for a bit until the tube is full after which you may discard tourniquet.
When the entire procedure is finished, the tube needs to be removed from the holder. Be careful not to shake the tube. Same procedure needs to be repeated for other tubes as well. The samples shouldn’t be mixed in any way. The patient can now stop clutching his hand as you remove needle and place gauze over the insertion point.
Bleeding needs to be stopped after this step. By holding the gauze in place and pressing it, you are able to do this.
Order of draw
When drawing blood for analysis, you will have to take several samples. You need to perform this in a certain order that will prevent cross-contamination of additives between tubes. Here is the best order of tubes:
- Blood culture – yellow or yellow-black top
- Coagulation – light blue top
- Non-additive – red top
- Additives (SST with red-gray or gold top, sodium heparin with dark green top, PST with light green top, EDTA with lavender top, ACDA or ACDB with pale yellow top and oxalate/fluoride with light gray top).
Always remember; when using tubes with additives, they have to be thoroughly mixed.
Cleaning the working area
Similarly to other medical procedures, it is necessary to uphold the highest standard of hygiene which will protect not only patient’s health but yours as well. This will prevent any type of contamination. You need to start by putting the needle and syringe into a container. Have in mind that you need to discard different items in appropriate containers. For example, items that are not contaminated with blood can be placed into general waste. Be careful with objects that have blood on them; they are the real cause for concern. Forms and labels need to be double checked just in case there is some inconsistency. You can easily make a mistake by putting a wrong name or date of birth. This can cause quite a problem for the laboratory team.
Naturally, after discarding is over, you will have to perform hand hygiene. Tell the patient that venipuncture is over and ask him how he feels. Drawing blood can cause nauseating feeling and it can even lead to patient fainting. Instruct him to leave the gauze in place for at least 15 minutes. This is the necessary time that will allow coagulation to start.
After the patient leaves your office, make sure to clean the armrest with germicidal wipes. When the person leaves your office, you are ready to submit samples to the laboratory (in case that you are taking them for analysis).
How to behave during the procedure
Again, even though this is a routine procedure, there is a common practice for a medical professional. It is necessary to create a solid relationship with a patient and to instill trust. Medical procedures can be really troubling. To be honest, there are a lot of people who hate going to a doctor’s office. For them, venipuncture represents a really stressful procedure.
The most important thing which you can do for your patient is to talk to him. Doctors usually neglect this as they automatically start drawing blood from a patient. In these situations, it is easy to lose track of a person who is being analyzed. However, talking to the patient can have multiple purposes. If his veins are hard to hit, the patient may give you a good advice and point you to a vein that is more noticeable.
Communication is very important when performing the analysis. Unlike blood donors who are small in numbers and are used to giving blood, many people who are performing analysis are not accustomed to it. By talking to them, you may distract them thus relaxing them. If blood makes a person nauseous, instruct him to look away from the needle and insertion point.
That being said, your duty as a professional is to make the entire experience as pleasant as possible. Have in mind that some of the patients are particularly difficult to deal with. Occasionally, pleasantries will not do you much good. This is when you have to find a balance between professionalism and politeness. No matter what happens, you shouldn’t be flustered by the patient’s behavior. You have to keep a level head and concentrate on the process. Otherwise, you are risking of missing the vein and endangering patient’s health. As someone who is doing this job, you have to prepare for such patients in advance.
Finding the proper insertion point
The best way to draw blood is to select larger median cubital and cephalic veins. However, it is a normal practice to use dorsal hand veins and basilic vein on the dorsum. It is always better to draw blood from arms. Feet are the last resort given the possibility of complications.
There are certain areas which need to be avoided at all costs such as:
- Avoid scared or burnt tissue; they are very hard to penetrate
- Hematoma may lead to erroneous results. If there is no other place to take blood from, you can opt for area distal to hematoma
- The upper extremity on the side of a previous mastectomy
- Taking a sample from intravenous line may prove to be easy but can lead to some other issues. It is required for line to be flushed prior to procedure so that you can avoid hemolysis.
- Intravenous therapy or IV therapy (as well as blood transfusions) can lead to dilution of the specimen due to the fluid. If possible, take a sample from the other arm. Nevertheless, it is still possible to get a good sample from an arm with IV therapy as long as you turn IV for at least 2 minutes prior to the procedure. Then, you have to place tourniquet bellow IV site. Naturally, you have to choose some other vein that isn’t used for IV therapy. Lastly, draw 5 ml of blood and then discard it before taking the specimen tubes for testing.
- In case of edematous extremities, there is a high chance of tissue fluid accumulation to affect test results
- When it comes to drawing blood from an arm with a fistula or cannula, most of the hospitals have special polices. This is another thing to have in mind
How to draw blood from a patient if you cannot find a vein
First thing that you wish to try is placing a tourniquet. It constricts the arm, increasing the available amount of blood within the veins. This way, they will be much easier to spot. However, you shouldn’t overdo it because you do not wish to cut off the circulation. The tourniquet has to be placed four inches above the vein.
Another good way to do it is by placing warm pack or bottle cloth over the area. It will lead to dilation and expansion of veins. It is very important to put a pack before disinfection. If you put it after, you will have to disinfect once again. Warm pack shouldn’t directly touch the skin. If it turns out that the bottle or a pack are too hot, it may lead to burns. Naturally, you should try to do entire process of phlebotomy without pain or with minimum pain possible. This is why you should wrap it in a towel before placing on arm.
Relaxation can also be used to your advantage. People who have phobias involuntary constrict their muscles due to stress. This will make it harder to take a blood from a vein. By relaxing the patient, it will be much easier for you to draw blood.
Rubbing the vein is another good method that may help you to locate the vein. Slowly go over the arm, trying to find the right place where you can insert the needle. Here, you have to use your index finger. Thumb has a pulse of its own and it may be confusing for you to find a proper vein due to this fact. Patient shouldn’t slap his arm or do anything else to forcefully stimulate the vein. It can lead to bruising.
In certain situations, needle will penetrate the skin and at the last moment, vein will move away. If this happens, patient needs to remain perfectly still. Best thing that you can do is change the entry angle until you hit the vein. During this, needle shouldn’t be removed from under the skin. This can be very uncomfortable for patient but it is the best and quickest solution. Again, this is a thing of practice.
If all of this doesn’t help and you still miss the vein (even with all the preparation), you can still try again. Try hitting the vein just below the initial insertion point. Have in mind that you can miss again. This may be a result of dehydration or some other issue. If you do not have enough experience, it is best if you ask senior college or supervisor for help.
Additional things to have in mind
Besides mentioned issues, there are other things which may happen during the venipuncture. Because of that, you have to take preventive measures that will protect individual’s health.
1. Prevention of hematoma
- Only the uppermost wall of the vein should be punctured
- Puncture one of the major superficial veins
- Tourniquet needs to be discarded prior to removing needle
- Patient has to apply pressure to the insertion point
- Needle needs to fully penetrate the vein. Otherwise, this can lead to leakage of blood into soft tissue
2. Indwelling lines or catheters
- Solution of heparin is used in order to reduce the potential risk of thrombosis
- This can lead to test error
3. Prevention of hemolysis
- Hemolysis can easily affect test results
- You shouldn’t draw blood from hematoma
- Venipuncture site needs to be dry prior to procedure
- Tubes with anticoagulant additives need to be stirred gently
- Plunger shouldn’t be drawn back forcefully
- Vein shouldn’t be punctured forcefully
- Fist clenching should be avoided
4. Prolonged tourniquet application
- In case that you leave tourniquet for a longer period of time, it may result in hydrostatic pressure which in terms will cause water and filterable elements to move from extracellular space
- It may lead to hemolysis with pseudohyperkalemia
- By leaving tourniquet for a prolonged time, it may affect packed cell volume
- This can also lead to increase of proteins, lipids, cholesterol, iron and aspartate aminotransferase
5. Prevention of hemoconcentration
- Again, this can occur due to prolonged tourniquet application
- Avoid prolonged IV therapy
- Avoid massaging, squeezing or probing the insertion site
- Pay attention to sclerosed or occluded veins