Year 1 MBChB Clinical Skills Session Blood Glucose Monitoring

Transcription

1 Reviewed & ratified by: Year 1 MBChB Clinical Skills Session Blood Glucose Monitoring Dr V Taylor-Jones, Ms C Tierney & elements discussed with Ms Lesley Lamen, Diabetic Nurse Specialist RLBUHT Blood Glucose Monitoring

2 Aims and Objectives Aim: For the student to be able to take a capillary blood glucose safely. Objective: The student will know the indications for performing a capillary blood glucose. Objective: The student will know how to obtain a capillary blood sample and be able to test this. Objective: The student will be aware of some of the factors affecting validity/ reliability of capillary blood glucose monitoring. Theory and background Capillary blood glucose testing is a quick and convenient tool for assessing a patient s blood glucose, please remember the gold standard would require a venous sample. Blood Glucose Glucose is an important carbohydrate and vital source of energy. Blood glucose levels are tightly controlled by homeostatic processes to range between mmol/l. In healthy individuals the level remains in this range despite varying amounts of food, exercise or fasting. There are a number of conditions where this control may be lost resulting in higher or lower blood glucose e.g. Diabetes mellitus Cushing s syndrome Pancreatic carcinoma Blood Glucose Testing 2

3 This provides a rapid diagnostic tool in an unwell patient to aid diagnosis, for example in A&E departments, walk-in centres, GP surgeries, or by paramedic/ambulance services. This test will be performed regularly in these area. However blood glucose testing also enables blood glucose monitoring, over the course of a day or long term, usually to maintain optimum levels. e.g. self-monitoring, care homes, diabetic clinics, palliative care etc. Hyperglycaemia is a patient with an elevated blood glucose level Hypoglycaemia is a patient with a low blood glucose level Normal and diabetic blood glucose levels For the majority of healthy individuals, blood glucose level in is about 4 mmol/l Shortly after a meal the blood glucose level may rise temporarily up to 8 mmol/l For people with diabetes, blood glucose level targets are as follows: Before meals: 4 to 7 mmol/l for people with type 1 or type 2 diabetes After meals: between 5-9 mmol/l for people with type 1 and under 8.5mmol/L for people with type 2 Symptoms of hyperglycaemia Symptoms are often insidious in onset yet may include: o Polydipsia (increased thirst). o Headaches. o Difficulty concentrating. o Blurred vision. o Polyuria (frequent urination) o Fatigue (weak, tired feeling) o Weight loss. o Blood glucose levels greater than 7.0 mmol/l when fasting o Blood glucose levels greater than 11.0 mmol/l two hours after meals (Diabetes.co.uk 2017) 3

4 Symptoms of Hypoglycaemia [Blood glucose less than (<) 4 mmol/l (Diabetes.co.uk)] Early symptoms of hypoglycaemia, are usually of rapid onset and may include: o Dizziness. o Feeling shaky. o Feeling sweaty o Hunger. o Headaches. o Irritability. o Confusion. o Pounding heart; racing pulse. o Pale skin Results of Hypoglycaemia and Hyperglycaemia Hyperglycaemia Although blood sugar levels exceeding 7 mmol/l for extended periods of time can start to cause damage to internal organs, symptoms may not develop until blood glucose levels exceed 11 mmol/l. Hypoglycaemia Mild hypoglycaemia is usually treated quickly and is not usually associated with long term health problems, however, severe hypoglycaemia will need treatment, if untreated it could potentially lead to coma and death (Diabetes.co.uk 2017). 4

5 Type Target before meals (pre prandial) Target 90 minutes after meals (post prandial) Non-diabetic Diabetes.org.uk (2015) Type 2 diabetes (Diabetes UK Council of Healthcare Professionals 2015) Type 1 diabetes Nice Guidelines 2015 Children w/ type 1 diabetes Nice Guidelines to 5.5 mmol/l under 8 mmol/l 4 to 7 mmol/l under 8.5 mmol/l 4 to 7 mmol/l 5-9 mmol/l 4 to 7 mmol/l 5-9 mmol/l Patient Safety 5

6 Other safety issues A small, sharp, disposable lancet is used to prick a finger and obtain a small drop of capillary blood. Please revise and be familiar with: o Universal precautions o Safe handling of sharps and needlestick procedures o Minimising contamination / injury o Control of bleeding o Correct disposal of contaminated waste Fainting Only a small drop of blood is obtained so fainting is unlikely. However people can feel queasy at the sight of blood or the thought of pain, ask the patient if they have any concerns or history of fainting. If required position the patient on a bed/couch because if the patient faints you have to maintain their safety. If your patient faints summon help by shouting for assistance, place the patient in a safe position (ideally flat with legs raised), stay with them until they have recovered. Maintain their airway, check their blood glucose (dispose of sharps safely), get further help if blood glucose is abnormal or they do not recover. Selecting an Appropriate Site If the patient is unwell, hypo or hyperglycaemic a capillary blood sample may be taken. Be aware that accuracy of reading varies from site to site, generally, the higher the blood flow, the more accurate the measurement. Fingertips are used as the blood flow here is 7 times higher than other sites. 6

7 There are other sites which can be used if fingertips are unavailable, speak to staff in the department for advice on what is appropriate for each patient, some sites that may be used; o Palm o Forearm o Upper arm o Thigh o Calf o Ears o Heel Selecting an appropriate finger Do not use a finger if there are any o Wounds o Rashes o Skin lesions o Evidence of infection o And avoid dominant hand, thumb and index finger Do not use the same site repeatedly Maximise blood flow to fingertip by: o Ensuring a warm environment o Washing hands in warm water o Lowering arm below heart level Copyright image; Crystl at 7

8 Inaccurate results Please be aware that many conditions may give inaccurate results. In these cases a venous sample should also be taken, and is the more reliable sample. Caution should be taken with patients presenting with the following; o Cyanosis o Poor peripheral perfusion o Peripheral oedema or swelling o Patients suffering with excessive blood loss/ anaemia o Patients with an intravenous infusion in close to the puncture site o Severe dehydration/ shock Procedure Prepare your equipment before you begin, listed below is the equipment you should require; o Suitable environment o Gloves (non-sterile) and apron o Hand-washing facilities o Blood glucose meter (glucometer) o Blood glucose test strips (in date, correct code) o Safety Lancets o Sharps box o Swab / sticking plaster, to stop any bleeding o Documentation 8

9 Hand washing Both you and the patient should wash and dry your hands thoroughly with soap and water (this removes surface contaminants which may alter reading e.g. if the patient has been handling sugary sweets). Avoid alcohol hand wash as alcohol dries and hardens the patient s skin with frequent use. If used at least 30 seconds should elapse before taking the sample to ensure all residue has evaporated. Any residue of water, soap or alcohol will give a false result. You must wear gloves and apron as per national guidance (epic3, Loveday 2014) Glucometers (Blood Glucose Meter) There are many devices available You should familiarise yourself with the type of device used in your particular clinical area Ensure that you adhere to Trust and manufacturer guidelines Devices that you may see in the Trusts require users to be trained in their use. These devices link directly with the laboratory through scanning of barcodes and aim to ensure that no data is lost. Permission kindly granted by Roche UK to 9

10 Ensure the machine has been recently calibrated as per trust policy and ensure the correct test strips are used with the correct machine Blood Glucose Test Strip These are single use, individual test strips are stored in an airtight container. You should: o Check the expiry date o Ensure the container is tightly closed (prolonged exposure of strips to the air will give false results), discard if required o Test strips contain enzyme-impregnated reagent and they must be kept in a cool, dry environment away from heat or light There are two ends to the test strip The golden end is inserted into the glucometer. The tip of the yellow window is touched to the blood drop and draws up blood. 10

11 Ensure test strip is compatible with meter. (Check the codes match, if applicable) Take test strip out of bottle and replace cap on bottle immediately avoiding prolonged exposure to air Insert a test strip into the meter only when you are ready to obtain the blood sample Single use Lancet You will come across different lancets in your Trusts, there are different needles for different depths. Some examples below; 11

12 Single use Lancet with different depth settings In this case; twist the purple cap to the depth you require Set on high- this will pierce the patient s skin deeply Single use Lancet Set on medium this will pierce the patient s skin more superficially The side of the finger is the preferred puncture site. Apply the lancet with a little pressure to the side of finger. Warn the patient e.g. sharp scratch As you press the trigger down Dispose of lancet immediately in sharps bin. 12

13 If capillary blood sample not immediately available, count to 5 then squeeze the finger from the bottom to obtain a small drop of blood (approx. 0.6 microlitres). Please avoid touching the puncture site and avoid smearing the blood (test strips will not work) Avoid texting or typing fingers. Once the strip is in the machine, an egg-timer flashes and then the machine shows a drop of blood. Only start the test when the droplet is visible on the device. Touch front edge of yellow window of test strip to drop of blood and the test strip draws up blood DO NOT put blood on top of strip. The result appears on the display immediately, once finished remove the used test strip. The test strip should touch the apex of the blood droplet The blood glucose level should then be displayed on the glucometers screen. 13

14 Disposal of waste Lancets must go immediately into the sharps bin after use, please dispose of gloves, apron, paper towel, gauze and strips into orange clinical waste bag. Ensure that you wash your hands following the procedure. Documenting Results Please report abnormal results immediately to a senior member of staff, and document clearly. Any abnormal readings will need re testing and a venous sample should be taken, by a member of staff qualified to do so. References and other Useful Resources Sources and useful resources Clinical Skills for Student Nurses: Theory, practice and reflection. (2008) Ed. Richardson R, Reflect Press Ltd, London. pp Clinical Skills Explained. Akunjee M et al (2012) Scion Publishing Limited Banbury.pp Loveday (2014) Epic3; National evidence-based guidelines for preventing healthcare associated infections in NHS hospitals in England. Accessed August 2017; ence-based_guidelines_for_preventing_hcai_in_nhse.pdf 14

15 Underlying anatomy and Physiology Peer Feedback 03 Y1 BM peer feedback.docx Video Glossary Glucometer Blood glucose meter Hyperglycaemia High blood glucose levels Hypoglycaemia Low blood glucose levels Polydipsia Increased thirst Polyuria Frequent urination Pre-prandial Before a meal Post Prandial After a meal 15