BLOOD GLUCOSE MEASUREMENT Mary Clynes, Colleen O’Neill and Sara Raftery Chapter 19

Introduction This presentation examines the blood glucose measurement procedure and the rationale for carrying it out Part 1 – Blood Glucose Measurement Overview Part 2 – Indications and Contraindications for Blood Glucose Measurement Part 3 – Blood Glucose Measurement Pre- Procedure Patient Care Principles Part 4 - Blood Glucose Measurement Procedure Patient Care Principles Part 5 - Blood Glucose Measurement Post-Patient Care Principles

PART 1: Blood Glucose Measurement Overview

Definition Blood glucose monitoring is a procedure to establish the measurement of glucose in the blood.

Normal Measurement Blood glucose levels are measured in mmol/l. The normal range for an adult is mmol.l The normal range for a child is mmol/l and a neonate is mmol/l (Skinner 2005).

PART 2: Indications and Contraindications for Blood Glucose Measurement

Indications In diabetics, take care to monitor blood glucose levels. The readings can assist the mdical team in adjusting insulin levels (Alexander et al, 2006). To detect hypoglycaemia (low blood sugar) or hyperglycaemia (high blood sugar). To monitor patients on parenteral nutrition to ensure that blood glucose levels are within acceptable limits. It is important to be aware that hyperlipidaemia (raised blood lipids) may alter blood glucose reading. To monitor patients who are taking hypogylcaemic medications. To eliminate diabetes mellitus as the cause of in patients who present in an unconscious.

Blood Glucose Monitor There is a variety of blood glucose monitors available. They vary depending on size, testing speed, amount of blood needed for the test, ability to store test results in memory, cost of meter and reagent/test strips. It is important to follow manufacturers’ instructions for storage and blood monitoring techniques. Compatible test/reagent strips should be used. Ensure that you are familiar with the workings of the equipment. Only staff who are specifically trained should use the monitor. Before carrying out the procedure, ensure that the blood glucose monitor is checked and is in working order to ensure accuracy of result. Monitors should also be calibrated as per manufacturers’ guidelines to ensure an accurate result.

Contra-indications Staff need to be aware that certain conditions may give false results and in those instances a laboratory measurement using a venous blood sample is required. Results may be affected by the following: Dialysis treatment Hyperlipidaemia Severe dehydration High and low haematocrit values High bilirubin values Peripheral circulatory failure Intravenous infusions of ascorbic acid (Vitamin C) Patients receiving intensive oxygen therapy (MHRA, 2005)

Responsibilities In order to provide safe, competent care to patients an understanding of the principles and processes related to blood glucose monitoring is necessary. HCPs need to be aware of their role in the pre-procedure phase, procedure phase and post insertion stage.

PART 3: Blood Glucose Measurement: Pre- procedure Patient Care Principles

Pre-Procedure Patient Care Wash hands and put on gloves and apron to prevent contamination with blood and reduce the risk of cross-infection. Explain the procedure to the patient in order to gain consent and co-operation. Discuss with the patient any concerns or queries to minimise patient anxiety. Check that consent has been obtained. Collect and prepare the equipment in order to carry out the procedure smoothly and without unnecessary stoppages.

Equipment: Blood glucose meter Test/reagent strips A spring-loaded finger pricking device and sterile lancets Cotton wool balls Non sterile gloves and apron Sharps bin Record sheet Receptacle for waste material

PART 4: Blood Glucose Measurement Procedure Patient Care Principles

Ask patient to wash hands with soap and water prior to taking sample, to reduce skin microbial load. The warm water dilates the capillaries and increases blood flow. Provide assistance as appropriate. Alcohol wipes should not be used to clean puncture site, as alcohol interferes with test/reagent strips and repeated use toughens skin. Ask patient to sit or lie down to ensure patient safety. Some patients may feel faint when a blood sample is taken. Select puncture site. The side of heel or side of finger are potential sites. Avoid using back of heel and tips of fingers to reduce pain and prevent damage to underlying nerves. Procedure Patient Care

The site should be rotated to reduce the risk of infection from recurrent punctures, prevent the areas becoming hard and reduce discomfort. Insert the lancet into the spring-loaded device. Remove protective cap from lancet. Place the sterile lancet firmly against selected area and press the release button to obtain blood sample. The lancet will immediately puncture the skin. Gently squeeze finger or heel to produce a sufficient sample of blood to ensure accuracy of result. Avoid massaging blood from the puncture site. This may result in damage to the tissues and the subsequent seepage of tissue fluid will give a false result. (Skinner, 2005).

Position finger in downward position to aid the flow of blood. Ensure that there is sufficient blood to cover the reagent/test strip. Do not smear or spread the blood on the strip. Continue as per the manufacturer’s instruction as the procedure may vary depending on the type of monitor. Apply cotton wool to puncture site and apply pressure to prevent further bleeding and to prevent haematoma formation.

PART 4: Blood Glucose Measurement Post- Procedure Patient Care Principles

Post-Procedure Patient Care Dispose of lancet in sharps bin to reduce the risk of needle stick injury. Dispose of waste appropriate to prevent the spread of infection. Ensure bleeding has stopped and patient is comfortable. Remove and dispose of gloves. Wash hands or clean with bactericidal solution to prevent cross-infection. Read and record result as soon as it is displayed on the monitor to ensure accuracy. The nurse must know the normal blood glucose range so that abnormalities can be recognised and treatment provided as appropriate. Careful and thorough documentation is important to ensure accurate record of the procedure and nursing care provided.