Insulin pump therapy is an option for many patients with type 1 diabetes. Identification and education are key if patients are to be successful with this treatment.
Patient-operated medical devices are now an option for many long-term conditions. Insulin pump delivery systems are one example used in the management of type 1 diabetes. As nurses in all settings are likely to meet patients using this insulin delivery device, this article will pay attention to how the insulin pump works, who would gain most benefit, the advantages and challenges of wearing this device, and how to start a patient on an insulin pump.
How the insulin pump works
Insulin pump therapy, also known as continuous subcutaneous insulin infusion (CSII), involves the use of a small portable battery-operated mechanical device which resembles a pager. The majority available in the UK continuously infuse rapid acting insulin via reservoirs which attach to infusion sets and a plastic cannula which stays in place with adhesive tape for up to three days. The pump is worn discreetly under clothes or on a belt.
In a person without type 1 diabetes the pancreas continuously releases small amounts of insulin, and when food is consumed, insulin production automatically increases to maintain normal blood glucose regulation.1 In type 1 diabetes an insulin pump mimics this process by delivering quick acting insulin such as Humalog®, Novorapid® or Apidra® continuously day and night. To replace background insulin such as Insulatard®, Levemir® or Lantus® used in a multiple daily insulin (MDI) regimen, the pump delivers pre-programmed doses, known as basal rates. These rates can be altered electronically by depressing keys on the pump and can be preset to change automatically at any time in the day.2 For example, a lower rate at night to avoid hypoglycaemia, a higher rate at dawn to elevate fasting hyperglycaemia, and according to activities a varied rate during the day. To reduce the risk of hypoglycaemia, basal rates of insulin can be reduced during and after exercise and increased to avoid hyperglycaemia during illness and stress.2
Insulin bolus doses are activated by the patient before eating or to correct blood glucose levels by keying in the required insulin dose according to what has been consumed.2
Who would benefit from an insulin pump?
Evidence from meta-analysis of randomised control trials found insulin pump therapy, when compared to MDI, can improve glycaemic control and significantly reduce hypoglycaemia.3 Other benefits include less blood glucose variability,4 a reduction in the dawn phenomenon,5 reduced insulin dosage,6 and quality of life and satisfaction improve with the insulin delivery system.7
In light of the evidence, the National Institute for Health and Clinical Excellence (NICE) published a review and re-appraisal on CSII, and recommend this treatment as an option in adults with type 1 diabetes if attempts to achieve a target HbA1c levels with multiple daily injections (MDI) result in disabling hypoglycaemia or HbA1c levels remained high on MDI (≥8.5%) despite a high level of care.8
This guidance should increase referrals for a trial of insulin pump in this population but currently insulin pump provision in the UK is low when compared to other European countries.9 As a consequence, diabetes teams are developing pump services locally, and specialist nurses are well-placed to champion this technology as they frequently lead on insulin pump initiation and education.10
A meeting with a specialist nurse before starting an insulin pump is an opportunity to ensure the patient is ready to start and understands the advantages and challenges they may face. Although it is not easy to predict who will gain the most benefit from an insulin pump, it usually works best in patients who are open to trying technology.11 Other characteristics which predict success include: acceptance of their diabetes; willingness to discuss their insulin pump with others; motivation to use technology; and realistic expectations of what the pump can offer – for example they acknowledge the insulin pump is not a cure. If patients are committed and motivated to use their pump correctly and apply pump safety rules this therapy can be used successfully by all age groups and people with a wide range of educational attainment and disability.12-13
Attention to what patients expect from a pump is crucial as beliefs about how insulin pumps work vary. Anecdotally, some believe this technology will require little self-management, such as capillary blood glucose monitoring and estimating of carbohydrate eaten. Others inaccurately assume the pump will automatically know when their blood glucose levels are too low or too high and the pump will automatically give insulin to rectify the problem. Others believe they do not possess the technological skills to be able to operate and manage an insulin pump and do not relish the idea of been physically attached to machinery 24 hours a day. An opportunity to touch and operate insulin pumps and infusion sets and cannulas helps to dispels misconceptions and reinforces realistic expectations.12
As well as reducing hypoglycaemia and preventing or slowing the progression of long-term diabetic complications3 it is accepted there are other advantages of using an insulin pump.7 These include improvements in quality of life and well-being as a result of having increased flexibility around every day activities such as eating, sleeping, and managing unpredictable physical activity.7 Not having to inject every day and being able to eat less, or not at all, can be life changing.7 It is suggested the reason for this is that the tiny precise doses of continuous rapid acting insulin delivered by the insulin pump are more consistently absorbed than a large depot from injections which may not be absorbed, erratically causing blood glucose levels to run low or high for several hours.2
Common challenges facing people revolve around disguising the device, changing the cannula, and being motivated to check the infusion set and pump regularly. If patients are prepared to monitor blood glucose four to six times a day, be alert to pump alarms and change their insertion cannula every third day the risk of ketoacidosis and site infections are minimised.2
Once the patient wishes to proceed, the pump can be ordered. At a local level choice may be restricted to certain models, but the patient’s ability to see the screen and the level of dexterity needed to manipulate the pump needs to be considered as part of the pre-assessment process.
Starting an insulin pump
Nurses and dieticians typically take the lead in initiating insulin pump therapy. This process requires meticulous planning and is staged over two or three weeks. To maximise a successful transition to the insulin pump, patients are encouraged to reduce their work commitments, involve their family, avoid strenuous exercise and long distance travel.2
Insulin pumps are generally started in an outpatient setting either in groups or individually. Group starts of four, using the same pump brand, are popular in larger centres.2 The advantage of this approach is that patients, familiar with structured diabetes education programmes, welcome the opportunity to share experiences with peers. In a resource-limited environment, pump services can offer a standardised approach that enables more people to start on the pump at one time.14
One approach is to schedule three four-hour group visits, one week apart. Deliberately arranging these for a Monday allows the first five days on the insulin pump to be during the week.14
Objectives which underpin patient education when starting an insulin pump include: setting up and using this technology; choosing the initial insulin settings; inserting a cannula and wearing the pump with saline before going live with insulin in the pump; applying insulin pump principles; and knowing how to troubleshoot.14
Setting up and using the pump technology
A hand’s-on approach, which enables the patient to handle the pump and insert the correct setting, can quickly eliminate anxiety and raise confidence. Patients quickly recognise that insulin pumps are intuitive and no more difficult to use than a mobile phone. The company handbooks and websites supplement this education.12
Choosing the initial insulin doses
On an insulin pump, patients require less total daily insulin. Therefore the total daily insulin dose is typically reduced by 20 percent. Thus, a patient on 55 units can be started on 80% of 55 units, which equals 44 units of insulin in 24 hours on the insulin pump. To work out the basal rate, 50% of the new pump total daily dose is given as a basal. In this example 44/2 = 22 units divided by 24 results in a basal rate of 0.9 units each hour for 24 hours.2
Using the bolus pump features
To ensure patients understand how to give a bolus insulin dose, basic bolus features are taught. This requires patients to accurately estimate the carbohydrate content of their food and to carry out a manual bolus. Patients usually begin by estimating that 10 grams of carbohydrate eaten will need 1 unit of insulin bolus. Pumps now all have features which calculate the bolus insulin based on input from the patient of the actual pre-meal and the target blood glucose levels, the intended carbohydrate intake in the meal, the insulin to carbohydrate ratio, and the ‘insulin on board’ or active insulin. Whilst not suitable for all parents, bolus calculators have been found to reduce pre and post meal blood glucose levels and the number of correction doses needed compared to manual methods of bolus estimation.2
Inserting the cannula and wearing the pump with saline
Although pump saline starts are not compulsory, anecdotally patients usually welcome the opportunity to spend the first week living with their pump and deciding the best place to site the cannula. To avoid problems switching to insulin, patients usually go live with insulin in the morning of the second group session.
Insulin pump principles
Hypoglycaemia treatment, troubleshooting unexplained hyperglycaemia, and caring for the cannula site are three principle patients need to learn in the first few weeks. As there is less circulating basal insulin, episodes of hypoglycaemia require less treatment to normalise the blood glucose level. To avoid over-treating, hypoglycaemia patients are taught to give 15 grams of quick-acting glucose (e.g. 100ml Lucozade) and then to recheck the blood glucose level in 15 minutes.12
Patients are advised to check the pump and infusion set if blood glucose levels above 14mmol/l occur. Unexplained, elevated blood glucose levels are usually related to the infusion set cannula being bent, blocked, or left in situ for longer than three days. Unexplained hyperglycaemia also occurs if the pump is disconnected from the cannula, there is air in the infusion set, or if out-of-date insulin is used. To prevent ketoacidosis urine or blood, ketones are checked and insulin is given either via an insulin syringe or pen device rather than the pump. It is then advised to change the infusion set and cannula before restarting the pump.
Skin care is important. If the cannula is not changed every three days, there is a risk of lipohypertophy, skin infections at the cannula site, and a deterioration in glycaemic control.12
Patients are taught to be alert to alarms which are usually triggered when the battery and insulin reservoir are low. Modern insulin pumps are robust and rarely fail, but if they do the patient will return to MDI insulin regimen until the pump company supply a replacement.
In the weeks and months after starting on the insulin pump, patients will need daily and then weekly telephone or e-mail contact with the nurse or dietician to establish the correct basal rates, and to fine-tune blood glucose levels in response to a whole range of activities which will impact them, from exercise, to stress, illness and menstruation.2,12
In summary, specialist nurses, as part of a multidisciplinary specialist team, are well-placed to educate people with type 1 diabetes to use insulin pumps. Their expertise in type 1 diabetes, structured type 1 education, and knowledge of blood glucose meters lends itself well to providing the continuity and the hands-on knowledge patients need to grasp the practical and emotional aspects required to safely manage a technology which, if used correctly, can reduce hypoglycaemia, improve glycaemic control and transform quality of life.
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