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Pediatric PumpsBarriers and BreakthroughsFrom the University of Colorado Health Science Center, Barbara Davis Center for Childhood Diabetes, Denver, Colorado. Correspondence to Susan Owen, RN, CDE, University of Colorado, Health Science Center, Barbara Davis Center for Childhood Diabetes, 4200 East 9th Avenue, Box B140, Denver, CO 80262.
For the first time, standards of care pertaining specifically to children and adolescents with type 1 diabetes have been published.1 These standards, based primarily on expert opinion, include age-specific glycemic and glycosylated hemoglobin (A1C) goals that balance the desire for good glycemic control with the unique risks of hypoglycemia in children (Table 1). These standards are indeed challenging goals. The question is, What treatment strategies can accomplish this? One approach, the use of insulin pumps in pediatric patients, has increased significantly in the past several years.2
Continuous subcutaneous insulin infusion (CSII) can be initiated and used effectively both in children and in adolescents with type 1 diabetes. The results of clinical trials have shown that metabolic control in children and adolescents was better with CSII than with multiple daily injection (MDI) therapy. In a study of individuals aged 8 to 21 years with type 1 diabetes who were not well controlled with basal insulin alone, switching to CSII therapy resulted in a significant reduction in A1C levels (from 8.1% to 7.2%) after 16 weeks but did not significantly change when switching to MDI therapy (A1C decreased from 8.2% to only 8.1%; Figure 1). The total daily insulin dose also decreased significantly in patients treated with CSII (1.4 U/kg at baseline vs 0.9 U/kg at 16 weeks) but not in patients treated with MDI therapy. Fasting self-monitored blood glucose levels were similar in both groups, while lunch, dinner, and bedtime levels were significantly lower in the CSII group.3
The same concept of switching to CSII therapy was evaluated in young children (younger than 4 years) and showed that patients had better metabolic control and less hypoglycemic episodes after switching from MDI to CSII therapy. Among children treated with CSII, A1C levels significantly (P < .001) decreased from 9.5% to 7.9% (Figure 2).4 Another study in very young children (age range, 1.4-6.9 years) showed that glycemic control was better after 12 months of CSII when comparing values before and after starting CSII therapy. Mean A1C levels decreased from 7.4% to 7.0% after 12 months of CSII therapy and continued to improve even after 4 years of CSII therapy (Figure 3).5 Thus, CSII therapy is a durable and effective means of optimizing glycemic control in children and adolescents with type 1 diabetes.
Anytime control is tightened up and significant decreases in A1C levels are achieved, the development of hypoglycemia can be a worry. One can be reassured that blood glucose levels are generally more stable on pump therapy than with insulin injection regimens, resulting in fewer hypoglycemic episodes. In the study previously described of children younger than 4 years, severe hypoglycemic episodes significantly (P < .05) decreased from 0.52 to 0.09 episodes per month when switching to CSII therapy. The frequency of parental contacts with health care personnel also declined by 80% from once every 5.9 days to once every 46.3 days (P < .01).4 Similarly, the rate of severe hypoglycemia was also reduced when comparing children on CSII therapy with those on MDI therapy. Furthermore, children who received daytime care from paid caregivers (n = 26) experienced significant reductions in A1C levels and frequency of hypoglycemic events (Figure 4).5 Likewise, in teenagers, the rate of severe hypoglycemic events was significantly (P = .01) reduced by almost 50% in the CSII group, despite lower A1C levels in CSII-versus MDI-treated patients (Figure 5).6
Patient Selection Criteria at the Barbara Davis Center Table 2 lists criteria for patients who would be appropriate candidates for pump therapy. These criteria are discussed in more detail below.
Both the Family and the Patient Are Interested in Insulin Pumps Families generally prefer pump therapy to MDI therapy and may refuse to consider a return to previous modes of insulin administration.4 A recent study showed that the frequency of parental stress in managing children with type 1 diabetes was less in children using pump therapy than in those taking injections.7
Patients Are Candidates for Pump Therapy if They Require 4 or More Daily Injections or if They Test Blood Glucose Levels More Than 4 Times Daily
Other Criteria for Insulin Pump Therapy Include Failure to Achieve A1C Goals, Frequent Hypoglycemia, and Erratic Eating/Lifestyle Patterns
Frequent Episodes of Diabetic Ketoacidosis Make a Patient a Candidate for Insulin Pump Therapy
A stepwise approach is used at the Barbara Davis Center to initiate patients, along with their families, to the intricacies of insulin pump therapy. This approach starts at a routine visit to determine if the pump is appropriate. At this visit, either the patient, their family, or the provider should initiate the discussion about changing treatment strategies. The family meets with the physician, dietitian, nurse, and social worker to assess what is needed to prepare them and their child to start CSII. If the evaluation results in a positive assessment, the patient and his or her family will be invited to a session that introduces the pump. In this session, the advantages and disadvantages of insulin pumping are reviewed, and attendees can actually see and begin to work with infusion sets and the pump to familiarize themselves with the device. The next step is a pump initiation class. Before attending this class, most patients should be carbohydrate counting; however, half of the pump initiation class is devoted to reviewing and documenting the patient's ability to count carbohydrates, as well as introducing the documentation required for pumping (eg, how to handle highs and lows, the development of school care plans, etc). Patients then return for the saline pump start session. This introduces them to the basics of working the pump. If the patient is a very young child, the parent may be asked to wear the pump and participate more actively in this session. Two days to a week later, patients return for their insulin pump start, and the pump is loaded with insulin. The process is reviewed, and the patients are now on pump therapy. The physician follows them for the first week on a daily basis. During the following week, patients may transition from the physician to a nurse, and contact is made usually every other day and then every week thereafter for a period of time. Last, they are invited back for an advanced pump class. This is where they learn all of the more sophisticated functions of the pump, such as alternate basal patterns, temporary basal rates, and dual-wave bolusing. The entire process of initiating insulin pump therapy takes 3 to 6 months.
Pumps use predictable, rapid-acting insulin analogs (eg, insulin aspart, insulin lispro). All food intake (primarily carbohydrates) is covered by insulin boluses given by the user, and normal blood glucose levels are maintained at other times by continuous delivery of basal insulin. The first step is to determine how much insulin to use in the pump. Initially, at the Barbara Davis Center, 70% of the total daily dose of insulin prepump therapy is used. Half that amount is the initial basal dose, which is divided over the 24-hour time period. The other half will be used as bolus dosing for carbohydrate intake. Basal rates can be set in 3-hour increments: 12:00 AM, 3:00 AM, 6:00 AM, 9:00 AM, 12:00 PM, 3:00 PM, 6:00 PM, and 9:00 PM. This will help the physician work with the patient to titrate the basal insulin over the next week. It is much easier for the physician to tell patients and their families to adjust up or down in one certain period of time rather than trying to walk them through how to set a new time into their basal patterns over the telephone. The nice thing about basal rates is that they can be adjusted up and down for hormonal output. In prepubescent children, the basal rates between 9:00 PM and 12:00 AM may be increased to compensate for an increase in growth hormone. In adolescents, the basal rate between 3:00 AM and 7:00 AM may be increased to combat hormonal output and the "dawn" phenomenon. Parents should be made aware of these modifications during the pump initiation class so that they are not alarmed.
Alternate patterns can be programmed into insulin pumps to account for days of different activities (eg, gym days vs nongym days or school days vs weekends) or physical situations (eg, menses, extended illnesses, etc). Exercise can result in delayed hypoglycemic episodes, which can be corrected for with the insulin pump. In a study of children that compared days of moderate exercise between 4:00 PM and 5:15 PM with days of no activity, blood glucose levels were lower on active days.10 Even after the immediate exercise period, there were periods of delayed hypoglycemia, sometimes as late as midnight (Figure 6). These findings support the concept that postexercise overnight hypoglycemia is common in children with type 1 diabetes. This also emphasizes the importance of modifying diabetes management, especially prior to bedtime following moderate-to-intense afternoon exercise to reduce the incidence of nocturnal hypoglycemia. If blood glucose levels increase 1 to 2 hours after exercise, the patient was probably insulin deficient during the activity. If the patient disconnected prior to exercise, he or she may need to administer a bolus before the activity, consisting of one half to the full amount of the anticipated missed basal insulin. If the blood glucose level is slightly elevated right after exercise but at target level 1 to 2 hours after exercise with no correction, the patient is at goal. Making use of alternative basal patterns with the insulin pump works well to avoid delayed hypoglycemia. Tips on modifying insulin during exercise are summarized in Table 3.
Insulin-to-carbohydrate ratios are used to cover glycemic rises due to food intake. The correction bolus is an insulin dose taken to reduce high blood glucose levels. It is based on the insulin correction factor (also called the sensitivity factor) and the correction bolus blood glucose target. To calculate the insulin-to-carbohydrate ratio, the "Rule of 500" is used, which is the total daily insulin dose divided into 500 to determine starting carbohydrate ratios. The dietitian reviews diet records (3 days' worth are reviewed at the Barbara Davis Center). It is often found that different ratios may be needed depending on the time of day. Prepubescent children may need a higher ratio in the evening, while pubescent children may need a higher ratio in the morning. The efficacy of this is tested by evaluating a premeal glucose level that is within target, followed by a low-fat, set-carbohydrate meal (frozen low-fat entrees work well), then testing blood glucose levels 2 hours after the meal. If at target, then the carbohydrate-to-insulin ratio dose is valid. This information is summarized in Table 4.
Correction bolus sensitivity and target ranges are shown in Table 5. The correction factor is the amount (mg/dL or mmol/L) by which blood glucose levels are lowered with 1.0 U of rapid-/short-acting insulin. At the Barbara Davis Center, 1700 is used as the value to divide the total daily dose. That approach is anecdotal, but it has been found to work well (other groups use 1500 or 1800). Children tend to have different sensitivity factors based on the time of day. Typically, 3 different target ranges are set. Since the pump's clock starts at midnight, one is set for midnight until the time the child usually wakes, one for waking until bedtime, and a third for bedtime until midnight. This is tested by giving the high blood sugar correction at a time when the child is consuming no food and he or she just needs insulin to correct for a high and then testing 2 hours later to assess whether the patient is in target.
Children occasionally forget to administer bolus insulin. It has been shown that A1C levels in adolescents who used insulin pumps correlate with the number of missed meal insulin boluses. Those who missed 1 or more boluses had higher A1C levels compared to those who did not miss doses (8.8% vs 8.1%). Those who did not miss meals also tested more frequently and also administered a bolus before each meal.11 Diabetes educators and families need to help children and adolescents avoid missed boluses. This can be accomplished with the use of reminder alarms or reminder signs (at the Barbara Davis Center, a Pink Panther sign is used that says, "Food in mouth? Hand on pump."). Reminder alarms can be set for 30 minutes after the time the child usually eats his or her meal. Patients should be taught to bolus at least a portion before meals and to bolus for all carbohydrates, except those taken to treat hypoglycemia. Furthermore, parents should be instructed to review the child's bolus history every evening. It is helpful if the child develops good habits. It is recommended that patients key in their carbohydrate counts every time they bolus (no matter how low the grams of carbohydrates they are eating, with the exception of treatment for hypoglycemia). In addition, adult supervision (or the threat of it) is helpful. Children may forget to bolus their lunch meals during the school day. Sometimes being reminded that they need to bolus or that they will need to go to the nurse's office every day is enough to improve their habits.
Dual-wave boluses can be used to better match food absorption and insulin delivery, especially after high-fat meals (eg, fast food). Treating postprandial hyperglycemia with dual-wave insulin delivery may also help manage chronic hyperglycemia in patients with diabetes.12 A dual-wave bolus is the combination of a normal bolus to deal with the carbohydrate that is absorbed immediately, paired with an extended- or square-wave bolus to handle the prolonged glycemic excursion that is going to occur from the delay in carbohydrate absorption in the presence of fat. This concept was tested by Chase and colleagues.13 Children were fed a high-fat meal (pizza, tiramisu, and cola) for 4 weekends in a row. Different boluses were evaluated each weekend: 1 normal bolus, 2 normal boluses, 1 square-wave bolus, or 1 dual-wave bolus. Use of a dual-wave bolus of 70% upfront and 30% over the next 2 hours was the most effective in dealing with that meal. Similarly, in another recent study, the use of a dual-wave bolus extended over an 8-hour period following a pizza meal resulted in significantly fewer post-prandial hyperglycemic events in the late postprandial period (8-12 hours) without any increased risk of hypoglycemia.14
Inserting an infusion set with minimal needle fear is an important opportunity to interact with the patient. The infusion set can be inserted in the subcutaneous tissue of the abdomen, thigh, arm, or buttocks. Choose an appropriate infusion set and site by doing a gentle pinch test. If a little bit of fat can be pinched up, then the site is a viable option for set insertion. If a patient's body mass index (BMI) is less than 18, a Silhouette© Infusion Set is appropriate. Sometimes heavy, athletic, high school males can have high BMIs because of their muscle mass but have little fat to pinch. In this scenario, a Silhouette© Infusion Set is also used. Tips on inserting and wearing insulin pumps are summarized in Table 6.
In toddlers, the buttocks or thighs are the preferred sites; Quick-sets© Infusion and Silhouette sets work well in this age group. In school-aged children, the abdomen and hips are the favored insertion sites, often using a 6mm Quick-set© or a Silhouette© Infusion Set. The buttocks may also be a site used by school-aged children. Teens use the gamut, all 4 sites (abdomen, thigh, arm, and buttocks) and, unless they are very lean, can use every set that is available. Children who are very active in sports may find that the sets that go in at an angle adhere better. To make pump placement easier for pediatric patients, desensitization techniques are used. Breathing techniques, distraction, and visualization are all helpful; bubble blowing is a really nice trick for this. Topical anesthetics are also used, such as EMLA© (AstraZeneca, Westborough, Mass), generic lidocaine 2.5%/prilocaine 2.5% crème, or L.M.X.4© (Ferndale Laboratories, Ferndale, Mich). Use of an autoinserter can also make insertion less painful. The insertion devices that come with the pumps can make it easier to insert the cannula into the skin. It is important that the insertion set remains securely in place as children go through the activities of the day and sleep at night. Some methods to improve adhesion include the use of wipe-on preparations, such as antiperspirant, Skin Prep protective wipes, Skin Tac-H, Bard Protective Barrier Film, tincture of benzoin, and mastisol liquid adhesive. Similarly, recommendations to ease removal of the set include water, baby oil, UniSolve© Remover, and Detachol© Adhesive Remover. For children, wearing the pump can be a source of anxiety. How will it stay on while doing a range of activities? How will it look? There are various pump accessories available through Web sites that are both practical and fashionable. Pump accessories come as shorts, shirts, boxers, bras, sports pouches, and even garters.
Check for ketones. If unexplained hyperglycemia occurs, checking for ketones is recommended. Blood or urine ketone testing should be done if the blood glucose levels are greater than 300 mg/dL (16.5 mmol/L) or if 2 blood glucose tests are greater than 240mg/dL (13.2 mmol/L). It is recommend that every child at the Barbara Davis Center who is on an insulin pump also know how to use a blood ketone meter, such as the Precision XtraTM Blood Ketone Meter. Children prefer to test for blood ketones while at school, rather than urine ketones (they tend to find it more discrete). Other scenarios in which it is recommended that patients test for blood ketones are when the child is unable to urinate or a urine test has come back positive. The blood ketone test also offers greater accuracy. If the patient is ketone positive, the patient should self-administer an insulin injection and be counseled to drink plenty of fluids. Because one cause of unexplained hyperglycemia and ketones in insulin pump users is a blockage of the internal cannulae, a set change and retesting of blood glucose levels every 2 hours with subsequent correction dosages as needed are recommended. Check time and basal settings. Other reasons for high blood glucose readings may be alarms that erase the basal rates. A child may hastily clear the alarm without reprogramming the basal rates and resetting the time and date. The new pumps are great at telling them right on the screen to reset their basal rates, even when they may not always remember to do so. The newest generation of the Medtronic Pump has a user-setting feature that allows users to save their user settings. Then, if they get an alarm such as this, it is really easy to go back in there and hit "Restore Settings," and it will reprogram all of those settings for them. Check connections/bubbles. Pediatric patients are asked to suspend insulin delivery when disconnecting from the pump. The alarm that is triggered in the suspend mode will help to remind them to hook back up. In addition, children are so active that sometimes bubbles accumulate in the line and interfere with insulin delivery. Children should check for bubbles several times a day and clear them out if they are present.
Children with diabetes sometimes face problems in obtaining the care they need in schools and day care centers. However, several federal and state laws provide protections to children with disabilities, including children and teens with diabetes. These children must have full and equal access to public education. Students with diabetes are entitled to accommodations and modifications that are necessary for them to stay healthy at school and have the same access to an education as other students do. The school nurse in addition to the parents and the child's health care team should prepare a plan that outlines how the child's needs will be met. The plan should identify school staff responsible for performing diabetes tasks and making sure the plan is followed. Any changes to the plan should be made only with the parents' consent. Ideally, the plan should be updated every year. A sample plan is available at www.BarbaraDavisCenter.org, and a sample 504 plan is available at the American Diabetes Associations Web site (www.diabetes.org). Other standard recommendations include the following:
Insulin pumps are a very effective way to manage diabetes in children and adolescents. When disease and pump management are appropriately individualized, CSII therapy can help children with diabetes achieve and sustain glycemic control. Lifestyle flexibility, quality of life, and independence can begin in childhood and be maintained through adulthood with the use of insulin pumps. As with all diabetes management issues, individualized treatment plans that consider the needs of the patient as well as those of the family are the most likely to be successful.
The Diabetes Educator, Vol. 32, No. 1,
29S-38S (2006)
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