Insulin Pump:

Continuous Subcutaneous Insulin Infusion (CSII)


 
 

"Ö the pump improves the patientís quality of life."
 
 
 
 
 
 
 
 
 
 

What is it?

An insulin pump is a device the size of a pager that injects insulin continuously under the skin to help keep blood glucose levels near normal. As an alternative to multiple daily injections for people with type 1 diabetes, the insulin pump allows the patient to manage blood glucose levels and obtain tighter control. By programming the pump, the diabetic is able to regulate insulin flow for changes such as varied schedules, changing activity levels, changes in diet, changes in blood glucose levels, etc. The insulin pump is an open loop system. This means that there is no glucose sensor and no automatic feedback that releases insulin in response to increased blood glucose levels. See home.twcny.rr.com/bobscorner/pumping.htm for pictures of two different models.
 
 

How does it work?

The continuous subcutaneous insulin infusion system consists of a pump and an infusion set. The pump unit houses the syringe filled with short-acting insulin (Regular, Humalog). This insulin is injected continuously into the body through a thin tube and catheter that is inserted under the skin and secured with tape. The infusion set consists of a plastic infusion tubing joined to a needle or plastic cannula. The pump is worn on a belt, in a pocket, tucked in clothing, or attached to the arm or thigh by an elastic band.

The user programs the pump to deliver a continuous rate of insulin (basal rate) which mimics the pancreasí usual insulin secretion. Because the bodyís insulin requirements vary throughout the day, the basal rate injected should also vary. For more information on determining basal rates, see www.diabetes.org/am98/ChicagoChronicles/monday/mellitus.asp. When blood sugar levels are higher than desired, the user presses buttons on the pump to deliver a larger dose (bolus). A bolus is also used at mealtime and when snacking. The bolus is calculated based on carbohydrate intake from the meal or snack. When correcting for high blood sugar levels, the bolus amount depends on the amount of insulin required to bring the blood glucose back into the normal range. The user can also program the pump to temporarily increase or decrease the basal rate due to illness or exercise.

Other Considerations

  1. Patients using the pump must be willing and able to monitor blood glucose levels at least 4 times a day. This allows the patient to regulate the basal rate and bolus amounts based on the levels obtained from monitoring. By keeping a record or log of blood glucose data, the patient can keep a tighter control on his/her diabetes.
  2. Patients should consult with their doctor to set a blood glucose target value in order to reduce the risk of hypoglycemia. If the value is set too low, intensified insulin treatment may result in serious hypoglycemia, especially in those patients who do not experience symptoms of epinephrine release when this occurs.
  3. Patients using pump therapy must perform meticulous skin care at injection sites to prevent infection.
  4. Patients must perform self-monitored glucose levels to correct for plugging or leaking of infusion sets. If these problems are not detected, ketoacidosis may occur. However, they can be corrected by adjusting the infusion set.

Advantages and Disadvantages of CSII

Advantages:

Insulin pumps are able to deliver insulin to the body at a continuous basal rate as well as in boluses. By using this method of diabetes treatment, the body is receiving insulin in a manner that simulates the way the pancreas delivers insulin to a non-diabetic person. CSII patients are able to enjoy greater flexibility in their lifestyle due to small insulin changes throughout the day (Boland, Ahern, & Grey, 1998). Insulin pumps are more effective than the 2 or 3 injections per day method. Because of the improved metabolic control, patients using CSII prevent chronic complications often seen in diabetic patients (Savinetti & Bolmer, 1997). These results were obtained in the Diabetes Control and Complications Trials (DCCT) in 1993. For information on the DCCT results, see www.minimed.com/files/gd_cntrl.htm and www.diabetes.org/DiabetesSpectrum/97vl10n4/pg259.htm

Disadvantages

Because the insulin pump is an open loop system, there is no negative-feedback component to monitor blood glucose levels and regulate insulin release. There is also an unpredictable variability in absorption from subcutaneous sites. Due to this lack of efficacy, the patient is required to have an individualized target blood glucose value and to perform frequent self-monitoring of blood glucose levels.

Complications

  1. There is an increase in frequency of infections at the infusion site by Staphylococcus aureus. The infusion set should be replaced if infection is present and/or if there is an unexpected increase in blood glucose level.
  2. Ketoacidosis is a common occurrence if there is an obstruction of tubing or leakage from the infusion set. Blood glucose levels should be monitored 4 times a day. If blood glucose is 240mg/dl, the infusion set should be checked. Upon rechecking in 1 to 2 hours, if still elevated, the set should be changed.
  3. There is an increase incidence of hypoglycemic reactions due to intensive insulin therapy. However, it is less frequent than with multiple injection therapy.

Cost

There are two suppliers that make insulin pumps: MiniMed Technologies and Disetronic Medical Systems. The retail price for most models is about $4500 with infusion set and supplies at about $120/month. Insurance companies vary at what pump and supply costs they cover.

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Reference/Related articles:

Boland, E., Ahern,J., & Grey, M. (1998, Jan-Feb). A primer on the use of insulin pumps in adolescents. Diabetes Educator, 24, 78-87,89.

Savinetti, R.B. & Bolmer, L. (1997, March). Understanding continuous subcutaneous insulin infusion therapy. American Journal of Nursing, 97 (3), 42-29.
 
 
 
 

Implantable Insulin Pump

What is it?
 

An implantable insulin pump is a device surgically implanted under the skin of the abdomen that delivers insulin continuously into the abdominal cavity to help keep blood glucose levels near normal. Like the external insulin pump, it is an open loop system that neither monitors nor responds to blood glucose levels. As an alternative to multiple daily injections for people with type 1 diabetes, the insulin pump allows the patient to manage blood glucose levels and obtain tighter control. See www.dml.georgetown.edu/depts/pediatrics/diabetes/new_devices.htmlfor the history of the miniaturized pump.
 
 

How does it work?

The implantable pump is comprised of a casing, electronics/communication components, an insulin reservoir, a pump, a battery, a catheter, and insulin. A device similar to a TV remote control is used to communicate with microchips inside the pump. By holding the remote control against the abdomen, the user programs the pump to deliver insulin at a continuous rate (basal rate) and at mealtimes (bolus). The catheter carries the insulin to the abdomen site where it is absorbed by the liver. The insulin reservoir can hold an equivalent of six vials of regular insulin which can last up to three months. The battery lasts only three years.

Because of the threat of insulin overdose, the pump has a safety device that sounds an alarm when something is wrong (e.g. low battery). The pump shuts down if there is a system error. To facilitate refilling with insulin, the pump has a negative pressure reservoir that pulls the insulin in. Taking only 15 minutes, the refill procedure involves using a syringe to pull the old insulin out and put the new insulin in. This procedure, done in the doctorís office, is done every 6 to 12 weeks, depending on how much insulin the person needs.

Advantages and Disadvantages: In a research study conducted at seven V.A. Medical Centers, C.D. Saudek (1996) found that the implantable insulin pump offered several advantages over the multiple injection therapy with less significant disadvantages.

Advantages

  1. There is better absorption with the implantable pump resulting in fewer daily blood sugar fluctuations. The decrease in hyperglycemic reactions (dizziness, trembling, headache, nausea, rapid heartbeat) points to a more precise method of treatment. By delivering insulin deeper into the abdomen rather than just under the skin, there is better absorption by the liver.
  2. There is less weight gain for those using the implantable pump. Those using the multiple injection therapy have a tendency to gain weight. When blood glucose levels are poorly controlled, glucose and calories are excreted in the urine. However, the implantable pump seems to mimic natural insulin production without the side effects of multiple injection therapy.
  3. The implantable pump provides a more convenient method of insulin administration without needles. By avoiding daily injections, the pump improves the patientís quality of life. Insulin is automatically delivered to the body by signaling the pump with a remote control device.

Disadvantages

  1. The implantable pump is more expensive than other methods of diabetes treatment.
  2. Some implantable pumps clogged requiring them to be cleaned out. However, researchers are reformulating insulin to prevent this problem.
  3. Because the implantable pump is an open loop system, there is no negative-feedback component to monitor blood glucose levels and regulate insulin release.

Complications

F.L. Dunn (1997) reports the implantable pump to yield fewer episodes of severe hyperglycemic reactions. However, as with the external pump, there are still incidences of these reactions. Therefore, the patients using this pump need to do frequent self-monitoring of blood glucose levels to avoid them.

Cost

The implantable pump has not been approved by the FDA yet and therefore, not commercially available in the United States. Awaiting FDA approval, these pumps are being developed by MiniMed Technologies in Sylmar, CA. However, there is an expected price tag of $10,000, which does not include the cost of implantation surgery.

Research gaps and inconsistencies:

The lead author of the study, C.D. Saudek, is Director of the Hopkins Comprehensive Diabetes Center where the pump was designed. The fact that the author is director of the developing company leads to questions of bias. Another inconsistency involves the question of whether the pump will be covered by insurance companies. Without insurance coverage, the implantable pump will not be available to many consumers.

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Related articles:

www.diabetes.com/FEATURES/FST10024.HTM

http://www.intelihealth.com/IH/ihtIH?d=dmtContent&c=189065&p=~br,IHW|~st,408|~r,WSIHW000|~b,*|

References:

_____. (n.d.).Implantable pump sticks it to the needle. [On-line]. Available Internet: www.diabetes.com/FEATURES/FST10024.HTM.

Dunn, F.L., Nathan, D.M., Scavini, M., Selam, J.L., & Wingrove, T.G. (1997 Jan). Long-term therapy of IDDM with an implantable insulin pump: the Implantable Insulin Pump Trial Study Group. Diabetes Care, 20, 59-63.

Nathan, D.M., Dunn, F.L., Bruch, J., McKitrick, C., Larkin, M., Haggan, C., Lavin-Tompins, J., Norman, D., Rogers, D., & Simon, D. (1996 April). Postprandial insulin profiles with implantable pump therapy may explain decreased frequency of severe hypoglycemia, compared with intensive subcutaneous regimens, in insulin-dependent diabetes mellitus patients. American Journal of Medicine, 100 (4), 412-417.

Saudek, C.D., Duckworth, W.C., Giobbie-Hurder, A., Henderson, W.G., Henry, R.R., Kelley, D.E., Edelman, S.V., Zieve, F.J., Adler, R.A., Anderson, J.W., Anderson, R.J., Hamilton, B.P., Donner, T.W., Kirkman, M.S., & Morgan, N.A. (1996 Oct 23-30). Implantable insulin pumps vs multiple-dose insulin for non-insulin-dependent diabetes mellitus: A random clinical trial. Department of Veterans Affairs Implantable Insulin Pump Study Group. Journal of the American Medical Association, 276 (16), 1322-1327.

Saudek, C. (1998, June 7). No more injections? [On-line]. Available Internet: http://www.intelihealth.com/IH/ihtIH?d=dmtContent&c=189065&p=~br,IHW|~st,408|~r,WSIHW000|~b,*|