DIALYSIS PUMPS

February 8, 2017


I entered the university shortly after Sir Isaac Newton and Gottfried Leibniz invented calculus. (OK, I’m not quite that old but you do get the picture.) At any rate, I’ve been a mechanical engineer for a lengthy period of time.  If I had to do it all over again, I would choose Biomedical Engineering instead of mechanical engineering.  Biomedical really fascinates me.  The medical “hardware” and software available today is absolutely marvelous.  As with most great technologies, it has been evolutionary instead of revolutionary.    One such evolution has been the development of the dialysis pump to facilitate administrating insulin to patients suffering with diabetes.

On my way to exercise Monday, Wednesday and Friday, I pass three dialysis clinics.  I am amazed that on some days the parking lots are, not only full, but cars are parked on the roads on either side of the buildings. Almost always, I see at least one ambulance parked in front of the clinic having delivered a patient to the facilities.  In Chattanooga proper, there are nine (9) clinics and approximately 3,306 dialysis centers in the United States. These centers employ 127,671 individuals and bring in twenty-two billion dollars ($22B) in revenue.  There is a four-point four percent (4.4%) growth rate on an annual basis. Truly, diabetes has reached epidemic proportions in our country.

Diabetes is not only one of the most common chronic diseases, it is also complex and difficult to treat.  Insulin is often administered between meals to keep blood sugar within target range.  This range is determined by the number of carbohydrates ingested. Four hundred (400) million adults worldwide suffer from diabetes with one and one-half million (1.5) deaths on an annual basis.  It is no wonder that so many scientists, inventors, and pharmaceutical and medical device companies are turning their attention to improving insulin delivery devices.   There are today several delivery options, as follows:

  • Syringes
  • Pens
  • Insulin Injection Aids
  • Inhaled Insulin Devices
  • External Pumps
  • Implantable Pumps

Insulin pumps, especially the newer devices, have several advantages over traditional injection methods.  These advantages make using pumps a preferable treatment option.  In addition to eliminating the need for injections at work, at the gym, in restaurants and other settings, the pumps are highly adjustable thus allowing the patient to make precise changes based on exercise levels and types of food being consumed.

These delivery devices require: 1.) An insulin cartridge, 2.) A battery-operated pump, and 3.) Computer chips that allow the patient to control the dosage.  A detailed list of components is given below.  Most modern devices have a display window or graphical user interface (GUI) and selection keys to facilitate changes and administrating insulin.  A typical pump is shown as follows:

insulin-pump

Generally, insulin pumps consist of a reservoir, a microcontroller with battery, flexible catheter tubing, and a subcutaneous needle. When the first insulin pumps were created in the 1970-80’s, they were quite bulky (think 1980’s cell phone). In contrast, most pumps today are a little smaller than a pager. The controller and reservoir are usually housed together. Patients often will wear the pump on a belt clip or place it in a pocket as shown below. A basic interface lets the patient adjust the rate of insulin or select a pre-set. The insulins used are rapid acting, and the reservoir typically holds 200-300 units of insulin. The catheter is similar to most IV tubing (often smaller in diameter), and connects directly to the needle. Patients insert the needle into their abdominal wall, although the upper arm or thigh can be used. The needle infusion set can be attached via any number of adhesives, but tape can do in a pinch. The needle needs to be re-sited every 2-3 days.

pump-application

As you can see from the above JPEG, the device itself can be clipped onto clothing and worn during the day for continued use.

The pump can help an individual patient more closely mimic the way a healthy pancreas functions. The pump, through a Continuous Subcutaneous Insulin Infusion (CSII), replaces the need for frequent injections by delivering precise doses of rapid-acting insulin 24 hours a day to closely match your body’s needs.  Two definitions should be understood relative to insulin usage.  These are as follows:

  • Basal Rate: A programmed insulin rate made of small amounts of insulin delivered continuously mimics the basal insulin production by the pancreas for normal functions of the body (not including food). The programmed rate is determined by your healthcare professional based on your personal needs. This basal rate delivery can also be customized according to your specific daily needs. For example, it can be suspended or increased / decreased for a definite time frame: this is not possible with basal insulin injections.
  • Bolus Dose: Additional insulin can be delivered “on demand” to match the food you are going to eat or to correct high blood sugar. Insulin pumps have bolus calculators that help you calculate your bolus amount based on settings that are pre-determined by your healthcare professional and again based on your special needs.

A modern insulin pump can accomplish both basal and bolus needs as the situation demands.

The benefits relative to traditional methods are as follows:

  • Easier dosing: calculating insulin requirements can be a complex task with many different aspects to be considered. It is important that the device ensures accurate dosing by taking into account any insulin already in the body, the current glucose levels, carbohydrate intake and personal insulin settings.
  • Greater flexibility:  The pump must be capable of instant adjustment to allow for exercise, during illness or to deliver small boluses to cover meals and snacks. This can easily be done with a touch of a button with the more-modern devices. There should be a temporary basal rate option to proportionally reduce or increase the basal insulin rate, during exercise or illness, for example.
  • More convenience: The device must offer additional convenience of a wirelessly connected blood glucose meter. This meter automatically sends blood glucose values to the pump, allowing more accurate calculations and to deliver insulin boluses discreetly.

These wonderful devices all result from technology and technological advances.  Needs DO generate devices.  I hope you enjoy this post and as always, I welcome your comments.

Advertisements

What do you think?

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: