Fluent material handling – with receiver or receiver coacting mea – Processes – Filling dispensers
Reexamination Certificate
2003-03-31
2004-09-07
Scherbel, David A. (Department: 3751)
Fluent material handling, with receiver or receiver coacting mea
Processes
Filling dispensers
C141S018000, C141S021000, C604S183000
Reexamination Certificate
active
06786244
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to devices used to infuse liquid medication into a patient. More specifically, this invention relates to miniaturization of such devices.
DESCRIPTION OF RELATED ART
Insulin dependent diabetes mellitus (IDDM) is caused by the autoimmune destruction of the insulin producing islets of Langerhans in the pancreas. Insulin replacement therapy is the interim treatment for IDDM until such time as islet transplants, stem cell treatments, or other improved treatments become feasible. Insulin lowers the concentration of glucose in the blood, while food—in particular, carbohydrates—raises the concentration of glucose in the blood. The challenge of insulin therapy is to administer food and insulin in a manner that maintains blood glucose concentrations in an acceptable range, avoiding hypoglycemia and hyperglycemia.
Hyperglycemia (high blood glucose concentration) has adverse long-term consequences for the body. These consequences include kidney damage leading to kidney failure, microaneurisms in the retina causing blindness, and the blocking of capillaries in the extremities causing an inability to heal wounds and subsequent gangrene. Hypoglycemia (low blood glucose concentration) has an immediate adverse consequence of reduced brain function that leads to confusion and an inability to reason, remember, or react. In the extreme, hypoglycemia causes seizure, coma, and death.
The first insulin used by diabetes patients was regular insulin taken from beef or pig pancreases. This insulin lasts for about six hours, so that patients were required to inject it three or four times per day. After World War II, longer acting insulin was developed by binding regular insulin to protamine and zinc. Regular insulin dissociates slowly from protamine and zinc, extending insulin action to twelve hours for intermediate acting insulin and twenty-four hours for very long acting insulin. Patients enjoyed reducing injections to one per day, but were required to modify their eating to a snack-all-day regimen to avoid hypoglycemia. The one daily insulin dose was adjusted as needed to reduce the incidence of both hypoglycemia and hyperglycemia.
The development of portable blood glucose meters encouraged the development of more sophisticated insulin therapy regimens. One of these regimens is the split/mixed regiment that consists of two daily doses of mixed regular and intermediate acting insulins taken before breakfast and dinner. These four insulin therapy components are adjusted using blood glucose values measured before each meal and at bedtime. Patients using the split/mixed regimen are required to eat substantially the same meals every day so that the four insulin components may be adapted to the consistent meal pattern over time. Patients on the split/mixed regimen are not only faced with a consistent pattern of what they eat in terms of amount of food, but are also required to eat their meals at particular times. Delay of a meal will result in the patient suffering hypoglycemia
A more recent development in insulin regimen is the basal/bolus regimen, which provides far more flexibility in quantity and timing of meals. The basal/bolus program attempts to emulate the method by which an intact pancreas controls blood glucose. Normally, the intact pancreas produces a steady supply of basal insulin to accommodate the body's basic insulin needs for glucose secreted at a relatively constant rate from the liver. The pancreas handles meals by releasing a sharp impulse of bolus insulin to accommodate a rapidly rising blood glucose resulting from transformation of carbohydrates (and, to a lesser extent, other food items, especially protein) into blood glucose.
In the basal/bolus regimen, the basal insulin releases are emulated by a once a day injection of a long acting insulin, such as Lantus®, a product of Aventis Pharmaceuticals, or Ultralente®, a product of Eli Lilly and Company. Ultralente is sometimes injected twice daily. These long acting insulins provide the body with a relatively constant supply of insulin. The bolus insulin releases are emulated by bolus injections of fast acting Humalog® (lispro), or other fast acting insulin. The amount of fast acting insulin taken in an injection must be proportional to the amount of carbohydrate taken with the meal. Some diabetics are able to further fine-tune the injection by calculating the amount of protein, which has a smaller effect on the rise of blood glucose concentration.
To illustrate the basal/bolus regimen in an example, assume a typical diabetic who requires 0.5 units per hour of basal insulin. This person will need a 12-unit injection of long acting insulin daily to cover his or her basal requirements. Timing of such an injection is not critical, and in fact, the long acting insulin is often mixed with the fast acting insulin in one of the bolus injections. Further assume that this typical diabetic's blood glucose is raised 4 mg/dl (blood glucose concentrations are measured in milligrams per deciliter) for every gram of carbohydrate eaten. This is known as carbohydrate sensitivity. Assume also that a unit of insulin (insulin is measured in “units”) reduces this typical diabetic's blood glucose concentration by 40 mg/dl. This is known as insulin sensitivity. The diabetic sits down at a meal and adds up the total grams of carbohydrates in the meal. Assume the meal consists of 80 g of carbohydrates. The diabetic would compute the increase in blood glucose concentration to be (4 mg/dl/g)*(80 g)=320 mg/dl. The diabetic would then compute the amount of bolus insulin required to accommodate, or “cover” this increase, knowing his or her insulin sensitivity. (320 mg/dl)/(40 mg/dl/unit)=8 units. The diabetic would therefore inject 8 units of fast acting insulin before eating the meal.
In practice, exercise, stress, and even unknown factors cause the above calculations to be only approximations. The diabetic, in his or her basal/bolus regimen, usually also needs to adjust the bolus dose taken based upon a blood glucose reading taken prior to the meal. A typical desired target for a diabetic's blood glucose concentration prior to a meal is 100 mg/dl. “Normal” blood glucose concentration range is 80 mg/dl to 120 mg/dl. A blood glucose concentration of 70 mg/dl or lower is usually considered to be hypoglycemic. A blood glucose concentration of 40 mg/dl is dangerously hypoglycemic and the diabetic is usually seriously impaired when his or her blood glucose concentration is at that level. A sustained blood glucose concentration of 20 mg/dl or lower is considered to expose the diabetic to permanent brain damage.
Suppose that, in the example above, the diabetic's pre-meal blood glucose concentration were 180 mg/dl. The diabetic would recognize that as being 80 mg/dl above the desired concentration of 100 mg/dl. Using the insulin sensitivity in the example, the diabetic would compute the additional insulin required as (80 mg/dl)/(40 mg/dl/unit)=2 units. In the example, the diabetic would then take a 10-unit bolus; 8 for the carbohydrates in the meal, and 2 more to “cover” the fact that the premeal blood glucose concentration was 80 mg/dl above target. If, in the example, the premeal blood glucose concentration were 80 mg/dl (versus a 100 mg/dl “target”), the diabetic would compute a 0.5 unit negative adjustment (80 mg/dl-100 mg/dl)/(40 mg/dl/unit), and thus take a bolus of 7.5 units with the meal instead of 8 units.
Insulin pumps are mechanisms that allow the basal/bolus regimen to be practiced even more effectively. An insulin pump contains a reservoir of fast acting insulin. Insulin is pumped through a tube from the reservoir into the diabetic. A computer within the pump, with which the diabetic interacts, controls the insulin pump. The diabetic programs in a “basal profile” which tells the pump how much of the fast acting insulin per unit time period to infuse into the diabetic. The pump then infuses this amount into the diabetic in a series of small infusions. In the exampl
Huynh Khoa D.
Scherbel David A.
Williams Robert R.
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