and How to Mimic it with the MiniMed 506 Insulin Pump Using a Square Wave Bolus Mary Jean Renstrom, Mjrenstrom@aol.com v1.01, Jan 12, 1998 This document tells what a square bolus is, how it is used and how to simulate it on a MiniMed 506 insulin pump. ______________________________________________________________________ Table of Contents 1. Introduction 1.1 Acknowledgements 1.2 What is a square wave bolus and why would I use one? 1.3 Disclaimer 2. Which pumps can deliver a Square Wave Bolus? 3. What happens to the basal insulin while the square wave is in effect? 3.1 The MiniMed 507 3.2 The MiniMed 506 4. HOWTO program a Square Wave Bolus with a MiniMed 506 5. Copyright notice. ______________________________________________________________________ 1. Introduction 1.1. Acknowledgements Special thanks to Bob Burnett > for his assistance with this HOWTO. 1.2. What is a square wave bolus and why would I use one? A square wave bolus is an insulin bolus delivered with an insulin pump over an extended period of time. The time range is usually from 1/2 hour to 3 hours. Some pumpers utilize this tool to match the rate of food digestion with the rate of insulin activity by spreading the bolus over the length of time it takes to digest a meal. One way to accomplish this is to deliver a portion (perhaps half) of the meal bolus at the beginning of a meal and then deliver the rest in a square wave over the next two hours or so. Other pumpers use the square wave to reduce the spike in insulin activity. For instance, when blood glucose is a little on the low side at the beginning of a meal, one might wish to deliver the insulin over the next half hour, thus giving the food a chance to start working before the insulin activity peaks. The square wave bolus is useful for lengthy meals or prolonged snacking such as at a reception or banquet; for someone with gastroparesis; or whenever extending the effect of the insulin is desired. This is sometimes referred to as the pizza bolus because the fat in pizza tends to slow down glucose absorption, resulting in a delayed rise in blood glucose. 1.3. Disclaimer The human metabolism varies from person to person and some experimentation may be required to determine what time frame works best for you. The times given in this article are only examples and should be considered as a starting point, not set in stone. You should consult with your physician and health care team when making changes to your insulin regimen. 2. Which pumps can deliver a Square Wave Bolus? The square wave bolus is a feature of the MiniMed 507 pump and can be easily mimicked with a MiniMed 506 pump using the temporary basal rate feature. Other pumps, however, do not have a square wave option and it would be cumbersome, at best, to try to duplicate it. To truly mimic a square wave, the pump must have a temporary basal rate feature which allows the user to specify the length of time for the temporary rate. The Disetronic HTRON V100 and HTRONplus V100 pumps as well as the MiniMed 504 pump handle temporary basal rates in a manner which doesn't allow the user to set the duration. Trying to program a square wave with these pumps necessitates changing the programmed basal rates to an artificial level and then (hopefully) remembering to set them back at the end of the time for the square wave. This is potentially dangerous, as the risk for hypoglycemia is quite high if the user does not remember to, or is unable to, set the basal rate back to normal. If you wish to achieve a square wave effect with these pumps, you could administer several small boluses manually over the desired length of time until the total bolus amount has been given. For example: (Not recommended). If a bolus of six units of insulin were to be administered over a one hour time period, you could program a bolus of one unit every 10 minutes, or, a bolus of one and a half units every fifteen minutes. At the end of one hour, the total six units will have been delivered. 3. What happens to the basal insulin while the square wave is in effect? 3.1. The MiniMed 507 ...automatically continues to deliver the basal insulin while administering a square wave bolus. You only need to include the insulin to cover the food in the square wave amount. 3.2. The MiniMed 506 ...does not automatically add the basal insulin, you must add the basal insulin to the amount for the square wave. This is because the basal feature will be occupied with duplicating the square wave and can't continue to deliver the programmed basal rate. 4. HOWTO program a Square Wave Bolus with a MiniMed 506 Follow these steps to mimic a square wave bolus with a MiniMed 506 pump: 1. Calculate the amount of the desired bolus and decide over what length of time you want it delivered. Add to this the amount of basal insulin which would normally be delivered during this time period. This is the total bolus amount. 2. Divide the total bolus amount by the length of time for delivery, resulting in the amount of insulin per hour. 3. Program a temporary basal rate of the amount figured in step 2 for a duration equal to the desired length of time. Note: You may need to reset the factory settings for maximum basal rates on your pump before beginning this procedure. Refer to your pump users manual for instructions. For example: (Again, this is just an example, your rates and times may vary from this.) Insulin required to cover food intake: 5 units Desired length of square wave: 2 hours Normal basal rate: 0.4 units/hour Total basal insulin for the time period: 0.8 units Total bolus amount: 5.8 units Insulin per hour for square wave: 2.9 units/hour Following this example, you would program a temporary basal rate of 2.9 units per hour for a duration of two hours to mimic the square wave. 5. Copyright notice. Copyright (C) 1998 Mary Jean Renstrom and Insulin Pumpers Permission to use, copy, distribute this document for any purpose is hereby granted, provided that the author's / edi- tor's name and this notice appear in all copies and/or sup- porting documents; and that an unmodified version of this document is made freely available. This document is dis- tributed in the hope that it will be useful, but WITHOUT ANY WARRANTY, either expressed or implied. While every effort has been taken to ensure the accuracy of the information documented herein, the author / editor / maintainer assumes NO RESPONSIBILITY for any errors, or for any damages, direct or consequential, as a result of the use of the information documented herein.