Electronically controlled infusion devices and arrangements

Abstract: A microprocessor controlled volumetric infusion pump is set as to volume and rate of infusion by two digipots (shaft encoders) each having sixteen detented positioned in 360 degrees. The microprocessor is programmed such that the extent to which the parameter is changed for a given rotation of its setting digipot depends on the speed with which the digipot is rotated. For slow or normal rotation, unit change in parameter is produced for each detented position traversed. Faster rotation causes the setting to jump from one to the next of a series of preselected preferred settings, irrespective of the number of detented positions traversed. The direction of rotation determines whether the setting increases or decreases.

Description: This invention relates to electronically controlled infusion devices and arrangements and more particularly to infusion controllers or infusion pump arrangements which may be set to provide a desired volume of fluid to be infused at a desired flow rate as dictated by the needs of a patient under treatment and requiring fluids to be infused intravenously. Examples of such pump arrangements are to be found described in GB-2225065A. As is well-known, medical staff operate under considerable time pressure and one object of the present invention is to provide improved infusion controllers and volumetric infusion pump arrangements which may be set to provide required volumes of liquid to be infused and/or rates of flow relatively speedily and in a manner which tends to reflect the sense of urgency with which medical staff operate. Conventional electronically controlled intravenous infusion apparatus commonly include a manually operable control knob which is rotated by the operator to set at least one infusion parameter of the apparatus according to the extent to which the knob is rotated. According to the present invention, there is provided an electronically controlled intravenous infusion apparatus according to claim 1. Preferably, the apparatus is such that for setting the flow rate said sensing means is responsive to two rates of movement, normal or slow movement and fast movement. Preferably the apparatus is such that for setting the volume-to-be-infused said sensing means is responsive to three rates of movement. Preferably the apparatus is such that for setting the volume-to-be-infused said sensing means is responsive to three rates of movement, normal or slow movement causing incremental setting changes; fast movement causing the setting to jump to the next multiple of 100ml of volume of fluid to be infused and very fast movement causing the setting to jump to the next adjacent multiple of 1000ml of volume-to-infused. Preferably said movement is rotary movement and preferably said control device is a digipot or shaft encoder The invention is illustrated in and further with reference to the accompanying drawings in which:- Figure 1 is a schematic representation of the control panel of one example of electronically controlled volumetric infusion pump arrangement in accordance with the present invention. Figure 2 is a flow chart appertaining to the microprocessor program controlling the flow rate setting of the pump and Figure 3 is a flow chart appertaining to the microprocessor program controlling the volume-to-be-infused setting of the pump. Referring to the drawings, the microprocessor controlled pump (not represented) is as described in detail in our U.K. specification published under serial number 2225065A to which reference may be made for further information. Setting of the flow rate of the pump is provided for by means of a so-called digipot or shaft encoder 1. A digital display 2 is arranged to indicate the flow rate setting achieved as digipot 1 is rotated clockwise to increase the rate or anti-clockwise to decrease the rate. A "confirm" button 3 is arranged, when pressed, to cause the pump to commence pumping at the selected rate, when a "start" button (not shown) is operated, or to change from a previously selected rate to the selected new rate, as displayed on display 2. Adjustment of the volume-to-be-infused setting of the pump is provided for by means of another digipot 4. A digital display 5 is arranged to display the volume-to-be-infused setting achieved as digipot 4 is rotated clockwise to increase the volume-to-be-infused or anti-clockwise to decrease the volume-to-be-infus ed. A "confirm" button 6 is arranged, when pressed, to cause the pump to deliver the selected volume of fluid (at the flow-rate set by digipot 1) when the aforementioned start button is operated. If the pump is already running, operating "confirm" button 6 causes the selected volume-to-be-infused setting to be changed to the new setting, as selected by digipot 4. Digipots 1 and 4 each have sixteen detented positions in three hundred and sixty degrees. The pump is required to be programmed to provide flow rates of between 0.5 and 999ml/hr and to deliver volumes of between 1 and 9999ml. Relying upon a normal change of one digipot position per unit change in flow rate or volume-to-be-infused, sweeping through the whole range in each case would be time consuming in the extreme. However, the microprocessor is programmed to be responsive to the rate at which pulses are generated by the digipots 1 or 4 such that upon fast rotation the setting of the respective operating parameter (flow rate or volume-to-be-infused, as the case may be) jumps from one predetermined preferred setting to the next (greater or lesser dependant upon the direction of rotation) in a series of preferred settings ("sticky numbers"). From that setting, the respective digipot is rotated again either quickly to jump to the next adjacent predetermined preferred setting or slowly to produce a change of setting unit by unit as the digipot in rotated from detented position to detented position. For setting the flow rate, the preferred rates between which the settings jump upon fast rotation of the digipot 1, in ml/hr are:- 0.5 5.0 25 41 50 81 100 125 and thereafter in multiples of 100ml/hr up to the aforementioned 999ml/hr. For setting the flow rate, all of the preferred settings have the same priority For setting the volume-to-be-infused however, it is more likely that multiples of 1000ml will be selected as the volume required rather than some intermediate value. Taking this into account, in the case of the volume-to-be-infused digipot 4 the microprocessor is programmed to be responsive to a third speed band as follows:- Slow rotation One increment/decrement per digipot detent position. Fast rotation Jump to next adjacent larger/smaller multiple of 100ml for one (or more) digipot detent position. Very fast rotation (flicking) Change to next adjacent larger/smaller multiple of 1000ml. Provided that the number of volume-to-be-infused digipot detent positions traversed does not exceed the number of positions that would be required to be traversed under slow rotation to change from one preferred setting to the next, on fast or very fast (flicking) rotation the number of detent positions traversed is irrelevant. Referring to Figure 2 and 3, whilst the programming of the microprocessor will be a matter within the competance of one skilled in the art having regard to the information hereinbefore given, the flow chart of Figure 2 appertaining to flow rate setting and the flow chart of Figure 3 appertaining to volume-to-be-infused (Vol t.b.i.) setting may be of assistance in this. For the sake of clarity, the legends used in the different blocks are repeated below. Figure 2 7. "1ms interrupt" 8. "16ms after last change?" 9. "Turbo counter = 0" 10. "Work out direction" 11. "Same sense as last time?" 12. "Turbo counter = 0" 13. "Sense?" 14. "Turbo counter = 0?" 15. "Turbo counter = 3?" 16. "Flow rate = 0.5?" 17. "Flow rate = last sticky number in list" 18. "Decrement flow rate by 1ml/hr" 19. "Display new flow rate" 20. "Increment turbo counter" 21. "Turbo counter = 0?" 22. "Turbo counter = 3?" 23. "Flow rate = 999.0?" 24. "Flow rate = next sticky number in list" 25. "Increment flow rate by 1ml/hr" 26. "Display new flow rate"*£12) 27. "Increment turbo counter" 28. "End". Figure 3 29. "1ms interrupt" 30. "16ms after last change?" 31. "Turbo counter = 0" 32. "Work out direction" 33. "Same sense as last time?" 34 "Turbo counter = 0" 35. "Sense" 36. "Turbo counter = 0?" 37. "Turbo counter = 3?" 38. "Turbo counter = 6?" 39. "Vol. t.b.i. = 0000?" 40. "Vol. t.b.i. = last factor of 100" 41. "Vol. t.b.i. = last factor of 1000" 42. "Display new flow rate" 43. "Increment turbo counter" 44. "Turbo counter = 0?" 45. "Turbo counter = 3?" 46. "Turbo counter = 6" 47. "Vol t.b.i. = 9999ml?" 48. "Vol t.b.i. = next factor of 100" 49. "Vol t.b.i. = next factor of 1000" 50. "Increment vol t.b.i. by 1ml" 51. "Display new Vol t.b.i." 52. "Increment turbo counter" 53. "End".

Claims: An electronically controlled intravenous infusion apparatus comprising setting means for setting the volume to be infused and the flow rate parameters of the apparatus in response to a respective signal generated by dedicated control devices (1,4) for each parameter, operatively connected with the setting means, each control device (1,4) comprising a movable control member and sensing means operable to sense the extent and speed that the control member is moved by an operator, each signal being indicative of the extent and speed of movement of said control member, the sensing means being operable to sense two or more rates of movement of the control member, including slow movement causing incremental change in the setting of the parameter, or respective parameter, and faster movement causing the setting of said parameter to jump from one predetermined preferred setting to another separated therefrom by a plurality of incremental setting changes. Apparatus as claimed in Claim 1 and such that for setting the flow rate said sensing means is operable to sense slow movement and fast movement. Apparatus as claimed in Claim 1 or Claim 2 and such that for setting the volume-to-be-infused said sensing means is operable to sense three rates of movement. Apparatus as claimed in Claim 3 and such that the sensing means is operable to sense slow movement of the control member of the control device for setting the volume to be infused causing incremental setting changes; fast movement causing the setting to jump to the next multiple of 100ml of volume of fluid to be infused and very fast movement causing the setting to jump to the next adjacent multiple of 1000ml of volume-to-be-infused. Apparatus as claimed in any of the above claims and wherein said movement is rotary movement. Apparatus as claimed in any preceding claim wherein each said control device (1,4) is a digipot or shaft encoder.

Inventors: DANBY HAL, DANBY, HAL
Applicants: BAXTER INT, BAXTER INTERNATIONAL INC.
Application year: 1992
Main classification: G05B19
IPC codes: G05B19, A61M5