Gravity-independent infusion system
First Claim
1. An infusion system comprising a source of liquid infusate contained in an infusate bag and pressurized by means external to said bag to a substantially constant known driving pressure , of at least 200 Torr, said pressure driving a flow rate of said liquid infusate through a cutoff valve in series with a flow restrictor of selectable, substantially constant, known hydraulic resistance, said flow restrictor consisting of at least one small-bore flow passage having a length and a diameter, the ratio of said length to said diameter being at least 10, and said length being at least 3 millimeters, and said restrictor providing substantially all of the resistance to flow of said liquid infusate when said cutoff valve is open and said infusate is flowing, whereby said flow rate is then substantially constant.
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Accused Products
Abstract
An infusion system utilizing a pressurized source of infusate comprises a capillary tube flow restrictor having sufficient length and suitably large ratio of length to internal diameter to provide reliably repeatable fluid resistance and minimum damage to infusate. The internal diameter of the flow restrictor may be made to decrease with increasing temperature so that the flow rate of the infusate is substantially independent of temperature. The flow restrictor may include means for indicating pressures and flow of infusate.
133 Citations
19 Claims
- 1. An infusion system comprising a source of liquid infusate contained in an infusate bag and pressurized by means external to said bag to a substantially constant known driving pressure , of at least 200 Torr, said pressure driving a flow rate of said liquid infusate through a cutoff valve in series with a flow restrictor of selectable, substantially constant, known hydraulic resistance, said flow restrictor consisting of at least one small-bore flow passage having a length and a diameter, the ratio of said length to said diameter being at least 10, and said length being at least 3 millimeters, and said restrictor providing substantially all of the resistance to flow of said liquid infusate when said cutoff valve is open and said infusate is flowing, whereby said flow rate is then substantially constant.
- 8. A flow restrictor, for use in an infusion system comprising a source of liquid infusate pressurized to a substantially constant known driving pressure, from 200 up to about 500 Torr, said pressure driving a flow rate of said liquid infusate through said restrictor, said restrictor consisting of at least one small-bore flow passage having a length and a diameter, the ratio of said length to said diameter being at least 10, and said length being at least 3 millimeters, said restrictor having hydraulic resistance adequate to provide a pressure differential of flowing liquid infusate of the order of 200 to 500 Torr, and said restrictor further comprising connection means for connecting said restrictor into said infusion system, said connection means being adequate to withstand driving pressure up to at least 500 Torr.
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17. A flow restrictor, for use in an infusion system comprising a source of liquid infusate pressurized to a substantially constant known driving pressure driving a flow rate of liquid infusate through said restrictor, comprising a smallbore flow passage, defined within a length of capillary tubing and having a length and a diameter, the ratio of said length to said diameter being at least 10, and said length being at least 3 millimeters, said flow restrictor being further capable of indicating pressure and flow of said liquid infusate and further comprising:
- a tubular duct sealably surrounding said capillary tubing and extending upstream and downstream thereof;
holes in the wall of said duct at locations just upstream and downstream of said capillary tubing;
thin-wall elastomeric tubing surrounding said duct and sealed thereto at distances upstream and downstream of said holes to provide sealed annuli inflatable by pressurized infusate flowing outward through said holes; and
a transparent cylindrical jacket surrounding said elastomeric tubing and radially spaced therefrom at a small distance such that said elastomeric tubing touches said jacket when said annuli are inflated. - View Dependent Claims (18, 19)
- a tubular duct sealably surrounding said capillary tubing and extending upstream and downstream thereof;
Specification