Disposable cassette with negative head height fluid supply

A fluid infusion pump comprising:

• (a) a disposable cassette having a relatively rigid first wall of said at least one pumping chamber and a movable second wall of said at least one pumping chamber defining an inlet passage, an outlet passage and at least one pumping chamber between said inlet passage and said outlet passage;
• (b) a pump body for receiving said disposable cassette in a fixed operating relationship;
• (c) an actuator mounted in said pump body and activatable for reciprocal advancement and retraction with respect thereto and adapted to confront said movable second wall when said disposable cassette is received in said pump body;
• and
• (d) a detachable coupling between said pump actuator and said movable second wall so that fluid is expelled from said at least one chamber on advancement of said actuator and so that fluid is positively drawn into said at least one chamber upon retraction of said actuator, said detachable coupling including a magnetically attractable disk attached to said movable second wall and a mechanism attached to said actuator for reciprocation therewith, which mechanism is magnetically attracted to said magnetically attractable disk attached to said movable wall.

A liquid infusion pump comprising:

• (a) a disposable cassette having an inlet passage and a transfer passage and forming at least one chamber between said inlet passage and said transfer passage, said at least one chamber having a movable wall with a magnetically attractable means attached to said movable wall;
• (b) a pump body for receiving said disposable cassette in a fixed operating relationship;
• (c) a magnetic actuator mounted in the pump body for reciprocation with respect thereto, and adapted to confront and to magnetically and detachably engage said magnetically attractable means attached to said movable wall when said disposable cassette is received in said pump body;
• (d) a pump drive for advancing and retracting said magnetic actuator, whereby fluid is expelled from said chamber on such advancement, and is drawn into the chamber as the actuator is retracted;
• (e) an inlet valve actuatable against said inlet passage and retractable therefrom;
• (f) a transfer valve actuatable against said transfer passage and retractable therefrom;
• (g) means for retracting said inlet valve from said inlet passage when said magnetic actuator is retracting and for actuating said inlet valve against said inlet passage when said magnetic actuator is advancing;
• and
• (h) means for actuating said transfer valve when said magnetic actuator is retracting and for retracting said transfer valve when said magnetic actuator is advancing so that fluid is drawn by negative pressure into said inlet chamber so that fluid is positively drawn in only from said inlet passage and fluid is expelled only from said transfer passage.

A pump for parenteral administration of fluid into a patient at a selectable rate comprising:

• (a) a disposable cassette having a relatively rigid carrier and a flexible sheet sealingly secured thereto defining a flow path between an inlet and an outlet, including an inlet passage, a supply chamber, a transfer passage, an outlet, a pump chamber and art outlet passage located along said flow path, said supply chamber positioned in said flow path of said disposable cassette between said inlet passage and said transfer passage leading to said outlet pump chamber and said supply chamber, including a magnetically attractable movable wall and a relatively rigid wall;
• (b) an instrument body having a compartment for receiving said disposable cassette;
• (c) an outlet pumping element associated with said instrument body adjacent to said compartment for receiving said disposable cassette and said confronting outlet pump chamber;
• (d) activation means for activating said outlet pumping element to reduce the volume of the outlet pump chamber at a rate dependent upon a selected rate;
• (e) a magnetic refill actuator carried by said instrument body for movement toward and away from said supply chamber and adapted to confront and detachably hold said magnetically attractable movable wall of said supply chamber;
• (f) an inlet valve actuatable to close or to open said inlet passage positioned between said inlet and said supply chamber of said disposable cassette
• (g) a transfer valve actuatable to close or open said transfer passage between the supply chamber and the outlet pumping chamber;
• (h) a delivery valve actuatable to close or open said outlet passage between said pump chamber and said outlet;
• and
• (i) control means for, at first times, closing the delivery inlet valves, opening the transfer valve, and retracting the pumping element from the outlet pump chamber while advancing the refill actuator towards the supply chamber, whereby the pump chamber is refilled, and at second times, opening the delivery valve and inlet valve and closing the transfer valve while advancing the outlet pumping element to reduce the volume or increase the pressure of the outlet pump chamber while retracting the refill actuator and supply chamber wall therewith for positively drawing fluid through said inlet passage into said supply chamber.

A disposable cassette for use in an infusion pumping instrument of the type having an inlet valve, an inlet pump actuator, a transfer valve, an outlet pump actuator, an outlet valve and means for replaceably holding a disposable cassette, said disposable cassette comprising:

• (a) a rigid carrier, having top and bottom surfaces and having a fluid path formed on said top surface, said fluid path including:
• (i) an inlet orifice;
• (ii) an outlet orifice;
• (iii) a concave inlet channel, communicating with said inlet orifice;
• (iv) a first concave pump indentation, communicating with said concave inlet channel;
• (v) a second concave pump indentation, having an access hole extending from said second pump indentation to said bottom surface of said rigid carrier;
• (vi) a concave transfer channel, communicating between said first and second concave pump indentations;
• and
• (vii) a concave outlet channel, communicating between said second concave indentation and said outlet orifice;
• (b) a flexible sheet, sealingly welded to said top surface along a perimeter edge of said fluid path immediately adjacent each of said orifices, concave channels and concave pump indentations, forming a continuous enclosed fluid passage between said flexible sheet and said rigid carrier, said fluid passage extending from said inlet orifice, along said inlet channel, through said first concave indentation, along said transfer channel, through said second concave indentation and along said outlet channel to said outlet orifice;
• and
• (c) a flexible membrane, welded in said second indentation sealing around said access hole, so that said fluid passage is entirely sealed except at said inlet and outlet orifices.