Bolus delivery device

1. A bolus delivery device comprising:

a housing;

a reservoir disposed within the housing for receipt of a volume of a fluid, the reservoir defined by an activation dome and a reservoir seat, the reservoir having a fluid pressure that varies as the volume of the fluid varies within the reservoir;

a piston axially disposed within the reservoir and extending through an orifice in the reservoir seat, the piston having a proximal end and a distal end;

a biasing member disposed around the distal end of the piston;

a seal member disposed around the distal end of the piston and against a distal side of the orifice in the reservoir seat;

an expandable bladder disposed in the housing, the expandable bladder in fluid communication with the reservoir for receipt of the fluid from the reservoir;

an actuator for initiating a flow of the fluid from the reservoir to the expandable bladder;

an inlet conduit in fluid communication with the reservoir for providing the fluid to the reservoir; and

an outlet conduit in fluid communication with the expandable bladder for providing the fluid to a patient,

wherein the biasing member has a biasing force that overcomes the fluid pressure of the reservoir when the reservoir is substantially empty to push the seal member against the distal side of the reservoir seat.

2. The bolus delivery device of claim 1 , wherein the reservoir seat is located between the activation dome and the expandable bladder such that the reservoir seat is distal to the activation dome and proximal to the expandable bladder.

3. The bolus delivery device of claim 1 , wherein the activation dome is connected to the actuator and the proximal end of the piston such that operating the actuator displaces the piston to displace the seal member and initiate the flow of fluid from the reservoir to the expandable bladder.

4. The bolus delivery device of claim 1 , wherein the seal member is free to slide along the piston.

5. The bolus delivery device of claim 1 , wherein the expandable bladder expands as the fluid is received and contracts as the fluid is dispensed.

6. The bolus delivery device of claim 1 , further comprising a collar disposed between the seal member and the biasing member.

7. The bolus delivery device of claim 1 , wherein the housing defines ribs that limit expansion of the expandable bladder.

8. The bolus delivery device of claim 1 , wherein the expandable bladder extends between a proximal connector and a distal connector, and wherein the inlet conduit is in fluid communication with the distal connector and the outlet conduit is in fluid communication with the distal connector.

9. The bolus delivery device of claim 1 , further comprising a stop that catches in a groove defined in the actuator to limit distal movement of the actuator.

10. The bolus delivery device of claim 8 , further comprising an internal conduit extending from the distal connector to the reservoir, the internal conduit providing fluid communication between the inlet conduit and the reservoir.

11. A bolus delivery device comprising:

a housing;

a reservoir disposed within the housing for receipt of a volume of a fluid, the reservoir defined by an activation dome and a reservoir seat;

a piston axially disposed within the reservoir and extending through an orifice in the reservoir seat, the piston having a proximal end and a distal end;

a seal member disposed around the distal end of the piston and against a distal side of the orifice in the reservoir seat, wherein the seal member is free to slide along the piston;

a bladder disposed in the housing and in fluid communication with the reservoir for receipt of the fluid from the reservoir, wherein the bladder expands as the fluid is received and contracts as the fluid is dispensed; and

an actuator for initiating a flow of the fluid from the reservoir to the bladder.

12. The bolus delivery device of claim 11 , wherein the reservoir seat is located between the activation dome and the bladder such that the reservoir seat is distal to the activation dome and proximal to the bladder.

13. The bolus delivery device of claim 11 , further comprising a biasing member disposed around the distal end of the piston, wherein the activation dome is connected to the actuator and the proximal end of the piston such that operating the actuator displaces the piston to displace the seal member and initiate the flow of fluid from the reservoir to the bladder.

14. The bolus delivery device of claim 11 , wherein the housing defines ribs that limit expansion of the bladder.

15. The bolus delivery device of claim 11 , further comprising:

an inlet conduit in fluid communication with the reservoir for providing the fluid to the reservoir; and

an outlet conduit in fluid communication with the bladder for providing the fluid to a patient.

16. The bolus delivery device of claim 13 , wherein the reservoir has a fluid pressure that varies as the volume of the fluid varies within the reservoir, and wherein the biasing member has a biasing force that overcomes the fluid pressure of the reservoir when the reservoir is substantially empty to push the seal member against the distal side of the reservoir seat.

17. The bolus delivery device of claim 13 , further comprising a collar disposed between the seal member and the biasing member.

18. The bolus delivery device of claim 15 , wherein the bladder extends between a proximal connector and a distal connector, and wherein the inlet conduit is in fluid communication with the distal connector and the outlet conduit is in fluid communication with the distal connector.

19. The bolus delivery device of claim 18 , further comprising an internal conduit extending from the distal connector to the reservoir, the internal conduit providing fluid communication between the inlet conduit and the reservoir.

20. An infusion assembly comprising:

an elastomeric pump configured to provide a fluid under pressure;

a continuous flow path in fluid communication with the pump for providing a continuous and substantially constant flow rate of fluid from the pump;

a bolus flow path for delivery of a bolus dose of the fluid; and

a bolus delivery device in fluid communication with the bolus flow path and configured to receive fluid from the pump, the bolus delivery device including:

a housing;

a reservoir disposed within the housing for receipt of a volume of a fluid, the reservoir defined by an activation dome and a reservoir seat, the reservoir having a fluid pressure that varies as the volume of the fluid varies within the reservoir;

a piston axially disposed within the reservoir and extending through an orifice in the reservoir seat, the piston having a proximal end and a distal end;

a biasing member disposed around the distal end of the piston;

a seal member disposed around the distal end of the piston and against a distal side of the orifice in the reservoir seat;

an expandable bladder disposed in the housing, the expandable bladder in fluid communication with the reservoir for receipt of the fluid from the reservoir;

an actuator for initiating a flow of the fluid from the reservoir to the expandable bladder;

an inlet conduit in fluid communication with the reservoir for providing the fluid to the reservoir; and

an outlet conduit in fluid communication with the expandable bladder for providing the fluid to a patient,

wherein the biasing member has a biasing force that overcomes the fluid pressure of the reservoir when the reservoir is substantially empty to push the seal member against the distal side of the reservoir seat.