Ambulatory infusion devices and methods

1. A method of monitoring an infusion device having an infusion device outlet and a fluid transfer device with a cycle that consists of a fluid transfer device operation and a rest period, the method comprising the steps of:

sensing pressure within a catheter connected to the infusion device outlet at the beginning of a single fluid transfer device cycle and prior to the operation of the fluid transfer device;

sensing pressure within the catheter at the end of the rest period of the single fluid transfer device cycle; and

determining that the catheter is blocked in response to the pressure sensed at the end of the rest period of the single fluid transfer device cycle being greater than the pressure sensed at the beginning of the single fluid transfer device cycle and prior to the operation of the fluid transfer device.

2. A method as claimed in claim 1 , wherein

the fluid transfer device comprises a piston pump; and

the fluid transfer device operation comprises a pump stroke.

3. A method as claimed in claim 1 , further comprising the step of:

taking high resolution samples of the pressure sensed during the single fluid transfer device cycle.

4. A method as claimed in claim 1 , wherein

the catheter includes a catheter outlet; and

sensing pressure within a catheter comprises sensing pressure at a location between the fluid transfer device and the catheter outlet.

5. A method as claimed in claim 1 , further comprising:

determining that the catheter is completely blocked in response to the pressure sensed at the end of the rest period of the single fluid transfer device cycle being substantially equal to the sum of the pressure sensed at the beginning of a single fluid transfer device cycle and prior to the operation of the fluid transfer device and a pressure increase associated with operation of the fluid transfer device.

6. A method as claimed in claim 1 , further comprising:

determining that the catheter is partially blocked in response to the pressure sensed at the end of the rest period of the single fluid transfer device cycle being less than the sum of the pressure sensed at the beginning of a single fluid transfer device cycle and prior to the operation of the fluid transfer device and a pressure increase associated with operation of the fluid transfer device.

7. A method as claimed in claim 1 , further comprising:

determining that the catheter is partially blocked in response to the catheter pressure sensed at the end of the rest period of the single fluid transfer device cycle being less than the sum of the catheter pressure sensed immediately prior to the beginning of the single fluid transfer device cycle and a pressure increase associated with operation of the fluid transfer device.

8. A method of monitoring an infusion device with a fluid transfer device that delivers fluid to a catheter, the method comprising the step of:

determining that there is a catheter blockage in response to a catheter pressure sensed at the end of a rest period of a single fluid transfer device cycle being greater than a catheter pressure sensed immediately prior to the beginning of the single fluid transfer device cycle.

9. A method as claimed in claim 8 , wherein

the fluid transfer device comprises a piston pump; and

the fluid transfer device operation comprises a pump stroke.

10. A method as claimed in claim 8 , wherein

the catheter includes a catheter outlet; and

the catheter pressure is sensed at a location between the fluid transfer device and the catheter outlet.

11. A method as claimed in claim 8 , further comprising:

determining that the catheter is completely blocked in response to the catheter pressure sensed at the end of the rest period of the single fluid transfer device cycle being substantially equal to the sum of the catheter pressure sensed immediately prior to the beginning of the single fluid transfer device cycle and a pressure increase associated with operation of the fluid transfer device.