Drawing drug from a vial

1. An apparatus for delivering a therapeutic substance to a subject, the apparatus comprising:

a therapeutic substance delivery device:

(a) configured to engage with a therapeutic substance reservoir, and

(b) comprising a pump configured to draw the therapeutic substance from the reservoir into a pump chamber disposed within the therapeutic substance delivery device without changing internal dimensions of the reservoir, a volume of the therapeutic substance within the pump chamber varying in response to changes in internal dimensions of the pump chamber;

an orientation sensor coupled to the therapeutic substance delivery device and configured to generate an output indicative of an orientation of the therapeutic substance delivery device with respect to gravity; and

control circuitry configured to drive the pump to:

(a) calculate a volume of the therapeutic substance disposed within the reservoir,

(b) drive the pump to draw the therapeutic substance into the pump chamber in response to (i) the calculated volume of the therapeutic substance disposed within the reservoir, in combination with (ii) an output from the orientation sensor that the therapeutic substance delivery device is in an orientation that allows the therapeutic substance to be drawn from the reservoir, and

(c) drive the pump to deliver the therapeutic substance from the pump chamber to the subject.

2. The apparatus according to claim 1 , wherein the therapeutic substance reservoir is a prefilled reservoir.

3. The apparatus according to claim 1 , wherein the therapeutic substance reservoir is configured to be filled by the subject prior to engagement of the therapeutic substance reservoir with the therapeutic substance delivery device.

4. The apparatus according to claim 1 , wherein the orientation sensor comprises an accelerometer.

5. The apparatus according to claim 1 , wherein the control circuitry is configured to drive the pump to draw the therapeutic substance into the pump chamber substantially not in response to a predetermined therapeutic substance delivery schedule.

6. The apparatus according to claim 1 , wherein the control circuitry is configured to drive the pump to interrupt the delivering of the therapeutic substance from the pump chamber to the subject by driving the pump to draw the therapeutic substance into the pump chamber from the therapeutic substance reservoir.

7. The apparatus according to claim 1 , wherein the control circuitry is configured to drive the pump to draw the therapeutic substance into the pump chamber regardless of whether there is therapeutic substance within the pump chamber.

8. The apparatus according to claim 1 , wherein:

(A) the pump comprises:

a fluid intake path, wherein the pump is configured to draw the therapeutic substance from the reservoir into the pump chamber via the fluid intake path,

a fluid exit path, wherein the pump is configured to deliver the therapeutic substance from the pump chamber to the subject via the fluid exit path, and

an air detector positioned to detect air within the fluid exit path, and

(B) the control circuitry is configured to, in response to air being drawn into the pump chamber via the fluid intake path, calculate an amount of air detected within the fluid exit path.

9. The apparatus according to claim 8 , wherein the control circuitry is configured to continue to drive the pump to deliver the therapeutic substance from the pump chamber to the subject in response to less than a threshold amount of air being detected in the fluid exit path.

10. The apparatus according to claim 8 , wherein the control circuitry is configured such that, in response to more than a threshold amount of air being detected in the fluid exit path, the control circuitry performs a compensatory calculation to correct the calculated volume of therapeutic substance in the reservoir.

11. The apparatus according to claim 8 , wherein the control circuitry is configured such that, in response to the amount of air detected in the fluid exit path passing an air-limit threshold, the control circuitry pauses the pump until an output from the orientation sensor is received that the therapeutic substance delivery device is in an orientation that allows the therapeutic substance to be drawn from the reservoir.

12. A method for delivering a therapeutic substance to a subject, the method comprising:

using a therapeutic substance delivery device:

drawing the therapeutic substance from a therapeutic substance reservoir into a pump chamber of the therapeutic delivery device, and

delivering the therapeutic substance from the pump chamber to the subject,

the drawing of the therapeutic substance being:

(i) without changing internal dimensions of the reservoir, and

(ii) substantially in response to (a) a volume of therapeutic substance in the reservoir, in combination with (b) an orientation of the therapeutic substance delivery device.

13. The method according to claim 12 , wherein the drawing of the therapeutic substance is substantially not in response to a predetermined therapeutic substance delivery schedule.

14. The method according to claim 12 , wherein drawing the therapeutic substance from the therapeutic substance reservoir comprises interrupting the delivering of the therapeutic substance from the pump chamber by filling the pump chamber with therapeutic substance from the therapeutic substance reservoir.

15. The method according to claim 12 , wherein drawing the therapeutic substance from the reservoir comprises drawing the therapeutic substance from the reservoir regardless of whether there is therapeutic substance within the pump chamber.

16. The method according to claim 12 , further comprising, using an orientation sensor, sensing the orientation of the therapeutic substance delivery device and generating an output indicative of the orientation of the therapeutic substance delivery device, and wherein drawing the therapeutic substance from the therapeutic substance reservoir into the pump chamber comprises drawing the therapeutic substance from the therapeutic substance reservoir substantially in response to (a) the volume of therapeutic substance in the reservoir, in combination with (b) the output from the orientation sensor.

17. The method according to claim 12 , wherein:

drawing the therapeutic substance comprises drawing the therapeutic substance from the therapeutic substance reservoir into the pump chamber via a fluid intake path,

delivering the therapeutic substance from the pump chamber to the subject comprises delivering the therapeutic substance from the pump chamber via a fluid exit path, and

the method further comprises, using an air detector, detecting that air has been drawn into the pump chamber by detecting air within the fluid exit path.

18. The method according to claim 17 , further comprising:

using control circuitry, calculating an amount of air detected within the fluid exit path, and

in response to less than a threshold amount of air being detected in the fluid exit path, continuing to deliver the therapeutic substance from the pump chamber to the subject.

19. The method according to claim 18 , wherein, using the control circuitry, in response to more than the threshold amount of air being detected in the fluid path, performing a compensatory calculation to correct the calculated volume of therapeutic substance in the reservoir.

20. The method according to claim 17 , further comprising:

using control circuitry, determining an amount of air detected within the fluid exit path, and

in response to the amount of air detected in the fluid exit path passing an air-limit threshold, pausing the drawing until the orientation of the therapeutic substance delivery device is an orientation that allows the therapeutic substance to be drawn from the reservoir.