Method of controlling a surgical system based on irrigation flow

• US 20050209621A1
• Filed: 02/28/2005
• Published: 09/22/2005
• Est. Priority Date: 03/22/2004
• Status: Active Grant

• Current Assignee: Alcon Incorporated
• Original Assignee: Alcon Incorporated
• Inventors: Gordon, Raphael, Yadlowsky, Ann, Boukhny, Mikhail, Morgan, Michael D.
• Granted Patent: US 7,645,255 B2
• Time in Patent Office: Days
• US Class Current: 606/169
• CPC Class Codes: A61B 2017/00973 pedal-operated
• CPC Class Codes: A61F 9/00745 using mechanical vibrations, e.g. ultrasonic
• CPC Class Codes: A61M 1/77 Suction-irrigation systems aspiration tips supplying fluids A61M1/85; specific for negative pressure wound therapy A61M1/92; combined with tracheal tubes A61M16/0463
• CPC Class Codes: A61M 2205/3368 Temperature
• CPC Class Codes: A61M 2205/50 with microprocessors or computers
• CPC Class Codes: A61M 3/0202 with electronic control means or interfaces
• CPC Class Codes: A61M 3/0216 Pressure
• CPC Class Codes: A61M 3/022 Volume; Flow rate
• CPC Class Codes: A61M 3/0258 by means of electric pumps

Abstract

A surgical system that is able to sense the onset of an occlusion or other surgical event as well as the instant an occlusion breaks. To help avoid overheating of the tip, the system determines a temperature of an eye using irrigation flow rate and reduces the power to the handpiece automatically if an overheating situation is predicted. Alternatively or in addition, the system monitors the power drawn by the handpiece, which is indicative of the cutting load on the tip, and automatically adjusts the power or stroke of the tip to compensate for increased loads on the tip.

Claims

1. A method of controlling a surgical system, the surgical system having an ultrasound handpiece, the ultrasound handpiece having a cutting tip, the method comprising the steps of:

establishing a threshold temperature;

monitoring an irrigation pressure in a line running to the ultrasound handpiece;

calculating a rate of flow of the irrigation fluid;

determining a heat absorption capacity for the calculated rate of flow of irrigation fluid;

determining a temperature of an eye based on the determined heat absorption capacity and an amount of power being supplied to the ultrasound handpiece;

comparing the determined temperature of the eye to the threshold temperature; and

if necessary, adjusting the amount of power delivered to the cutting tip of the ultrasound handpiece based on the comparison of the determined and threshold temperatures.

2. The method of claim 1, adjusting the amount of power comprising adjusting a duty cycle of the output of the ultrasound handpiece.

3. The method of claim 1, adjusting power comprising adjusting a stroke or amplitude of the output of the ultrasound handpiece.

4. The method of claim 1, adjusting power comprising reducing power if the determined temperature exceeds the threshold temperature.

5. The method of claim 1, wherein the power is maintained or increased if the determined temperature is below the threshold temperature.

16. The method of claim 1, further comprising determining a rate of change of aspiration vacuum of the ultrasound handpiece.

17. The method of claim 16, wherein determining the stage of occlusion is based on the rate of change of the irrigation pressure and aspiration vacuum.

6. A method of controlling a surgical system, the surgical system having an ultrasound handpiece, the ultrasound handpiece having a cutting tip, the method comprising the steps of:

establishing a threshold temperature;

monitoring an irrigation pressure in a line running to the ultrasound handpiece;

calculating a rate of flow of the irrigation fluid;

determining a heat absorption capacity for the calculated rate of flow of irrigation fluid;

determining a temperature of an eye based on the determined heat absorption capacity and an amount of power being supplied to the ultrasound handpiece;

comparing the determined temperature of the eye to the threshold temperature; and

determining a rate of change of the irrigation pressure;

determining a stage of occlusion based on the rate of change of the irrigation fluid; and

if necessary, adjusting an amount of power delivered to the cutting tip of the ultrasound handpiece based on the determined stage of occlusion and based on the comparison of the determined and threshold temperatures.

7. The method of claim 6, adjusting the amount of power comprising adjusting a duty cycle of the output of the ultrasound handpiece.

8. The method of claim 6, adjusting power comprising adjusting a stroke or amplitude of the output of the ultrasound handpiece.

9. The method of claim 6, adjusting power comprising reducing power if the determined temperature exceeds the threshold temperature.

10. The method of claim 6, wherein the power is maintained or increased if the determined temperature is below the threshold temperature.

11. The method of claim 6, further comprising detecting a pattern of data of the irrigation pressure.

12. The method of claim 11, detecting the pattern comprising determining a linear correlation between a predefined pattern and data of the irrigation pressure during operation of the surgical system.

13. The method of claim 12, determining the linear correlation comprising performing a linear transformation.

14. The method of claim 11, detecting the pattern comprising calculating a derivative of data of the first operating parameter over time.

15. The method of claim 11, detecting the pattern comprising performing a convolution of a predefined pattern and data of the first operating parameter during operation of the surgical system.

18. The method of claim 6, determining the stage of occlusion comprising identifying an onset or preliminary indication of occlusion.

19. The method of claim 18, the onset being identified by an increasing aspiration vacuum.

20. The method of claim 19, further comprising determining a rate of change of aspiration vacuum, the onset being identified by increasing irrigation pressure and aspiration vacuum.

21. The method of claim 20, the irrigation pressure increasing at a faster rate than the aspiration vacuum.

22. The method of claim 6, determining the stage of occlusion comprising identifying a pre-occlusion condition.

23. The method of claim 22, the pre-occlusion condition being identified by an a substantially constant irrigation pressure

24. The method of claim 19, further comprising determining a rate of change of an aspiration vacuum, the pre-occlusion condition being identified by a substantially constant irrigation pressure and an increasing aspiration vacuum.

25. The method of claim 24, the aspiration vacuum during the pre-occlusion condition increasing at a slower rate than during a period of time between an onset of occlusion and the pre-occlusion condition.

26. The method of claim 6, determining the stage of occlusion comprising identifying a full occlusion.

27. The method of claim 26, further comprising determining a rate of change of an aspiration vacuum, the full occlusion being identified by substantially constant irrigation pressure and aspiration vacuum.

28. The method of claim 6, determining the stage of occlusion comprising identifying a break of an occlusion.

29. The method of claim 28, the first operating parameter comprising an irrigation pressure, the break being identified by a decreasing irrigation pressure.

30. The method of claim 29, further comprising determining a rate of change of an aspiration vacuum, the break of an occlusion being identified by decreasing irrigation pressure and aspiration vacuum.

31. The method of claim 6, determining the stage of occlusion comprising identifying a recovery from a break of an occlusion.

32. The method of claim 31, the recovery being identified by a slowing of a rate of decrease of the irrigation pressure.

33. The method of claim 32, further comprising determining a rate of change of an aspiration vacuum, the recovery being identified by a slowing of a rate of decrease of the irrigation pressure and a slowing of a rate of decrease of the aspiration vacuum.

34. The method of claim 6, determining the stage of occlusion comprising determining identifying

an onset of an occlusion,

a pre-occlusion condition following the onset,

a full occlusion following the pre-occlusion condition,

a break of the full occlusion;

or

a recovery following the break.

35. A method of controlling a surgical system, the surgical system having an ultrasound handpiece, the ultrasound handpiece having a cutting tip, the method comprising the steps of:

establishing a threshold temperature;

monitoring an irrigation pressure in a line running to ultrasound handpiece;

calculating a rate of flow of the irrigation fluid;

determining a heat absorption capacity for the calculated rate of flow of irrigation fluid;

determining a temperature of an eye based on the determined heat absorption capacity and an amount of power being supplied to the ultrasound handpiece;

comparing the determined temperature of the eye to the threshold temperature; and

determining a rate of change of the irrigation pressure;

determining a stage of occlusion based on the rate of change of the irrigation fluid; and

if necessary, adjusting an amount of power delivered to the cutting tip of the ultrasound handpiece based on the determined stage of occlusion and based on the comparison of the determined and threshold temperatures.,

the power delivered to the handpiece being reduced if the determined temperature exceeds the threshold temperature, the power delivered to the handpiece being maintained or increased if the determined temperature is below the threshold temperature.

36. The method of claim 35, adjusting the amount of power comprising adjusting a duty cycle of the output of the ultrasound handpiece.

37. The method of claim 35, adjusting power comprising adjusting a stroke or amplitude of the output of the ultrasound handpiece.

38. The method of claim 35, further comprising detecting a pattern of data of the irrigation pressure.

39. The method of claim 38, detecting the pattern comprising determining a linear correlation between a predefined pattern and data of the irrigation pressure during operation of the surgical system.

40. The method of claim 39, determining the linear correlation comprising performing a linear transformation.

41. The method of claim 38, detecting the pattern comprising calculating a derivative of data of the irrigation pressure over time.

42. The method of claim 35, detecting the pattern comprising performing a convolution of a predefined pattern and data of the irrigation pressure during operation of the surgical system.

43. The method of claim 35, further comprising determining a rate of change of an aspiration vacuum.

44. The method of claim 43, wherein determining the stage of occlusion is based on the rate of change of the irrigation pressure and aspiration vacuum.

45. The method of claim 35, determining the stage of occlusion comprising identifying an onset or preliminary indication of occlusion.

46. The method of claim 45, the onset being identified by an increasing aspiration vacuum.

47. The method of claim 35, determining the stage of occlusion comprising identifying a pre-occlusion condition.

48. The method of claim 47, the pre-occlusion condition being identified by a substantially constant irrigation pressure

49. The method of claim 48, further comprising determining a rate of change of an aspiration vacuum, the pre-occlusion condition being identified by a substantially constant irrigation pressure and an increasing aspiration vacuum.

50. The method of claim 49, the vacuum pressure during the pre-occlusion condition increasing at a slower rate than during a period of time between an onset of occlusion and the pre-occlusion condition.

51. The method of claim 35, determining the stage of occlusion comprising identifying a full occlusion.

52. The method of claim 51, further comprising determining a rate of change of an aspiration vacuum, the full occlusion being identified by substantially constant irrigation pressure and aspiration vacuum.

53. The method of claim 35, determining the stage of occlusion comprising identifying a break of an occlusion.

54. The method of claim 53, the first operating parameter comprising an irrigation pressure, the break being identified by a decreasing irrigation pressure.

55. The method of claim 54, further comprising determining a rate of change of an aspiration vacuum, the break of an occlusion being identified by decreasing irrigation pressure and aspiration vacuum.

56. The method of claim 35, determining the stage of occlusion comprising identifying a recovery from a break of an occlusion.

57. The method of claim 56, the recovery being identified by a slowing of a rate of decrease of the irrigation pressure.

58. The method of claim 57, further comprising determining a rate of change of an aspiration vacuum, the recovery being identified by a slowing of a rate of decrease of the irrigation pressure and a slowing of a rate of decrease of the aspiration vacuum.

59. The method of claim 35, determining the stage of occlusion comprising determining identifying

an onset of an occlusion,

a pre-occlusion condition following the onset,

a full occlusion following the pre-occlusion condition,

a break of the full occlusion;

or

a recovery following the break.