IP Library › Granted Patent US 12,521,162
Granted Patent B2
US 12,521,162 · App. 18/116,889 · Granted Jan 13, 2026

Systems and methods for calculating tissue impedance in electrosurgery

Inventors: Donald W. Heckel (Thornton, CO); Andrey Belous (Longmont, CO)
Assignee: Covidien LP
A61B18/1233A61B18/1206A61B18/1445G05B15/02G06F17/10A61B2018/00577A61B2018/00589A61B2018/00601A61B2018/0063A61B2018/00642A61B2018/00648A61B2018/00702A61B2018/00755A61B2018/00767A61B2018/00779A61B2018/00827A61B2018/00875A61B2018/00892
View Patent ↗
Loading inventors, assignments & file history…
Monitor This Case
Get email alerts when status or documents change.
Order Certified Copies
Most orders are placed with the USPTO same day — all within 24 business hours.
Order via The Patent Place →
Pre-filled with this patent's details
Quick Facts
Patent No.
US 12,521,162
App. No.
18/116,889
Granted
Jan 13, 2026
Kind
B2
Abstract

An electrosurgical generator and associated methods determine a real part of the impedance of treated tissue. The electrosurgical generator includes an output stage, a plurality of sensors, and a controller that controls the output stage. The controller includes a signal processor that determines an RMS voltage, an RMS current, an average power, and a real part of the impedance of the treated tissue based on measured voltage and current by using a plurality of averaging filters. The controller controls the output stage to generate electrosurgical energy based on at least the determined real part of the impedance.

Claims (38)

1 . A system, comprising:

one or more processors; and

one or more processor-readable media storing instructions which, when executed by the one or more processors, cause performance of:

generating, via a plurality of moving average filters, a Root Mean Square (RMS) voltage based on a voltage waveform of electrosurgical energy being delivered to tissue;

generating, via the plurality of moving average filters, an average power based on a current waveform of the electrosurgical energy and the voltage waveform;

generating, via the plurality of moving average filters, an RMS current based on the current waveform;

determining, based on the average power and the RMS current, a real part of an impedance of the tissue; and

controlling delivery of the electrosurgical energy to the tissue based on at least one of the RMS voltage, the average power, the RMS current, or the real part of the impedance.

2 . The system according to claim 1 , wherein the one or more processor-readable media further store instructions which, when executed by the one or more processors, cause performance of determining the real part of the impedance by dividing the average power by the RMS current.

3 . The system according to claim 1 , wherein the one or more processor-readable media further store instructions which, when executed by the one or more processors, cause performance of sampling the voltage waveform and the current waveform to obtain a predetermined number of samples of each of the voltage waveform and the current waveform.

4 . The system according to claim 3 , wherein the predetermined number of samples corresponds to an integer multiple of an RF frequency of the voltage waveform and the current waveform.

5 . The system according to claim 1 , wherein the one or more processor-readable media further store instructions which, when executed by the one or more processors, cause performance of multiplying the voltage waveform and the current waveform to obtain a power waveform, wherein the average power is generated via the plurality of moving average filters based on the power waveform.

6 . The system according to claim 1 , wherein the one or more processor-readable media further store instructions which, when executed by the one or more processors, cause performance of calculating phase information between the voltage waveform and the current waveform by dividing the average power by a product of the RMS voltage and the RMS current.

7 . The system according to claim 1 , wherein the plurality of moving average filters includes three identical low pass filters.

8 . The system according to claim 7 , wherein the one or more processor-readable media further store instructions which, when executed by the one or more processors, cause performance of synchronously operating the three identical low pass filters over a predetermined number of pulses.

9 . The system according to claim 1 , wherein the plurality of moving average filters includes a cascaded integrator comb filter.

10 . The system according to claim 1 , wherein the plurality of moving average filters includes a boxcar averaging filter.

11 . The system according to claim 1 , wherein the plurality of moving average filters includes a finite impulse response filter.

12 . The system according to claim 1 , wherein the plurality of moving average filters includes an infinite impulse response filter.

13 . A system, comprising:

one or more processors; and

one or more processor-readable media storing instructions which, when executed by the one or more processors, cause performance of:

generating, via a plurality of moving average filters, an average power based on at least a current waveform of electrosurgical energy being delivered to tissue;

generating, via the plurality of moving average filters, a Root Mean Square (RMS) current based on the current waveform;

determining, based on the average power and the RMS current, a real part of an impedance of the tissue; and

controlling delivering of the electrosurgical energy to the tissue based on at least one of the average power, the RMS current, or the real part of the impedance.

14 . The system according to claim 13 , wherein the one or more processor-readable media further store instructions which, when executed by the one or more processors, cause performance of generating, via the plurality of moving average filters, an RMS voltage based on a voltage waveform of the electrosurgical energy.

15 . The system according to claim 13 , wherein the one or more processor-readable media further store instructions which, when executed by the one or more processors, cause performance of determining the real part of the impedance by dividing the average power by the RMS current.

16 . The system according to claim 13 , wherein the one or more processor-readable media further store instructions which, when executed by the one or more processors, cause performance of sampling the current waveform to obtain a predetermined number of samples of the current waveform.

17 . The system according to claim 16 , wherein the predetermined number of samples corresponds to an integer multiple of an RF frequency of the current waveform.

18 . The system according to claim 13 , wherein the plurality of moving average filters includes three identical low pass filters.

19 . The system according to claim 18 , wherein the one or more processor-readable media further store instructions which, when executed by the one or more processors, cause performance of synchronously operating the three identical low pass filters over a predetermined number of pulses.

20 . One or more non-transitory processor readable media storing instructions which, when executed by one or more processors, cause performance of:

generating, via a first moving average filter, a Root Mean Square (RMS) voltage based on a voltage waveform of electrosurgical energy being delivered to tissue;

generating, via a second moving average filter, an average power based on a current waveform of the electrosurgical energy and the voltage waveform;

generating, via a third moving average filter, an RMS current based on the current waveform;

determining, based on the average power and the RMS current, a real part of an impedance of the tissue; and

controlling delivery of the electrosurgical energy to the tissue based on at least one of the RMS voltage, the average power, the RMS current, or the real part of the impedance of the tissue.

Assignments (1)
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Mar 3, 2023
From: HECKEL, DONALD W.; BELOUS, ANDREY
To: COVIDIEN LP
Reel/Frame 062867/0380 →
Continuity (4)
Division 16696193 · Nov 26, 2019
Division 14562907 · Dec 8, 2014
Provisional Application 61975070 · Apr 4, 2014
Related Publication 20230200881A1 · Jun 29, 2023
References Cited (167)
US 4186437A · Cuk · 1980 [cited by applicant]
US 4727874A · Bowers et al. · 1988 [cited by applicant]
US 5632272A · Diab et al. · 1997 [cited by applicant]
US 5722975A · Edwards et al. · 1998 [cited by applicant]
US 6843789B2 · Goble · 2005 [cited by applicant]
US 6948503B2 · Refior et al. · 2005 [cited by applicant]
US D574323S · Waaler · 2008 [cited by applicant]
US 7844017B2 · Wiss · 2010 [cited by applicant]
US 7972329B2 · Refior et al. · 2011 [cited by applicant]
US 8114021B2 · Robertson et al. · 2012 [cited by applicant]
US 8308721B2 · Shibata et al. · 2012 [cited by applicant]
US 8568411B2 · Falkenstein et al. · 2013 [cited by applicant]
US 8579894B2 · Falkenstein et al. · 2013 [cited by applicant]
US 8685015B2 · Gilbert · 2014 [cited by applicant]
US 8915910B2 · Falkenstein et al. · 2014 [cited by applicant]
US 9270202B2 · Johnson et al. · 2016 [cited by applicant]
US 9283028B2 · Johnson · 2016 [cited by applicant]
US 9498275B2 · Wham et al. · 2016 [cited by applicant]
US 9498276B2 · Gilbert · 2016 [cited by applicant]
US 9504516B2 · Mattmiller et al. · 2016 [cited by applicant]
US 9519021B2 · Gilbert · 2016 [cited by applicant]
US 9522032B2 · Behnke · 2016 [cited by applicant]
US 9559594B2 · Johnson et al. · 2017 [cited by applicant]
US 9636165B2 · Larson et al. · 2017 [cited by applicant]
US 9642670B2 · Johnson et al. · 2017 [cited by applicant]
US 9655670B2 · Larson et al. · 2017 [cited by applicant]
US 9705456B2 · Gilbert · 2017 [cited by applicant]
US 9770283B2 · Gilbert et al. · 2017 [cited by applicant]
US 9770287B2 · Kerr · 2017 [cited by applicant]
US 9839469B2 · Gilbert et al. · 2017 [cited by applicant]
US 9867651B2 · Wham · 2018 [cited by applicant]
US 9872719B2 · Johnson · 2018 [cited by applicant]
US 9895186B2 · Gilbert · 2018 [cited by applicant]
US 10058374B2 · Wham · 2018 [cited by applicant]
US 10130412B2 · Wham · 2018 [cited by applicant]
US 10285750B2 · Coulson et al. · 2019 [cited by applicant]
US 10492850B2 · Heckel · 2019 [cited by examiner]
US 11607264B2 · Heckel et al. · 2023 [cited by applicant]
US 20040167508A1 · Wham et al. · 2004 [cited by applicant]
US 20120078139A1 · Aldridge et al. · 2012 [cited by applicant]
US 20140276754A1 · Gilbert et al. · 2014 [cited by applicant]
US 20150025521A1 · Friedrichs et al. · 2015 [cited by applicant]
US 20150025523A1 · Friedrichs et al. · 2015 [cited by applicant]
US 20150316587A1 · Dionne et al. · 2015 [cited by applicant]
DE 179607C · 1906 [cited by applicant]
DE 390937C · 1924 [cited by applicant]
DE 1099658B · 1961 [cited by applicant]
DE 1139927B · 1962 [cited by applicant]
DE 1149832B · 1963 [cited by applicant]
DE 1439302A1 · 1969 [cited by applicant]
DE 2439587A1 · 1975 [cited by applicant]
DE 2455174A1 · 1975 [cited by applicant]
DE 2407559A1 · 1975 [cited by applicant]
DE 2602517A1 · 1976 [cited by applicant]
DE 2504280A1 · 1976 [cited by applicant]
DE 2540968A1 · 1977 [cited by applicant]
DE 2820908A1 · 1978 [cited by applicant]
DE 2803275A1 · 1979 [cited by applicant]
DE 2823291A1 · 1979 [cited by applicant]
DE 2946728A1 · 1981 [cited by applicant]
DE 3143421A1 · 1982 [cited by applicant]
DE 3045996A1 · 1982 [cited by applicant]
DE 3120102A1 · 1982 [cited by applicant]
DE 3510586A1 · 1986 [cited by applicant]
DE 3604823A1 · 1987 [cited by applicant]
DE 3904558A1 · 1990 [cited by applicant]
DE 3942998A1 · 1991 [cited by applicant]
DE 4206433A1 · 1993 [cited by applicant]
DE 4339049A1 · 1995 [cited by applicant]
DE 19506363A1 · 1996 [cited by applicant]
DE 19717411A1 · 1998 [cited by applicant]
DE 19848540A1 · 2000 [cited by applicant]
DE 102008058737A1 · 2010 [cited by applicant]
EP 0246350A1 · 1987 [cited by applicant]
EP 0267403A2 · 1988 [cited by applicant]
EP 0296777A2 · 1988 [cited by applicant]
EP 0310431A2 · 1989 [cited by applicant]
EP 0325456A2 · 1989 [cited by applicant]
EP 0336742A2 · 1989 [cited by applicant]
EP 0390937A1 · 1990 [cited by applicant]
EP 0556705A1 · 1993 [cited by applicant]
EP 0608609A2 · 1994 [cited by applicant]
EP 0836868A2 · 1998 [cited by applicant]
EP 0862060A2 · 1998 [cited by applicant]
EP 0880220A2 · 1998 [cited by applicant]
EP 0882955A1 · 1998 [cited by applicant]
EP 1051948A2 · 2000 [cited by applicant]
EP 1366724A1 · 2003 [cited by applicant]
EP 1776929A1 · 2007 [cited by applicant]
EP 2680016A2 · 2014 [cited by applicant]
EP 2898847A1 · 2015 [cited by applicant]
FR 1275415A · 1961 [cited by applicant]
FR 1347865A · 1964 [cited by applicant]
FR 2313708A1 · 1976 [cited by applicant]
FR 2364461A1 · 1978 [cited by applicant]
FR 2502935A1 · 1982 [cited by applicant]
FR 2517953A1 · 1983 [cited by applicant]
FR 2573301A1 · 1986 [cited by applicant]
JP 63005876 · 1988 [cited by applicant]
JP 2002065690A · 2002 [cited by applicant]
JP 2005185657A · 2005 [cited by applicant]
SU 166452 · 1964 [cited by applicant]
SU 727201A2 · 1980 [cited by applicant]
WO 9308756A1 · 1993 [cited by applicant]
WO 9639088A1 · 1996 [cited by applicant]
WO 0211634A1 · 2002 [cited by applicant]
WO 0245589A2 · 2002 [cited by applicant]
WO 03090635A1 · 2003 [cited by applicant]
WO 2006050888A1 · 2006 [cited by applicant]
WO 2008053532A1 · 2008 [cited by applicant]
WO 2012110996A2 · 2012 [cited by applicant]
Wald et al., “Accidental Burns”, JAMA, Aug. 16, 1971, vol. 217, No. 7, pp. 916-921. [cited by applicant]
Vallfors et al., “Automatically Controlled Bipolar Electrosoagulation-‘COA-COMP’”, Neurosurgical Review 7:2-3 (1984) pp. 187-190. [cited by applicant]
Sugita et al., “Bipolar Coagulator with Automatic Thermocontrol”, J. Neurosurg., vol. 41, Dec. 1944, pp. 777-779. [cited by applicant]
Prutchi et al. “Design and Development of Medical Electronic Instrumentation”, John Wiley & Sons, Inc. 2005. [cited by applicant]
Momozaki et al. “Electrical Breakdown Experiments with Application to Alkali Metal Thermal-to-Electric Converters”, Energy conversion and Management; Elsevier Science Publishers, Oxford, GB; vol. 44, No. 6, Apr. 1, 2003… [cited by applicant]
Muller et al. “Extended Left Hemicolectomy Using the LigaSure Vessel Sealing System”, Innovations That Work; Company Newsletter; Sep. 1999. [cited by applicant]
“Electrosurgical Unit Analyzer ESU-2400 Series User Manual” Apr. 1, 2002; Retrieved from Internet: < URL:http://www.bcgroupintl.com/ESU_2400/Updates/ESU-2400_UM_Rev04.pdf>, pp. 6, 11, 73. [cited by applicant]
Ogden Goertzel Alternative to the Fourier Transform: Jun. 1993 pp. 485-487, Electronics World; Reed Business Publishing, Sutton, Surrey, BG vol. 99, No. 9. 1687. [cited by applicant]
Hadley I C D et al., “Inexpensive Digital Thermometer for Measurements on Semiconductors”, International Journal of Electronics; Taylor and Francis. Ltd.; London, GB; vol. 70, No. 6 Jun. 1, 1991; pp. 1155-1162. [cited by applicant]
Burdette et al. “In Vivo Probe Measurement Technique for Determining Dielectric Properties at VHF Through Microwave Frequencies”, IEEE Transactions on Microwave Theory and Techniques, vol. MTT-28, No. 4, Apr. 1980 pp. 4… [cited by applicant]
Richard Wolf Medical Instruments Corp. Brochure, “Kleppinger Bipolar Forceps & Bipolar Generator”, 3 pp. Jan. 1989. [cited by applicant]
Astrahan, “A Localized Current Field Hyperthermia System for Use with 192-Iridium Interstitial Implants” Medical Physics, 9 (3), May/Jun. 1982. [cited by applicant]
Alexander et al., “Magnetic Resonance Image-Directed Stereotactic Neurosurgery: Use of Image Fusion with Computerized Tomography to Enhance Spatial Accuracy”, Journal Neurosurgery, 83; (1995) pp. 271-276. [cited by applicant]
Geddes et al., “The Measurement of Physiologic Events by Electrical Impedence” Am. J. Mi, Jan. Mar. 1964, pp. 16-27. [cited by applicant]
Cosman et al., “Methods of Making Nervous System Lesions”, In William RH, Rengachary SS (eds): Neurosurgery, New York: McGraw-Hill, vol. 111, (1984), pp. 2490-2499. [cited by applicant]
Anderson et al., “A Numerical Study of Rapid Heating for High Temperature Radio Frequency Hyperthermia” International Journal of Bio-Medical Computing, 35 (1994) pp. 297-307. [cited by applicant]
Benaron et al., “Optical Time-Of-Flight and Absorbance Imaging of Biologic Media”, Science, American Association for the Advancement of Science, Washington, DC, vol. 259, Mar. 5, 1993, pp. 1463-1466. [cited by applicant]
Cosman et al., “Radiofrequency Lesion Generation and Its Effect on Tissue Impedance”, Applied Neurophysiology 51: (1988) pp. 230-242. [cited by applicant]
Zlatanovic M., “Sensors in Diffusion Plasma Processing” Microelectronics 1995; Proceedings 1995; 20th International Conference CE on Nis, Serbia Sep. 12-14, 1995; New York, NY vol. 2 pp. 565-570. [cited by applicant]
Ni W. et al. “A Signal Processing Method for the Coriolis Mass Flowmeter Based on a Normalized . . . ”, Journal of Applied Sciences—Yingyong Kexue Xuebao, Shangha CN, vol. 23 No. 2;(Mar. 2005); pp. 160-164. [cited by applicant]
Chicharo et al. “A Sliding Goertzel Algorith” Aug. 1996, pp. 283-297, Signal Processing, Elsevier Science Publishers B.V. Amsterdam, NL vol. 52 No. 3. [cited by applicant]
Bergdahl et al., “Studies on Coagulation and the Development of an Automatic Computerized Bipolar Coagulator” Journal of Neurosurgery 75:1, (Jul. 1991) pp. 148-151. [cited by applicant]
Cosman et al., “Theoretical Aspects of Radiofrequency Lesions in the Dorsal Root Entry Zone”, Neurosurgery 15: (1984) pp. 945-950. [cited by applicant]
Goldberg et al., “Tissue Ablation with Radiofrequency: Effect of Probe Size, Gauge, Duration, and Temperature on Lesion Volume” Acad Radio (1995) vol. 2, No. 5, pp. 399-404. [cited by applicant]
Medtrex Brochure—Total Control at Full Speed, “The O.R. Pro 300”, 1 p. Sep. 1998. [cited by applicant]
Valleylab Brochure “Valleylab Electroshield Monitoring System”, 2 pp. Nov. 1995. [cited by applicant]
U.S. Appl. No. 10/406,690 dated Apr. 3, 2003 inventor: Behnke. [cited by applicant]
U.S. Appl. No. 10/573,713 dated Mar. 28, 2006 inventor: Wham. [cited by applicant]
U.S. Appl. No. 11/242,458 dated Oct. 3, 2005 inventor: Becker. [cited by applicant]
European Search Report issued in application No. EP14200059, dated Aug. 24, 2015. [cited by applicant]
European Office Action dated Apr. 12, 2018 and issued in corresponding European Patent Application No. 14200059.5, 7 pages. [cited by applicant]
U.S. Appl. No. 10/761,524 dated Jan. 21, 2004 inventor: Wham. [cited by applicant]
U.S. Appl. No. 14/096,341 dated Dec. 4, 2013 inventor: Johnson. [cited by applicant]
U.S. Appl. No. 14/098,859 dated Dec. 6, 2013 inventor: Johnson. [cited by applicant]
U.S. Appl. No. 14/100,113 dated Dec. 9, 2013 inventor. Gilbert. [cited by applicant]
U.S. Appl. No. 14/147,294 dated Jan. 3, 2014 inventor: Gilbert. [cited by applicant]
U.S. Appl. No. 14/147,312 dated Jan. 3, 2014 inventor: Gilbert. [cited by applicant]
U.S. Appl. No. 14/168,296 dated Jan. 30, 2014, inventor: Mattmiller. [cited by applicant]
U.S. Appl. No. 14/174,551 dated Feb. 6, 2014 inventor: Johnson. [cited by applicant]
U.S. Appl. No. 14/174,607 dated Feb. 6, 2014 inventor: Friedrichs. [cited by applicant]
U.S. Appl. No. 14/179,724 dated Feb. 13, 2014 inventor: Johnson. [cited by applicant]
U.S. Appl. No. 14/180,965 dated Feb. 14, 2014 inventor: Larson. [cited by applicant]
U.S. Appl. No. 14/181,114 dated Feb. 14, 2014 inventor: Larson. [cited by applicant]
U.S. Appl. No. 14/182,797 dated Feb. 18, 2014 inventor: Wham. [cited by applicant]
U.S. Appl. No. 14/190,830 dated Feb. 26, 2014 inventor: Johnson. [cited by applicant]
U.S. Appl. No. 14/190,895 dated Feb. 26, 2014 inventor: Gilbert. [cited by applicant]
U.S. Appl. No. 14/255,051 dated Apr. 17, 2014 inventor: Coulson. [cited by applicant]
U.S. Appl. No. 14/262,219 dated Apr. 25, 2014, inventor: Gilbert. [cited by applicant]
U.S. Appl. No. 14/267,066 dated May 1, 2014, inventor: Friedrichs. [cited by applicant]
U.S. Appl. No. 14/268,187 dated May 2, 2014, inventor: Kerr. [cited by applicant]
U.S. Appl. No. 14/283,604 dated May 21, 2014, inventor: Behnke. [cited by applicant]
U.S. Appl. No. 14/297,771 dated Jun. 6, 2014, inventor: Wham. [cited by applicant]
U.S. Appl. No. 14/297,812 dated Jun. 6, 2014, inventor: Wham. [cited by applicant]
U.S. Appl. No. 14/297,890 dated Jun. 6, 2014, inventor: Wham. [cited by applicant]
U.S. Appl. No. 14/320,762 dated Jul. 1, 2014, inventor: Gilbert. [cited by applicant]
U.S. Appl. No. 14/320,804 dated Jul. 1, 2014, inventor: Gilbert. [cited by applicant]