Energy-Based Ablation Completion Algorithm
An electrosurgical generator is disclosed. The generator includes sensor circuitry configured to measure voltage and current delivered to tissue and a controller configured to measure time of energy delivery to tissue and to calculate energy delivered to tissue, the controller further configured to estimate a size of an ablation volume as a function of energy delivered to tissue and time and to calculate a growth rate of the ablation volume based on the estimated size.
1 . An electrosurgical generator, comprising:
sensor circuitry configured to measure voltage and current delivered to tissue; and
a controller configured to measure time of energy delivery to tissue and to calculate energy delivered to tissue, the controller further configured to estimate a size of an ablation volume as a function of energy delivered to tissue and time and to calculate a growth rate of the ablation volume based on the estimated size.
2 . The electrosurgical generator according to claim 1 , wherein the controller is further configured to compare the calculated growth rate to a threshold growth rate.
3 . The electrosurgical generator according to claim 2 , wherein the controller is configured to perform an action in response to a comparison of the calculated growth rate to the threshold growth rate, the action selected from the group consisting of terminating supply of energy to tissue and issuing an alarm.
4 . The electrosurgical generator according to claim 1 , wherein the controller is configured to calculate the growth rate based on differentiation of a plurality of estimated sizes.
5 . The electrosurgical generator according to claim 1 , wherein the controller is configured to calculate the estimated size as an inverse of a sum of inverses of the measured time and the calculated energy.
6 . A method for ablating tissue, comprising:
measuring time of energy delivery to tissue;
calculating energy delivered to tissue based on measured voltage and current;
estimating a size of an ablation volume as a function of energy delivered to tissue and time; and
calculating a growth rate of the ablation volume based on the estimated size.
7 . The method according to claim 6 , further comprising comparing the calculated growth rate to a threshold growth rate.
8 . The method according to claim 7 , further comprising terminating a supply of energy to tissue in response to a comparison of the calculated growth rate to the threshold growth rate.
9 . The method according to claim 6 , further comprising calculating the growth rate based on differentiation of a plurality of estimated sizes.
10 . The method according to claim 6 , further comprising calculating the estimated size as an inverse of a sum of inverses of the measured time and the calculated energy.
11 . A method of ablating tissue, comprising:
applying at least one electrosurgical waveform to tissue in a pulsitile manner;
measuring reactive impedance of the tissue;
measuring time of energy delivery to tissue;
determining peaks of the reactive impedance corresponding to the pulses of the at least one electrosurgical waveform;
calculating a growth rate of the ablation volume based on the estimated size.
12 . The method according to claim 11 , further comprising comparing the calculated growth rate to a threshold growth rate.
13 . The method according to claim 12 , further comprising terminating supply of energy to tissue in response to a comparison of the calculated growth rate to the threshold growth rate.
14 . The method according to claim 11 , further comprising calculating the growth rate based on differentiation of a plurality of estimated sizes.
15 . The method according to claim 11 , further comprising calculating the estimated size as an inverse of a sum of inverses of the measured time and the calculated energy.