Energy delivery system for vessel sealing

An electrosurgical energy delivery system for sealing interior passageways of vessels of a patient, the system comprising:

• a generator capable of delivering electrosurgical power by producing an output voltage and an output current;
• a surgical tool electrically connected to the generator for receiving the electrosurgical power, the surgical tool having electrically conductive members arranged for grasping the vessels of the patient and for transmitting the electrosurgical power thereto, the surgical tool having means for maintaining a closure force between the members sufficient to substantially close the interior passageways, and
• a power control circuit in the generator for automatically sequencing the electrosurgical power delivered to the surgical tool while the output voltage is kept below one-hundred-sixty volts RMS, wherein the sequence includes raising the output current to a maximum amplitude greater than about two amperes RMS while the surgical tool is applying the closure force, thereafter lowering the electrosurgical power to desiccate the vessels without charring, and thereafter terminating the electrosurgical power to the surgical tool;
• wherein the generator includes means for substantially terminating the power delivery to the surgical tool when the output current leads the output voltage by an angle greater than approximately fifty degrees.

A method for sealing interior passageways of vessels of a patient using electrosurgical power, the electrosurgical power having an output voltage and an output current which are applied through end effectors of a surgical tool, the method comprising the steps of:

• applying compression to the vessels of the patient with the end effectors sufficient to substantially close the interior passageways;
• applying a first level of electrosurgical power to the vessels, wherein the output current has a maximum RMS amplitude greater than two amperes and the output voltage is less than one hundred sixty volts RMS;
• reducing the electrosurgical power to a second level which is less than half of the first level;
• applying the second level of electrosurgical power to the vessels and other tissue of the patient for a length of time sufficient to cause desiccation without charring;
• reducing the electrosurgical power substantially to zero for a length of time sufficient to allow the vessels to cool into a new compressed form;
• and
• relieving the compression on the vessels.

A method for sealing interior passageways of vessels of a patient using electrosurgical power, the electrosurgical power having an output voltage and an output current which are applied through end effectors of a surgical tool, the method comprising the steps of:

• applying compression to the vessels of the patient with the end effectors sufficient to substantially close the interior passageways;
• approximating impedance of the vessels;
• increasing the electrosurgical power to the vessels until the output current has a maximum of greater than two amperes while the output voltage is held below one hundred sixty volts RMS;
• decreasing the electrosurgical power delivery to the vessels until the impedance rises above approximately one thousand ohms;
• reducing the electrosurgical power substantially to zero for a duration of less than five seconds;
• and
• relieving the compression on the vessels.

A method for sealing interior passageways of vessels larger than 2.5 millimeters in diameter of a patient using electrosurgical power, the vessels comprised of proteins, the electrosurgical power having an output voltage and an output current which are applied through end effectors of a surgical tool, the method comprising the steps of:

• applying compression to the vessels of the patient with the end effectors sufficient to substantially close the interior passageways;
• increasing the electrosurgical power to the vessels until the output current has a maximum value which is sufficient to melt the proteins;
• decreasing the electrosurgical power delivery to the vessels so that the vessels becomes desiccated without being charred;
• reducing the electrosurgical power substantially to zero for a duration sufficient to cool the vessels into a new compressed form;
• and
• relieving the compression on the vessels.