CAUTERIES........power sources in surger
- 1. CAUTERIES PRESENTER: DR. MANOJ KUMAR MODERATOR:DR. INAMDAAR
- 2. O Cautery (Kauterion = hot iron) - destruction or denaturation of tissue by passive transfer of heat or application of caustic substance.
- 3. Electrosurgery and Cautery are not synonymous…. Electrosurgery (ESU) Cautery •Here, high frequency(RF) alternating current(AC) is used to raise the intracellular temperatures, so that vaporization (cutting) or the combination of desiccation and protein coagulation can be achieved. •The word cautery is derived from the greek word Kauterion, in which, destruction or denaturation of tissue is achieved by passively transferring heat from a heated instrument (resistant metal wire). •In this, since electric current is used to cut the tissues, force required is very less. •Cutting is done using conventional knife, because of which high force is required. •Wound healing time is lesser than cautery, and different effects can be used for performing cutting and/or coagulation. •DC/Low frequency AC is used to achieve the desired effect.
- 4. HISTORY OF CAUTERY O Ancient Egyptians (3000 BC) described the use of thermal cautery to treat diseases such as ulcers and tumors of the breast. O Hippocrates (469-370 BC) used heating to destroy a neck tumor. O Albucasis used a hot iron to control the bleeding process.
- 6. O In the year 1891, D’Arsonoval played a part in an important development in the field of electro-surgery. He discovered that, high frequency alternating current could be passed through the body without electric shocks. At a frequency greater than or equal to 20kHz, AC passing through the body does not produce muscle stimulation.
- 8. O When either AC or DC flows through a resistor, the resulting effect is the generation of heat, i.e., because there is resistance/impedance provided to the flow of current, thermal (heat) energy is generated.
- 9. The Men who developed the ESU….. Bovie and Cushing !!!! O William T. Bovie, a Physicist and Harvey W. Cushing, a neurosurgeon are often credited with the invention of the electrosurgical generator.
- 10. Fundamentals of Electrosurgery O RF- Electrosurgery can be classified into 2 types taking into consideration the return path these techniques follow.
- 11. O In the Monopolar type, the narrow active electrode concentrates the current (power) to the desired surgical site, and the large dispersive electrode (neutral electrode/patient plate), placed away from the surgical site. In the monopolar system, the entire patient is involved in the circuit.
- 12. O In the Bipolar type, both electrodes are mounted on the device (bipolar forceps) , located on or near the distal end, so that only the tissue grasped between the 2 poles gets affected. In this, only the tissue interposed between the electrodes is included in the circuit.
- 14. ELECTROSURGICAL UNIT O Converts a 60 cycles / sec (60 Hz), lowvoltage alternating current into higher voltage radio frequency (500 KHz - 3.0MHz) current.
- 15. Line frequency (50/60Hz) is converted into high frequency RF (300- 500kHz). Yellow represents cut (low voltage) and blue represents coagulation (high voltage)
- 16. Cut & Coag. waveforms O The Cutting waveform is a continuous sine wave signal, letting the surgeon do a pure cut on the tissue. O The Coagulation waveform on the other hand has a modulated, dampened, high voltage and a very low duty cycle signal.
- 17. O Duty cycle describes the percentage of time the ESU generator is producing a waveform or supplying current. If it is 80% of the time, it means 80% duty cycle.
- 20. Tissue effects of R.F.Electrical Current – O Vaporization or cutting. O Desiccation or coagulation.
- 25. Advantages – O - Easy to use. O - For tissue dissection. O - Greater tissue penetration. O - Area of Coaguation > BiPolar. Disadvantages – O - Larger volume of tissue injured. O - Can interfere with pacemakers. O - Requires distant return electrode.
- 27. CUTTING O In cutting or transection of the tissue, the cells start vaporizing, i.e. the liquid gets converted into steam. O This is achieved with a continuous, low- voltage waveform using a monopolar instrument with a narrow, pointed blade shaped electrode.
- 28. O The generator is activated, and because of the high power density (current concentration) at the tip, the tissue starts heating up faster, reaches ≥100 degree Celsius and separates/cuts the tissue. O Usually, the edge of the electrode is used in contact, since it can concentrate more current at a single location, and help in cutting purpose.
- 29. COAGULATION O In this process (coagulation & desiccation/dehydration), tissue temperatures reach anywhere between 60 & 95 degree Celsius. O When the tissue temperature is about 60 degree Celsius, the cellular fluid starts dehydrating (desiccation/dehydration), but the cellular structure is altered but not destroyed, as seen in vaporization (cutting).
- 30. O Usually, the flat end of the monopolar pencil is used for coagualation, as the area is more, because of which the current concentration at the site is less(distribution increases due to larger area of the electrode tip), and the heat delivery to the tissue would not be as high as the cutting mechanism.
- 31. What is a blended waveform or blend? O Originally, blended outputs were created by mixing/combining/blending waveforms from 2 physically different generators that produced the continuous low voltage and the modulated high voltage waveforms. O The modern ESU’s create blended outputs by producing modulated/interrupted versions of the pure cut waveforms.(Figures shown in the next slide).
- 33. BiPolar Cautery
- 34. 2 arms in hand piece. Damage to tissue between 2 electrodes. Decreased/no damage to surrounding tissue.
- 36. Advantages O Decreased Thermal injury to surrounding tissue. O Works well in saline. O In patients with Pacemaker. O Decreased Risk of capacitive coupling injuries. Aniso
- 37. Disadvantages O More skill. O Coagulation only. O No dissection capabilities.
- 38. TISSUE DAMAGE O50-80℃ = Tissue coagulation OAround 100℃ = Dessication & Vapourisation O200-300℃ = Tissue Carbonisation
- 39. O Amount of heat generation depends on - amount of tissue in contact with electrode (similar to pressure principle) O Short duration , High Voltage – Coagulation due to rapid tissue heating O Low Voltage , High wattage current – Tissue cutting
- 40. COMPLICATIONS O Burn injury. O Infections. O Active Electrode Trauma. O Current diversion. O Direct coupling. O Indirect coupling. O Capacitive coupling. O Dispersive electrode burns. O Smoke during electrocautery.
- 41. DIRECT AND INDIRECT COUPLING
- 45. ULTRASONIC DEVICES O Uses high frequency vibrations O Harmonic – for delivering precise energy for better vessel sealing capabilities upto 7mm vessels O Harmonic Scalpel – Vessel sealing & transecting capabilities O Work at 55KHz
- 47. ULTRASOUND DISSECTOR O Uses high-frequency mechanical vibrations to fragment tissue. O Used in ophthalmic, neuro, hepato-biliary and oncologic cytoreductive surgery. O Fragments tissue by contact with high water content cells. O Vibration generate vapor pockets within the cells that lead to disruption and fragmentation.
- 49. ULTRASONIC KNIFE O Produces vibrations at 55.5KHz at the tip of the blade via a hand piece transducer. O The moving blade couples with the tissue resulting in breakage of protein hydrogen bonds and thus protein coagulum forms.
- 50. O Can perform cutting and heamostasis with minimal damage. O Limited lateral spread and thermal injury. O No electrical energy transferred to patients.
- 52. ARGON BEAM COAGULATOR O Uses a spray of ionized argon gas as the active electrode rather than a metallic blade. O Allows even, efficient and broad application of the coagulating current to the tissues. O Ideal for obtaining haemostasis along the cut surface of the liver following hepatic resection.
- 54. LASER O Light Amplification by Stimulated Emission of Radiation. O Differs from regular light in the following properties, -Coherence (waves are synchronised or in phase with each other) -Monochromaticity (single wavelength) -Collimation (all light waves in parallel , so single beam)
- 56. O Lasers primarily being used for surgery, -Carbon Dioxide -Nd:YAG (Neodymium-doped Yittrium Aluminium Garnet) -Argon -Ho:YAG (Holmium-doped Yittrium Aluminium Garnet) -KTP (Potassium Titanyl Phosphate) -Excimer laser. -Helium neon laser. -Krypton laser. -Holmium laser.
- 57. Uses: O Cutaneous use. O Vascular use. O Laser in gastrointestinal diseases. O Uses in urology.
- 58. Advantages: O Precise with minimal damage to adjacent tissue. O Reduces postoperative pain. O Can be done under local anaesthesia. Disadvantages: O Misdirection of laser can occur. O Venous gas embolism. O Burns . O Cost .
- 59. LIGASURE O Ligasure – BiPolar Vessel Seal Device. -Combination of pressure & energy source to enable vessel seal.
- 60. Grips vessel tightly Measures resistance in tissue & sent to generator Delivers energy in pulsed manner Continues till vessel sealed Vessels upto 7mm with 3times normal systolic pressure
- 62. Hydrojet Device O Jet of water for dessection of tissue. O Liver parenchyma , Renal hilar dissection. O No thermal injury.