In recent years laser technology has gained wide-spread use in almost all fields, including surgery. The laser is "intensified light," and a laser beam can cut or coagulate. Both laser and electrosurgery work on a similar biological principle -- the cellular fluid is intensively heated causing the cell membrane to explode (as in cutting), or to slowly dehydrate (the process of coagulation).

Laser surgery was introduced in the early 1950s, but it did not gain popularity until the last 10 years. Electrosurgery, in use since the turn of this century, uses high frequency (radio-frequency) energy for cutting and various forms of coagulation.

There are many different kinds of lasers. In this review we refer to the CO2 laser, not the other modalities such as YAG, etc.

BIOLOGICAL ACTIONS OF LASER AND ELECTROSURGERY

In electrosurgery, the high density of the RF current applied by the active electrosurgical electrode causes a cutting action, provided the electrode has a small surface (needle, lancet, scalpel). Depending on (1) the shape of the electrode, (2) the frequency and wave modulation, (3) peak-to-peak voltage, (4) current and output impedance of the generator, the cut can be smooth, with absolutely no arcing, or it can be charring and burn the tissue. This great variation of tissue effects is frequently ignored or misunderstood, which is why some surgeons claim that the cut with an electrosurgical scalpel provides better wound healing than a laser, while others claim the reverse. Electrosurgical coagulation may be carried out in many different forms -- from slow, delicate contact coagulation with bipolar forceps, to light charring and burning in the spray coagulation mode. The biological effect, accordingly, significantly differs from gentle tissue dehydration to burning, charring and even carbonization. The temperature differences during. the various coagulation processes may vary between 100 degrees Celsius to well over 500 degrees Celsius.

Reviewing these many variables, and looking at video tapes produced by prominent surgeons, one can see why claims are being made in favor of laser surgery.

The laser beam has a cutting effect similar to electrosurgery, without tissue contact but, since there are fewer variables with the laser, the cut is more uniform. This may be an advantage for some surgeons, but a disadvantage for other surgeons, depending on many factors.

Coagulation with the laser is similar to spray coagulation, but perhaps more controllable and predictable. Again, this depends on the instrumentation and experience with the different modalities.

CUTTING WITH LASER AND ELECTROSURGERY

The electrosurgical cutting electrode can be a fine micro-needle, a lancet, a knife, a wire or band loop, a snare, or even an energized scalpel or scissors. This indicates the enormous variations, and the requirement to choose the proper device -- because the electrode also determines the cutting performance.

Additionally. the current waveform is a significant factor in the cutting performance. A smooth, non-modulated current is more suitable for scalpel-like cutting, whereas the modulated current gives cuts with predetermined coagulation.

The output intensity selected, as well as the output impedance of the generator, are also important with respect to cutting performance. Having so many parameters and choices, there is no wonder that some surgeons are unhappy with the cutting performance of their electrosurgical system; some believe that selecting the right electrode alone guarantees the desired results. If all the parameters mentioned are taken into consideration, with understanding, the electrosurgical cut will be precisely the way the most discriminating surgeon desires.

Cutting with the laser looks to be simpler with respect to the number of parameters to be considered; the surgeon needs only to target the beam, have it in focus, and select the proper intensity. However, tissue excavation or snaring is simply not possible with the laser.

TARGETING THE SURGICAL AREA

The targeting of the surgical area is obviously more simple with the electrosurgical method because, even under the microscope, the active electrode is first aligned to the intended approach, and then the generator is activated. With forceps coagulation, unipolar or bipolar, the targeting is not only more simple, but the forceps are also used to mechanically close the vessel. This is something the laser cannot do.

The targeting of the laser beam is much more critical, and generally requires an expensive optical system. Once the laser is activated, the beam better be on target; no mechanical tissue manipulation with the active electrode is possible.

SNARING POLYPS AND TONSILS

The removal of nasal polyps, tonsils and polyps in the colon has become an established method of treatment by electrosurgical current. While the snare wire strangles the polyp, the electrosurgical current cuts and coagulates simultaneously. Without the electrosurgical modality, endoscopic polypectomy would not be possible.

The laser is not suitable for this surgical procedure.

TRANSURETHRAL RESECTION (TUR)

Endoscopic surgery within the urinary bladder became possible after the electrosurgical modality was introduced. While cryo has also been used in this discipline, it has not established itself as a practical method. The YAG laser is now being introduced for certain coagulating processes in the bladder, with promising results. However, TUR remains an electrosurgical operation.

EXCAVATION OF TISSUE

The active electrosurgical electrode can be shaped into any form suiting the anatomical requirements. The tissue removal, particularly in tumor surgery with wire and band loop electrodes, is a practical and preventative method over tissue removal with the cold steel.

The laser beam is not suitable for tissue excavation.

OPEN-AIR COAGULATION WITH LASER AND ELECTROSURGERY

For this surgical procedure, both modalities are perhaps equally suitable, and some favor the laser as a more predictable modality. On the other hand if the surgeon chooses the proper waveform, intensity, and electrode, he can produce predictable and delicate results. Dermatologists and gynecologists have demonstrated electrosurgery to be free from complications. If important parameters are not carefully adhered to, neither electrosurgery nor laser modality will be free from difficulties.

It is generally claimed that the laser beam is superior in pinpoint coagulations. Under the microscope, however, one can demonstrate that the micro-electrosurgical process may be equal and perhaps simpler to apply if a microsurgical unit and electrodes are used.

COAGULATING WITH UNIPOLAR AND BIPOLAR FORCEPS

With proper use, electrosurgery procedures have become simpler, reducing operating time and blood loss, especially when the electro-hemostat or forceps are used. With bipolar forceps and the appropriate generator, the descriminating, delicate microsurgical procedures can be performed.

The surgical laser has no possibilities for this important surgical involvement.

SUCTION COAGULATION

Many surgical procedures from MICRO to MACRO surgery in ENT, neurosurgery, laparoscopjc and microsurgical procedures use suction cannulae and a combination of suction and coagulation. The high-frequency current-carrying suction cannulae will coagulate the bleeding tissue at the same time the body liquid is removed. From the simple nose bleed to the neurosurgical operation or the laparoscopic approach, suction coagulation in the unipolar mode (and, more recently, bipolar has become a standard procedure in outpatient and major surgery. Laser and suction seem not to be practical and, thus, they are not combined.

SAFETY FOR PATIENT AND SURGEON

Both electrosurgical and laser modalities are safe if the equipment is kept in perfect working condition and all technical requirements are fulfilled. Surgical accidents with both electrosurgery and laser have been reported. Most were caused by lack of attention and respect for proper requirements and procedures.

THE SMOKE PROBLEM

Both electrosurgery and laser surgery are known to produce undesirable smoke, compared with cold steel surgery. The smoke derives from the burning of the tissue, becoming a major problem in endoscopic surgery. With electrosurgery, the amount of smoke produced may be significant or insignificant; in bipolar applications or cutting with non-modulated current, there is little smoke, if any.

With laser surgery, there is always a great amount of smoke because of the extremely high temperatures which cause the cell to burn up. In electrosurgery, the same way be true when spray coagulation, or heavy blending cutting, is performed. However, in delicate procedures, such as microsurgical cutting and bipolar coagulation, the surgical process is performed at low temperatures and, thus, tissue dehydration rather than tissue burning occurs.

Particularly in laparoscopic interventions, insufflators with an increased flow rate and smoke exhaustion are necessary when laser applications are performed. These are not necessary during electrosurgical procedures.

COST EFFECTIVENESS

A rule of thumb states that each output watt from a laser costs about $1,000, compared with $10 for electrosurgical equipment. This means that an average laser costs between $20,000 to $50,000 compared with an electrosurgical unit cost of between $1,000 and $5,000.

Operating expenditures--maintenance and repair costs--are in a similar relationship. Electrosurgical units are relatively reliable and, in event of a breakdown, the repair rarely exceeds 20% of the purchase price.

CONCLUSION

"The laser: still a bridesmaid, not yet a bride" says Drs. Brodman and Reyniak in the respective titled article published in 1984 issue of Contemporary OB/GYN. The laser receives an enormous publicity as a "Star Wars" technology. Yet the laser will have to show more features, applications and reliability before it will excel in the armamentarium of surgical technology and procedures. The laser will find its place but, at this time, there is excessive enthusiasm and nonobjectivity displayed by many laser promoters. Critical surgeons want objectivity. This review provides an objective comparison between electrosurgery and laser surgery.

THE AUTHOR

KARL HAUSNER has been President of Elmed Incorporated since 1969. Prior to this, he was Division Manager of Siemens Medical of America, Incorporated. He holds degrees in natural science and engineering, and has over 25 years experience in biomedical technology. He may be contacted at Elmed, 60 West Fay Ave., Addison, IL 60101, 630/543-2792.