The applications of technology for dissection in laparoscopy

Lasers

Lasers are rarely used in general laparoscopic surgery as they offer no advantages over more user friendly and safer forms of energized dissection & coagulation systems. The previous generation of lasers (with gas vapour chambers) was large, very expensive and required special power supply (3-phase electricity) and maintenance. In addition they lacked portability. The current generation of solid state diode-array lasers has overcome all these disadvantages and may well be used for certain applications of laparoscopic general surgery in the future. Currently laser ablation is used largely in gynaecological laparoscopic surgery, e.g. ablation of endometriosis and much less commonly for the photo-ablation of secondary tumours of the liver.

Ultrasonic system’s

Ultrasonic dissectors are of two types: low power which cleaves water containing tissues by cavitations leaving organized structures with low water content intact, e.g. blood vessels, bile ducts etc.; and high power systems which cleave loose areolar tissues by frictional heating and thus cut and coagulate the edges at the same time. Thus low power systems are used for liver surgery (Cusa, Selector) and do not coagulate vessels. High power systems (Autosonix, Ultracision) are used extensively especially in Fundoplication and laparoscopic colon surgery. It is important to remember that high power ultrasonic dissection systems may cause collateral damage by excessive heating and this is well documented in clinical practice.

Cryotherapy and Radio-frequency Ablation

Both are used in the laparoscopic ablation of secondary tumour deposits in the liver, usually when the lesions are inoperable for whatever reason, Laparoscopic cryotherapy with implantable probe destroys tumours by rapid freezing to -40°C or lower. The lesion re-vascularises for a short period (12— 14 hours) on thawing but because the vasculature and the tumour parenchyma are damaged beyond repair, hemorrhagic infraction ensues. With RF thermal ablation, a radiofrequency current is transmitted through the probe implanted in the tumour. The RF current causes molecular and ionic agitation which heats the tissues (much like the microwave) and hence the tumour is heated to destruction. Both modalities are operated with laparoscopic contact ultrasonographic scanning.

Haemostasis

Advanced procedures may require more extensive dissection and thus meticulous haemostasis becomes particularly important. Any loss of view will result in loss of control and hence decreased safety. Haemorrhage, even to a minor extent, tends to obscure their operative field and consequently is to be avoided. This means that vessels of a size that in open surgery could be divided without particular attention need to be secured prior to division when working endoscopically. Dissection must be more meticulous to proceed smoothly.

The magnification produced by the endoscope may initially confuse the surgeon as to the severity of bleeding. A moderate bleed can appear torrential. However an inexperienced endoscopic surgeon is well advised to convert should he have any doubt about his ability to control the situation expeditiously.