[Technological characteristics of endoscopic high frequency current and laser interventions]

High frequency current and laser radiation perform two possibilities to generate therapeutic and surgical heat. The integration of these two technologies into endoscopy resulted in important ancillary techniques in the hands of a surgeon. Starting from the principal methods for coagulation and dissection of tissue the respective technological aspects at the interaction of high frequency currents and intensive laser radiation with different wavelengths on biological tissue are illustrated. Mono- and bipolar HF-techniques as well as the light-guide assisted laser method in the contact and non-contact mode are explained. The special problems in endoscopy arising from the reduction in visibility by haemorrhages and the development of smoke at the thermally induced coagulation may be overcome successfully by the simultaneous instillation of a nearly isolating liquid during the HF-treatment. The so-called electrohydrothermosation (EHT) method is presented and several probes and instruments for endoscopic hemostasis and microsurgery are explained. For an increase in safety at the endoscopic application of HF-current the use of the bipolar technique is recommended and several technological developments used in this mode are pointed out. It is shown that the absorption of radiation through the water-content of the tissue is mainly responsible for the reactions which may be produced with laser-light. Furthermore it is mentioned that the range of lasers which might be used has a large spectrum of medical applications which had been even increased especially by the new erbium and holmium solid state lasers.(ABSTRACT TRUNCATED AT 250 WORDS)