Monopolar probe

The monopolar probe (C.R. Youmans et af, 1970) has a small differential electrode inside a catheter, which may be routed to the site of bleeding through the endoscope. At the same time, the nondifferential electrode surface is fastened to one of the patient s extremities. Highly concentrated electrical energy is emitted from the probe and effects deep tissue coagulation. Primary haemostasis was achieved in 79 — 91% of the reported cases recurrent bleeding only occurred in 6-8%. (30)... 

The electrohydrothermoprobe (EHT) (W Matek et al., 1983) is a refinement of the monopolar probe. It allows a stream of water to be directed through the probe the site of bleeding can thus be irrigated and rendered more easily visible, and at the same time, charring of the tissue in contact with the probe is prevented. In 92% of reported cases, definitive haemostasis was achieved, with recurrent bleeding in 11% of patients. 

Analysis of the literature reveals no significant differences between electrocoagulation and (very expensive) laser treatment procedures in terms of primary or definitive haemostasis. With laser therapy, the complication rate (0—4%) lies above that of electrocoagulation (0%). Heat and bipolar probes may be regarded as the most tissue-friendly , an inference supported by the results of animal experiments, while laser and monopolar probe methods are more aggressive . The electrohydrothermal probe offers a compromise. An additional consideration is that electrocoagulation and EHT procedures are technically uncomplicated, locally applicable and lower in cost compared to laser methods. 

Due to the high number of tested probe molecule it was possible to apply both, the van Oss concept using monopolar probe molecules and the Gutman approach using bipolar probes, ys and ys numbers as well as Ka and Kb are summarised in Table 3 together with the dispersive surface energies. 

After the determination of the dispersive work of adhesion from the Hexane experiment the total work of adhesion can be determined for Dichloromethane. This probe molecule represents a monopolar acid according to the van Oss concept and can be therefore used to determine the base number (ys ) of the surface. For the corresponding determination of the acid number the measurement with a monopolar basic probe molecule is required. Typical candidates for this would be either Toluene or Ethyl acetate. These measurements haven t been completed yet. For this reason the ys -values in the result table are missing. 

Fig. 2M The electrochemical pump oelL (a) A monopolar cell for production of metal powdery. (After, Jansaon, R, E. W, and Ashworth, O A., (1977) J, Appt. EUctr0chem.j 7, 309). (b) Bipolar rotor celt for dectrosynthe jj. (After Jansson, R. E. W. Marshall, R. h and Rizzo, J. E. (1978) J, Appl Ekctrochem. 8i. 281). (c) An improved version of (b) which incorporates facilities for adjustment of the rotor position, a reference electrode probe and enhanced mass transport. The bipolar rotor has a diameter of 10 cm and rotates at 2800 rev min ...

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