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Biomedical subjects

W Mautner

Publications and source records attributed to W Mautner.

At least 19 recordsLinked to original sources
PubMed1982

Comparison of argon laser photocoagulation and bipolar electrocoagulation for endoscopic hemostasis in the canine colon.

Severe bleeding from the lower gastrointestinal tract commonly occurs from mucosal lesions such as angiodysplasia and less often from acute ulcerations. Endoscopic coagulation of such lesions is now feasible. Our purpose was to compare the efficacy and histologic injury of bipolar electrocoagulation and argon laser photocoagulation applied at laparotomy in the canine colon. After right colotomy and heparinization in adult mongrel dogs, bleeding standard ulcers were randomly assigned to treatment or control. The colonic ulcers randomized to each group were not significantly different in size or bleeding rate. Efficacy of treatment was evaluated acutely. Adjacent normal mucosa was treated with the same modality as the ulcer to simulate treatment of a mucosal lesion. The same total exposure time (argon laser photocoagulation) or number of pulses (bipolar electrocoagulation) was used for these paired treatments. Gross and histologic injury were determined after 7 days. Both argon laser photocoagulation and bipolar electrocoagulation were uniformly effective in controlling bleeding from standard colonic ulcers and the incidence of full thickness injury was similar, 33%-48%. The histologic damage seen with normal mucosa treatment was consistently less than with standard ulcers for all treatment groups. The difference is easily explained by the reduction in colonic wall thickness of about 50% with creation of standard ulcers. In our opinion, argon laser photocoagulation and bipolar electrocoagulation are safe enough to be used in clinical trials for control of colonic bleeding from mucosal lesions but not acute colonic ulcers.

Animals↗
PubMed1982

Comparison of endoscopic electrocoagulation and laser photocoagulation of bleeding canine gastric ulcers.

The most promising endoscopic hemostatic techniques all depend upon heat to coagulate. Four thermally active techniques under similar controlled conditions in this endoscopic study were compared. The study was undertaken to compare the efficacy and histologic damage of monopolar electrocoagulation (MPEC), bipolar electrocoagulation (BPEC), argon laser photocoagulation (ALP) and neodymium-yytrium-aluminum-garnet (YAG) laser photocoagulation applied endoscopically to control bleeding from standard canine gastric ulcers. An open-closed model utilizing a nontraumatic intestinal clamp in heparinized adult mongrel dogs was used. Bleeding ulcers were randomly assigned to an endoscopic treatment modality or control. The endoscopic techniques and parameters of treatment for this study were established from a previous experience with each modality and from endoscopic treatment in pilot studies. Quantitative efficacy and subjective ease of endoscopic treatment were evaluated acutely; gross and histologic injury were determined after 7 days. Our conclusions were that more energy or greater power was required with each method to treat bleeding standard ulcers efficiently through the endoscope than at laparotomy. It was also concluded that each method was 93% or more effective in halting bleeding in this canine ulcer model but there were differences in ease of endoscopic use. Both lasers were much easier to apply than electrocoagulation. The order of decreasing ease of application was YAG, ALP, MPEC, BPEC. Argon laser and BPEC caused significantly less tissue injury than either MPEC or YAG. The order of increasing injury or decreasing margin of safety was ALP, BPEC, YAG and MPEC. In contrast to electrocoagulation, especially monopolar, laser related tissue injury was generally predictable and correlated with total treatment energy, animal weight or gastric overdistension, or both. The limitations, advantages, and disadvantages of each hemostatic technique are discussed and compared.

Animals↗
PubMed1980

YAG laser treatment of experimental bleeding canine gastric ulcers.

The neodymium-YAG laser was used to treat bleeding experimental canine gastric ulcers in four separate studies: (a) Extensive investigation by using the 1.06 micron YAG laser wavelength was performed to determine optimal YAG laser treatment parameters to maximize hemostatic efficacy while minimizing associated tissue injury. Eight out of 43 combinations of power, pulse duration, and spot size, with and without coaxial CO2 were found to be best. The range of settings tested were 30-90 W for power; 0.2-1 sec pulse duration; and 2.0- and 3.4-mm spot sizes, with and without coaxial CO2. (b) Five of these treatment combinations were studied in more detail to assess the respective effect of spot size, pulse duration, and presence or absence of coaxial CO2 on tissue injury. In spite of optimizing treatment parameters and conditions, each combination caused significant damage to the gastric wall. No acute perforations occurred. (c) Endoscopic YAG laser treatments were applied successfully. Efficacy and total energy requirements were compared with similar treatments previously done at laparotomy. (d) In an attempt to reduce tissue damage, the YAG laser was modified to produce a 1.3-microm wavelength. YAG laser treatment using this alternative wavelength caused more immediate damage than the 1.06 micron wavelength. From these studies we conclude: (a) YAG laser photocoagulation effectively stopped experimental gastric ulcer bleeding when applied both at laparotomy and endoscopy; (b) compared to untreated ulcers, YAG laser treatment caused significant tissue damage despite control of several important variables (power output, spot size, pulse duration, and coaxial CO2); (c) increased total energy, larger spot size, and longer pulse duration appeared related to increased tissue injury with YAG laser treatment; total energy was the single most important factor. (d) Successful hemostasis with endoscopic application of the YAG laser required more total energy than treatment of laparotomy. (e) Modification of the YAG laser wavelength to 1.3 microns did not reduce tissue injury.

Acute Disease↗