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Biomedical subjects

W Waidelich

Publications and source records attributed to W Waidelich.

At least 19 recordsLinked to original sources
PubMed1990

Krypton filled flashlamp: a possible new light source for near infrared spectroscopy in vivo.

We have designed a reliable and flexible low cost instrument for NIR spectroscopy. A krypton filled flashlamp was used as inexpensive light source. Providing a number of suitable emission peaks in the NIR, this flashlamp is ideal for NIR spectroscopy. Application to other NIR spectroscopy systems, e.g. to CCD (Charge Coupled Device) spectrophotometers, should be possible. The introduced system was tested on human arm tissue during arterial occlusion. Results equivalent to those described by other authors could be obtained by this new technical approach.

Adult↗
PubMed1988

[The CO2 laser in dermatotherapy--use and indications].

Due to the high absorption of infrared light in water the CO2 laser (lambda = 10,600 nm) is suitable for cutting and vaporizing tissue. The ablation of pathological tissue by means of the CO2 laser can be exactly controlled. The treated area is usually dry and clear since blood and lymph vessels up to a diameter of 1 mm are sealed. Postoperative swelling and pain are reduced compared with electrosurgery. Important and frequent indications for CO2 laser application are HPV papillomas (condylomata acuminata, common warts, bowenoid papules) and the removal of tattoos. The CO2 laser is also suitable for the removal of benign and disseminated lesions such as angiofibromas, syringomas, trichoepitheliomas, epidermal nevi etc. Lesions of the oral mucosa (leukoplakias, mucosal warts) can be removed by means of the CO2 laser. Additionally, the treatment of vascular lesions (nevi flammei, lymphangiomas, telangiectasias) has been described, although the CO2 laser does not operate in a vessel-specific manner. As this review article demonstrates, the CO2 laser has a broad range of applications and represents an enrichment of dermatotherapy.

Humans↗
PubMed1987

Comparison of the maximum coagulation depth in human skin for different types of medical lasers.

The values for the maximum coagulation depth (MCD) of various types of lasers which are specified in the literature are not comparable, because often different irradiation times were used. MCD depends not only on the wavelength of laser light, but also on the time of action of the laser beam, because of heat transfer. In excised human skin MCD was determined histologically for irradiation with the argon laser, Nd:YAG laser, and CO2 laser. Extending the irradiation time from 0.2 s to 10 s results in a 4-6-fold increase in MCD. Coagulation experiments performed with a soldering iron have shown results similar to those obtained with the CO2 laser. Enlargement of the laser-beam diameter from 1 to 2 mm leads to a 50% increase in MCD. Additional chilling of the skin with water during laser irradiation protects the skin from evaporation, and the values for MCD increase to 3.5 mm for the argon laser and 5.5 mm for Nd:YAG laser. Detailed knowledge of the MCD is necessary to obtain the desired therapeutic effect, and also to avoid unwanted effects.

Connective Tissue↗
PubMed1987

[Treatment of naevi flammei with the argon laser].

We report on 901 patients with port wine stains treated by means of an argon laser. The treatment results have been definitively evaluated in 371 patients. They were significantly influenced by the patients' age and by the colour of the lesions. The worst response to the therapy was seen in pink port wine stains in children and juvenile patients (20% good results), in contrast to red and purple lesions in adult patients (80% excellent and good results). The size of the port wine stains did not significantly influence the treatment results, but in extensive lesions homogeneous lightening could not usually be attained and treatment often extended over some years. Port wine stains in the head and neck area responded best to therapy, and lesions on the legs, worst. Altogether, in 60%-70% of adult patients excellent or good results were obtained, the lesions being completely removed or significantly lightened and reduced in size. The side-effects of laser therapy were scar formation (7.3%) and changes in pigmentation (8.6%).

Adolescent↗
PubMed1986

Effects of argon, dye, and Nd:YAG lasers on epidermis, dermis, and venous vessels.

The aim of the present study, which was performed at the dorsal aspects of the ears of guinea pigs, was to compare effects of different lasers on epidermis, dermis, and small venous vessels. Irradiations were performed with argon, dye, and Nd:YAG lasers. In the first series tissue repair processes were studied after argon laser application. Laser defects were excised after 1, 4, 8, and 14 days and were prepared for routine histological examination. The breadth of epidermal defect and extent of dermal coagulation and occlusion of vessels by thrombus formation were examined histologically. In a second series parameters of irradiation (ie, exposure time, laser power) of the three different lasers were changed systematically. Laser-induced morphological tissue changes could be best observed 24 hours after irradiation. Each of the lasers led to occlusion of vessels by thrombus formation and also coagulated epidermis and dermis. The extent of dermal and epidermal coagulation was less pronounced after dye laser application. Using short exposure times it was possible to reduce the extent of epidermal damage caused by argon and Nd:YAG lasers. Only 50-msec dye laser pulses led to intravascular thrombus formation without epidermal and dermal damage.

Animals↗
PubMed1986

Neodymium-YAG laser therapy for vascular lesions.

Three patients with port-wine stains with a nodular surface, one patient with macrocheilia resulting from a port-wine stain, and one patient with a capillary hemangioma were treated with a Nd-YAG laser (mediLas, MBB-AT, Munich). Irradiance was between 800 and 1,600 watts/cm2, with energy fluence between 400 and 1,600 joules/cm2. Treatments were performed with local anesthesia on an outpatient basis. In all patients, marked improvements could be obtained after only a few treatments. Histologically there was necrosis of epidermis and dermis immediately after laser application, and ectatic vessels contained coagulated erythrocytes. Depth of coagulation was up to 3.5 mm. Quick restoration of epidermis was observed. After some days, macrophages, fibroblasts, and capillary blood vessels grew into the agglutination thrombi and ectatic vessels were replaced by granulation tissue and, later, by fibrous tissue. In comparison with the argon laser, the Nd-YAG laser coagulates at a much deeper level, but processes of tissue repair take longer and fibrosis is more pronounced after Nd-YAG laser application. Clinically, therefore, scar formation is more likely. Chilling the skin surface during irradiation and shorter exposure times may be effective in reducing the risk of scar formation in the future.

Adult↗
PubMed1986

Laser therapy of bowenoid papulosis and Bowen's disease.

Six patients with bowenoid papulosis and two patients with Bowen's disease of the genital area were treated by means of an argon, Nd:YAG, and CO2 laser. In all of the patients, complete resolution of the lesions was achieved. Due to a superficial coagulating effect, application of the argon laser should be restricted to macular and papular pigmented lesions. In contrast, Nd:YAG and CO2 lasers could be used even for treatment of extensive leukoplakia-like and verrucous lesions. Advantages and disadvantages of these two lasers are discussed.

Adult↗
PubMed1985

Treatment of benign, semimalignant, and malignant skin tumors with the Nd:YAG laser.

Reported are first experiences with Nd:YAG laser treatment of benign, semimalignant, and malignant skin tumors in 90 patients. Treated lesions included condylomata acuminata, basal cell carcinomas, solar keratosis, squamous cell carcinomas, and secondary malignant skin tumors. First clinical and histological results are promising, but long-term follow-up is required to judge the definite efficacy of this therapeutical modality.

Basal Cell Carcinoma↗
PubMed1984

Laser therapy of venous lakes (Bean-Walsh) and telangiectasias.

In 18 patients, venous lakes, and in 77 patients, telangiectasias were successfully treated with the argon laser. Because treatments were easy to perform and patients were not impaired by therapy, the argon laser is the treatment of choice for these conditions in our experience.

Adult↗
PubMed1984

Argon laser therapy of verrucous nevi.

In one patient afflicted with a systemic verrucous nevus, a marked improvement was obtained by repeated treatments with an argon laser. In two patients it was possible to remove localized verrucous nevus completely. There was no recurrence in the follow-up of 8 and 14 months, respectively.

Adult↗
PubMed1984

A three-year experience with the argon laser in dermatotherapy.

Since January 1980, 477 patients were treated with an argon laser, 337 afflicted with vascular lesions and 140 with nonvascular lesions. Laser therapy of portwine stains gave good results in 70% of the adult patients, but it was disappointing in patients younger than 18 years of age. Other vascular lesions, such as telangiectasia, venous lake, angiofibroma, lymphangioma, and cherry angioma, were also treated with success. For the removal of tattoos the argon laser is not an optimal modality. In our experience it should only be used in skin areas, where dermabrasion cannot be performed. Therapy of epidermal nevi, xanthelasma of the eyelids, verrucae, vulgares , and sebaceous gland hyperplasia gave preliminary promising results in some patients.

Adult↗
PubMed1983

[Treatment of zoster, post-zoster pain and herpes simplex recidivans in loco with laser light].

Red light of a krypton laser (lambda = 647 nm) was used for treatment of patients suffering from herpes zoster (n = 4), postherpetic neuralgias (n = 8) and herpes simplex recidivans in loco (n = 13). The afflicted skin was irradiated daily for ten days (laserpower 50 mw, exposure time 90 sec). Improvement was observed in 7 out of the 12 patients suffering from herpes zoster and postherpetic neuralgias respectively, and in 8 out of 13 patients afflicted with recurrent herpes simplex.

Aged↗
PubMed1983

[Morphologic studies in the treatment of nevus flammeus with argon laser].

Immediately after the argon laser impact one finds necrosis of epidermis and superficial dermis. Dilated vessels down to a depth of 0.8 mm are filled with coagulated erythrocytes. After 2 days there is initial restoration of epidermis, and dilated vessels are filled with agglutination thrombi. With and after the 6th day fibroblasts and capillary blood vessels grow into the thrombi, and later on vessels are completely replaced by granulation tissue and after 2-4 weeks by newly formed fibrous tissue.

Adult↗
PubMed1982

[Treatment of circumscribed lymphangiomas with the argon laser].

Six patients suffering from lymphangioma circumscriptum neviforme and two from lymphangioma circumscriptum localisatum were treated with an argon laser. Lymphangiomas regressed in all patients, with some scar formation. In four of the six neviform lymphangiomas there was recurrence of tiny clear pseudovesicles within 3-4 months following the first treatment. Two patients with localized type and two with neviforme type were without recurrence within 1 year following the first irradiation. A cure of extensive lymphangioma circumscriptum is not possible in our experience. Most of the patients were content with the obtained regression and accepted the slight scar formation and repeated treatments. Laser therapy for cosmetical reasons is not indicated.

Adolescent↗