Biomedical subjects
A Tilgner
Publications and source records attributed to A Tilgner.
High-Rayleigh-number convection in spherical shells.
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Turbulence and internal waves in side-heated convection.
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Temperature and velocity boundary layers in turbulent convection.
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Boundary layer length scales in thermal turbulence.
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Temperature and velocity profiles of turbulent convection in water.
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Can chlorpromazine prevent flap necrosis?
The influence of chlorpromazine hydrochloride on failing, cranially-based dorsal flaps of female rats (Uje:WIST) was studied. The drug was injected subcutaneously into the abdomen pre- and postoperatively. The dosage was 1.5 mg/100 g preoperatively and 0.75 mg/100 g body weight every 12 hours following flap replantation for 10 consecutive days. No improvement in the survival rate was achieved by administration of chlorpromazine hydrochloride in this rat strain.
[Results of basic research in neovascularization of various types of flaps with and without microvascular anastomosis].
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[Neovascularization of the myocutaneous rectus abdominis island flap in the rat].
The neovascularisation was investigated in 51 rectus abdominis myocutaneous island flaps (1.5 x 3.0 cm) in rats (Uje: WIST) following ligation of the pedicle vessels (superior epigastric artery and vein) without and with incision of the cranial flap border. The ligation was done on the 3rd, 4th, 5th, and 7th postoperative day. The efficiency of the neovascularisation was estimated quantitatively on the 3rd, 5th, and 7th day after vascular ligation by measurement of the necrotic flap tissue. The findings are expressed in percent of the whole flap area. Vascular pedicle ligation on the 3rd or 4th postoperative day caused an average necrosis rate of 98% and 84% respectively. No flap survived in these experimental group. In case of pedicle vessel occlusion on the 5th postoperative day without incision of the cranial flap border all myocutaneous flaps survived, partly with focal loss of the epidermis. Placing the ligation after incision of the flap border on the 5th day an average necrosis rate of 34% was found, only 5 out of 11 flaps survived. All flaps (n = 9) remained viable following vascular pedicle ligation on the 7th postoperative day. It seems necessary to observe myocutaneous flaps carefully until the 14th postoperative day, because tissue damages due to vascular pedicle occlusion on the 4th day may become visible not before the 10th or 11th postoperative day. Opening of the myocutaneous flap borders between the 5th and 7th postoperative day should be avoided.
[Temperature determination of the skin surface for the estimation of blood supply disorders in myocutaneous island flaps of rats].
In rectus abdominis myocutaneous island flaps (3.0 x 1.5 cm) of rats (Uje:WIST) skin surface temperature was measured by an infrared pyrometer for monitoring flap viability following experimentally induced blood flow insufficiency. The insufficiency was caused by ligation of the pedicle vessels (epigastric superior artery and vein) on the 3rd, 4th, 5th and 7th d after flap replantation, and by occlusion of these vessels with microclips for 2 h. Only the temperature differences between the intact and the operated skin surface were used to estimate blood flow efficiency not, the absolute values. These differences were statistically insignificant between the intact right and left abdominal skin areas and between the intact skin and the vital flap surfaces. In these cases the maximal temperature differences were 0.52 degree C. Only during the early postoperative period (3-days ligation group) a correlation between blood flow insufficiency and flap viability is expressed by temperature differences (2.14 degrees C). Later on (7-days ligation group) a temperature difference of 1.87 degrees C was no evidence of disturbed wound healing. Thus in advanced stages in myocutaneous flaps differences of blood flow and neovascularization respectively cannot be estimated reliably by measurements of skin surface temperature. However, temperature differences greater than 2 degrees C signal impaired flap viability.
[Transcutaneous oxygen partial pressure in the evaluation of circulatory disorders in myocutaneous island flaps in the rat].
In rectus abdominis myocutaneous island flaps (3.0 x 1.5 cm) of 86 rats (Uje: WIST) transcutaneous oxygen tension measurements (tcPO2) were made by a Universal-PO2-Meter MO 10.1 (PRACITRONIC, Dresden, GDR) for monitoring flap viability following blood flow insufficiency produced experimentally. This insufficiency was induced by ligation of the pedicle vessels (superior epigastric artery and vein) on the 3rd, 4th, 5th and 7th day after flap reposition and by occlusion of these vessels with microclips for two hours. Only the tcpO2 differences between the intact skin and the contralateral myocutaneous island flap were used to assess effects on blood flow and not the absolute values. These differences were statistically insignificant between the right and left non-operated abdominal skin (0.24 +/- 0.11 kPa), the non-operated skin and the rectus abdominis myocutaneous island flap with intact pedicle vessels (group 2) (0.59 +/- 0.14 kPa) as well as flaps ligated at 5-days (0.71 +/- 0.18 kPa) in which vascular pedicle ligation were induced following incision of the cranial flap border. In the two-hour-ischemia group, the 3-days, 4-days and 7-days ligation groups the average tcpO2 differences were greater (1.17 +/- 0.40; 1.58 +/- 0.31; 1.24 +/- 0.22; 1.22 +/- 0.28 kPa) and statistically significant (p less than 0.05) in comparison to the myocutaneous flaps of group 2. Transcutaneous oxygen tension monitoring was useless in predicting flap survival in later postoperative blood flow insufficiency and in assessing the neovascularization. Only during the intraoperative manipulations or the early postoperative period (24 h) tcpO2 monitoring was valuable in assessing the blood supply of myocutaneous flaps in rats.
The influence of postoperative vessel occlusion on the viability of free microvascular skin-fat flaps and island flaps in rats.
Using a method of vascular pedicle ligation without skin incision, some minor differences were found between the progress of neovascularization in microvascular free skin-fat flaps and island flaps, both with and without 1-hr ischemia in rats. Viable flap areas were established following vascular pedicle ligation (both vessels or only artery or vein), on the third day after flap replantation in both island and free flaps. Vascular pedicle occlusion on the fifth day after operation resulted in complete survival of free flaps only. Island flaps survived completely following vascular pedicle ligation on the seventh postoperative day. A clear correlation existed between the timing of vascular pedicle ligation and the necrosis and shrinkage rates. In free flaps, clinical signs of viability disturbances were seen earlier in single or total vascular pedicle occlusions, on the third or fourth day compared with island flaps. Insufficiency of the pedicle vein in island or free flaps was tolerated earlier than arterial or total pedicle occlusion. Venous occlusion three days after flap replantation caused significantly higher necrosis and shrinkage rates (p less than 0.05) in free flaps than in island flaps.
Myocutaneous flap models in the rat. Anatomy, histology and operative technique of the latissimus dorsi myocutaneous flap.
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[Myocutaneous flap models in the rat. Anatomy, histology and preparation technic of the myocutaneous rectus abdominis flap].
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[Histopathology of the arterial wall after animal experiment microsurgical operations].
Histologic findings on microvessels of laboratory animals are reviewed. Lesions of the microvascular wall may be caused by preparation, microvascular clips and anastomosis. The intensity of the closing pressure of microclips as well as the clipping time influence the extent of the damage. Thrombosis of microarteries was not seen, even after a clipping time of 2 hours. The vascular lesions were reparable. Four different techniques of anastomosis used experimentally and clinically were compared: end-to-end suture anastomosis (absorbable and non-absorbable sutures), telescopic 2-suture anastomosis, sutureless telescopic adhesive anastomosis (fibrinogen, IMMUNO AG Wien), and telescopic 2-suture adhesive anastomosis. The tissue restitution was better in suture anastomosis carried out with absorbable sutures than performed with non-absorbable suture material. The sutureless telescopic adhesive anastomosis is a very gentle method, but the anastomoses are not always stable enough. The advantages of the telescopic 2-suture adhesive anastomosis (absorbable sutures, fibrinogen adhesive) are relatively small lesions of the vascular wall, good restitution and sufficient stability. The patency rate (96%) corresponds to that of the end-to-end suture anastomoses (94%). The clinical application of the telescopic anastomosis is estimated critically, and evidently it is more suitable for microarteries than for microveins.
The effect of inadequate venous or arterial blood supply on the survival of abdominal islands flaps in rats.
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[Suture and gluing technics in microvascular surgery. Comparative animal-experiment clinical studies].
In 135 femoral vessels of rats (70 arteries, 60 veins) end-to-end anastomoses performed, using 3 different methods (anastomoses with interrupted sutures, two-suture telescopic anastomosis, sutureless telescopic anastomosis with fibrinogen adhesive). The advantages and disadvantages of these methods were investigated and valued by clinical aspects (time of anastomosing, patency rate, complications). The results showed that a combined two-suture-telescopic anastomosis using absorbable suture material and fibrinogen adhesive is very stable and causes minimal lesions of the vessel wall, so that this method will be a nearly ideal anastomosing technique.
A new adhesive technique for microvascular anastomoses: a preliminary report.
A new technique is presented for the anastomosis of microvessels, using only a tissue adhesive (Fibrinkleber, Human-Immuno, produced by Immuno A. G. Vienna) without sutures. The feasibility of this technique is demonstrated experimentally on the femoral artery and vein in rats.