Biomedical subjects

H G Machens

Publications and source records attributed to H G Machens.

48 records · Page 3Linked to original sources

PubMed1995

[Updated status of replantation services in Germany, Austria and Switzerland].

The revised survey involves the years 1991 and 1992 and includes 41 university and major civil hospitals. As in the years 1989 and 1990, replantation activity in the year 1991 still declined, whereas in 1992 we registered a sharp increase in replantations, especially in Germany. In numbers, 856 were reported for 1991 (72 macro- and 784 microreplantations), and 1091 in 1992 (85 macro- and 1006 microreplantations). A considerable number of amputation cases (617) were rejected mainly due to lack of operative manpower capacity.

Austria↗

PubMed1995

Approaches to postoperative blood flow monitoring after free tissue transfer. Which is the best?

Success rates for free tissue transfer (FTT) have greatly improved over the last 20 years, partly due to improved technical performance of microvascular anastomoses with better optical and instrumental aids. However, flap failure is still a clinical problem and occurs in 5-10%, mainly due to blood vessel thrombosis within the first 24 postoperative hours. Salvation rates of failing FTT can be optimized by the prompt diagnosis of irreversibly compromised tissue blood flow and immediate operative reexploration. Therefore, there is a special demand for adequate and reliable postoperative monitoring techniques. This article gives an overview of all monitoring techniques, which have been performed both in the experimental and clinical setting after FTT thus far.

Anastomosis, Surgical↗

PubMed1994

Routine monitoring in patients with free tissue transfer by laser-Doppler flowmetry.

The use of laser Doppler flowmetry (LDF) was tested in 108 consecutive patients, who underwent free tissue transfer at our institution between December, 1988, and June, 1990. Sixteen patients (14.8%) suffered vascular complications, which could be detected in all cases earlier by LDF than by clinical examination alone. LDF therefore prompted faster surgical intervention in these cases, allowing flap salvation in 9.3% (n = 10). Difficulties had to be noted in diagnosing venous thrombosis by means of the LDF due to sometimes unspecific alterations in LDF signals. Technical improvement of LDF might lead to a higher diagnostic accuracy if venous thrombosis occurs.

Adolescent↗

PubMed1994

Techniques of postoperative blood flow monitoring after free tissue transfer: an overview.

Ever since free tissue transfer has been established in microsurgery, success rates have greatly improved over the years, partly due to improved technical performance of microvascular anastomoses with better optical and instrumental aids. However, flap failure still occurs in 5-10%, mainly due to blood vessel thrombosis within the first 24 postoperative hours. Salvation rates of failing free tissue transfers can be optimized by in-time diagnosis of irreversibly compromised tissue blood flow and immediate operative reexploration. Therefore, there is a special demand for adequate and reliable postoperative monitoring techniques. This article gives an overview of all monitoring techniques, which have been performed both in the experimental and clinical setting thus far.

Body Temperature↗

PubMed1994

[Gamma nail osteosynthesis of per- and subtrochanteric femoral fractures. 4 years experiences and their consequences for further implant development].

The Gamma nail can be used in all types of per- and subtrochanteric fractures because of its biomechanical characteristics. In this prospective evaluation of our 330 patients treated between November 1989 and November 1993 the usefulness of the Gamma nail for the osteosynthesis of all types of fracture was evaluated. The rate of intraoperative and postoperative complications but also gait function, postoperative weight bearing, general complications, and survival were analysed. We compared the results of four therapy periods to evaluate the importance of the expertise of the surgeon and the 'learning curve'. The Gamma nail osteosynthesis was performed in 72-98% in unstable per- and subtrochanteric fractures. The nail diameters used shifted to the 12 mm nail (99%) and the 130 degrees angle (93%) in the fourth examination period. The intraoperative complication rate is highly dependent from the expertise of the surgeon and the experience with the system. The rate decreased from 42.2% in the first to 17.2% in the fourth examination period. The most important complications were: additional fractures (1.7%), distal locking screw problems (7%), femoral head rotation (2,4%), and not sufficient fracture reduction (4.1%). Whereas in general these did not influence the postoperative management the use of a too short femoral neck screw lead to instability. Postoperative local complications were: rotation of the femoral head and neck (0.6-5.5%), related to the gliding of the neck screw (0.6-4%), fracture at the end of the nail (1.8-4%), fatigue break of the nail (1 case) and hematoma (1.2-8.3%). In all these cases reoperation was needed. To reduce the rate of intra- and postoperative complications a new gliding nail (GN) is presented. Due to the double T-profile of the femoral neck blade the implant is stable for neck rotation. The blade has a collar which makes it impossible to implant the blade to deep in the femoral neck. The larger nail profile at the femoral neck perforation reduces the risk of implant failure. The implant can be used as dynamic compression as well as static implant both in the direction of femoral neck and shaft.

Aged↗

PubMed1994

A new procedure for abdominal wound closure after pediatric liver transplantation: the "sandwich" technique.

Primary wound closure cannot always be achieved after pediatric liver transplantation (LTx). This may be due to lack of intraabdominal space from postanhepatic small bowel edema or oversized grafts despite partial LTx. For those instances we developed the "sandwich" technique. This procedure incorporates advantages of previous techniques with some additional advantages described herein. Use of polyglactin 910/silicone meshs in a sandwich fashion allows for one-stage permanent abdominal closure without major loss of body plasma fluids after pediatric LTx. So far our clinical experience with this technique has been very satisfying.

Abdomen↗

PubMed1993

Use of the hydrogen clearance technique for measurements of pancreatic blood flow.

The hydrogen clearance technique (HCT) was employed for measurements of local pancreatic blood flow (PBF) in dogs, opossums, and rats under normal conditions and in opossums during biliary pancreatitis. Local PBF (ml/min/100 g) in dogs was 57.6 +/- 10.4, in opossums 60.6 +/- 9.5, and in rats 144.7 +/- 23.4, under resting conditions. Regional distribution of local PBF in dogs showed no statistical differences. Technical aspects of the HCT were described in detail. Under physiological conditions parenchymal trauma following electrode implantation was negligible in nearly all cases. More than 95% of registered clearance curves were monoexponential and showed excellent reproducibility of PBF values in repeated measurements (percentage deviation < or = 6.7). Five days after initiating biliary pancreatitis by common channel ligation in opossums local PBF was 72.1 +/- 14.7 after implantation of new electrodes. Chronically implanted electrodes, however, recorded only 39.7 +/- 15.8, due to massive fibro-proliferative alterations around the implanted electrode tips. We therefore conclude that the HCT as described is a useful tool for measuring local PBF in acute experimental settings only. Biliary pancreatitis in our model causes no significant alterations of PBF after 5 days.

Animals↗

PubMed1993

Is the hydrogen clearance technique a useful tool for measurements of pancreatic blood flow during acute experimental pancreatitis?

Changes of pancreatic blood flow (PBF) during acute pancreatitis (AP) have been under investigation by means of electromagnetic flowmeters, radioactive microspheres, isotope fractionation, radioactive gas clearance, and venous outflow techniques. All methods, however, have certain drawbacks, which make the application of other techniques desirable. In this study, the hydrogen clearance technique (HCT) was tested for the first time in a well-established foxhound model of AP. PBF, systemic blood pressure, and heart rate were monitored over 90 min after the onset of AP and 60 min after therapeutic infusion of Dextran-40 (10 ml/kg body wt). Our results fully agree with the data found by other techniques in this experimental model. Sixty-five of 73 electrodes implanted into the pancreas of eight foxhounds were found working. From 1,024 registered clearance curves, 876 were identified as monoexponential. In the other cases, and only then, we found either dislocation of the electrode tips (n = 6) or perielectrodal hemorrhage during histological examination (n = 4). We believe that the HCT is a feasible and reliable tool for measuring PBF in experimental settings like AP.

Acute Disease↗

PubMed1992

Bilateral elastofibroma dorsi.

Elastofibroma dorsi was diagnosed in a 76-year-old woman with bilateral subscapular tumor masses and a 3-year history of recurrent, right-sided scapular pain. A bilateral tumor extirpation was performed and the patient left the hospital free of symptoms 10 days later. We suggest that both constant trauma with resulting excessive elastin production and collagen degeneration might play a major role in the pathogenesis of this rare proliferative lesion.

Aged↗

PubMed1992

Advantages and disadvantages of using the hydrogen clearance technique to measure pancreatic blood flow.

This study was undertaken to identify the advantages and disadvantages of using the hydrogen clearance technique (HCT) to measure pancreatic blood flow (PBF) in the opossum over short and long periods. An open study was performed on 8 opossums. A total of 72 platinum electrodes were implanted into the pancreas. On the fifth day 41 additional electrodes were implanted. All implantation sites were examined histologically after five days. Measurements of pancreatic blood flow were taken every other day for five days. Three measurements were taken from each electrode and the mean of the three was used for analysis. In the anaesthetized animal mean PBF (SD) was 63.5 (12.8) ml min-1 100 g-1 immediately after electrode implantation and 34.3 (11.4) ml min-1 100 g-1 on the 5th postoperative day. Of the implanted electrodes, 35% failed during the experimental course, mainly as the result of proliferation of scar tissue around the electrodes. Mild to moderate fibroproliferation had taken place around the platinum tips of the remaining 65%. Primary electrode implantation caused no or negligible trauma to the pancreas. We recommend the HCT only for short-term measurements of PBF. Implantation of electrodes for any length of time leads to inflammatory changes around the platinum tips that cause proliferation of scar tissue and lead to failure of the electrodes, misleadingly low PBF recordings, and fewer monoexponential clearance curves.

Animals↗

PubMed1988

Autoregulatory capacity and the effect of isovolemic hemodilution on local cerebral blood flow.

The effect of isovolemic hemodilution with dextran 40 on local cerebral blood flow was measured in eight cats by means of the hydrogen clearance technique. Under normotension the decrease of hematocrit from 35% to 25% causes a sudden increase of up to 30% in local cerebral blood flow. After lowering the mean arterial blood pressure from 140 to 80 mm Hg, hemodilution did not alter cerebral blood flow significantly. From this observation it is concluded that the increase of cerebral blood flow following hemodilution is caused by compensatory vasodilatation and not by reduction of blood viscosity. This could imply that hemodilution cannot improve blood flow in areas of impaired autoregulation.

Animals↗

PubMedDate not supplied

Procalcitonin as a marker for the early diagnosis of severe infection after thermal injury.

High serum concentrations of procalcitonin (PCT), the 116 amino acid precursor protein of the hormone calcitonin, have been found in patients with various bacterial infections, particularly in those with sepsis. Because recent reports have shown that serum PCT constitutes a useful parameter for the diagnosis of sepsis in patients with several clinical conditions, a temporal analysis of the PCT concentrations in the plasma of 19 patients with severe burns (median body surface area burned, 32%) was conducted retrospectively. Nine patients were classified as septic on the basis of standardized clinical and laboratory parameters. Compared with the nonseptic group, these patients showed higher plasma PCT throughout the study period (median concentrations of septic vs nonseptic patient groups: 0.4 vs. 0.2 microg/L on postburn day 2; 1.0 vs. 0.3 microg/L on postburn day 4; 5.5 vs. 0.3 microg/L on postburn day 7; 10.8 vs. 0.5 microg/L on postburn day 9; 4.2 vs. 0.4 microg/L on postburn day 12; and 1.7 vs. 0.5 microg/L on postburn day 14), with differences considered to be significant (P<.05) from day 7 on. In contrast, differences in the plasma C-reactive protein concentrations were less pronounced and never reached statistical significance. PCT concentrations exceeding 15 microg/L were only observed in the 3 patients who died of sepsis-induced multiple organ failure. In addition to absolute PCT, individual time courses were also of diagnostic value. PCT is a highly efficient laboratory parameter for the diagnosis of severe infectious complications after a burn injury.

Adult↗