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Biomedical subjects

A Melzer

Publications and source records attributed to A Melzer.

At least 19 recordsLinked to original sources
PubMed1995

Effect of increased protein intake and nutritional status on whole-body protein metabolism of AIDS patients with weight loss.

The aim of this study was to investigate nutritional status and protein metabolism during total parenteral nutrition (TPN) in AIDS patients with weight loss. Six patients on treatment for AIDS-associated complications were investigated and reviewed TPN that supplied energy equivalent to 1.5 times the resting energy expenditure (REE). Amino acid (AA) supply increased from 0.6 g/kg body weight (BW)/d on days 1 to 3 and 1.2 on days 4 to 6 to 1.8 on days 7 to 9. Nonprotein energy was given as equicaloric amounts of glucose and fat emulsion. There were repeated measurements of nitrogen balance and whole-body protein turnover (WBPT) using a bolus 15N-glycine method on the morning of days 3, 6, and 9. Principal findings were as follows: (1) increasing the supply of AAs significantly improves nitrogen balance in AIDS patients; (2) there is no simple linear effect of increasing amounts of AAs on WBPT in AIDS patients; (3) WBPT is high and variable in these patients; and (4) mean WBPT of each patient is significantly correlated with body cell mass (BCM) as a proportion of BW (P < .001, r = .92). We conclude that poor nutritional status in AIDS patients with weight loss is associated with high WBPT. However, these patients can attain at least transiently positive nitrogen balance with sufficient protein intake, predominantly through an increase in whole-body protein synthesis (WBPS).

Acquired Immunodeficiency Syndrome↗
PubMed1995

Endoscopically controlled trocar and cannula insertion.

One of the keys to safe laparoscopic or thoracoscopic surgery is an expeditious and reliable access to the region of interest. To minimise the risk of accidental injury to major vessels, lung, intestine and other important structures the principle of controlled visualised access has been advocated. This has led to several developments in the field of trocars, cannulae and puncture techniques. Examples are the insertion of a needle scope into a Veress needle, complex access cannulae and our new principle of using an "optical scalpel". The direct visualisation of an active, controllable penetration of the abdominal wall is expected to become indispensable. A selected variety of endoscopically assisted trocar and cannula systems such as the "windowed trocar", the "optical trocar", the "Visiport" and the "optical scalpel" are described.

Catheterization↗
PubMed1995

Image-guided access techniques.

For increasing safety in access and guidance of endoscopes and instruments, fast real-time radiologic imaging should be integrated. Open designed Magnetic Resonance Imaging (MRI), Computer Tomography (CT), and Electron Beam Tomography (EBT) scanners permit adequate transparency of the operative field. CT and EBT as hybrid scanners can be combined with fluoroscopy. MRI avoids X-ray exposure and entails the possibility of 3D localisation, while open access and keyhole imaging allows nearly real-time guidance of instruments. EBT has the largest gantry (90 cm) for using long instruments, and the image acquisition requires only 50 msec (34 images/sec at 8 levels). However, computed reconstruction of the data takes about 3 times longer than conventional CT. Until EBT can be accelerated, CT will be the golden standard of guidance-techniques in high risk areas, because the tips of the instruments can be precisely visualised within +/- 0.5 mm (MRI: 3.5 mm). MRI-guidance can be used for low risk access techniques. This safe interactive transparent guidance technique has the potential to reduce complications, and it adds significant advantages to micro-invasive operative procedures such as percutaneous diskectomies, pain and cancer therapy with ethanol, or gene-technology implants in the new field of "surgical tomography".

Diagnostic Imaging↗
PubMed1994

Future trends in endoscopic suturing.

This paper deals with future aspects and developments in endoscopic sutures, needles, needle drivers, and sewing devices. Shape memory alloys such as superelastic nickel-titanium can be used for surgical needles and hingeless needle drivers. A sewing device consists of a T-Needle which can be shuttled between the jaws of specially designed instruments. The jaws possess small elements that grip the needle tips. The "Needle Rotor" facilitates intracorporeal swivelling and positioning of the needle because one jaw can be moved longitudinally over the other. A new "cutting knot pusher" permits immediate cutting of a slip knot subsequent to tightening.

Anastomosis, Surgical↗
PubMed1994

Principles of ultrasound imaging.

Ultrasound imaging is a process involving the real-time interaction of the physician with both the imaging equipment and the tissue. A good understanding of the physical principles involved in creating the image will ensure optimal handling of the equipment and proper interpretation of the resulting image.

Equipment Design↗
PubMed1993

Experimental development in colorectal surgery.

A one year research programme on endoscopic colorectal resections was carried out at the University of Tübingen. Two research lines were planned: the development of the required technologies and the development of the surgical procedure. During the research programme on technologies a new device provided with an air proof system for transanal insertion of the anvil of a divisible stapler and a new technique for closure of the colonic and rectal stumps (cable binding technique) were developed. Such technological innovations enabled the authors to accomplish a new combined laparoscopic-rectoscopic procedure which was performed according to four different variants in a series of 32 animals. The last 15 consecutive successful cases, performed according to the definitive procedure, represented a standardized animal trial before starting the clinical investigation.

Anastomosis, Surgical↗
PubMed1993

3-D video techniques in endoscopic surgery.

Three-dimensional visualisation of the operative field is an important requisite for precise and fast handling of open surgical operations. Up to now it has only been possible to display a two-dimensional image on the monitor during endoscopic procedures. The increasing complexity of minimal invasive interventions requires endoscopic suturing and ligatures of larger vessels which are difficult to perform without the impression of space. Three-dimensional vision therefore may decrease the operative risk, accelerate interventions and widen the operative spectrum. In April 1992 a 3-D video system developed at the Nuclear Research Center Karlsruhe, Germany (IAI Institute) was applied in various animal experimental procedures and clinically in laparoscopic cholecystectomy. The system works with a single monitor and active high-speed shutter glasses. Our first trials with this new 3-D imaging system clearly showed a facilitation of complex surgical manoeuvres like mobilisation of organs, preparation in the deep space and suture techniques. The 3-D-system introduced in this article will enter the market in 1993 (Opticon Co., Karlsruhe, Germany.

Animals↗
PubMed1993

Visually controlled trocar insertion by means of the "optical scalpel".

The importance of a safer approach to the abdominal cavity has led to several developments in the field of trocars, cannulae and puncture techniques. Examples are the insertion of a needle scope into a Veress needle, complex access cannulae and our new principle of using an "optical scalpel". In our view, direct optical visualization and actively controllable penetration of the abdominal wall are mandatory. First experimental and clinical applications indicate the newly developed "optical scalpel" (Olympus Winter & Ibe, Hamburg, Germany) as a reliable and useful instrument for a safe approach to the endoscopic operative field. This instrument was successfully used in 10 endoscopic operations and is currently undergoing further clinical testing.

Abdomen↗
PubMed1993

Lasers.

Explore the source record for details and available documents.

Laser Therapy↗
PubMed1993

Medicus and technicus.

Throughout history "medicus" and "technicus" worked closely in the design of surgical instruments. The early tools were relatively primitive in modern terms but most of them achieved the purpose for which they were designed. In recent centuries numerous surgical instruments were pioneered to execute a variety of tasks. As surgical and technical skills developed some instruments were modified while others were abandoned. Many instruments used in conventional open surgery have obviously stood the test of time, though they have been continuously adapted to the current requirements, the available surgical skills and preference. More recently instrument design and manufacture has been taken over by industry. There are a variety of reasons as to why this may have been an important and advantageous step but the main disadvantage lies in the reduction in the cooperation between "medicus" and "technicus".

Biomedical Engineering↗
PubMed1993

Intelligent surgical instrument system ISIS. Concept and preliminary experimental application of components and prototypes.

The recent progress in endoscopic surgery, which is highlighted by the complexity of fundoplication, stomach surgery and colorectal surgery, has revealed major restrictions with difficult surgical manipulations. Mobilisation, dissection and suturing techniques are hampered mainly by the limited degrees of freedom of the conventional rigid instruments (translation along and rotation around the longitudinal axis and the limited play in the access channel). The frequent interchange of instruments such as coagulation forceps, scissors and suction-irrigation probe is time-consuming. We have established an interdisciplinary development model with the aim of improving surgical technology, instrument systems, the operation theatre and its environment. Concepts of electronic instrument control and sensoric feedback, and the features of the surgical man-machine-interface are described. The first prototypes of an intelligent steerable instrument system, ISIS, and its optional effectors, e.g. semiautomatic sewing device and multifunctional coagulation instrument, were tested in phantom and animal experiments. System analysis will lead to specially designed operating theatres (minimal invasive surgical operating system MINOS).

Dissection↗
PubMed1991

[Laparoscopic cholecystectomy: new evaluation of a surgical method in the light of endoscopic techniques].

The laparoscopic cholecystotomy was developed to remove calculi while preserving a functioning gallbladder. 120 phantom tests on pig's gallbladders were performed. No major complications were observed in 20 animal experiments with pigs. Compared with competing conservative and interventional methods the laparoscopic cholecystotomy provides immediate removal of stones and a definite closure of the gallbladder by a clip. Calcified stones are no contraindication for the procedure. After introduction into the clinical routine, an outpatient treatment in local anaesthesia seems to be possible. Patients with a high operative risk should be treated by this method. The laparoscopic cholecystotomy represents an alternative to the percutaneous transhepatic litholysis and the ESWL.

Anesthesia, Local↗
PubMed1991

Experimental laparoscopic cholecystotomy.

This instrument set for a single puncture technique of laparoscopic cholecystotomy was developed in 100 phantom tests with pig gallbladders and was later evaluated in 12 animal experiments. No complications were observed. After clinical development, treatment on an outpatient basis under local anaesthesia seems possible. For the patient this would mean avoiding general anaesthesia, shorter hospitalization, pain reduction and good cosmetic results, while reducing expenditure for the public health authorities at the same time. To avoid recurrent stones, diet and low-dose drug therapy should be considered. Because the procedure is minimally invasive, repetition of the laparoscopic procedure seems justified if stones recur.

Animals↗
PubMed1990

[Endoscopic microsurgical dissection of the esophagus: a contribution to the reduction of pulmonary complications following esophageal resection? A comparative animal experiment study].

A new endoscopic microsurgical technique for dissection of the esophagus has been developed and tried out in animals. With this technique the esophagus is dissected and removed via a cervical approach by means of a new operating endoscope. In a randomized animal study we compared endoscopic versus blunt dissection and versus abdominothoracic resection. During endoscopic dissection we saw significantly lower bleeding and no laceration of the pleural cavity or damage to the recurrent laryngeal or to the vagus nerve. Significant changes of hemodynamics or gas exchange were observed in the blunt dissection group: increase of heart frequency, decrease of arterial pressure and decrease of paO2. In contrast these parameters did not change in the endoscopic group.

Animals↗
PubMed1989

Endoscopic microsurgical dissection of the esophagus. Results in an animal model.

Blunt dissection of the esophagus is considered the least invasive technique in the treatment of either benign or malignant diseases of the esophagus. Its disadvantage is that it has to be carried out blindly. The results may be uncontrollable hemorrhage, unrecognized injuries to the trachea, and damage to the recurrent laryngeal nerve. In order to reduce the degree of invasiveness a new endoscopic microsurgical technique for the dissection of the esophagus has been developed and tried out in animals. This paper presents the operative technique. Our new endoscopic microsurgical technique obviates a thoracotomy, while direct endoscopic vision results in improved dissection. The magnified endoscopic view permits selective exposure of blood vessels and prevents injury to the adjacent organs.

Animals↗