Standard diagnostic laparoscopy is superior to NOTES approaches: results of a blinded, randomized controlled porcine study.

BACKGROUND AND STUDY AIM: The use of transluminal endoscopic access via the stomach or colon for flexible diagnostic peritoneoscopy has been proposed, although the diagnostic value of the technique has not yet been fully clarified. In this animal trial, the two main natural orifice transluminal endoscopic surgery (NOTES) approaches - transgastric (TG) and transcolonic (TC) - were compared with standard transabdominal access using both rigid (TAR) and flexible instruments (TAF) for diagnostic laparoscopy. METHODS: A total of 48 peritoneoscopies were performed using two randomly assigned approaches in 24 anesthetized pigs. The ability of the examinations to detect 576 electrocautery markings simulating intraperitoneal metastases, to achieve complete organ visualization, and to simulate organ biopsies was analyzed. RESULTS: Sensitivities for the detection of lesions were 78.5 %, 59.7 %, 48.6 %, and 38.9 % for TAR, TAF, TC, and TG, respectively; standard laparoscopy was superior to all other approaches (P < 0.01). Among the NOTES approaches, TC was superior for examining the upper abdomen (P = 0.03). Complete organ visualization was better with the transabdominal approach (visual analogue scale TAR 7.15, TAF 6.71) than with the NOTES access routes (TC 5.07, TG 4.35); standard rigid laparoscopy was superior to both NOTES approaches (P < 0.01). Organ biopsy simulation was possible in 87 %, 85 %, 72 %, and 65 % of cases with TAR, TAF, TC, and TG, respectively. Standard rigid laparoscopy was again superior to both NOTES approaches (TAR vs. TC, P = 0.03; TAR vs. TG, P < 0.01). CONCLUSIONS: In this experimental trial, rigid standard laparoscopy provided better organ visualization, better lesion detection, and better biopsy capability than the transgastric and transcolonic NOTES approaches. In its current form, NOTES appears to be unsuitable for diagnostic laparoscopy.

Efficient design of multituned transmission line NMR probes: the electrical engineering approach.

Transmission line-based multi-channel solid state NMR probes have many advantages regarding the cost of construction, number of RF-channels, and achievable RF-power levels. Nevertheless, these probes are only rarely employed in solid state-NMR-labs, mainly owing to the difficult experimental determination of the necessary RF-parameters. Here, the efficient design of multi-channel solid state MAS-NMR probes employing transmission line theory and modern techniques of electrical engineering is presented. As technical realization a five-channel ((1)H, (31)P, (13)C, (2)H and (15)N) probe for operation at 7 Tesla is described. This very cost efficient design goal is a multi port single coil transmission line probe based on the design developed by Schaefer and McKay. The electrical performance of the probe is determined by measuring of Scattering matrix parameters (S-parameters) in particular input/output ports. These parameters are compared to the calculated parameters of the design employing the S-matrix formalism. It is shown that the S-matrix formalism provides an excellent tool for examination of transmission line probes and thus the tool for a rational design of these probes. On the other hand, the resulting design provides excellent electrical performance. From a point of view of Nuclear Magnetic Resonance (NMR), calibration spectra of particular ports (channels) are of great importance. The estimation of the π/2 pulses length for all five NMR channels is presented.

[Living donors in kidney transplantation. Renaissance by non-related donors?]. / Lebendspende bei Nierentransplantation. Renaissance durch nicht verwandte Spender?

Renal Transplantation is hampered worldwide by the continuing lack of cadaveric organs. The discrepancy between the number of patients on the waiting list and the number of organs available is further compounded by the still unresolved problem of chronic transplant failure. Against this background, the arguments for increasing acceptance of the use of kidneys from living donors, both related and unrelated, are discussed. Initial reports on appreciably improved transplant survival rates of organs from unrelated living donors (85% survival after 3 years [19]) have since been confirmed by more recent studies. Our own results, in part obtained during a prospective study involving 103 patients (53 related, 50 unrelated) done between October 1994 and April 1999, with strict psychological care/evaluation prior to and after transplantation, revealed a four-year transplant survival rate of 98% in both groups. So far, the higher rejection rate of 34% in unrelated, vs. 13.2% in related, donors has not led to any earlier chronic dysfunction of the transplant. The expanded use of living kidney donors is not only ethically justifiable, but also improves the outcome.

Ethics regarding living-donor organ transplantation.

During the last two decades, an intensive discussion has taken place in the field of medical ethics, which has lead to a reawakening of interest in the subject of living-donor organ transplantation and a re-evaluation of the moral problems related to it. In this process, traditional professional ethics have, to a large extent, been replaced by more complex modes of moral reasoning. The ethical principle of respect for the autonomy of persons has proven to be of prime importance in this field.