Vergleich des Verlaufs der neuromuskulären Blockade nach Applikation von Mivacurium bei Schulkindern unterschiedlicher Altersgruppen im Rahmen einer total intravenösen Anästhesie

Mivacurium has short acting properties which are unique in the group of non-depolarising muscle relaxant. It is the most common muscle relaxant in clinical anaesthesia for paediatric patients in Germany. There is sparse data about the effect of age on pharmacodynamic. The aim of this study was to elucidate the course of neuromuscular blockade at the adductor pollicis muscle after application of 0.2 mg/kg Mivacurium in school children of different age undergoing an interventions with total intravenous anaesthesia. The course of neuromuscular blockade at adductor pollicis muscle was recorded in 20 school children with age of 6 to 12 years, who underwent an elective paediatric surgical or paediatric urological operation. The children were assigned in two age groups (group JSK: age 6 – 7 years, n=10; group ASK: age 8 - 12 years, n=10). As expected, both age groups differed statistically significant by age, also by height and weight. The mean age in the JSK-group was 6 years and in the ASK-group 8 years, the mean weight was 20 kg respectively 41 kg and height 120 cm respectively 137 cm. The body-mass-index (BMI) with 15.0 (JSK-group) and 17.5 (ASK-group) showed no statistical difference between both groups. After inducing anaesthesia with propofol and remifentanil, the neuromuscular blockade was monitored after autocalibration and stabilisation of the signal with supramaximal transcutaneous stimulation of the ulnar nerve. Evoked acceleromyography at the adductor pollicis muscle was performed after application of Mivacurium 0.2 mg/kg (TOF-Watch SX). Lag-time, onset-time and peak-effect were measured, also T125%, T175%, T190%, TOF-ratio 0.7 and 0.9 as well as the recovery-index according to the GCRP-criteria of Copenhagen consensus conference and compared between both groups. Lag-time, onset-time and peak-effect exhibited no statistical significant difference between the JSK-group (mean lag time 45 sec, mean onset time 2.4 min and mean peak effect 100%) and ASK-group (mean lag time 45 sec, mean onset time 2.0 min and mean peak effect 100%). The results of this study lead to the conclusion, that there is no significant age-related influence in the course of neuromuscular blockade after application of Mivacurium 0.2.mg/kg for the age-group reviewed and with the use of TIVA. This result might be helpful for the estimation of the effect of Mivacurium in the context of TIVA.Mivacurium ist das einzige nicht-depolarisierende Muskelrelaxans mit kurzer Wirkdauer. Die Substanz ist in Deutschland das klinisch am häufigsten eingesetzte Muskelrelaxans bei pädiatrischen Patienten. Daten zum Einfluss des Alters auf die Pharmakodynamik von Mivacurium bei pädiatrischen Patienten sind rar. Ziel dieser Studie war es daher, den Verlauf der neuromuskulären Blockade am M. adductor pollicis nach Applikation von 0,2 mg/kg Körpergewicht (KG) Mivacurium im Rahmen einer Total intravenösen Anästhesie (TIVA) bei Schulkindern zu untersuchen Bei 20 Schulkindern, die sich einem elektiven kinderchirurgischen bzw. kinderurologischen Eingriff unterziehen mussten, konnte der Verlauf der neuromuskulären Blockade am M. adductor pollicis aufgezeichnet werden. Nach ihrem Alter erfolgte die Einteilung in die beiden Studiengruppen (Gruppe „Junge Schulkinder“ (JSK): 6-7 Jahre, n=10 bzw. Gruppe „Alte Schulkinder“ (ASK): 8-12 Jahre, n=10). Die zwei Gruppen unterschieden sich randomisierungsbedingt hochsignifikant hinsichtlich ihres Alters, sowie der Größe und ihres Gewichts. Das mediane Alter in der JSK-Gruppe betrug 6 Jahre und in der ASK-Gruppe 8 Jahre, das mediane Gewicht 20 kg bzw. 41 kg und die Größe 120 cm bzw. 137 cm. Der Body-Mass-Index (BMI) war mit 15,0 (JSK-Gruppe) bzw. 17,5 (ASK-Gruppe) zwischen beiden Gruppen vergleichbar. Nach Einleitung der Narkose mit Propofol und Remifentanil erfolgte das Monitoring des Verlaufs der NMB nach Autokalibration und Signalstabilisierung mittels supramaximaler transkutaner Stimulation des N. ulnaris und Aufzeichnung mittels evozierter Akzeleromyographie am M. adductor pollicis nach Applikation von 0,2 mg/kg KG Mivacurium (TOF-Watch SX). Dabei wurden Lag-time, Onset-time und Peak-effect, sowie T1 25%, T1 75%, T1 90%, TOF-Ratio 0,7 und 0,9 sowie der Recovery-Index gemäß den GCRP-Kriterien der Kopenhagener Konsensus Konferenz bestimmt und zwischen beiden Gruppen mittels MWU-Test verglichen. Die Lag-Time, Onset-Time und Peak-Effect wiesen zwischen der JSK-Gruppe mit im Median 45 sec, 2,4 min und 100% keine signifikanten Unterschiede zur ASK-Gruppe mit 45 sec, 2,0 min und 100% auf. Die Ergebnisse der vorliegenden Untersuchung lassen den Schluss zu, dass es bei Schulkindern keinen signifikanten altersbedingten Einfluss auf den Verlauf der neuromuskulären Blockade nach Applikation von 0,2 mg/kg KG Mivacurium unter TIVA gibt. Dieses Wissen kann klinisch hilfreich sein, um die Wirkung von Mivacurium unter TIVA besser einschätzen zu können

Connecting strongly correlated superfluids by a quantum point contact

Point contacts provide simple connections between macroscopic particle reservoirs. In electric circuits, strong links between metals, semiconductors or superconductors have applications for fundamental condensed-matter physics as well as quantum information processing. However for complex, strongly correlated materials, links have been largely restricted to weak tunnel junctions. Here we study resonantly interacting Fermi gases connected by a tunable, ballistic quantum point contact, finding a non-linear current-bias relation. At low temperature, our observations agree quantitatively with a theoretical model in which the current originates from multiple Andreev reflections. In a wide contact geometry, the competition between superfluidity and thermally activated transport leads to a conductance minimum. Our system offers a controllable platform for the study of mesoscopic devices based on strongly interacting matter.Comment: 5 pages, 4 figures, 7 pages supplementar

A scanning gate microscope for cold atomic gases

We present a scanning probe microscopy technique for spatially resolving transport in cold atomic gases, in close analogy with scanning gate microscopy in semiconductor physics. The conductance of a quantum point contact connected to two atomic reservoirs is measured in the presence of a tightly focused laser beam acting as a local perturbation that can be precisely positioned in space. By scanning its position and recording the subsequent variations of conductance, we retrieve a high-resolution map of transport through a quantum point contact. We demonstrate a spatial resolution comparable to the extent of the transverse wave function of the atoms inside the channel, and a position sensitivity below 10nm. Our measurements agree well with an analytical model and ab-initio numerical simulations, allowing us to identify a regime in transport where tunneling dominates over thermal effects. Our technique opens new perspectives for the high-resolution observation and manipulation of cold atomic gases.Comment: 5 + 6 pages, 4 + 5 figure

Connecting strongly correlated superfluids by a quantum point contact

Point contacts provide simple connections between macroscopic particle reservoirs. In electric circuits, strong links between metals, semiconductors or superconductors have applications for fundamental condensed-matter physics as well as quantum information processing. However for complex, strongly correlated materials, links have been largely restricted to weak tunnel junctions. Here we study resonantly interacting Fermi gases connected by a tunable, ballistic quantum point contact, finding a non-linear current-bias relation. At low temperature, our observations agree quantitatively with a theoretical model in which the current originates from multiple Andreev reflections. In a wide contact geometry, the competition between superfluidity and thermally activated transport leads to a conductance minimum. Our system offers a controllable platform for the study of mesoscopic devices based on strongly interacting matter.Comment: 5 pages, 4 figures, 7 pages supplementar

Entanglement Stabilization using Parity Detection and Real-Time Feedback in Superconducting Circuits

Fault tolerant quantum computing relies on the ability to detect and correct errors, which in quantum error correction codes is typically achieved by projectively measuring multi-qubit parity operators and by conditioning operations on the observed error syndromes. Here, we experimentally demonstrate the use of an ancillary qubit to repeatedly measure the $ZZ$ and $XX$ parity operators of two data qubits and to thereby project their joint state into the respective parity subspaces. By applying feedback operations conditioned on the outcomes of individual parity measurements, we demonstrate the real-time stabilization of a Bell state with a fidelity of $F\approx 74\%$ in up to 12 cycles of the feedback loop. We also perform the protocol using Pauli frame updating and, in contrast to the case of real-time stabilization, observe a steady decrease in fidelity from cycle to cycle. The ability to stabilize parity over multiple feedback rounds with no reduction in fidelity provides strong evidence for the feasibility of executing stabilizer codes on timescales much longer than the intrinsic coherence times of the constituent qubits.Comment: 12 pages, 10 figures. Update: Fig. 5 correcte