Experience with the Avalon® bicaval double-lumen veno-venous cannula for neonatal respiratory ECMO.

OBJECTIVE: We report a single centre experience of neonatal respiratory ECMO using the Avalon® double-lumen venous cannula and compare it with reports in the literature. RESULTS: Between 2008 and 2012, the Avalon® cannula was used in 72 neonates: median age at cannulation was 1.8 days (IQR 1.2-2.8 days) and bodyweight 3.4 Kg (3.0-3.7 Kg). Meconium aspiration syndrome (61.1%), persistent hypertension of the newborn (25%) and congenital diaphragmatic hernia (5.6%) were the most common diagnoses. Complications occurred in 19 patients (26.4%): cannula site bleeding in 6 (8.3%), the cannula perforating the right atrial wall and requiring emergency midline sternotomy in 5 (6.9%) and the cannula needing repositioning in 3 (4.2%). Overall survival at discharge or transfer to the referring hospital was 88.8%. Successful wean off ECMO occurred in 68 patients (94.4%) after a median of 90.5 hours (63.4-136.11). ECMO support was withdrawn in 4 patients (5.6%). CONCLUSIONS: The Avalon® dual-lumen veno-venous cannula can be used for respiratory ECMO in the neonatal population. However, as the incidence of right atrial perforation is not negligible, we suspended its used in this group of patients.

A 30 year perspective of the quality of evidence published in 25 clinical journals: signs of change?

METHODS: The quality of clinical studies published in five different specialties, over three decades was evaluated. Computerised search of the Medline database was undertaken to evaluate the articles published in 25 clinical journals in 1983, 1993, and 2003 from five different specialties (medicine, surgery, paediatrics, anaesthesia, and psychiatry). The number of randomised controlled trials (RCTs), meta-analyses, and other clinical trials (non-RCT) were noted. RESULTS: From the 27,030 articles evaluated, there were 2283 (8.4%) RCTs, 166 (0.6%) meta-analyses, and 4153 (15.4%) other clinical trials. For the proportion of RCTs, the rank order of the specialties was; anaesthesia (503; 18%), psychiatry (294; 9.6%), medicine (899; 8.1%), paediatrics (326; 6.4%), and surgery (261; 5.3%) (p<0.001). For the proportion of meta-analysis, the rank order of the specialties was; psychiatry (36; 1.2%), medicine (105; 0.9%), paediatrics (15; 0.3%), anaesthesia (6; 0.2%), and surgery (4; 0.1%) (p<0.001). Overall, from 1983 to 2003, there were increases in the proportion of RCTs (449, 5.9% to 1027, 9.6%), meta-analysis (0, 0% to 127, 1.2%), and other clinical trials (897, 12% to 1983, 19%) (p<0.001). This trend was apparent in each clinical specialty (p<0.001). CONCLUSIONS: Over the three decades evaluated, clinical trials, notably RCTs and meta-analysis form only a small proportion of articles published in prominent journals from five clinical specialties. This is notwithstanding the modest increases in the proportions of RCTs and meta-analysis over the same period.

Postsynaptic expression of tetanus toxin light chain blocks synaptogenesis in Drosophila.

During the development of the nervous system embryonic neurons are incorporated into neural networks that underlie behaviour. For example, during embryogenesis in Drosophila, motor neurons in every body segment are wired into the circuitry that drives the simple peristaltic locomotion of the larva. Very little is known about the way in which the necessary central synapses are formed in such a network or how their properties are controlled. One possibility is that presynaptic and postsynaptic elements form relatively independently of each other. Alternatively, there might be an interaction between presynaptic and postsynaptic neurons that allows for adjustment and plasticity in the embryonic network. Here we have addressed this issue by analysing the role of synaptic transmission in the formation of synaptic inputs onto identified motorneurons as the locomotor circuitry is assembled in the Drosophila embryo. We targeted the expression of tetanus toxin light chain (TeTxLC) to single identified neurons using the GAL4 system. TeTxLC prevents the evoked release of neurotransmitter by enzymatically cleaving the synaptic-vesicle-associated protein neuronal-Synaptobrevin (n-Syb) [1]. Unexpectedly, we found that the cells that expressed TeTxLC, which were themselves incapable of evoked release, showed a dramatic reduction in synaptic input. We detected this reduction both electrophysiologically and ultrastructurally.

The relative efficiency of cryogens used for plunge-cooling biological specimens.

Coolants used for freezing biological specimens were tested for cooling performance in the continuous plunge mode. Results from bare thermocouples showed that ethane cooled faster than propane or a propane:pentane mixture, even when warmed to 25 K above its freezing point. Propane coolants were more efficient than Freon 22 and the slowest cooling occurred in boiling liquid nitrogen. Hydrated gelatin specimens showed similar results with ethane cooling about 33% faster than propane. Epoxy resin specimens cooled faster than hydrated gelatin specimens of similar size. Hydrated and resin specimens cooled over increasing distances as plunge velocity increased. A bare thermocouple, however, cooled over a constant distance when plunged above a critical velocity. This phenomenon may reflect vapour formation and its suppression at high plunge velocities. The rate of cooling in hydrated specimens is shown to have an absolute limit and cannot be modelled by bare thermocouples or resin specimens.