Arterial Line Placement Pitfalls Can Be Demonstrated and Visualized With an Inexpensive, Wearable Trainer.

BACKGROUND: Radial arterial line placement is commonly performed in various clinical settings, including the emergency department. However, learners are successful on the first attempt only half of the time. Simulation can provide learners with procedure practice opportunities outside of clinical practice to increase confidence and chances of success. OBJECTIVES: We set out to build an arterial line trainer that would be inexpensive and reusable, wearable, anatomically realistic, and echogenic to allow for ultrasound use. We also hoped to devise a clear option that would allow for demonstration of procedure pitfalls. DISCUSSION: The arterial line trainer requires 4 hours of assembly time and costs $160. This includes enough material to make 48 tissue pads. The ballistics gel pad is echogenic; it can be customized with clear gel for direct anatomic visualization or dyed gel for more realism. The trainer also has a pulsatile artery for practice using anatomic landmarks. Visualization of the following important arterial line placement pitfalls is possible: suboptimal angle of approach, inadequate advancement of the catheter, and through-and-through vessel puncture. CONCLUSIONS: Our inexpensive trainer can help physicians and physicians in training conceptualize, practice, and troubleshoot the pitfalls of arterial line placement. Training programs looking to help learners understand the mechanics of arterial line placement may find it a useful tool.

Environmental and Biological Influences on Carbonate Precipitation Within Hot Spring Microbial Mats in Little Hot Creek, CA.

Microbial mats are found in a variety of modern environments, with evidence for their presence as old as the Archean. There is much debate about the rates and conditions of processes that eventually lithify and preserve mats as microbialites. Here, we apply novel tracer experiments to quantify both mat biomass addition and the formation of CaCO3. Microbial mats from Little Hot Creek (LHC), California, contain calcium carbonate that formed within multiple mat layers, and thus constitute a good test case to investigate the relationship between the rate of microbial mat growth and carbonate precipitation. The laminated LHC mats were divided into four layers via color and fabric, and waters within and above the mat were collected to determine their carbonate saturation states. Samples of the microbial mat were also collected for 16S rRNA analysis of microbial communities in each layer. Rates of carbonate precipitation and carbon fixation were measured in the laboratory by incubating homogenized samples from each mat layer with δ13C-labeled HCO3- for 24 h. Comparing these rates with those from experimental controls, poisoned with NaN3 and HgCl2, allowed for differences in biogenic and abiogenic precipitation to be determined. Carbon fixation rates were highest in the top layer of the mat (0.17% new organic carbon/day), which also contained the most phototrophs. Isotope-labeled carbonate was precipitated in all four layers of living and poisoned mat samples. In the top layer, the precipitation rate in living mat samples was negligible although abiotic precipitation occurred. In contrast, the bottom three layers exhibited biologically enhanced carbonate precipitation. The lack of correlation between rates of carbon fixation and biogenic carbonate precipitation suggests that processes other than autotrophy may play more significant roles in the preservation of mats as microbialites.