Benefit of a Visual Aid in the Management of Moderate-Severity Contrast Media Reactions.

OBJECTIVE: The purpose of this study was to compare management of moderate-severity reactions with and without a visual aid or flowchart in contrast medium reaction simulations. SUBJECTS AND METHODS: All attending radiologists and trainees were requested to participate in a contrast medium reaction simulation program, including a moderate-severity reaction scenario, and were randomized to groups having or not having a visual aid. The time to administer intramuscular (IM) epinephrine via automated injector and errors in administration were recorded. After the simulation, all participants completed a survey assessing their comfort in treating reactions to contrast media with and without a visual aid. RESULTS: A total of 138 participants were divided into 21 sessions in the program, with 68 participants in the moderate-severity reaction scenario. Eleven groups were provided a visual aid; 10 groups were not. Errors in management occurred in 18.2% (2 of 11) of groups with visual aids versus 40% (4 of 10) in groups without (p = 0.35), with epinephrine self-administration reflecting the most common error. Excluding the groups with errors, the mean time to administration of IM epinephrine was 97 seconds with versus 152 seconds without the visual aid (p = 0.04). Of the 138 participants, 97.8% agreed that the poster would aid in medication administration, and 87% agreed that it would help decrease time to administer medications. CONCLUSION: A visual aid increased the subjective confidence of radiologists in the dose and route of medication administration in the contrast medium reaction simulation and led to faster administration of epinephrine. Self-administration IM epinephrine errors were common and seen in both groups.

Location of glycine mutations within a bacterial collagen protein affects degree of disruption of triple-helix folding and conformation.

The hereditary bone disorder osteogenesis imperfecta is often caused by missense mutations in type I collagen that change one Gly residue to a larger residue and that break the typical (Gly-Xaa-Yaa)(n) sequence pattern. Site-directed mutagenesis in a recombinant bacterial collagen system was used to explore the effects of the Gly mutation position and of the identity of the residue replacing Gly in a homogeneous collagen molecular population. Homotrimeric bacterial collagen proteins with a Gly-to-Arg or Gly-to-Ser replacement formed stable triple-helix molecules with a reproducible 2 °C decrease in stability. All Gly replacements led to a significant delay in triple-helix folding, but a more dramatic delay was observed when the mutation was located near the N terminus of the triple-helix domain. This highly disruptive mutation, close to the globular N-terminal trimerization domain where folding is initiated, is likely to interfere with triple-helix nucleation. A positional effect of mutations was also suggested by trypsin sensitivity for a Gly-to-Arg replacement close to the triple-helix N terminus but not for the same replacement near the center of the molecule. The significant impact of the location of a mutation on triple-helix folding and conformation could relate to the severe consequences of mutations located near the C terminus of type I and type III collagens, where trimerization occurs and triple-helix folding is initiated.