Cranial Ontogeny in Stegoceras validum (Dinosauria: Pachycephalosauria): A Quantitative Model of Pachycephalosaur Dome Growth and Variation

Historically, studies of pachycephalosaurs have recognized plesiomorphically flat-headed taxa and apomorphically domed taxa. More recently, it has been suggested that the expression of the frontoparietal dome is ontogenetic and derived from a flat-headed juvenile morphology. However, strong evidence to support this hypothesis has been lacking. Here we test this hypothesis in a large, stratigraphically constrained sample of specimens assigned to Stegoceras validum, the best known pachycephalosaur, using multiple independent lines of evidence including conserved morphology of ornamentation, landmark-based allometric analyses of frontoparietal shape, and cranial bone histology. New specimens show that the diagnostic ornamentation of the parietosquamosal bar is conserved throughout the size range of the sample, which links flat-headed specimens to domed S. validum. High-resolution CT scans of three frontoparietals reveal that vascularity decreases with size and document a pattern that is consistent with previously proposed histological changes during growth. Furthermore, aspects of dome shape and size are strongly correlated and indicative of ontogenetic growth. These results are complementary and strongly support the hypothesis that the sample represents a growth series of a single taxon. Cranial dome growth is positively allometric, proceeds from a flat-headed to a domed state, and confirms the synonymy of Ornatotholus browni as a juvenile Stegoceras. This dataset serves as the first detailed model of growth and variation in a pachycephalosaur. Flat-headed juveniles possess three characters (externally open cranial sutures, tuberculate dorsal surface texture, and open supratemporal fenestrae) that are reduced or eliminated during ontogeny. These characters also occur in putative flat-headed taxa, suggesting that they may also represent juveniles of domed taxa. However, open cranial sutures and supratemporal fenestrae are plesiomorphic within Ornithischia, and thus should be expected in the adult stage of a primitive pachycephalosaur. Additional lines of evidence will be needed to resolve the taxonomic validity of flat-headed pachycephalosaur taxa

Out-of-Hospital Surgical Airway Management: Does Scope of Practice Equal Actual Practice?

Introduction: Pennsylvania, among other states, includes surgical airway management, or cricothyrotomy, within the paramedic scope of practice. However, there is scant literature that evaluates paramedic perception of clinical competency in cricothyrotomy. The goal of this project is to assess clinical exposure, education and self-perceived competency of ground paramedics in cricothyrotomy. Methods: Eighty-six paramedics employed by four ground emergency medical services agencies completed a 22-question written survey that assessed surgical airway attempts, training, skills verification, and perceptions about procedural competency. Descriptive statistics were used to evaluate responses. Results: Only 20% (17/86, 95% CI [11-28%]) of paramedics had attempted cricothyrotomy, most (13/17 or 76%, 95% CI [53-90%]) of whom had greater than 10 years experience. Most subjects (63/86 or 73%, 95% CI [64-82%]) did not reply that they are well-trained to perform cricothyrotomy and less than half (34/86 or 40%, 95% CI [30-50%]) felt they could correctly perform cricothyrotomy on their first attempt. Among subjects with five or more years of experience, 39/70 (56%, 95% CI [44-68%]) reported 0-1 hours per year of practical cricothyrotomy training within the last five years. Half of the subjects who were able to recall (40/80, 50% 95% CI [39-61%]) reported having proficiency verification for cricothyrotomy within the past five years. Conclusion: Paramedics surveyed indicated that cricothyrotomy is rarely performed, even among those with years of experience. Many paramedics felt that their training in this area is inadequate and did not feel confident to perform the procedure. Further study to determine whether to modify paramedic scope of practice and/or to develop improved educational and testing methods is warranted

Out-of-Hospital Surgical Airway Management: Does Scope of Practice Equal Actual Practice?

Introduction: Pennsylvania, among other states, includes surgical airway management, or cricothyrotomy, within the paramedic scope of practice. However, there is scant literature that evaluates paramedic perception of clinical competency in cricothyrotomy. The goal of this project is to assess clinical exposure, education and self-perceived competency of ground paramedics in cricothyrotomy.Methods: Eighty-six paramedics employed by four ground emergency medical services agencies completed a 22-question written survey that assessed surgical airway attempts, training, skills verification, and perceptions about procedural competency. Descriptive statistics were used to evaluate responses.Results: Only 20% (17/86, 95% CI [11-28%]) of paramedics had attempted cricothyrotomy, most (13/17 or 76%, 95% CI [53-90%]) of whom had greater than 10 years experience. Most subjects (63/86 or 73%, 95% CI [64-82%]) did not reply that they are well-trained to perform cricothyrotomy and less than half (34/86 or 40%, 95% CI [30-50%]) felt they could correctly perform cricothyrotomy on their first attempt. Among subjects with five or more years of experience, 39/70 (56%, 95% CI [44-68%]) reported 0-1 hours per year of practical cricothyrotomy training within the last five years. Half of the subjects who were able to recall (40/80, 50% 95% CI [39-61%]) reported having proficiency verification for cricothyrotomy within the past five years.Conclusion: Paramedics surveyed indicated that cricothyrotomy is rarely performed, even among those with years of experience. Many paramedics felt that their training in this area is inadequate and did not feel confident to perform the procedure. Further study to determine whether to modify paramedic scope of practice and/or to develop improved educational and testing methods is warranted