Trainability of Cricoid Pressure Force Application: A Simulation-Based Study.

BACKGROUND: Aspiration of gastric contents is a leading cause of airway management-related mortality during anesthesia practice. Cricoid pressure (CP) is widely used during rapid sequence induction to prevent aspiration. National guidelines for CP suggest a target force of 10 N before and 30 N after loss of consciousness. However, few studies have rigorously assessed whether clinicians can be trained to consistently achieve these levels of force. We hypothesized that clinicians can be trained effectively to deliver 10-30 N during application of CP. METHODS: Clinicians (attending anesthesiologist, anesthesiology residents, certified registered nurse anesthetists, or operating room nurses) applied CP on a Vernier force plate simulator with measurements taken at 4 time points over 60 seconds, 2 measurements before and 2 measurements after loss of consciousness. A successful cycle required all 4 time points to be within the target range (10 ± 5 and 30 ± 5 N, respectively). After baseline assessment (n = 100 clinicians), a subset of 40 participants volunteered for education on recommended force targets, underwent self-regulated practice, and then performed 30 1-minute cycles of high-frequency simulation analyzed by cumulative sum analysis to assess their change in performance. RESULTS: At baseline, 5 cycles (1.3% [confidence interval {CI}, 0.3%-2.50%]) out of 400 were successful. Performance improved after education and self-regulated practice (16% successful cycles [CI, 7.8%-25%]), and performance during the last 4 of 30 cycles was 45% (CI, 33%-58%). The odds of success increased over time (odds ratio, 1.1; P < .001). By cumulative sum analysis, however, no subject crossed the h0 line, indicating that no one achieved proficiency of the predefined target forces. CONCLUSIONS: At baseline, performance was poor at achieving target forces specified by national guidelines. Simulation-based training improved the success rate, but no participant achieved the predefined threshold for proficiency.

Locomotor characteristics of the ground-walking chameleon Brookesia superciliaris.

Understanding the locomotor characteristics of early diverging ground-walking chameleons (members of the genera Brookesia, Rhampholeon, Palleon, and Rieppeleon) can help to explain how their unique morphology is adapted to fit their environment and mode of life. However, nearly all quantitative studies of chameleon locomotion thus far have focused on the larger "true arboreal" chameleons. We investigated kinematics and spatiotemporal gait characteristics of the Brown Leaf Chameleon (Brookesia superciliaris) on different substrates and compared them with true arboreal chameleons, nonchameleon lizards, and other small arboreal animals. Brookesia exhibits a combination of locomotor traits, some of which are traditionally arboreal, others more terrestrial, and a few that are very unusual. Like other chameleons, Brookesia moved more slowly on narrow dowels than on broad planks (simulating arboreal and terrestrial substrates, respectively), and its speed was primarily regulated by stride frequency rather than stride length. While Brookesia exhibits the traditionally arboreal trait of a high degree of humeral protraction at the beginning of stance, unlike most arboreal tetrapods, it uses smaller shoulder and hip excursions on narrower substrates, possibly reflecting its more terrestrial habits. When moving at very slow speeds, Brookesia often adopts an unusual footfall pattern, lateral-sequence lateral-couplets. Because Brookesia is a member of one of the earliest-diverging groups of chameleons, its locomotion may provide a good model for an intermediate stage in the evolution of arboreal chameleons. Thus, the transition to a fully arboreal way of life in "true arboreal" chameleons may have involved changes in spatiotemporal and kinematic characteristics as well as morphology.