Cross-Sectional Study Using Virtual Reality to Measure Cognition.

Dual-task research is limited in its transferability to authentic contexts because laboratory conditions do not replicate real-world physical activity and decision-making scenarios. Creating valid, reliable methodologies to assess physiological and behavioral responses under varying physical and cognitive demands using virtual reality (VR) environment addresses this limitation. This study determined the feasibility of using VR to investigate the effects of dual-tasking on healthy young adults' cognitive performance. Three dual-tasking conditions (i.e., standing, preferred-paced walking, and fast-paced walking, each with blocked congruent and incongruent tasks) were developed. Using a within-subjects, randomized design, thirty-two young adults (17 female, mean age = 21.03 ± 2.86) were randomly assigned to a starting condition but experienced all three conditions. Physiological responses of heart rate (HR) and accelerometry data measured energy expenditure as the physical demand. Behavioral responses of reaction time and error rate quantified cognitive performance. Results indicated that (a) each condition verified independent physiological and behavioral responses; (b) reaction time and error rate during preferred walking or fast-paced walking dual-tasking conditions was significantly lower than standing condition; and surprisingly, (c) congruent tasks showed lower reaction time than the incongruent tasks. These findings suggest that it is feasible to use VR to assess the effects of dual-task conditions. Specifically, walking can optimize the motor-cognitive dual-task performance, compared to standing. These findings may be attributed to the dose-response effects of exercise intensity. Future studies should incorporate advanced technology such as the VR exercise.

Simprovisation: A model for student-led simulation.

BACKGROUND: Simulation is well established in medical education, with scenarios designed by faculty members to elicit specific learning outcomes. We describe and evaluate a learner-led style of simulation-based education that puts learners in control of the day. Simprovisation harnesses the principles of socially constructed learning and andragogy, encouraging learners to address their own learning requirements. Participants are divided into two groups. They are asked to consider their learning needs and are provided with resources and faculty member support to write two simulation scenarios. Faculty members remain available to guide scenario writing and offer 'micro-teaching' on required topics. The groups then swap and participate in the scenarios written for them by the opposite group. Each scenario is followed by a structured debriefing, providing opportunities for participants to share their learning from the scenarios. Simprovisation harnesses the principles of socially constructed learning and andragogy, encouraging learners to address their own learning requirements METHODS: We delivered Simprovisation to 62 participants ranging from fourth-year medical students to junior doctors. We conducted pre- and post-course questionnaire surveys and invited participants to focus groups to discuss their experiences. RESULTS: Our feedback questionnaire shows 100% of 58 respondents found Simprovisation useful, and 95% were able to meet at least two out of three self-determined learning outcomes. Thematic analysis of focus group transcriptions showed that participants valued group-based work and setting their own learning objectives. They found writing simulation scenarios to be challenging, but a valuable source of learning, and reported being more engaged compared with previous simulation study days. CONCLUSIONS: Simprovisation is an innovative style of simulation-based education that allows learners to effectively define and address their own learning needs.

Cognitively Demanding Object Negotiation While Walking and Texting.

Cell phone related pedestrian injuries are increasing, but the underlying causes remain unclear. Here, we studied how cell phone use directly affected obstacle avoidance ability. Thirty healthy adults participated. Cognitive capacity was quantified using standard tests. Participants walked on a treadmill in a virtual reality environment with and without performing a texting-like cell phone task. Participants also navigated either 'no', 'simple' or 'complex' object negotiation tasks that directly manipulated the cognitive complexity of this object negotiation task. Cell phone use led to more collisions, delayed responses, and increased variability of responses when navigating objects. Mean object avoidance responses were further delayed for the cognitively more complex object negotiation task. Individuals' baseline attentional capacity inversely predicted the number of object collisions when participants used the cell phone. Individuals with higher cognitive flexibility (i.e., better ability to switch between tasks) performed better on the cell phone task when they had to negotiate obstacles. Importantly, cognitive ability predicted performance only when both tasks (texting and negotiating objects) were being performed. Thus, using a cell phone while walking introduces a visual distraction that impairs healthy adults' ability to respond to cognitively demanding object negotiation tasks in their environment.

Diagnosis and treatment of pheochromocytoma in an academic hospital from 1997 to 2007.

BACKGROUND: The diagnosis and treatment of pheochromocytoma pose a challenge to physicians. Several trends in the presentation, diagnosis, and surgical treatment of pheochromocytoma have emerged in the last 10 years. The diagnostic accuracy and consequences of misdiagnosis of pheochromocytoma are not well known. We aimed to systemically study the diagnostic accuracy and treatment outcomes of pheochromocytoma and to reveal the causes and consequences of misdiagnosis (including both overdiagnosis and underdiagnosis). METHODS: We reviewed the electronic and paper charts of 49 patients who underwent adrenalectomy or adrenal biopsy with either preoperative or pathologic diagnosis of pheochromocytoma in a large academic hospital from 1997 to 2007. Three groups of patients (overdiagnosed, correctly diagnosed, and underdiagnosed) were compared on clinical courses, biochemical tests, imaging studies, and surgical outcomes. RESULTS: Pheochromocytoma was overdiagnosed in 9 patients, correctly diagnosed in 30 patients, and underdiagnosed in 10 patients. The overdiagnosis rate was 23% (9/39), and the underdiagnosis rate was 25% (10/40). The 3 distinct groups of patients exhibited significant differences in clinical presentation, biochemical tests, and imaging characteristics. The most common causes of overdiagnosis were misinterpretation of borderline biochemical test results and overzealous imaging. Overdiagnosis subjected patients to unnecessary adrenalectomy and its complications. The most common cause of underdiagnosis was failure to consider and test for pheochromocytoma. Underdiagnosis resulted in dangerous adrenal biopsy or adrenalectomy with hypertensive crisis and nearly doubled the length of stay in hospital. Surgical resection of correctly diagnosed pheochromocytoma was largely effective and safe, but intraoperative and postoperative complications occurred in some patients. CONCLUSION: We conclude that misdiagnosis of pheochromocytoma is not uncommon and causes serious adverse effects. Correct interpretation of biochemical tests and imaging is crucial to a correct diagnosis, and pheochromocytoma should always be included in the differential diagnosis of any adrenal mass. Our data suggest that physician education is needed to improve the diagnosis and treatment of pheochromocytoma.

Micro-computed tomographic analysis of bone healing subsequent to graft placement.

A micro-computed tomographic (muCT) analysis of bone healing subsequent to graft (tri calcium phosphate/TCP) placement in the maxillary sinus prior to dental endosteal implant placement was the focus of the current study. Ten trephined rod shaped human bone cores were obtained three months after the placement of particulate graft material. Using the muCT, samples were evaluated at 6 and 20 mum resolutions. The images exhibited regions of different grey scale (GL) magnitudes for bone and graft allowing a differentiation and quantification of the two sample regions. The GL threshold magnitudes at 20 mum resolution were determined to be less than 235 for organic and fluid, 235-450 for bone, 400-600 for bone and graft, and 600 and above for the graft material. The graft material was integrated with the bone showing the osteoconductivity of the TCP material, the mean bone volume was 25.50 (11.28) ranging from 5.66 to 37.9 and the mean graft volume was 0.42 (0.37) ranging from 0.01 to 1.17. The mean graft to bone volume ratio was 0.015 (0.01) with a range from 0.002 to 0.024. The structural data and observations from two- and three-dimensional images provided a valuable assessment of the graft distribution, its relation to modeling bone and also the anatomy of the healing bone. Thus this study demonstrated the capability to uniquely evaluate the status of healing bone associated with this TCP grafting biomaterial with opportunities for subsequent correlations with histomorphometrical studies and clinical outcomes of these type implant treatments.

An evaluation of the "cut and push" method of percutaneous endoscopic gastrostomy (PEG) removal.

BACKGROUND: This study aimed to establish whether 15-Fr gauge percutaneous endoscopic gastrostomy (PEG) tubes can be safely removed by "cut and push." METHODS: Patients were prospectively recruited who were found to be without significant intestinal dysfunction requiring removal of Freka (Fresenius Kabi) 15-Fr gauge PEG tubes. The PEG tube was cut close to the stoma and the remnant pushed into the gastric lumen with a 14-Fr nasogastric tube. Patients were asked to observe their stool for the remnant. Patients were contacted at day 7 and an abdominal x-ray was arranged for those who had not seen the remnant in the stool. If the remnant was still present as seen on plain x-ray, the patient was contacted on day 14. A second x-ray was ordered if the patient reported that they had still not seen the remnant. Outcome measures were PEG remnant observed in stool or not seen on plain abdominal x-ray, and adverse events. RESULTS: Forty-two patients were recruited over 29 months: 38 head and neck patients and 4 others (stroke, head injury, cystic fibrosis [CF], and lung cancer). Of these, 41 had passed the remnant by day 8 and all by day 14. No adverse events occurred. CONCLUSIONS: We have concluded that cut and push is a safe method of removal for Freka 15-Fr PEG tubes in ambulant patients without significant gastrointestinal history.