Learning in Pediatric Emergency Situations: A Qualitative Study of Residents' Perspectives.

OBJECTIVES: To explore resident learning in the context of emergency situations. The guiding research questions were: How do residents learn in emergency situations? What factors facilitate or hinder their learning? DESIGN: A qualitative approach was used in order to understand the different perspectives of participants and explore the context of emergency situations. Aware of the complex sociocultural interactions in emergency situations, we used the methodology of constructivist grounded theory. SETTING: A medium-sized pediatric academic hospital in San Antonio, TX. SUBJECTS: Twenty pediatric residents participated in semi-structured interviews. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We used an iterative process of data collection and analysis. The process continued until thematic saturation was reached. The data were coded and analyzed using constant comparison. Codes were clustered into themes informed by the theory of situated learning. Several methods were used to ensure trustworthiness of results. Three main themes were identified. First, resident participation in emergency situations takes different forms. Residents participate mostly in helping roles. Watching is an under-recognized form of participation yet offered unique experiences. Managing roles are rarely afforded to residents. Second, resident participation is informed by the context of the emergency situation. Based on contextual clues (e.g., safety, needs), residents infer potential risks and values from their participation, which guides their participatory role. Residents may shift their form of participation, based on changes in the context. Supervisors play a significant role in guiding resident participation. Third, engagement, a state of cognitive and emotional focus, is critical in learning. The context of the emergency situation plays a role in the level of resident engagement. Supervisors may also foster resident engagement. CONCLUSIONS: Resident participation in emergency situations is complex and informed by the context. Learning in emergency situations is influenced by residents' level of mental engagement. Supervisors may positively guide resident participation, foster engagement, and enable them to reach their learning goals in emergency situations.

ICAM-1 mediates surface contact between neutrophils and keratocytes following corneal epithelial abrasion in the mouse.

Corneal epithelial abrasion elicits an inflammatory response involving neutrophil (PMN) recruitment from the limbal vessels into the corneal stroma. These migrating PMNs make surface contact with collagen and stromal keratocytes. Using mice deficient in PMN integrin CD18, we previously showed that PMN contact with stromal keratocytes is CD18-dependent, while contact with collagen is CD18-independent. In the present study, we wished to extend these observations and determine if ICAM-1, a known ligand for CD18, mediates PMN contact with keratocytes during corneal wound healing. Uninjured and injured right corneas from C57Bl/6 wild type (WT) mice and ICAM-1(-/-) mice were processed for transmission electron microscopy and imaged for morphometric analysis. PMN migration, stromal thickness, and ICAM-1 staining were evaluated using light microscopy. Twelve hours after epithelial abrasion, PMN surface contact with paralimbal keratocytes in ICAM-1(-/-) corneas was reduced to  Ëœ 50% of that observed in WT corneas; PMN surface contact with collagen was not affected. Stromal thickness (edema), keratocyte network surface area and keratocyte shape were similar in ICAM-1(-/-) and WT corneas. WT keratocyte ICAM-1 expression was detected at baseline and ICAM-1 staining intensity increased following injury. Since ICAM-1 is readily detected on mouse keratocytes and PMN-keratocyte surface contact in ICAM-1(-/-) mice is markedly reduced, the data suggest PMN adhesive interactions with keratocyte-stromal networks is in part regulated by keratocyte ICAM-1 expression.

Neutrophil interactions with keratocytes during corneal epithelial wound healing: a role for CD18 integrins.

PURPOSE: To determine the role of keratocytes and leukocyte beta(2) (CD18) integrins in neutrophil (PMN) migration through the corneal stroma after epithelial scrape injury. METHODS: Using C57BL/6 wild-type and CD18(-/-) mice, corneas were excised at 6 hours (wild-type) or 24 hours (CD18(-/-)) after central corneal epithelial abrasion, time points determined previously to have similar levels of emigrated PMNs. Corneas were prepared for ultrastructural morphometric analysis of PMNs, keratocyte networks, and collagen. RESULTS: Transmission electron microscopy revealed intact keratocyte networks within the paralimbus that were morphometrically similar, regardless of epithelial injury or mouse genotype. Secondary to epithelial abrasion, extravasated PMNs within the paralimbus developed close contacts with keratocytes and collagen. In wild-type mice, 40% of the PMN surface was in contact with the keratocyte surface, and this value decreased to 10% in CD18(-/-) mice. PMN contact with collagen was similar in wild-type and CD18(-/-) mice, with approximately 50% of the PMN surface contacting the collagen fibrils. Since corneal edema resulting from scrape injury was similar, regardless of genotype and did not involve structural changes in collagen fibrils, these data favor a direct role for CD18 in mediating PMN contact with keratocytes. CONCLUSIONS: The data show that in response to epithelial scrape injury, PMN migration in the corneal stroma involves close contact between keratocytes and collagen. Although PMN-keratocyte contacts require CD18 integrins, contact with collagen is CD18 independent. Fundamentally, PMN migration along keratocyte networks constitutes the beginning of a new experimental concept for understanding leukocyte migration within the wounded cornea.