Implementing a peer-learning approach for the clinical education of respiratory therapy students.

INTRODUCTION: With recent clinical placement demands exceeding supply, the University Health Network (UHN) Respiratory Therapy (RT) department implemented a 2:1 student-to-preceptor model where a focus on peer learning (PL) becomes a key component of program success. PL can be defined as students learning from and with each other in both formal and informal ways. The shift towards facilitative student-directed models in other health care professions can be seen globally with the literature suggesting that 2:1 models not only support increases in student capacity but also improve the student learning experience through PL strategies. The aim of this study was to explore the perceptions of RT preceptors and students regarding the 2:1 model as an educational strategy in the context of their clinical experience. The study further explored experiences of PL to understand how learning is enabled in RT practice-based education, particularly within 2:1 models. METHODS: A qualitative descriptive study using single-episode semi-structured interviews with RT preceptors (n = 10) and students (n = 10) was conducted during the 2015-2016 RT student clinical year. Twelve open-ended interview questions were designed to draw out study participants' PL experiences and exploration of issues using a 2:1 model in the context of their clinical experience. Data were recorded, transcribed verbatim, and analyzed using thematic analysis. RESULTS: The content analysis resulted in two broad themes with respect to the RT 2:1 educational model: "enablers" and "barriers" to a PL approach. The 2:1 model was preferred by students and preceptors early on in the clinical training due to the benefits of PL, whereas opportunities to showcase independent practice was preferred towards the end of their clinical year. Furthermore, careful planning, resources, and supports need to be implemented to augment benefits and diminish potential disadvantages of using a 2:1 model structure. CONCLUSION: Participants felt that a 2:1 model strongly contributes to a supportive learning environment and can have a positive influence on the RT student clinical experience at UHN. Along with the improved critical thinking and student engagement opportunities that a 2:1 model offers, increased placement numbers are also supported.

The impact of topical mydriatic ophthalmic solutions on retinal vascular reactivity and blood flow.

The impact of mydriatic agents on the standardized provocation of retinal vascular reactivity has not been systematically investigated. Our aim was to investigate the effect of commonly used mydriatic agents on the provoked vascular response of retinal arterioles. One eye was randomly selected for mydriasis from 10 healthy volunteers (age 23.3 ± 4.9 years). A single drop of: 1% tropicamide (T), or a combination of 0.8% tropicamide and 5% phenylephrine (TP), or 1% cyclopentolate (C) were instilled into the volunteers lower fornix at each of three visits. Volunteers underwent a standardized isocapnic hyperoxic provocation. Four retinal hemodynamic measurements were acquired with the Canon Laser Blood Flowmeter at equivalent positions on the superior temporal arteriole (STA) and inferior temporal arteriole (ITA) at baseline, during provocation and after recovery. Statistical analysis was performed using linear mixed-effect models. Pre- and post-dilation measurements indicated that pupil diameter increased with use of T, TP, C (all <0.001), while systolic blood pressure, diastolic blood pressure and intraocular pressure did not change significantly (all >0.05). In response to a standardized isocapnic hyperoxic challenge, blood vessel diameter, blood velocity and flow decreased in both the STA and ITA relative to baseline. Comparison between the change elicited by isocapnic hyperoxic gas stimuli with respect to blood vessel diameter, blood velocity, blood flow, were equivalent for each mydriatic agent in the STA (p = 0.66, p = 0.99, p = 0.99, respectively) and the ITA (p = 0.85, p = 0.80, p = 0.66, respectively). Furthermore, comparison between the change in the STA and ITA with respect to the above parameters showed equivalent responses in both vessels for each mydriatic agent: T (p = 0.92, p = 0.99, p = 0.35; respectively), TP (p = 0.89, p = 0.96, p = 0.62; respectively), and C (p = 0.87, p = 0.35, p = 0.56; respectively). The provoked retinal vascular reactivity response to standardized isocapnic hyperoxia was equivalent irrespective of the agent used to achieve mydriasis.

Relative magnitude of vascular reactivity in the major arterioles of the retina.

The relative magnitude of vascular reactivity to inhaled gas stimuli in the major retinal arterioles has not been systematically investigated. The purpose of this study was to compare the magnitude of retinal vascular reactivity in response to inhaled gas provocation at equivalent measurement sites in the superior-, and inferior-, temporal retinal arterioles (STA, ITA). One randomly selected eye of each of 17 healthy volunteers (age 24.4 ± 4.7) was prospectively enrolled. Volunteers were connected to a sequential gas delivery circuit and a computer-controlled gas blender (RespirAct™, Thornhill Research Inc., Canada) and underwent an isocapnic hyperoxic challenge i.e. P(ET)O(2) of 500 mm Hg with P(ET)CO(2) maintained at 38 mm Hg during baseline and hyperoxia. Four retinal hemodynamic measurements were acquired using bi-directional laser Doppler velocimetry and simultaneous vessel densitometry (Canon Laser Blood Flowmeter, CLBF-100, Japan) at equivalent positions on the STA and ITA. Statistical analysis was performed using linear mixed-effect models. During the hyperoxic phase, the vessel diameter (STA p=0.004; ITA p=0.003), blood velocity (STA p<0.001; ITA p<0.001) and flow (STA p<0.001; ITA p<0.001) decreased in both the STA and the ITA relative to baseline. The diameter, velocity and flow were equivalent between STA and ITA at baseline and during hyperoxia; and their magnitude of change remained comparable with hyperoxia (p>0.05). The magnitude of retinal arteriolar vascular reactivity in response to isocapnic hyperoxic inhaled gas challenge was not significantly different between the STA and ITA. However, the correlation analysis did not reveal a significant relationship between the percentage changes in diameter, velocity and flow of the STA and ITA and did not demonstrate equal responses from the STA and ITA to gas provocation.

Noninvasive MRI measures of microstructural and cerebrovascular changes during normal swine brain development.

The swine brain is emerging as a potentially valuable translational animal model of neurodevelopment and offers the ability to assess the impact of experimentally induced neurological disorders. The goal for this study was to characterize swine brain development using noninvasive MRI measures of microstructural and cerebrovascular changes. Thirteen pigs at various postnatal ages (2.3-43.5 kg) were imaged on a 1.5-Tesla MRI system. Microstructural changes were assessed using diffusion tensor imaging measures of mean diffusivity and fractional anisotropy. Cerebrovascular changes were assessed using arterial spin labeling measures of baseline cerebral blood flow (CBF) and the cerebrovascular reactivity (CVR) of the blood-oxygen level dependent (BOLD) MRI signal to CO2. We found a positive logarithmic relationship for regional tissue volumes and fractional anisotropy with body weight, which is similar to the pattern reported in the developing human brain. Unlike in the maturing human brain, no consistent changes in mean diffusivity or baseline CBF with development were observed. Changes in BOLD CVR exhibited a positive logarithmic relationship with body weight, which may impact the interpretation of functional MRI results at different stages of development. This animal model can be validated by applying the same noninvasive measures in humans.

Feasibility and precision of cerebral blood flow and cerebrovascular reactivity MRI measurements using a computer-controlled gas delivery system in an anesthetised juvenile animal model.

PURPOSE: To demonstrate the feasibility and repeatability of cerebrovascular reactivity (CVR) imaging using a controlled CO(2) challenge in mechanically ventilated juvenile pigs. MATERIALS AND METHODS: Precise end-tidal partial pressure CO(2) (PETCO(2)) control was achieved via a computer-controlled model-driven prospective end-tidal targeting (MPET) system integrated with mechanical ventilation using a custom-built secondary breathing circuit. Test-retest blood-oxygen level dependent (BOLD) CVR images were collected in nine juvenile pigs by quantifying the BOLD response to iso-oxic square-wave PETCO(2) changes. For comparison, test-retest baseline arterial spin labeling (ASL) cerebral blood flow (CBF) images were collected. Repeatability was quantified using the intra-class correlation coefficient (ICC) and coefficient of variation (CV). RESULTS: The repeatability of the PETCO(2) (CV < 2%) step changes resulted in BOLD CVR ICC > 0.94 and CV < 6% for cortical brain regions, which was similar to ASL CBF repeatability (ICC > 0.96 and CV < 4%). CONCLUSION: This study demonstrates the feasibility and precision of CVR imaging with an MPET CO(2) challenge in mechanically ventilated subjects using an animal model. Translation of this method into clinical imaging protocols may enable CVR imaging in young children with cerebrovascular disease who require general anesthesia.