A randomised crossover trial of closed loop automated oxygen control in preterm, ventilated infants.

AIM: To determine whether closed loop automated oxygen control resulted in a reduction in the duration and severity of desaturation episodes and the number of blood gases and chest radiographs in preterm, ventilated infants. METHODS: Infants were studied on two consecutive days for 12 hours on each day. They were randomised to receive standard care (standard period) or standard care with a closed loop automated oxygen control system (automated oxygen control period) first. RESULTS: Twenty-four infants with a median gestational age of 25.7 (range 23.1-32.6) weeks were studied at a median postconceptional age of 27.4 (range 24.3-34.9) weeks. During the automated oxygen control period, there were fewer desaturations that lasted >30 seconds (P = .032) or >60 seconds (P = .002), infants spent a higher proportion of the time within their target SpO2 range during the automated oxygen control period (P < .001), and fewer manual adjustments were made to the inspired oxygen concentration (mean 0.58 vs mean 11.29) (P < .001). There were no significant differences in the number of blood gases (P = .872) or chest radiographs (P = .366) between the two periods. CONCLUSION: Closed loop automated oxygen delivery resulted in fewer prolonged desaturations with more time spent in the targeted oxygen range.

Pathophysiological dissociation of the interaction between time pressure and trait anxiety during spatial orientation judgments.

Spatial orientation is achieved by integrating visual, vestibular and proprioceptive cues. Individuals that rely strongly upon visual cues to facilitate spatial orientation are termed visually dependent. Heightened visual reliance commonly occurs in patients following vestibular dysfunction and can influence clinical outcome. Additionally, psychological factors, including anxiety, are associated with poorer clinical outcome following vestibular dysfunction. Given that visual dependency measures are affected by psychological and contextual influences, such as time pressure, we investigated the interaction between time pressure and anxiety upon visual dependency in healthy controls and vestibular migraine patients. Visual dependency was assessed using a "Rod and Disk" task at baseline and under time pressure (3 s to complete the task). Non-situational (trait) and situational (state) anxiety levels were quantified using the Spielberg State-Trait Anxiety Inventory. We calculated the change in visual dependency (VD) [∆VD = VDtime pressure  - VDbaseline ] and correlated it with participants' trait anxiety scores. We observed a significant negative correlation between trait anxiety and the change in VD (R2  = .393, p < .001) in healthy controls and a positive correlation in dizzy patients (R2  = .317, p < .001). That is, healthy individuals that were more anxious became less visually dependent under time pressure (i.e., more accurate), whereas less anxious individuals became more visually dependent. The reverse was observed in vestibular migraine patients. Our results illustrate that anxiety can differentially modulate task performance during spatial orientation judgements under time pressure in healthy individuals and dizzy patients. These findings have potential implications for individualised patient rehabilitation therapies.

Abnormal visuo-vestibular interactions in vestibular migraine: a cross sectional study.

Vestibular migraine is among the commonest causes of episodic vertigo. Chronically, patients with vestibular migraine develop abnormal responsiveness to both vestibular and visual stimuli characterized by heightened self-motion sensitivity and visually-induced dizziness. Yet, the neural mechanisms mediating such symptoms remain unknown. We postulate that such symptoms are attributable to impaired visuo-vestibular cortical interactions, which in turn disrupts normal vestibular function. To assess this, we investigated whether prolonged, full-field visual motion exposure, which has been previously shown to modulate visual cortical excitability in both healthy individuals and avestibular patients, could disrupt vestibular ocular reflex and vestibular-perceptual thresholds of self-motion during rotations. Our findings reveal that vestibular migraine patients exhibited abnormally elevated reflexive and perceptual vestibular thresholds at baseline. Following visual motion exposure, both reflex and perceptual thresholds were significantly further increased in vestibular migraine patients relative to healthy controls, migraineurs without vestibular symptoms and patients with episodic vertigo due to a peripheral inner-ear disorder. Our results provide support for the notion of altered visuo-vestibular cortical interactions in vestibular migraine, as evidenced by vestibular threshold elevation following visual motion exposure.

Vestibulo-cortical hemispheric dominance: The link between anxiety and the vestibular system?

Vestibular processing and anxiety networks are functionally intertwined, as demonstrated by reports of reciprocal influences upon each other. Yet whether there is an underlying link between these two systems remains unknown. Previous findings have highlighted the involvement of hemispheric lateralisation in processing of both anxiety and vestibular signals. Accordingly, we explored the interaction between vestibular cortical processing and anxiety by assessing the relationship between anxiety levels and the degree of hemispheric lateralisation of vestibulo-cortical processing in 64 right-handed, healthy individuals. Vestibulo-cortical hemispheric lateralisation was determined by gaging the degree of caloric-induced nystagmus suppression following modulation of cortical excitability using trans-cranial direct current stimulation targeted over the posterior parietal cortex, an area implicated in the processing of vestibular signals. The degree of nystagmus suppression yields an objective biomarker, allowing the quantification of the degree of right vestibulo-cortical hemisphere dominance. Anxiety levels were quantified using the Trait component of the Spielberger State-Trait Anxiety Questionnaire. Our findings demonstrate that the degree of an individual's vestibulo-cortical hemispheric dominance correlates with their anxiety levels. That is, those individuals with greater right hemispheric vestibulo-cortical dominance exhibited lower levels of anxiety. By extension, our results support the notion that hemispheric lateralisation determines an individual's emotional processing, thereby linking cortical circuits involved in processing anxiety and vestibular signals, respectively.

Universal newborn hearing screening in South Africa: a single-centre study.

Hearing screening for newborn babies is an established protocol in many high-income countries. Implementing such screening has yielded significant socioeconomic advantages at both an individual and societal level. This has yet to permeate low/middle-income countries (LMIC). Here, we illustrate how newborn hearing screening needs to be contextually adapted for effective utilisation and implementation in an LMIC. Specifically, this advocates the use of auditory brainstem testing as the first-line approach. We propose that such adaptation serves to maximise clinical efficacy and community participation at a reduced cost.

Prospective assessment of a critical appraisal teaching programme on medical students' confidence and performance in appraising medical literature.

BACKGROUND: Previous research has demonstrated that medical students have insufficient knowledge of critical appraisal, a fundamental aspect of evidence-based medicine. We aimed to enhance medical students' critical appraisal skills using an innovative mixed-methods programme. METHODS: We designed a 2-day, mixed-methods, national teaching programme, including an interactive lecture and workshop, quiz and viva-style examination. Course efficacy was assessed using pre- and post-course confidence questionnaires and a quiz adapted from the validated Berlin Questionnaire. Data were analysed primarily using Wilcoxon Signed Ranks test. RESULTS: Fifty-nine participants from 17 medical schools completed the programme. Pre- and post-course scores demonstrated significant improvement in confidence (median score 5 vs 8; p < 0.001) and quiz performance (median score 9 vs 13; p < 0.001). CONCLUSION: Our study demonstrates the efficacy of a novel mixed-methods programme in teaching medical students about critical appraisal. Implementation of our approach within the undergraduate curriculum should enhance the uptake of these fundamental skills.

Interhemispheric control of sensory cue integration and self-motion perception.

Spatial orientation necessitates the integration of visual and vestibular sensory cues, in-turn facilitating self-motion perception. However, the neural mechanisms underpinning sensory integration remain unknown. Recently we have illustrated that spatial orientation and vestibular thresholds are influenced by interhemispheric asymmetries associated with the posterior parietal cortices (PPC) that predominantly house the vestibulo-cortical network. Given that sensory integration is a prerequisite to both spatial orientation and motion perception, we hypothesized that sensory integration is similarly subject to interhemispheric influences. Accordingly, we explored the relationship between vestibulo-cortical dominance - assessed using a biomarker, the degree of vestibular-nystagmus suppression following transcranial direct current stimulation over the PPC - with visual dependence measures obtained during performance of a sensory integration task (the rod-and-disk task). We observed that the degree of visual dependence was correlated with vestibulo-cortical dominance. Specifically, individuals with greater right hemispheric vestibulo-cortical dominance had reduced visual dependence. We proceeded to assess the significance of such dominance on behavior by correlating measures of visual dependence with self-motion perception in healthy subjects. We observed that right-handed individuals experienced illusionary self-motion (vection) quicker than left-handers and that the degree of vestibular cortical dominance was correlated with the time taken to experience vection, only during conditions that induced interhemispheric conflict. To conclude, we demonstrate that interhemispheric asymmetries associated with vestibulo-cortical processing in the PPC functionally and mechanistically link sensory integration and self-motion perception, facilitating spatial orientation. Our findings highlight the importance of dynamic interhemispheric competition upon control of vestibular behavior in humans.