Intermittent self-pulsing in a fiber raman laser

We report on an experimental study of intermittent self-pulsing caused by the coupling of the first and second Stokes cascades in a fiber Raman laser © 2012 OSA.

Rib-cage-movement measurements as a potential new trigger signal in non-invasive mechanical ventilation

Non-invasive ventilation performed through an oronasal mask is a standard in clinical and homecare mechanical ventilation. Besides all its advantages, inevitable leaks through the mask cause errors in the feedback information provided by the airflow sensor and, hence, patient-ventilator asynchrony with multiple negative consequences. Here we investigate a new way to provide a trigger to the ventilator. The method is based on the measurement of rib cage movement at the onset of inspiration and during breathing by fibre-optic sensors. In a series of simultaneous measurements by a long-period fibre grating sensor and pneumotachograph we provide the statistical evidence of the 200 ms lag of the pneumo with respect the fibre-optic signal. The lag is registered consistently across three independent delay metrics. Further, we discuss exceptions from this trend and identify the needed improvements to the proposed fibre-sensing scheme.

Infants' detection of synchrony between sounds and pauses in the movement of an object

The present study investigated the development of sensitivity to temporal synchrony between sounds of impact and pauses in the movement of an object by infants of 2 1/2, 4 and 6 months of age. Ninety infants were tested across four experiments with side-by-side videos of a red and white square and a blue and yellow triangle along with a centralized soundtrack which was synchronized with only one of the films. This preference phase was then followed by a search phase, where the two films were accompanied by intermittent bursts of the soundtrack from each object. Twomonth- olds showed no evidence of matching films and soundtracks on the basis of synchrony, however 4-month-olds looked more on the second block of trials to the object which paused when the sound occurred and directed more first looks during the preference phase to the matching object. Six-month-olds demonstrated significantly more first looks to the mismatched object during the search phase only. These results suggest that infants relate impact sounds with synchronous pauses in continuous motion by the age of four months.

Rôle du diaphragme au cours de l'expiration chez l'enfant sous ventilation mécanique

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Explaining intermittent exporting:exit and conditional re-entry in export markets

Intermittent exporting is something of a puzzle. In theory, exporting represents a major commitment, and is often the starting point for further internationalisation. However, intermittent exporters exit and subsequently re-enter exporting, sometimes frequently. We develop a conceptual model to explain how firm characteristics and market conditions interact to affect the decision to exit and re-enter exporting, and model this process using an extensive dataset of French manufacturing firms from 1997 to 2007. As anticipated, smaller and less productive firms are more likely to exit exporting, and react more strongly to changes in both domestic and foreign markets than larger firms. Exit and re-entry are closely linked. Firms with a low exit probability also have a high likelihood of re-entry, and vice versa. However, the way in which firms react to market conditions at the time of exit matters greatly in determining the likelihood of re-entry: thus re-entry depends crucially on the strategic rationale for exit. Our analysis helps explain the opportunistic and intermittent exporting of (mainly) small firms, the demand conditions under which intermittent exporting is most likely to occur, and the firm attributes most likely to give rise to such behavior.

Barriers to reporting child maltreatment: do emergency medical services professionals fully understand their role as mandatory reporters?

BACKGROUND: Child maltreatment is underreported in the United States and in North Carolina. In North Carolina and other states, mandatory reporting laws require various professionals to make reports, thereby helping to reduce underreporting of child maltreatment. This study aims to understand why emergency medical services (EMS) professionals may fail to report suspicions of maltreatment despite mandatory reporting policies. METHODS: A web-based, anonymous, voluntary survey of EMS professionals in North Carolina was used to assess knowledge of their agency's written protocols and potential reasons for underreporting suspicion of maltreatment (n=444). Results were based on descriptive statistics. Responses of line staff and leadership personnel were compared using chi-square analysis. RESULTS: Thirty-eight percent of respondents were unaware of their agency's written protocols regarding reporting of child maltreatment. Additionally, 25% of EMS professionals who knew of their agency's protocol incorrectly believed that the report should be filed by someone other than the person with firsthand knowledge of the suspected maltreatment. Leadership personnel generally understood reporting requirements better than did line staff. Respondents indicated that peers may fail to report maltreatment for several reasons: they believe another authority would file the report, including the hospital (52.3%) or law enforcement (27.7%); they are uncertain whether they had witnessed abuse (47.7%); and they are uncertain about what should be reported (41.4%). LIMITATIONS: This survey may not generalize to all EMS professionals in North Carolina. CONCLUSIONS: Training opportunities for EMS professionals that address proper identification and reporting of child maltreatment, as well as cross-agency information sharing, are warranted.

Rôle du diaphragme au cours de l'expiration chez l'enfant sous ventilation mécanique

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Synchronized and controlled release of metformin hydrochloride/glipizide from elementary osmotic delivery

The combination of metformin hydrochloride (MTF) and glipizide (GLZ) is second-line medication for diabetes mellitus type 2 (DMT2). In the present study, elementary osmotic pump(EOP)tablet is designed to deliver the combination of MTF and GLZ in a sustained and synchronized manner. By analyzing different variables of the formulation, sodium hydrogen carbonate is introduced as pH modifier to improve the release of GLZ, while ethyl cellulose acts as release retardant to reduce the burst release phase of MTF. A two factor, three level face-centered central composite design (FCCD) is applied to investigate the impact of different factors on drug release profile. Compared with conventional tablets, the elementary osmotic pump (EOP) tablet demonstrates a controlled release behavior with relative bioavailability of 99.2% for MTF and 99.3% for GLZ. Data also shows EOP tablet is able to release MTF and GLZ in a synchronized and sustained manner both in vitro and in vivo

Weaning from ventilation

Aims/purpose: Getting off the ventilator is an important patient-centred outcome for patients with acute respiratory failure. It signifies an improvement in patient condition, enables easier communication, reduces fear and anxiety and consequently a reduced requirement for sedatives. Weaning from ventilation therefore is a core ICU nursing task that is addressed in this presentation.
Presentation description: There are different schools of thought on when ventilator weaning begins including: (a) from intubation with titration of support; and (b) only when the patient’s condition improves. There are also different schools of thought on how to wean including gradual reductions in ventilator support to: (a) a low level consistent with extubation; or (b) to a level to attempt a spontaneous breathing trial followed by extubation if successful. Regardless of the approach, what is patient-relevant is the need to determine early when the patient may be ‘ready’ to discontinue ventilation. This time point can be assessed using simple criteria and should involve all ICU staff to the level of their experience. This presentation challenges the notion that only senior nurses or nurses with a ‘weaning course’ should be involved in the weaning process and proposes opportunities for engaging nurses with all levels of experience.
Conclusion: An ICU nursing taskforce that is focused and engaged in determining patient readiness for weaning can make a strong contribution to patient-relevant outcomes.

Protocolised weaning from mechanical ventilation: pairing a qualitative review with an effectiveness review

In our systematic review of protocolised weaning from mechanical ventilation (Blackwood 2014) we found significant heterogeneity that could not be explained by subgroup analysis (type of protocol, ICU). We suspected that factors unreported in the trials relating to context and mechanisms of using the weaning protocols contributed to the heterogeneity. Therefore we set out to conduct a Cochrane qualitative evidence-synthesis of ‘sibling studies’ (qualitative studies undertaken alongside the included trials that may have examined these factors) and ‘stand-alone’ qualitative studies reporting barriers and facilitators to successful implementation of weaning protocols. The qualitative review was novel, there were few templates or guidelines which challenged us to consider how best to synthesise and report this evidence. However, the benefits of conducting this review are that not only do we have a template for future qualitative syntheses for the ACE group, but specifically for trials of weaning protocols, we found context-specific evidence concerning if, how and why specific protocols have been effective in the settings in which they were delivered and received.

Evaluation of passive ventilation provision in domestic housing retrofit

Increasing energy efficiency in the residential sector, while maintaining adequate home ventilation for health and well-being, is proving to be a challenge. This study assesses the efficacy of passive ventilation strategies designed to comply with building regulations and imposed after housing energy-efficiency retrofits. In particular, it focuses on the provision of ventilation using background through-wall vents, which remains a common strategy in a number of European countries including Ireland and the UK, where vent sizes, related to floor area, are stipulated in building regulations. A collective of social housing, with background through-wall vents installed post thermal retrofit, is taken as a case study. These homes are modelled to interrogate the impact of the passive ventilation strategy on house air exchange rate and thermal heating energy loads. The reaction of occupants to through-wall vent installation is decidedly negative and many block vents to limit thermal discomfort and heat loss. Simulation studies show significant external air ingress through vents. A wide range of effective air change rates are observed when vents are sized without reference to building airtightness, and significant energy penalties result for the leakier homes. This study evaluates the provision of passive through-wall ventilation as part of a retrofit programme and shows it to have a number of drawbacks that may impact on the health of the building and its occupants and ultimately be at odds with the aims of achieving energy efficiency in the residential sector.

Compared with specialist registrars, experienced staff nurses shorten the duration of weaning neonates from mechanical ventilation

OBJECTIVE: To compare the overall performance of specially trained neonatal nurses acting autonomously, unsupervised, and without a protocol with specialist registrars when weaning neonates from mechanical ventilation.

DESIGN: Prospective, randomized, controlled trial.

SETTING: A single neonatal intensive care unit.

PATIENTS: Neonates requiring conventional mechanical ventilation (n = 50).

INTERVENTIONS: Infants on conventional ventilation were randomly assigned to receive either nurse-led (n = 25) or registrar-led (n = 23) weaning. A total of 48 infants completed the study (two infants in the registrar group were excluded when their parents withdrew consent).

MEASUREMENTS AND MAIN RESULTS: The main outcome measure, median weaning time, was 1200 mins (95% confidence interval [CI], 621-1779 mins) in the nurse group and 3015 mins (95% CI, 2650-3380 mins) in the registrar group (p = .0458). The median time from treatment assignment to the first ventilator change was 60 mins (95% CI, 52-68 mins) in the nurse group and 120 mins (95% CI, 103-137 mins) in the registrar group (p = .35). On average, the nurses made ventilator changes every 4.5 hrs (95% CI, 2.9-6 hrs) and the registrars every 7.2 hrs (95% CI, 5.4-9 hrs; p = .003). The median number (range) of backward steps taken per infant was 0 (0-5 steps) in the nurse group and 1 (0-5 steps) in the registrar group (p = .019).

CONCLUSIONS: The findings of this study suggest that additional domains of neonatal critical care could be reviewed for their potential transfer to appropriately prepared nurses.

Non-invasive Ventilation of Patients with ARDS: Insights from the LUNG SAFE Study

Background: Non-invasive ventilation (NIV) is increasingly used in patients with Acute Respiratory Distress Syndrome (ARDS). Whether, during NIV, the categorization of ARDS severity based on the PaO2/FiO2 Berlin criteria is useful is unknown. The evidence supporting NIV use in patients with ARDS remains relatively sparse.

Methods: The Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE (LUNG SAFE) study described the management of patients with ARDS. This sub-study examines the current practice of NIV use in ARDS, the utility of the PaO2/FiO2 ratio in classifying patients receiving NIV and the impact of NIV on outcome.

Results: Of 2,813 patients with ARDS, 436 (15.5%) were managed with NIV on days 1 and 2 following fulfillment of diagnostic criteria. Classification of ARDS severity based on PaO2/FiO2 ratio was associated with an increase in intensity of ventilatory support, NIV failure, and Intensive Care Unit (ICU) mortality. NIV failure occurred in 22.2% of mild, 42.3% of moderate and 47.1% of patients with severe ARDS. Hospital mortality in patients with NIV success and failure was 16.1 % and 45.4%, respectively. NIV use was independently associated with increased ICU (HR 1.446; [1.159-1.805]), but not hospital mortality. In a propensity matched analysis, ICU mortality was higher in NIV than invasively ventilated patients with a PaO2/FiO2 lower than 150 mmHg.

Conclusions: NIV was used in 15% of patients with ARDS, irrespective of severity category. NIV appears to be associated with higher ICU mortality in patients with a PaO2/FiO2 lower than 150 mmHg.

Trial Registration: ClinicalTrials.gov NCT02010073