Measurement and solutions to thermal comfort, CO2 and ventilation rates in schools

An Australian research facility, conducted a study on several different school classrooms in regards to their thermal comfort, CO2 levels, air temperature stratification and ventilation rates in a selection of Victorian (Melbourne, Australia) schools during a winter season. A brief literature review reveals similar IAQ problems elsewhere (outside Australia) and suggests several HVAC concepts that provide potential solutions. Our intention is to highlight particular IAQ discrepancies in existing school classroom design resulting from these case study measurements, suggesting construction and mechanical operational conditioning improvements.In particular this research confirms the urgency and necessity of addressing IAQ problems in schools, world wide. Our results of the Australian school classroom measurements are similar to other parts of the world, indicating that CO2 levels, ventilation rates and air temperatures are non-compliant with the standards.

The functional significance of ventilation frequency, and its relationship to oxygen demand in the resting brown long-eared bat, Plecotus auritus

Mean oxygen consumption and simultaneous ventilation frequency of nine non-reproductive brown long-eared bats (body mass 8.53–13.33 g) were measured on 159 occasions. Ambient (chamber) temperature at which the measurements were made ranged from 10.8 to 41.1°C. Apneic ventilation occurred in 22 of the 59 measurements made when mean oxygen consumption was less than 0.5 ml·min-1. No records of apneic ventilation were obtained when it was over 0.5 ml·min-1. The relationship between ventilation frequency and mean oxygen consumption depended on whether ventilation was apneic or non-apneic. When ventilation was non-apneic the relationship was positive and log-linear. When ventilation was apneic the relationship was log-log. Within the thermoneutral zone ventilation frequency was not significantly different from that predicted from allometric equations for a terrestrial mammal of equivalent body mass, but was significantly greater than that predicted for a bird. A reduction in the amount of oxygen consumed per breath occurred at ambient temperatures above the upper critical temperature (39°C).

Protocol-directed sedation versus non-protocol-directed sedation to reduce duration of mechanical ventilation in mechanically ventilated intensive care patients (review)

Background : The sedation needs of critically ill patients have been recognized as a core component of critical care and meeting these is vital to assist recovery and ensure humane treatment. There is growing evidence to suggest that sedation requirements are not always optimally managed. Sub-optimal sedation incorporates both under- and over-sedation and has been linked to both short-term (e.g. length of stay) and long-term (e.g. psychological recovery) outcomes. Various strategies have been proposed to improve sedation management and address aspects of assessment as well as delivery of sedation.

Objectives : To assess the effects of protocol-directed sedation management on the duration of mechanical ventilation and other relevant patient outcomes in mechanically ventilated intensive care unit (ICU) patients. We looked at various outcomes and examined the role of bias in order to examine the level of evidence for this intervention.

Search methods : We searched the Cochrane Central Register of Controlled trials (CENTRAL) (2013; Issue 11), MEDLINE (OvidSP) (1990 to November 2013), EMBASE (OvidSP) (1990 to November 2013), CINAHL (BIREME host) (1990 to November 2013), Database of Abstracts of Reviews of Effects (DARE) (1990 to November 2013), LILACS (1990 to November 2013), Current Controlled Trials and US National Institutes of Health Clinical Research Studies (1990 to November 2013), and reference lists of articles. We re-ran the search in October 2014. We will deal with any studies of interest when we update the review.

Selection criteria : We included randomized controlled trials (RCTs) conducted in adult ICUs comparing management with and without protocol-directed sedation.

Data collection and analysis : Two authors screened the titles and abstracts and then the full-text reports identified from our electronic search. We assessed seven domains of potential risk of bias for the included studies. We examined the clinical, methodological and statistical heterogeneity and used the random-effects model for meta-analysis where we considered it appropriate. We calculated the mean difference (MD) for duration of mechanical ventilation and risk ratio (RR) for mortality across studies, with 95% confidence intervals (CI).

Main results : We identified two eligible studies with 633 participants. Both included studies compared the use of protocol-directed sedation, specifically protocols delivered by nurses, with usual care. We rated the risk of selection bias due to random sequence generation low for one study and unclear for one study. The risk of selection bias related to allocation concealment was low for both studies. We also assessed detection and attrition bias as low for both studies while we considered performance bias high due to the inability to blind participants and clinicians in both studies. Risk due to other sources of bias, such as potential for contamination between groups and reporting bias, was considered unclear. There was no clear evidence of differences in duration of mechanical ventilation (MD -5.74 hours, 95% CI -62.01 to 50.53, low quality evidence), ICU length of stay (MD -0.62 days, 95% CI -2.97 to 1.73) and hospital length of stay (MD -3.78 days, 95% CI -8.54 to 0.97) between people being managed with protocol-directed sedation versus usual care. Similarly, there was no clear evidence of difference in hospital mortality between the two groups (RR 0.96, 95% CI 0.71 to 1.31, low quality evidence). ICU mortality was only reported in one study preventing pooling of data. There was no clear evidence of difference in the incidence of tracheostomy (RR 0.77, 95% CI 0.31 to 1.89). The studies reported few adverse event outcomes; one study reported self extubation while the other study reported re-intubation; given this difference in outcomes, pooling of data was not possible. There was significant heterogeneity between studies for duration of mechanical ventilation (I2 = 86%, P value = 0.008), ICU length of stay (I2 = 82%, P value = 0.02) and incidence of tracheostomy (I2 = 76%, P value = 0.04), with one study finding a reduction in duration of mechanical ventilation and incidence of tracheostomy and the other study finding no difference.

Authors' conclusions : There is currently insufficient evidence to evaluate the effectiveness of protocol-directed sedation. Results from the two RCTs were conflicting, resulting in the quality of the body of evidence as a whole being assessed as low. Further studies, taking into account contextual and clinician characteristics in different ICU environments, are necessary to inform future practice. Methodological strategies to reduce the risk of bias need to be considered in future studies.

Sedation protocols to reduce duration of mechanical ventilation in the ICU: a Cochrane Systematic Review

AIMS: Assess the effects of protocol-directed sedation management on the duration of mechanical ventilation and other relevant patient outcomes in mechanically ventilated intensive care unit patients. BACKGROUND: Sedation is a core component of critical care. Sub-optimal sedation management incorporates both under- and over-sedation and has been linked to poorer patient outcomes. DESIGN: Cochrane systematic review of randomized controlled trials. DATA SOURCES: Cochrane Central Register of Controlled trials, MEDLINE, EMBASE, CINAHL, Database of Abstracts of Reviews of Effects, LILACS, Current Controlled Trials and US National Institutes of Health Clinical Research Studies (1990-November 2013) and reference lists of articles were used. REVIEW METHODS: Randomized controlled trials conducted in intensive care units comparing management with and without protocol-directed sedation were included. Two authors screened titles, abstracts and full-text reports. Potential risk of bias was assessed. Clinical, methodological and statistical heterogeneity were examined and the random-effects model used for meta-analysis where appropriate. Mean difference for duration of mechanical ventilation and risk ratio for mortality, with 95% confidence intervals, were calculated. RESULTS: Two eligible studies with 633 participants comparing protocol-directed sedation delivered by nurses vs. usual care were identified. There was no evidence of differences in duration of mechanical ventilation or hospital mortality. There was statistically significant heterogeneity between studies for duration of mechanical ventilation. CONCLUSIONS: There is insufficient evidence to evaluate the effectiveness of protocol-directed sedation as results from the two randomized controlled trials were conflicting.

Emerging technologies in building envelopes

Advancements in engineering and space technology are increasingly finding application in buildings. Building envelopes are utilising components of high-technological solutions resulting in better visibility, greater light transmission, increased energy generation and storage capacity, improved shading and ventilation and integration with the external environment. This report summarises several technological advancements and suggests forthcoming directions for building envelope design. Many of the technologies presented here have been invented and developed in Australia, yet are not commonly used by the building construction industry.

Simulation of condensation problems in a roller-skating centre

A commercial roller-skating centre in southern Australia had condensation problems on both the roof and floor. The building is a typical warehouse-type structure with a high level of natural ventilation due to poor construction and permanently open vents. A computer model of the building, using the thermal simulation software TRNSYS, was calibrated from a sensitivity analysis of three key parameters, namely air exchange rate, roof surface heat transfer coefficient and deep ground temperature. The predicted times of condensation on the roof were compared with site observations. The time of year was predicted with acceptable accuracy, although earlier in the morning than had been observed. The effect of installing foil insulation in the roof was simulated. Under normal winter conditions, this modification was enough to stop the condensation. However, in unusually cold and humid conditions, condensation still occurred on both surfaces. This was overcome by heating the floor (15 W/m 2 ) for approximately eight hours. Subsequent modifications have demonstrated the value of the simulations.

Building T, Deakin University

Building T at Deakin University, Burwood in Victoria was designed by DesignInc. The development, located in Melbourne's eastern suburbs, utilises thermal mass and hybrid ventilation systems. This case study provides a detailed evaluation of the building in terms of its energy efficient design features.

Operating experiences with an advanced fabric energy storage system in Australia

Despite their proven track record in the cold climate countries of northern Europe, there are no reports in the research literature of experiences using advanced fabric energy storage (FES) systems in countries where cooling rather than heating is the main priority. This paper reports some of the experiences with the first known advanced FES system in Australia made over the first full calendar .year of operation. It is located in a three storey building on a university campus in Victoria and has been in operation since mid-2002. Temperature, energy use and operational mode data were recorded during 2003. Airflow measurements through the FES have been made in five areas of the building. On-going operating problems still exist with the system and this has prevented a conclusive evaluation of its suitability for the southern Australian climate.

Best practice in stabilisation of oral endotracheal tubes : a systematic review

Mechanical ventilation of patients in intensive care units is common practice. Artificial airways are utilised to facilitate ventilation and the endotracheal tube (ETT) is most commonly used for this purpose. The ETT must be stabilised to optimise ventilation and avoid displacement or unplanned extubation. Tube movement is a major factor in causing airway trauma. A destabilised tube can cause fatal complications. A systematic review was conducted to identify and analyse the best available evidence on ETT stabilisation to determine which stabilisation method resulted in reduced tube displacement and the least amount of unplanned or accidental extubations. The types of stabilisations included one or a combination of the following methods: twill or cotton tape, adhesive tape, gauze, or a manufactured device. All relevant randomised controlled and quasi-experimental studies of ETT stabilisation practices, identified through electronic and hand searching, were assessed for inclusion in the study. One published randomised controlled trial and six published quasi-experimental studies met the inclusion and exclusion criteria and were retrieved. Data were extracted independently by two reviewers. Results of the systematic review showed that no single method of ETT stabilisation could be identified as superior for minimising tube displacement and unplanned or accidental extubations. Rigorous randomised controlled trials with clearly identified and described ETT stabilisation methods are required to establish best practice. In addition, comparative research to evaluate cost effectiveness and nursing time requirements would also be of significant benefit to critical care nursing practice.