Mid-infrared spectroscopy as a potential tool for reconstructing lake salinity

Many aquatic ecosystems in Australia are impacted or threatened by salinisation; however, there is a paucity of records detailing the changes in salinity of individual water bodies that extend beyond a few decades. One way to overcome this issue is the use of inference models, which have typically been based on biological proxies. This pilot project investigates the potential for mid-infrared spectroscopy (MIRS) to provide an alternative method of reconstructing past salinity levels in Australian lakes. A small (19 lakes) calibration dataset was used to develop a MIRS-based lake water salinity inference model (measured vs. inferred salinity, based on leave-one-out cross-validation, R2 = 0.64). This model and a previously published diatom–salinity model were both used to infer salinity levels in Tower Hill Lake in south-eastern Australia, over the last 60 years. Comparisons between these reconstructions and measured salinity data from Tower Hill Lake indicate that salinities inferred by the MIRS model more closely resembled the measured values than those produced using the diatom model, predominantly in terms of the actual values inferred, but also with regard to the trends observed. This supports the hypothesis that MIRS can provide a valuable new tool for reconstructing lake salinity.Laura Cunningham, John Tibby, Sean Forrester, Cameron Barr and Jan Skjemsta

A tool for routine monitoring and feedback of morbidities following paediatric cardiac surgery

Short-term survival after paediatric cardiac surgery has improved significantly over the past 20 years and increasing attention is being given to measuring and reducing incidence of morbidities following surgery. How to best use routinely collected data to share morbidity information constitutes a challenge for clinical teams interested in analysing their outcomes for quality improvement. We aimed to develop a tool facilitating this process in the context of monitoring morbidities following paediatric cardiac surgery, as part of a prospective multi-centre research study in the United Kingdom. We developed a prototype software tool to analyse and present data about morbidities associated with cardiac surgery in children. We used an iterative process, involving engagement with potential users, tool design and implementation, and feedback collection. Graphical data displays were based on the use of icons and graphs designed in collaboration with clinicians. Our tool enables automatic creation of graphical summaries, displayed as a Microsoft PowerPoint presentation, from a spreadsheet containing patient-level data about specified cardiac surgery morbidities. Data summaries include numbers/percentages of cases with morbidities reported, co-occurrences of different morbidities, and time series of each complication over a time window. Our work was characterised by a very high level of interaction with potential users of the tool, enabling us to promptly account for feedback and suggestions from clinicians and data managers. The United Kingdom centres involved in the project received the tool positively, and several expressed their interest in using it as part of their routine practice

Evaluating the Impact of Cardiopulmonary Bypass Priming Fluids on Bleeding After Pediatric Cardiac Surgery:A Systematic Review and Meta-Analysis

OBJECTIVES: Cardiopulmonary bypass (CPB) predisposes young children to coagulopathy. The authors evaluated possible effects of CPB priming fluids on perioperative bleeding in pediatric cardiac surgery.DESIGN: Meta-analysis and systematic review of previously published studies.SETTING: Each study was conducted in a surgical center or intensive care unit.PARTICIPANTS: Studies investigating patients &lt;18 years without underlying hematologic disorders were included.INTERVENTIONS: The authors evaluated randomized controlled trials (RCTs) published between 1980 and 2020 on MEDLINE, EMBASE, PubMed, and CENTRAL databases. The primary outcome was postoperative bleeding; secondary endpoints included blood product transfusion, mortality, and safety.MEASUREMENTS AND MAIN RESULTS: Twenty eligible RCTs were analyzed, with a total of 1,550 patients and a median of 66 patients per study (range 20-200). The most frequently assessed intervention was adding fresh frozen plasma (FFP) to the prime (8/20), followed by albumin (5/20), artificial colloids (5/20), and blood-based priming solutions (3/20). Ten studies with 771 patients evaluated blood loss at 24 hours in mL/kg and were included in a meta-analysis. Most of them investigated the addition of FFP to the priming fluid (7/10). No significant difference was found between intervention and control groups, with a mean difference of -0.13 (-2.61 to 2.34), p = 0.92, I2 = 69%. Further study endpoints were described but their reporting was too heterogeneous to be quantitatively analyzed.CONCLUSIONS: This systematic review of current evidence did not show an effect of different CPB priming solutions on 24-hour blood loss. The analysis was limited by heterogeneity within the dataset regarding population, type of intervention, dosing, and the chosen comparator, compromising any conclusions.</p

Improving Risk Adjustment for Mortality After Pediatric Cardiac Surgery: The UK PRAiS2 Model

BACKGROUND: Partial Risk Adjustment in Surgery (PRAiS), a risk model for 30-day mortality after children's heart surgery, has been used by the UK National Congenital Heart Disease Audit to report expected risk-adjusted survival since 2013. This study aimed to improve the model by incorporating additional comorbidity and diagnostic information. METHODS: The model development dataset was all procedures performed between 2009 and 2014 in all UK and Ireland congenital cardiac centers. The outcome measure was death within each 30-day surgical episode. Model development followed an iterative process of clinical discussion and development and assessment of models using logistic regression under 25 × 5 cross-validation. Performance was measured using Akaike information criterion, the area under the receiver-operating characteristic curve (AUC), and calibration. The final model was assessed in an external 2014 to 2015 validation dataset. RESULTS: The development dataset comprised 21,838 30-day surgical episodes, with 539 deaths (mortality, 2.5%). The validation dataset comprised 4,207 episodes, with 97 deaths (mortality, 2.3%). The updated risk model included 15 procedural, 11 diagnostic, and 4 comorbidity groupings, and nonlinear functions of age and weight. Performance under cross-validation was: median AUC of 0.83 (range, 0.82 to 0.83), median calibration slope and intercept of 0.92 (range, 0.64 to 1.25) and -0.23 (range, -1.08 to 0.85) respectively. In the validation dataset, the AUC was 0.86 (95% confidence interval [CI], 0.82 to 0.89), and the calibration slope and intercept were 1.01 (95% CI, 0.83 to 1.18) and 0.11 (95% CI, -0.45 to 0.67), respectively, showing excellent performance. CONCLUSIONS: A more sophisticated PRAiS2 risk model for UK use was developed with additional comorbidity and diagnostic information, alongside age and weight as nonlinear variables

Validation of the Brief Developmental Assessment in pre-school children with heart disease

INTRODUCTION: The objective of this study was to prospectively validate the “Brief Developmental Assessment”, which is a new early recognition tool for neurodevelopmental abnormalities in children with heart disease that was developed for use by cardiac teams. METHODS: This was a prospective validation study among a representative sample of 960 pre-school children with heart disease from three United Kingdom tertiary cardiac centres who were analysed grouped into five separate age bands. RESULTS: The “Brief Developmental Assessment” was successfully validated in the older four age bands, but not in the youngest representing infants under the age of 4 months, as pre-set validation thresholds were met – lower 95% confidence limit for the correlation coefficient above 0.75 – in terms of agreement of scores between two raters and with an external measure the “Mullen Scales of Early Learning”. On the basis of American Association of Pediatrics Guidelines, which state that the sensitivity and specificity of a developmental screening tool should fall between 70 and 80%, “Brief Developmental Assessment” outcome of Red meets this threshold for detection of Mullen scores >2 standard deviations below the mean. CONCLUSION: The “Brief Developmental Assessment” may be used to improve the quality of assessment of children with heart disease. This will require a training package for users and a guide to action for abnormal results. Further research is needed to determine how best to deploy the “Brief Developmental Assessment” at different time points in children with heart disease and to determine the management strategy in infants younger than 4 months old

Accuracy of enteral syringes with commonly prescribed paediatric liquid medicines

OBJECTIVE: Oral syringes are the preferred method for delivering paediatric enteral drugs; however, little is known about factors affecting accuracy, particularly at volumes <5 mL. We investigated volumetric accuracy for enteral syringes, using commercially available liquid drug formulations with various physicochemical properties at clinically relevant volumes. DESIGN: In vitro experiment. INTERVENTIONS: Ten drugs were tested using two syringe brands (Baxa, Medicina) across a range of formulation volumes (0.05-5 mL) and syringe sizes (1-5 mL). Syringe weights (empty and filled) were converted into volume, using known formulation densities. Ten replications were performed for each drug/syringe/volume combination. MAIN OUTCOME MEASURES: Delivered volume accuracy was expressed as a percentage of intended volume, with the desired range being within ±10%. RESULTS: Baxa demonstrated a slight positive bias (excess average volumes delivered) at the smallest volumes for each syringe size, while Medicina had poorer precision (greater variability, analysis of variance-interactions all p<0.005). From these results, we identified the limit for volume accuracy for each syringe size and brand. Of note, the 1 mL syringe for both brands was inaccurate for delivering volumes ≤0.1 mL. The physicochemical properties of pH (range 2.82-7.45), surface tension (30.2-86.7 mN/m) and viscosity (2-299 mPaS) did not influence error in a discernible pattern. CONCLUSIONS: Dosing was inaccurate when small volumes were used across all syringe sizes and brands. These reflect volumes used in clinical practice. Administration error could potentially be reduced by (1) clinicians using syringes appropriate to dosing volumes and (2) manufacturers revising formulation concentrations for drugs

Evaluation of PMIP2 and PMIP3 simulations of mid-Holocene climate in the Indo-Pacific, Australasian and Southern Ocean regions

This study uses the simplified patterns of temperature and effective precipitation approach from the Australian component of the international palaeoclimate synthesis effort (INTegration of Ice core, MArine and TErrestrial records - OZ-INTIMATE) to compare atmosphere–ocean general circulation model (AOGCM) simulations and proxy reconstructions. The approach is used in order to identify important properties (e.g. circulation and precipitation) of past climatic states from the models and proxies, which is a primary objective of the Southern Hemisphere Assessment of PalaeoEnvironment (SHAPE) initiative. The AOGCM data are taken from the Paleoclimate Modelling Intercomparison Project (PMIP) mid-Holocene (ca. 6000 years before present, 6 ka) and pre-industrial control (ca. 1750 CE, 0 ka) experiments. The synthesis presented here shows that the models and proxies agree on the differences in climate state for 6 ka relative to 0 ka, when they are insolation driven. The largest uncertainty between the models and the proxies occurs over the Indo-Pacific Warm Pool (IPWP). The analysis shows that the lower temperatures in the Pacific at around 6 ka in the models may be the result of an enhancement of an existing systematic error. It is therefore difficult to decipher which one of the proxies and/or the models is correct. This study also shows that a reduction in the Equator-to-pole temperature difference in the Southern Hemisphere causes the mid-latitude westerly wind strength to reduce in the models; however, the simulated rainfall actually increases over the southern temperate zone of Australia as a result of higher convective precipitation. Such a mechanism (increased convection) may be useful for resolving disparities between different regional proxy records and model simulations. Finally, after assessing the available datasets (model and proxy), opportunities for better model–proxy integrated research are discussed.Duncan Ackerley, Jessica Reeves, Cameron Barr, Helen Bostock, Kathryn Fitzsimmons, Michael-Shawn Fletcher, Chris Gouramanis, Helen McGregor, Scott Mooney, Steven J. Phipps, John Tibby and Jonathan Tyle