Clinical and molecular epidemiological features of critically ill patients with invasive group A Streptococcus infections: a Belgian multicenter case-series.

peer reviewed[en] BACKGROUND: Recent alerts have highlighted an increase in group A streptococcal (GAS) infections since 2022 in Europe and the United States. Streptococcus pyogenes can cause limited skin or mucosal disease, but can also present as severe invasive disease necessitating critical care. We performed a multicenter retrospective study of patients with GAS infections recently admitted to Belgian intensive care units (ICUs) since January 2022. We describe patient characteristics and investigate the molecular epidemiology of the S. pyogenes strains involved. RESULTS: Between January 2022 and May 2023, a total of 86 cases (56 adults, 30 children) with GAS disease were admitted to critical care in the university hospitals of Leuven, Antwerp and Liège. We noted a strikingly high incidence of severe community-acquired pneumonia (sCAP) (45% of adults, 77% of children) complicated with empyema in 45% and 83% of adult and pediatric cases, respectively. Two-thirds of patients with S. pyogenes pneumonia had viral co-infection, with influenza (13 adults, 5 children) predominating. Other disease presentations included necrotizing fasciitis (23% of adults), other severe skin/soft tissue infections (16% of adults, 13% of children) and ear/nose/throat infections (13% of adults, 13% of children). Cardiogenic shock was frequent (36% of adults, 20% of children). Fifty-six patients (65%) had toxic shock syndrome. Organ support requirements were high and included invasive mechanical ventilation (77% of adults, 50% of children), renal replacement therapy (29% of adults, 3% of children) and extracorporeal membrane oxygenation (20% of adults, 7% of children). Mortality was 21% in adults and 3% in children. Genomic analysis of S. pyogenes strains from 55 out of 86 patients showed a predominance of emm1 strains (73%), with a replacement of the M1global lineage by the toxigenic M1UK lineage (83% of emm1 strains were M1UK). CONCLUSIONS: The recent rise of severe GAS infections (2022-23) is associated with introduction of the M1UK lineage in Belgium, but other factors may be at play-including intense circulation of respiratory viruses and potentially an immune debt after the COVID pandemic. Importantly, critical care physicians should include S. pyogenes as causative pathogen in the differential diagnosis of sCAP

Experimental Two-Port Characterization of the Aeroacoustic Transmission Properties of a Truck’s Exhaust System

Maximizing the acoustic attenuation is one of the important design criteria of automotive exhaust systems. Although both analytical and numerical approaches exist to evaluate the acoustic transmission properties of exhaust systems, they are, at present, insufficient to model the full geometrical complexity and to accurately assess the influence of thermal and aerodynamic phenomena onto the acoustic attenuation characteristics. For this reason, an experimental test campaign is often still indispensable to evaluate the aeroacoustic performance of exhaust systems. One of the most commonly used experimental characterization techniques for flow duct systems is the two-port characterization. Although this measurement approach is limited to low frequencies, below the traversal cut-on frequency of the inlet and outlet ducts, it allows making an in-depth analysis of the acoustic transmission properties of duct systems, including flow and thermal effects with an arbitrary geometrical complexity. Furthermore, using a two-port characterization allows combining various duct elements, which are measured and/or modeled independently from each other, in a network approach, enabling a straightforward acoustic evaluation of various flow-duct system design alternatives. In this paper, an experimental two-port determination technique is used to assess the influence of aerodynamic effects on the acoustic transmission properties of a part of a truck’s exhaust system, containing four different components: an inlet bent duct; a flexible, corrugated, connection pipe; a complex muffler configuration; and a tailpipe. The experimental methodology is based on a multiple microphone calibration technique to determine the various environmental parameters. In this way, the final accuracy is increased and the need of accurate instrumental assessment of these parameters is avoided. The aeroacoustic performance of the various flow duct elements is determined and analyzed for each component and the use of a network approach, combining the various subcomponents is evaluated. It is shown that an experimental two-port characterization technique provides useful insight in the noise attenuation principles of flow duct systems and is ideally suited to be adopted in a network approach.status: publishe

Near-Infrared-Based Cerebral Oximetry for Prediction of Severe Acute Kidney Injury in Critically Ill Children After Cardiac Surgery.

Cerebral oximetry by near-infrared spectroscopy is used frequently in critically ill children but guidelines on its use for decision making in the PICU are lacking. We investigated cerebral near-infrared spectroscopy oximetry in its ability to predict severe acute kidney injury after pediatric cardiac surgery and assessed its additional predictive value to routinely collected data. Design: Prospective observational study. The cerebral oximeter was blinded to clinicians. Setting: Twelve-bed tertiary PICU, University Hospitals Leuven, Belgium, between October 2012 and November 2015. Patients: Critically ill children with congenital heart disease, younger than 12 years old, were monitored with cerebral near-infrared spectroscopy oximetry from PICU admission until they were successfully weaned off mechanical ventilation. Interventions: None. Measurements and Main Results: The primary outcome was prediction of severe acute kidney injury 6 hours before its occurrence during the first week of intensive care. Near-infrared spectroscopy-derived predictors and routinely collected clinical data were compared and combined to assess added predictive value. Of the 156 children included in the analysis, 55 (35%) developed severe acute kidney injury. The most discriminant near-infrared spectroscopy-derived predictor was near-infrared spectroscopy variability (area under the receiver operating characteristic curve, 0.68; 95% CI, 0.67-0.68), but was outperformed by a clinical model including baseline serum creatinine, cyanotic cardiopathy pre-surgery, blood pressure, and heart frequency (area under the receiver operating characteristic curve, 0.75; 95% CI, 0.75-0.75; p < 0.001). Combining clinical and near-infrared spectroscopy information improved model performance (area under the receiver operating characteristic curve, 0.79; 95% CI, 0.79-0.80; p < 0.001). Conclusions: After pediatric cardiac surgery, near-infrared spectroscopy variability combined with clinical information improved discrimination for acute kidney injury. Future studies are required to identify whether supplementary, timely clinical interventions at the bedside, based on near-infrared spectroscopy variability analysis, could improve outcome.status: Published onlin

The value of the FORE-SIGHT (TM) monitor in the postoperative phase after congenital cardiac surgery. A descriptive statistical interim-analysis

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An Analysis of Reliability and Accuracy of Muscle Thickness Ultrasonography in Critically Ill Children and Adults

Background: Muscle wasting starts already within the first week in critically patients and is strongly related to poor outcome. Nevertheless, the early detection of muscle wasting is difficult. Therefore, we investigated the reliability and accuracy of ultrasonography to evaluate skeletal muscle wasting in critically ill children and adults. Methods: This prospective observational study enrolled 30 sedated critically ill children and 14 critically ill adults. Two independent investigators made 210 ultrasonographical assessments of muscle thigh thickness. Inter- and intraobserver reliability and cutoff levels were calculated as a function of muscle thickness and the expected reduction in muscle size (predefined at 20% and 30%). Results: Mean ± SD muscle thickness was 1.67 ± 0.55 cm in the pediatric and 2.10 ± 0.85 cm in the adult population. The median absolute interobserver variability was 0.07 cm (interquartile range [IQR], 0.04-0.20 cm) in the pediatric population and 0.05 cm (IQR, 0.03-0.09 cm) in the adult population. However, the absolute intraobserver accuracy had a 95% confidence interval of 0.43 cm in children and 0.22 cm in adults. Only a 30% decrease (0.50 cm) in muscle thickness can be detected in critically ill children. Conclusion: Although the interobserver variability is acceptable in the pediatric population, the intraobserver variability is too large with respect to the expected reduction in muscle thickness. In adults, ultrasonography may be a reliable tool for early detection of muscle mass wasting.status: publishe

Effect of Tight Glucose Control with Insulin on the Thyroid Axis of Critically Ill Children and Its Relation with Outcome

Context:Tight glucose control (TGC) to normal-for-age fasting blood glucose levels reduced morbidity and mortality in surgical adult and pediatric intensive care unit (ICU) patients. In adults, TGC did not affect the illness-induced alterations in thyroid hormones. With better feeding in children than in adult patients, we hypothesized that TGC in pediatric ICU patients reactivates the thyroid axis.Objective:The aim of this study was to assess the impact of TGC on the thyroid axis in pediatric ICU patients and to investigate how these changes affect the TGC outcome benefit.Design and Patients:We conducted a preplanned analysis of all patients not treated with thyroid hormone, dopamine, or corticosteroids who were included in a randomized controlled trial on TGC (n = 700).Main Outcome Measures:Serum TSH, T(4), T(3), and rT(3) were measured upon admission and on ICU day 3 or the last ICU day for patients discharged earlier. Changes from baseline were compared for the TGC and usual care groups. The impact on the outcome benefit of TGC was assessed with multivariable Cox proportional hazard analysis, correcting for baseline risk factors.Results:TGC further lowered the T(3)/rT(3) ratio (P = 0.03), whereas TSH (P = 0.09) and T(4) (P = 0.3) were unaltered. With TGC, the likelihood of earlier live discharge from the ICU was 19% higher at any time (hazard ratio, 1.190; 95% confidence interval, 1.010-1.407; P = 0.03). This benefit was statistically explained by the further reduction of T(3)/rT(3) with TGC because an increase in T(3)/rT(3) was strongly associated with a lower likelihood for earlier live discharge (hazard ratio per unit increase, 0.863; 95% confidence interval, 0.806-0.927; P <0.0001).Conclusions:TGC further accentuated the peripheral inactivation of thyroid hormone. This effect, mimicking a fasting response, statistically explained part of the clinical outcome benefit of TGC.status: publishe