Background Patients infected with severe acute respiratory syndrome coronavirus (SARS-CoV-2) can develop severe illness necessitating intensive care admission. Critically ill patients are susceptible for the development of secondary bacterial infections. Due to a combination of virus- and drug-induced immunosuppression, critically ill patients with corona virus disease 2019 (COVID-19) may even have a higher risk of developing a secondary infection. These secondary infections can aggravate the severity of illness and increase the risk of death. Further research on secondary infections in COVID-19 patients is essential. Therefore, the objective of this study was to investigate the incidence and associated risk factors of secondary bacterial infections and to identify the most common groups of pathogens in critically ill COVID-19 patients. Methods This mono-center, retrospective observational cohort study was performed at the intensive care unit (ICU) of the Jessa Hospital, Hasselt, Belgium. All adult COVID-19 patients admitted to the ICU from 13th March 2020 until 17th October 2020, were eligible for inclusion in the study. Data from the resulting 116 patients were prospectively entered into a customized database. The resulting database was retrospectively reviewed to investigate three types of secondary bacterial infections (secondary pneumonia, bloodstream infections of unknown origin, catheter-related sepsis). Results Of 94 included patients, 68% acquired at least one of the studied secondary bacterial infections during their ICU stay. Almost two thirds of patients (65.96%, n = 62) acquired a secondary pneumonia, whereas 29.79% (n = 28) acquired a bacteremia of unknown origin and a smaller proportion of patients (14.89%, n = 14) acquired a catheter-related sepsis. Male gender (P = 0.05), diabetes mellitus (P = 0.03) and the cumulative dose of corticosteroids (P = 0.004) were associated with increased risk of secondary bacterial infection. The most common pathogens detected in the cultures of patients with secondary pneumonia were Gram-negative bacilli. Bacteremia of unknown origin and catheter-related sepsis were mostly caused by Gram-positive cocci. Conclusion This study confirms that the incidence of secondary bacterial infections is very high in critically ill COVID-19 patients. These patients are at highest risk of developing secondary pneumonia. Male gender, a history of diabetes mellitus and the administration of corticosteroids were associated with increased risk of secondary bacterial infection.

Purpose of review-Critically ill patients usually develop hyperglycemia, which is associated with adverse outcome. Controversy exists whether the relationship is causal or not. This review summarizes recent evidence regarding glucose control in the intensive care unit. Recent findings-Despite promising effects of tight glucose control in pioneer randomized controlled trials, the benefit has not been confirmed in subsequent multicenter studies and one trial found potential harm. This discrepancy could be explained by methodological differences between the trials rather than by a different case mix. Strategies to improve the efficacy and safety of tight glucose control have been developed, including the use of computerized treatment algorithms. Summary-The ideal blood glucose target remains unclear and may depend on the context. As compared to tolerating severe hyperglycemia, tight glucose control is safe and effective in patients receiving early parenteral nutrition when provided with a protocol that includes frequent, accurate glucose measurements and avoids large glucose fluctuations. All patient subgroups potentially benefit, with the possible exception of patients with poorly controlled diabetes, who may need less aggressive glucose control. It remains unclear whether tight glucose control is beneficial or not in the absence of early parenteral nutrition.

Background: In critically ill children, omitting early use of parenteral nutrition (late-PN versus early-PN) reduced infections, accelerated weaning from mechanical ventilation, and shortened PICU stay. We hypothesized that fasting-induced ketogenesis mediates these benefits. Methods: In a secondary analysis of the PEPaNIC RCT (N = 1440), the impact of late-PN versus early-PN on plasma 3-hydroxybutyrate (3HB), and on blood glucose, plasma insulin, and glucagon as key ketogenesis regulators, was determined for 96 matched patients staying ≥ 5 days in PICU, and the day of maximal 3HB-effect, if any, was identified. Subsequently, in the total study population, plasma 3HB and late-PN-affected ketogenesis regulators were measured on that average day of maximal 3HB effect. Multivariable Cox proportional hazard and logistic regression analyses were performed adjusting for randomization and baseline risk factors. Whether any potential mediator role for 3HB was direct or indirect was assessed by further adjusting for ketogenesis regulators. Results: In the matched cohort (n = 96), late-PN versus early-PN increased plasma 3HB throughout PICU days 1-5 (P < 0.0001), maximally on PICU day 2. Also, blood glucose (P < 0.001) and plasma insulin (P < 0.0001), but not glucagon, were affected. In the total cohort (n = 1142 with available plasma), late-PN increased plasma 3HB on PICU day 2 (day 1 for shorter stayers) from (median [IQR]) 0.04 [0.04-0.04] mmol/L to 0.75 [0.04-2.03] mmol/L (P < 0.0001). The 3HB effect of late-PN statistically explained its impact on weaning from mechanical ventilation (P = 0.0002) and on time to live PICU discharge (P = 0.004). Further adjustment for regulators of ketogenesis did not alter these findings. Conclusion: Withholding early-PN in critically ill children significantly increased plasma 3HB, a direct effect that statistically mediated an important part of its outcome benefit.

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Background Recent evidence suggests a potentially protective effect of increasing ketone body availability via accepting low macronutrient intake early after onset of critical illness. The impact of blood glucose control with insulin on circulating ketones is unclear. Whereas lowering blood glucose may activate ketogenesis, high insulin concentrations may have the opposite effect. We hypothesized that the previously reported protective effects of tight glucose control in critically ill patients receiving early parenteral nutrition may have been mediated in part by activation of ketogenesis. Methods This is a secondary analysis of 3 randomized controlled trials on tight versus liberal blood glucose control in the intensive care unit, including 700 critically ill children and 2748 critically ill adults. All patients received early parenteral nutrition as part of the contemporary standard of care. Before studying a potential mediator role of circulating ketones in improving outcome, we performed a time course analysis to investigate whether tight glucose control significantly affected ketogenesis and to identify a day of maximal effect, if any. We quantified plasma/serum 3-hydroxybutyrate concentrations from intensive care unit admission until day 3 in 2 matched subsets of 100 critically ill children and 100 critically ill adults. Univariable differences between groups were investigated by Kruskal-Wallis test. Differences in 3-hydroxybutyrate concentrations between study days were investigated by Wilcoxon signed-rank test. Results In critically ill children and adults receiving early parenteral nutrition, tight glucose control, as compared with liberal glucose control, lowered mean morning blood glucose on days 1–3 (P < 0.0001) via infusing insulin at a higher dose (P < 0.0001). Throughout the study period, caloric intake was not different between groups. In both children and adults, tight glucose control did not affect 3-hydroxybutyrate concentrations, which were suppressed on ICU days 1–3 and significantly lower than the ICU admission values for both groups (P < 0.0001). Conclusion Tight versus liberal glucose control in the context of early parenteral nutrition did not affect 3-hydroxybutyrate concentrations in critically ill patients. Hence, the protective effects of tight glucose control in this context cannot be attributed to increased ketone body availability.

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Background Withholding parenteral nutrition (PN) until one week after PICU admission facilitated recovery from critical illness and protected against emotional and behavioral problems 4 years later. However, the intervention increased the risk of hypoglycemia, which may have counteracted part of the benefit. Previously, hypoglycemia occurring under tight glucose control in critically ill children receiving early PN did not associate with long-term harm. We investigated whether hypoglycemia in PICU differentially associates with outcome in the context of withholding early PN, and whether any potential association with outcome may depend on the applied glucose control protocol. Methods In this secondary analysis of the multicenter PEPaNIC RCT, we studied whether hypoglycemia in PICU associated with mortality (N = 1440) and 4-years neurodevelopmental outcome (N = 674) through univariable comparison and multivariable regression analyses adjusting for potential confounders. In patients with available blood samples (N = 556), multivariable models were additionally adjusted for baseline serum NSE and S100B concentrations as biomarkers of neuronal, respectively, astrocytic damage. To study whether an association of hypoglycemia with outcome may be affected by the nutritional strategy or center-specific glucose control protocol, we further adjusted the models for the interaction between hypoglycemia and the randomized nutritional strategy, respectively, treatment center. In sensitivity analyses, we studied whether any association with outcome was different in patients with iatrogenic or spontaneous/recurrent hypoglycemia. Results Hypoglycemia univariably associated with higher mortality in PICU, at 90 days and 4 years after randomization, but not when adjusted for risk factors. After 4 years, critically ill children with hypoglycemia scored significantly worse for certain parent/caregiver-reported executive functions (working memory, planning and organization, metacognition) than patients without hypoglycemia, also when adjusted for risk factors including baseline NSE and S100B. Further adjustment for the interaction of hypoglycemia with the randomized intervention or treatment center revealed a potential interaction, whereby tight glucose control and withholding early PN may be protective. Impaired executive functions were most pronounced in patients with spontaneous or recurrent hypoglycemia. Conclusion Critically ill children exposed to hypoglycemia in PICU were at higher risk of impaired executive functions after 4 years, especially in cases of spontaneous/recurrent hypoglycemia.

Introduction: In adults and children, withholding parenteral nutrition (PN) for 1 week in ICU (late PN), hereby accepting macronutrient deficit early during critical illness, as compared with supplementing insufficient enteral nutrition with PN (early PN), accelerates weaning from mechanical ventilation, reduces infections, and shortens ICU stay1,2. We hypothesized that these benefits are in part mediated by fasting-induced ketogenesis. Methods: This is a secondary analysis of the Early versus Late Parenteral Nutrition in the Pediatric ICU (PEPaNIC) RCT (N=1440)2. First, for a matched subset of 96 patients with a PICU stay of ≥5 days, daily plasma 3-hydroxybutyrate (3HB) concentrations were determined to identify the time point of maximal effect of late PN versus early PN, if any, on 3HB. Thereafter, for all patients with a plasma sample available on that “maximal effect day” (or last day for shorter stayers), plasma 3HB and insulin concentrations were quantified (N=1142). The independent association between plasma 3HB on that day and outcome was assessed by multivariable Cox proportional hazard analysis for time to live weaning from mechanical ventilation and for time to live PICU discharge and by multivariable logistic regression for incidence of new infection and PICU mortality, adjusted for randomization to late PN versus early PN and baseline risk factors (demographics, diagnosis, illness severity). In a sensitivity analysis, models were further adjusted for key regulators of ketogenesis (plasma insulin, blood glucose, corticosteroids and catecholamines) to assess whether any effect was direct or indirect. Results: In the matched cohort, late PN increased plasma 3HB as compared with early PN (P&lt;0.0001 for PICU-days 1 to 5), with maximal effect observed on PICU day 2. In the 1142 patients, plasma 3HB concentration on that “maximal effect day” was (mean±SEM) 0.19±0.05 mM in early PN patients and 1.17±0.02 mM in late-PN patients (P&lt;0.0001). Adding these plasma 3HB concentrations to the multivariable models, adjusted for baseline risk factors and randomization, showed that higher plasma 3HB concentrations were independently associated with a higher likelihood of early live weaning from mechanical ventilatory support (P=0.0002) and of early live PICU discharge (P=0.004). As the 3HB concentrations replaced the effect of the randomization, this suggested that the 3HB effect statistically explained these effects of the randomization. Further adjustment for key regulators of ketogenesis did not alter these findings. The effect of late PN versus early PN on plasma 3HB did not explain its impact on infections and was not related to mortality. Conclusion: Withholding early PN increased plasma 3HB concentrations in critically ill children, a direct effect that mediated an important part of its beneficial impact on recovery. 1Casaer M. et al, N Engl J Med 20112Fivez T. et al, N Engl J Med 2016