Association of early hyponatremia and the development of acute kidney injury in critically ill children.

BACKGROUND: Hyponatremia is an independent prognostic factor for mortality; however, the reason for this remains unclear. An observed relationship between hyponatremia and the development of acute kidney injury (AKI) has been reported in certain disease states, but hyponatremia has not been evaluated as a predictor of AKI in critically ill patients or children. METHODS: This is a single-center retrospective cohort study of critically ill children admitted to a tertiary care center. We performed regression analysis to assess the association between hyponatremia at ICU admission and the development of new or worsening stage 2 or 3 (severe) AKI on days 2-3 following ICU admission. RESULTS: Among the 5057 children included in the study, early hyponatremia was present in 13.3% of children. Severe AKI occurred in 9.2% of children with hyponatremia compared to 4.5% of children with normonatremia. Following covariate adjustment, hyponatremia at ICU admission was associated with a 75% increase in the odds of developing severe AKI when compared to critically ill children with normonatremia (aOR 1.75, 95% CI 1.28-2.39). Evaluating sodium levels continuously, for every 1 mEq/L decrease in serum sodium level, there was a 0.05% increase in the odds of developing severe AKI (aOR 1.05, 95% CI 1.02-1.08). Hyponatremic children who developed severe AKI had a higher frequency of kidney replacement therapy, AKI or acute kidney disease at hospital discharge, and hospital mortality when compared to those without. CONCLUSIONS: Hyponatremia at ICU admission is associated with the development of new or worsening AKI in critically ill children. A higher resolution version of the Graphical abstract is available as Supplementary information.

Association of Acute Kidney Injury With Subsequent Sepsis in Critically Ill Children.

OBJECTIVES: Acute kidney injury is a major cause of morbidity and mortality in critically ill children. A growing body of evidence has shown that acute kidney injury affects immune function, yet little is known about the association between acute kidney injury and subsequent infection in pediatric patients. Our objective was to examine the association of non-septic acute kidney injury with the development of subsequent sepsis in critically ill children. DESIGN: A single-center retrospective cohort study. SETTING: The pediatric and cardiac ICUs at a tertiary pediatric care center. PATIENTS: All patients 0-18 years old without a history of chronic kidney disease, who did not have sepsis prior to or within the initial 48 hours of ICU admission. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We analyzed data for 5,538 children (median age, 5.3 yr; 58.2% male), and identified 255 (4.6%) with stage 2 or 3 acute kidney injury. Suspected sepsis occurred in 46 children (18%) with stage 2 or 3 acute kidney injury compared to 286 children (5.4%) with stage 1 or no acute kidney injury. On adjusted analysis, children with stage 2 or 3 acute kidney injury had 2.05 times greater odds of developing sepsis compared to those with stage 1 or no acute kidney injury (95% CI, 1.39-3.03; p < 0.001). Looking at acute kidney injury severity, children with stage 2 and 3 acute kidney injury had a 1.79-fold (95% CI, 1.15-2.79; p = 0.01) and 3.24-fold (95% CI, 1.55-6.80; p = 0.002) increased odds of developing suspected sepsis, respectively. CONCLUSIONS: Acute kidney injury is associated with an increased risk for subsequent infection in critically ill children. These results further support the concept of acute kidney injury as a clinically relevant immunocompromised state.

Extra-renal manifestations of atypical hemolytic uremic syndrome.

Atypical hemolytic uremic syndrome (aHUS) is a rare and complex disease resulting from abnormal alternative complement activation with a wide range of clinical presentations. Extra-renal manifestations of aHUS can involve many organ systems, including the peripheral and central nervous, gastrointestinal, cardiovascular, integumentary, pulmonary, as well as the eye. While some of these extra-renal manifestations occur in the acute phase of aHUS, some can also occur as long-term sequelae of unopposed complement activation. Extra-renal symptoms are observed in approximately 20% of patients with aHUS, with the incidence of specific organ system complications ranging from a few case reports to 50% of described patients. Careful monitoring for extra-renal involvement is critical in patients with aHUS, as prompt evaluation and management may decrease the risk of high morbidity and mortality associated with aHUS.

Association of infections and venous thromboembolism in hospitalized children with nephrotic syndrome.

BACKGROUND: Nephrotic syndrome (NS) results in hypercoagulability and increased risk of infection. Furthermore, infection increases the risk of venous thromboembolism (VTE). Our objective was to determine the prevalence of infection, VTE, and the associated outcomes among a cohort of hospitalized children with NS. METHODS: All children with NS admitted to 17 pediatric hospitals across North America from 2010 to 2012 were included. Prevalence of infection and VTE was determined. Wilcoxon rank-sum and logistic regression were performed. RESULTS: Seven-hundred thirty hospitalizations occurred among 370 children with NS. One-hundred forty-eight children (40%) had ≥ 1 infection (211 episodes) and 11 (3%) had VTE. Those with VTE had infection more frequently (p = 0.046) and were younger at NS diagnosis (3.0 vs. 4.0 years; p = 0.008). The most common infectious pathogen identified was Streptococcus pneumoniae. The median hospital length of stay for those with infection [10 vs 5 days (p < 0.0001)] or VTE [22 vs 6 days (p < 0.0001)] was longer than those without either complication. Of those with infection, 13% had an intensive care unit (ICU) stay compared with 3.3% of those without infection. Median ICU stay was 4 days in those with VTE compared to 0 days in those without (p < 0.001). By logistic regression, only the number of ICU days was associated with VTE (OR 1.074, 95% CI 1.013-1.138). CONCLUSIONS: Hospitalized children with NS have high rates of infection. Presence of VTE was associated with infection. Both were associated with longer hospitalizations and ICU stays.

Subtypes and Mimics of Sepsis.

Sepsis is a heterogenous and imprecise syndrome that includes multiple phenotypes, some of which are amenable to specific therapies. Developing new therapies for sepsis will require focusing on subsets of patients. Key to improving care is evaluating patients for sepsis mimics and treatable diseases whose manifestations lead to a clinical classification of sepsis. Because sepsis is common, it is easy to overlook unusual causes of organ failure and succumb to confirmation bias about the nature of an illness. Careful attention to medical and family histories, focused diagnostic testing, and subspecialty input can help identify potentially treatable diseases masquerading as typical sepsis.

Uncommon Causes of Acute Kidney Injury.

Acute kidney injury (AKI) is one of the most important complications of critical illness and a significant public health concern. AKI is commonly associated with sepsis, cardiac dysfunction, and exposure to nephrotoxic medication; however, less common causes of AKI can lead to devastating patient outcomes when the underlying diagnosis is missed or delayed. These uncommon causes of AKI fall into 3 large categories: structural, immune mediated, and microvascular, including various types of thrombotic microangiopathy. Kidney imaging, urine studies, and serum hemolytic studies should be a routine part of the evaluation of AKI among critically ill patients.

Typical and Atypical Hemolytic Uremic Syndrome in the Critically Ill.

Hemolytic uremic syndrome is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Disseminated intravascular coagulation, thrombotic thrombocytopenic purpura, and hemolytic uremic syndrome have a similar clinical presentation. Diagnostic needs to be prompt to decrease mortality, because identifying the different disorders can help to tailor specific, effective therapies. However, diagnosis is challenging and morbidity and mortality remain high, especially in the critically ill population. Development of clinical prediction scores and rapid diagnostic tests for hemolytic uremic syndrome based on mechanistic knowledge are needed to facilitate early diagnosis and assign timely specific treatments to patients with hemolytic uremic syndrome variants.

Kidney-Immune System Crosstalk in AKI.

Acute kidney injury (AKI) now is recognized as a systemic disease. It occurs frequently in critically ill patients and has profound effects on morbidity and mortality. Recent research efforts have shown a bidirectional interplay between AKI and the immune system. Both innate and adaptive immune responses mediate renal injury as well as recovery from AKI. Dendritic cells, monocytes/macrophages, neutrophils, T lymphocytes, and B lymphocytes all play specific roles in the development of AKI. M2 macrophages and regulatory T cells also are pivotal in controlling inflammation, tissue remodeling, and repair after AKI. Conversely, existing evidence also suggests that increased production and decreased clearance of cytokines as well as dysfunction of immune cells, in particular neutrophils, can contribute to immune dysfunction and impaired bacterial clearance during AKI. Clinical data indicate that AKI is a risk factor for infections after various forms of critical illness, including cardiac surgery, malignancies, or severe trauma. Available evidence does not suggest that standard renal replacement therapies improve outcome from AKI beyond control of fluid balance and azotemia. Thus, novel approaches likely will be necessary to prevent or treat AKI-induced dysregulation of the inflammatory response.

AKI in Children Hospitalized with Nephrotic Syndrome.

BACKGROUND AND OBJECTIVES: Children with nephrotic syndrome can develop life-threatening complications, including infection and thrombosis. While AKI is associated with adverse outcomes in hospitalized children, little is known about the epidemiology of AKI in children with nephrotic syndrome. The main objectives of this study were to determine the incidence, epidemiology, and hospital outcomes associated with AKI in a modern cohort of children hospitalized with nephrotic syndrome. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Records of children with nephrotic syndrome admitted to 17 pediatric nephrology centers across North America from 2010 to 2012 were reviewed. AKI was classified using the pediatric RIFLE definition. RESULTS: AKI occurred in 58.6% of 336 children and 50.9% of 615 hospitalizations (27.3% in stage R, 17.2% in stage I, and 6.3% in stage F). After adjustment for race, sex, age at admission, and clinical diagnosis, infection (odds ratio, 2.24; 95% confidence interval, 1.37 to 3.65; P=0.001), nephrotoxic medication exposure (odds ratio, 1.35; 95% confidence interval, 1.11 to 1.64; P=0.002), days of nephrotoxic medication exposure (odds ratio, 1.10; 95% confidence interval, 1.05 to 1.15; P<0.001), and intensity of medication exposure (odds ratio, 1.34; 95% confidence interval, 1.09 to 1.65; P=0.01) remained significantly associated with AKI in children with nephrotic syndrome. Nephrotoxic medication exposure was common in this population, and each additional nephrotoxic medication received during a hospitalization was associated with 38% higher risk of AKI. AKI was associated with longer hospital stay after adjustment for race, sex, age at admission, clinical diagnosis, and infection (difference, 0.45 [log]days; 95% confidence interval, 0.36 to 0.53 [log]days; P<0.001). CONCLUSIONS: AKI is common in children hospitalized with nephrotic syndrome and should be deemed the third major complication of nephrotic syndrome in children in addition to infection and venous thromboembolism. Risk factors for AKI include steroid-resistant nephrotic syndrome, infection, and nephrotoxic medication exposure. Children with AKI have longer hospital lengths of stay and increased need for intensive care unit admission.