Initial lactate levels linked to oliguria in term neonates with perinatal asphyxia.

BACKGROUND: Oliguria is a sign of impaired kidney function and has been shown to be an early predictor of adverse prognoses in patients with acute kidney injury. The relationship between urine output (UOP) and early lactate levels in neonates with perinatal asphyxia (PA) has not been extensively explored. This study aimed to investigate the link between oliguria during the first 24 h of life and early lactate levels in neonates with PA. METHODS: The medical records of 293 term neonates with asphyxia from 9216 hospitalized newborns were retrospectively analyzed, including 127 cases designated as the oliguria group and 166 cases as controls. Peripheral arterial blood gas after PA and UOP within 24 h after birth were analyzed. Logistic regression analyses and receiver operating characteristic curve analysis were conducted. RESULTS: Oliguria occurred in 43.34% of neonates with PA. The median UOP of the oliguria and control groups were 0.65 and 1.46 mL/kg/h, respectively. Elevated lactate levels after PA are an independent risk factor for oliguria in the following 24 h (p = 0.01; OR: 1.19; 95%CI: 1.04-1.35) and show a moderate discriminatory power for oliguria (AUC = 0.62). Using a cut off value of 8.15 mmol/L, the positive and negative predictive values and the specificity were 59.34%, 63.86%, and 78.30%, respectively. CONCLUSION: Neonates with elevated lactate levels after PA face a risk of oliguria in the following 24 h. Based on early elevated lactate levels after resuscitation, especially ≥ 8.15 mmol/L, meticulously monitoring UOP will allow this vulnerable population to receive early, tailored fluid management and medical intervention.

Explainable machine learning model for predicting furosemide responsiveness in patients with oliguric acute kidney injury.

BACKGROUND: Although current guidelines didn't support the routine use of furosemide in oliguric acute kidney injury (AKI) management, some patients may benefit from furosemide administration at an early stage. We aimed to develop an explainable machine learning (ML) model to differentiate between furosemide-responsive (FR) and furosemide-unresponsive (FU) oliguric AKI. METHODS: From Medical Information Mart for Intensive Care-IV (MIMIC-IV) and eICU Collaborative Research Database (eICU-CRD), oliguric AKI patients with urine output (UO) < 0.5 ml/kg/h for the first 6 h after ICU admission and furosemide infusion ≥ 40 mg in the following 6 h were retrospectively selected. The MIMIC-IV cohort was used in training a XGBoost model to predict UO > 0.65 ml/kg/h during 6-24 h succeeding the initial 6 h for assessing oliguria, and it was validated in the eICU-CRD cohort. We compared the predictive performance of the XGBoost model with the traditional logistic regression and other ML models. RESULTS: 6897 patients were included in the MIMIC-IV training cohort, with 2235 patients in the eICU-CRD validation cohort. The XGBoost model showed an AUC of 0.97 (95% CI: 0.96-0.98) for differentiating FR and FU oliguric AKI. It outperformed the logistic regression and other ML models in correctly predicting furosemide diuretic response, achieved 92.43% sensitivity (95% CI: 90.88-93.73%) and 95.12% specificity (95% CI: 93.51-96.3%). CONCLUSION: A boosted ensemble algorithm can be used to accurately differentiate between patients who would and would not respond to furosemide in oliguric AKI. By making the model explainable, clinicians would be able to better understand the reasoning behind the prediction outcome and make individualized treatment.

Early detection of oliguric events in critically ill patients in the ICU with a novel continuous urine flow measurement device: results of an initial validation study.

OBJECTIVES: Urine output is used to evaluate fluid status and is an important marker for acute kidney injury (AKI). Our primary aim was to validate a new automatic urine output monitoring device by comparison to the current practice - the standard urometer. METHODS: We conducted a prospective observational study in three ICUs. Urine flow measurements by Serenno Medical Automatic urine output measuring device (Serenno Medical, Yokneam, Israel) were compared to standard urometer readings taken automatically at 5-minutes intervals by a camera, and to hourly urometer readings by the nurses, both over 1 to 7 days. Our primary outcome was the difference between urine flow assessed by the Serenno device and reference camera-derived measurements (Camera). Our secondary outcome was the difference between urine flow assessed by the Serenno device and hourly nursing assessments (Nurse), and detection of oliguria. RESULTS: Thirty-seven patients completed the study, with 1,306 h of recording and a median of 25 measurement hours per patient. Bland and Altman analysis comparing the study device to camera measurements demonstrated good agreement, with a bias of -0.4 ml/h and 95% confidence intervals ranging from - 28 to 27ml/h. Concordance was 92%. The correlation between Camera and hourly nursing assessment of urine output was distinctly worse with a bias of 7.2 ml and limits of agreement extending from - 75 to + 107 ml. Severe oliguria (urine output < 0.3 ml/kg/h) lasting 2 h or more was common and observed in 8 (21%) of patients. Among the severe oliguric events lasting more than 3 consecutive hours, 6 (41%) were not detected or documented by the nursing staff. There were no device-related complications. CONCLUSION: The Serenno Medical Automatic urine output measuring device required minimal supervision, little ICU nursing staff attention, and is sufficiently accurate and precise. In addition to providing continuous assessments of urine output, it was considerably more accurate than hourly nursing assessments.

Assessment of prognostic value of intraoperative oliguria for postoperative acute kidney injury: a retrospective cohort study.

BACKGROUND: Oliguria is often viewed as a sign of renal hypoperfusion and an indicator for volume expansion during surgery. However, the prognostic association and the predictive utility of intraoperative oliguria for postoperative acute kidney injury (AKI) are unclear. METHODS: We conducted a retrospective cohort study on patients undergoing major thoracic surgery in an academic hospital to assess the association of intraoperative oliguria with postoperative AKI and its predictive value. To contextualise our findings, we included our results in a meta-analysis of observational studies on the importance of oliguria during noncardiac surgery. RESULTS: In our cohort study, 3862 patients were included; 205 (5.3%) developed AKI after surgery. Intraoperative urine output of 0.3 ml kg-1 h-1 was the optimal threshold for oliguria in multivariable analysis. Patients with oliguria had an increased risk of AKI (adjusted odds ratio: 2.60; 95% confidence interval: 1.24-5.05). However, intraoperative oliguria had a sensitivity of 5.9%, specificity of 98%, positive likelihood ratio of 2.74, and negative likelihood ratio of 0.96, suggesting poor predictive ability. Moreover, it did not improve upon the predictive performance of a multivariable model, based on discrimination and reclassification indices. Our findings were generally consistent with the results of a systematic review and meta-analysis, including six additional studies. CONCLUSIONS: Intraoperative oliguria has moderate association with, but poor predictive ability for, postoperative AKI. It remains of clinical interest as a risk factor potentially modifiable to interventions.

Acute kidney injury after liver surgery: does postoperative urine output correlate with postoperative serum creatinine?

BACKGROUND: Acute kidney injury (AKI) after hepatectomy occurs in around 10% of cases. AKI is often defined based only on postoperative serum creatinine increase. This study aimed to assess if postoperative urine output (UO) correlated with serum creatinine after hepatectomy. METHODS: All consecutive hepatectomy patients (2010-2016) were assessed. AKI was defined according to KDIGO criteria: serum creatinine increase ≥26.5 µmol/l, creatinine increase ≥1.5x baseline creatinine, or postoperative oliguria. Oliguria was defined as daily mean UO <0.5 mL/kg/h. AKI was subdivided into creatinine-based or oliguria-based AKI according to the defining criterion. RESULTS: Out of 285 patients, AKI was observed in 79 cases (28%). Creatinine-based AKI occurred in 25 patients (9%) and oliguria-based only AKI in 54 patients (19%). Ten patients fulfilled both criteria (4%). Postoperative UO correlated poorly with postoperative serum creatinine level in both whole cohort (rho = -0.34, p <0.001) and AKI subgroup (rho = -0.189, p = 0.124). No association was found between postoperative oliguria and postoperative serum creatinine increase (HR = 0.5, 95%CI: 0.2-1.9, p = 0.341). On multivariable analysis, operation duration >360 minutes was the only predictor of creatinine increase (HR = 3.6, 95%CI: 1.1-11.4, p = 0.032). CONCLUSION: Postoperative UO showed poor correlation with postoperative serum creatinine both in all patients and AKI patients. Surgery duration >360 minutes appeared as the only independent predictor of postoperative serum creatinine increase.

Oliguria and Acute Kidney Injury in Critically Ill Children: Implications for Diagnosis and Outcomes.

OBJECTIVES: Consensus definitions for acute kidney injury are based on changes in serum creatinine and urine output. Although the creatinine criteria have been widely applied, the contribution of the urine output criteria remains poorly understood. We evaluated these criteria individually and collectively to determine their impact on the diagnosis and outcome of severe acute kidney injury. DESIGN AND SETTING: Post hoc analysis of Assessment of Worldwide Acute Kidney Injury, Renal Angina, and Epidemiology study-a prospective international observational multicenter study. PATIENTS: Critically ill children enrolled in Assessment of Worldwide Acute Kidney Injury, Renal Angina and, Epidemiology database. MEASUREMENT: To assess the differential impact of creatinine and urine output criteria on severe acute kidney injury (Kidney Disease: Improving Global Outcomes stage ≥ 2). Patients were divided into four cohorts: no-severe acute kidney injury, severe acute kidney injury by creatinine criteria only, severe acute kidney injury by urine output criteria only, and severe acute kidney injury by both creatinine and urine output criteria. RESULTS: Severe acute kidney injury occurred in 496 of 3,318 children (14.9%); 343 (69.2%) were creatinine criteria only, 90 (18.1%) were urine output criteria only, and 63 (12.7%) were both creatinine and urine output criteria. Twenty-eight-day mortality for creatinine criteria only and urine output criteria only patients was similar (6.7% vs 7.8%) and higher than those without severe acute kidney injury (2.9%; p < 0.01). Both creatinine and urine output criteria patients had higher mortality than creatinine criteria only and urine output criteria only patients (38.1%; p < 0.001). Compared with patients without severe acute kidney injury, the relative risk of receiving dialysis increased from 9.1 (95% CI, 3.9-21.2) in creatinine criteria only, to 28.2 (95% CI, 11.8-67.7) in urine output criteria only, to 165.7 (95% CI, 86.3-318.2) in both creatinine and urine output criteria (p < 0.01). CONCLUSIONS: Nearly one in five critically ill children with acute kidney injury do not experience increase in serum creatinine. These acute kidney injury events, which are only identified by urine output criteria, are associated with comparably poor outcomes as those diagnosed by changes in creatinine. Children meeting both criteria had worse outcomes than those meeting only one. We suggest oliguria represents a risk factor for poorer outcomes among children who develop acute kidney injury. Application of both the creatinine and urine output criteria leads to a more comprehensive epidemiologic assessment of acute kidney injury and identifies a subset of children with acute kidney injury who are at higher risk for morbidity and mortality.

Association Between Intraoperative Oliguria and Acute Kidney Injury After Major Noncardiac Surgery.

BACKGROUND: Acute kidney injury (AKI) occurs in 6.1%-22.4% of patients undergoing major noncardiac surgery. Previous studies have shown no association between intraoperative urine output and postoperative acute renal failure. However, these studies used various definitions of acute renal failure. We therefore investigated the association between intraoperative oliguria and postoperative AKI defined by the serum creatinine criteria of the Risk, Injury, Failure, Loss, and End-stage kidney disease (RIFLE) classification. METHODS: In this single-center, retrospective, observational study, we screened 26,984 patients undergoing elective or emergency surgery during the period September 1, 2008 to October 31, 2011 at a university hospital. Exclusion criteria were age <18 years; duration of anesthesia <120 minutes; hospital stay <2 nights; local anesthesia only; urologic or cardiac surgery; coexisting end-stage kidney disease; and absence of serum creatinine measurement, intraoperative urine output data, or information regarding intraoperative drug use. Multivariable logistic regression analysis was used as the primary analytic method. RESULTS: A total of 5894 patients were analyzed. The incidence of postoperative AKI was 7.3%. By multivariable analysis, ≥120 minutes of oliguria (odds ratio = 2.104, 95% CI, 1.593-2.778; P < .001) was independently associated with the development of postoperative AKI. After propensity-score matching of patients with ≥120 and <120 minutes of oliguria on baseline characteristics, the incidence of AKI in patients with ≥120 minutes of oliguria (n = 827; 10%) was significantly greater than that in those with <120 minutes of oliguria (n = 827; 4.8%; odds ratio = 2.195, 95% CI, 1.806-2.668; P < .001). CONCLUSIONS: Contrary to previous studies, we found that intraoperative oliguria is associated with the incidence of AKI after major noncardiac surgery.

Update on Perioperative Acute Kidney Injury.

Acute kidney injury (AKI) in the perioperative period is a common complication and is associated with increased morbidity and mortality. A standard definition and staging system for AKI has been developed, incorporating a reduction of the urine output and/or an increase of serum creatinine. Novel biomarkers may detect kidney damage in the absence of a change in function and can also predict the development of AKI. Several specific considerations for AKI risk are important in surgical patients. The surgery, especially major and emergency procedures in critically ill patients, may cause AKI. In addition, certain comorbidities, such as chronic kidney disease and chronic heart failure, are important risk factors for AKI. Diuretics, contrast agents, and nephrotoxic drugs are commonly used in the perioperative period and may result in a significant amount of in-hospital AKI. Before and during surgery, anesthetists are supposed to optimize the patient, including preventing and treating a hypovolemia and correcting an anemia. Intraoperative episodes of hypotension have to be avoided because even short periods of hypotension are associated with an increased risk of AKI. During the intraoperative period, urine output might be reduced in the absence of kidney injury or the presence of kidney injury with or without fluid responsiveness. Therefore, fluids should be used carefully to avoid hypovolemia and hypervolemia. The Kidney Disease: Improving Global Outcomes guidelines suggest implementing preventive strategies in high-risk patients, which include optimization of hemodynamics, restoration of the circulating volume, institution of functional hemodynamic monitoring, and avoidance of nephrotoxic agents and hyperglycemia. Two recently published studies found that implementing this bundle in high-risk patients reduced the occurrence of AKI in the perioperative period. In addition, the application of remote ischemic preconditioning has been studied to potentially reduce the incidence of perioperative AKI. This review discusses the epidemiology and pathophysiology of surgery-associated AKI, highlights the importance of intraoperative oliguria, and emphasizes potential preventive strategies.

[Preliminary study of the arm equilibrium pressure to predict the effect of fluid challenge on urine output in oliguric intensive care unit patients].

Objective: To evaluate whether arm equilibrium pressure (Parm) is helpful to predict the effect of fluid load in improving oliguria in intensive care unit(ICU) patients. Methods: Hemodynamically stable patients [mean artery pressure (MAP)>65 mmHg (1 mmHg=0.133 kPa), heart rate (HR)<120 beats/min, lactic acid<2 mmol/L] with urine output (UO)<0.5 ml·kg(-1)·h(-1) for 3 consecutive hours were enrolled. The fluid loading was performed by infusion of ringer's lactate 500 ml within 30 minute after baseline hemodynamic data were recorded. The positive renal response was defined as UO increased more than 0.5 ml·kg(-1)·h(-1) 1 hour after fluid challenge, otherwise was negative. Results: A total of 30 oliguric ICU patients were enrolled including 17 males and 13 females with median age (54.2±16.3) years. After fluid load, patients' HR decreased[(84±13)beat/min vs. (80±10) beat/min, P<0.01], central venous pressure (CVP) increased[(7.0±2.4)mmHg vs. (8.8±2.6) mmHg, P<0.01], 30s Parm [(33.4±5.3) mmHg vs. (35.4±5.8) mmHg, P<0.01] and 60s Parm [(26.9±4.5) mmHg vs. (28.7±5.0) mmHg, P<0.01] increased, and UO [(18.5±8.8)ml/h vs. (64.1±38.3)ml/h, P<0.01] increased significantly, while MAP and lactic acid did not change (P>0.05). There were eighteen renal responders and 12 patients did not response. In responding group, MAP[(78.1±10.7) mmHg vs. (91.2±11.7) mmHg, P<0.01], 30s Parm[(30.4±3.8) mmHg vs. (38.0±3.7) mmHg, P<0.01] and 60s Parm [(24.3±2.5) mmHg vs. (30.8±4.0) mmHg, P<0.01] before fluid load were lower than those in negative group. HR, CVP, lactic acid, age and body weight were comparable between two groups (P>0.05). After volume loading, MAP, 30s and 60s Parm in positive group were still lower than those in negative group (P<0.05), while HR, CVP and lactic acid were similar (P>0.05). Correlation analysis showed that baseline 30s Parm (r=-0.75, P<0.01), 60s Parm (r=-0.69, P<0.01), and MAP (r=-0.46, P<0.05) were negatively correlated with 1 h UO after fluid load, but HR and CVP were not (P>0.05). The receiver operating curve (ROC) showed that 30s Parm had the largest area under curve (AUC) of 0.94 (95% CI 0.84-1.05, P<0.01), which 35.5 mmHg was the best threshold with sensitivity 94.4% and specificity 91.7%(likelihood ratio 11.37). Conclusion: In hemodynamically stable oliguric ICU patients, if Parm is lower than normal reference value, volume expansion is more likely to increase UO. Thus Parm can be used to predict the effect of fluid loadon UO.

Increased urinary neutrophil gelatinase-associated lipocalin in very-low-birth-weight infants with oliguria and normal serum creatinine.

BACKGROUND: In infants, oliguria is defined as a urine output of <1.5 mL/kg/h. The aim of our study was to assess the impact of oliguria on urinary neutrophil gelatinase-associated lipocalin (NGAL) and serum cystatin C (CysC) levels in very-low-birth-weight infants (VLBWIs) with a normal serum creatinine (Cr) level. METHODS: Fifty-seven VLBWIs were enrolled in the study. Urinary NGAL, serum CysC and Cr levels and urinary NGAL/Cr ratios were measured. Infants with Apgar scores of >5 at 5 min and/or a serum Cr level of >1.5 mg/dL or those treated for patent ductus arteriosus were excluded. In case of antibiotic treatment, blood and urine samples were collected at ≥48 h after discontinuation of antibiotic treatment. RESULTS: There was a significant difference in gestational age between infants with oliguric episodes during hospitalization and those without, but not in birth weight, perinatal or postnatal factors. Gestational age was negatively correlated with urinary NGAL and serum CysC levels and urinary NGAL/Cr ratio (p < 0.05), whereas postnatal age was negatively correlated with serum Cr level and urinary NGAL/Cr ratio (p < 0.05). Of the 117 urine and blood samples collected, 25 (21.4%) were obtained from neonates with oliguric episodes. After adjusting for gestational age and postnatal age, comparison of samples collected in infants with and without oliguric episodes revealed significant differences in the mean level of urinary NGAL and in the urinary NGAL/Cr ratio, but not in mean serum CysC or serum Cr levels. The urinary NGAL level [area under the curve (AUC) 0.886, 95% confidence interval (CI) 0.814-0.937] and urinary NGAL/Cr ratio (AUC 0.853, 95% CI 0.775-0.911) showed significantly greater discrimination for oliguria than serum CysC (AUC 0.610, 95% CI: 0.515-0.699) or serum Cr (AUC 0.747, 95%CI 0.659-0.823) levels. CONCLUSIONS: Urinary NGAL level and urinary NGAL/Cr ratio were more sensitive markers for the presence of oliguria in VLBWIs with normal serum Cr levels than serum CysC level.

Acute kidney injury and fluid overload in infants and children after cardiac surgery.

Acute kidney injury is a common and serious complication after congenital heart surgery, particularly among infants. This comorbidity has been independently associated with adverse outcomes including an increase in mortality. Postoperative acute kidney injury has a complex pathophysiology with many risk factors, and therefore no single medication or therapy has been demonstrated to be effective for treatment or prevention. However, it has been established that the associated fluid overload is one of the major determinants of morbidity, particularly in infants after cardiac surgery. Therefore, in the absence of an intervention to prevent acute kidney injury, much of the effort to improve outcomes has focused on treating and preventing fluid overload. Early renal replacement therapy, often in the form of peritoneal dialysis, has been shown to be safe and beneficial in infants with oliguria after heart surgery. As understanding of the pathophysiology of acute kidney injury and the ability to confidently diagnose it earlier continues to evolve, it is likely that novel preventative and therapeutic interventions will be available in the future.

Urine sodium concentration to predict fluid responsiveness in oliguric ICU patients: a prospective multicenter observational study.

BACKGROUND: Oliguria is one of the leading triggers of fluid loading in patients in the intensive care unit (ICU). The purpose of this study was to assess the predictive value of urine Na(+) (uNa(+)) and other routine urine biomarkers for cardiac fluid responsiveness in oliguric ICU patients. METHODS: We conducted a prospective multicenter observational study in five university ICUs. Patients with urine output (UO) <0.5 ml/kg/h for 3 consecutive hours with a mean arterial pressure >65 mmHg received a fluid challenge. Cardiac fluid responsiveness was defined by an increase in stroke volume >15 % after fluid challenge. Urine and plasma biochemistry samples were examined before fluid challenge. We examined renal fluid responsiveness (defined as UO > 0.5 ml/kg/h for 3 consecutive hours) after fluid challenge as a secondary endpoint. RESULTS: Fifty-four patients (age 51 ± 37 years, Simplified Acute Physiology Score II score 40 ± 20) were included. Most patients (72 %) were not cardiac responders (CRs), and 50 % were renal responders (RRs) to fluid challenge. Patient characteristics were similar between CRs and cardiac nonresponders. uNa(+) (37 ± 38 mmol/L vs 25 ± 75 mmol/L, p = 0.44) and fractional excretion of sodium (FENa(+)) (2.27 ± 2.5 % vs 2.15 ± 5.0 %, p = 0.94) were not statistically different between those who did and those who did not respond to the fluid challenge. Areas under the receiver operating characteristic (AUROC) curves were 0.51 (95 % CI 0.35-0.68) and 0.56 (95 % CI 0.39-0.73) for uNa(+) and FENa(+), respectively. Fractional excretion of urea had an AUROC curve of 0.70 (95 % CI 0.54-0.86, p = 0.03) for CRs. Baseline UO was higher in RRs than in renal nonresponders (1.07 ± 0.78 ml/kg/3 h vs 0.65 ± 0.53 ml/kg/3 h, p = 0.01). The AUROC curve for RRs was 0.65 (95 % CI 0.53-0.78) for uNa(+). CONCLUSIONS: In the present study, most oliguric patients were not CRs and half were not renal responders to fluid challenge. Routine urinary biomarkers were not predictive of fluid responsiveness in oliguric normotensive ICU patients.

Defining oliguria during cardiopulmonary bypass and its relationship with cardiac surgery-associated acute kidney injury.

BACKGROUND: While urine flow rate ≤0.5 ml kg-1 h-1 is believed to define oliguria during cardiopulmonary bypass (CPB), it is unclear whether this definition identifies risk for acute kidney injury (AKI) . The purpose of this retrospective study was to evaluate if urine flow rate during CPB is associated with AKI. METHODS: Urine flow rate was calculated in 503 patients during CPB. AKI in the first 48 h after surgery was defined by the Kidney Disease: Improving Global Outcomes classification. Adjusted risk factors associated with AKI and urine flow rate were assessed. RESULTS: Patients with AKI [n=149 (29.5%)] had lower urine flow rate than those without AKI (P<0.001). The relationship between urine flow and AKI risk was non-linear, with an inflection point at 1.5 ml kg-1 h-1 Among patients with urine flow <1.5 ml kg-1 h-1, every 0.5 ml kg-1 h-1 higher urine flow reduced the adjusted risk of AKI by 26% (95% CI 13-37; P<0.001). Urine flow rate during CPB was independently associated with the risk for AKI. Age up to 80 years and preoperative diuretic use were inversely associated with urine flow rate; mean arterial pressure on CPB (when <87 mmHg) and CPB flow were positively associated with urine flow rate. CONCLUSIONS: Urine flow rate during CPB <1.5 ml kg-1 h-1 identifies patients at risk for cardiac surgery-associated AKI. Careful monitoring of urine flow rate and optimizing mean arterial pressure and CPB flow might be a means to ensure renal perfusion during CPB. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov NCT00769691 and NCT00981474.

Targeting Oliguria Reversal in Goal-Directed Hemodynamic Management Does Not Reduce Renal Dysfunction in Perioperative and Critically Ill Patients: A Systematic Review and Meta-Analysis.

BACKGROUND: We investigated whether resuscitation protocols to achieve and maintain urine output above a predefined threshold-including oliguria reversal as a target--prevent acute renal failure (ARF). METHODS: We performed a systematic review and meta-analysis using studies found by searching MEDLINE, EMBASE, and references in relevant reviews and articles. We included all studies that compared "conventional fluid management" (CFM) with "goal-directed therapy" (GDT) using cardiac output, urine output, or oxygen delivery parameters and reported the occurrence of ARF in critically ill or surgical patients. We divided studies into groups with and without oliguria reversal as a target for hemodynamic optimization. We calculated the combined odds ratio (OR) and 95% confidence intervals (CIs) using random-effects meta-analysis. RESULTS: We based our analyses on 28 studies. In the overall analysis, GDT resulted in less ARF than CFM (OR, 0.58; 95% CI, 0.44-0.76; P < 0.001; I = 34.3%; n = 28). GDT without oliguria reversal as a target resulted in less ARF (OR, 0.45; 95% CI, 0.34-0.61; P < 0.001; I = 7.1%; n = 7) when compared with CFM with oliguria reversal as a target. The studies comparing GDT with CFM in which the reversal of oliguria was targeted in both or in neither group did not provide enough evidence to conclude a superiority of GDT (targeting oliguria reversal in both protocols: OR, 0.63; 95% CI, 0.36-1.10; P = 0.09; I = 48.6%; n = 9, and in neither protocol: OR, 0.66; 95% CI, 0.37-1.16; P = 0.14; I = 20.2%; n = 12). CONCLUSIONS: Current literature favors targeting circulatory optimization by GDT without targeting oliguria reversal to prevent ARF. Future studies are needed to investigate the hypothesis that targeting oliguria reversal does not prevent ARF in critically ill and surgical patients.

Prediction of urine volume soon after birth using serum cystatin C.

BACKGROUND: Urine volume is an important clinical finding particularly during the early neonatal period. Oliguria is not a sign of impaired renal function but also a predictive factor for various complications and prognoses. It has been postulated that serum cystatin C (S-CysC) is a more sensitive biomarker for renal function than serum creatinine (S-Cr) in both adults and children. The objective of the current study was to investigate whether urine volume during 24 h after birth can be predicted using S-CysC. METHODS: The subjects were 87 infants. The average gestational age was 34.7 ± 2.9 weeks and the average birth weight was 2135 ± 614 g. Blood samples were obtained from either the umbilical cord or the peripheral veins or artery of the newborn at birth. Data regarding the amount of urine volume and fluid intake during the first 24 h of life, maternal S-Cr and S-CysC levels within 48 h before delivery, and neonatal S-Cr and S-CysC levels at birth were collected from the medical records. RESULTS: A significantly positive correlation was observed between maternal and neonatal S-Cr levels (r = 0.84, p < 0.0001) but not between maternal S-Cr levels and neonatal S-CysC levels (r = -0.069, p = 0.52). A significant negative correlation was seen between neonatal S-CysC levels and urine volume (r = -0.47, p < 0.0001). CONCLUSION: The present study findings indicate that it may be possible to use S-CysC levels at birth to predict urine volume during the first 24 h of life.

Risk factors for loss of residual renal function in children treated with chronic peritoneal dialysis.

In dialyzed patients, preservation of residual renal function is associated with better survival, lower morbidity, and greater quality of life. To analyze the evolution of residual diuresis over time, we prospectively monitored urine output in 401 pediatric patients in the global IPPN registry who commenced peritoneal dialysis (PD) with significant residual renal function. Associations of patient characteristics and time-variant covariates with daily urine output and the risk of developing oligoanuria (under 100 ml/m(2)/day) were analyzed by mixed linear modeling and Cox regression analysis including time-varying covariates. With an average loss of daily urine volume of 130 ml/m(2) per year, median time to oligoanuria was 48 months. Residual diuresis significantly subsided more rapidly in children with glomerulopathies, lower diuresis at start of PD, high ultrafiltration volume, and icodextrin use. Administration of diuretics significantly reduced oligoanuria risk, whereas the prescription of renin-angiotensin system antagonists significantly increased the risk oligoanuria. Urine output on PD was significantly associated in a negative manner with glomerulopathies (-584 ml/m(2)) and marginally with the use of icodextrin (-179 ml/m(2)) but positively associated with the use of biocompatible PD fluid (+111 ml/m(2)). Children in both Asia and North America had consistently lower urine output compared with those in Europe perhaps due to regional variances in therapy. Thus, in children undergoing PD, residual renal function depends strongly on the cause of underlying kidney disease and may be modifiable by diuretic therapy, peritoneal ultrafiltration, and choice of PD fluid.

Acute kidney injury after cardiac arrest.

INTRODUCTION: The aim of this study was to evaluate the incidence and determinants of AKI in a large cohort of cardiac arrest patients. METHODS: We reviewed all patients admitted, for at least 48 hours, to our Dept. of Intensive Care after CA between January 2008 and October 2012. AKI was defined as oligo-anuria (daily urine output <0.5 ml/kg/h) and/or an increase in serum creatinine (≥0.3 mg/dl from admission value within 48 hours or a 1.5 time from baseline level). Demographics, comorbidities, CA details, and ICU interventions were recorded. Neurological outcome was assessed at 3 months using the Cerebral Performance Category scale (CPC 1-2 = favorable outcome; 3-5 = poor outcome). RESULTS: A total of 199 patients were included, 85 (43%) of whom developed AKI during the ICU stay. Independent predictors of AKI development were older age, chronic renal disease, higher dose of epinephrine, in-hospital CA, presence of shock during the ICU stay, a low creatinine clearance (CrCl) on admission and a high cumulative fluid balance at 48 hours. Patients with AKI had higher hospital mortality (55/85 vs. 57/114, p = 0.04), but AKI was not an independent predictor of poor 3-month neurological outcome. CONCLUSIONS: AKI occurred in more than 40% of patients after CA. These patients had more severe hemodynamic impairment and needed more aggressive ICU therapy; however the development of AKI did not influence neurological recovery.

Interdialytic weight gain in oligoanuric children and adolescents on chronic hemodialysis.

BACKGROUND: Little is known about the clinical impact of interdialytic weight gain (IDWG) on oligoanuric children undergoing chronic hemodialysis (HD). METHODS: We retrospectively assessed IDWG, left ventricular mass index (LVMI) and its changes (ΔLVMI), pre-HD systolic and diastolic blood pressure (DBP), residual urine output, Kt/V, the frequency of intradialytic symptoms, normalized protein catabolic rate, and the 3-month change in the dry weight of 16 hemodialyzed oligoanuric patients with a median age of 14.8 years (range 5.0-17.9). RESULTS: There was a significant correlation between IDWG and median LVMI (r 0.55, p = 0.026), which was 27.3 g/m(2.7) (22.5-37.6) in the patients with a median IDWG of <4 %, and 44.3 g/m(2.7) (28.2-68.7) in those with a median IDWG of >4 % (p = 0.003). None of the four patients with an IDWG of <4 % showed left ventricular hypertrophy, compared with 10 of the 12 patients (83.3 %) with an IDWG of >4 % (p = 0.003); the former also had a better median ΔLVMI (-33.5 % vs -13.0 %; p = 0.02) and a lower median DBP sds (0.24 vs 1.72, p = 0.04). CONCLUSIONS: There is a significant correlation between IDWG and LVMI in pediatric oligoanuric patients on chronic HD: those with an IDWG of >4 % are at a higher risk of left ventricular hypertrophy.

Pathophysiology and management of acute kidney injury in the setting of abdominal compartment syndrome.

Abdominal compartment syndrome (ACS) is defined as an organ dysfunction caused by intra-abdominal hypertension (IAH). Up to 4.2% of the patients in intensive care unit may develop IAH with it being an independent predictor of mortality. However, overall, it still remains a relatively underdiagnosed condition, part in because physical examination alone is very unreliable. Acute kidney injury is one of the most consistently described organ dysfunctions with oliguria being one of the earliest clinical signs of IAH. We recommend that any patient with evidence of new onset oliguria in the setting of distended abdomen, unexplained respiratory failure, with or without hypotension should be suspected of having IAH/ACS. Intravesicular pressure measurement represents a safe, rapid, and cost-effective method of diagnosing IAH. We hereby review the pathophysiology, diagnosis, and management of ACS and its association with acute kidney injury.