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.

Urine volume as a predicting factor for furosemide clearance during continuous infusion in AKI septic shock patients on hemodiafiltration.

BACKGROUND: This study assessed the contribution of intracorporeal (IC) and extracorporeal clearance (EC) of furosemide in patients with septic acute kidney injury (AKI), and the relationship between plasma concentrations and urine volume. METHODS: Prospective cohort observational study of 15 patients with septic AKI undergoing continuous veno-venous hemodiafiltration (CVVHDF) divided according to urine volume (< 500 ml/12 h, Oliguria group, n = 5; > 500 ml/12 h, Diuresis group, n = 10) during continuous infusion of furosemide (120 mg/12 h) at steady-state condition. Plasma and effluent furosemide concentrations were determined by high-performance liquid chromatography (HPLC)-mass spectrometry every 12 h for 48 h. RESULTS: Furosemide plasma concentrations and total body clearance (TBC) were 6.14 mg/l and 22.1 ml/min for the Oliguria group, and 2.63 mg/l and 54.4 ml/min for the Diuresis group, respectively (p < 0.05). When urine volume was < 500 ml/24 h, the furosemide plasma concentrations peaked at the potentially toxic value of 13.0 mg/l. Furosemide EC was not relevant for the Diuresis group, but it represented 18% of TBC for the Oliguria group. Furosemide plasma concentrations correlated positively with dose infusion for both groups (r = 0.728 and 0.685, p < 0.05), and negatively with urine volume only for the Diuresis (r = - 0.578, p < 0.01) but not for the Oliguria group (r = - 0.089, p = 0.715). CONCLUSIONS: For patients with urine volume > 500 ml/12 h continuous infusion of furosemide up to 480 mg/24 h leads to increasing urine volume, which can predict furosemide plasma levels within its safety range. When the urine volume is lower, the furosemide plasma levels are increased beyond any further diuretic efficacy.

Intraoperative oliguria predicts acute kidney injury after major abdominal surgery.

Background: The threshold of intraoperative urine output below which the risk of acute kidney injury (AKI) increases is unclear. The aim of this retrospective cohort study was to investigate the relationship between intraoperative urine output during major abdominal surgery and the development of postoperative AKI and to identify an optimal threshold for predicting the differential risk of AKI. Methods: Perioperative data were collected retrospectively on 3560 patients undergoing major abdominal surgery (liver, colorectal, gastric, pancreatic, or oesophageal resection) at Kyoto University Hospital. We evaluated the relationship between intraoperative urine output and the development of postoperative AKI as defined by recent guidelines. Logistic regression analysis was performed to adjust for patient and operative variables, and the minimum P -value approach was used to determine the threshold of intraoperative urine output that independently altered the risk of AKI. Results: The overall incidence of AKI in the study population was 6.3%. Using the minimum P -value approach, a threshold of 0.3 ml kg -1 h -1 was identified, below which there was an increased risk of AKI (adjusted odds ratio, 2.65; 95% confidence interval, 1.77-3.97; P <0.001). The addition of oliguria <0.3 ml kg -1 h -1 to a model with conventional risk factors significantly improved risk stratification for AKI (net reclassification improvement, 0.159; 95% confidence interval, 0.049-0.270; P =0.005). Conclusions: Among patients undergoing major abdominal surgery, intraoperative oliguria <0.3 ml kg -1 h -1 was significantly associated with increased risk of postoperative AKI.

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.

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.

Low urine output during the first twenty-four hours after total knee arthroplasty.

BACKGROUND: Low urine output (LUO) for six hours is defined as the stage that is at risk of acute renal failure. Major surgeries with a bloodless field, such as total knee arthroplasty (TKA), may be associated with LUO; however; there has been no study addressing this point. The present study evaluated the incidence of LUO and the effect of fluid balance on LUO in TKA patients during the first 24 hours after surgery. MATERIAL AND METHOD: The authors retrospectively evaluated 257 uncomplicated patients undergoing unilateral TKA during the first 24 hours after surgery. Patients' demographic data, intra-operative intravenous (IV) fluid replacement, postoperative IV fluid replacement, oral fluid intake, total fluid intake, postoperative urine output, blood collected from the drain, and the total visible fluid output during the first 24 hours after surgery were collected and evaluated. RESULTS: The incidence of LUO was 19.1% (49/257) in the studied group. There were no significant differences in patients' demographic data between the LUO and normal urine output (NUO) groups. Comparing the LUO and NUO groups, the LUO group had a lower volume of intra-operative fluid replacement, with statistical significance. There were no differences in postoperative IV fluid replacement and postoperative oral fluid intake between groups. Although 80.5% of the studied group had LV fluid replacement at a less than ideal level, at discharge there was no patient suffering from renal complications related to LUO. DISCUSSION AND CONCLUSION: Urine output is one of the common monitoring parameters of fluid balance in the perioperative period; it should be ≥ 0.5 mL/kg/h. Prolonged low urine output for six hours and for 12 hours are categorized as causing risk and injury to the kidney, respectively. The incidence of LUO at our institution during the first 24 hours after TKA is not uncommon and is significantly related to intra-operative fluid replacement. Fortunately, all LUO patients had further fluid replacement, resulting in no renal complications at discharge. As eighty percent of patients had less than ideal fluid replacement, and patients having LUO during the first 24 hours had a significantly lower volume of intra-operative fluid replacement, the authors propose reconsidering perioperative fluid replacement in TKA patients, especially intra-operative IV fluid to avoid LUO.

Failure of renal biomarkers to predict worsening renal function in high-risk patients presenting with oliguria.

PURPOSE: Oliguria is a common symptom in critically ill patients and puts patients in a high risk category for further worsening renal function (WRF). We performed this study to explore the predictive value of biomarkers to predict WRF in oliguric intensive care unit (ICU) patients. PATIENTS AND METHODS: Single-center prospective observational study. ICU patients were included when they presented a first episode of oliguria. Plasma and urine biomarkers were measured: plasma and urine neutrophil gelatinase-associated lipocalin (pNGAL and uNGAL), urine α1-microglobulin, urine γ-glutamyl transferase, urine indices of tubular function, cystatin C, C terminal fragment of pro-arginine vasopressin (CT-ProAVP), and proadrenomedullin (MR-ProADM). RESULTS: One hundred eleven patients formed the cohort, of whom 41 [corrected] had worsening renal function. Simplified Acute Physiology Score (SAPS) II was 41 (31-51). WRF was associated with increased mortality (hazard ratio 8.65 [95 % confidence interval (CI) 3.0-24.9], p = 0.0002). pNGAL, MR-ProADM, and cystatin C had the best odds ratio and area under the receiver-operating characteristic curve (AUC-ROC: 0.83 [0.75-0.9], 0.82 [0.71-0.91], and 0.83 [0.74-0.90]), but not different from serum creatinine (Screat, 0.80 [0.70-0.88]). A clinical model that included age, sepsis, SAPS II, and Screat had AUC-ROC of 0.79 [0.69-0.87]; inclusion of pNGAL increased the AUC-ROC to 0.86 (p = 0.03). The category-free net reclassification index improved with pNGAL (total net reclassification index for events to higher risk 61 % and nonevents to lower 82 %). CONCLUSIONS: All episodes of oliguria do not carry the same risk. No biomarker further improved prediction of WRF compared with Screat in this selected cohort of patients at increased risk defined by oliguria.

The influence of mean arterial blood pressure during cardiopulmonary bypass on postoperative renal dysfunction in elderly patients.

The aim of the study was to find out if there is an optimal mean arterial blood pressure (MABP) during cardiopulmonary bypass (CPB) for renal function in elderly patients during the early postoperative period. We analysed the data of 122 patients >70 years of age with normal preoperative renal function who had been subjected to coronary artery bypass grafting (CABG) procedures on CPB. Patients were divided into 3 groups, according to MABP during CPB: group MP (n=50) included patients whose MABP was maintained between 60-70 mmHg; group LP (n=36), the MABP was <60 mmHg; and group HP (n=36) where the MABP was >70 mmHg. The patients' clinical data were evaluated during the first three postoperative days. The rate of renal impairment (urine output <50ml/h) in the early postoperative period after cardiac surgery did not differ among the groups. Oliguria developed in 3 patients (6%) of the MP group, in 2 patients (5.6%) in the LP group and in 6 patients (16.7%) in the HP group (χ(2)=3.6, df=2, p=0.161). Evaluation of MABP on renal excretion showed that there was no difference in urine output among the groups. Serum creatinine levels at the end of the first postoperative day in groups MP, LP and HP were 102.7±20.1, 116.4±58.6 and 113.2±39.8 µmol/L, respectively (F=0.5, df=2, p=0.640). There were no significant differences among the groups at the end of the second and the third day either. Volume balance at the end of surgery and during the early postoperative period was similar in all groups. The need for diuretics did not differ among the groups. The length of postoperative hospital stay was not significantly different among the groups. Our study did not reveal any relationship between a MABP of 48-80 and postoperative renal dysfunction in elderly patients after CABG surgery.

Low-dose theophylline increases urine output in diuretic-dependent critically ill children.

OBJECTIVE: Determine the effect of low-dose theophylline on urine output and the urinary adenosine: cAMP (cyclic adenosine monophosphate) excretion ratio (a measure of phosphodiesterase inhibition) in diuretic-dependent critically ill children. DESIGN: Observational clinical case series and animal laboratory experiment. SETTING: A university pediatric intensive care unit and a pharmacology research laboratory. PATIENTS: 10 consecutive oliguric patients treated with theophylline for diuresis. INTERVENTIONS: Urine output, fluid intake, diuretic dosages, and number of pressors (including dopamine) were monitored over the 24-h period prior to and the 24-h period immediately after theophylline was started. Hourly collections of urine were obtained at baseline and 1 and 3 h after theophylline was started and urinary excretion rates of adenosine and cAMP were measured and calculated. MEASUREMENTS AND RESULTS: Mean theophylline level in the children was 5.0 microg/ml. Urine output increased from 1.58 +/- 0.46 to 3.75 +/- 0.77 ml/kg per h (p = 0.008, paired t-test) after theophylline administration. There was no significant change in fluid intake, vasoactive agents, or dosages of other diuretics during the study periods. Intrarenal infusion of the IC50 concentration of isobutylmethylxanthine for phosphodiesterase activity resulted in a reduction of the adenosine: cAMP urinary excretion ratio in rats (p < 0.05). Low-dose theophylline had no effect on the adenosine: cAMP urinary excretion ratio in children. Concurrent therapy with dopamine was associated with an enhanced diuretic effect of theophylline (with dopamine, 1.30 +/- 0.30 to 5.07 +/- 0.77 ml/kg per h vs without dopamine, 1.77 +/- 0.76 to 2.86 +/- 1.08 ml/kg per h; p = 0.03, two-way ANOVA). There was no interaction between dopamine and low-dose theophylline on the urinary adenosine: cAMP excretion ratio (p = 0.56, two-way ANOVA). CONCLUSIONS: Theophylline increased urine output in diuretic-dependent critically ill children and the diuretic effect may have been potentiated by concurrent use of dopamine. Adenosine receptor antagonism may be a more likely mechanism for the diuretic effect of theophylline than phosphodiesterase inhibition.