Predictors of oliguria in post-traumatic acute kidney injury.

BACKGROUND: Acute kidney injury is classified by urine output into non-oliguric and oliguric variants. Non-oliguric acute kidney injury has lower morbidity and mortality and accounts for up to 64% of acute kidney injury in hospitalized patients. However, the incidence of non-oliguric acute kidney injury in the trauma population and whether the 2 variants of acute kidney injury share the same risk factors is unknown. We hypothesized that oliguria would be present in the majority of acute kidney injury in severely injured trauma patients and that unique risk factors would predispose patients to the development of oliguria. METHODS: Patients admitted to the trauma intensive care unit and diagnosed with an acute kidney injury between 2016 to 2021 were identified. Cases were categorized based on urine output into oliguric (<400 mL per day) and non-oliguric (>400 mL per day) disease. Risk factors, management, and outcomes were compared. Logistic regression was used to identify risk factors associated with oliguria. RESULTS: A total of 227 patients met inclusion criteria. Non-oliguric acute kidney injury accounted for 74% of all cases and was associated with greater survival (78% vs 35.6%, P < .001). Using logistic regression, female sex, vasopressor use, and a greater net fluid balance at 48 hours were all predictive of oliguria (while controlling for age, race, shock index, massive transfusion, operative intervention, cardiac arrest, and nephrotoxic medication exposure). CONCLUSION: Non-oliguria accounts for the majority of post-traumatic acute kidney injury and is associated with improved survival. Specific risk factors for the development of oliguric acute kidney injury include female sex, vasopressor use, and a higher net fluid balance at 48 hours.

The role of Cushing's reflex and the vasopressin-mediated oligoanuric response to intracranial hypertension in patients with abdominal compartment syndrome.

BACKGROUND: We examined the link between increased intra-abdominal pressure, intracranial pressure, and vasopressin release as a potential mechanism. Intra-abdominal pressure, produced by abdominal-cavity insufflation with carbon dioxide (CO2) during laparoscopic abdominal procedures to facilitate visualization, is associated with various complications, including arterial hypertension and oliguria. METHODS: Mean arterial pressure, optic nerve sheath diameter, measured as a proxy for intracranial pressure, plasma vasopressin, serum and urine osmolarity, and urine output were measured 4 times during laparoscopic sleeve gastrectomy in 42 patients: before insufflation with CO2 (T0); after insufflation to 15 cm water (H2O) pressure, with 5 cm H2O positive end-expiratory pressure (T1); after positive end-expiratory pressure was raised to 10 cm H2O (T2); and after a return to the baseline state (T3). Mean values at T0 to T3 and the directional consistency of changes (increase/decrease/ unchanged) were compared among the 4 data-collection points. RESULTS: Statistically significant elevations (all P ≤ .001) were noted from T0 to T1 and from T0 to T2 in mean arterial pressure, optic nerve sheath diameter, and vasopressin, followed by decreases at T3. For optic nerve sheath diameter and vasopressin, the increases at T1 and T2 occurred in 98% and 100% of patients, ultimately exceeding normal levels in 88 and 97%, respectively. Conversely, urine output fell from T0 to T1 and T2 by 60.9 and 73.4%, decreasing in 88.1% of patients (all P < .001). Patients with class II obesity exhibited statistically greater increases in optic nerve sheath diameter and vasopressin, but statistically less impact on urine output, than patients with class III obesity. CONCLUSION: Increased mean arterial pressure, intracranial pressure, and vasopressin release appear to be intermediary steps between increased intra-abdominal pressure and oliguria. Further research is necessary to determine any causative links between these physiological changes.

Intraoperative hypotension, oliguria and operation time are associated with pulmonary embolism after radical resection of head and neck cancers: a case control study.

BACKGROUND: Postoperative pulmonary embolism (PE) is a serious thrombotic complication in the patients with otolaryngologic cancers. We investigated the risk factors associated with postoperative PE after radical resection of head and neck cancers. METHODS: A total of 3512 patients underwent head and neck cancers radical resection from 2013 to 2019. A one-to-three control group without postoperative PE was selected matched by age, gender, and type of cancer. Univariate analyses were performed for the perioperative patient data including hemodynamic management factors. Conditional logistic regression was used to analyze the factors and their odds ratios. RESULTS: Postoperative PE was prevalent in 0.85% (95%CI = 0.56-1.14). Univariate analyses showed that a high ASA grade, high BMI, and smoking history may be related to postoperative PE. There was significantly difference in operation time between the two groups, especially for> 4 h [22(78.6%) vs 43(51.2%), P = .011]. The urine output was lower [1.37(0.73-2.21) ml·kg- 1·h- 1 vs 2.14(1.32-3.46) ml·kg- 1·h- 1, P = .006] and the incidence of oliguria was significantly increased (14.3% vs 1.2%, P = .004) in the PE group. Multivariable conditional logistic regression showed postoperative PE were associated with the cumulative duration for intraoperative hypotension (OR = 2.330, 95%CI = 1.428-3.801, P = .001), oliguria (OR = 14.844, 95%CI = 1.089-202.249, P = .043), and operation time > 4 h (OR = 4.801, 95%CI = 1.054-21.866, P = .043). CONCLUSIONS: The intraoperative hypotension, oliguria, and operation time > 4 h are risk factors associated with postoperative PE after radical resection of head and neck cancers. Improving intraoperative hemodynamics management to ensure adequate blood pressure and urine output may reduce the occurrence of such complications.

Intraoperative oliguria does not predict postoperative acute kidney injury in major abdominal surgery: a cohort analysis / A oligúria intraoperatória não prediz lesão renal aguda pós-operatória em grandes cirurgias abdominais: Análise de uma coorte

Abstract Background: Acute kidney injury (AKI) is a common complication in patients undergoing major abdominal surgery and is associated with considerable morbidity and mortality. Several studies investigating the association between intraoperative urine output and postoperative AKI have shown conflicting results. Here, we investigated the association of intraoperative oliguria with postoperative AKI in a cohort of patients submitted to elective major abdominal surgery. Methods: This was a single-center retrospective analysis of adult patients who underwent elective major abdominal surgery from January 2016 to December 2018. AKI was defined according to the serum creatinine criteria of the KDIGO classification. Intraoperative oliguria was defined as urine output of less than 0.5 mL/kg/h. Risk factors were evaluated using multivariate logistic regression analysis. Results: A total of 165 patients were analyzed. In the first 48 h after surgery the incidence of AKI was 19.4%. Postoperative AKI was associated with hospital mortality (p=0.011). Twenty percent of patients developed intraoperative oliguria. There was no association between preexisting comorbidities and development of intraoperative oliguria. There was no correlation between the type of anesthesia used and occurrence of intraoperative oliguria, but longer anesthesia time was associated with intraoperative oliguria (p=0.007). Higher baseline SCr (p=0.001), need of vasoactive drugs (p=0.007), and NSAIDs use (p=0.022) were associated with development of intraoperative oliguria. Intraoperative oliguria was not associated with development of postoperative AKI (p=0.772), prolonged hospital stays (p=0.176) or in-hospital mortality (p=0.820). Conclusion: In this cohort of patients we demonstrated that intraoperative oliguria does not predict postoperative AKI in major abdominal surgery.

Resumo Introdução: Lesão renal aguda (LRA) é uma complicação comum em pacientes submetidos a grandes cirurgias abdominais, e está associada a considerável morbimortalidade. Vários estudos investigando a associação entre débito urinário intraoperatório e LRA pós-operatória mostraram resultados conflitantes. Neste trabalho investigamos a associação de oligúria intraoperatória com LRA pós-operatória em uma coorte de pacientes submetidos à grandes cirurgias abdominais. Métodos: Análise retrospectiva de centro único envolvendo pacientes adultos submetidos à grandes cirurgias abdominais, de janeiro de 2016 a dezembro de 2018. A LRA foi definida segundo critérios de creatinina da KDIGO. Definimos oligúria intraoperatória como débito urinário inferior a 0,5 mL/kg/h. Fatores de risco foram avaliados por análise de regressão logística multivariada. Resultados: Analisamos 165 pacientes. Nas primeiras 48 horas após a cirurgia, a incidência de LRA foi de 19,4%. LRA pós-operatória foi associada à mortalidade hospitalar (p = 0,011). 20% dos pacientes desenvolveram oligúria intraoperatória, sem associação com comorbidades preexistentes. Não houve correlação entre o tipo de anestesia e oligúria intraoperatória; entretanto, maior tempo de anestesia esteve associado à oligúria intraoperatória (p = 0,007). Maior creatinina sérica (Cr) inicial (p = 0,001), necessidade de drogas vasoativas (p = 0,007) e uso de AINEs (p = 0,022) foram associados à oligúria intraoperatória. Oligúria intraoperatória não foi associada ao desenvolvimento de LRA no pós-operatório (p = 0,772), à permanência hospitalar prolongada (p = 0,176) ou à mortalidade intra-hospitalar (p = 0,820). Conclusão: Demonstramos que a oligúria intraoperatória não prediz LRA pós-operatória em cirurgias abdominais de grande porte.

Clinical spectrum and predictors of severe Plasmodium vivax infections at a tertiary care center in North India.

Traditionally attributed only to Plasmodium falciparum, Plasmodium vivax has recently been reported to cause a significant burden of complicated malaria cases. The present study aimed to delineate the clinical spectrum and identify predictors for severe disease. This was a prospective observational cohort study conducted at a tertiary care hospital in North India. Patients with acute febrile illness (AFI) aged at least 14 years were included if they were diagnosed with vivax malaria based on rapid kits or peripheral smears. Clinical data and investigations during hospital stay was recorded. 439 cases of acute febrile illness were screened, of whom 50 (11%) were diagnosed with malaria including eight P. falciparum infections. Forty-two vivax malaria cases, 22 (52%) of whom were severe, were followed till discharge or death. The median age of the cohort was 24.5 years (Q1-Q3, 19-36 years), including a total of 29 males (69%). Severe malaria was more frequently associated with historical complaints of oliguria or dyspnea, and examination findings of pallor, splenomegaly or altered sensorium. The following five factors were identified to predict severe disease: prolonged illness over 7 days, symptoms of oliguria or dyspnea, examination findings of pallor or crepitations on auscultation. Malaria accounts for 1 in 10 cases of AFI at our North Indian tertiary care center and approximately half of them present with severe disease. Prolonged duration of disease prior to presentation is a modifiable predictor for severe disease and should be targeted for reducing morbidity.

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.

Intraoperative oliguria does not predict postoperative acute kidney injury in major abdominal surgery: a cohort analysis.

BACKGROUND: Acute kidney injury (AKI) is a common complication in patients undergoing major abdominal surgery and is associated with considerable morbidity and mortality. Several studies investigating the association between intraoperative urine output and postoperative AKI have shown conflicting results. Here, we investigated the association of intraoperative oliguria with postoperative AKI in a cohort of patients submitted to elective major abdominal surgery. METHODS: This was a single-center retrospective analysis of adult patients who underwent elective major abdominal surgery from January 2016 to December 2018. AKI was defined according to the serum creatinine criteria of the KDIGO classification. Intraoperative oliguria was defined as urine output of less than 0.5 mL/kg/h. Risk factors were evaluated using multivariate logistic regression analysis. RESULTS: A total of 165 patients were analyzed. In the first 48 h after surgery the incidence of AKI was 19.4%. Postoperative AKI was associated with hospital mortality (p=0.011). Twenty percent of patients developed intraoperative oliguria. There was no association between preexisting comorbidities and development of intraoperative oliguria. There was no correlation between the type of anesthesia used and occurrence of intraoperative oliguria, but longer anesthesia time was associated with intraoperative oliguria (p=0.007). Higher baseline SCr (p=0.001), need of vasoactive drugs (p=0.007), and NSAIDs use (p=0.022) were associated with development of intraoperative oliguria. Intraoperative oliguria was not associated with development of postoperative AKI (p=0.772), prolonged hospital stays (p=0.176) or in-hospital mortality (p=0.820). CONCLUSION: In this cohort of patients we demonstrated that intraoperative oliguria does not predict postoperative AKI in major abdominal surgery.

A Novel Patient-Specific Model for Predicting Severe Oliguria; Development and Comparison With Kidney Disease: Improving Global Outcomes Acute Kidney Injury Classification.

OBJECTIVES: The Kidney Disease: Improving Global Outcomes urine output criteria for acute kidney injury lack specificity for identifying patients at risk of adverse renal outcomes. The objective was to develop a model that analyses hourly urine output values in real time to identify those at risk of developing severe oliguria. DESIGN: This was a retrospective cohort study utilizing prospectively collected data. SETTING: A cardiac ICU in the United Kingdom. PATIENTS: Patients undergoing cardiac surgery between January 2013 and November 2017. INTERVENTIONS: None. MEASUREMENT AND MAIN RESULTS: Patients were randomly assigned to development (n = 981) and validation (n = 2,389) datasets. A patient-specific, dynamic Bayesian model was developed to predict future urine output on an hourly basis. Model discrimination and calibration for predicting severe oliguria (< 0.3 mL/kg/hr for 6 hr) occurring within the next 12 hours were tested in the validation dataset at multiple time points. Patients with a high risk of severe oliguria (p > 0.8) were identified and their outcomes were compared with those for low-risk patients and for patients who met the Kidney Disease: Improving Global Outcomes urine output criterion for acute kidney injury. Model discrimination was excellent at all time points (area under the curve > 0.9 for all). Calibration of the model's predictions was also excellent. After adjustment using multivariable logistic regression, patients in the high-risk group were more likely to require renal replacement therapy (odds ratio, 10.4; 95% CI, 5.9-18.1), suffer prolonged hospital stay (odds ratio, 4.4; 95% CI, 3.0-6.4), and die in hospital (odds ratio, 6.4; 95% CI, 2.8-14.0) (p < 0.001 for all). Outcomes for those identified as high risk by the model were significantly worse than for patients who met the Kidney Disease: Improving Global Outcomes urine output criterion. CONCLUSIONS: This novel, patient-specific model identifies patients at increased risk of severe oliguria. Classification according to model predictions outperformed the Kidney Disease: Improving Global Outcomes urine output criterion. As the new model identifies patients at risk before severe oliguria develops it could potentially facilitate intervention to improve patient outcomes.

[Impact of oliguria during lung surgery on postoperative acute kidney injury].

OBJECTIVE: To explore the influence of intraoperative urine volume on postoperative acute kidney injury (AKI) and the independent risk factors of AKI. METHODS: This was a retrospective cohort study recruiting patients who received selective pulmonary resection under general anesthesia in Peking University First Hospital from July, 2017 to June, 2019. The patients were divided into the AKI group and the control group according to whether they developed postoperative AKI or not. Firstly, univariate analysis was used to analyze the relationship between perioperative variables and postoperative AKI. Secondly, receiver operating characteristic (ROC) curve was used to explore the predictive value of intraoperative urine output for postoperative AKI. The nearest four cutoff values [with the interval of 0.1 mL/(kg·h)] at maximum Youden index were used as cutoff values of oliguria. Then univariate analysis was used to explore the relationship between oliguria defined by these four cutoff values and the risk of AKI. And the cutoff value with maximum OR was chosen as the threshold of oliguria in this study. Lastly, the variables with P < 0.10 in the univariate analysis were selected for inclusion in a multivariate Logistic model to analyze the independent predictors of postoperative AKI. RESULTS: A total of 1 393 patients were enrolled in the study. The incidence of postoperative AKI was 2.2%. ROC curve analysis showed that the area under curve (AUC) of intraoperative urine volume used for predicting postoperative AKI was 0.636 (P=0.009), and the cutoff value of oliguria was 0.785 mL/(kg·h) when Youden index was maximum (Youden index =0.234, sensitivity =48.4%, specificity =75.0%). Furthermore, 0.7, 0.8, 0.9, 1.0 mL/(kg·h) and the traditional cutoff value of 0.5 mL/(kg·h) were used to analyze the influence of oliguria on postoperative AKI. Univariate analysis showed that, when 0.8 mL/(kg·h) was selected as the threshold of oliguria, the patients with oliguria had the most significantly increased risk of AKI (AKI group 48.4% vs. control group 25.3%, OR=2.774, 95%CI 1.357－5.671, P=0.004). Multivariate regression analysis showed that intraoperative urine output < 0.8 mL/(kg·h) was one of the independent risk factors of postoperative AKI (OR=2.698, 95%CI 1.260－5.778, P=0.011). The other two were preoperative hemoglobin ≤120.0 g/L (OR=3.605, 95%CI 1.545－8.412, P=0.003) and preoperative estimated glomerular filtration rate < 30 mL/(min·1.73 m2) (OR=11.009, 95%CI 1.813－66.843, P=0.009). CONCLUSION: Oliguria is an independent risk fact or of postoperative AKI after pulmonary resection, and urine volume < 0.8 mL/(kg·h) is a possible screening criterium.

Characteristics of nonoliguric hyperkalemia in preterm infants: A case-control study in a single center.

BACKGROUND: Preterm infants often present with hyperkalemia during the first days after birth without showing oliguria. This is known as nonoliguric hyperkalemia (NOHK). As its clinical features have not been completely understood to date, we aimed to elucidate the characteristics of NOHK, including its risk factors, in preterm infants. METHODS: For this case-control study, we reviewed the files of all infants born before 32 weeks of gestational age in our neonatal intensive care unit between 2011 and 2018. We distinguished the NOHK and non-NOHK groups and compared their characteristics and blood potassium levels. Nonoliguric hyperkalemia was defined as peak blood potassium concentration of ≥6.0 mmol/L during the first 72 h of life with a urine output of ≥1 mL/kg/h. RESULTS: Of the 99 infants enrolled, 21 (21%) demonstrated NOHK. Infants with NOHK were more likely to have been exposed to antenatal magnesium sulfate (MgSO4 ) (P = 0.019) than those in the non-NOHK group. Acute morbidities and mortality were not statistically different. Multivariate analysis indicated that administration of maternal MgSO4 for longer than 24 h at any point before delivery was a risk factor for NOHK. Its adjusted odds ratio and 95% confidence interval were 4.0 and 1.4-12.3, respectively (P = 0.012). CONCLUSIONS: In this study, maternal MgSO4 administration for longer than 24 h proved to be a risk factor for NOHK in infants born before 32 weeks of gestational age. Infants born to mothers who have received MgSO4 should be regularly monitored for their electrolytes.

Importance of intraoperative oliguria during major abdominal surgery: findings of the Restrictive versus Liberal Fluid Therapy in Major Abdominal Surgery trial.

BACKGROUND: The association between intraoperative oliguria during major abdominal surgery and the subsequent development of postoperative acute kidney injury (AKI) remains poorly defined. We hypothesised that, in such patients, intraoperative oliguria would be an independent predictor of subsequent AKI. METHODS: We performed a post hoc analysis of data from the Restrictive versus Liberal Fluid Therapy in Major Abdominal Surgery (RELIEF) trial of conservative vs liberal fluid therapy during and after major abdominal surgery. We used χ2, logistic regression, and fractional polynomials to study the association between intraoperative oliguria defined as a urinary output <0.5 ml kg-1 h-1 and the development of postoperative AKI defined by the Kidney Disease Improving Global Outcomes consensus criteria. RESULTS: We included 2444 of 2983 patients from the RELIEF trial in this study. A total of 889 patients (36%) met oliguric criteria intraoperatively. Oliguria occurred in 35% of those without AKI, and 44%, 48%, and 45% of those who developed postoperative AKI Stages 1-3, respectively (P<0.001 for trend). Intraoperative oliguria was associated with an increased risk of AKI, risk ratio: 1.38 (95% confidence interval: 1.14-1.44; P<0.001), but greater intensity of oliguria (urine output <0.3 ml kg-1 h-1) did not increase this risk further. Most patients with oliguria did not develop AKI; the positive predictive value of oliguria was 25.5%, and the negative predictive value was 81.6%. CONCLUSIONS: Intraoperative oliguria, defined as urine output <0.5 ml kg-1 h-1, was relatively common and was associated with postoperative AKI. However, the predictive utility of oliguria for AKI was low, whilst its absence had a good predictive value for an AKI-free postoperative course. CLINICAL TRIAL REGISTRATION: NCT01424150.

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.

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.

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.

Influenza-associated thrombotic microangiopathies.

Thrombotic microangiopathy (TMA) refers to phenotypically similar disorders, including hemolytic uremic syndromes (HUS) and thrombotic thrombocytopenic purpura (TTP). This review explores the role of the influenza virus as trigger of HUS or TTP. We conducted a literature survey in PubMed and Google Scholar using HUS, TTP, TMA, and influenza as keywords, and extracted and analyzed reported epidemiological and clinical data. We identified 25 cases of influenza-associated TMA. Five additional cases were linked to influenza vaccination and analyzed separately. Influenza A was found in 83%, 10 out of 25 during the 2009 A(H1N1) pandemic. Two patients had bona fide TTP with ADAMTS13 activity <10%. Median age was 15 years (range 0.5-68 years), two thirds were male. Oligoanuria was documented in 81% and neurological involvement in 40% of patients. Serum C3 was reduced in 5 out of 14 patients (36%); Coombs test was negative in 7 out of 7 and elevated fibrin/fibrinogen degradation products were documented in 6 out of 8 patients. Pathogenic complement gene mutations were found in 7 out of 8 patients tested (C3, MCP, or MCP combined with CFB or clusterin). Twenty out of 24 patients recovered completely, but 3 died (12%). Ten of the surviving patients underwent plasma exchange (PLEX) therapy, 5 plasma infusions. Influenza-mediated HUS or TTP is rare. A sizable proportion of tested patients demonstrated mutations associated with alternative pathway of complement dysregulation that was uncovered by this infection. Further research is warranted targeting the roles of viral neuraminidase, enhanced virus-induced complement activation and/or ADAMTS13 antibodies, and rational treatment approaches.

Low cardiac output syndrome in the postoperative period of cardiac surgery. Profile, differences in clinical course and prognosis. The ESBAGA study. / Síndrome de bajo gasto cardiaco en el postoperatorio de cirugía cardiaca. Perfil, diferencias en evolución clínica y pronóstico. Estudio ESBAGA.

OBJECTIVES: An analysis is made of the clinical profile, evolution and differences in morbidity and mortality of low cardiac output syndrome (LCOS) in the postoperative period of cardiac surgery, according to the 3 diagnostic subgroups defined by the SEMICYUC Consensus 2012. DESIGN: A multicenter, prospective cohort study was carried out. SETTING: ICUs of Spanish hospitals with cardiac surgery. PATIENTS: A consecutive sample of 2,070 cardiac surgery patients was included, with the analysis of 137 patients with LCOS. INTERVENTIONS: No intervention was carried out. RESULTS: The mean patient age was 68.3±9.3 years (65.2% males), with a EuroSCORE II of 9.99±13. NYHA functional class III-IV (52.9%), left ventricular ejection fraction<35% (33.6%), AMI (31.9%), severe PHT (21.7%), critical preoperative condition (18.8%), prior cardiac surgery (18.1%), PTCA/stent placement (16.7%). According to subgroups, 46 patients fulfilled hemodynamic criteria of LCOS (group A), 50 clinical criteria (group B), and the rest (n=41) presented cardiogenic shock (group C). Significant differences were observed over the evolutive course between the subgroups in terms of time subjected to mechanical ventilation (114.4, 135.4 and 180.3min in groups A, B and C, respectively; P<.001), renal replacement requirements (11.4, 14.6 and 36.6%; P=.007), multiorgan failure (16.7, 13 and 47.5%), and mortality (13.6, 12.5 and 35.9%; P=.01). The mean maximum lactate concentration was higher in cardiogenic shock patients (P=.002). CONCLUSIONS: The clinical evolution of these patients leads to high morbidity and mortality. We found differences between the subgroups in terms of the postoperative clinical course and mortality.

Renal function in neonates with twin-twin transfusion syndrome treated with or without fetoscopic laser surgery.

The aim of this study is to investigate the short-term renal function in neonates with twin-twin transfusion syndrome (TTTS), treated with fetoscopic laser surgery (laser group) or conservatively (non-laser group). Creatinine and urea levels and urine output were recorded in the first week after birth. Primary outcome was short-term renal dysfunction, defined as a creatinine level of >100 µmol/L during the first week postpartum. We evaluated 312 twins (laser group, n = 274; non-laser group, n = 38). Median creatinine and urea levels were lower in the laser group than in the non-laser group (71 versus 82 µmol/L, p = 0.002). Short-term renal dysfunction was lower in the laser group compared to the non-laser group (7.2 versus 34.4%, p < 0.001). Within the laser group, creatinine levels were significantly higher in the subgroup with incomplete laser surgery compared to twins with successful laser surgery (76 versus 69 µmol/L, p = 0.018). No differences were found between donors and recipients except for a higher incidence of oliguria in donors in the non-laser group on day 1. CONCLUSION: Short-term renal dysfunction occurs less frequently in TTTS twins treated with fetoscopic laser coagulation, particularly after complete surgery, suggesting that laser surgery may have a protective effect on renal function. What is Known: • Antenatally, donor twins in TTTS have severe oliguria due to chronic hypovolemia and impaired renal perfusion • Postnatally, donor twins may suffer from severe renal complications, particularly in TTTS twins treated conservatively. What is New: • The incidence of short-term renal failure in TTTS twins treated with complete laser surgery is low. • After incomplete laser surgery, the incidence of short-term renal dysfunction is increased.

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.

Influence of caudal block on postoperative oliguria in infants undergoing bilateral ureteroneocystostomy: a retrospective analysis.

BACKGROUND: Caudal block has been widely used in children undergoing genitourinary surgery. However, the influence of caudal block on postoperative oliguria is unclear. AIM: The aim of this study was to assess the effect of caudal block on urinary flow through the reimplanted ureter after ureteroneocystostomy and the incidence of postoperative oliguria in infants. METHODS: This retrospective study analyzed the medical records of 121 infants aged less than 12 months who underwent bilateral ureteroneocystostomy for vesicoureteral reflux at a tertiary medical center. In all study infants, a ureteral catheter was placed in one of the two ureters in order to relieve the clinical consequences of transient ureteral obstruction and a urethral catheter was placed at the end of the ureteroneocystostomy procedure. Urinary output was assessed separately for each catheter. Logistic regression analysis was performed to identify the risk factors for oliguria from the urethral catheter. RESULTS: Among the 121 patients, 63 (52%) received caudal block (caudal block group) and 58 (48%) did not (no caudal block group). Patient characteristics, preoperative vesicoureteral reflux grade and renal function, and intraoperative profiles were comparable between the groups. The incidence of oliguria from the urethral catheter for 8 h after the surgery was significantly higher in the caudal block group than in the no caudal block group. However, the incidence of oliguria from the ureteral catheter was comparable between the groups. In multivariate analysis, oliguria from the urethral catheter was associated with caudal block, anesthesia duration, and intraoperative dexamethasone administration. The odds for oliguria was 3.069-fold greater in patients who received caudal block than in those who did not (95%CI, 1.303-7.228, P = 0.010). On the other hand, intraoperative dexamethasone reduced the risk of oliguria. CONCLUSION: Caudal block may be associated with postoperative oliguria in infants undergoing ureteroneocystostomy.

Earlier nephrology consultation may not be associated with improved short-term survival of acute kidney injury in very elderly men.

OBJECTIVES: A delayed nephrology consultation (NC) may be associated with a poor prognosis in acute kidney injury (AKI) patients. The aims of this study were to compare the clinical and laboratory characteristics of elderly AKI patients evaluated and not evaluated by nephrologists and to generate a hypothesis regarding the relationship between the timing of the NC and 90-day outcomes. METHODS: From 2007 to 2015, this study explored associations among the presence and timing of NC with the non-intensive care unit stay and 90-day mortality in elderly AKI patients at the Geriatric Department of the Chinese People's Liberation Army General Hospital. Early NC and delayed NC were defined as NCs performed before and 2 days after the day of AKI diagnosis, respectively. Multivariable logistic regression was used to adjust for confounding and selection bias. RESULTS: In total, 623 patients were included for the final analysis, of whom 162 (26%) were evaluated by nephrologists. The 90-day mortality rate was 33.2%, and dialysis was required in 1.4% of patients (9/623). Multivariable analysis showed that a higher prevalence of preexisting chronic obstructive pulmonary disease, AKI diagnosis time, peak serum creatinine level, blood urea nitrogen level, AKI stage, and mortality was associated with the NC. The NC was delayed (>48 h) in 59 patients (36.4%) (median time to consultation, 4 days). The median AKI diagnosis time, presence of oliguria, uric acid level, and a more severe AKI stage were associated with delayed consultation. Moreover, delayed consultation presented a similar 90-day mortality rate to that of an early NC (50.8% vs 44.7%, respectively, P=0.448). CONCLUSION: In very elderly AKI patients, those evaluated by nephrologists have more severe AKI and a higher mortality rate than those not evaluated by nephrologists. An earlier NC may not be associated with improved 90-day survival.