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.

Nephroprotective Effect of EDL Peptide at Acute Injury of Kidneys of Different Genesis.

EDL peptide produced a nephroprotective effect on experimental models gentamycin-induced nephropathy and ischemia/reperfusion kidney injury in rats. The nephroprotective effect of EDL peptide manifested in prevention of oliguria and retention azotemia, a decrease in proteinuria and sodium excretion, prevention of critical decrease in activities of antioxidant enzymes, suppression of LPO, and normalization of energy supply to kidneys cells. Our findings confirm the prospects of further studies of the nephroprotective properties of peptide EDL in various pathologies of the kidneys.

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.

Effect of the volume of fluids administered on intraoperative oliguria in laparoscopic bariatric surgery: a randomized controlled trial.

OBJECTIVE: To determine whether intraoperative fluid management affects urine output in patients undergoing laparoscopic bariatric operations. DESIGN: Randomized controlled trial. SETTING: Academic tertiary referral center. PATIENTS: Morbidly obese patients scheduled to undergo laparoscopic bariatric procedures. INTERVENTIONS: Patients were randomly assigned to receive intraoperatively high (10 mL/kg/h, n = 55) or low (4 mL/kg/h, n = 52) amounts of Ringer lactate solution. MAIN OUTCOME MEASURES: The primary end point was urine output. Secondary end points were postoperative creatinine serum concentration and complication rate. RESULTS: Significantly more fluids were administered intraoperatively to patients in the high-volume group compared with the low-volume group (P < .001). Regardless of the amount of fluids administered intraoperatively, low urine outputs (median [range], 100 [15-1050] mL in the high-volume group vs 107 [25-500] mL in the low-volume group; P = .34) were documented and were not significantly different. The mean creatinine serum concentration was within normal range at all times and was not significantly different between the groups (P = .68). The number of patients with complications was nonsignificantly lower in the low-volume group compared with the high-volume group (7 vs 10 patients, respectively; P = .60). CONCLUSIONS: In patients undergoing laparoscopic bariatric surgery, intraoperative urine output is low regardless of the use of relatively high-volume fluid therapy. The results suggest that we should reconsider the common practice to administer intraoperative fluids in response to low urine output. Further studies are required to evaluate these data in other surgical patient populations. Trial Registration  clinicaltrials.gov Identifier: NCT00753402.

Early volume expansion during diarrhea and relative nephroprotection during subsequent hemolytic uremic syndrome.

OBJECTIVES: To determine if interventions during the pre-hemolytic uremic syndrome (HUS) diarrhea phase are associated with maintenance of urine output during HUS. DESIGN: Prospective observational cohort study. SETTINGS: Eleven pediatric hospitals in the United States and Scotland. PARTICIPANTS: Children younger than 18 years with diarrhea-associated HUS (hematocrit level <30% with smear evidence of intravascular erythrocyte destruction), thrombocytopenia (platelet count <150 × 10³/mm³), and impaired renal function (serum creatinine concentration > upper limit of reference range for age). INTERVENTIONS: Intravenous fluid was given within the first 4 days of the onset of diarrhea. OUTCOME MEASURE: Presence or absence of oligoanuria (urine output ≤ 0.5 mL/kg/h for >1 day). RESULTS: The overall oligoanuric rate of the 50 participants was 68%, but was 84% among those who received no intravenous fluids in the first 4 days of illness. The relative risk of oligoanuria when fluids were not given in this interval was 1.6 (95% confidence interval, 1.1-2.4; P = .02). Children with oligoanuric HUS were given less total intravenous fluid (r = -0.32; P = .02) and sodium (r = -0.27; P = .05) in the first 4 days of illness than those without oligoanuria. In multivariable analysis, the most significant covariate was volume infused, but volume and sodium strongly covaried. CONCLUSIONS: Intravenous volume expansion is an underused intervention that could decrease the frequency of oligoanuric renal failure in patients at risk of HUS.

Semiología renal y genitourinaria en pediatría: primera parte / Nephrologoy and urology semiology in children: first part

A pesar de los avances tecnológicos, la historia clínica y el examen físico continúan y continuarán siendo la base de un buen enfoque y aproximación diagnóstica correcta, por ésto, la semiología sigue siendo un área muy importante en la medicina. En ésta revisión se plantea una guía sistemática e integral para la evaluación del sistema nefro-urológico en el niño desde las herramienta básicas y fundamentales como la historia clínica, el examen físico con sus componentessemiológicos en lo normal y lo patológico, integrando además los métodos diagnósticos de laboratorio e imagen disponibles en la actualidad, para lograr un buen enfoque y aproximación diagnóstica en niños con enfermedad renal.

Despite technological advances, medical history and physical examination remain the foundation of a good approach and correct diagnosis; semiology remains a very important area in medicine. In this review a systematic and comprehensive guide for the evaluation of nephron urological system in children is presented, with emphasis in medical history, physical examination and semiotic aspects, in normal and pathological conditions; additionally laboratory and imaging studies available to achieve a good diagnostic approach in children with renal disease are presented.

A previously undescribed etiology for oliguria in a premature infant with a peripherally inserted central catheter.

Peripherally inserted central catheter use has become widespread in the management of premature infants as a means to provide long-term intravenous therapy and nutritional support until enteral feedings can be established. Peripherally inserted central catheters are not without complications. This article describes the case of a premature infant with oliguria with the suspected etiology of a malpositioned catheter tip at a location where it was either occluding/blocking the renal vein(s) or causing damage to the kidney(s) from administration of hypertonic total parenteral nutrition solution directly into the renal vein(s). Peripherally inserted central catheter position should be verified radiographically and evaluated serially in any infant, even more so in an infant with symptoms of oliguria and possible sepsis.

Post-resuscitation strategies to avoid ongoing injury following intrapartum hypoxia-ischemia.

The interruption of placental blood flow during labor with redistribution of cardiac output resulting in increased flow to brain, heart, and adrenal glands at the expense of flow to kidney, gut, and skin can result in systemic organ as well as cerebral injury. Thus, post-resuscitation strategies should focus on both the management of potential systemic organ dysfunction and on methods of preventing ongoing brain injury in high-risk infants. General management strategies should include ventilator management to maintain pCO(2) values in the normal range, close attention to blood pressure to avoid hypotension, striving to avoid hypoglycemia, and control of seizures. Modest hypothermia administered within the first 6 hours has been shown to reduce neurodevelopmental deficits and death in those infants at highest-risk infants for developing hypoxic-ischemic brain injury.

Oliguria during corrective spinal surgery for idiopathic scoliosis: the role of antidiuretic hormone.

Patients undergoing surgery for idiopathic scoliosis were studied to determine the incidence and aetiology of oliguria during the perioperative period and to evaluate the efficacy of low dose dopamine in preventing its occurrence. Thirty patients, aged 6-18 years undergoing elective surgery were studied. Anaesthesia was standardized. Patients were randomized to receive either dopamine infusion (3 micrograms.kg-1.min-1) (Group A) (n = 15) or dextrose infusion (control) (Group B) (n = 15). Serum and urinary electrolytes and osmolalities and serum antidiuretic hormone (ADH) concentrations were measured. Urine output and haemodynamic parameters were recorded. Intraoperative oliguria occurred in 7% of patients in Group A and 47% in Group B (P < 0.05). Postoperative oliguria occurred in 20% of patients in Group A and 47% in Group B (P > 0.05). Urine and serum biochemical analysis revealed a statistically significant decrease in serum sodium and osmolality (P < 0.005) and an increase in urinary sodium and osmolality in both groups. Serum ADH concentrations were increased in both groups (P < 0.05), returning to baseline 18 h postoperatively. We conclude that oliguria during corrective spinal surgery occurs in association with excess ADH secretion as opposed to perioperative hypovolaemia. Dopamine increases urine output in the perioperative period but does not prevent the release of ADH and its subsequent biochemical effects.

A prospective randomized evaluation of the prophylactic use of low-dose dopamine in cancer patients receiving interleukin-2.

The administration of high-dose interleukin-2 (IL-2) causes tumor regression in 17-25% of patients with metastatic melanoma or renal cell carcinoma. Renal dysfunction is a common dose-limiting toxicity of IL-2 administration, limiting 26% of treatment cycles. We have conducted a prospective randomized trial to evaluate whether the prophylactic administration of low-dose dopamine (2 mg/kg/min) can minimize renal toxicity and thus affect the amount of IL-2 administered. Forty-two patients were randomly assigned to receive systemic high-dose IL-2 with standard supportive measures (group A = 21 patients) or with the addition of prophylactic dopamine (group B = 21 patients) at 2 mg/kg/min. For patients in group B, dopamine was instituted 1 h before the initiation of IL-2 administration and was discontinued 6-12 h after the maximum number of doses of IL-2 were given. There was no difference in the amount of IL-2 administered for each course of therapy for groups A and B. Despite differences in urine flow (milliliters per kilogram per day), fluid balance (liters per day), and overall weight gain, prophylactic low-dose dopamine did not significantly alter maximum plasma urea or creatinine levels in group B when compared with the control group (group A). The overall toxicity profile considering all grade 3 and 4 toxicities for patients in groups A and B was comparable. Thus, there is no evidence to support the routine use of prophylactic low-dose dopamine in patients receiving high-dose IL-2.

The effect of prolonged pneumoperitoneum on renal function in an animal model.

BACKGROUND: Prolonged, increased intra-abdominal pressure (IAP) during laparoscopic surgery has been associated with oliguria and anuria. STUDY DESIGN: The objective of this study was to evaluate the effects of various levels of IAP on renal function. Ten groups of three adult female farm pigs were given a general anesthetic, followed by establishment of an IAP of 0, 5, 10, 15, or 20 mm Hg with CO2, 20 mm Hg with argon gas, abdominal wall lift device, renal vein occlusion (RVO), 15 mm Hg with CO2 plus dopamine administration at 2 microgram/kg/minute, or 20 mm Hg retroperitoneal CO2 insufflation. The following studies were recorded: baseline central venous pressure (CVP), pulmonary wedge pressure (PWP), cardiac output (CO), renal vein flow (RVF), renal artery pressure (RAP), selective urine output (UO), urinary osmolarity, and creatinine clearance; the parameters were repeated every 30 minutes for the four hours of the IAP study and two hours after release of the IAP. RESULTS: The results were analyzed within two main IAP groups: less than 15 mm Hg and greater than or equal to 15 mm Hg. There was no clinically significant variation in the CVP, PWP, and RAP. The CO decreased slightly and this was more significant in the greater than or equal to 15 mm Hg group. The RVF and UO decreased concomitantly and significantly in the greater than or equal to 15 mm Hg group. Even after two hours of desufflation, the RVF did not return to baseline, although the UO improved. Creatinine clearance decreased significantly in the greater than or equal to 15 mm Hg group. The RVO group exhibited similar changes in the study parameters as those seen in the greater than or equal to 15 mm Hg group, although the RVF did not improve on release of the renal vein in the RVO group. Changes were the same with an argon or CO2 IAP of 20 mm Hg. The abdominal wall lift device had an associated decrease in RVF at 15 KG force but no alteration in UO. Retroperitoneal insufflation resulted in the same decrease in RVF and UO as seen with the same IAP. Dopamine did not afford a protective effect on UO during an IAP of 15 mm Hg. CONCLUSIONS: The decreased UO during prolonged IAP greater than or equal to 15 mm Hg in the animal model is associated with a corresponding decrease in RVF, but does not appear to be associated with any permanent renal derangement nor any transient histologic changes.

[New approaches to the pathogenetic therapy and prevention of acute kidney failure related to the use of x-ray contrast agents]. / Novye podkhody k patogeneticheskoi terapii i profilaktike ostroi pochechnoi nedostatochnosti, sviazannoi s primeneniem rentgenokontrastnykh sredstv.

The authors analyze causes, mechanisms underlying acute renal failure (ARF) attributed to tests with application of radioopaque substances and results of ARF treatment in 12 ARF patients and on Wistar rats models. It is inferred that ARF is a frequent and severe complication of the above tests which may be treated successfully by early application of dialysis, filtration, sorption, plasmapheresis techniques. Disorders of calcium metabolism and their correction contribute to ARF onset. Radio-opaque substances have essential inhibiting action on nitrogen oxide synthesis in the kidneys of experimental animals.

Verapamil prevents post-transplant oliguric renal failure.

Verapamil has proven effective in preventing acute renal failure in animal models if given prior to the insult and hence possibly has a role in the preservation of cadaveric renal tissue for transplantation. Twenty renal donors were randomly assigned to treatment (receiving verapamil 20 mg intravenously) and control groups. Recipients were monitored for renal failure by urine output and serum creatinines on days 1 and 7 and dialysis requirement to one week. Early urine outputs and serum creatinines (day 1) were significantly better in the treated than control group (p greater than 0.01, 0.05 respectively). We conclude therefore that verapamil may prevent post-transplant acute renal failure, but its optimal dosage and route of administration remain to be determined.