Contrast-induced acute kidney injury:A review of practical points

Contrast-induced acute kidney injury(CI-AKI) is oneof the most common causes of AKI in clinical practice.CI-AKI has been found to be strongly associated with morbidity and mortality of the patients.Furthermore,CI-AKI may not be always reversible and it may be associated with the development of chronic kidney disease.Pathophysiology of CI-AKI is not exactly understood and there is no consensus on the preventive strategies.CI-AKI is an active research area thus clinicians should be updated periodically about this topic.In this review,we aimed to discuss the indications of contrastenhanced imaging,types of contrast media and their impact on nephrotoxicity,major pathophysiological mechanisms,risk factors and preventive strategies of CI-AKI and alternative non-contrast-enhanced imaging methods.

Biochemical metabolic changes assessed by ^(31)P magnetic resonance spectroscopy after radiation-induced hepatic injury in rabbits

AIM： To compare the features of biochemical metabolic changes detected by hepatic phosphorus-31 magnetic resonance spectroscopy （^31p MRS） with the liver damage score （LDS） and pathologic changes in rabbits and to investigate the diagnostic value of ^31p MRS in acute hepatic radiation injury. METHODS： A total of 30 rabbits received different radiation doses （ranging 5-20 Gy） to establish acute hepatic injury models. Blood biochemical tests, ^31p MRS and pathological examinations were carried out 24 h after irradiation. The degree of injury was evaluated according to LD5 and pathology. Ten healthy rabbits served as controls. The MR examination was performed on a 1.5 T imager using a 1H/^31P surface coil by the 2D chemical shift imaging technique. The relative quantities of phosphomonoesters （PME）, phosphodiesters （PDE）, inorganic phosphate （Pi） and adenosine triphosphate （ATP） were measured. The data were statistically analyzed. RESULTS： （1） Relative quantification of phosphorus metabolites： （a） ATP： there were significant differences （P 〈 0.05） （LDS-groups：control group vs mild group vs moderate group vs severe group, 1.83±0.33 vs 1.55±0.24 vs 1.27±0.09 vs 0.98±0.18; pathological groups： control group vs mild group vs moderate group vs severe group, 1.83±0.33 vs 1.58±0.25 vs 1.32±0.07 vs 1.02±0.18） of ATP relative quantification among control group, mild injured group, moderate injured group, and severe injured group according to both LDS grading and pathological grading, respectively, and it decreased progressively with the increased degree of injury （r = -0.723, P = 0.000）. （b） PME and Pi; the relative quantification of PME and Pi decreased significantly in the severe injured group, and the difference between the control group and severe injured group was significant （P 〈 0.05） （PME： 1DS- control group vs LDS-severe group, 0.86±0.23 vs 0.58±0.22, P = 0.031; pathological control group vs pathological severe group, 0.86±0.23 vs 0.60±0.21, P = 0.037; Pi： LDS-control group vs LDS-severe group, 0.74±0.18 vs 0.43±0.14, P = 0.013; pathological control group vs pathological severe group, 0.74±0.18 vs 0.43±0.14, P = 0.005） according to LDS grading and pathological grading, respectively. （c） PDE; there were no significant differences among groups according to LDS grading, and no significant differences between the control group and experimental groups according to pathological grading. （2） The ratio of relative quantification of phosphorus metabolites： significant differences （P 〈 0.05） （LDS- moderate group and LDS-severe group vs LDS-control group and LDS-mild group, 1.94±0.50 and 1.96±0.72 vs 1.43±0.31 and 1.40±0.38） were only found in PDE/ATP between the moderate injured group, the severe injured group and the control group, the mild injured group. No significant difference was found in other ratios of relative quantification of phosphorus metabolites.CONCLUSION： ^31p MRS is a useful method to evaluate early acute hepatic radiation injury. The relative quantification of hepatic ATP levels, which can reflect the pathological severity of acute hepatic radiation injury, is correlated with LDS.

Hepatorenal syndrome: Update on diagnosis and treatment

Acute kidney injury(AKI) is a common complication in patients with end-stage liver disease and advanced cirrhosis regardless of the underlying cause. Hepatorenal syndrome(HRS), a functional form of kidney failure, is one of the many possible causes of AKI. HRS is potentially reversible but involves highly complex pathogenetic mechanisms and equally complex clinical and therapeutic management. Once HRS has developed, it has a very poor prognosis. This review focuses on the diagnostic approach to HRS and discusses the therapeutic protocols currently adopted in clinical practice.

Acute kidney injury from different poisonous substances

AIM To report our experience of acute kidney injury(AKI) developed after exposure to poisonous substance.METHODS Retrospective study where data was collected from case records of patients coming to this institute during January 1990 to May 2016.This institution is a tertiary care center for renal care in the metropolitan city of Karachi,Pakistan.History of ingested substance,symptoms on presentation,basic laboratory tests on arrival,mode of treatment and outcome were recorded from all patients and are presented here.Patients developing AKI after snake envenomation or scorpion stings are not included in this study.RESULTS During studied period 184 cases of AKI developing after poisoning were seen at our institution.The largest group was from paraphenyline diamine poisoning comprising 135 patients,followed by methanol in 8,organophosphorus compounds in 5,paraquat in 5,copper sulphate in 5,tartaric acid in 4,phenobarbitone in 3 and benzodiazipines,datura,rat killer,fish gall bladder,arsenic,boiler water,ammonium dichromate,acetic acid and herbs with lesser frequency.In 8 patients multiple substances were ingested in combination.Renal replacement therapy was required in 96% of patients.Complete recovery was seen in 72.28% patients,20% died during acute phase of illness.CONCLUSION It is important to report poisonous substances causing vital organ failure to increase awareness among general population as well as health care providers.

Novel biomarkers of acute kidney injury: Evaluation and evidence in urologic surgery

atients undergoing urologic surgery are at risk of acute kidney injury （AKI） and consequently long-term deterioration in renal function. AKI is further associated with signifcantly higher odds of perioperative complications, prolonged hospital stay, higher mortality and costs. Therefore, better awareness and detection of AKI, as well as identifcation of AKI determinants in the urological surgery setting is warranted to pre-empt and mitigate further deterioration of renal function in patients at special risk. New consensus criteria provide precise definitions of diagnosis and description of the severity of AKI. However, they rely on serum creatinine （SCr）, which is known to be an inaccurate marker of early changes in renal function. Therefore, several newurinary and serum biomarkers promise to address the gap associated with the use of SCr. Novel biomarkers may complement SCr measurement or most likely improve the diagnostic accuracy of AKI when used in combinations. However, novel biomarkers have to prove their clinical applicability, accuracy, and cost effectiveness prior to implementation into clinical practice. Most preferably, novel biomarkers should help to positively improve a patient’s long-term renal functional outcomes. The purpose of this review is to discuss currently available biomarkers and to review their clinical evidence within urologic surgery settings.

Clinicopathological spectrum of snake bite-induced acute kidney injury from India

AIM To study the clinico-pathological spectrum of snake bite-induced acute kidney injury(AKI).METHODS A retrospective study of patients admitted at Indira Gandhi Medical College Hospital,Shimla with snake bite-induced AKI from July 2003 to June 2016.Medical records were evaluated for patient's information on demographic,clinical characteristics,complications and outcome.Outcomes of duration of hospital stay,requirement for intensive care unit support,treatment with dialysis,survival and mortality were analyzed.The survival and non survival groups were compared to see the difference in the demographic factors,clinical characteristics,laboratory results,and complications.In patients subjected to kidney biopsy,the findings of histopathological examination of the kidney biopsies were also analyzed.RESULTS One hundred and twenty-one patients were diagnosed with snake bite-induced AKI.Mean age was 42.2 ± 15.1 years and majority(58%) were women.Clinical details were available in 88 patients.The mean duration of arrival at hospital was 3.4 ± 3.7 d with a range of 1 to30 d.Eighty percent had oliguria and 55% had history of having passed red or brown colored urine.Coagulation defect was seen in 89% patients.The hematological and biochemical laboratory abnormalities were:Anemia(80.7%),leukocytosis(75%),thrombocytopenia(47.7%),hyperkalemia(25%),severe metabolic acidosis(39.8%),hepatic dysfunction(40.9%),hemolysis(85.2%) and rhabdomyolysis(68.2%).Main complications were:Gastrointestinal bleed(12.5%),seizure/encephalopathy(10.2%),hypertension,pneumonia/acute respiratory distress syndrome(ARDS) and disseminated intravascular coagulation(9.1% each),hypotension and multi organ failure(MOF)(4.5% each).Eighty-two percent patients required renal replacement therapy.One hundred and ten(90.9%) patient survived and 11(9.1%) patients died.As compared to the survival group,the white blood cell count(P = 0.023) and bilirubin levels(P = 0.006) were significant higher and albumin levels were significantly lower(0.005) in patients who died.The proportion of patients with pneumonia/ARDS(P = 0.001),seizure/encephalopathy(P = 0.005),MOF(P = 0.05) and need for intensive care unit support(0.001) was significantly higher and duration of hospital stay was significantly shorter(P = 0.012) in patients who died.Kidney biopsy was done in total of 22 patients.Predominant lesion on kidney biopsy was acute tubular necrosis(ATN) in 20(91%) cases.In 11 cases had severe ATN and in other nine(41%) cases kidney biopsy showed features of ATN associated with mild to moderate acute interstitial nephritis(AIN).One patient only had moderate AIN and one had patchy renal cortical necrosis(RCN).CONCLUSION AKI due to snake bite is severe and a high proportion requires renal replacement therapy.On renal histology ATN and AIN are common,RCN is rare.

Use of percutaneous nephrostomy and ureteral stenting in management of ureteral obstruction

The management options for ureteral obstruction are diverse, including retrograde ureteral stent insertion or antegrade nephrostomy placement, with or without eventual antegrade stent insertion. There is currently no consensus on the ideal treatment or treatment pathway for ureteral obstruction owing, in part, to the varied etiologies of obstruction and diversity of institutional practices. Additionally, different clinicians such as internists, urologists, oncologists and radiologists are often involved in the care of patients with ureteral obstruction and may have differing opinions concerning the best management strategy. The purpose of this manuscript was to review available literature that compares percutaneous nephrostomy placement vs ureteral stenting in the management of ureteral obstruction from both benign and malignant etiologies.

Prostatic surgery associated acute kidney injury

Acute kidney injury(AKI) is associated with extended hospital stays,high risks of in-hospital and long-term mortality,and increased risk of incident and progressive chronic kidney disease.Patients with urological diseases are a high-risk group for AKI owing to the coexistence of obstructive uropathy,older age,and preexistent chronic kidney disease.Nonetheless,precise data on the incidence and outcomes of postoperative AKI in urological procedures are lacking.Benign prostatic hyperplasia and prostate cancer are common diagnoses in older men and are frequently treated with surgical procedures.Whereas severe AKI after prostate surgery in general appears to be unusual,AKI associated with transurethral resection of the prostate(TURP) syndrome and with rhabdomyolysis(RM) after radical prostatectomy have been frequently described.The purpose of this review is to discuss the current knowledge regarding the epidemiology,risk factors,outcomes,prevention,and treatment of AKI associated with prostatic surgery.The mechanisms of TURP syndrome and RM following prostatic surgeries will be emphasized.

Major comorbid disease processes associated with increased incidence of acute kidney injury

Acute kidney injury （AKI） is commonly seen amongst critically ill and hospitalized patients. Individuals with certain co-morbid diseases have an increased risk of developing AKI. Thus, recognizing the co-morbidities that predispose patients to AKI is important in AKI prevention and treatment. Some of the most common co-morbid disease processes that increase the risk of AKI are diabetes, cancer, cardiac surgery and human immunodefciency virus （HIV） acquired immune defciency syndrome （AIDS）. This review article identifies the increased risk of acquiring AKI with given co-morbid diseases. Furthermore, the pathophysiological mechanisms underlying AKI in relation to co-morbid diseases are discussed to understand how the risk of acquiring AKI is increased. This paper reviews the effects of various co-morbid diseases including： Diabetes, cancer, cardiovascular disease and HIV AIDS, which all exhibit a significant increased risk of developing AKI. Amongst these co-morbid diseases, inflammation, the use of nephrotoxic agents, and hypoperfusion to the kidneys have been shown to be major pathological processes that predisposes individuals to AKI. The pathogenesis of kidney injury is complex, however, effective treatment of the co-morbid disease processes may reduce its risk. Therefore, improved management of co-morbid diseases may prevent some of the underlying pathology that contributes to the increased risk of developing AKI.

Prevalence and outcome of acute kidney injury,as defined by the new Kidney Disease Improving Global Outcomes guideline,in very low birth weight infants

AIMTo evaluate the prevalence, risk factors and outcome of acute kidney injury （AKI） in very low birth weight （VLBW） infants. METHODSIn this retrospective study of VLBW infants, we analyzed the prevalence of AKI, as defined by changes in serum creatinine and urine output, associated risk factors and outcomes.RESULTSA total of 293 VLBW infants （mean gestational age 28.7 wk） were included, of whom 109 weighed less than 1000 g at birth. The overall prevalence of AKI was 11.6% （22% in infants with a birth weight under 1000 g and 5.4% those heavier）. A total of 19 （55%） affected infants died, with a mortality rate of 58% in infant less than 1000 g and 50% in those heavier. After adjusting for confounding variables, only necrotizing enterocolitis （NEC） remained associated with AKI, with odds ratio of 4.9 （95%CI： 1.9-18.6）. Blood pressure and glomerular filtration rate （GFR） were not different between affected infants and the others upon discharge from hospital. A normal GFR was documented in all affected infants at one year of age.CONCLUSION Using Kidney Disease Improving Global Outcomes defnition of AKI, it occurred in over 10% of VLBW infants, more commonly in infants with lower birth weight. NEC was an independent associated risk factor. Renal function, as defined by GFR, was normal in all surviving affected infants 10 to 12 mo later.

Acute kidney injury following spinal instrumentation surgery in children

AIM To determine acute kidney in jury （AKI） incidence and potential risk factors of AKI in children undergoing spinal instrumentation surgery. METHODS AKI incidence in children undergoing spinal instru-mentation surgery at British Columbia Children’s Hospital between January 2006 and December 2008 was determined by the Acute Kidney Injury Networ classification using serum creatinine and urine output criteria. During this specific time period, all patients following spinal surgery were monitored in the pediatric intensive care unit and had an indwelling Foley catheter permitting hourly urine output recording. Cases of AKI were identifed from our database. From the remaining cohort, we selected group-matched controls that did not satisfy criteria for AKI. The controls were matched for sex, age and underlying diagnosis （idiopathic vs non-idiopathic scoliosis）. RESULTS Thirty five of 208 patients met criteria for AKI with an incidence of 17% （95%CI： 12%-23%）. Of all children who developed AKI, 17 （49%） developed mild AKI （AKI Stage 1）, 17 （49%） developed moderate AKI （Stage 2） and 1 patient （3%） met criteria for severe AKI （Stage 3）. An inverse relationship was observed with AKI incidence and the amount of fluids received intra-operatively. An inverse relationship was observed with AKI incidence and the amount of fuids received intra-operatively classifed by fluid tertiles： 70% incidence in those that received the least amount of fluids vs 29% that received the most fluids （〉 7.9, P = 0.02）. Patients who developed AKI were more frequently exposed to nephrotoxins （non steroidal anti inflammatory drugs or aminoglycosides） than control patients during their peri-operative course （60% vs 22%, P 〈 0.001）. CONCLUSION We observed a high incidence of AKI following spinal instrumentation surgery in children that is potentially related to the frequent use of nephrotoxins and the amount of fuid administered peri-operatively.

Effect of TLR-4 and HO-1 on acute lung injury induced by hemorrhagic shock in mice

Objective： To examine whether TLR-4 has an ettect on hemorrhage induced changes in lung, and to investigate the change of heme oxygenase-1 （HO-1） on acute lung injury （ALl） induced by hemorrhagic shock in mice. Methods： Forty-eight male mice, including C3H/HeN mice and C3H/HeJ mice, were randomly divided into sham group （n=12）, hemorrhagic shock group with twelve mice in each phase. Blood pressure （BP） was monitored continuously by attaching carotid artery catheter to a strain gauge pressure transducer/ polygraph. Arterial blood samples were taken for blood gas analysis. A mouse model of non-lethal hemorrhagic shock and resuscitation was used to observe pulmonary myeloperoxidase （MPO） activity and wet/dry weight ratio （W/D）. The expression of HO- 1 was observed by means of RT-PCR and immunohistochemistry. IL-6 and IL-10 in lung tissue homogenate were assayed by enzyme-linked immunosorbent assay （ELISA）. The pulmo- nary pathologic changes were observed under electron microscope and light microscope. Results： Compared with sham group, the expression of HO- 1 in lung tissue was significantly higher in Hem 24 h and Hem 48 h of C3H/HeN mice （P〈0.01）. The expression of HO-1 mRNA and the levels of IL-6, IL-10 and MPO in lung tissue were markedly increased in Hem 24 h （P〈0.01 or P〈0.05）; Compared with C3H/HeN mice, the expression of HO- 1 rnRNA and the levels of IL-6 and IL-10 in C3H/HeJ mice significantly decreased in Hem 24 h and Hem 48 h （P〈0.01 or P〈O.05）, and the W/D, MPO in C3H/HeJ mice were obvi- ously lower in Hem 24 h （P〈0.05）. The injuries of lung tissues after hemorrhagic shock have been demonstrated by histological examination with electron microscope and light microscope. Conclusions： TLR-4 and HO-1 might modulate the bal- ance of pro- and anti-inflammatory processes in inflamma- tory reaction of hemorrhagic shock-induced ALl, and the activation of Toll-like receptor might induce the transcrip- tion activity of HO- 1, which may play a key role in acute lung injury.

Effects of mild hypothermia on patients with lower intracranial pressure following severe brain injury

Objective: To study the effects of mild hypothermia therapy on severe brain-injured patients whose intracranial pressure (ICP) could be maintained below 25 mm Hg.Methods: Forty severe brain-injured patients with ICP below 25 mm Hg were divided randomly into one treatment group (n=20, mild hypothermia therapy) and one control group (n=20, normothermia therapy) to observe the changes of the concentration of excitatory amino acids (glutamate and glycine) and cytokines (interleukin-1β and interleukin-6). Results: There were no significant differences in the daily changes of the concentration of excitatory amino acid and cytokines between two groups. The outcome of two groups had no significant differences. Conclusions: Mild hypothermia has no additional beneficial effects on severe brain-injured patients compared with normothermia therapy if ICP can be maintained below 25 mm Hg by using conventional therapy.

Biological modalities for treatment of acute spinal cord injury： a pilot study and review of the literature

Objective： Paraplegia due to traumatic spinal cord injuries is one of the devastating effects of dorsolumbar vertebral fractures. Treatment modalities for such fractures, such as stabilization, have no effect on the neurological recovery. Thus, various pharmacological and biological treatment modalities have been used. The more recent trend of using autologous stem cells from the iliac crest has been used in some clinical trials with varying success. Thus, more clinical studies are required to study the effect of this novel approach Methods： This is a prospective hospital-based cohort study （level IV）. The study was conducted in the Dept. of Orthopaedics, University College of Medical Sciences and GTB Hospital, Delhi from November 2010 to March 2012. Ten patients who had sustained traumatic dorsolumbar vertebral fractures with complete paraplegia were recruited for this study. Under suitable anaesthesia, at the beginning of surgery, 100 ml of bone marrow was aspirated. This was centrifuged and buffy coat isolated and then transferred into a sterile tube and sent to the operating room on ice packs. After surgical decompression and stabilization, the buffy coat isolate was injected into the dural sleeve at the site of the injury using a 21G needle. All the patients were evaluated for neurological improvement using the American Spinal Injury Association （ASIA） score and Frankel grade at 6 weeks and 3 months postoperatively. Results： The evaluation at 6 weeks showed some improvement in terms of the ASIA scores in 2 patients but no improvements in their Frankel Grade. The other 8 patients showed no improvements in their ASIA scores or their Frankel Grades. The current pilot study has shown that there has been no improvement in most of the recipients of the transplant （n=8）. Some patients （n=2） who did show some improvement in their sensory scores proved to be of no significant functional value as depicted by no change in their Frankel Grades. Conclusion： The outcome of current study shows that although this modality of treatment is safe for the patients, it provides no additional benefits on improvement of quality of life among these patients.