Acute renal failure. Multivariate analysis of causes and risk factors

An interpretable machine learning model for the prevention of contrast-induced nephropathy in patients undergoing lower extremity endovascular interventions for peripheral arterial disease

BACKGROUND

Contrast-induced nephropathy (CIN) is a postprocedural complication associated with increased morbidity and mortality. An important risk factor for development of CIN is renal impairment. Identification of patients at risk for acute renal failure will allow physicians to make appropriate decisions to minimize the incidence of CIN. We developed a machine learning model to stratify risk of acute renal failure that may assist in mitigating risk for CIN in patients with peripheral artery disease (PAD) undergoing endovascular interventions.

METHODS

We utilized the American College of Surgeons National Surgical Quality Improvement Program database to extract clinical and laboratory information associated with 14,444 patients who underwent lower extremity endovascular procedures between 2011 and 2018. Using 11,604 cases from 2011 to 2017 for training and 2840 cases from 2018 for testing, we developed a random forest model to predict risk of 30-day acute renal failure following infra-inguinal endovascular procedures.

RESULTS

Eight variables were identified as contributing optimally to model predictions, the most important being diabetes, preoperative BUN, and claudication. Using these variables, the model achieved an area under the receiver-operating characteristic (AU-ROC) curve of 0.81, accuracy of 0.83, sensitivity of 0.67, and specificity of 0.74. The model performed equally well on white and nonwhite patients (Delong p-value = 0.955) and patients age < 65 and patients age ≥ 65 (Delong p-value = 0.659).

CONCLUSIONS

We develop a model that fairly and accurately stratifies 30-day acute renal failure risk in patients undergoing lower extremity endovascular procedures for PAD. This model may assist in identifying patients who may benefit from strategies to prevent CIN.

A real-world prospective study on dialysis-requiring acute kidney injury

Background

Current information about acute kidney injury (AKI) epidemiology in developing nations derives mainly from isolated centers, with few quality multicentric epidemiological studies. Our objective was to describe a large cohort of patients with dialysis-requiring AKI derived from ordinary clinical practice within a large metropolitan area of an emerging country, assessing the impact of age and several clinical predictors on patient survival across the spectrum of human life.

Methods

We analyzed registries drawn from 170 hospitals and medical facilities in Rio de Janeiro, Brazil, in an eleven-year period (2002–2012). The study cohort was comprised of 17,158 pediatric and adult patients. Data were analyzed through hierarchical logistic regression models and mixed-effects Cox regression for survival comparison across age strata.

Results

Severe AKI was mainly hospital-acquired (72.6%), occurred predominantly in the intensive care unit (ICU) (84.9%), and was associated with multiple organ failure (median SOFA score, 11; IQR, 6–13). The median age was 75 years (IQR, 59–83; range, 0–106 years). Community-acquired pneumonia was the most frequent admission diagnosis (23.8%), and sepsis was the overwhelming precipitating cause (72.1%). Mortality was 71.6% and was higher at the age extremes. Poor outcomes were driven by age, mechanical ventilation, vasopressor support, liver dysfunction, type 1 cardiorenal syndrome, the number of failing organs, sepsis at admission, later sepsis, the Charlson score, and ICU admission. Community-acquired AKI, male gender, and pre-existing chronic kidney disease were associated with better outcomes.

Conclusions

Our study adds robust information about the real-world epidemiology of dialysis-requiring AKI with considerable clinical detail. AKI is a heterogeneous syndrome with variable clinical presentations and outcomes, including differences in the age of presentation, comorbidities, frailty state, precipitation causes, and associated diseases. In the cohort studied, AKI characteristics bore more similarities to upper-income countries as opposed to the pattern traditionally associated with resource-limited economies.

Evaluation of Myoglobin Clearance during Continuous Hemofiltration in a Swine Model of Acute Renal Failure

Rhabdomyolysis is characterized by extensive damage of striated muscle, while the major complication of this disease is the development of acute myoglobinuric renal failure. Although first described more than five decades ago very little has changed with regard to the management of this entity as conventional hemodialysis has not been shown to effect myoglobin elimination. However, continuous arteriovenous hemofiltration (CAVH) offers an alternative to conventional hemodialysis as this procedure is more effective particularly for removing larger molecular weight substances such as myoglobin. We studied the effect of CAVH on myoglobin clearance in an animal model of acute myoglobinuric renal failure. Swine (n=6) were given 4 grams of equine myoglobin intravenously and underwent the CAVH procedure for six hours each. Once the filtering process was initiated there was a rapid and sustained production of ultrafiltrate. The clearance of myoglobin via the hemofilter was 2.05 ± 1.48 L/day. The amount of myoglobin excreted in the ultrafiltrate over the six hour filtering period was 410 ± 234 mg which accounts for 10.27 ± 5.85 percent of the administered dose. Based on these findings, it appears that the hemofiltration system is a viable option for the removal of myoglobin from the systemic circulation.

Myoglobin Clearance during Continuous Veno-Venous Hemofiltration with or without Dialysis

The management of acute myoglobinuric renal failure, the major complication of rhab-domyolysis, continues to be a treatment dilemma for the clinician as limited therapeutic options are available. Previously, we have demonstrated that continuous arteriovenous hemofiltration (CAVH) is an effective technique for removing myoglobin in an animal model. In the present study, swine were administered four grams of equine myoglobin intravenously and underwent the continuous veno-venous hemofiltration (CVVH) procedure for six hours each. Animals were studied in each of the following groups: CVVH at a pump rate 100 ml/minute, CVVH at a pump rate 200 ml/minute and CVVH at a pump rate 100 ml/minute plus dialysis at a dialysate flow rate of one Liter/h. Once the filtering process was initiated there was a rapid and sustained production of ultrafiltrate in all groups. The amount of myoglobin excreted in the ultrafiltrate over the six-hour filtering period was 688, 948 and 570 mg which corresponded to 17, 24 and 14 percent of the administered dose, respectively, for the three treatments. In comparison to previous CAVH experiments, CVVH removed more circulating myoglobin and the addition of the dialysis component did not appear to improve removal. Based on these findings, it appears that the CVVH hemofiltration system is a viable option for the removal of systemic myoglobin.

Post-traumatic acute kidney injury: a cross-sectional study of trauma patients

BACKGROUND

The causes of post-traumatic acute kidney injury (AKI) are multifactorial, and shock associated with major trauma has been proposed to result in inadequate renal perfusion and subsequent AKI in trauma patients. This study aimed to investigate the true incidence and clinical presentation of post-traumatic AKI in hospitalized adult patients and its association with shock at a Level I trauma center.

METHODS

Detailed data of 78 trauma patients with AKI and 14,504 patients without AKI between January 1, 2009 and December 31, 2014 were retrieved from the Trauma Registry System. Patients with direct renal trauma were excluded from this study. Two-sided Fisher's exact or Pearson's chi-square tests were used to compare categorical data, unpaired Student's t-test was used to analyze normally distributed continuous data, and Mann-Whitney's U test was used to compare non-normally distributed data. Propensity score matching with a 1:1 ratio with logistic regression was used to evaluate the effect of shock on AKI.

RESULTS

Patients with AKI presented with significantly older age, higher incidence rates of pre-existing comorbidities, higher odds of associated injures (subdural hematoma, intracerebral hematoma, intra-abdominal injury, and hepatic injury), and higher injury severity than patients without AKI. In addition, patients with AKI had a longer hospital stay (18.3 days vs. 9.8 days, respectively; P < 0.001) and intensive care unit (ICU) stay (18.8 days vs. 8.6 days, respectively; P < 0. 001), higher proportion of admission into the ICU (57.7% vs. 19.0%, respectively; P < 0.001), and a higher odds ratio (OR) of short-term mortality (OR 39.0; 95% confidence interval, 24.59-61.82; P < 0.001). However, logistic regression analysis of well-matched pairs after propensity score matching did not show a significant influence of shock on the occurrence of AKI.

DISCUSSION

We believe that early and aggressive resuscitation, to avoid prolonged untreated shock, may help to prevent the occurrence of post-traumatic AKI. However, more evidence is required to support this observation.

CONCLUSION

Compared to patients without AKI, patients with AKI presented with different injury characteristics and worse outcome. However, an association between shock and post-traumatic AKI could not be identified.

Acute Renal Failure in Critically Ill Patients

Acute renal failure is an important cause of morbidity in critically ill patients. Acute renal failure results from pre renal and postrenal causes and, most importantly, acute tubular necrosis (ATN). Although it is known that renal toxins and renal ischemia are the most common causes of ATN in hospitalized patients, the exact pathogenesis of this entity is still not fully understood. Patients in the intensive care unit are at high risk for ATN because of hemodynamic instability, the administration of neph rotoxic antibiotics or chemotherapeutic agents, and ex posure to radiographic contrast agents. The acquired immunodeficiency syndrome is also associated with an increased risk of renal failure development, either from complications of the disease itself or from its treatment. Many consequences of acute renal failure such as vol ume overload, acidosis, hyperkalemia, and serositis can be managed adequately with peritoneal dialysis, hemo dialysis, or a newer technique, continuous arteriove nous hemofiltration. Despite improvements in treat ment, however, the mortality of ATN remains high. In this review, we recommend measures to prevent ATN in certain clinical situations that commonly occur among critically ill patients. We also review therapeutic options for treating patients in whom acute renal failure devel ops and discuss newer developments that may begin to reduce the excessive morbidity associated with ATN.

How to manage patients on rivaroxaban in the emergency department: a statement of the Italian society of emergency medicine advisory board

Rivaroxaban, a new oral anticoagulant, has been approved in many countries and its everyday use in clinical practice is increasing. Thus, the chances for an emergency physician to encounter rivaroxaban-treated patients in emergency situations have increased. Here, the authors address the main issues in terms of the prescription of rivaroxaban and the management of these patients in cases of minor or major bleeding, urgent surgery, atrial fibrillation requiring cardioversion, acute ischemic stroke, ST-elevation myocardial infarction, and new onset of atrial fibrillation in recent ST-elevation myocardial infarction. The recommendations reached are based on a literature review and a panel discussion of the advisory board of SIMEU, the Italian Society of Emergency Medicine.

Evaluation of Serum Creatine Kinase and Urinary Myoglobin as Markers in Detecting Development of Acute Renal Failure in Severely Injured Trauma Patients

Background. Presence of myoglobinuria, particularly in the early phases of renal failure, and elevation of creatinine kinase are seen to correlate with the development of acute renal failure. Aim. To evaluate the efficiency of serum creatine kinase (CK) and urine myoglobin in assessing development of renal failure. Materials and Method. We prospectively studied trauma patients over a period of 3 months. Samples of 107 patients were routinely analyzed on the 1st, 3rd, and 5th days post trauma, for myoglobinuria and serum CK concentration. Results. 107 patients with median age 28 (4–83) yrs were studied, of which 83.2% were males. 56% had head injury, and 17.1% had high injury severity (ISS > 24). Incidence of renal failure was 9.3%. Myoglobinuria was present in 57 patients on admission, 33 on 3rd day and 22 on the 5th day. The association of myoglobinuria with renal failure was statistically insignificant. The cutoff values of serum CK on the 1st, 3rd, and 5th days were ≥1320 IU/L, ≥1146 IU/L, and ≥1754 IU/L, respectively. Mortality rate was 24 (22.4%), of which 6 had renal failure. Conclusion. Myoglobin is clinically insignificant in the detection of renal failure; serum CK is a sensitive predicting marker for the progression of renal failure following traumatic injury.

Clinical review: Volume of fluid resuscitation and the incidence of acute kidney injury - a systematic review

Intravenous fluids are widely administered to maintain renal perfusion and prevent acute kidney injury (AKI). However, fluid overload is of concern during AKI. Using the Pubmed database (up to October 2011) we identified all randomised controlled studies of goal-directed therapy (GDT)-based fluid resuscitation (FR) reporting renal outcomes and documenting fluid given during perioperative care. In 24 perioperative studies, GDT was associated with decreased risk of postoperative AKI (odds ratio (OR) = 0.59, 95% confidence interval (CI) = 0.39 to 0.89) but additional fluid given was limited (median: 555 ml). Moreover, the decrease in AKI was greatest (OR = 0.47, 95% CI = 0.29 to 0.76) in the 10 studies where FR was the same between GDT and control groups. Inotropic drug use in GDT patients was associated with decreased AKI (OR = 0.52, 95% CI = 0.34 to 0.80, P = 0.003), whereas studies not involving inotropic drugs found no effect (OR = 0.75, 95% CI = 0.37 to 1.53, P = 0.43). The greatest protection from AKI occurred in patients with no difference in total fluid delivery and use of inotropes (OR = 0.46, 95% CI = 0.27 to 0.76, P = 0.0036). GDT-based FR may decrease AKI in surgical patients; however, this effect requires little overall FR and appears most effective when supported by inotropic drugs.

Risk of acute renal failure in patients with Type 2 diabetes mellitus

AIMS

Progressive decline in renal function has been well described in patients with Type 2 diabetes mellitus, but few studies have assessed the risk of acute renal failure in a large population of patients with Type 2 diabetes. This study quantified the risk of acute renal failure associated with Type 2 diabetes in the General Practice Research Database from the UK.

METHODS

Patients with Type 2 diabetes (n = 119,966) and patients without diabetes (n = 1,794,516) were identified in the General Practice Research Database. Patients with end-stage renal disease were excluded. Crude incidence and multivariate-adjusted hazard ratios of acute renal failure were estimated for patients with diabetes relative to those without diabetes. Cox regression models were adjusted for a variety of comorbidities. Increase of acute renal failure risk resulting from additive effects of specific co-morbidities with Type 2 diabetes was also assessed.

RESULTS

Between 2003 and 2007, acute renal failure incidence was 198 per 100,000 person-years in patients with Type 2 diabetes compared with 27 per 100,000 patients-years among patients without diabetes (crude hazard ratio 8.0, 95% CI 7.4-8.7). Risk of acute renal failure for patients with Type 2 diabetes remained significant, but was attenuated in multivariate analyses adjusting for various comorbidities (adjusted hazard ratio 2.5, 95% CI 2.2-2.7). Age and specific comorbidities (chronic kidney disease, hypertension and congestive heart failure) were also associated with increased risk of acute renal failure in Type 2 diabetes.

CONCLUSIONS

Patients with Type 2 diabetes have increased risk for acute renal failure compared with patients without diabetes, even after adjustment for known risk factors, particularly in the elderly and those with other comorbidities such as chronic kidney disease, congestive heart failure and hypertension.

Renal endocrine manifestations during polytrauma: A cause of concern for the anesthesiologist

Nowadays, an increasing number of patients get admitted with polytrauma, mainly due to road traffic accidents. These polytrauma victims may exhibit associated renal injuries, in addition to bone injuries and injuries to other visceral organs. Nevertheless, even in cases of polytrauma, renal tissue is hyperfunctional as part of the normal protective responses of the body to external insults. Both polytrauma and renal injuries exhibit widespread renal, endocrine, and metabolic responses. The situation is very challenging for the attending anesthesiologist, as he is expected to contribute immensely, not only in the resuscitation of such patients, but if required, to allow the operative procedures in case of life-threatening injuries. During administration of anesthesia, care has to be taken, not only to maintain hemodynamic stability, but equal attention has to be paid to various renal protection strategies. At the same time, various renoendocrine manifestations have to be taken into account, so that a judicious use of anesthesia drugs can be made, to minimize the renal insults.

Acute kidney injury after cardiac surgery in infants and children: evaluation of the role of angiotensin-converting enzyme inhibitors

Children with congenital heart disease who undergo cardiac surgery are vulnerable to acute kidney injury (AKI). This study sought to evaluate the role of angiotensin-converting enzyme (ACE) inhibitors and other nephrotoxic medications in the risk for the development of AKI in neonates and children undergoing cardiac surgery. A retrospective review of all patients younger than 2 years admitted to the cardiac intensive care unit after cardiac surgery from March 2007 to September 2008 was conducted. Patients were included in the review if they received furosemide alone or in combination with an ACE inhibitor. Creatinine clearance was calculated, and the patient's maximal degree of AKI was classified by pRIFLE. A P value less than 0.05 was considered significant. Of the 319 patients who met the inclusion criteria, 149 (47%) received furosemide therapy alone and 170 (53%) received a combination of furosemide and an ACE inhibitor. Patients in the furosemide-only group (age, 5 months) were older than the patients who received both furosemide and an ACE inhibitor (age, 3.8 months; P = 0.024). Despite statistically higher Aristotle scores in the ACE-inhibitor group, the intraoperative variables did not differ between the two groups. Postoperatively, the ACE-inhibitor group had a decreased creatinine clearance (55.3 ml/min/1.73 m(2)) compared with the furosemide group (64.4 ml/min/1.73 m(2); P = 0.015) and an increased incidence of a pRIFLE maximal score of "F" (odds ratio [OR], 1.75; P = 0.033). However, after adjustment for additional risk factors, no difference in the occurrence of AKI resulted (OR, 0.939; P = 0.85) when patients received an ACE inhibitor. More than half of the study population received ACE inhibitors, but this treatment was not associated with an increase in AKI.

Clinical cause of presumed acute tubular necrosis requiring renal replacement therapy and outcome of critically ill patients: post hoc analysis of a prospective 7-year cohort study

BACKGROUND

Acute kidney injury (AKI) secondary to acute tubular necrosis (ATN) is common in critically ill patients, and causes significant morbidity and mortality. The underlying etiology of ATN can be divided into pure ischemic, pure nephrotoxic, and mixed causes. This post-hoc analysis of a prospective cohort study aimed to investigate whether the cause (pure vs. mixed) of ATN affects the short- and long-term outcome of critically-ill patients.

METHODS

A total of 425 critically-ill patients with AKI secondary to clinically diagnosed ATN were divided into three groups according to the cause of ATN. Of these patients, 215 had mixed ATN, 203 had pure ischemic ATN, and seven had pure nephrotoxic ATN. All patients had one episode of AKI only. No patient had pre-existing chronic kidney disease. Patients were followed throughout their hospital stay (mortality rate, recovery of renal function at discharge) and up to 7 years thereafter.

RESULTS

The three patient groups differed in their demographic and clinical characteristics. The in-hospital mortality rates were 55% in the presumably mixed-cause ATN group, 39% in the pure ischemic group, and 29% in the pure nephrotoxic group. Complete renal recovery at discharge was documented in five out of five surviving patients with nephrotoxic ATN (100%) and in 92 out of 124 surviving patients with pure ischemic ATN (74%), but only in 29 out of 97 patients with mixed ATN (30%). None of the surviving patients was lost during the 7-year follow-up. At the end of the observation period, 60% of the survivors of pure ATN, compared with 22% of the survivors of mixed ATN, were alive. After 7 years, 6% of the living patients with pure ATN had mild-to-moderate chronic kidney disease, whereas 38% of the mixed group patients had advanced CKD or end-stage renal disease.

CONCLUSIONS

The cause of presumed ATN has a profound impact on short- as well as long-term outcomes of critically-ill patients with AKI requiring renal replacement therapy. The challenge for intensivists is to avoid further injury to the kidneys of these patients.

Acute kidney injury after trauma: Prevalence, clinical characteristics and RIFLE classification

BACKGROUND

Acute kidney injury (AKI) is an uncommon but serious complication after trauma. The objective of this study was to evaluate the prevalence, clinical characteristics and outcome of AKI after trauma.

PATIENTS AND METHODS

This was a retrospective study performed from January 2006 to January 2008 in an emergency specialized hospital in Fortaleza city, northeast of Brazil. All patients with AKI admitted in the study period were included. Prevalence of AKI, clinical characteristics and outcome were investigated.

RESULTS

Of the 129 patients admitted to the intensive care unit (ICU), 52 had AKI. The mean age was 30.1 ± 19.2 years, and 79.8% were males. The main causes of AKI were sepsis in 27 cases (52%) and hypotension in 18 (34%). Oliguria was observed in 33 cases (63%). Dialysis was required for 19 patients (36.5%). Independent risk factors associated with AKI were abdominal trauma [odds ratio (OR) = 3.66, P = 0.027] and use of furosemide (OR = 4.10, P = 0.026). Patients were classified according to RIFLE criteria as Risk in 12 cases (23%), Injury in 13 (25%), Failure in 24 (46%), Loss in 1 (2%) and End-stage in 2 (4%). Overall in-hospital mortality was 95.3%. The main cause of death was sepsis (24%). Mortality was 100% among patients with AKI.

CONCLUSIONS

AKI is a fatal complication after trauma, which presented with a high mortality in the studied population. A better comprehension of factors associated with death in trauma-associated AKI is important, and more effective measures of prevention and treatment of AKI in this population are urgently needed.

Utility of urine myoglobin for the prediction of acute renal failure in patients with suspected rhabdomyolysis: a systematic review

BACKGROUND

Urine myoglobin continues to be used as a marker of rhabdomyolysis, particularly to assess risk of developing acute renal failure and evaluate treatment success. We sought to determine the predictive validity of urine myoglobin (uMb) for acute renal failure (ARF) in patients with suspected rhabdomyolysis.

METHODS

We performed a broad systemic review of the literature from January 1980 to December 2006 using the search terms myoglobin$ AND (renal OR ARF OR kidney). Only primary studies published in English where uMb measurement was related to ARF were included.

RESULTS

Of 1602 studies screened, 52 met all selection criteria. The studies covered a wide spectrum of etiologies for rhabdomyolysis, dissimilar diagnostic criteria for ARF and rhabdomyolysis, and various methods of uMb measurement and were mostly case series (n = 32). There was poor reporting on the uMb method, and 17 studies failed to provide any information about the method. The reporting of clinical criteria for ARF with respect to timing, description, performance, and interpretation also lacked adequate detail for replication. Eight studies (total 295 patients) had data for 2-by-2 tables. Sensitivity of the uMb test was 100% in 5 of the 8 studies, specificity varied widely (15% to 88%), and CIs around these measures were high. Pooling of data was not possible because of study heterogeneity.

CONCLUSIONS

There is inadequate evidence evaluating the use of uMb as a predictor of ARF in patients with suspected rhabdomyolysis.

Causes and Prognosis of Nontraumatic Acute Renal Failure Requiring Dialysis in Adult Patients with and without Diabetes

Despite advanced techniques of renal replacement therapy the overall mortality of patients with ARF is still high. The majority of patients with ARF requiring dialysis are those with nontraumatic ARF. In a retrospective study we compared the causes of nontraumatic ARF, the risk factors for the development of renal failure and the mortality rates in patients with and without diabetes mellitus who received dialysis therapy in the years 1991-2000. A total of 232 patients were included in the study, 34 (14.6%) of them with and 198 patients (85.4%) without diabetes. The predominant causes of nontraumatic ARF like congestive heart failure (26.4 vs. 13.6, p < 0.05) and hypotension/hypovolemia (20.6 vs. 7.6%, p < 0.05) occurred more frequently in diabetic patients. The prevalence of sepsis (8.8 vs. 10.1%, NS), malignancy/ hypercalcemia (5.8 vs. 11.6%, NS) and other causes of nontraumatic ARF were similar in both groups. The prevalence of hepato-renal syndrome (5.8 vs. 13.6%, p < 0.05) and acute kidney graft failure (2.9 vs. 15.1%, p < 0.05) was higher in the nondiabetic individuals. Patients with diabetes showed more often chronic predictors for the onset of ARF like pre-existing hypertension (93.6 vs. 51.0%, p < 0.05), congestive heart failure (44.1 vs. 14.6%, p < 0.005), pre-existing renal insufficiency (76.4 vs. 46.9%, p < 0.05) and ACE-inhibitor therapy (32.3 vs. 9.6%, p < 0.005). Additionally, the prevalence of multiple organ failure (MOF) as prognostic factor was significantly higher in the diabetic patients (47.0 vs. 21.7%, p < 0.05). The mean number of dialyses therapy was 4.7 vs. 4.5 per patient. The overall mortality was 41.1 vs. 44.% (NS). In conclusion, the prevalence of the most common causes of nontraumatic ARF was different between the patients with and without diabetes. The diabetic individuals had more frequently predictors for the onset of ARF. The overall mortality was approximately the same in both groups.

Nephrotoxicity as a cause of acute kidney injury in children

Many different drugs and agents may cause nephrotoxic acute kidney injury (AKI) in children. Predisposing factors such as age, pharmacogenetics, underlying disease, the dosage of the toxin, and concomitant medication determine and influence the severity of nephrotoxic insult. In childhood AKI, incidence, prevalence, and etiology are not well defined. Pediatric retrospective studies have reported incidences of AKI in pediatric intensive care units (PICU) of between 8% and 30%. It is widely recognized that neonates have higher rates of AKI, especially following cardiac surgery, severe asphyxia, or premature birth. The only two prospective studies in children found incidence rates of 4.5% and 2.5% of AKI in children admitted to PICU, respectively. Nephrotoxic drugs account for about 16% of all AKIs most commonly associated with AKI in older children and adolescents. Nonsteroidal anti-inflammatory drugs (NSAIDs), antibiotics, amphotericin B, antiviral agents, angiotensin-converting enzyme (ACE) inhibitors, calcineurin inhibitors, radiocontrast media, and cytostatics are the most important drugs to indicate AKI as significant risk factor in children. Direct pathophysiological mechanisms of nephrotoxicity include constriction of intrarenal vessels, acute tubular necrosis, acute interstitial nephritis, and-more infrequently-tubular obstruction. Furthermore, AKI may also be caused indirectly by rhabdomyolysis. Frequent therapeutic measures consist of avoiding dehydration and concomitant nephrotoxic medication, especially in children with preexisting impaired renal function.

Early detection of acute kidney injury: emerging new biomarkers

Acute kidney injury (AKI) has recently become the preferred term to describe the syndrome of acute renal failure (ARF) with 'failure' or 'ARF' restricted to patients who have AKI and need renal replacement therapy.(1) This allows capture of the broader clinical spectrum of modest reductions in creatinine, which are themselves known to be associated with major increases in both short- and long-term mortality risk.(2-5) It is hoped that this change in nomenclature will facilitate an expansion of our understanding of the underlying pathophysiology and also facilitate definitions of AKI, which allow comparisons among clinical trials of patients with similar duration and severity of illness. This review will cover the need for early detection of AKI and the role of urinary and plasma biomarkers, including enzymuria. The primary message is that use of existing criteria to diagnose AKI, namely elevation of the serum creatinine with or without oliguria, results in identification that is too late to allow successful intervention. New biomarkers are essential to change the dire prognosis of this common condition.

Drug-induced arthritic and connective tissue disorders

OBJECTIVES

All pharmacologic agents have the potential for both benefit and toxicity. Among the more interesting and important adverse consequences of drug therapy are a range of joint and connective tissue complaints that may mimic or reproduce primary rheumatologic diseases. In this article, we review the literature on commonly used drugs reported to induce arthritis and/or connective tissue-based diseases. We assess the strength of the reported associations, discuss diagnostic features and treatment implications, and consider possible mechanisms for drug-induced genesis of rheumatic conditions.

METHODS

We reviewed the Medline database from 1987 to 2006 to identify drug-induced arthritic and connective-tissue disease syndromes, utilizing 48 search terms. A qualitative review was performed after the articles were abstracted and the relevant information was organized.

RESULTS

Three hundred fifty-seven articles of possible relevance were identified. Two hundred eleven publications were included in the final analysis (case series and reports, clinical trials, and reviews). Many drugs were identified as mimicking existing rheumatic conditions, including both well-established small molecules (eg, sulfasalazine) and recently introduced biologic agents (eg, antitumor necrosis factor agents). The most commonly reported drug-induced rheumatic conditions were lupus-like syndromes. Arthritis and vasculitis were also often reported.

CONCLUSIONS

Drug-induced rheumatic syndromes are manifold and offer the clinician an opportunity to define an illness that may remit with discontinuation of the offending agent. Early diagnosis and withdrawal of the drug may prevent unnecessary morbidity and disability.

Acute kidney injury prediction following elective cardiac surgery: AKICS Score

Acute kidney injury (AKI) following cardiac surgery (AKICS) is associated with increased postoperative (post-op) morbidity and mortality. A prognostic score system for AKI would help anticipate patient (pt) treatment. To develop a predictive score (AKICS) for AKI following cardiac surgery, we used a broad definition of AKI, which included perioperative variables. Six hundred three pts undergoing cardiac surgery were prospectively evaluated for AKI defined as serum creatinine above 2.0 mg/dl or an increase of 50% above baseline value. Univariate and multivariate analyses were used to evaluate pre-, intra-, and post-op parameters associated with AKI. The AKICS scoring system was prospectively validated in a new data set of 215 pts with an incidence of AKI of 14%. Variables included in the AKICS score were age greater than 65, pre-op creatinine above 1.2 mg/dl, pre-op capillary glucose above 140 mg/dl, heart failure, combined surgeries, cardiopulmonary bypass time above 2 h, low cardiac output, and low central venous pressure. The AKICS score presented good calibration and discrimination in both the study group and validation data set. The AKICS system that we developed, which incorporates five risk categories, accurately predicts AKI following cardiac surgery.

Risk factors for acute renal failure: inherent and modifiable risks

PURPOSE OF REVIEW

Our purpose is to discuss established risk factors in the development of acute renal failure and briefly overview clinical markers and preventive measures.

RECENT FINDINGS

Findings from the literature support the role of older age, diabetes, underlying renal insufficiency, and heart failure as predisposing factors for acute renal failure. Diabetics with baseline renal insufficiency represent the highest risk subgroup. An association between sepsis, hypovolemia, and acute renal failure is clear. Liver failure, rhabdomyolysis, and open-heart surgery (especially valve replacement) are clinical conditions potentially leading to acute renal failure. Increasing evidence shows that intraabdominal hypertension may contribute to the development of acute renal failure. Radiocontrast and antimicrobial agents are the most common causes of nephrotoxic acute renal failure. In terms of prevention, avoiding nephrotoxins when possible is certainly desirable; fluid therapy is an effective prevention measure in certain clinical circumstances. Supporting cardiac output, mean arterial pressure, and renal perfusion pressure are indicated to reduce the risk for acute renal failure. Nonionic, isoosmolar intravenous contrast should be used in high-risk patients. Although urine output and serum creatinine lack sensitivity and specificity in acute renal failure, they remain the most used parameters in clinical practice.

SUMMARY

There are identified risk factors of acute renal failure. Because acute renal failure is associated with a worsening outcome, particularly if occurring in critical illness and if severe enough to require renal replacement therapy, preventive measures should be part of appropriate management.

Organ dysfunction during sepsis

BACKGROUND

Multiple organ dysfunction syndrome is the commonest reason for sepsis-associated mortality.

DISCUSSION

In the 40 years since it was first described understanding of its pathophysiology has improved, and novel methodologies for monitoring and severity of illness scoring have emerged. These, together with the development of systematic strategies for managing organ dysfunction in sepsis, and potentially effective new therapeutic interventions, should assist in reducing sepsis-associated mortality.

CONCLUSION

These historical developments are discussed, and the reader is directed to these references for further guidance.

Renal medullary tissue oxygenation is dependent on both cortical and medullary blood flow

The aim of the current study was to determine whether renal medullary oxygenation is independent of the level of cortical blood flow by testing responses to stimuli that selectively reduce blood flow in either the cortex or medulla. In anesthetized rabbits, renal arterial infusion of [Phe(2),Ile(3),Orn(8)]-vasopressin selectively reduced medullary perfusion and Po(2) (-54 +/- 24 and -50 +/- 10%, respectively) but did not significantly affect cortical perfusion or tissue oxygenation. In contrast, stimulation of the renal nerves resulted in renal cortical ischemia with reductions in total renal blood flow (-76 +/- 3% at 4 Hz), cortical perfusion (-57 +/- 17%), and cortical Po(2) (-44 +/- 12%). Medullary tissue Po(2) was reduced by -70 +/- 5% at 4 Hz, despite medullary perfusion being unaffected and distal tubular sodium reabsorption being reduced (by -83.3 +/- 1.2% from baseline). In anesthetized rats, in which renal perfusion pressure was maintained with an aortic constrictor, intravenous infusion of ANG II (0.5-5 microg. kg(-1).min(-1)) dose dependently reduced cortical perfusion (up to -65 +/- 3%; P < 0.001) and cortical Po(2) (up to -57 +/- 4%; P < 0.05). However, medullary perfusion was only significantly reduced at the highest dose (5 microg. kg(-1).min(-1); by 29 +/- 6%). Medullary perfusion was not reduced by 1 microg. kg(-1).min(-1) ANG II, but medullary Po(2) was significantly reduced (-12 +/- 4%). Thus, although cortical and medullary blood flow may be independently regulated, medullary oxygenation may be compromised during moderate to severe cortical ischemia even when medullary blood flow is maintained.

Nephrotoxicity associated with exposure to plant toxins, with particular reference to Africa

Acute renal failure is a frequent cause of morbidity and mortality in the hospitalized population worldwide. In Africa, apart from hemodynamic causes and infections, herbal remedies contribute to both morbidity and mortality, although these causes often go unrecognized. This paper reviews reports of herbal remedies that have been shown to result in nephrotoxicity. The indications for use of the remedies, signs and symptoms in poisoned patients, and the methods used to detect toxic compounds in plant specimens or in biological fluids are covered.

Contrast Dose-to-Creatinine Clearance Ratio as a Potential Indicator of Risk for Radiocontrast-Induced Nephropathy

OBJECTIVES

Identification of risk factors is important for preventing radiocontrast-induced nephropathy (RCIN). Contrast dose and renal function have been shown in most but not all studies to be risk factors for RCIN. We are investigating the ratio of contrast dose to creatinine clearance (D/CrCL) as a risk indicator. Theory shows that the D/CrCL ratio equals the area under the concentration-time curve (AUC), an accepted measure of systemic exposure. This study investigated the correlation between calculated D/CrCL and experimentally measured AUC for the contrast agent iodixanol.

MATERIALS AND METHODS

Experimental data on AUC from a phase 1 study of iodixanol were plotted against the D/CrCL ratio and the degree of correlation was determined.

RESULTS

Experimentally determined AUC data correlate highly with the D/CrCL ratio.

CONCLUSIONS

The D/CrCL ratio is a rapid and accurate way to estimate AUC for an iodinated x-ray contrast agent without the need for multiple blood samples.

Acute renal failure associated with the use of traditional folk remedies in South Africa

The use of folk remedies is widespread throughout Africa. Acute renal failure (ARF) is one of the most severe, but under-recognized, complications of folk remedy use. This report aims to describe the clinical presentation, outcomes, and nature of renal injury in patients with folk-remedy-associated ARF. Clinical data were evaluated retrospectively in 78 patients with ARF associated with recent folk remedy use. ARF was defined as elevated serum urea and creatinine above the age-appropriate normal ranges, persistent oligoanuria, worsening renal function with time, or need for dialysis. Overall mortality in patients with ARF was 41%. Mortality was higher in adults (45.5%) than in infants (36.6%), in patients with both renal and liver dysfunction (62.5%) than in those with renal dysfunction alone (22.6%), and in HIV-positive (44.4%) versus HIV-negative (34.6%) patients. Vomiting (51.3%) and diarrhea (43.6%) were the most frequent presenting symptoms. Metabolic acidosis (80.8%) and volume depletion (62.8%) were the most frequent clinical findings. The definable causes of ARF were pre-renal (26.9%), acute tubular necrosis (ATN; 26.9%), hepatorenal syndrome (6.4%), urinary tract infection/sepsis (7.7%), and primary renal disorders (7.7%). Twenty-seven patients had concomitant medical conditions unlikely primarily related to folk remedy ingestion. In conclusion, ARF occurring after use of folk remedies in South Africa is associated with significant morbidity and mortality. The most common contributors to ARF in this setting are volume depletion and ATN. Significantly, although a proportion of patients have underlying systemic or renal conditions that may contribute to renal dysfunction, in the majority of patients, folk remedy use appears to be the most likely proximate cause. In view of the large numbers of Africans living abroad, more widespread awareness of this important clinical problem needs to be raised.

Acute renal insufficiency after high-dose melphalan in patients with primary systemic amyloidosis during stem cell transplantation

BACKGROUND

Patients with primary systemic amyloidosis (AL) have a poor prognosis. Median survival time from standard treatments is only 17 months. High-dose intravenous melphalan followed by peripheral blood stem cell transplant (PBSCT) appears to be the most promising therapy, but treatment mortality can be high. The authors have noted the development of acute renal insufficiency immediately after melphalan conditioning. This study was undertaken to further examine its risk factors and impact on posttransplant mortality.

METHODS

Consecutive AL patients who underwent PBSCT were studied retrospectively. Acute renal insufficiency (ARI) after high-dose melphalan was defined by a minimum increase of 0.5 mg/dL (44 micromol/L) in the serum creatinine level that is greater than 50% of baseline immediately after conditioning. Urine sediment score was the sum of the individual types of sediment identified on urine microscopy.

RESULTS

Of the 80 patients studied, ARI developed in 18.8% of the patients after high-dose melphalan. Univariate analysis identified age, hypoalbuminemia, heavy proteinuria, diuretic use, and urine sediment score (>3) as risk factors. Age and urine sediment score remained independently significant risk factors in the multivariate analysis. Patients who had ARI after high-dose melphalan underwent dialysis more often (P = 0.007), and had a worse 1-year survival (P = 0.03).

CONCLUSION

The timing of renal injury strongly suggests melphalan as the causative agent. Ongoing tubular injury may be a prerequisite for renal injury by melphalan as evidenced by the active urinary sediment. Development of ARI adversely affected the outcome after PBSCT. Effective preventive measures may help decrease the treatment mortality of PBSCT in AL patients.

Acute renal failure due to intrinsic renal diseases: review of 1122 cases

In this study we have analyzed incidence, causes and clinical course of ARF due to primary intrarenal disease other than acute tubular necrosis. Thousand hundred and twenty two cases of ARF of diverse etiology were studied over a period of 16 years; July 1984 to Dec, 1999. Surgical ARF 231 (20.6%) were not included in the present study. Intrinsic renal diseases were responsible for ARF in 891 (79.4%) of cases. The most common intrinsic renal diseases 705 (79.4%) causing ARF were ischemic/toxic acute tubular necrosis, but not included in this study. Acute renal failure was related to acute glomerulonephritis (9.3%), acute interstitial nephritis (7%), and renal cortical necrosis in (4.6%) of cases. Therefore intrinsic renal diseases other than ATN were the causative factor for acute renal failure in 186 (20.8%) patients in our study. Crescentic (51.8%) and endocapillary proliferative glomerulonephritis (34.9%), were the main glomerular diseases responsible for ARF and 75.9% of GN was related to infectious etiology. Fifty three percent of acute interstitial nephritis was drug induced and in 25 (40%) patients it was related to an infectious etiology. Renal cortical necrosis due to HUS was observed in 16 (39%) children and majority (76.47%) of the cases had a diarrhoeal prodrome. Obstetrical complications were the main causes (61%) of cortical necrosis in adults with acute renal failure. Thus, intrinsic renal diseases other than ATN were responsible for ARF in 186 (20.8%) cases. Post-infectious glomerulonephritis, acute interstitial nephritis and renal cortical necrosis (complicating HUS in children and obstetrical complications in adult) are the main causes of acute renal failure in our study. Both acute GN and interstitial nephritis had excellent prognosis, however renal cortical necrosis was associated with a very high mortality.

Worsening renal function: what is a clinically meaningful change in creatinine during hospitalization with heart failure?

INTRODUCTION

Worsening renal function during hospitalization for heart failure, defined as elevation in creatinine during admission, predicts adverse outcomes. Prior studies define worsening renal function using various creatinine elevations, but the relative value of definitions is unknown.

METHODS AND RESULTS

In a prospective cohort of 412 patients hospitalized for heart failure, we compared a spectrum of worsening renal function definitions (absolute creatinine elevations >/=0.1 to >/=0.5 mg/dL and 25% relative elevation from baseline) and associations with 6-month mortality, readmission, and functional decline. Creatinine elevation >/=0.1 mg/dL occurred in 75% of patients, and elevation >/=0.5 mg/dL occurred in 24% of patients. Risk of death rose with higher creatinine elevations (adjusted hazard ratio [HR] = 0.89, 1.19, 1.67, 1.91, and 2.90 for elevations >/=0.1 to >/=0.5 mg/dL). Maximum sensitivity of any definition for predicting mortality was 75% and maximum specificity was 79%. High creatinine elevation was a more important predictor of death than was a single measure of baseline creatinine.

CONCLUSIONS

Larger creatinine elevations predict highest risk of death, yet even minor changes in renal function are associated with adverse outcomes. The choice of a "best definition" for worsening renal function has implications for the number of patients identified with this risk factor and the magnitude of risk for mortality.

Herbal remedy-associated acute renal failure secondary to Cape aloes

Use of traditional herbal remedies is common in Africa, and many patients who visit traditional healers do not need to resort to Western medicine. Acute renal failure is one of the most serious complications resulting from the use of traditional remedies, however, which accounts for 35% of all cases of acute renal failure in Africa. Traditional remedies rarely have been analyzed, and little is known about their nephrotoxicity. We report a case of a 47-year-old man from Soweto, South Africa, who developed acute oliguric renal failure and liver dysfunction after ingestion of an herbal remedy. The patient's renal function recovered slowly, and dialysis was discontinued after several weeks, although serum creatinine did not return to the normal range. Mass spectrometric and chromatographic analysis of the herbal remedy used by the patient revealed the presence of Cape aloes, a previously described nephrotoxin.

Acute renal failure and dialysis in the chronically critically ill patient

Acute renal failure is a common clinical problem in the intensive care unit (ICU) and is associated with significant morbidity and mortality. There is no "magic bullet" to prevent acute renal failure or to modify the clinical course of established renal failure. The approach to therapy is directed to the early initiation of dialysis therapy. Continuous dialysis therapy is becoming the preferred form of dialysis in the ICU.

Frequency and outcome of patients with acute renal failure have more causes than one in etiology

In literature, there was little data about frequency and outcome of ARF with two or more causes in etiology. Therefore, the aim of this study was to search this issue. This series included 339 patients with ARF from Jan 1,1987 to Jan 1,1999. Fourty-six (30 males) of all patients (13.5%) had two or more causes in etiology of ARF. Of these patients, causes were prerenal and renal in 26 (56%), prerenal, renal and postrenal in 12 (26%), renal and postrenal in 4 (9%), and prerenal and postrenal in 4 (9%). The most frequent cause is diarrhea and vomiting in prerenal, gentamycin usage in renal and prostate hypertrophy in postrenal. Of these patients, there was oliguria in 32 (70%), anuria in 8 (17%) and non-oliguria in 6 (13%). Treatment modalities of patients was only medical in 19 (41%), dialysis in addition to medical therapy in 27 (59%). In spite of treatment, 5 (10.8) of patients with two or more causes in etiology died. Causes of death were uremic coma in 2, cardiac disorders in 2 and septic shock in 1. Three (11.2%) of other patients with one cause died. Mortality rates were not different (chi2: 0.0298, p > 0.5). Cortical necrosis was diagnosed in one patient with multiple etiology and 2 of other patients. Finally, frequency of ARF with two or more etiologic causes was 13.5%, and most frequent causes were hypovolemia and nephrotoxic drugs. Outcome of these patients was similar to other patients with one cause.

Correlates and impact on outcomes of worsening renal function in patients > or =65 years of age with heart failure

1.5 mg/dl. Based on the number of these factors, a patient's risk for developing worsening renal function ranged between 16% (< or =1 factor) and 53% (> or =5 factors). After adjusting for confounding effects, worsening renal function was associated with a significantly longer length of stay by 2.3 days, higher in-hospital cost by $1,758, and an increased risk of in-hospital mortality (odds ratio 2.72; 95% confidence interval 1.62 to 4.58). In conclusion, worsening renal function, an event that frequently occurs in elderly patients hospitalized with heart failure, confers a substantial burden to patients and the healthcare system and can be predicted by 6 admission characteristics.

An analysis of excess mortality not predicted to occur by APACHE III in an Australian level III intensive care unit

The APACHE III derived standardized mortality ratio has been suggested as a statistic to measure intensive care unit (ICU) effectiveness. From 1991 data collected on 519 consecutive admissions to the Royal Adelaide Hospital ICU a standardized mortality ratio of 1.25 was calculated. Of the 174 deaths only 95 had a prediction of death greater than 0.5. As part of a quality assurance study we undertook a retrospective case note audit to try to identify factors that were associated with the low mortality prediction (< 0.5) in hospital deaths. Firstly we analysed the patient population that died to determine the factors that were different between patients who had a mortality prediction of greater than 0.5 versus those who had a mortality prediction of less than 0.5. Next we analysed the patient population with a mortality prediction of less than 0.5 and compared actual survivors with patients who died in hospital. Amongst low mortality prediction patients admitted to the Royal Adelaide Hospital ICU we identified age, a history of acute myocardial infarction, presentation to ICU after a cardiac arrest or with an elevated creatinine and the development of acute renal failure and septicaemia during the ICU admission as being associated with in-hospital mortality. We also documented that late hospital deaths on the ward after ICU discharge occurred more frequently with low predicted hospital mortality ICU patients. Factors other than the APACHE III score may be associated with hospital deaths of ICU patients.

Oxygen and renal hemodynamics in the conscious rat

Previous studies have suggested a link between renal metabolism and local kidney hemodynamics to prevent potential hypoxic injury of particularly vulnerable nephron segments, such as the outer medullary region. The present study used three different inspiratory oxygen concentrations to modify renal metabolic state in the conscious rat (hypoxia 10% O2, normoxia 20% 02, and hyperoxia 100% 02). Renal blood flow (RBF) was assessed by ultrasound transit time; renal perfusion pressure (RPP) was controlled by a hydroelectric servo-control device. Local RBF was estimated by laser-Doppler flux for the cortical and outer medullary region (2 and 4 mm below renal surface, respectively). Hypoxia led to a generalized significant increase in RBF, whereas hyperoxia-induced changes did not (hypoxia 6.6 +/- 0.6 ml/min versus normoxia 5.7 +/- 0.7 ml/min, P < 0.05). Moreover, regional and total RBF autoregulation was markedly attenuated by hypoxia. Conversely, hyperoxia enhanced RBF autoregulation. Under normoxic and hyperoxic conditions, medullary RBF was very well maintained, even at low RPP (medullary RBF: approximately 70% of control at 50 mmHg). The hypoxic challenge, however, significantly diminished the capacity to maintain medullary blood flow at low RPP (medullary RBF: approximately 30% of control at 50 mmHg, P < 0.05). These data suggest that renal metabolism and renal hemodynamics are closely intertwined. In response to acute hypoperfusion, the kidney succeeds in maintaining remarkably high medullary blood flow. This is not accomplished, however, when a concomitant hypoxic challenge is superimposed on RPP reduction.

Prediction of mortality in patients with bacteremia: the importance of pre-existing renal insufficiency

Pre-existing renal insufficiency serves as a common risk factor in the development of acute renal failure. Acute renal failure is a common finding in patients with bacteremia and is associated with poor prognosis. A total of 2722 consecutive patients 18 years old or older, fulfilling strike criteria of bacteremia or fungemia were prospectively evaluated to establish the prognostic importance of pre-existing renal insufficiency in bacteremic patients. They were classified according to serum creatinine levels upon admission into three groups. 915 patients had normal creatinine levels (< or = 1.0 mg/dL), 1528 had mild to moderate renal failure (creatinine 1.1-3 mg/dL) and 279 patients had severe renal failure upon admission (creatinine > 3.0 mg/dL). Mild to severe renal failure upon admission was associated with old age, male gender, diabetes mellitus, ischemic heat disease, hypertension and congestive heart failure. The serum albumin in patients with severe renal failure was significantly low, with a mean of 2-9 mg/dL. Urinary tract infections were more prevalent in patients with mild to severe renal failure, while intravenous line infections, bacterial endocarditis and soft and skin tissue infections were more common in patients with normal renal function. In the 279 patients with severe renal failure the mortality rate was significantly higher (50%) compared to patents with mild to moderate renal failure and patients with normal renal function (21% and 26% respectively, p = 0.0001). Multiple regression analysis revealed that pre-existing serum creatinine > 3 mg/dL was significantly associated with death attributable to bacteremia (OR = 1.7, 95% CI 1.0-2.7). In conclusion, adult bacteremic patients with pre-existing serum creatinine above 3 mg/dL upon admission are at increased risk of mortality due to bacteremia than patients with normal or mild to moderate renal failure.

Prognosis in acute renal failure of septic origin: a multivariate analysis

The goal of the present study was to identify variables associated with the outcome of patients with acute renal failure (ARF) of septic origin, using multivariate analysis. The records of 168 patients were reviewed retrospectively and a crude mortality of 74% was found. Both univariate as well as multivariate analysis demonstrated an association between mortality and variables which depended on patient related factors. These included age over 60 years and several underlying diseases such as pneumonia, peritonitis, and organ dysfunction. Only one variable (late oliguria) related to the ARF itself. Thus, outcome seems related to underlying disease more than to severity of ARF.

The differential induction of two immediate early genes, c-fos and c-jun, after systemic hypovolemic shock/resuscitation in the rat liver and kidney

The aim of this study was to investigate the expression of the immediate early genes (IEGs), c-fos and c-jun, in the rat kidney and liver in two types of hemorrhage shock/resuscitation models. In the first group, hemorrhagic shock was induced by the withdrawal of blood through the carotid artery. A mean arterial blood pressure (MAP) of 40mmHg was maintained for 1h before blood was reperfused. In the second group, the MAP was maintained at the same level for 2h. Animals were resuscitated with Ringer's lactate solution. In the first group, a rapid and transient induction of c-fos and c-jun mRNAs in both the liver and kidney was observed, peaking 0 to 2 h after reperfusion. In the second group, a more protracted pattern of induction was evident in both organs. In both models, the induction of c-fos mRNA was distinctly different in the liver and kidney. These results indicated, first, that with respect to IEG expression, organs respond differently to a systemic shock/resuscitation stimuli, and second, that alterations in the pattern of IEG expression might represent an indication of the degree of organ damage or the repair processes subsequent to hypotension/reperfusion.

A simple and early prognostic index for acute renal failure patients requiring renal replacement therapy

Recent advances in technology have not substantially changed the high mortality rate associated with acute renal failure (ARF). To obtain a simple, valid prognostic index, we retrospectively evaluated the relative importance of demographic data, causes (acute insults) of renal failure, and comorbid clinical conditions for the outcome in 102 ARF patients who received renal replacement therapy with an overall mortality rate of 65% (66 of 102). There were no significant differences between survivors and nonsurvivors in age and gender. Mortality according to acute insults was similar to that of the whole population studied. Of the 10 clinical conditions at the time of the first renal replacement therapy, mechanical ventilation (p = 0.0002), cardiac failure (p = 0.0006), hepatic failure (p = 0.003), central nervous system dysfunction (p = 0.005), and oliguria (p = 0.04) were found to be significantly related to mortality by univariate analysis. Furthermore, multivariate analysis demonstrated that only mechanical ventilation, cardiac failure, and hepatic failure were significant risk factors. Survival was directly related to the number of significant variables in univariate analysis: zero, 89% (8 of 9); one, 62% (21 of 34); two, 19% (5 of 27); three, 10% (2 of 20); four, 0% (0 of 8); five, 0% (0 of 4). This simple and early prognostic index, derived from the assessment of clinical conditions which were easily determined at the patient's bedside, could be useful for outcome prediction in ARF patients requiring renal replacement therapy.

Fatal rhabdomyolysis in a flame burn patient

Rhabdomyolysis due to flame burns is not well described. A case of fatal rhabdomyolysis in an epileptic patient who sustained 65 per cent body surface area, very deep, flame burns is described. It appears as if the sustained muscle compression from the restrictive, circumferential eschar was the major factor in the aetiology of the rhabdomyolysis. Despite aggressive fluid management, the patient died of acute renal failure and adult respiratory distress syndrome. We have subsequently identified three other cases of pigmenturia occurring following burns. It would seem as if rhabdomyolysis following extensive full thickness burns may be more common than previously suggested. Fluid requirements are in excess of those proposed by traditional protocols. Rhabdomyolysis in flame burn patients indicates a poor prognosis.

Does vancomycine increase aminoglycoside nephrotoxicity?

Vancomycine and amikacin combined is an effective antibiotic combination used in the treatment of serious Gram-positive bacteremia in childhood. However, both drugs may have a potential nephrotoxic effect when used individually. The present study investigates whether the nephrotoxicity of these drugs that display a nephrotoxic effect when used separately increases when used in a combined manner. Ten 2-month-old rats were subjected to intraperitoneal injections of vancomycine (100 mg/kg) and amikacin (80 mg/kg) and ten other 2-month-old rats were administered amikacin (80 mg/kg) for a period of 15 days. The control group of animals consisting of five 2-month old rats were untreated. The renal tissues obtained by laparotomy were processed for both light and electron microscopy. Paraffin sections and ultrathin sections were evaluated in order to determine the renal structure of the control and the experimental groups. In addition, serum creatinine and blood, urea and nitrogen (BUN) levels were measured in blood samples obtained from the rats. In the amikacin and combined amikacin-vancomycine treatment groups, renal morphological changes were observed at the glomerular and tubular levels when compared to the control group, and the serum creatinine and BUN levels were also higher in these groups. Although both experimental groups were different from the control group, they had similar morphological and biochemical features. It was concluded that vancomycine did not influence the nephrotoxic effect of amikacin and both drugs could be used in a combined manner.

Renal vascular responses to high and low ionized calcium: influence of norepinephrine in the isolated perfused rat kidney

OBJECTIVE AND DESIGN

The aim of this study was to examine the influence of norepinephrine (NE) on renal vascular responses to high (1.88 mmol/L) and low (0.56 mmol/L) perfusate-ionized calcium ([Ca2+]) in the isolated perfused kidney of the rat. High and low [Ca2+] encompassed the clinical concentration range in this multiexperiment, randomized trial.

MATERIALS AND METHODS

Rats (n = 25), ranging in age from 3 to 4 months, were anesthetized and the ureter and renal artery were cannulated. The right kidney was perfused with oxygenated, warmed albumin (67 g/L) containing Krebs-Henseleit buffer and placed in a thermostated chamber without interruption of flow. In protocol A (n = 7), steady-state high [Ca2+] (1.88 mmol/L) and low [Ca2+] (0.56 mmol/L) were instituted in randomized order in each experiment under basal conditions. In protocol B (n = 9), the same interventions were instituted during constant rate NE infusion. Changes in renal flow were measured at constant perfusion pressure (110 mm Hg), and renal vascular resistance (RVR) was calculated. Renal function was assessed by clearance of [14C]inulin and by fractional excretion of sodium. With NE-induced preconstriction, the increase in RVR observed during high [Ca2+] was +17.8 +/- 1.8% of control, and the decrease in RVR observed during low [Ca2+] was -35.9 +/- 8.2% of control. Both values were greater by a factor of 2 than corresponding results obtained under basal conditions (7 +/- 2.1% vs. -13.5 +/- 4.1% of control, respectively, p < 0.05). Whereas the decrease in glomerular filtration rate with high [Ca2+] was not significantly influenced by NE pretreatment (-9 +/- 1.8% of control with high [Ca2+] in combination with NE vs. 4.1 +/- 0.7% of control under basal conditions), the increase in glomerular filtration rate with low [Ca2+] was significantly greater in the presence of NE (12 +/- 0.7 vs. 102 +/- 8.5% of control, p < 0.01).

CONCLUSIONS

Whereas under basal conditions renal vascular effects of high and low [Ca2+] (varied within the clinical concentration range) are small, the changes recorded with the same interventions after NE pretreatment are increased by a factor of > 2. Hypercalcemia-induced renovascular constriction and decreased function are unfavorable, especially in patients who are at risk for renal dysfunction from other causes.