Acute renal failure and the critically ill surgical patient

Risk factors and outcomes regarding the acute kidney injury after AngioJet thrombectomy for acute lower-extremity deep vein thrombosis

OBJECTIVE

To investigate the risk factors and outcomes regarding acute kidney injury (AKI) after AngioJet thrombectomy for acute lower-extremity deep vein thrombosis (DVT).

METHODS

Patients were divided into AKI and non-AKI groups according to whether AKI occurred postoperatively. The demographic data, pre-operative and post-operative laboratory data and surgical differences were compared between the two groups. Logistic regression and Wilcoxon signed-rank test were used to identify the AKI risk factors and outcomes, respectively.

RESULTS

Among the 341 patients who met the inclusion criteria, 45 developed AKI (AKI group) and 296 had normal renal function (non-AKI group) post-surgery. There were significant differences between the two groups in the course (t = 10.885, P = 0.000); preoperative history of a major surgery within 3 months (3M-MS) (odds ratio [OR] = 5.492, P = 0.001); duration of aspiration thrombectomy (Z = -8.803, P = 0.000); volumes of aspiration (Z = -8.215, P = 0.000); contrast volume (Z = -3.204, P = 0.001) and pulmonary thrombectomy (OR = 18.200, P = 0.002); and preoperative complications of hypertension (OR = 4.637, P = 0.002), diabetes (OR = 18.088, P = 0.000), or pulmonary embolism (OR = 0.085, P = 0.011). Wilcoxon signed-rank test showed that the renal function of every patient in the AKI group returned to normal 3 months after the surgery.

CONCLUSIONS

The course, preoperative complications of diabetes or hypertension, 3M-MS, contrast volume, duration and volume of aspiration thrombectomy, and pulmonary thrombectomy are risk factors for post-AngioJet-thrombectomy AKI, which is temporary.

Palliative Care for Patients with Kidney Disease

Interest in palliative care has increased in recent times, particularly in its multidisciplinary approach developed to meet the needs of patients with a life-threatening disease and their families. Although the modern concept of palliative simultaneous care postulates the adoption of these qualitative treatments early on during the life-threatening disease (and potentially just after the diagnosis), palliative care is still reserved for patients at the end of their life in most of the clinical realities, and thus is consequently mistaken for hospice care. Patients with acute or chronic kidney disease (CKD) usually experience poor quality of life and decreased survival expectancy and thus may benefit from palliative care. Palliative care requires close collaboration among multiple health care providers, patients, and their families to share the diagnosis, prognosis, realistic treatment goals, and treatment decisions. Several approaches, such as conservative management, extracorporeal, and peritoneal palliative dialysis, can be attempted to globally meet the needs of patients with kidney disease (e.g., physical, social, psychological, or spiritual needs). Particularly for frail patients, pharmacologic management or peritoneal dialysis may be more appropriate than extracorporeal treatment. Extracorporeal dialysis treatment may be disproportionate in these patients and associated with a high burden of symptoms correlated with this invasive procedure. For those patients undergoing extracorporeal dialysis, individualized goal setting and a broader concept of adequacy should be considered as the foundations of extracorporeal palliative dialysis. Interestingly, little evidence is available on palliative and end of life care for acute kidney injury (AKI) patients. In this review, the main variables influencing medical decision-making about palliative care in patients with kidney disease are described, as well as the different approaches that can fulfill the needs of patients with CKD and AKI.

Renal denervation alleviates renal ischemic reperfusion injury-induced acute and chronic kidney injury in rats partly by modulating miRNAs

BACKGROUND

Renal denervation (RDN) has been used to promote kidney injury repair, whereas miRNAs have been found to be involved in the pathophysiology of renal injury. However, the miRNA alterations that occur after RDN and the related protective mechanisms remain to be determined.

METHODS

Renal ischemic reperfusion injury (IRI) rat model was established and RDN was performed. Animals were killed at 24 h and 2 weeks following the operation. Tyrosine hydroxylase (TH) levels, renal function, tubular cell apoptosis and histological sections were examined at 24 h, whereas renal fibrosis and capillary vessels were assessed at 2 weeks. Furthermore, the expression of miRNAs in the injured kidney was determined using micro-array and the target genes were analyzed.

RESULTS

We found that TH was eliminated and that renal function was improved in the denervation group at 24 h. RDN reduced tubular cell apoptosis and mitigated the histological lesion. Furthermore, an increase of capillary vessel density and reduction of renal fibrosis were observed after 2 weeks. Moreover, the numbers of miRNAs were up-regulated after RDN treatment, and the miRNAs targeted pro-angiogenic, anti-fibrotic and inflammatory pathways.

CONCLUSIONS

RDN is a reliable method for alleviating IRI-induced acute and chronic kidney injury, and modulating the miRNA-related pro-angiogenic, anti-fibrotic or inflammatory pathways involved in this process.

Obese trauma patients have increased need for dialysis

PURPOSE

Obesity is a risk factor for the development of acute kidney injury but its effect on the need for dialysis in trauma has not been elucidated. Additionally, the contribution that obesity has towards risk of mortality in trauma is unclear. We hypothesized that patients with a higher body mass index (BMI) will have a higher risk for need of dialysis and mortality after trauma.

METHODS

This is a retrospective analysis using the National Trauma Data Bank. All patients ≥ 8 years old were grouped based on BMI: normal (18.5-24.99 kg/m²), obese (30-34.99 kg/m²), severely obese (35-39.99 kg/m²) and morbidly obese (≥ 40 kg/m²). The primary outcome was hemodialysis initiation. The secondary outcome was mortality during the index hospitalization.

RESULTS

From 988,988 trauma patients, 571,507 (57.8%) had a normal BMI, 233,340 (23.6%) were obese, 94,708 (9.6%) were severely obese, and 89,433 (9.0%) were morbidly obese. The overall rate of hemodialysis was 0.3%. After adjusting for covariates, we found that obese (OR 1.36, CI 1.22-1.52, p < 0.001), severely obese (OR 1.89, CI 1.66-2.15, p < 0.001) and morbidly obese (OR 2.04, CI 1.82-2.29, p < 0.001) patients had a stepwise increased need for hemodialysis after trauma. Obese patients had decreased (OR 0.92, CI 0.88-0.95, p < 0.001), severely obese had similar (OR 1.02, CI 0.97-1.08, p = 0.50) and morbidly obese patients had increased (OR 1.06, CI 1.01-1.12, p = 0.011) risk of mortality after trauma.

CONCLUSIONS

Obesity was associated with an increased risk for dialysis after trauma. Mortality risk was reduced in obese, similar in severely obese, and increased in morbidly obese trauma patients suggesting an inflection threshold BMI for risk of mortality in trauma.

Creatinine, Neutrophil Gelatinase-Associated Lipocalin, and Cystatin C in Determining Acute Kidney Injury After Heart Operations Using Cardiopulmonary Bypass

Acute kidney injury (AKI) represents frequent complication after cardiac surgery using cardiopulmonary bypass (CPB). In the hope to enhance earlier more reliable characterization of AKI, we tested the utility of neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C (CysC) in addition to standard creatinine for early determination of AKI after cardiac surgery using CPB. Forty-one patients met the inclusion criteria. Arterial blood samples collected after induction of general anesthesia were used as baseline, further sampling occurred at CPB termination, 2 h after CPB, on the first and second day after surgery. According to AKIN classification 18 patients (44%) developed AKI (AKI1-2 groups) and 23 (56%) did not (non-AKI group). Groups were similar regarding demographics and operative characteristics. CysC levels differed already preoperatively (non-AKI vs. AKI2; P = 0.045; AKI1 vs. AKI2; P = 0.011), while postoperatively AKI2 group differed on the first day and AKI1 on the second regarding non-AKI group (P = 0.004; P = 0.021, respectively). NGAL and creatinine showed significant difference already 2 h after CPB between groups AKI2 and non-AKI and later on the first postoperative day between groups AKI1 and AKI2 (P = 0.028; P = 0.014, respectively). This study shows similar performance of early plasma creatinine and NGAL in patients with preserved preoperative renal function. It demonstrates that creatinine, as well as NGAL, differentiate subsets of patients developing AKI of clinically more advanced grade early after 2 h, also when used single and uncombined.

Intrauterine growth restriction modifies the normal gene expression in kidney from rabbit fetuses

The aim of this work was to study the effect of intrauterine growth restriction (IUGR) on fetal kidneys. The IUGR was induced by uteroplacental vessels ligature in a model of pregnant rabbit. We centralized the study in the gene expression of essential proteins for fetal kidney development and kidney protection against hypoxia, osmotic stress, and kidney injury. The gene expression of HIF-1α, NFAT5, IL-1β, NGAL, and ATM were studied by qRT-PCR and Western blot in kidneys from control and IUGR fetuses. Experimental IUGR fetuses were significantly smaller than the control animals (39 vs. 48 g, p<0.05). The number of glomeruli was decreased in IUGR kidneys, without morphological alterations. IUGR increased the gene expression of HIF-1α, NFAT5, IL-1β, NGAL, and ATM (p<0.05) in kidneys of fetuses undergoing IUGR, suggesting that fetal blood flow restriction produce alterations in gene expression in fetal kidneys.

Decreased urine output and acute kidney injury in the postanesthesia care unit

Decreased urine output and acute kidney injury (also known as acute renal failure) are among the most important complications that may develop in the postanesthetic period. In this article, the authors present definitions of decreased urine output, oliguria, and acute kidney injury. They review the epidemiology, pathophysiology, and prevention of postoperative acute kidney injury. Finally, the article offers approaches to diagnosis and management of the postsurgical patient with decreased urine output or acute kidney injury.

NFAT5 is activated by hypoxia: role in ischemia and reperfusion in the rat kidney

The current hypothesis postulates that NFAT5 activation in the kidney's inner medulla is due to hypertonicity, resulting in cell protection. Additionally, the renal medulla is hypoxic (10–18 mmHg); however there is no information about the effect of hypoxia on NFAT5. Using in vivo and in vitro models, we evaluated the effect of reducing the partial pressure of oxygen (PO₂) on NFAT5 activity. We found that 1) Anoxia increased NFAT5 expression and nuclear translocation in primary cultures of IMCD cells from rat kidney. 2) Anoxia increased transcriptional activity and nuclear translocation of NFAT5 in HEK293 cells. 3) The dose-response curve demonstrated that HIF-1α peaked at 2.5% and NFAT5 at 1% of O₂. 4) At 2.5% of O₂, the time-course curve of hypoxia demonstrated earlier induction of HIF-1α gene expression than NFAT5. 5) siRNA knockdown of NFAT5 increased the hypoxia-induced cell death. 6) siRNA knockdown of HIF-1α did not affect the NFAT5 induction by hypoxia. Additionally, HIF-1α was still induced by hypoxia even when NFAT5 was knocked down. 7) NFAT5 and HIF-1α expression were increased in kidney (cortex and medulla) from rats subjected to an experimental model of ischemia and reperfusion (I/R). 7) Experimental I/R increased the NFAT5-target gene aldose reductase (AR). 8) NFAT5 activators (ATM and PI3K) were induced in vitro (HEK293 cells) and in vivo (I/R kidneys) with the same timing of NFAT5. 8) Wortmannin, which inhibits ATM and PI3K, reduces hypoxia-induced NFAT5 transcriptional activation in HEK293 cells. These results demonstrate for the first time that NFAT5 is induced by hypoxia and could be a protective factor against ischemic damage.

Tidal versus other forms of peritoneal dialysis for acute kidney injury

BACKGROUND

Acute kidney injury (AKI) is associated with substantial morbidity and mortality. Recent studies have shown that dialysis dose was a major factor associated with patient survival. Unresolved questions persist about which mode of peritoneal dialysis (PD) should be used for most patients with AKI.

OBJECTIVES

To assess the benefits and harms of tidal PD (TPD) versus other forms of PD on outcomes for patients with AKI.

SEARCH METHODS

In February 2012 we searched the Cochrane Renal Group's specialised register, CENTRAL (in The Cochrane Library), MEDLINE (from 1966) and EMBASE (from 1980). We also searched reference lists of included studies, review articles and nephrology text books, and contacted local and international experts.

SELECTION CRITERIA

All randomised controlled trials (RCTs) and quasi-RCTs (RCTs in which allocation to treatment was obtained by alternation, use of alternate medical records, date of birth or other predictable methods) of TPD versus other forms of PD for AKI.

DATA COLLECTION AND ANALYSIS

Two authors independently reviewed search results, extracted data and assessed risk of bias. Results were expressed as risk ratios (RR) with 95% confidence intervals (CI) for dichotomous outcomes and mean difference (MD) for continuous outcomes using a random-effects model.

MAIN RESULTS

We included one randomised cross-over study, enrolling 87 participants, which compared TPD with continuous equilibrating PD (CEPD) for patients with AKI. Sequence generation was adequate while allocation concealment was not reported. Our primary outcomes of mortality and recovery of renal function (complete or partial) were not reported (high risk of selective reporting bias). The results from this one study showed TPD resulted in higher creatinine clearance (CrCl) (MD 1.88 mL/min, 95% CI 0.91 to 2.85) and blood urea nitrogen (BUN) clearance (MD 14.71 mL/min, 95% CI 8.24 to 21.18) than CEPD; was superior to CEPD in the removal of potassium, phosphates and in generating ultrafiltrate; was better tolerated; consumed less time and was less expensive than CEPD. There was greater protein loss with TPD. No adverse events were reported.

AUTHORS' CONCLUSIONS

At present, there is insufficient RCT evidence to enable evaluation of the effect of TPD in patients with AKI. Well-designed and larger RCTs are required to better understand the risks and benefits of TPD for AKI.

Acute kidney injury with renal replacement therapy in trauma patients

BACKGROUND

Acute kidney injury (AKI) with renal replacement therapy (RRT) is rare in trauma patients. The primary aim of the study was to assess incidence, mortality and chronic RRT dependency in this patient group.

METHODS

Adult trauma patients with AKI receiving RRT at a regional trauma referral center over a 12-year period were retrospectively reviewed.

RESULTS

Population-based incidence of post-traumatic AKI with RRT was 1.8 persons per million inhabitants per year (p.p.m./year) [95% confidence the interval (CI) 1.5-2.1 p.p.m./year]. In trauma patients admitted to hospital, incidence was 0.5 per thousand (95% CI 0.3-0.7 per thousand) of those treated in intensive care unit (ICU), it was 8.3% (95% CI 5.9-10.8%). The median age was 46 years. Odds ratio (OR) for post-traumatic AKI requiring RRT was higher in males than in females in general population (OR 5.6, 95% CI 2.2-14.0), and in trauma patients admitted to hospital (OR 4.4, 95% CI 1.9-10.3) and ICU (OR 4.5, 95% CI 1.9-10.7). The in-hospital mortality rate was 24% (95% CI 11-37%), 3-month mortality 36% (95% CI 21-51%) and 1-year mortality 40% (95% CI 25-55%). Age was a risk factor for death after 1 year, with 57% (95% CI 7-109%) increased risk for each 10 years added. None of the survivors was dialysis-dependent 3 months or 1 year after trauma.

CONCLUSION

AKI in trauma patients requiring RRT was rare in this single-center study. More males than females were affected. Mortality was modest, and renal recovery was excellent as none of the survivors became dependent on chronic RRT.

Diabetes, insulin, and development of acute lung injury

OBJECTIVES

Recently, many studies have investigated the immunomodulatory effects of insulin and glucose control in critical illness. This review examines evidence regarding the relationship between diabetes and the development of acute lung injury/acute respiratory distress syndrome (ALI/ARDS), reviews studies of lung injury related to glycemic and nonglycemic metabolic features of diabetes, and examines the effect of diabetic therapies.

DATA SOURCES AND STUDY SELECTION

A MEDLINE/PubMed search from inception to August 1, 2008, was conducted using the search terms acute lung injury, acute respiratory distress syndrome, hyperglycemia, diabetes mellitus, insulin, hydroxymethylglutaryl-CoA reductase inhibitors (statins), angiotensin-converting enzyme inhibitor, and peroxisome proliferator-activated receptors, including combinations of these terms. Bibliographies of retrieved articles were manually reviewed.

DATA EXTRACTION AND SYNTHESIS

Available studies were critically reviewed, and data were extracted with special attention to the human and animal studies that explored a) diabetes and ALI; b) hyperglycemia and ALI; c) metabolic nonhyperglycemic features of diabetes and ALI; and d) diabetic therapies and ALI.

CONCLUSIONS

Clinical and experimental data indicate that diabetes is protective against the development of ALI/ARDS. The pathways involved are complex and likely include effects of hyperglycemia on the inflammatory response, metabolic abnormalities in diabetes, and the interactions of therapeutic agents given to diabetic patients. Multidisciplinary, multifaceted studies, involving both animal models and clinical and molecular epidemiology techniques, are essential.