Acute renal failure in the critically ill patient

Efficacy Evaluation and Tracking of Bone Marrow Stromal Stem Cells in a Rat Model of Renal Ischemia-Reperfusion Injury

Objectives

The aim of this study was to evaluate the effects of bone marrow stromal stem cells (BMSCs) on renal ischemia-reperfusion injury (RIRI) and dynamically monitor engrafted BMSCs in vivo for the early prediction of their therapeutic effects in a rat model.

Methods

A rat model of RIRI was prepared by clamping the left renal artery for 45 min. One week after renal artery clamping, 2 × 10⁶ superparamagnetic iron oxide- (SPIO-) labeled BMSCs were injected into the renal artery. Next, MR imaging of the kidneys was performed on days 1, 7, 14, and 21 after cell transplantation. On day 21, after transplantation, serum creatinine (Scr) and urea nitrogen (BUN) levels were assessed, and HE staining and TUNEL assay were also performed.

Results

The body weight growth rates in the SPIO-BMSC group were significantly higher than those in the PBS group (P < 0.05), and the Scr and BUN levels were also significantly lower than those in the PBS group (P < 0.05). HE staining showed that the degree of degeneration and vacuole-like changes in the renal tubular epithelial cells in the SPIO-BMSC group was significantly better than that observed in the PBS group. The TUNEL assay showed that the number of apoptotic renal tubular epithelial cells in the SPIO-BMSC group was significantly lower than that in the PBS group. The T2 value of the renal lesion was the highest on day 1 after cell transplantation, and it gradually decreased with time in both the PBS and SPIO-BMSC groups but was always the lowest in the SPIO-BMSC group.

Conclusion

SPIO-labeled BMSC transplantation can significantly promote the recovery of RIRI and noninvasive dynamic monitoring of engrafted cells and can also be performed simultaneously with MRI in vivo for the early prediction of therapeutic effects.

Outcomes of hospital-acquired acute kidney injury in elderly patients: a single-centre study

BACKGROUND

HAAKI is a common clinical problem in hospitalized patients. Its incidence is high in older patients and carries worse prognosis. The presence of multiple co-morbidities, aging process, and frequent diagnostic and therapeutic interventions predispose elderly patients to HAAKI. This study aims to evaluate the spectrum, risk factors and determinants of outcome of elderly patients with HAAKI.

METHODS

This prospective study was conducted during January 2014 to September 2015 in the Department of nephrology, Institute of Medical Sciences, BHU, Varanasi, UP, India. First 100 HAAKI elderly (> 60 years) patients, who fulfilled the inclusion criteria were enrolled for study. HAAKI was defined as per RIFLE criteria after minimum 48 h of hospitalization. Clinical, biochemical, and radiological evaluation were done. Follow up was done till discharge or up to 30 days whichever was later.

RESULTS

Till selection and enrollment of first 100 HAAKI patients, total 23507 patients were hospitalized. 11.2% (n = 2635) patients were ≥ 60 years of age. Among 2635 elderly patients, 3.79% (n = 100) developed HAAKI. Commonest causes of HAAKI were sepsis (37%) followed by drugs like NSAID, Contrast agent, Amphotericin B, and antibiotics including amino glycosides in (24%) patents. DM and HTN were the commonest risk factors. Mortality was noted in 45% cases and rest 55% patients recovered with partial or full recovery of renal function. ICU admission, Oliguria, RIFLE-F, need of RRT, and SOFA score > 11 were independent determinants of outcome of elderly patients with HAAKI.

CONCLUSION

HAAKI is associated with increased morbidity and mortality in elderly patients. Associated co-morbid conditions predispose elderly patients to HAAKI. ICU admission, Oliguria, severity of renal failure, requirement of RRT, and initial SOFA score were strong predictors of survival of elderly patients with HAAKI.

Adipose-derived mesenchymal stem cells therapy for acute kidney injury induced by ischemia-reperfusion in a rat model

Acute kidney injury (AKI) represents a group of complicated syndromes with a high mortality rate. The administration of adipose-derived mesenchymal stem cells (ADMSCs) has been tested as a possible treatment method for AKI. The long-term evaluation of AKI induced by ischemia/reperfusion (IR) and the probable renal protection of ADMSCs are limited. In this study we have established a rat AKI model induced by IR and investigated the possible protective effects of ADMSCs. Adult Sprague-Dawley (SD) rats were divided into three groups (n = 6/each group). The MOCK group was as the normal control. Rats in the IR-AKI and IR-AKI+ADMSCs groups were subjected to IR injury by clamping both renal pedicles for 40 minutes. Rats in the MOCK and IR-AKI groups were injected with PBS via the tail vein as negative treatment controls. Rats in the IR-AKI+ADMSCs group received ADMSCs therapy (2 × 10⁶ cells were injected into the rats via the tail vein). We found that ADMSC transplantation restored the pathologic morphology induced by IR-AKI to normal compared with the MOCK group, suggesting the reparative function of ADMSCs in kidney tissues. Compared with IR-induced AKI alone, ADMSC treatment significantly decreased the number of apoptotic cells, the level of total urinary protein and serum creatinine, the expression of pro-inflammatory cytokines (IL-6, TNF-α, IL-1β, IFN-γ, TNF-α, IFN-γ, and TGF-β), and the inflammation-associated proteins (HGF and SDF1), but increased the expression of the anti-inflammatory cytokine, IL-10, and the anti-apoptotic regulator, Bcl-2. Our data have indicated that ADMSC transplantation may protect against IR-induced AKI by anti-apoptotic and anti-inflammatory effects.

Renal-Dose Dopamine: From Hypothesis to Paradigm to Dogma to Myth and, Finally, Superstition?

Acute renal failure (ARF) is common in the critically ill and is associated with a high mortality rate. Its pathogenesis is not understood. Because animal models use ischemia to induce experimental ARF, there is the widespread belief that lack of blood flow is responsible for ARF. Low-dose dopamine (LDD) has been shown to increase renal blood flow in animal and in human volunteers. Thus, it has been administered to humans for almost 3 decades in the belief that it would lead to renal arterial vasodilation and increase renal blood flow (RBF). However, the etiology of ARF in critical illness is likely multifactorial, and the contribution of hypovolemia and reduced renal perfusion is unknown. Furthermore, interindividual variation in the pharmacokinetics of dopamine typically results in poor correlation between blood levels and administered dose, making accurate and reliable delivery of LDD difficult. Finally, dopamine is a proximal tubular diuretic that increases Na+ delivery to tubular cells, thus increasing their oxygen demands. Accordingly, even if LDD were able to preferentially increase RBF, there is no guarantee that it would restore renal parenchymal oxygen homeostasis. More important, 2 meta-analyses and a large double-blind, prospective, multiple-center, randomized controlled trial have failed to demonstrate that dopamine protects the kidney in critically ill patients with ARF. Currently, there is insufficient evidence to support the use of renal-dose dopamine in the intensive care unit.

Preventive Role of Endothelin Antagonist on Kidney Ischemia: Reperfusion Injury in Male and Female Rats

Background:

Renal ischemia/reperfusion injury (RIRI) is the most common cause of acute kidney injury. We tested the protective role of endothelin-1 receptor blocker; bosentan (BOS) in animal model of RIRI in two different genders.

Methods:

Male and female Wistar rats were assigned as sham operated (sham), control group (ischemia), and case group (ischemia + BOS) treated with BOS (50 mg/kg) 2 h before bilateral kidney ischemia induced by clamping renal vessels for 45 min followed by 24 h of renal reperfusion.

Results:

The RIRI significantly increased the serum levels of blood urea nitrogen and creatinine in both genders (P < 0.05). These values were significantly decreased by BOS in both genders. In male rats, the serum levels of malondialdehyde in the ischemia + BOS group were decreased significantly when compared with ischemia group (P < 0.05).

Conclusions:

BOS can be used in both genders to attenuate kidney ischemia injury possibly due to its effect in the renal vascular system.

Importance of neutrophil gelatinase-associated lipocalin in differential diagnosis of acute and chronic renal failure

Background:

Neutrophil Gelatinase-associated Lipocalin (NGAL) protein is easily detected in the blood and urine soon after acute renal injury. NGAL gains features of an early, sensitive and noninvasive biomarker for acute renal injury. Recent evidences suggest that its expression is also increased in CRF reflecting the severity of disease.

Objectives:

In the present study, we aimed to investigate whether blood NGAL level plays a role in the differential diagnosis of acute and chronic renal failure.

Patients and Methods:

This was a prospective case-control study. Fifty patients presented to emergency department with acute renal failure (ARF), 30 with chronic renal failure (CRF) and 20 healthy individuals as control group were included in this study. Blood pH, HCO3^-, BUN, creatinine and potassium values were evaluated in all patients. Blood NGAL values were evaluated in all groups. BUN, serum creatinine and NGAL values were statistically compared between patients and controls.

Results:

Median NGAL levels in patients was 304.50 (29), and 60 (0) in control, which was statistically significant between the two groups (Z = -6.477, P < 0.001). The median NGAL values were 261.50 ± 291 in ARF group and 428.50 ± 294 in CRF group. There was a significant difference in NGAL level between ARF and CRF groups (Z = -2.52, P = 0.012). Median BUN values were 153.46 ± 82.47 in ARF group and 169.40 ± 93.94 in CRF group. There was no significant difference in BUN value between ARF and CRF groups (P > 0.05). Median creatinine values were 2.84 ± 2.95 in ARF group and 4.78 ± 4.32 in CRF group. In serum creatinine values, a significant difference was found between ARF and CRF groups (P < 0.05).

Conclusions:

Serum NGAL levels of ARF and CRF patients were significantly higher than healthy individuals. In addition, NGAL values of patients with CRF were significantly higher than those of ARF. Serum NGAL values can be used to detect renal injury and differentiate ARF and CRF.

Losartan improved antioxidant defense, renal function and structure of postischemic hypertensive kidney

Ischemic acute renal failure (ARF) is a highly complex disorder involving renal vasoconstriction, filtration failure, tubular obstruction, tubular backleak and generation of reactive oxygen species. Due to this complexity, the aim of our study was to explore effects of Angiotensin II type 1 receptor (AT1R) blockade on kidney structure and function, as well as oxidative stress in spontaneously hypertensive rats (SHR) after renal ischemia reperfusion injury. Experiments were performed on anaesthetized adult male SHR in the model of ARF with 40 minutes clamping the left renal artery. The right kidney was removed and 40 minutes renal ischemia was performed. Experimental groups received AT1R antagonist (Losartan) or vehicle (saline) in the femoral vein 5 minutes before, during and 175 minutes after the period of ischemia. Biochemical parameters were measured and kidney specimens were collected 24h after reperfusion. ARF significantly decreased creatinine and urea clearance, increased LDL and lipid peroxidation in plasma. Treatment with losartan induced a significant increase of creatinine and urea clearance, as well as HDL. Lipid peroxidation in plasma was decreased and catalase enzyme activity in erythrocytes was increased after losartan treatment. Losartan reduced cortico-medullary necrosis and tubular dilatation in the kidney. High expression of pro-apoptotic Bax protein in the injured kidney was downregulated after losartan treatment. Our results reveal that angiotensin II (via AT1R) mediates the most postischemic injuries in hypertensive kidney through oxidative stress enhancement. Therefore, blockade of AT1R may have beneficial effects in hypertensive patients who have developed ARF.

The anti-oxidative role of micro-vesicles derived from human Wharton-Jelly mesenchymal stromal cells through NOX2/gp91(phox) suppression in alleviating renal ischemia-reperfusion injury in rats

Oxidative stress is known as one of the main contributors in renal ischemia/reperfusion injury (IRI). Here we hypothesized that Micro-vesicles (MVs) derived from human Wharton Jelly mesenchymal stromal cells (hWJMSCs) could protect kidney against IRI through mitigating oxidative stress. MVs isolated from hWJMSCs conditioned medium were injected intravenously in rats immediately after unilateral kidney ischemia for 60 min. The animals were sacrificed at 24h, 48h and 2 weeks respectively after reperfusion. Our results show that the expression of NOX2 and reactive oxygen species (ROS) in injured kidney tissues was declined and the oxidative stress was alleviated in MVs group at 24h and 48h in parallel with the reduced apoptosis and enhanced proliferation of cells. IRI-initiated fibrosis was abrogated by MVs coincident with renal function amelioration at 2 weeks. NOX2 was also found down-regulated by MVs both in human umbilical vein endothelial cells (HUVEC) and NRK-52E cell line under hypoxia injury model in vitro. In conclusion, a single administration of hWJMSC-MVs might protect the kidney by alleviation of the oxidative stress in the early stage of kidney IRI through suppressing NOX2 expression. Moreover, it could reduce the fibrosis and improved renal function.

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.

Postoperative renal function evaluation, through RIFLE criteria, of elderly patients who underwent femur fracture surgery under spinal anesthesia

INTRODUCTION

The postoperative acute renal failure (ARF) incidence in different kinds of surgery has rarely been studied. Age, cardiac dysfunction, previous renal dysfunction, intraoperative hypoperfusion, and use of nephrotoxic medications are mentioned as risk factors for ARF at the postoperative period. The postoperative ARF definition was based on the creatinine increase by the RIFLE classification (R = risk, I = injury, F = failure, L = loss, E = end stage), which corresponds to a 1.5 creatinine increase, two to three times, respectively, above the basal value. This study aimed to evaluate the postoperative ARF incidence in elderly patients who underwent femur fracture surgery under subarachnoid anesthesia and stratify it by the RIFLE criteria.

METHODS

Ninety patients older than 65 years under spinal anesthesia with fixed dosage of 15 mg of 0.5% isobaric bupivacaine associated with morphine 50 mug were studied. Immediate postoperative creatinine was considered basal and compared with maximal creatinine evaluated at 24, 48, and 72 postoperative hours.

RESULTS

The mean age of the patients was 80.27 years. ARF incidence was 24.44% and stratified this way: R = 21.11% and I = 3.33%.

CONCLUSIONS

In conclusion, the postoperative ARF incidence after femur fracture surgery in patients over 65 years was 24.44%. By analyzing the stratification based on the RIFLE classification, the incidence was categorized as Risk (R) = 21.11% and Injury (I) = 3.33%.

Curcumin protects against ischemia/reperfusion injury in rat kidneys

OBJECTIVES

Renal ischemia followed by reperfusion leads to acute renal failure in both native kidneys and renal allograft. We investigated the effect of curcumin on ischemia-reperfusion (I/R) injury and the antioxidant effects of curcumin in rats.

METHODS

Thirty rats were randomly divided into five experimental groups (control, sham, curcumin, I/R and I/R+curcumin, n=6 each). Curcumin was administered (200 mg kg(-1)) orally to curcumin and I/R+curcumin groups for 7 days. Then, the rats were subjected to bilateral renal ischemia for 45 min and followed by reperfusion for 24 h. All rats were killed and kidney function tests, serum and tissue nitric oxide (NO), protein carbonyl (PC), malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels were determined. Histopathological examinations were also performed.

RESULTS

Curcumin significantly improved the urea and cystatin C levels in I/R+curcumin group compared to I/R group (p<0.05). Reduction of serum GSH-Px was significantly improved by curcumin (p<0.001), but SOD enzyme activity did not alter (p>0.05). Treatment with curcumin also resulted in significant reduction in serum and tissue MDA, NO and PC and for tissue that were increased by renal I/R injury (p<0.001 for serum and p<0.05 for tissue, respectively). In histological examination, the rats treated with curcumin had nearly normal morphology of the kidney.

CONCLUSIONS

Based on our results, it can be concluded that curcumin protects the kidneys against I/R injury via its antioxidant effects.

Oral beta-glucan protects kidney against ischemia/reperfusion injury in rats

BACKGROUND

Ischemia-reperfusion (I/R) injury is one of the leading causes of acute renal failure. Beta-(1-->3)-glucans are glucose polymers with a variety of stimulatory effects on the immune system. We designed this study to determine the possible protective effect of the orally administered soluble beta-glucan against I/R injury.

METHODS

30 rats were randomly divided into 5 experimental groups (control, sham operated, beta-glucan, I/R and I/R+beta-glucan groups, n = 6 each). Beta-glucan was administered orally to 6 rats of the beta-glucan and I/R+beta-glucan groups. The rats were subjected to bilateral renal ischemia followed by reperfusion in the I/R and I/R+beta-glucan groups. All of the rats were then sacrificed and kidney function tests, serum and tissue oxidants and antioxidants were evaluated.

RESULTS

The serum urea and cystatin C levels were significantly higher in the I/R group compared to the I/R+beta-glucan group (p < 0.01). The serum and tissue antioxidant markers (SOD, GSH-Px) were significantly lower in the I/R group than the I/R+beta-glucan group (p < 0.01). The serum oxidant markers (NO and PC) were significantly higher in the I/R group than the I/R+beta-glucan group (p < 0.01).

CONCLUSION

Based on the present data, we conclude that increased antioxidants and decreased oxidants modulated by beta-glucan attenuated the renal I/R injury.

Stobadine protects rat kidney against ischaemia/reperfusion injury

1. Ischaemia-reperfusion (I/R) injury, one of the main causes of acute renal failure, still needs satisfactory treatment for routine clinical application. Stobadine, a novel synthetic pyridoindole anti-oxidant, has the ability to reduce tissue injury induced by mechanisms involving reactive oxygen species during I/R. The aim of the present study was to determine the effects of stobadine on renal I/R injury. 2. Forty male Wistar rats were randomly divided into four groups as follows: sham, I/R, stobadine treated and I/R + stobadine treated. Stobadine (2 mg/kg, i.v.) was given intravenously to two groups of rats. The stobadine-treated group was treated with stobadine following sham operation before the abdominal wall was closed, whereas the I/R + stobadine group received stobadine at the beginning of reperfusion. Renal I/R was achieved by occluding the renal arteries bilaterally for 40 min, followed by 6 h reperfusion. Immediately thereafter, blood was drawn and tissue samples were harvested to assess: (i) serum levels of blood urea nitrogen and creatinine; (ii) serum and/or tissue levels of malondialdehyde (MDA), glutathione (GSH), glucose 6-phosphate dehydrogenase (G-6PD), 6-phosphogluconate dehydrogenase (6-PGD), glutathione reductase (GR) and glutathione peroxidase (GPx); (iii) renal morphology; and (iv) immunohistochemical staining for P-selectin. 3. Stobadine was able to significantly attenuate the renal dysfunction as a result of renal I/R injury. Ischaemia-reperfusion resulted in a significant increase in serum and kidney MDA levels and a decrease in serum and kidney GSH. Stobadine treatment at the beginning of reperfusion attenuated both the increased MDA levels and decreased GSH secondary to I/R injury. In addition, the decreased G-6PD activity observed after I/R was significantly attenuated by stobadine treatment. Stobadine did not alter 6-PGD activity after I/R. Neither GR nor GPx activity was significantly changed in the I/R alone or the I/R + stobadine groups compared with the sham group. In addition, stobadine decreased the morphological deterioration and high P-selectin immunoreactivity secondary to renal I/R injury. 4. A pyridoindole anti-oxidant, stobadine exerts a renal protective effect in renal I/R injury, which is probably due to its radical-scavenging and anti-oxidant activities.

Emergency Department Hypotension is not an Independent Risk Factor for Post-Traumatic Acute Renal Dysfunction

BACKGROUND

Hypotension has been considered to be associated with renal dysfunction. The purpose of this study was to characterize the association of Emergency Department Hypotension (EDHypo) with post-traumatic renal insufficiency (RI) and renal failure (RF).

METHODS

A Level I center Intensive Care Unit database was analyzed. We reviewed all adult trauma patients surviving for more than 24 hours. EDHypo was defined as admission systolic blood pressure of less than 90 mm Hg, RI was defined as a peak serum creatine of > or = 2.0 mg/dL, RF was defined as requiring dialysis.

RESULTS

There were 2,574 admissions studied and RI occurred in 8.3% (213) of these patients whereas RF occurred in 1.1% (28). The mortality rate with RI was 41.0% (89) and 50.0% (14) with RF. There was no significant change in the incidence of RI, RF, or RI associated mortality during the study period. EDHypo was present in 7.9% (203) of patients and the incidence of RI was significantly higher than that of non-EDHypo patients (12.2% vs. 7.9%, p = 0.028). The incidence of RF was not different (1.0% vs. 1.1%). EDHypo was not independently associated with RI or RF but Injury Severity Score > 16, renal injury, age > 55, Body Mass Index > 30, male gender, and Intensive Care Unit (ICU) admission creatine kinase > or = 5,000 U/L had an independent association with RI. No risk factor in patients with RI could reliably predict RF.

CONCLUSIONS

EDhypo is not independently associated with post-traumatic RI or RF but severity of injury, renal injury, age, Body Mass Index, male gender, and elevated creatinine kinase are independently associated with RI. In critically ill trauma patients the incidence of RI and RF and the associated mortality rate has not changed significantly during a 6-year period despite, presumably, better understanding of resuscitative strategies.

Risk factors for death among critically ill patients with acute renal failure

CONTEXT AND OBJECTIVE

Acute renal failure is a common medical problem, with a high mortality rate. The aim of this work was to investigate the risk factors for death among critically ill patients with acute renal failure.

DESIGN AND SETTING

Retrospective cohort at the intensive care unit of Hospital Universitário Walter Cantídio, Fortaleza.

METHODS

Survivors and non-survivors were compared. Univariate and multivariate analyses were performed to establish risk factors for death.

RESULTS

Acute renal failure occurred in 128 patients (33.5%), with mean age of 49 +/- 20 years (79 males; 62%). Death occurred in 80 (62.5%). The risk factors most frequently associated with death were hypotension, sepsis, nephrotoxic drug use, respiratory insufficiency, liver failure, hypovolemia, septic shock, multiple organ dysfunction, need for vasoactive drugs, need for mechanical ventilation, oliguria, hypoalbuminemia, metabolic acidosis and anemia. There were negative correlations between death and: prothrombin time, hematocrit, hemoglobin, systolic blood pressure, diastolic blood pressure, arterial pH, arterial bicarbonate and urine volume. From multivariate analysis, the independent risk factors for death were: need for mechanical ventilation (OR = 3.15; p = 0.03), hypotension (OR = 3.48; p = 0.02), liver failure (OR = 5.37; p = 0.02), low arterial bicarbonate (OR = 0.85; p = 0.005), oliguria (OR = 3.36; p = 0.009), vasopressor use (OR = 4.83; p = 0.004) and sepsis (OR = 6.14; p = 0.003).

CONCLUSIONS

There are significant risk factors for death among patients with acute renal failure in intensive care units, which need to be identified at an early stage for early treatment.

Use of a hanging-weight system for isolated renal artery occlusion during ischemic preconditioning in mice

Renal failure from ischemia contributes to morbidity and mortality. Ischemic preconditioning (IP) represents a powerful strategy for kidney protection, and recent advances in transgenic mice may help elucidate its molecular mechanisms. However, murine IP is technically challenging and experimental details significantly influence results. Thus we developed a novel model for renal IP using a hanging-weight system for isolated renal artery occlusion. In contrast to previous models, this technique eliminates the need for clamping the vascular pedicle (artery/vein). In fact, assessment of renal injury after different time periods of ischemia (10-60 min) revealed highly reproducible increases in plasma creatinine and potassium levels, while creatinine clearance, urinary flow and potassium/sodium excretion were significantly attenuated. Using different numbers of IP cycles, we found maximal protection with four cycles of 4 min of ischemia-reperfusion. In contrast, no significant renal protection was observed with IP of the vascular pedicle. To assess transcriptional responses in this model, we isolated RNA from preconditioned kidneys and found time-dependent induction of erythropoietin mRNA and plasma levels with IP. Taken together, this model provides highly reproducible renal injury and protection by IP, thus minimizing variability associated with previous techniques based on clamping of the renal pedicle. Further studies on renal ischemia/IP in mice may consider this technique.

Effect of sevoflurane preconditioning on ischaemia/reperfusion injury in the rat kidney in vivo

BACKGROUND AND OBJECTIVE

Whereas the protective effect of anaesthetic and ischaemic preconditioning has been described for several organs, it is uncertain whether this mechanism is also effective in the kidney. We compared the effect of preconditioning with sevoflurane and preconditioning with short episodes of ischaemia on renal ischaemia/reperfusion injury in the rat in vivo.

METHODS

Fourteen days after right-sided nephrectomy, anaesthetized male Wistar rats were randomly assigned to a sham-operated group (no arterial occlusion, n = 5) or underwent 45 min of left renal artery occlusion (control group, n = 9) followed by 3 days of reperfusion. Two further experimental groups of animals were preconditioned prior to ischaemia either by administering 1 MAC sevoflurane for 15 min followed by 10 min of washout (sevoflurane group, n = 10) or by subjecting the animals to three short episodes of renal ischaemia (ischaemia-preconditioned group, n = 8). Blood creatinine was measured during reperfusion and morphological damage was assessed by histological examination.

RESULTS

Baseline creatinine values were similar in all four groups (0.7 +/- 0.2 mg dL-1; mean +/- SD) and remained unchanged in the sham-operated animals after 3 days (0.8 +/- 0.2 mg dL-1). Creatinine levels increased in the ischaemic preconditioning group (3.3 +/- 1.2 mg dL-1) and sevoflurane preconditioning group (4.0 +/- 1.1 mg dL-1) compared to the control group (1.6 +/- 0.6 mg dL-1). Morphological damage was less severe in the control group, i.e. in animals without preconditioning, than in both preconditioning groups.

CONCLUSION

Neither sevoflurane nor ischaemic preconditioning preserves renal function or attenuates cell damage in the rat in vivo.

Retrospective analysis on Chinese patients diagnosed with acute renal failure hospitalized during the last decade (1994-2003)

OBJECTIVES

To investigate the epidemiology, diagnosis and prognosis of acute renal failure (ARF) in hospitalized Chinese during the last decade.

METHODS

The diagnosis of patients with ARF in Peking University Third Hospital from January 1994 to December 2003 was reconfirmed and the data of epidemiology, etiology and prognosis were analyzed.

RESULTS

Only 209 discharged cases were diagnosed with ARF and all were reconfirmed. Two peak occurrences were found at ages of 35-45 and 60-80 with a male predominance of approximately 59.7%. Patients diagnosed with ARF accounted for 1.19 per thousand of the admissions in the same period and increased significantly in the last 5 years (p = 0.038). The creatinine level at diagnosis was 345.8 +/- 122.6 micromol/l and had no significant change (p > 0.05). The percent of hospital-acquired ARF (HA-ARF) demonstrated a significant increase in 1999-2003 compared to 1994-1998 (p = 0.008). Intrarenal ARF accounted for 73.69% and was multifactorial, with drugs, infections and operations as leading causes. Renal biopsy was performed in 37.32% (78/209) with 53.84% (42/78) having acute interstitial nephritis. Maintenance dialysis was discontinued in 46.41% because their renal function completely or partially recovered. The overall mortality was 37.91% without improvement over time. The mortality was 6.25% for patients in nephrology department, but 65.51% in ICU (p < 0.001), and was 21.6% for patients in community-acquired ARF (CA-ARF), but 63.1% in HA-ARF (p < 0.001).

CONCLUSIONS

During the past 10 years, the number of patients diagnosed with ARF has been rising in hospitalized Chinese. HA-ARF was the major source, and infections, drugs and operations were the leading causes. The diagnosis and prognosis of acute renal failure did not improve much in this population over the decade studied.

Acute renal failure and rhabdomyolysis

The clinical syndrome of rhabdomyolysis is caused by injury of skeletal muscles, leading to the release of various intracellular muscle constituents. Rhabdomyolysis occurs frequently but is usually asymptomatic (i.e., lab abnormalities only). However, in more serious cases, severe electrolyte disorders and acute renal failure may occur, leading to life-threatening situations. Rhabdomyolysis can develop in any circumstances where energy demands in muscles exceed the available energy supplies; it accounts for between 2 and 5% of all cases of acute renal failure in the ICU. Frequent causes of severe rhabdomyolysis include crush injuries, prolonged immobilization, seizures, severe infections and drug toxicity. Factors contributing to the development of more severe clinical symptoms include hypovolemia, hyperthermia, electrolyte disorders and the presence of pre-existing (congenital) muscle disorders. The diagnosis is established by elevation of serum muscle enzymes and muscle constituents such as creatinine phosphokinase and myoglobin. Preventive measures include maintenance of normal or high intravascular volume and administration of diuretics (loop diuretics rather than mannitol) once hypervolemia/euvolemia have been achieved. Some evidence suggests that early initiation of renal replacement therapy can help improve outcome. Administration of bicarbonate to induce urinary alkalosis can be considered, but it has not been proven to be effective.

Techniques for assessing and achieving fluid balance in acute renal failure

Fluid therapy, together with attention to oxygen supply, is the cornerstone of resuscitation in all critically ill patients. Hypovolemia results in inadequate blood flow to meet the metabolic requirements of the tissues and must be treated urgently to avoid the complication of progressive organ failure, including acute renal failure. The kidney plays a critical role in body fluid homeostasis. Renal dysfunction disturbs this homeostasis and requires special attention to issues of fluid balance and fluid overload. In addition, fluid therapy is the only treatment that has been shown to be effective in the prevention of acute renal failure. Special attention to volume status is therefore required in patients at risk for acute renal failure. Hypovolemia is also a major causal factor of morbidity during hemodialysis and may contribute to further renal insults. Although the importance of fluid management is generally recognized, the choice of fluid, the amount, and assessment of fluid status are controversial. As the choice of fluids becomes wider and monitoring devices become more sophisticated, the controversy increases. This article provides an overview of the concept of fluid management in the critically ill patient with acute renal failure.