The patient at risk for acute renal failure. Recognition, prevention, and preoperative optimization

Which patients are at risk for kidney dysfunction after hip fracture surgery?

BACKGROUND

Kidney dysfunction (KD) after hip fracture surgery is a major complication. However, the incidence and risk factors of KD in this population are unclear.

QUESTIONS/PURPOSES

We therefore (1) determined the incidence of KD in a large cohort of fracture patients, (2) identified preoperative risk factors predisposing to KD, and (3) determined the effect of KD on length of stay and subsequent function.

METHODS

Between April 2011 and June 2012, 450 patients (263 women) with a mean age of 73 years (range, 67-96 years) underwent surgery for hip fracture in our institution. We calculated incidence and retrospectively reviewed suspected predisposing risk factors. We report followup at 6 months.

RESULTS

The overall incidence of KD was 11% (n = 52). Forty-five patients (86%) developed acute KD and seven patients developed acute-on-chronic KD. Three of the 52 patients died during the followup time. Thirty-eight of the 52 patients (73%) regained their prior kidney function after treatment. An increased risk of KD was found in those with diabetes, shock during or after surgery, age, and preexisting KD. Mean length of stay was higher for patients with KD compared to those without: 9.6 versus 7.4, respectively. At 6 months, 39 of the 49 surviving patients (80%) were fully weightbearing.

CONCLUSIONS

Many patients at risk for postoperative KD can be identified and treated. Most patients recover from their KD and the majority return to full weightbearing.

Analysis of kidney dysfunction in orthopaedic patients

Backround

This retrospective study was undertaken to determine the incidence of kidney dysfunction (KD) and to identify potential risk factors contributing to development of KD in orthopaedic population following an elective or emergency surgery.

Methods

A total of 1025 patients were admitted in our institution over a period of one year with various indications. Eight hundred and ninety-three patients (87.1%) had a surgical procedure. There were 42 (52.5%) male and 38 (47.5%) female with a mean age of 72 years (range: 47 to 87 years). We evaluated the following potential risk factors: age, comorbidities, shock, hypotension, heart failure, medications (antibiotics, NSAIDs, opiates), rhabdomyolysis, imaging contrast agents and pre-existing KD.

Results

The overall incidence of KD was 8.9%. Sixty-eight patients developed acute renal injury (AKI) and 12 patients developed acute on chronic kidney disease (CKD). In sixty-six (82.5%) patients renal function was reversed to initial preoperative status. Perioperative dehydration (p = 0.002), history of diabetes mellitus (p = 0.003), pre-existing KD (p = 0.004), perioperative shock (p = 0.021) and administration of non-steroid anti-inflammatory drugs (NSAIDs) (p = 0.028) or nephrotoxic antibiotics (p = 0.037) were statistically significantly correlated with the development of postoperative KD and failure to gain the preoperative renal function.

Conclusion

We conclude that every patient with risk factor for postoperative KD should be under closed evaluation and monitoring.

Peri-operative renal protection: The strategies revisited

Postoperative acute renal failure (ARF) is a serious complication which can result in a prolonged hospital stay and a high mortality and morbidity. Underlying renal disease, cardiac diseases, nephrotoxin exposure and renal hypoperfusion are the possible predisposing risk factors which can create a high probability for the development of ARF. The incidence of ARF is highest after major vascular, cardiac and high-risk thoraco-abdominal surgery. Among the various renal protection strategies, adequate peri-operative volume expansion and avoidance of hypovolemia is the most accepted and practiced strategy. Numerous bio-markers of renal injury are used to estimate the presence and extent of renal insult and various new are currently under trial. Traditional pharmacological interventions like dopamine, diuretics and calcium antagonists are not currently the first line of reno-protective agents. The new non-pharmacological and pharmacological methods may improve outcome in renal transplantation, contrast-induced nephropathy and in various other settings of ARF. The current review is an attempt to refresh the knowledge and put forth the various renal protection strategies during the peri-operative period.

Rhabdomyolysis following renal autotransplantation

A 26-year-old male body builder diagnosed with renal artery stenosis and middle aortic syndrome underwent an autotransplantation with bench reconstruction and end-to-end anastomosis using the hypogastric artery. Shortly after the procedure, the patient developed rhabdomyolysis and renal insufficiency, possibly related to his increased muscle mass, potentially greater susceptibility to hypertrophic skeletal muscle cells or his unique vascular condition. We review the risk factors, diagnosis, management and outcome of a case of rhabdomyolysis in a male patient who underwent autotransplantation for renal vascular hypertension.

[Risk factors for renal dysfunction after total hip arthroplasty]

INTRODUCTION

Postoperative renal dysfunction (PRD) is well-documented after cardiovascular surgery but there are only limited available data concerning major orthopedic surgery, although patients may have several risk factors prone to impair renal function. We designed an epidemiologic prospective study to assess the incidence of PRD after total hip arthroplasty (THA) and to determine risk factors.

PATIENTS AND METHODS

Were included in the study 755 patients scheduled for THA in a single centre, over a 14 months period. Thirty-one demographic, clinical and biological parameters were collected for each patient. PRD was defined by a value of glomerular filtration, determined by the Cockroft and Gault formula<or=60 ml/min per 1.73 m2, on the seventh postoperative day. Risk factors were determined by univariate and then multivariate analyses using a linear regression model.

RESULTS

Pre- and postoperatively (POD7), respectively 22.4% and 31.4% of the patients, had a creatinine clearance less than 60 ml/min per 1.73 m2. Univariate analysis documented age, ASA score, diabetes mellitus, chronic hypertension, the use of diuretics and NSAID, anemia, and an increased value of plasma urea as risk factors. Risk factors documented by multivariate analysis were: preoperative creatinine clearance less than 60 ml/min per 1.73 m2, (OR: 5.8, 95% confidence interval: [1.6-8.1], p=0.0006), preoperative plasma urea greater than 7.49 mmol/l (2.1 [1.4-11.1], p=0.04), age above 70 years (1.8 [1.1-4.3], p=0.02), and duration of NSAID's treatment beyond 5 days (3.2 [1.4-7.1], p=0.02).

CONCLUSION

PRD is common after THA and is prone to develop in aged patients with comorbidities. Duration of NSAID's administration should be limited in those patients.

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%.

Renal function and histology after acute hemorrhage in rats under dexmedetomidine action

PURPOSE: About 50 % of indications for dialysis in acute renal failure are related to problems originated during the perioperative period. Intraoperative hemodynamic changes lead to renal vasoconstriction and hypoperfusion. Previous studies have not defined the dexmedetomidine renal role in hemorrhage situations. This study evaluated the effect of dexmedetomidine on renal function and histology after acute hemorrhage in rats. METHODS: Covered study with 20 Wistars rats, anesthetized with sodium pentobarbital, 50 mg. kg-1, intraperitoneal, randomized into 2 groups submitted to 30% volemia bleeding: DG - iv dexmedetomidine, 3 µg. kg-1 (10 min) and continuous infusion - 3 µg. kg-1. h-1; CG - pentobarbital. For renal clearance estimative, sodium p-aminohippurate and iothalamate were administered. Studied attributes: heart rate, mean arterial pressure, rectal temperature, hematocrit, iothalamate and p-aminohippurate clearance, filtration fraction, renal blood flow, renal vascular resistance, and histological evaluations of the kidneys. RESULTS: DG showed smaller values of heart rate, mean arterial pressure, and renal vascular resistance, but iothalamate clearance and filtration fraction values were higher. There was similarity in p-aminohippurate clearance and renal blood flow. Both groups had histological changes ischemia-like, but dexmedetomidine determined higher tubular dilatation scores. CONCLUSION: In rats, after acute hemorrhage, dexmedetomidine determined better renal function, but higher tubular dilation scores.

Valve Replacement Surgery Complicated by Acute Renal Failure-Predictors of Early Mortality

BACKGROUND

Acute renal failure (ARF) is a serious complication of valve replacement surgery. The aim of this study was to determine the predictors of early mortality and if causative factors are preventable.

METHODS

In the 25-year period between 1977 and 2002, 255 (2.6%) of 9721 patients (11,007 operations), who had valve replacement surgery, were managed for ARF with dialysis. The mean age of the patient population was 67.1 +/- 11.6 years (range 24 to 87 years, median 70.3 years). Fifty preoperative, operative, and postoperative risk factors were assessed as predictors of early mortality by univariate and multivariate modeling.

RESULTS

The early mortality was 25.1% (64 patients). The predictors by univariate analysis were: New York Heart Association class (p = 0.001); ASA within 5 days (p = 0.030); cardiogenic shock (p = 0.010); infection--perioperative sepsis and preoperative endocarditis (p = 0.000); intraoperative stroke (p = 0.003); status--emergent (p = 0.000); mitral valve replacement (p = 0.040); ischemic (X-clamp) time >120 minutes (p = 0.020); cardiopulmonary bypass time >180 minutes (p = 0.000); surgical time >360 minutes (p = 0.000); surgical hemorrhage (p = 0.020); acute respiratory distress syndrome (ARDS) (p = 0.040). Multivariate predictors were urgent status of operation, odds ratio (OR) 0.3 (p = 0.029); emergent status of operation, OR 5.8 (p = 0.034); ischemic (X-clamp) time >120 minutes, OR 4.4 (p = 0.030); surgical time >360 minutes, OR 6.3 (p = 0.019); surgical hemorrhage, OR 5.1 (p = 0.003); perioperative nosocomial sepsis, OR 3.8 (p = 0.006); and preoperative endocarditis, OR 4.4 (p = 0.004).

CONCLUSIONS

Early mortality from ARF in valve replacement surgery is related to emergent status, ischemic and surgical times, surgical hemorrhage, and nosocomial infection/preoperative endocarditis. Among the variables assessed, preoperative renal insufficiency, unstable angina/recent myocardial infarction <6 weeks, and concomitant coronary artery bypass were not predictive. The evaluation of predictors of ARF requires further extensive assessment.

Renal protection strategies in the perioperative period

The development of acute renal failure (ARF) in the perioperative period continues to be a vexing condition associated with high morbidity and mortality rates which have been unchanged for several decades. In this article I briefly review recent research categorizing pathogenesis of ARF and mechanisms of recovery. Once ARF is established, its maintenance phase is dependent on several mechanisms that interact with cellular integrity. The main focus of the article is on assessing clinical and experimental interventions to prevent ARF. Unfortunately, existing pharmacological and other interventions show a rather limited efficacy in preventing ARF.

Assessment of acute renal failure patients treated in our nephrology clinic between 1996 and 2002

Acute renal failure (ARF) is a cause of high morbidity and mortality associated with long hospital stay, and expensive treatment. The initial approach to patients with ARF should be focused on preventing future injury to the kidney. Two hundred eighty-three ARF patients, treated from January 1996 to June 2002, were retrospectively investigated for their etiology, clinic features, and laboratory characteristics, as well as treatment results and mortality rate. The mean age was 52.3 +/- 18.7 years. Patients with hospital-acquired ARF comprised 38.8% of the sample. Renal causes (60%) were responsible for most ARF patients. They were medical (63.95%), surgical (23.67%), and obstetric (12.4%) causes. Twenty-five percent of patients with ARF had multiple etiologies. Hemolysis elevated liver enzymes low platelets (HELLP) syndrome was seen in the most of the obstetric-related ARF cases. Signs of hypervolemia were present in approximately 50% of the cases. Oliguric patients comprised 59.7% of the sample, and the mean time to oliguria was 5.2 +/- 4.1 days. The necessity of dialysis was greater in oliguric patients (42.6%) and the ratio of complete/partial improvement (82.2%) was greater among non-oligoanuric patients. However, there was no significant difference between mortality rates. Irreversible renal insufficiency did not develop in the non-oliguric cases. Also, 7.4% of ARF patients died, with the main causes being infection (31.8%) and cardiovascular events (27.2%). Medical problems are important in the etiology of ARF as well as obstetric cases. The mortality rate was low in our cases, a situation that may be explained by medical causes being of importance in the etiology. We are of the opinion that early referral of patients to a nephrologist and following treatment in the nephrology clinic may positively affect the outcome.

Preoperative and perioperative predictors of the need for renal replacement therapy after orthotopic liver transplantation

BACKGROUND

Acute renal failure developing after orthotopic liver transplantation (OLTx) requiring renal replacement heralds a poor prognosis. Our center has previously reported a 1-year survival of only 41.8%. We undertook this study to determine whether we could identify preoperative and perioperative factors that would predict which patients are at risk.

METHODS

OLTxs performed between January 1, 1996, and December 31, 2001, were included in our retrospective database review. Combined kidney-liver transplants or patients with preoperative renal replacement therapy (RRT) were excluded. A total of 724 OLTxs were studied, which were divided into group I: no RRT, n=637; group II: hemodialysis only post-OLTx, n=17; and group III: continuous RRT post-OLTx, n=70. Univariate and stepwise logistic multivariate analyses were performed.

RESULTS

Preoperative serum creatinine greater than 1.9 mg/dL (odds ratio [OR] 3.57), preoperative blood urea nitrogen greater than 27 mg/dL (OR 2.68), intensive care unit stay more than 3 days (OR 10.23), and Model for End-Stage Liver Disease score greater than 21 (OR 2.5) were significant. A clinical prediction model was constructed: probability of requiring dialysis posttransplant=(-2.4586+1.2726 [creatinine >1.9] + 0.9858 [blood urea nitrogen >27] + 0.4574 [Model for End-Stage Liver Disease score >21] + 1.1625 [intensive care unit days >3]). A clinical prediction rule for patients with a score greater than 0.12 was applied to OLTx recipients who underwent transplantation in 2002. A total of 15 of 20 patients who received RRT and 111 of 121 who did not were correctly classified with the model.

CONCLUSIONS

This model allowed us to identify patients at high risk for developing the need for RRT postoperatively. Strategies for these patients to prevent or ameliorate acute renal failure and reduce the need for RRT postoperatively are needed.

Perioperative management and monitoring in anaesthesia

In recent years, several risk factors for adverse outcome in patients undergoing anaesthesia have been identified. Besides human errors, cardiovascular and respiratory complications are associated with substantial morbidity. Assessment of complications has promoted the introduction of basic physiological monitoring in clinical practice. Whether monitoring directly affects outcome is not proven; however, circumstantial evidence suggests that basic cardiorespiratory monitoring decreases the incidence of serious accidents. Prevention of hypothermia also reduces anaesthesia-related morbidity. Measurement of body temperature is mandatory, and active warming is a simple, effective technique to avoid hypothermia. Evidence is growing that patients with known or suspected coronary artery disease should be treated with beta blockers perioperatively. Whether the type of anaesthesia-ie, general or regional-is relevant to perioperative mortality remains unclear. In subgroups of patients at high risk, neuraxial anaesthesia reduces the rate of respiratory and cardiovascular complications.

Effect of fenoldopam on renal function after nephrotomy in normal dogs

OBJECTIVE

To evaluate effects of fenoldopam on renal function in normal dogs subjected to bisection nephrotomy. In addition, effects of bisection nephrotomy on renal function in normal dogs were evaluated.

STUDY DESIGN

Controlled, randomized, blinded experiment.

SAMPLE POPULATION

Sixteen mixed-breed adult dogs.

METHODS

Dogs were paired for sex, body weight, and approximate age and assigned to 1 of 2 groups: fenoldopam (F) or placebo (P). Baseline glomerular filtration rate (GFR) based on quantitative renal scintigraphy using (99m)Tc-DTPA, blood urea nitrogen (BUN), serum creatinine (SCr), urinalysis, and urine culture were performed before surgery. Left nephrotomy was performed via median celiotomy. Group F dogs were administered intravenous (IV) fenoldopam (0.1 microg/kg/min) for 90 minutes, whereas group P dogs were administered an equivalent volume of saline (0.9 % NaCl) solution for 90 minutes. Temperature, heart rate, respiration, direct arterial blood pressure, and urine volume were recorded during anesthesia. Renal function was assessed by measuring SCr, BUN, and GFR at 1, 21, and 42 days after surgery.

RESULTS

There was no significant difference between groups in measured physiologic variables. No significant difference in GFR, BUN, or SCr between groups or between operated or control kidneys was detected.

CONCLUSIONS

Bisection nephrotomy in normal dogs with renal arterial occlusion of 15 minutes and using a simple continuous capsular closure does not adversely affect renal function.

CLINICAL RELEVANCE

Bisection nephrotomy, as described in this study, does not decrease renal function; perioperative administration of renoprotective agents is not necessary in normal dogs.