Renal failure after operation for abdominal aortic aneurysm

Relationship between intraoperative dopamine infusion and postoperative acute kidney injury in patients undergoing open abdominal aorta aneurysm repair

Background

Acute kidney injury (AKI) is one of the most common complications in patients undergoing open abdominal aortic aneurysm (AAA) repair. Dopamine has been frequently used in these patients to prevent AKI. We aimed to clarify the relationship between intraoperative dopamine infusion and postoperative AKI in patients undergoing open AAA repair.

Methods

We analyzed 294 patients who underwent open AAA repair at a single tertiary center from 2009 to 2018, retrospectively. The primary outcome was the incidence of postoperative AKI, determined by the Kidney Disease Improving Global Outcomes definition, after open AAA repair. Secondary outcomes included survival outcome, hospital and intensive care unit length of stay, and postoperative renal replacement therapy (RRT).

Results

Postoperative AKI occurred in 21.8% (64 out of 294 patients) The risk of postoperative AKI by intraoperative dopamine infusion was greater after adjusting for risk factors (odds ratio [OR] 2.56; 95% confidence interval [CI], 1.09–5.89; P = 0.028) and after propensity score matching (OR 3.22; 95% CI 1.12–9.24; P = 0.030). On the contrary, intraoperative norepinephrine use was not associated with postoperative AKI (use vs. no use; 19.3 vs. 22.4%; P = 0.615). Patients who used dopamine showed higher requirement for postoperative RRT (6.8 vs. 1.2%; P = 0.045) and longer hospital length of stay (18 vs. 16 days, P = 0.024).

Conclusions

Intraoperative dopamine infusion was associated with more frequent postoperative AKI, postoperative RRT, and longer hospital length of stay in patients undergoing AAA repair, when compared to norepinephrine. Further prospective randomized clinical trial may be necessary for this topic.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-022-01624-6.

Renal function after abdominal aortic aneurysm repair in patients with baseline chronic renal insufficiency: open vs. endovascular repair

BACKGROUND

The aim of this study is to analyze renal function impairment (RFI) after abdominal aortic aneurysm (AAA) repair in patients with preoperative chronic kidney disease (CKD).

METHODS

Retrospective cohort study of patients with CKD undergoing elective AAA repair between 2008-2015, dividing the sample into two groups: open repair (OR) and endovascular repair (EVAR). The primary outcome was RFI defined by the RIFLE scale, studying Risk (1.5-fold increase in Cr or GFR decline >25% compared to baseline) and kidney injury (doubling of Cr or GFR decline >50%).

RESULTS

Seventy-five patients (OR=29, EVAR=46). Baseline characteristics for OR and EVAR were similar except for age (70.4 vs. 77.2 years; P<0.001), coronary artery disease (31% vs. 56.5%; P=0.04), neck length (12.3 vs. 22.7 mm; P=0.001) and baseline GFR (40.6 vs. 36.9 mL/min; P=0.03). There were no inter-group differences in postoperative RFI: Risk of RFI 13.8% OR vs. 13% EVAR and kidney Injury 6.9% vs. 0% (P=0.19). There were also no differences in RFI at one year. Comparing GFR and Cr after surgery and at 12 months to baseline values, the OR group presented a significant postoperative decline in GFR compared to EVAR group (-3.8% vs. 11.1%; P=0.03), which had recovered at one-year follow-up (16.6% vs. 9.5%; P=0.43), while EVAR group presented with a tendency toward increased Cr during follow-up (-9.2% vs. 2.2%; P=0.08). Multivariate analysis did not identify independent RFI prognostic factors.

CONCLUSIONS

Both techniques can be used safely in patients with CKD and baseline CKD is not a limiting factor for either technique. RFI is rare and transient in both groups.

Predictors of renal dysfunction after endovascular and open repair of abdominal aortic aneurysms

OBJECTIVE

Renal complications after repair of abdominal aortic aneurysms (AAAs) have been associated with increased morbidity and mortality. However, limited data have assessed risk factors for renal complications in the endovascular era. This study aimed to identify predictors of renal complications after endovascular AAA repair (EVAR) and open repair.

METHODS

Patients who underwent EVAR or open repair of a nonruptured infrarenal AAA between 2011 and 2013 were identified in the National Surgical Quality Improvement Project Targeted Vascular module. Patients on hemodialysis preoperatively were excluded. Renal complications were defined as new postoperative dialysis or creatinine increase >2 mg/dL. Patient demographics, comorbidities, glomerular filtration rate (GFR), operative details, and outcomes were compared using univariate analysis between those with and without renal complications. Multivariable logistic regression was used to identify independent predictors of renal complications.

RESULTS

We identified 4503 patients who underwent elective repair of an infrarenal AAA (EVAR: 3869, open repair: 634). Renal complication occurred in 1% of patients after EVAR and in 5% of patients after open repair. There were no differences in comorbidities between patients with and without renal complications. A preoperative GFR <60 mL/min/1.73m2 occurred more frequently among patients with renal complications (EVAR: 81% vs 37%, P < .01; open: 60% vs 34%, P < .01). The 30-day mortality was also significantly increased (EVAR: 55% vs 1%, P < .01; open: 30% vs 4%, P < .01). After adjustment, renal complications were strongly associated with 30-day mortality (odds ratio [OR], 38.3; 95% confidence interval [CI], 20.4-71.9). Independent predictors of renal complications included GFR <60 mL/min/1.73m2 (OR, 4.6; 95% CI, 2.4-8.7), open repair (OR, 2.6; 95% CI, 1.3-5.3), transfusion (OR, 6.1; 95% CI, 3.0-12.6), and prolonged operative time (OR, 3.0; 95% CI, 1.6-5.6).

CONCLUSIONS

Predictors of renal complications include elevated baseline GFR, open approach, transfusion, and prolonged operative time. Given the dramatic increase in mortality associated with renal complications, care should be taken to use renal protective strategies, achieve meticulous hemostasis to limit transfusions, and to use an endovascular approach when technically feasible.

Does diabetic status in the ICU predict haemofiltration requirement? The haemofiltration in the ICU and diabetic status (HIDS) study

Diabetes is already a major health burden and prevalence is expected to double by 2025. The impact of diabetes and clinical outcomes in the intensive care unit is an evolving area of research. This study seeks to identify whether diabetic status is an independent risk factor for haemofiltration. This is a retrospective cohort study. All unique patients from a seven-year period from 2004 to 2010 at a major intensive care unit in Melbourne, Australia were analysed using multivariate regression to look for an association between diabetic status and haemofiltration. After exclusion criteria there were 7262 patients, 1674 with a history of diabetes (median age of 69, 66.72% male) and 5588 without a history of diabetes (median age 64, 64.13% male). Diabetic status was an independent risk factor (odds ratio 1.401, 95% confidence interval 1.079 to 1.820, P=0.011) for haemofiltration. Further research may identify intensive care unit-based renoprotective measures specifically for patients with diabetes.

Urinary cystatin C as an early biomarker of acute kidney injury after open and endovascular abdominal aortic aneurysm repair

BACKGROUND

Acute kidney injury (AKI) after open repair (OR) and endovascular repair (EVAR) of abdominal aortic aneurysm (AAA) is associated with increased mortality and hospital costs. Early detection of AKI is critical to prevent its progression. Recent findings demonstrate that elevated levels of urinary cystatin C (uCysC) may reflect tubular dysfunction. We prospectively evaluated whether uCysC can detect renal dysfunction earlier than serum creatinine (sCr).

METHODS

In a prospective study, 126 consecutive patients (mean age ± SD, 69.1 ± 8.66 years) with AAA (EVAR = 87, OR = 39) were enrolled. sCr and uCysC were measured preoperatively (baseline) and at 6, 24, and 48 hr postoperatively. A final measurement was made on day 5. AKI was defined according to Acute Kidney Injury Network criteria.

RESULTS

The incidence of AKI was significantly higher (χ(2) test, P < 0.05) in the OR group (n = 13, 33%) than in the EVAR group (n = 15, 17%). The baseline median (interquartile range) value of uCysC was significantly higher (t-test, P < 0.05) in patients of both groups (OR-EVAR) who developed AKI from those who did not (OR/AKI group: 0.06 [0.02-0.12] mg/L, EVAR/AKI group: 0.08 [0.05-0.11] mg/L versus no-AKI subjects: 0.04 [0.02-0.07] mg/L). Subsequent analysis showed that at 6 hr postoperatively, the patients who developed AKI increased their uCysC levels significantly from baseline (OR/AKI group: 0.58 [0.42-0.70] mg/L, EVAR/AKI group: 0.59 [0.30-1.07] mg/L). The median value of uCysC in AKI patients increased at 24 hr (OR/AKI group: 1.37 [0.78-3.40] mg/L, EVAR/AKI group: 2.11 [0.70-2.42] mg/L) and peaked at 48 hr (OR/AKI group: 6.16 [1.74-10.73] mg/L, EVAR/AKI group: 2.57 [1.21-7.40] mg/L), while no increase was observed among those who did not develop AKI at the same time points (0.06 [0.04-0.14] vs. 0.08 [0.04-0.19] mg/L). The diagnostic accuracy of uCysC at 6 hr post-surgery was excellent (area under the curve - receiver-operating characteristic [AUC-ROC] = 0.968), significantly higher than sCr (AUC-ROC = 0.844) and a cutoff value set at 0.30 mg/L can diagnose AKI with a sensitivity of 85.71% and a specificity of 98.97%.

CONCLUSIONS

uCysC is superior to sCr in the early diagnosis of AKI following open and endovascular AAA repair.

Clinical Results of Endovascular Abdominal Aortic Aneurysm Repair in Patients with Renal Insufficiency without Hemodialysis

OBJECTIVE

Chronic renal insufficiency may be a relative contraindication to endovascular aneurysm repair (EVAR) for the use of contrast enhanced mediums. It is thought that more contrast enhanced media are needed in patients who are not anatomically suitable for EVAR, because of procedural difficulties. We reviewed a 2 year EVAR experience at our institution to determine whether the procedure and use of contrast enhanced mediums has any deleterious effect on renal function in patients with pre-existing chronic renal insufficiency.

MATERIALS AND METHODS

EVAR was performed in 46 patients with pre-existing chronic renal insufficiency without hemodialysis. Patients were retrospectively assigned to two groups on the basis of their preoperative creatinine clearance levels. Furthermore, patients were assigned to two other groups on the basis of anatomical suitability for EVAR. The absolute change in the serum creatinine (Cr) level was reviewed in the each renal insufficiency group between the preoperative and post-operative time periods.

RESULTS

No increase in the serum Cr level was noted, and no patient required temporary or permanent hemodialysis, in any of the groups.

CONCLUSIONS

EVAR with contrast agents can be accomplished in patients with chronic renal insufficiency without hemodialysis; therefore,elevated Cr levels maynot be a contraindication in EVAR.

The prevention of acute kidney injury an in-depth narrative review: Part 2: Drugs in the prevention of acute kidney injury

The second part of this in-depth clinical review focuses on drugs used in the prevention of AKI in the patient at risk and/or in the management of the patient with incipient AKI. Among the drugs used to maintain a normal renal perfusion pressure, norepinephrine and vasopressin are most commonly used in hypotensive critically ill patients. The most recent RCT did not find a difference between low-dose vasopressin plus norepinephrine and norepinephrine alone in patients with septic shock, suggesting that either approach is reasonable. However, vasopressin may be beneficial in the less severe septic shock subgroup. Loop diuretics may convert an oliguric into a non-oliguric form of AKI that may allow easier fluid and/or nutritional support of the patient. Volume overload in AKI patients is common and diuretics may provide symptomatic benefit in that situation. However, loop diuretics are neither associated with improved survival, nor with better recovery of renal function in AKI. Among the renal vasodilating drugs, the routine administration of dopamine to patients for the prevention of AKI or incipient AKI is no longer justified. On the other hand, although additional studies may be warranted, fenoldopam may appear to be a likely candidate for the prevention of AKI, particularly in critically ill patients, if the positive results obtained in some recent studies are confirmed. Trials with natriuretic peptides were in general inconclusive but despite the fact that nesiritide is currently approved by the FDA only for the treatment of heart failure, this vasodilator may in the future play a role in the prevention of AKI, particularly in association with heart failure and cardiac surgery. The most recent trials seem to confirm a potential positive preventive effect of N-acetylcysteine (NAC), particularly in contrast-induced nephropathy (CIN), NAC alone should never take the place of IV hydration in patients at risk for CIN; fluids likely have a more substantiated benefit. At present, initiation of statin therapy for the prevention of CIN cannot be recommended, but these drugs should not be stopped before a radiological intervention in patients on chronic statin therapy. Rasburicase is very effective in the prevention of acute tumour lysis syndrome. Erythropoietin (EPO) has tissue-protective effects and prevents tissue damage during ischaemia and inflammation, and currently trials are performed with EPO in the prevention of AKI post-cardiac surgery, CIN and post-kidney transplantation. From this review it becomes clear that single-drug therapy will probably never be effective in the prevention of AKI and that multiple agents may be needed to improve outcomes. In addition, drugs should be administered early during the course of the disease.

Acute renal failure after endovascular vs open repair of abdominal aortic aneurysm

OBJECTIVE

Endovascular aneurysm repair (EVAR) is an increasingly used alternative to open surgical repair of unruptured abdominal aortic aneurysms (AAAs). The effect of EVAR on postprocedure acute renal failure has not been determined. We hypothesized that EVAR would be associated with a lower risk of acute renal failure and acute renal failure requiring hemodialysis.

METHODS

A retrospective cohort study was conducted of the 2002 Nationwide Inpatient Sample, the largest all-payer inpatient care database in the United States, reflecting discharges from a representative sample of United States hospitals. We identified 6614 discharges with a primary diagnosis of unruptured AAA and a primary procedure code for open AAA repair or EVAR. We excluded 56 patients with end-stage renal disease and 42 patients who underwent concomitant aortorenal bypass. We compared EVAR vs open repair in this cohort. The main outcome measures were acute renal failure and acute renal failure requiring dialysis.

RESULTS

A total of 6516 patient discharges met the inclusion criteria for the study, and postprocedure acute renal failure developed in 439 (6.7%). EVAR was associated with lower odds of acute renal failure (adjusted odds ratio, 0.42; 95% confidence interval, 0.33 to 0.53) and acute renal failure requiring dialysis (adjusted odds ratio, 0.30, 95% confidence interval, 0.15 to 0.63). Results were similar when EVAR and open AAA repair were compared within quintiles of the propensity score for the receipt of EVAR.

CONCLUSIONS

Compared with open AAA repair, EVAR is associated with a lower risk of postprocedure acute renal failure.

The Management of Abdominal Aortic Aneurysms in Patients with Concurrent Renal Impairment

INTRODUCTION

Patients with concurrent renal impairment and abdominal aortic aneurysms present a significant challenge in terms of pre-operative, intra-operative and post-operative management. This aim of this review was to determine the risks of surgery in this patient group and determine whether any clear management strategies exist to enhance their clinical management.

METHODS

Systematic review of published literature giving details of the outcome of open or endovascular abdominal aortic aneurysm repair in patients with pre-operative renal impairment. Papers concerning the management of post-operative acute renal failure in patients with normal pre-operative renal function has not been included.

RESULTS

There is little data regarding patients with end-stage renal failure and AAA although these patients appear to have a high peri-operative mortality rate. In contrast, those with renal impairment do not have a significantly higher mortality rate than those with normal renal function, rather they have a higher risk of complications associated with surgery and may require more intensive post-operative organ system support than normal patients. Many have a transient deterioration in renal function in the immediate peri-operative period that will resolve. In the case of patients with ruptured AAA, it is not clear whether pre-operative renal impairment affects mortality.

Synthetic Human α-Atrial Natriuretic Peptide Improves the Management of Postoperative Hypertension and Renal Dysfunction after the Repair of Abdominal Aortic Aneurysm

OBJECTIVE

Delayed hypertension (HT) and renal dysfunction (RD) are observed after aortic operations accompanied by infra-renal aortic cross-clamping (AXC). Atrial natriuretic peptide (ANP) has effects on vasodilation and renal protection, and we examined the hypothesis that synthetic human alpha-ANP (hANP) improves the postoperative management for abdominal aortic aneurysm (AAA).

METHODS

Fifty patients undergoing elective aneurysmectomy for infrarenal-AAA between 1998 and 2001 (M:F = 43:7, mean age 70.5 +/- 7.7 years) were randomly allocated to one of 2 groups; Group H (n = 24) received hANP immediately after operation (initial dose: 0.025 microg/kg/min), and Group C (n = 26) served as a control group.

RESULTS

All patients in Group C required nicardipine hydrochloride (4.41 +/- 1.68 mg/h) for prevention of postoperative HT, whereas only 6 patients in Group H required the increase in hANP dose due to HT (P < 0.0001). Maximum hANP dose was 0.035 +/- 0.019 microg/kg/min. Group H showed significantly smaller furosemide dosage in the initial 3 days (H vs. C; 9.2 +/- 11.0 vs. 58.8 +/- 41.5 mg, P < 0.0001), significantly lower peak-Crn (H vs. C; 1.16 +/- 0.53 vs. 2.58 +/- 1.42 mg/dL, P < 0.0001), and significantly lower plasma renin-activity (7.09 +/- 2.38 vs. 11.52 +/- 4.89 ng/mL/h, P = 0.0002) and aldosterone (51.6 +/- 12.7 vs. 81.2 +/- 34.2 pg/mL, P = 0.0002) on the first postoperative day than Group C did.

CONCLUSIONS

These results imply that renin-angiotensin system may play a role in the incidence of postoperative HT and RD, and suggest that hANP infusion is a simple, reliable, and effective method for management during the immediate period after AAA operations.

Incidence and circumstances of serum creatinine increase after abdominal aortic surgery

OBJECTIVE

To evaluate the incidence and the circumstances of a moderate increase in serum creatinine early after elective abdominal aortic surgery.

DESIGN

Prospective clinical observational study.

SETTING

Surgical intensive care unit in a university hospital.

PATIENTS

Two hundred and fifteen consecutive adult patients operated on for infra-renal abdominal aortic surgery during 1 year.

INTERVENTIONS

A moderate increase in plasma creatinine of 20% from preoperative value (renal dysfunction, RD) was systematically recorded during the first 3 days following surgery. Organ dysfunctions (cardiac, pulmonary, haematological, and neurological) were assessed.

MEASUREMENTS AND RESULTS

Forty-three patients (20%) experienced a postoperative RD; six of these required dialysis. RD was associated with other organ dysfunctions in 60.5% patients. Mortality rate was significantly higher for patients who had a RD, than patients without RD (9.3% vs 1.2%, P<0.02). Mean ICU stay of patients with RD was significantly longer (7.9+/-5.6 days vs 5.0+/-1.8 days, P<0.01). However, patients with RD but without other organ dysfunctions had a mortality rate of 0% and did not have a significantly longer stay in ICU than patients without any organ dysfunctions (5.2+/-2.1 days vs 4.6+/-1.2 days, P=0.09).

CONCLUSION

Our results suggest that a postoperative 20%-increase in plasma creatinine after abdominal aortic surgery is not rare and occurs frequently with other organ dysfunction.

Long-term renal function following endovascular aneurysm repair with infrarenal and suprarenal aortic stent-grafts

PURPOSE

To determine in a retrospective analysis the incidence of renal impairment (RI) following endovascular repair (EVR) of abdominal aortic aneurysm (AAA), to assess the morbidity and mortality in endograft patients with preoperative RI, and to examine the impact of suprarenal stent-grafts on renal function.

METHODS

From March 1994 to October 2001, 315 AAA patients (289 men; mean age 72.4+/-7.0 years) undergoing EVR were entered prospectively into a vascular registry. The patients received either an in-house custom-made stent-graft or one of several commercially made devices implanted with infrarenal or suprarenal fixation. Renal function was monitored by serum creatinine measurements prior to discharge and at 3, 6, and 12 months and annually thereafter. Preoperative RI was defined as a serum creatinine >130 micro mol/L and/or long-term dialysis. Postoperative RI referred to a >20% increase in the serum creatinine over baseline. Additional deterioration of renal function in patients with preoperative RI was referred to as postoperatively worsened RI.

RESULTS

Of the 315 patients treated, 220 (69.8%) were considered high risk (ruptured AAA or ASA grade III or IV). Sixty-nine (21.9%) patients had preoperative RI (6 [1.9%] on preoperative dialysis). A suprarenal stent-graft was used in 169 (53.7%) patients and infrarenal stent-graft in the remaining 146 (46.3%). The mean follow-up was 30.1+/-22.7 months. Postoperative RI occurred in 53 (16.8%) patients (24 [7.6%] transient, 29 [9.2%] persistent). Patients with preoperative RI had a significantly higher incidence of postoperatively worsened RI (37.7% versus 11.0%, p<0.0001) and a higher mortality related to RI (7.2% versus 1.6%, p=0.02). Suprarenal fixation had no influence on the incidence of RI, on perioperative mortality, or on mortality related to RI. The only significant predictive factor of postoperative RI was preoperative RI (risk ratio 5.09, 95% CI 2.38 to 10.87, p=0.0001).

CONCLUSIONS

Endovascular AAA repair may lead to persistent postoperative RI in nearly 10% of cases, especially in patients with preoperative RI. Suprarenal stent-graft fixation does not seem to have any deleterious effect on renal function. Further long-term studies are required to confirm the innocuous nature of transrenal stent placement.

Ruptured aneurysm of the infrarenal abdominal aorta: impact of age and postoperative complications on mortality

Between 1985 and 2000, a total of 871 patients underwent surgical treatment for infrarenal abdominal aortic aneurysm (AAA), including 98 (11.2%) presenting with ruptured abdominal aortic aneurysms (RAAA). An optimized operative protocol was used to treat 77 RAAA starting in January 1989. The main features of the optimized protocol are routine use of intraoperative autotransfusion, revascularization by aortoaortic bypass, absence of systemic heparinization, and use of a collagen-impregnated prosthesis. Intraoperative mortality (IOM) was 3.8%. Postoperative mortality at 1 month (POM1) was 25.9% and postoperative mortality at 3 months (POM3) was 33.7%. Heart failure (p <0.001), hemodynamic shock (p <0.001), and hemorrhage (p = 0.04) were the only complications correlated with POM1. Pneumonia (p = 0.01) and sepsis (p = 0.01) were the only complications correlated with POM3. Isolated acute renal insufficiency was not a significant risk factor for postoperative mortality. Using a cutoff of 75 years, there was a significant age-related difference (p = 0.025) for POM1 but not for IOM and POM3. The findings of this study show that optimizing the operative protocol decreases mortality related to RAAA. The main predictor of POM1 was hemodynamic status while the main predictor of POM3 was infection. Isolated acute renal insufficiency was not a risk factor for mortality. Age should not be considered a contraindication for operative treatment.

Acute renal failure in the surgical setting

Acute renal failure (ARF) is an unwelcome complication of major surgical procedures that contributes to surgical morbidity and mortality. Acute renal failure associated with surgery may account for 18-47% of all cases of hospital-acquired ARF. The overall incidence of ARF in surgical patients has been estimated at 1.2%, although is higher in at-risk groups. Mortality of patients with ARF remains disturbingly high, ranging from 25% to 90%, despite advances in dialysis and intensive care support. Appreciation of at-risk surgical populations coupled with intensive perioperative care has the capacity to reduce the incidence of ARF and by implication mortality. Developments in understanding the pathophysiology of ARF may eventually result in newer therapeutic strategies to either prevent or accelerate recovery from ARF. At present the best form of treatment is prevention. In this review the epidemiology, pathophysiology, diagnosis, treatment and possible prevention of ARF will be discussed.

Pravastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, attenuates renal injury in an experimental model of ischemia-reperfusion

BACKGROUND

Renal dysfunction due to ischemia-reperfusion (IR) injury is a common problem following renovascular surgery or kidney transplantation. There is a lot of emerging evidence that statins, 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors, have anti-inflammatory properties and exert direct beneficial effects on the vascular endothelium. The aim of this study was to determine if pretreatment with pravastatin would attenuate the acute renal dysfunction that occurs following IR injury in an experimental model.

MATERIALS AND METHODS

Male Sprague-Dawley rats were randomized into four groups (n = 7 per group): control, uninephrectomy, IR group, and IR group pretreated with pravastatin (0.4 mg/kg/day for the preceding 5 days). Following a left nephrectomy the IR injury was induced by cross-clamping the right vascular pedicle for 30 min followed by reperfusion for 2 h. In a separate experiment (n = 6 per group) renal function was assessed 12 and 24 h after reperfusion.

RESULTS

IR injury causes significant renal dysfunction characterized by oliguria, 0.11 (0.05) ml/h, decreased glomerular filtration rate (GFR), 0.02 (0.01) ml/min; and marked protein leakage, 7.21 (1.3) g/L, 2 h postreperfusion. This renal dysfunction was also evident 12 and 24 h postreperfusion. This was in contrast to values of 0.61 (0.13) ml/h, 0.23 (0.01) ml/min, and 1.67 (0.12) g/L in the uninephrectomy-only group and values of 2 ml/h, 7.3 ml/min, and 0.72 g/L for uninjured time-matched controls. Pretreatment with pravastatin significantly attenuated IR-induced renal injury, improving urine production to 0.62 (0.2) ml/h and GFR to 0.14 (0.02) ml/min and diminishing protein leakage to 3.76 (0.7) g/L at the 2-h time point. This renoprotective effect was also evident 12 and 24 h postreperfusion. This renal protection was associated with an upregulation of constitutive endothelial nitric oxide synthase in the pravastatin-treated group.

CONCLUSION

These results show that pravastatin may play a role in modulating renal impairment following aortic or transplantation surgery, allowing earlier recovery from an IR injury.

Characterization of renal parenchymal perfusion during experimental infrarenal aortic clamping and declamping with enhanced thermodiffusion electrodes

Despite multiple previous experimental and clinical investigations, it has not been fully clarified until now whether infrarenal aortic cross-clamping (IRAC) induces a significant disturbance of renal parenchymal perfusion. Most renal cortical flow data collected thus far have been heterogenous because of inherent limitations of available measurement technology. The enhanced thermal diffusion (TD) electrode is a newly developed and previously validated prototype device that allows continuous quantification of parenchymal kidney perfusion after local probe implantation. We monitored renal perfusion during experimental IRAC with TD for the first time, thereby also evaluating the potential applicability of the method in clinical aortic surgery. IRAC (20 min) followed by sudden declamping was performed in pigs under general anesthesia (n = 14). Renal cortical blood flow (RCBF) was continuously quantified by TD, total aortic flow (TABF) and renal artery flow (RABF) were measured by ultrasonic flow probes, and parameters of systemic circulation were determined by Swan-Ganz catheter. Our results showed that kidney perfusion can be continuously quantified using TD electrodes during experimental aortic surgery in a porcine model. IRAC does not lead to a significant impairment of RCBF in young pigs as measured by TD. Renal perfusion appears to be predominantly pressure driven. Consequently, abrubt aortic declamping can bring about prolonged renal ischemia. Transfer of the TD method to RCBF monitoring during clinical aortic surgery appears to be feasible and should be investigated in selected cases.

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

Despite major advances in critical care medicine and extracorporeal renal support, the treatment of established postoperative ARF remains unsatisfactory and costly. The essential elements of perioperative renal preservation are early recognition of high-risk patients, preoperative optimization of fluid status and cardiovascular performance, intraoperative maintenance of renal perfusion, and avoidance of nephrotoxins. Pharmacologic interventions directed at preventing postoperative ARF are under intense investigation but presently are limited to renal transplant surgery.

Outcome in patients requiring renal replacement therapy after surgery for ruptured and non-ruptured aneurysm of the abdominal aorta

OBJECTIVES

to study the course of postoperative acute renal failure requiring renal replacement therapy (RRT) in patients with ruptured (RAAA) and non-ruptured (EAAA) aneurysm of the abdominal aorta (AAA) and to investigate the predictive value regarding outcome of parameters collected during the illness.

DESIGN

retrospective study in a university hospital.

MATERIALS AND METHODS

the records of 42 patients, 21 with RAAA and 21 with EAAA, were reviewed.

RESULTS

overall mortality was 69%, 71% for RAAA patients and 66% for EAAA patients. RRT was started 9 (2-28) days - median (range) - postoperatively and continued during 9 (2-50) days. Renal function recovered in nine of the 13 survivors after 18 (2-50) days. Length of ICU stay was 50 (2-132) days for survivors vs. 19 (6-56) days for non-survivors. The systemic inflammatory response syndrome (SIRS) or need for vasoactive support was associated with poor outcome and the ability to wean from vasoactive or ventilatory support with improved outcome.

CONCLUSIONS

RAAA and EAAA patients requiring postoperative RRT both had a high mortality. The ICU stay of non-survivors was shorter than that of survivors, who had a 75% chance of regaining renal function. The ability to wean from ventilatory and inotropic support may be of help in the clinical management of patients requiring RRT after AAA surgery.

Determinants of postoperative and long-term survival of patients with ruptured abdominal aortic aneurysms

To compare the surgical results of patients with ruptured (rAAA) and nonruptured abdominal aortic aneurysms (NrAAA), 267 consecutive patients surgically treated for abdominal aortic aneurysms (AAA) were reviewed. The patients' characteristics, preexistent risk factors, perioperative factors, and postoperative early and long-term survival were compared between the rAAA group (n = 27) and the NrAAA group (n = 240). A multivariate analysis to predict postoperative survival was also conducted in the rAAA group. The hospital mortality rate was 3.3% (8/232) for the NrAAA group and 22.2% (6/27) for the rAAA group (P < 0.001). The maximum size of aneurysms, period of preoperative hypotension, and intraoperative bleeding volume were significantly higher in the rAAA group than in the NrAAA group. The 5- and 10-year cumulative survival rates in the rAAA group were 88.1% and 42.0%, which were comparable to those in the NrAAA group. The incremental risk factors for hospital death in the rAAA group included advanced age, preoperative hypotension (< 80 mmHg), and postoperative renal failure requiring dialysis. These findings showed that the interval from rupture to cross-clamping must be shortened, maintaining hemodynamic stability to avoid prolonged hypotension. Reducing risk factors and minimizing deterioration of organ functions postoperatively would be essential to improve the prognosis of patients with rAAA.

Evaluation of dopexamine hydrochloride as a renoprotective agent during aortic surgery

Thirty-two patients undergoing elective infrarenal aortic surgery were randomly assigned to receive a perioperative infusion of either dopexamine hydrochloride at a rate of 2 micrograms/kg/min (n = 15) or 0.9% saline solution as placebo (n = 17). Renal function was monitored by regular measurements of serum creatinine levels. There were significant mean percentage increases in serum creatinine (p < 0.001) at all time points up to 3 days postoperatively in the placebo group but only at 2 and 12 hours in the dopexamine group. It was concluded that dopexamine hydrochloride confers renal protection in patients undergoing aortic reconstruction.

Outcome in patients who require renal support after surgery for ruptured abdominal aortic aneurysm

Over a 3-year period haemofiltration and dialysis was provided for 18 patients who developed renal failure after operation for ruptured abdominal aortic aneurysm (AAA). Four of the patients underwent operation elsewhere and were transferred when renal failure was diagnosed. The median duration of renal support in the 11 survivors was 24 days, while the seven patients who died received support for a median of 11 days. By 3 months after operation eight of the 11 survivors were independent of dialysis. Renal support was life saving in eight of 91 patients operated on in Oxford for ruptured AAA and reduced the 30-day operative mortality rate from a potential 47 per cent to an actual 38 per cent. Haemofiltration and haemodialysis for acute renal failure after surgery for ruptured aortic aneurysm is clinically justified and results in the long-term survival of most patients.

Abdominal aortic aneurysm surgery: survival and quality of life in patients requiring prolonged postoperative intensive therapy

The goal of this study was to identify patients who need longer care in the ICU (more than 48 hours) following abdominal aortic aneurysm (AAA) surgery and to evaluate the influence of perioperative complications on short- and long-term survival and quality of life. AAA surgery was performed in 553 patients, 51 (9%) of whom died within the first 48 hours. Of the 502 patients who survived for more than 48 hours, 109 required ICU therapy for more than 48 hours, whereas 393 patients were in the ICU for less than 48 hours. The incidence of preoperative risk factors was similar for the two groups. The cumulated survival rates for the two groups were 68% and 92% at 1 months, 52% and 88% at 1 year, and 60% and 33% at 6 years, respectively. This significant difference was primarily related to renal, pulmonary, and cardiac complications. However, assessment of the most severe complications and risk factors combined failed to permit identification of patients in whom the perioperative survival rate was 0%. Even 20% of patients with multiorgan failure survived for 6 months. Of those patients who needed ICU therapy for more than 48 hours, 41 (38%) were alive at the end of 1988. In response to a questionnaire, 78% stated that their quality of life had improved or was unchanged after surgery and had resumed working. These data justify a therapeutically aggressive approach, including ICU therapy following AAA surgery, despite failure of one or more organ systems.