Cytokine activation and intestinal mucosal and renal dysfunction are reduced in endovascular AAA repair compared to surgery

The impact of endovascular repair of ruptured abdominal aortic aneurysm on the gastrointestinal and renal function

Introduction. Systemic effects of ruptured abdominal aortic aneurysm (rAAA) may be altered by the mode of surgery. This study aimed to determine systemic effects of endovascular aneurysm repair (EVAR) compared to open repair (OR). Patients and Methods. Consecutive patients with rAAA were repaired by OR or EVAR according to computerised tomographic (CT) findings. Renal function was monitored by estimated glomerular filtration rate (eGFR), serum urea and creatinine, and urinary albumin creatinine ratio (ACR). Hepatic function was assessed postoperatively for 5 days. Intestinal function was determined by the paracetamol absorption test. Intestinal permeability was assessed by urinary lactulose/mannitol ratio. Results. 30 rAAA patients were included. Fourteen had eEVAR and sixteen eOR. Serum urea were higher in eOR, while creatinine was similar between groups. Hepatic function showed no intergroup difference. Paracetamol absorption was increased in eEVAR group at day 3 compared to day 1 (P = 0.03), with no similar result in eOR (P = 0.24). Peak lactulose/mannitol ratio was higher in eOR (P = 0.03), with higher urinary L/M ratio in eOR at day 3 (P = 0.02). Clinical intestinal function returned quicker in eEVAR (P = 0.02). Conclusion. EVAR attenuated the organ dysfunction compared to open repair. However, a larger comparative trial would be required to validate this. The clinical trial is registered with reference number EUDRACT: 2013-003373-12.

Interventions for protecting renal function in the perioperative period

BACKGROUND

Various methods have been used to try to protect kidney function in patients undergoing surgery. These most often include pharmacological interventions such as dopamine and its analogues, diuretics, calcium channel blockers, angiotensin-converting enzyme (ACE) inhibitors, N-acetyl cysteine (NAC), atrial natriuretic peptide (ANP), sodium bicarbonate, antioxidants and erythropoietin (EPO).

OBJECTIVES

This review is aimed at determining the effectiveness of various measures advocated to protect patients' kidneys during the perioperative period.We considered the following questions: (1) Are any specific measures known to protect kidney function during the perioperative period? (2) Of measures used to protect the kidneys during the perioperative period, does any one method appear to be more effective than the others? (3) Of measures used to protect the kidneys during the perioperative period,does any one method appear to be safer than the others?

SEARCH METHODS

In this updated review, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 2, 2012), MEDLINE (Ovid SP) (1966 to August 2012) and EMBASE (Ovid SP) (1988 to August 2012). We originally handsearched six journals (Anesthesia and Analgesia, Anesthesiology, Annals of Surgery, British Journal of Anaesthesia, Journal of Thoracic and Cardiovascular Surgery, and Journal of Vascular Surgery) (1985 to 2004). However, because these journals are properly indexed in MEDLINE, we decided to rely on electronic searches only without handsearching the journals from 2004 onwards.

SELECTION CRITERIA

We selected all randomized controlled trials in adults undergoing surgery for which a treatment measure was used for the purpose of providing renal protection during the perioperative period.

DATA COLLECTION AND ANALYSIS

We selected 72 studies for inclusion in this review. Two review authors extracted data from all selected studies and entered them into RevMan 5.1; then the data were appropriately analysed. We performed subgroup analyses for type of intervention, type of surgical procedure and pre-existing renal dysfunction. We undertook sensitivity analyses for studies with high and moderately good methodological quality.

MAIN RESULTS

The updated review included data from 72 studies, comprising a total of 4378 participants. Of these, 2291 received some form of treatment and 2087 acted as controls. The interventions consisted most often of different pharmaceutical agents, such as dopamine and its analogues, diuretics, calcium channel blockers, ACE inhibitors, NAC, ANP, sodium bicarbonate, antioxidants and EPO or selected hydration fluids. Some clinical heterogeneity and varying risk of bias were noted amongst the studies, although we were able to meaningfully interpret the data. Results showed significant heterogeneity and indicated that most interventions provided no benefit.Data on perioperative mortality were reported in 41 studies and data on acute renal injury in 44 studies (all interventions combined). Because of considerable clinical heterogeneity (different clinical scenarios, as well as considerable methodological variability amongst the studies), we did not perform a meta-analysis on the combined data.Subgroup analysis of major interventions and surgical procedures showed no significant influence of interventions on reported mortality and acute renal injury. For the subgroup of participants who had pre-existing renal damage, the risk of mortality from 10 trials (959 participants) was estimated as odds ratio (OR) 0.76, 95% confidence interval (CI) 0.38 to 1.52; the risk of acute renal injury (as reported in the trials) was estimated from 11 trials (979 participants) as OR 0.43, 95% CI 0.23 to 0.80. Subgroup analysis of studies that were rated as having low risk of bias revealed that 19 studies reported mortality numbers (1604 participants); OR was 1.01, 95% CI 0.54 to 1.90. Fifteen studies reported data on acute renal injury (criteria chosen by the individual studies; 1600 participants); OR was 1.03, 95% CI 0.54 to 1.97.

AUTHORS' CONCLUSIONS

No reliable evidence from the available literature suggests that interventions during surgery can protect the kidneys from damage. However, the criteria used to diagnose acute renal damage varied in many of the older studies selected for inclusion in this review, many of which suffered from poor methodological quality such as insufficient participant numbers and poor definitions of end points such as acute renal failure and acute renal injury. Recent methods of detecting renal damage such as the use of specific biomarkers and better defined criteria for identifying renal damage (RIFLE (risk, injury, failure, loss of kidney function and end-stage renal failure) or AKI (acute kidney injury)) may have to be explored further to determine any possible benefit derived from interventions used to protect the kidneys during the perioperative period.

Effects of study design and trends for EVAR versus OSR

Purpose:

To investigate if study design factors such as randomization, multi-center versus single center evidence, institutional surgical volume, and patient selection affect the outcomes for endovascular repair (EVAR) versus open surgical repair (OSR). Finally, we investigate trends over time in EVAR versus OSR outcomes.

Methods:

Search strategies for comparative studies were performed individually for: OVID’s MEDLINE, EMBASE, CINAHL, HAPI, and Evidence Based Medicine (EBM) Reviews (including Cochrane DSR, ACP Journal Club, DARE and CCTR), limited to 1990 and November 2006.

Results:

Identified literature: 84 comparative studies pertaining to 57,645 patients. These include 4 randomized controlled trials (RCTs), plus 2 RCTs with long-term follow-up. The other 78 comparative studies were nonrandomized with 75 reporting perioperative outcomes, of which 16 were multi-center, and 59 single-center studies. Of the single-center studies 31 were low-volume and 28 were high-volume centers. In addition, 5 studies had all patients anatomically eligible for EVAR, and 8 studies included high-risk patients only. Finally, 25 long term observational studies reported outcomes up to 3 years.

Outcomes:

Lower perioperative mortality and rates of complications for EVAR versus OSR varied across study designs and patient populations. EVAR adverse outcomes have decreased in recent times.

Conclusion:

EVAR highlights the problem of performing meta-analysis when the experience evolves over time.

Interventions for protecting renal function in the perioperative period

BACKGROUND

A number of methods have been used to try to protect kidney function in patients undergoing surgery. These include the administration of dopamine and its analogues, diuretics, calcium channel blockers, angiotensin converting enzyme inhibitors and hydration fluids.

OBJECTIVES

For this review, we selected randomized controlled trials which employed different methods to protect renal function during the perioperative period. In examining these trials, we looked at outcomes that included renal failure and mortality as well as changes in renal function tests, such as urine output, creatinine clearance, free water clearance, fractional excretion of sodium and renal plasma flow.

SEARCH STRATEGY

We searched the Cochrane Central register of Controlled Trials (CENTRAL) (The Cochrane Library 2007, Issue 2), MEDLINE (1966 to June, 2007), and EMBASE (1988 to June, 2007); and handsearched six journals (Anesthesia and Analgesia, Anesthesiology, Annals of Surgery, British Journal of Anaesthesia, Journal of Thoracic and Cardiovascular Surgery, and Journal of Vascular Surgery).

SELECTION CRITERIA

We selected all randomized controlled trials in adults undergoing surgery where a treatment measure was used for the purpose of renal protection in the perioperative period.

DATA COLLECTION AND ANALYSIS

We selected 53 studies for inclusion in this review. As well as data analysis from all the studies, we performed subgroup analysis for type of intervention, type of surgical procedure, and pre-existing renal dysfunction. We undertook sensitivity analysis on studies with high and moderately good methodological quality.

MAIN RESULTS

The review included data from 53 studies, comprising a total of 2327 participants. Of these, 1293 received some form of treatment and 1034 acted as controls. The interventions mostly consisted of different pharmaceutical agents, such as dopamine and its analogues, diuretics, calcium channel blockers, ACE inhibitors, or selected hydration fluids. The results indicated that certain interventions showed minimal benefits. All the results suffered from significant heterogeneity. Hence we cannot draw conclusions about the effectiveness of these interventions in protecting patients' kidneys during surgery.

AUTHORS' CONCLUSIONS

There is no reliable evidence from the available literature to suggest that interventions during surgery can protect the kidneys from damage. There is a need for more studies with high methodological quality. One particular area for further study may be patients with pre-existing renal dysfunction undergoing surgery.

Role of the Hardman index in predicting mortality for open and endovascular repair of ruptured abdominal aortic aneurysm

PURPOSE

To correlate the Hardman prognostic index with perioperative mortality in patients undergoing open and endovascular repair of ruptured abdominal aortic aneurysm (rAAA).

METHODS

Over a 5-year period, 126 patients (109 men; mean age 74 years, range 51-91) underwent open (n=74) or endovascular (n=52) repair of rAAA in a single unit. Five Hardman factors (age>76 years, history of loss of consciousness, ECG evidence of ischemia, hemoglobin<9.0 g/dL, and serum creatinine>0.19 mmol/L) were assessed, and their association with in-hospital or 30-day mortality was evaluated retrospectively by chi-square or logistic regression analysis.

RESULTS

The mortality for open repair was 51.4% (38/74) in comparison to 32.7% (17/52) for the endovascular group (p=0.05). On multivariate analysis, loss of consciousness (p=0.03, OR 2.9, 95% CI 1.1 to 7.5) was the only significant predictor of mortality in both groups. The mortality rates for open repair patients with Hardman scores<2 were 43.5% (20/46) in comparison to 22.9% (8/35) for the endovascular group (p=0.06), whereas mortality rates for patients with scores>or=2 were 64.3% (18/28) and 52.9% (9/17) for the respective groups (p=0.54).

CONCLUSION

The Hardman index correlates well with mortality in both the open and endovascular groups. Those with a score<2 have a trend toward better survival following endovascular repair compared to open repair, while this benefit is not obvious in patients with a score>or=2.

Incidence and Effect of Bare Suprarenal Stent Struts Crossing Renal Ostia Following EVAR

OBJECTIVES

The incidence and effect of bare stent struts crossing the renal ostia following endovascular aortic aneurysm repair with the Talent stent-graft is not known. The study aims to establish the incidence in which bare stent struts cross the renal ostia and to assess any associated effects on renal function.

METHODS

Fifty-five patients (51 men, mean age 73 years, range 57-90) who had endovascular repair of their abdominal aortic aneurysms with a Talent suprarenal stent-graft were included in the study. Patients were scanned at a variety of follow-up periods (median 24 months, range 3-102). The relationship between the bare stent struts and the renal ostia, together with renal function were retrospectively recorded. The presence and location of the bare stent struts was assessed using CT virtual intravascular endoscopy (CT VIE). Struts were defined as being absent, peripherally located or in the central channel of the renal ostia. Renal function was assessed from glomerular filtration rates (GFR) derived from serum creatinine levels and the Cockcroft and Gault formula.

RESULTS

A total of 109 renal ostia were evaluated by CT VIE with one patient having a previous nephrectomy. Bare stent struts crossed 1 renal ostium in 22 (40%) patients and bilateral ostia in 5 (9%) patients. Of the 109 ostia assessed, 15 (14%) ostia were crossed centrally and 17 (16%) had struts crossing the ostium peripherally. There were no statistically significant differences in the change between pre-operative GFR and latest GFR in the group without any strut involvement (6 mLs/min +/- 7 mLs/min) and the group with struts crossing one or both renal ostia (2 mLs/min +/- 9 mLs/min; p > .05).

CONCLUSION

Peripheral or central coverage of renal ostia by bare stent struts occurs in a third of all renal arteries following EVAR. Crossing of renal ostia by bare stent struts does not affect follow-up GFR.

An intention-to-treat by endovascular repair policy may reduce overall mortality in ruptured abdominal aortic aneurysm

OBJECTIVE

The use of endovascular aneurysm repair (EVAR) for ruptured abdominal aortic aneurysm (AAA) has been restricted to a small number of specialized units on a selected group of patients. The aim of this study is to assess if the overall mortality in these patients with ruptured AAA may be reduced in a unit where all patients with ruptured AAA are considered first for EVAR.

METHODS

During a 24-month period beginning in July 2002, 51 patients admitted with ruptured AAA were considered for EVAR as the treatment of choice and comprised the study group. EVAR was performed in 17 patients. Open repair was performed in 34 patients: 13 patients had hemodynamic instability and 16 patients had an unsuitable aortic neck anatomy. The study group was compared with a historical control group of 41 patients with ruptured AAA who were treated by open repair from July 2000 to June 2002.

RESULTS

Mortality rate was 39% in the study group compared with 59% in the control group (P = .065). The duration of stay in the intensive care unit was significantly lower in the study group than in the control group (P = .01), although the total in-hospital stay was similar (17 days vs 14 days, P = .83). Within the study group, EVAR patients had a mortality rate of 24% compared with 47% in the open group (P = .14).

CONCLUSION

Although the number of patients was small, offering EVAR to as many patients as possible with ruptured AAA has resulted in a 20% reduction in mortality, albeit statistically insignificant. However, it is in the unstable patients that EVAR will need to improve survival before it may be hailed to supersede the conventional approach.