Anesthetic technique and acute kidney injury in endovascular abdominal aortic aneurysm repair

Renal complications of anaesthesia

Peri-operative acute kidney injury is common, accounting for 30-40% of all in-hospital cases of acute kidney injury. It is associated with clinically significant morbidity and mortality even with what was hitherto regarded as relatively trivial increases in serum creatinine, and carries over a 12-fold relative risk of death following major abdominal surgery. Comorbid conditions such as diabetes, hypertension, liver disease and particularly pre-existing chronic kidney disease, as well as the type and urgency of surgery, are major risk factors for the development of postoperative acute kidney injury. As yet, there are no specific treatment options for the injured kidney, although there are several modifiable risk factors of which the anaesthetist should be aware. As well as the avoidance of potential nephrotoxins and appropriate volume balance, optimal anaesthetic management should aim to reduce the risk of postoperative renal complications. This may include careful ventilatory management and blood pressure control, as well as appropriate analgesic strategies. The choice of anaesthetic agent may also influence renal outcomes. Rather than concentrate on the classical management of acute kidney injury, this review focuses on the potential development of acute kidney injury peri-operatively, and the means by which this may be ameliorated.

Risk factors and early outcomes of acute renal injury after thoracic aortic endograft repair for type B aortic dissection

Background

Thoracic endovascular aortic repair (TEVAR) has become an emerging treatment modality for acute type B aortic dissection (TBAD) patients in recent years. The risk factors and impacts of acute kidney injury (AKI) after percutaneous TEVAR, however, have not been widely established.

Methods

We retrospectively studied the clinical records of 305 consecutive patients who admitted to our institution and had TEVAR for TBAD between December 2009 and June 2013. The patients were routinely monitored for their renal functions preoperatively until 7 days after TEVAR. The Kidney Disease Improving Global Guidelines (KDIGO) criteria were used for AKI.

Results

Of the total 305 consecutive patients, 84 (27.5%) developed AKI after TEVAR, comprising 66 (21.6%) patients in KDIGO stage 1, 6 (2.0%) patients in stage 2 and 12 (3.9%) patients in stage 3. From the logistic regression analysis, systolic blood pressure (SBP) on admission >140 mmHg (odds ratio [OR], 2.288; 95% CI, 1.319–3.969) and supra-aortic branches graft bypass hybrid surgery (OR, 3.228; 95% CI, 1.526–6.831) were independent risk factors for AKI after TEVAR. Local anesthesia tended to be a protective factor (OR, 0.563; 95% CI, 0.316–1.001). The preoperative renal function, angiotensin-converting enzyme inhibitor/angiotensin receptor blocker or statin administration, volume of contrast agent, range of TBAD and false lumen involving renal artery were not associated with post-operation AKI. The in-hospital mortality and major adverse events were markedly increased with the occurrence of AKI (7.1% vs 0.9%, P=0.006; 14.3% vs 3.2%, P<0.001, respectively).

Conclusions

TEVAR for TBAD has a high incidence of AKI, which is associated with worse in-hospital outcomes. SBP on admission and supra-aortic branches graft bypass hybrid surgery were the most significant risk factors. Renopreventive measures should be considered in high-risk patients.

The incidence, risk factors and in-hospital mortality of acute kidney injury in patients after abdominal aortic aneurysm repair surgery

Background

Acute kidney injury (AKI) is a severe complication associated with abdominal aortic aneurysm (AAA) repair. In this study, we evaluated the incidence, risk factors and in-hospital mortality of AKI in patients after the AAA repair surgery.

Methods

A total of 314 Chinese AAA patients who underwent endovascular aneurysm repair (EVAR) or open aneurysm repair (OPEN) were enrolled in this study. AKI was diagnosed according to the 2012 KDIGO criteria. Logistic regression modeling was used to explore risk factors of AKI, while risk factors associated with in-hospital mortality in AKI patients were investigated using Cox proportional hazards model and Kaplan-Meier analysis, respectively. Multicollinearity analysis was performed to identify the collinearity between the variables before logistic regression analysis and Cox proportional hazards analysis.

Results

Among 314 patients, 94 (29.9%) developed AKI after AAA repair surgery. Severity of AKI and ruptured AAA were independently associated with an increase in in-hospital mortality in AKI patients after AAA repair. Kaplan-Meier analysis identified severity of AKI as being negatively associated with hospital survival in AKI patients. Risk factors associated with AKI included cardiovascular disease (OR 3.169, 95% confidence interval (CI) 1.538 to 6.527, P = 0.002), decreased eGFR (OR 0.965, 95%CI 0.954 to 0.977, P < 0.001), ruptured AAA (OR 2.717, 95%CI 1.320 to 5.592, P = 0.007), renal artery involvement (OR 2.903, 95%CI 1.219 to 6.912, P = 0.016) and OPEN (OR 2.094, 95%CI 1.048 to 4.183, P = 0.036). Further subgroup analysis identified OPEN as an important risk factor of AKI in ruptured AAA patients but not in ruptured AAA patients. The incidence of AKI was significantly lower in EVAR than in OPEN (27.1% vs. 42.8%) and, similarly lower in nonruptured AAA than in ruptured AAA (26.2% vs. 48.1%).

Conclusion

One-third of AAA patients developed AKI after repair surgery. Severity of AKI was associated with reduced survival rate in AAA patients who developed postoperative AKI. Decreased preoperative creatinine clearance, cardiovascular disease, ruptured AAA and OPEN were independent risk factors for postoperative AKI in all 314 AAA patients. Although a lower rate of incident AKI was observed in EVAR compared with OPEN, subgroup analysis of ruptured AAA versus nonruptured AAA showed that EVAR was an independent protective factor for AKI only in ruptured AAA patients but not in nonruptured AAA patients.

Concurrent renal artery stent during endovascular infrarenal aortic aneurysm repair confers higher risk for 30-day acute renal failure

OBJECTIVE

Concurrent renal artery angioplasty and stenting (RAAS) during endovascular aneurysm repair (EVAR) of infrarenal abdominal aortic aneurysm (AAA) has been practiced in an attempt to maintain renal perfusion. The aim of this study was to identify the current practice of RAAS during EVAR and its effect on perioperative renal outcome.

METHODS

Patients with infrarenal AAA were identified from the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP, 2011-2014) database. Baseline characteristics of patients with concurrent RAAS during EVAR were compared with those of patients who underwent EVAR only. Bivariate and multivariable logistic regression analyses controlling for patients' demographics, comorbidities, and operative factors were used to evaluate the predictors of 30-day acute renal failure (ARF). Sensitivity analysis was done to evaluate the role of RAAS in patients with prior kidney disease.

RESULTS

Overall, 6183 patients underwent EVAR for infrarenal AAA during the study period. Of them, 281 patients had RAAS during EVAR (4.5%). The median age of the patients was 74 years; 81.7% of the cohort was male, but a higher proportion of female patients received EVAR + RAAS compared with patients who underwent EVAR only (26.3% vs 17.9%; P < .001). There was no difference between groups in terms of comorbidities, being on dialysis, or functional status, yet the EVAR + RAAS group had a higher proportion of patients with glomerular filtration rate <60 mL/min/1.73 m2 (45.2% vs 37.2%; P = .011). RAAS was associated with significantly higher odds for development of ARF (adjusted odds ratio [aOR], 4.27; 95% confidence interval [CI], 2.06-8.84; P < .001). Other highly predictive factors of 30-day ARF were glomerular filtration rate <60 (aOR, 2.92; 95% CI, 1.47-5.78; P = .002), emergency status (aOR, 2.97; 95% CI, 1.21-7.27; P = .017), and ruptured AAA as the indication for EVAR (aOR, 4.74; 95% CI, 1.80-12.50; P = .002). Patients with prior kidney disease who had EVAR + RAAS demonstrated a 12-fold higher odds for 30-day ARF (aOR, 12.37; 95% CI, 4.66-32.89; P < .001).

CONCLUSIONS

Concurrent RAAS was found to be a significant determinant of adverse renal outcomes after EVAR for infrarenal AAA. This effect was present even after controlling for patients' risk factors that might contribute to postoperative ARF.

Inflammatory response and renal function following endovascular repair of the descending thoracic aorta

PURPOSE

To evaluate inflammatory response and renal function after thoracic endovascular aortic repair (TEVAR) of lesions in the descending thoracic aorta.

METHODS

Thirty-two consecutive patients treated with TEVAR from January 2010 to August 2013 were enrolled in this prospective study. Two were excluded owing to dissecting thoracic aortic aneurysm (TAA) extending into the renal arteries with renal failure in one and a saccular TAA in which a multilayer flow-modulating stent was implanted in the other. This left 30 patients (28 men; mean age 68.8±5.9 years) with 28 TAAs, an aortic dissection, and an aortic ulcer for the analysis. Temperature and serum levels of white blood cells (WBCs), C-reactive protein (CRP), interleukin-10 (IL-10), IL-6, IL-8, tumor necrosis factor-alpha (TNF-α), creatinine, urea, and cystatin C were measured preoperatively and at 24 and 48 hours postoperatively.

RESULTS

Statistically significant increases in temperature and serum levels of WBCs, CRP, IL-10, and IL-6 were observed 24 and 48 hours postoperatively compared to baseline (all p<0.05). The number of endografts and the coverage of the celiac or subclavian artery did not affect the magnitude of the inflammatory response. No significant differences were observed concerning serum levels of IL-8, TNF-α, creatinine, or cystatin C from baseline to 24 or 48 hours postoperatively.

CONCLUSION

Endograft implantation in the thoracic aorta may propagate an inflammatory response during the early postoperative period. No clinical adverse events related to the increased inflammatory response were observed. Renal function does not seem to be deteriorated after TEVAR in the descending thoracic aorta.

Quantified Aortic Luminal Irregularity as a Predictor of Complications and Prognosis After Endovascular Aneurysm Repair

Atheromatous degeneration of the aorta is considered to be a risk factor for postoperative embolic complications after endovascular treatment, and is associated with a high incidence of vascular events in the long term. We devised a method to quantify the shagginess of the aorta using contrast-enhanced computed tomography (CT) images. This study examined the method's validity and prognostic usefulness in patients undergoing elective endovascular abdominal aortic aneurysm repair (EVAR). We retrospectively investigated 427 patients who underwent elective EVAR between 2007 and 2013. Preoperative contrast-enhanced CT images with a slice thickness of 1 mm were analyzed using a workstation, and the degree of aortic luminal irregularity from the level of the left subclavian artery ostium to that of the celiac artery ostium was quantified by computing a shagginess score. We compared the computed scores with subjective visual assessments of aortic shagginess. Subsequently, we evaluated the relationship between the computed scores and postoperative prognosis. The shagginess scores were significantly correlated with the visual assessments of the aortic lumen, which were performed by 5 experienced vascular surgeons (rho ranged from 0.564-0.654, all P < 0.001). Multiple logistic regression analysis demonstrated that the shagginess score was independently associated with the development of renal impairment within a month after EVAR (odds ratio, 2.78; 95% confidence interval [CI], 1.83-4.22, P < 0.001). The shagginess score was significantly higher in patients who suffered postoperative intestinal and peripheral ischemic complications, as compared with those who did not (P < 0.001). The mean postoperative follow-up period was 1207 ± 641 days. Cox proportional hazards regression showed that the shagginess score was a significant independent predictor of all-cause and cardiovascular mortality (hazard ratio [HR], 1.37; 95% CI, 1.09-1.72, P = 0.007, and HR, 1.51; 95% CI, 1.04-2.18, P = 0.030, respectively). The results suggest that the shagginess score provides a quantitative reflection of aortic luminal irregularity. It may serve as a useful predictive factor for postoperative renal function deterioration, embolic complications, and long-term mortality after elective EVAR.

Sedation or general anesthesia for transcatheter aortic valve implantation (TAVI)

Transfemoral transcatheter aortic valve implantation (TAVI) is nowadays a routine therapy for elderly patients with severe aortic stenosis (AS) and high perioperative risk. With growing experience, further development of the devices, and the expansion to "intermediate-risk" patients, there is increasing interest in performing this procedure under conscious sedation (TAVI-S) rather than the previously favoured approach of general anesthesia (TAVI-GA). The proposed benefits of TAVI-S include; reduced procedure time, shorter intensive care unit (ICU) length of stay, reduced need for intraprocedural vasopressor support, and the potential to perform the procedure without the direct presence of an anesthetist for cost-saving reasons. To date, no randomized trial data exists. We reviewed 13 non-randomized studies/registries reporting data from 6,718 patients undergoing TAVI (3,227 performed under sedation). Patient selection, study methods, and endpoints have differed considerably between published studies. Reported rates of in-hospital and longer-term mortality are similar for both groups. Up to 17% of patients undergoing TAVI-S require conversion to general anesthesia during the procedure, primarily due to vascular complications, and urgent intubation is frequently associated with hemodynamic instability. Procedure related factors, including hypotension, may compound preexisting age-specific renal impairment and enhance the risk of acute kidney injury. Hypotonia of the hypopharyngeal muscles in elderly patients, intraprocedural hypercarbia, and certain anesthetic drugs, may increase the aspiration risk in sedated patients. General anesthesia and conscious sedation have both been used successfully to treat patients with severe AS undergoing TAVI with similar reported short and long-term mortality outcomes. The authors believe that the significant incidence of complications and unplanned conversion to general anesthesia during TAVI-S mandates the start-to-finish presence of an experienced cardiac anesthetist in order to optimize patient outcomes. Good quality randomized data is needed to determine the optimal anesthetic regimen for patients undergoing TAVI.

Targets to prevent prolonged length of stay after endovascular aortic repair

OBJECTIVE

Endovascular aneurysm repair (EVAR) is a commonly performed vascular operation. Yet, postoperative length of stay (LOS) varies greatly, even within institutions. The present study reviewed the morbidity, mortality, and the financial effect of increased LOS to establish modifiable factors associated with prolonged hospital LOS, with the goal of improving quality.

METHODS

The Society for Vascular Surgery Vascular Quality Initiative database was used to identify all patients undergoing primary, elective EVAR at a single institution between January 1, 2011, and May 28, 2014. Preoperative patient characteristics, intraoperative details, postoperative factors, long-term outcomes, and cost data were reviewed using an Institutional Review Board-approved prospectively collected database. Multivariate analysis was used to determine statistical difference between patients with LOS ≤2 days and >2 days.

RESULTS

Complete 30-day variable and cost data were available for 138 patients with an average follow-up of 12 months; of these, 46 (33%) had a LOS >2 days. Variables determined to be statistically significant predictors of prolonged LOS included aneurysm diameter (P = .03), American Society of Anesthesiologists Physical Status Classification score (P < .001), thromboembolectomy (P = .01), and increased postoperative cardiac (P < .001) and renal (P = .01) complications. Specifically, modifiable risk factors that contributed to increased LOS included performance of a concomitant procedure (P < .001), increased volume of iodinated contrast (P = .05), increased volume of intraoperative crystalloid (P = .05), placement in an intensive care unit (P < .001), return to the operating room (P < .001), and the use of vasoactive medications (P < .001). Hospital charges ($102,000 ± $41,000 vs $180,000 ± $73,000; P = .01) and costs ($27,000 ± $10,000 vs $45,000 ± $19,000 P = .01) were significantly higher in patients with prolonged LOS; however, there was no difference in physician charges ($8000 ± $5700 vs $12,000 ± $12,000; P = .09). Increased LOS after EVAR was associated with an increase in mortality at 1 month (0% vs 4% P = .05) and 12 months (3% vs 13% P = .03).

CONCLUSIONS

This study highlights several modifiable risk factors leading to increased LOS after EVAR, including performance of concomitant procedures, admission to the intensive care unit, and postoperative renal and cardiac complications. Further, increased LOS was associated with increased charges, costs, morbidity, and mortality after EVAR. This study highlights specific areas of focus for decreasing LOS after EVAR and, in turn, improving quality in vascular surgery.