General versus loco‐regional anesthesia for endovascular aortic aneurysm repair

Abstract

Background

Aortic aneurysms occur when the aorta, the body's largest artery, grows in size, and can occur in the thoracic or abdominal aorta. The approaches to repair aortic aneurysms include directly exposing the aorta and replacing the diseased segment via open repair, or endovascular repair. Endovascular repair uses fluoroscopic‐guidance to access the aorta and deliver a device to exclude the aneurysmal aortic segment without requiring a large surgical incision. Endovascular repair can be performed under a general anesthetic, during which the unconscious patient is paralyzed and reliant on an anesthetic machine to maintain the airway and provide oxygen to the lungs, or a loco‐regional anesethetic, for which medications are administered to provide the person with sufficient sedation and pain control without requiring a general anesthetic. While people undergoing general anesthesia are more likely to remain still during surgery and have a well‐controlled airway in the event of unanticipated complications, loco‐regional anesthesia is associated with fewer postoperative complications in some studies. It remains unclear which anesthetic technique is associated with better outcomes following the endovascular repair of aortic aneurysms.

Objectives

To evaluate the benefits and harms of general anesthesia compared to loco‐regional anesthesia for endovascular aortic aneurysm repair.

Search methods

We used standard, extensive Cochrane search methods. The latest search was 11 March 2022.

Selection criteria

We searched for all randomized controlled trials that assessed the effects of general anesthesia compared to loco‐regional anesthesia for endovascular aortic aneurysm repairs.

Data collection and analysis

We used standard Cochrane methods. Our primary outcomes were: all‐cause mortality, length of hospital stay, length of intensive care unit stay. Our secondary outcomes were: incidence of endoleaks, requirement for re‐intervention, incidence of myocardial infarction, quality of life, incidence of respiratory complications, incidence of pulmonary embolism, incidence of deep vein thrombosis, and length of procedure. We planned to use GRADE methodology to assess the certainty of evidence for each outcome.

Main results

We found no studies, published or ongoing, that met our inclusion criteria.

Authors' conclusions

We did not identify any randomized controlled trials that compared general versus loco‐regional anesthesia for endovascular aortic aneurysm repair. There is currently insufficient high‐quality evidence to determine the benefits or harms of either anesthetic approach during endovascular aortic aneurysm repair. Well‐designed prospective randomized trials with relevant clinical outcomes are needed to adequately address this.

Plain language summary

Is general anesthesia or loco‐regional anesthesia better for people needing an endovascular repair of an aortic aneurysm?

Key messages

‐ we did not find any randomized controlled trials to help answer our question

‐ there is a need for high‐quality evidence to compare the benefits and harms of general anesthesia compared to loco‐regional anesthesia in people undergoing endovascular repair of an aortic aneurysm

What is an aortic aneurysm?

When the diameter of arteries or veins grows beyond a certain size, they are known as aneurysms. Aneurysms that continue to grow beyond a certain size are at risk of bursting. The aorta is the largest artery in the body, and people with a burst aortic aneurysm are at a high risk of experiencing severe complications, such as death.

How are aortic aneurysms treated?

In order to treat, or repair, an aortic aneurysm, the surgeon could cut into the person's chest and abdomen to expose the aneurysm, and replace it with a synthetic material, known as a graft. This is called open aortic aneurysm repair. Another option is for the surgeon to use an x‐ray (or similar technology) to guide them as they insert the graft through small cuts in the person's arteries, and avoid the need for a big surgical cut. This is known as endovascular aortic aneurysm repair.

People who undergo an endovascular aortic aneurysm repair can have a general anesthetic, during which they are placed in a temporary coma and depend on a machine to breathe (commonly called put to sleep). The advantages for this anesthetic approach are that the anesthetist can control the person's airway, and the surgeon knows that the person won't move during the delicate phases of the surgery. However, there is also a risk of low blood pressure, blood clots, and breathing problems during or after surgery. Alternatively, people can receive medicines to control the pain and anxiety of surgery without going to sleep. This is known as loco‐regional anesthesia. The advantage of this approach is that the person avoids the risks of general anesthesia. However, loco‐regional anesthesia requires that the person fully co‐operates during the surgery and lies still, and being awake during the surgery may cause them significant discomfort.

What did we want to find out?

We wanted to find out if there were any benefits or harms of general anesthesia compared to loco‐regional anesthesia for people who are having an endovascular repair of an aortic aneurysm.

What did we do?

We searched for all randomized studies that compared the use of general anesthesia to loco‐regional anesthesia use in people who needed an endovascular repair of an aortic aneurysm. In randomized controlled trials, the treatments people receive are decided at random, and these give the most reliable evidence about treatment effects.

What did we find?

We did not find any randomized controlled trials that met the inclusion criteria for our review. As such, it is not possible to draw conclusions about the benefits or harms of general anesthesia compared with loco‐regional anesthesia for endovascular treatment of aortic aneurysms. This means there is a need for randomized controlled trials to provide evidence of any benefits or harms to help guide decision‐making.

How up‐to‐date is this evidence?

This evidence is current to 11 March 2022.

Background

Description of the condition

An aneurysm occurs when a blood vessel enlarges by more than 50% of its normal expected diameter (Kent 2014). They can occur in any artery or vein in the body, and carry an increased risk of complications, such as rupture, which can sometimes be fatal. The aorta is the largest artery in the body, and aortic aneurysms can occur in the chest or in the abdomen. Aneurysms that occur in the segment of aorta contained within the chest are known as thoracic aortic aneurysms. The incidence of aortic aneurysms is 16 out of 100,000 males and 9 out of 100,000 females per year (Olsson 2006). Abdominal aortic aneurysms are more prevalent, and occur in up to 8% of males (Singh 2001). When they reach a certain diameter threshold, aortic aneurysms should be repaired to prevent the risk of complications (Gloviczki 2018).

Options for aneurysm treatment include creating an incision in the chest or abdomen and replacing the aneurysmal segment using a prosthetic graft (known as an open repair), or excluding aortic blood flow and pressure from the aneurysm using a graft, which is placed under fluoroscopic (or x‐ray) guidance (known as an endovascular repair). The majority of aortic aneurysms are currently repaired using an endovascular repair (Suckow 2018). The advantages of endovascular aneurysm repair include a reduction in short‐term mortality and perioperative complication rates compared with open repair (Paravastu 2014). Short‐term quality of life is also significantly higher in people who undergo endovascular aortic aneurysm repair, compared with open repair (Kayssi 2015). However, the incidence of postoperative cardiac events is not lower in people receiving endovascular aortic aneurysm repair (Thomas 2015). Endovascular aneurysm repair typically involves accessing the person's blood vessels at the groin by either exposing these vessels surgically, or by using ultrasound guidance to advance the endovascular graft into the vessels.

Description of the intervention

People undergoing endovascular aortic aneurysm repair receive either a general or a loco‐regional anesthetic before sheaths, wires, and catheters are introduced fluoroscopically, to assist in the deployment of the endovascular graft. General anesthesia refers to administering anesthetic medications to people, who then enter a reversible comatose state and require ventilator support through an endotracheal tube, a device that is inserted directly into the trachea, or through a laryngeal mask airway, a device that maintains an open airway by sealing the glottic opening. Loco‐regional anesthesia includes topical anesthesia, for which people receive a subcutaneous injection (injection under the skin) of local anesthetic to numb the skin before the procedure is started, or regional anesthesia, such as spinal or epidural anesthesia. In both approaches, low‐dose, mild, and intravenous sedatives can be given if necessary. The advantages of regional anesthesia include less stress and inflammatory responses, avoidance of mechanical ventilation, and adequate postoperative analgesia (Kothandan 2016). However, it is unclear whether loco‐regional anesthesia is associated with significant differences in perioperative outcomes compared with general anesthesia.

How the intervention might work

In deciding whether to administer a loco‐regional versus a general anesthetic to a person undergoing endovascular aneurysm repair, the anesthetist must consider several factors, including the person's cardiopulmonary status, other medical comorbidities, and their ability to lie still during surgery (Kothandan 2016). Possible advantages of loco‐regional anesthesia include avoiding the need to intubate the airway, and decreasing the risk of cardiac and pulmonary complications, especially in the high‐risk vascular surgery population (Bakker 2012). In some cases, people have such severe cardiovascular disease or compromised respiratory function that the risk of a general anesthetic causing a perioperative complication is too great, and so anesthetists favor a loco‐regional strategy. However, people undergoing surgery with a loco‐regional anesthetic are more likely to move during the procedure due to discomfort, which may make the surgery more challenging, and people who receive an epidural may require prolonged bladder catheterization, due to the greater risk of urinary retention with this anesthetic strategy (Baldini 2009; Spielman 1985).

Why it is important to do this review

It is unclear whether loco‐regional and general anesthesia are associated with different outcomes for endovascular aneurysm repair. This question is important to ask because it has several implications. If outcomes after loco‐regional anesthesia are equivalent or non‐inferior to those with general anesthesia, more anesthetists might consider loco‐regional anesthesia for endovascular aneurysm repair, in order to avoid the known complications associated with general anesthesia, such as heart failure, myocardial infarction, aspiration, and postoperative cognitive dysfunction (Harris 2013). Conversely, if general anesthesia is associated with fewer complications, this might encourage more anesthetists to perform more endovascular aneurysm repairs using general anesthesia.

Objectives

To evaluate the benefits and harms of general compared to loco‐regional anesthesia for endovascular aortic aneurysm repair.

Methods

Criteria for considering studies for this review

Types of studies

We considered randomized controlled trials (RCTs) that compared the use of general anesthesia versus loco‐regional anesthesia for endovascular aortic aneurysm repair.

Types of participants

We planned to include studies with participants undergoing endovascular abdominal or thoracic aortic aneurysm repair, using either general or loco‐regional anesthesia, including spinal or epidural anesthesia.

Types of interventions

We planned to include studies that compared general anesthesia to loco‐regional anesthesia in participants undergoing elective and emergency procedures, as well as those undergoing complex endovascular aortic aneurysm repair.

Types of outcome measures

Primary outcomes

• 30‐day all‐cause perioperative mortality

• Length of hospital stay, in days

• Length of intensive care unit stay, in days

Secondary outcomes

• Incidence of endoleaks

• Requirement for re‐intervention

• Incidence of myocardial infarction

• Quality of life, reported using validated scales (such as the 36‐Item Short Form Survey (SF‐36), or the EuroQol‐5D (EQ‐5D))

• Incidence of respiratory complications (such as atelectasis, aspiration, pneumonia, or bronchospasm)

• Incidence of pulmonary embolism (assessed by pulmonary angiography)

• Incidence of deep vein thrombosis (assessed by Doppler ultrasound or compression ultrasound)

• Length of procedure, in hours

Search methods for identification of studies

Electronic searches

The Cochrane Vascular Information Specialist conducted systematic searches of the following databases, for randomized controlled trials and controlled clinical trials without language, publication year, or publication status restrictions:

• the Cochrane Vascular Specialised Register via the Cochrane Register of Studies (CRS‐Web);

• the Cochrane Central Register of Controlled Trials (CENTRAL; 2022, Issue 3) via the Cochrane Register of Studies Online (CRSO);

• MEDLINE (Ovid MEDLINE Epub Ahead of Print, In‐Process & Other Non‐Indexed Citations, Ovid MEDLINE Daily, and Ovid MEDLINE

• Embase Ovid;

• CINAHL EBSCO.

The Information Specialist developed search strategies for other databases from the search strategy designed for MEDLINE. Where appropriate, they were combined with adaptations of the highly sensitive search strategy designed by Cochrane to identify randomized controlled trials and controlled clinical trials (described in the Cochrane Handbook for Systematic Reviews of Interventions (Lefebvre 2022)). Search strategies for major databases are provided in Appendix 1.

We searched the following trials registries

• World Health Organization International Clinical Trials Registry Platform (who.int/trialsearch);

• ClinicalTrials.gov (clinicaltrials.gov).

The most recent searches were carried out on 11 March 2022.

Searching other resources

We examined the bibliographies of relevant articles identified in our search, such as reviews and meta‐analyses, in order to identify additional reports.

Data collection and analysis

Selection of studies

Two review authors (SL, CY) independently screened all titles and abstracts identified from the searches to identify those that might meet the inclusion criteria. We retrieved the full text of studies identified as potentially relevant by at least one author. The same review authors independently screened the full‐text articles for inclusion or exclusion. The trials were assessed by a third review author (AD), who determined their suitability and adjudicated any disagreement between the first two authors, if necessary. We illustrated the study selection process in a PRISMA diagram (Liberati 2009). The inclusion criteria we used to determine suitability are outlined in the section Criteria for considering studies for this review.

Data extraction and management

Had we identified studies to include, we planned for two review authors (SL, CY) to independently extract relevant data from the studies onto a data collection form (piloted). We planned to collect the following information.

• Methods (study design, number of participants, exclusions post‐randomization, dropouts, losses to follow‐up, intention‐to‐treat analysis, duration/dates study conducted)

• Participants (country, setting, age, sex, inclusion criteria, exclusion criteria, number of participants randomized and analyzed, number and reason for withdrawal)

• Interventions (intervention group and sample size, type of anesthetic, comparator group, and sample size, including intervention type and adjunct treatments)

• Outcomes (definition and times outcomes were assessed, duration of follow‐up)

• Funding source and declarations of interest of study authors

We planned for a third review author (AD) to cross‐check the data. We intended to undertake a statistical analysis that complied with the standard methods of Cochrane Vascular, and use the computer software package RevMan Web 2022 to perform all statistical analyzes, and generate figures.

Assessment of risk of bias in included studies

Had we identified studies to include, we planned for two review authors (SL, CY) to independently undertake a thorough risk of bias assessment of all included studies, using Cochrane's RoB 1 tool (Higgins 2017). The tool assesses bias in seven different domains, with each domain receiving a rating of high, low, or unclear risk of bias, depending on each review author’s judgment. We planned for disagreements to be adjudicated by a third review author (AD). We intended to contact study authors if clarification was required to better assess risk of bias.

Measures of treatment effect

Had we included studies, we planned to calculate and report continuous outcome measures, such as length of hospital stay, using the mean difference (MD) or standardized mean difference (SMD) and associated 95% confidence interval (CI) between the two treatment groups. We also planned to calculate and report binary (dichotomous) outcome measures, such as the incidence of perioperative mortality, using the odds ratio (OR) or relative risk (RR) with the associated 95% CI, depending on the available reported data.

Unit of analysis issues

Had we included studies, we planned for the unit of analysis to be the individual person for all procedural outcomes.

Dealing with missing data

Had we included studies, we planned to contact study authors to inquire about missing or incomplete data, as required. If an included study had > 20% of missing data, and attempts to contact the study authors were unsuccessful, we planned to assess the risk of bias associated with including the study in the meta‐analysis, and perform a sensitivity analysis (Higgins 2022). When possible, we planned to carry out our analysis using an intention‐to‐treat approach.

Assessment of heterogeneity

Had we included studies, we planned to assess inter‐study heterogeneity visually, using a forest plot (Schünemann 2022). We also planned to use Chi² and I² tests to measure the amount of heterogeneity (Higgins 2003). We also planned to consider the magnitude and direction of effect. I² values of less than 40% might not be important, I² values between 30% and 60% may represent moderate heterogeneity, I² values between 50% and 90% may represent substantial heterogeneity, and I² values greater than 75% indicate considerable heterogeneity (Higgins 2022). When heterogeneity was detected, we planned to investigate possible reasons for this variability.

Assessment of reporting biases

If 10 or more studies were available for a particular outcome, we planned to construct a funnel plot to assess publication bias (Page 2022).

Data synthesis

We planned to carry out a meta‐analysis when the included trials were similar enough to allow meaningful conclusions from a statistically pooled result. To calculate the pooled treatment effect, we planned to use random‐effects or fixed‐effect models, depending on the degree of inter‐study heterogeneity. If the calculated degree of inter‐study heterogeneity was considerable (defined as an I² value greater than 75%), we planned to use the random‐effects model. Otherwise, we planned to use the fixed‐effect model. We also planned to calculate 95% CIs for continuous and dichotomous outcome variables, as detailed above, and to create a forest plot for each treatment effect, according to Cochrane guidelines (Higgins 2022). We did not do this, as we did not include any studies.

Subgroup analysis and investigation of heterogeneity

We planned to perform subgroup analyses of available data to compare results from participants receiving percutaneous access versus those receiving vessel cut‐downs for endovascular aortic aneurysmal repair. We also planned to subdivide loco‐regional anesthesia groups into local anesthesia (e.g. topical anesthesia with intravenous sedation) and regional anesthesia (e.g. spinal or epidural anesthesia), and compare these with general anesthesia (standard induction and maintenance agents). We also planned to consider the type of aneurysm repair (thoracic versus abdominal), and to consider the indication for surgery (elective versus emergency surgery), and the complexity of the aortic repair (branched and fenestrated grafts). Finally, we planned to perform a subgroup analysis based on the year of study publication, in order to assess the impact of the evolution of endovascular aneurysm repair practices on study endpoints. We did not do this, as we did not include any studies.

We planned to report the formal test for subgroup differences in Review Manager Web, to indicate whether there were clinically meaningful subgroup differences. We are aware that findings from multiple subgroup analyses can be misleading, especially when there are small numbers of included studies. We planned to consider this when reporting the findings (Higgins 2022).

Sensitivity analysis

We intended to use sensitivity analyses to determine if the results of our analyses were robust. We planned to exclude studies with a high risk for bias from the pooled analyses, and to perform the analyses again to assess the impact of these studies on the results. We defined high risk of bias as a study having two or more domains that were deemed to be at high risk of bias using the Cochrane RoB 1 tool. We also intended to exclude studies with > 20% of missing data in a sensitivity analysis.

Summary of findings and assessment of the certainty of the evidence

Had we included studies, we intended to prepare a summary of findings table, using GRADEpro GDT software (Schünemann 2016), to present the main findings of the review for the main comparisons, at the time point when the most relevant data were available from the included studies (Atkins 2004). We intended for the population to consist of participants undergoing endovascular aortic aneurysm repair with either general or loco‐regional anesthesia. We intended to include the following outcomes that we considered essential for decision‐making in our summary of findings table:

• 30‐day all‐cause perioperative mortality

• length of hospital stay

• length of intensive care unit stay

• incidence of endoleaks

• requirement for re‐intervention

• incidence of myocardial infarction

• quality of life

We planned to evaluate the certainty of the evidence using the GRADE approach (Schünemann 2022b), and to assign one of four levels of certainty — high, moderate, low, or very low — based on overall risk of bias, directness of the evidence, inconsistency of results, precision of the estimates, and risk of publication bias, described in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2022). A sample summary of findings table is shown in Table 1.

1. Sample summary of findings table: general anesthesia compared to loco‐regional anesthesia for endovascular aortic aneurysm repair.

Summary of findings: general anesthesia compared to loco‐regional anesthesia for endovascular aortic aneurysm repair
Patient or population: people undergoing endovascular aortic aneurysm repair Setting: hospital Intervention: general anesthesia Comparison: loco‐regional anesthesia
Outcomes	Anticipated absolute effects* (95% CI)		Relative effect (95% CI)	№ of participants (RCTs)	Certainty of the evidence (GRADE)	Comments
	Risk with loco‐regional anesthesia	Risk with general anesthesia
30‐day all‐cause perioperative mortality	The mean 30‐day all‐cause perioperative mortality was 0	The mean 30‐day all‐cause perioperative mortality in the intervention group was 0 (0 to 0)		(RCTs)
Length of hospital length of stay (days)	The mean hospital length of stay was 0	The mean hospital length of stay in the intervention group was 0 (0 to 0)		(RCTs)
Length of intensive care unit stay (days)	The mean intensive care unit length of stay was 0	The mean intensive care unit length of stay in the intervention group was 0 (0 to 0)		(RCTs)
Incidence of endoleaks (follow‐up)	The mean incidence of endoleaks was 0	The mean incidence of endoleaks in the intervention group was 0 (0 to 0)		(RCTs)
Requirement for re‐intervention (follow‐up)	0 per 1000	0 per 1000 (0 to 0)		(RCTs)
Incidence of myocardial infarction (follow‐up)	The mean incidence of myocardial infarction was 0	The mean incidence of myocardial infarction in the intervention group was 0 (0 to 0)		(RCTs)
Quality of life (measured with validated scales, follow‐up)	The mean quality of life was 0	The mean quality of life in the intervention group was 0 (0 to 0)		(RCTs)
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: Confidence interval; RCTs: randomized controlled trials
GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect Moderate certainty: we are moderately confident in the effect estimate; the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different Low certainty: our confidence in the effect estimate is limited; the true effect may be substantially different from the estimate of the effect Very low certainty: we have very little confidence in the effect estimate; the true effect is likely to be substantially different from the estimate of effect

Results

Description of studies

The results of the search are outlined in Figure 1.

1.

PRISMA study selection flow diagram

Results of the search

We did not find any randomized controlled trials (RCTs) to include. Database searches identified 1837 reports. After removing duplicates, we assessed 1565 reports by title and abstract screening; 15 of which we assessed by full‐text.

We did not identify any studies that met our inclusion criteria, and we did not re‐assess any studies that we then excluded. No relevant ongoing studies were found in the World Health Organization International Clinical Trials Registry Platform or the ClinicalTrials.gov database.

Included studies

We did not identify any randomized controlled trials that met our inclusion criteria.

Excluded studies

We did not identify any excluded studies.

Risk of bias in included studies

No studies met the review eligibility criteria, so it was not possible to assess risk of bias.

Effects of interventions

We did not include any RCTs, so it was not possible to investigate the benefits or harms of general versus loco‐regional anesthesia for endovascular aortic aneurysm repair.

Discussion

Summary of main results

We did not identify any randomized controlled trials that assessed the effects of general versus loco‐regional anesthesia for endovascular aortic aneurysm repair.

Overall completeness and applicability of evidence

There is insufficient high‐quality evidence to support the use of either loco‐regional or general anesthesia for endovascular aortic aneurysm repair (EVAR) due to the lack of eligible studies for inclusion in this review. Currently, randomized controlled trials are lacking in this area. There are several potential reasons. Loco‐regional anesthesia requires surgeons and anesthesiologists who are experienced in administering this anesthetic modality, and operating on a person who is non‐intubated and awake. This would make recruiting participants for a sufficiently powered trial challenging, and may explain why fewer people undergo loco‐regional anesthesia compared to general in existing observational studies. However, the increasing number of observational studies that show positive results may create a push for greater use of loco‐regional anesthesia for EVAR, which would make conducting a randomized controlled trial more feasible (Harky 2020; Karthikesalingam 2012).

Quality of the evidence

It was not possible to assess the certainty of the evidence due to the lack of eligible studies for inclusion in this review.

Potential biases in the review process

We carried out the search and evaluation of the studies in accordance with Cochrane guidelines (Higgins 2022). We were unable to identify any eligible randomized controlled trials for inclusion in the review.

Agreements and disagreements with other studies or reviews

This review did not identify any studies or reviews that analyzed data from randomized controlled trials to compare the effects of general versus loco‐regional anesthesia for endovascular aortic aneurysm repair. However, previous reviews have analyzed non‐randomized studies that compared general versus loco‐regional anesthesia for endovascular abdominal aortic aneurysm repair.

For elective EVAR, a meta‐analysis including 12 observational studies reported that loco‐regional anesthesia was at least equivalent to general anesthesia, and may offer certain advantages, including shorter operative times and hospital stays. Harky 2020 included 1664 participants in the loco‐regional group and 10,360 in the general anesthesia group. They found no clear difference in 30‐day mortality (2% loco‐regional versus 1.7% general; P = 0.97), and no clear difference in cardiac (2.7% versus 2.5%; P = 0.46), or renal (1.2% versus 1.6%; P = 0.13) complications. Shorter surgical time (135 ± 40 minutes versus 164 ± 43 minutes; P < 0.00001), and shorter hospital stay (3.6 ± 3.3 days versus 4.6 ± 5 days; P = 0.002) were also observed in the loco‐regional participants (Harky 2020).

A 2012 meta‐analysis, which included 10 prospective and retrospective studies with 13,459 participants, reported no clear difference in 30‐day mortality between local and general anesthesia (odds ratio (OR) 0.7, 95% confidence interval (CI) 0.39 to 1.26; P = 0.235), and found that people who received local anesthesia had shorter operative time (weighted mean difference (WMD) 0.54 minutes, 95% CI 0.87 to 0.22; P = 0.001), shorter hospital stay (WMD ‐0.27 days, 95% CI – 0.43 to – 0.1; P = 0.001), and fewer postoperative complications (OR 0.54, 95% CI 0.41 to 0.72, P < 0.001 (Karthikesalingam 2012)).

Similarly, a meta‐analysis of 15 observational studies with 15,472 participants found that loco‐regional anesthesia improved perioperative morbidity (OR 0.73, 95 % CI 0.55 to 0.96; P = 0.02) and mortality (OR 0.70, 95 % CI 0.52 to 0.95; P = 0.02), while also reporting shorter hospital stays with local (P = 0.003) and regional anesthesia (P < 0.0001) when compared to general anesthesia (Hajibandeh 2018).

For emergency EVAR, loco‐regional anesthesia was associated with improved mortality rates. In a 2018 systematic review, four studies (with 645 participants in the loco‐regional group and 2679 in the general group) demonstrated an overall mortality benefit for loco‐regional anesthesia in emergency EVAR (Armstrong 2018).

A 2021 meta‐analysis of 3116 participants (867 receiving loco‐regional and 2249 receiving general anesthesia) also found a mortality benefit for people receiving loco‐regional anesthesia while undergoing emergency EVAR (OR 0.47, 95% CI 0.32 to 0.68, P = 0.072 (Deng 2021)). Pulmonary complications (OR 0.76, 95% CI 0.42 to 1.38; P = 0.37), kidney complications (OR 0.75, 95% CI 0.35 to 1.60; P = 0.45), and intensive care unit admissions (OR 1.20, 95% CI 0.79 to 1.82; P = 0.39) were similar between groups.

Overall, these reviews reported that loco‐regional anesthesia is comparable to general anesthesia for mortality and postoperative complications. However, these findings are limited by a lack of randomization and the presence of clinical heterogeneity across the included studies, including non‐standardized anesthetic techniques, and a variety of factors that influenced anesthetic choice across sites. Moreover, sample sizes may have been underpowered to detect a difference between the groups, given the low number of complications and mortality events, and relatively few participants who received loco‐regional anesthesia compared to general anesthesia. Finally, important adjustment variables shown to be associated with postoperative mortality, such as the American Society of Anesthesiologists (ASA) status and preoperative hypotension, were not consistently applied across studies. These limitations highlight the need for high‐quality randomized trials in this area.

Authors' conclusions

Implications for practice.

We did not identify any randomized controlled trials that compared general versus loco‐regional anesthesia for endovascular aortic aneurysm repair. There is insufficient high‐quality evidence to determine the benefits and harms of either anesthetic approach during endovascular aortic aneurysm repair. Which particular anesthetic modality benefits which particular person for endovascular aortic aneurysm repair is still unclear, and continues to be determined by equipoise.

Currently, selection of anesthetic modality is largely based on physician preference, including individual biases and experience with loco‐regional anesthesia. There may also be person‐specific factors at play, including their medical risk, complexity of their procedure, and anatomy. General anesthesia may be more practical in some people undergoing endovascular aortic aneurysm repair, as it provides better blood pressure control, a secured airway, and an easier conversion to open repair (if required).

Implications for research.

There are currently no randomized controlled trials assessing the effects of general versus loco‐regional anesthesia for endovascular aortic aneurysm repair (EVAR). However, the large number of retrospective and prospective series that have examined this topic suggests that there may be sufficient equipoise to warrant future randomized controlled trials that examine this question, using more rigorous research methodology.

There are limitations in the existing literature due to the lack of randomization. There was little information provided on which factors influenced the decision to perform loco‐regional anesthesia or general anesthesia. Given the lack of guidelines and concrete evidence on anesthetic modality for EVAR, selecting an anesthetic modality is largely dependent on physician and local preferences, creating a high risk of confounding. Furthermore, the effect of loco‐regional anesthesia may be overestimated in some cases. Some studies categorized people requiring conversion from loco‐regional to general anesthesia during surgery as receiving general anesthesia. This may have caused people who were sicker, and who required conversion, to be allocated to the general anesthesia group. There is also a wide variability on how loco‐regional anesthesia can be performed, which may bias the results. For instance, the type and dosage of sedative used can impact postoperative outcomes. Overall, due to the lack of randomized trial data, a significant risk of confounding remains.

Future trials need to ensure person‐related factors are adequately balanced between groups, and are sufficiently powered. This may be challenging, given that fewer sites regularly practice loco‐regional anesthesia for EVAR compared to general anesthesia. Participants should be stratified according to aneurysm location (thoracic or abdominal) and procedure type (emergency or elective), as these factors can sway the outcomes. Important outcomes following EVAR, namely endoleak, would need to be captured, as there were few studies that had adequate follow‐up (i.e. up to one year) to evaluate this outcome. Self‐reported outcomes, such as patient satisfaction, postoperative pain, and a person's comfort levels during the procedure, will provide information on how well people tolerate loco‐regional anesthesia, and whether they would opt for it in the future. Finally, one of the main outcomes of existing studies was hospital length of stay, which should continue to be captured in future studies, as it has implications for cost.

Future updates to this review should consider inclusion of observational studies. As more observational studies are published in the future, the larger amount of data may help mitigate current issues with confounding and other limitations in the literature, as described above.

History

Protocol first published: Issue 11, 2018

Notes

Parts of the methods section of this review are based on a standard template established by Cochrane Vascular.

Appendices

Appendix 1. Sources searched and search strategies

Source	Search strategy	Hits retrieved
1. VASCULAR REGISTER IN CRSW (Date of most recent search 11 March 2022)	#1 AAA AND INREGISTER #2 Aortic Aneurysm AND INREGISTER #3 AORTA AND INREGISTER #4 Aneurysm AND INREGISTER #5 TAA AND INREGISTER #6 #1 OR #2 OR #3 OR #4 OR #5 #7 anaesth* AND INREGISTER #8 anesth* AND INREGISTER #9 #7 OR #8 #10 #6 AND #9	Dec 2018: 252 March 2022: 53
2. CENTRAL via CRSO (Date of most recent search 11 March 2022)	#1 MESH DESCRIPTOR Aortic Aneurysm EXPLODE ALL TREES #2 MESH DESCRIPTOR AORTA EXPLODE ALL TREES #3 MESH DESCRIPTOR Aneurysm, Ruptured EXPLODE ALL TREES #4 Aneurysm, Dissecting #5 (aneurysm* near4 (abdom* or thoracoabdom* or thoraco‐abdom* or aort*)):TI,AB,KY #6 AAA*:TI,AB,KY #7 TAA*:TI,AB,KY #8 (thoracic near3 (balloon* or dilat* or bulg*)):TI,AB,KY #9 (abdom* near3 (balloon* or dilat* or bulg*)):TI,AB,KY #10 #1 OR #2 OR #3 OR #4 OR #5 OR #6 OR #7 OR #8 OR #9 #11 MESH DESCRIPTOR Anesthetics, General EXPLODE ALL TREES #12 MESH DESCRIPTOR ANESTHESIA EXPLODE ALL TREES #13 MESH DESCRIPTOR Anesthesia, Local EXPLODE ALL TREES #14 (Anesthetics, Local):TI,AB,KY #15 an?esth*:TI,AB,KY #16 #11 OR #12 OR #13 OR #14 OR #15 #17 #10 AND #16	Dec 2018: 224 March 2022: 54
3. Clinicaltrials.gov (Date of most recent search 11 March 2022)	Anesthetic* OR Anesthesia OR Anaesthesia or Anaesthetic* | Aortic Aneurysm OR Aneurysm, Ruptured OR Aneurysm, Dissecting OR AAA OR TAA	Dec 2018: 61 March 2022: 60
4. ICTRP Search Portal (Date of most recent search 11 March 2022)	Anesthetic* OR Anesthesia OR Anaesthesia or Anaesthetic* | Aortic Aneurysm OR Aneurysm, Ruptured OR Aneurysm, Dissecting OR AAA OR TAA	Dec 2018: 147 March 2022: 4
5. MEDLINE (Ovid MEDLINE® Epub Ahead of Print, In‐Process & Other Non‐Indexed Citations, Ovid MEDLINE® Daily and Ovid MEDLINE®) 1946 to present (Date of most recent search 11 March 2022)	1 exp Aortic Aneurysm/ 2 exp AORTA/su [Surgery] 3 exp Aneurysm, Ruptured/su [Surgery] 4 exp Aneurysm, Dissecting/su [Surgery] 5 (aneurysm* adj4 (abdom* or thoracoabdom* or thoraco‐abdom* or aort*)).ti,ab. 6 AAA*.ti,ab. 7 TAA*.ti,ab. 8 (thoracic adj3 (balloon* or dilat* or bulg*)).ti,ab. 9 (abdom* adj3 (balloon* or dilat* or bulg*)).ti,ab. 10 or/1‐9 11 exp Anesthetics, General/ 12 exp ANESTHESIA/ 13 exp Anesthesia, Local/ 14 exp Anesthetics, Local/ 15 an?esth*.ti,ab. 16 or/11‐15 17 10 and 16 18 randomized controlled trial.pt. 19 controlled clinical trial.pt. 20 randomized.ab. 21 placebo.ab. 22 drug therapy.fs. 23 randomly.ab. 24 trial.ab. 25 groups.ab. 26 or/18‐25 27 exp animals/ not humans.sh. 28 26 not 27 29 17 and 28	Dec 2018: 38 March 2022: 98
6. Embase via OVID 1974 to present (Date of most recent search 11 March 2022)	1 exp aortic aneurysm/ 2 exp aorta/ 3 exp aneurysm rupture/su [Surgery] 4 exp dissecting aneurysm/su [Surgery] 5 (aneurysm* adj4 (abdom* or thoracoabdom* or thoraco‐abdom* or aort*)).ti,ab. 6 AAA*.ti,ab. 7 TAA*.ti,ab. 8 (thoracic adj3 (balloon* or dilat* or bulg*)).ti,ab. 9 (abdom* adj3 (balloon* or dilat* or bulg*)).ti,ab. 10 or/1‐9 11 exp anesthetic agent/ 12 exp anesthesia/ 13 exp local anesthesia/ 14 exp local anesthetic agent/ 15 an?esth*.ti,ab. 16 or/11‐15 17 10 and 16 18 randomized controlled trial/ 19 controlled clinical trial/ 20 random$.ti,ab. 21 randomization/ 22 intermethod comparison/ 23 placebo.ti,ab. 24 (compare or compared or comparison).ti. 25 ((evaluated or evaluate or evaluating or assessed or assess) and (compare or compared or comparing or comparison)).ab. 26 (open adj label).ti,ab. 27 ((double or single or doubly or singly) adj (blind or blinded or blindly)).ti,ab. 28 double blind procedure/ 29 parallel group$1.ti,ab. 30 (crossover or cross over).ti,ab. 31 ((assign$ or match or matched or allocation) adj5 (alternate or group$1 or intervention$1 or patient$1 or subject$1 or participant$1)).ti,ab. 32 (assigned or allocated).ti,ab. 33 (controlled adj7 (study or design or trial)).ti,ab. 34 (volunteer or volunteers).ti,ab. 35 trial.ti. 36 or/18‐35 37 17 and 36	Dec 2018: 184 March 2022: 452
7. CINAHL via EBSCO (Date of most recent search 11 March 2022)	S32 S16 AND S31 S31 S17 OR S18 OR S19 OR S20 OR S21 OR S22 OR S23 OR S24 OR S25 OR S26 OR S27 OR S28 OR S29 OR S30 S30 MH "Random Assignment" S29 MH "Triple‐Blind Studies" S28 MH "Double‐Blind Studies" S27 MH "Single‐Blind Studies" S26 MH "Crossover Design" S25 MH "Factorial Design" S24 MH "Placebos" S23 MH "Clinical Trials" S22 TX "multi‐centre study" OR "multi‐center study" OR "multicentre study" OR "multicenter study" OR "multi‐site study" S21 TX crossover OR "cross‐over" S20 AB placebo* S19 TX random* S18 TX trial* S17 TX "latin square" S16 S9 AND S15 S15 S10 OR S11 OR S12 OR S13 OR S14 S14 TX an?esth* S13 (MH "Anesthetics, Local+") S12 (MH "Anesthesia, Local") S11 (MH "Anesthesia+") S10 (MH "Anesthetics, General+") S9 S1 OR S2 OR S3 OR S4 OR S5 OR S6 OR S7 OR S8 S8 TX abdom* N3 (balloon* or dilat* or bulg*) S7 TX thoracic N3 (balloon* or dilat* or bulg*) S6 TX TAA* S5 TX AAA* S4 TX aneurysm* N4 (abdom* or thoracoabdom* or thoraco‐abdom* or aort*) S3 (MH "Aneurysm, Dissecting+/SU") S2 (MH "Aorta+/SU") S1 (MH "Aortic Aneurysm+")	Dec 2018: 166 March 2022:
TOTAL before de‐duplication		Dec 2018: 1072 March 2022: 765
TOTAL after de‐duplication		Dec 2018: 893 March 2022: 672

Differences between protocol and review

There were no differences between the protocol and the review.

Contributions of authors

SL: study selection, data extraction and analysis, analysis interpretation, and drafting of final review, updating the review
CY: study selection, data extraction and analysis, analysis interpretation, and drafting of final review, updating the review
AK (Andrew Kucey): drafting the proposal and protocol, analysis interpretation, and drafting of final review
FA: drafting the proposal and protocol, analysis interpretation, and drafting of final review
GP: drafting the proposal and protocol, analysis interpretation, and drafting of final review
DK: drafting the proposal and protocol, analysis interpretation, and drafting of final review
TF: drafting the proposal and protocol, analysis interpretation,, and drafting of final review
SC: drafting the proposal and protocol, analysis interpretation and drafting of final review
AD: drafting the proposal and protocol, analysis interpretation, and drafting of final review, updating the review
AK (Ahmed Kayssi): drafting the proposal and protocol, analysis interpretation, and drafting of final review, updating the review

Sources of support

Internal sources

• none to declare, Other

  none

External sources

• Chief Scientist Office, Scottish Government Health Directorates, The Scottish Government, UK

  The Cochrane Vascular editorial base is supported by the Chief Scientist Office.

Declarations of interest

SL: none known 
CY: none known 
AK: none known
FA: none known. FA declared that he works as a health professional at Sunnybrook Health Sciences Centre
GP: none known. GP declared that he works as a health professional at Sunnybrook Health Sciences Centre
DK: none known. DK declared that he works as a health professional at University of Toronto
TF: none known. TF declared that he is EIC for the Journal of Vascular Surgery and works as a health professional (Vascular Surgeon at University Health Network, Toronto)
SC: none known.  SC declared that he works as a health professional at Sunnybrook Health Sciences Centre. He routinely provides anesthetic care for this type of procedure
AD: none known. AD declared he works as a vascular surgeon at Sunnyboook Hospital
AK: none known. AK declared he works as a vascular surgeon and wound care physician

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