Interact CardioVasc Thorac Surg 2009;8:35-39. doi:10.1510/icvts.2008.190165
© 2009 European Association of Cardio-Thoracic Surgery
Institutional report - Aortic and aneurysmal |
The retroperitoneal approach combined with epidural anesthesia reduces morbidity in elective infrarenal aortic aneurysm repair
Bernd M. Muehlinga,*,
Rainer Meierhenrichb,
Matthias Thierea,
Gisela Bischoffa,
Alexander Oberhubera,
Karl Heinz Orenda and
Ludger Sunder-Plassmanna
a Department of Thoracic and Vascular Surgery, University of Ulm, Steinhövelstrasse 9, 89075 Ulm, Germany
b Department of Anesthesiology and Intensive Care Medicine, University of Ulm, Germany
Received 10 August 2008;
received in revised form 8 September 2008;
accepted 9 September 2008
*Corresponding author. Tel.: +49-731-500-54044; fax: +49-731-500-26705.
E-mail address: bernd.muehling{at}uniklinik-ulm.de (B.M. Muehling).
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Abstract
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In elective open infrarenal aortic aneurysm repair the surgical approach and the use of epidural anesthesia (EDA) may determine patients' outcome. Hence we analyzed our results after elective open aneurysm repair in the light of the surgical approach and the use of EDA. Retrospective analysis of a prospective data base. From December 2005 to April 2008, 125 patients with infrarenal aortic aneurysm underwent elective open repair. Patients were divided into four groups: retro- and transperitoneal approach with and without epidural anesthesia (RP±EDA and TP±EDA). In terms of age, sex, aneurysm diameter, ASA score and clamping time all groups were comparable. In the retroperitoneal groups significantly more tube grafts were implanted (63 vs. 27; P=0.001). The rate of surgical complications did not differ between the groups. The RP+EDA group had the lowest rate of postoperative assisted mechanical ventilation (5.1% vs. 35.7%; P=0.002) and medical complications (17.9% vs. 42.8%; P=0.032). Concerning frequency of surgical complications, the retroperitoneal incision was comparable to the transperitoneal approach in infrarenal aortic reconstruction. Supplementation with EDA resulted in a decreased rate of postoperative assisted mechanical ventilation and in lower morbidity rates.
Key Words: Retroperitoneal approach; Aortic aneurysm; Epidural anesthesia
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1. Introduction
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In elective infrarenal aortic aneurysm repair the standard approach is the transperitoneal via a midline incision. Due to reduced morbidity and hospital cost the retroperitoneal approach is favored by some authors but prospective randomized trials revealed contradictory results [1, 2]. The retroperitoneal approach offers advantages in patients with hostile abdomen and horseshoe kidney but has disadvantages if aneurysmal disease of the iliac arteries is present [3]. Most vascular surgeons prefer the transperitoneal approach as standard. However, morbidity of elective infrarenal aortic aneurysm repair not only depends on the surgical approach but on perioperative management. Over the past decade the peri- and intraoperative care of patients undergoing aortic aneurysm repair has continously improved by means of preoperative identification of concomitant coronary heart and cerebrovascular disease, introduction of Swan–Ganz catheter, intraoperative transesophageal echo- cardiography and advances in intensive care medicine. Nevertheless, infrarenal aortic reconstruction is accompanied by mortality rates of approximately 5% and morbidity rates of approximately 35% [4]. Therefore some authors feel the treatment of patients with abdominal aortic aneurysm has not improved over the last 20 years [5]. Implementing an optimized perioperative patient care (fast track) regimen we had encouraging results in terms of perioperative morbidity in a prospective randomized trial of elective open aortic aneurysm repair [6]. A cornerstone in this concept is the use of regional anesthetic techniques, i.e. epidural anesthesia, in order to reduce surgical stress and optimize postoperative pain management [7]. As aortic reconstruction represents a complex surgical procedure it remains questionable if morbidity is solely dependent on the surgical approach. Taken that the complex pathophysiological changes during aortic reconstruction are multifactorial, any attempt to influence the outcome has also to be multifactorial. To elucidate the role of retroperitoneal approach (RP) in combination with epidural anesthesia (EDA) we analyzed our elective aortic reconstructions depending on the surgical approach and the use of epidural anesthesia.
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2. Materials and methods
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2.1. Data analysis
We retrospectively analyzed a prospective data base of elective infrarenal aortic aneurysm repairs that were performed at the department of Thoracic and Vascular Surgery at the University Hospital Ulm between December 2005 and February 2008. During that time, 125 patients underwent elective open repair of an infrarenal aortic aneurysm. Patients with thoracoabdominal, juxtarenal aneurysms and endovascular repair were excluded from the analysis. For our investigation patients were divided into four groups according to the surgical approach and the use of epidural anesthesia (EDA): retroperitoneal (RP) ±EDA and transperitoneal (TP) ±EDA. Each group was compared for demographic data: age, sex, aneurysm diameter, ASA classification, clamping time, preoperative hemoglobin and baseline creatinine. Outcome measurements were in hospital mortality, need for assisted mechanical ventilation (AMV), length of stay (LOS) on intensive care unit (ICU), day of discharge and surgical and medical complications during the postoperative course according to the defined variables (Table 2).
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Table 2 Definition of variables: If two or more criteria in each category were documented the medical complication was confirmed
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2.2. Statistical analysis
For discrete variables absolute and relative frequencies are given. For continuous frequencies median values and range are applied. To calculate significance of morbidity/mortality and postoperative complications in the treatment groups Fisher's exact test was used. P-values <0.05 were regarded to be significant. To calculate significance concerning duration of ICU treatment and day of discharge, two-sided Wilcoxon–Mann–Whitney-test was applied. Statistical analysis was performed in collaboration with the Department of Biometry using the computer program SigmaStat.
2.3. Perioperative management
Patients admitted for elective infrarenal aortic reconstruction are first seen in our outpatients department. Cardiovascular risk adjustment is performed by the anesthesiologists. The patients' regular medication – in particular β-blockers – is continued perioperatively. All patients receive an oral benzodiazepine premedication with clorazepate dipotassium (20 mg) in the evening and midazolam (7.5 mg) one hour prior to induction of anesthesia. If no contraindications (e.g. coagulopathy) are present patients are randomly supplemented with EDA, which is inserted preoperatively in the intervertebral spaces at the level between T7-10 with the loss-of-resistance technique and removed if pain control can be achieved by i.v. medication alone, usually after 2–3 days. After induction of general anesthesia, a bladder catheter is inserted which is removed as soon as patients are mobilized (1–2 days after surgery). All surgical procedures are performed under a single shot antibiotic therapy with cefuroxime (1.5 g). Intraoperative fluid administration (crystalloids, colloids) is adjusted to blood loss and cardiovascular parameters (heart rate, blood pressure) without preassigned restriction. All patients are extubated immediately after surgery if they fulfill the following criteria: core temperature >36 °C, hemodynamic stability without need for catecholamine therapy and exclusion of residual paralysis. In our department patients after elective open aneurysm repair are routinely transferred to the ICU, where they are observed overnight and transferred to the surgical floor on postoperative day (POD) #1 if they fulfill the following criteria: stable hemodynamic parameters, no clinical signs of organ failure and stable laboratory tests (e.g. hemoglobin).
2.4. Surgical technique
The transperitoneal approach to the infrarenal aorta is achieved via a midline incision; in patients with concomitant iliac aneurysms we prefer the transperitoneal approach. In the case of retroperitoneal incision we use a curvilinear incision starting at the tip of the 11th rib without routine resection of the rib and continuing obliquely to a point midway above the os pubis (Figs. 1–2 ). After dissecting the oblique muscles we use a posterolateral approach to the aorta as supposed by Willliams et al. [8]. The retroperitoneal approach is preferred in case of hostile abdomen, horseshoe kidney or in case of an anatomically complex neck which may require suprarenal clamping. All grafts used were made of Dacron and either tube of bifurcated grafts depending on the presence or absence of iliac aneurysms.
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Fig. 1. Positioning for the retroperitoneal approach; the patient is positioned in 45° elevation of the left hip and left shoulder; the incision is made from the tip of the 11th rib to a point midway above the os pubis.
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Fig. 2. Intraoperative situs: The center of the picture shows the aortic aneurysm (AAA), the aortic neck being on the right, the common iliac arteries on the left (LCIA: left common iliac artery); the M. iliopsoas serves a landmark for the retroperitoneal route.
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2.5. Demographic data
Table 1 gives an overview over demographic data of the analyzed patients. Concerning age, sex, aneurysm diameter, ASA classification, preoperative hemoglobin, baseline creatinine, clamping time and total operating time, there were no significant differences. As for implanted grafts there were significantly more tube grafts implanted in the retroperitoneal groups (63 vs. 27, P=0.001).
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Table 1 Demographic data of the four groups; there was significant difference concerning the used grafts: in the retroperitoneal groups significantly more tube grafts were implanted
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2.6. Definition of variables
Organ failure during the postoperative course was documented according to the definition of variables depicted in Table 2. If two or more criteria in each category were documented the medical complication was confirmed.
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3. Results
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3.1. Assisted mechanical ventilation, ICU, blood units transfused, day of discharge
The postoperative outcome in terms of need for AMV, ICU treatment, blood units transfused and day of discharge are given in Table 3; the need for postoperative assisted mechanical ventilation was significantly decreased in the RP+EDA group as compared to the TP–EDA group (5.1% vs. 35.7%, P=0.003). The transfusion of banked blood ranged from 0–8 units without any significant differences between the groups. Duration of ICU treatment showed a tendency to shorter stay in the RP groups and the TP+EDA group compared to the TP–EDA patients. Median day of discharge ranged from 9 to 11 days in all groups. In-hospital no patient died during our observation period.
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Table 3 Perioperative outcome in terms of need for assisted mechanical ventilation (AMV), length of stay on ICU and day of discharge
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3.2. Surgical complications
Detailed overview over surgical complications and frequency of re-operation is given in Table 4. Surgical complications were peripheral ischemia with the need for embolectomy in three patients in the RP+EDA and one patient in the RP–EDA and TP+EDA group. In the RP+EDA we observed one patient with ischemic colitis that required resection of the left hemicolon and one patient each with spleen rupture and lesion of the ureter. Other surgical complications included graft occlusion, ileus requiring a stoma and incisional hernia in the transperitoneal group; in summary the frequency of re-operation between the groups did not differ.
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Table 4 Overview over surgical complications according to approach and use of epidural anesthesia. There is no significant difference between the groups according to surgical approach and use of EDA
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3.3. Medical complications
Medical complications according to the defined variables were documented during the postoperative course as follows (Table 5): Cardio-pulmonary complications occurred in three, two, two and four patients in the groups; acute renal failure (ARF) was documented in two, four, three and one patient; one patient with ARF in the RP-EDA group required postoperative dialysis; as for gastrointestinal complications we had the highest rate of subileus in the TP-EDA group (7 patients). Altogether the RP+EDA group had the lowest rate of medical complications which was significant as compared to the TP–EDA group (17.9% vs. 42.8%, P=0.032); comparison of the EDA groups to non-EDA groups irrespective of the surgical approach revealed a significant advantage for EDA groups (19.4% vs. 39.6%, P=0.022).
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Table 5 Overview over medical complications according to approach and use of epidural anesthesia. Compared to transperitoneal approach without epidural anesthesia the retroperitoneal approach combined with EDA shows significant less medical complications; comparing the groups according to the use of epidural anesthesia the RP and TP groups supplemented with EDA show significant less medical complications
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4. Discussion
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In elective infrarenal aortic aneurysm repair the optimal surgical approach is still an issue of controversaries. There are prospective randomized trials that could show an advantage for the retroperitoneal incision in terms of postoperative complications as well as trials that failed to demonstrate superiority of one or the other [1, 2]. Several studies have claimed physiological advantages of the RP approach over the TP approach which may be attributed to mesenteric traction and intestinal manipulation [9]. However, aortic reconstruction with cross-clamping and ischemia-reperfusion injury is an operation with complex pathophysiological changes on blood flow and metabolism in dependent organs [10]. Hence it is unlikely that reduction of morbidity is solely dependent on the surgical approach. At our institution we have implemented a fast track clinical pathway to reduce morbidity and mortality after elective infrarenal aortic reconstruction [6]. A cornerstone in this concept is the use of EDA which has been shown to have beneficial effects on patients outcome after cardiac surgery [11]. Since 2005 we prospectively collected data of all patients undergoing elective infrarenal aortic aneurysm repair. This database, comprising actually 125 patients, was reviewed for morbidity and mortality rates according to the surgical approach and the use of epidural anesthesia. We prefer the retroperitoneal approach in patients who are obese or have a hostile abdomen or in patients with an anatomically complex neck; these conditions are widely accepted for the retroperitoneal approach and have been described by others [12]. Another condition which may favor the RP incision is presence of a horseshoe kidney which was the case in two patients in our series. Dividing our patients into four groups (RP±EDA and TP±EDA) revealed clear advantages for the RP group supplemented with EDA: in this group we had the lowest morbidity rate with 17.9% which was significant as compared to the other groups. Moreover, the need for postoperative mechanical ventilation is significantly reduced using retroperitoneal approach supplemented with EDA compared to TP-EDA (5.1% vs. 35.7%, P=0.003). These findings are in line with the results of other investigators where the use of regional anesthetic techniques in major surgery showed beneficial effects in terms of postoperative pain relief, duration of tracheal intubation and overall morbidity [13]. The length of stay on ICU was not significantly different between the groups ranging from 20 to 33.5 h median. Specialized centers report about duration of ICU treatment up to 6 days [14].
As for surgical complications there was no significant difference between the groups. Specific complications in the retroperitoneal groups were spleen rupture and the ureter lesion, complications that have been reported by others as well [12, 15]. In summary, the rate of re-operations according to the approach was 11% in the RP and 9% in the TP patients (n.s.).
Mortality rates in elective open infrarenal aortic aneurysm are approximately 5% [4]; in our series we fortunately observed no deaths in-hospital which may be due to the relatively small number and the fact that high-risk patients, i.e. patients of advanced age >80 years and severe COPD (FEV1 <1.5 l) are either considered for endovascular repair or a watch and wait strategy.
As for medical complications, the retroperitoneal group supplemented with EDA showed the lowest rate with 17.9% which was significant as compared to the other groups. Comparing EDA groups to non-EDA groups irrespective of the surgical approach, we found a significant difference in the overall complication rate (19.4% vs. 39.6%, P<0.022). We recognize the relatively small number in each group, however, our results are in line with the results of other investigators who favor the retroperitoneal approach and the use of EDA in aortic reconstructive surgery to reduce morbidity [13]; a complication of epidural anesthesia may be bleeding resulting in paralysis, which fortunately did not occur in our series; the retroperitoneal approach offers the above-mentioned technical advantages but is in our opinion not the only factor that determines outcome after elective infrarenal aortic aneurysm repair, which represents a complex surgical procedure. With the advance of anesthetic techniques – especially EDA – these should be part of the armamentarium in the treatment and perioperative management of patients with abdominal aortic aneurysm and should be routinely used. However, further evidence is warranted to justify routine implementation of EDA in combination with the retroperitoneal approach in elective open repair of infrarenal aortic aneurysms.
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Abstract
1. Introduction