Annals of Vascular Surgery
Volume 24, Issue 6 , Pages 728-732, August 2010

Retroperitoneal Repair of Abdominal Aortic Aneurysms Offers Postoperative Benefits to Male Patients in the Veterans Affairs Health System

Department of Surgery, Tennessee Valley Healthcare System, Nashville Campus, Nashville, TN

published online 14 May 2010.

Article Outline

Background

Transperitoneal (TP) and retroperitoneal (RP) approaches have equal efficacy in elective open abdominal aortic aneurysm (AAA) repair. The effect of open operative approach on patient-specific outcomes after AAA repair was tested.

Methods

Consecutive patients undergoing open AAA repair at the Veterans Affairs Tennessee Valley Healthcare System between January 2000 and August 2008 were retrospectively reviewed. Analysis was performed to examine the effects of demographic and clinical covariates on postoperative outcomes.

Results

A total of 106 patients were identified: 54 with TP approach and 52 with RP approach. Demographics and preoperative comorbidities were equivalent (p ≥ 0.10), with the exception of chronic obstructive pulmonary disease which was more prevalent in the TP group (61 vs. 40%). Operative times were longer in the TP group (4.6 vs. 3.5 hours; p < 0.01); however, significantly more TP patients had reconstruction with a bifurcated graft (72 vs. 2%; p < 0.01). Postoperative nasogastric tube decompression times were shorter in the RP group (1 vs. 3 days; p < 0.01), and RP approach led to a quicker return to preoperative diet (4 vs. 6 days; p = 0.05). Patients undergoing RP repair developed fewer incisional hernias (2 vs. 15%; p = 0.03).

Conclusion

RP approach to AAA repair offers patients faster return of bowel function and is associated with fewer incisional hernias.

 

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Introduction 

The surgical management of abdominal aortic aneurysms (AAAs) has evolved significantly over the past 18 years since the advent of endovascular aortic repair (EVAR); however, EVAR is not practical for younger patients as well as those with certain anatomical configurations.1, 2 Furthermore, patient interest in open repair of AAAs continues among those who are not interested in long-term follow-up surveillance after EVAR. Therefore, it is imperative that at the present time vascular surgeons be able to confidently perform open repair as well as EVAR.

The specific approach used for open repair has been an area of extensive research over the past 30 years. There is still not a consensus as to whether the transperitoneal (TP) or retroperitoneal (RP) approach offers better patient outcomes. Most authors agree that the RP approach is superior to the TP approach for patients with supra- and juxtarenal AAAs, renal ectopia, obesity, inflammatory aneurysms, previous abdominal or aortic surgery, and high surgical risk.3, 4, 5, 6, 7, 8, 9 Many studies have suggested that the RP approach is associated with a decrease in intensive care unit (ICU) length of stay (LOS) and total hospital LOS, an earlier return of bowel function, a reduction in pulmonary complications, and, ultimately, a decrease in overall cost.3, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 A few of these authors suggest that the RP exposure should be the standard surgical approach to elective AAA repair.10, 13, 19, 21

Alternatively, studies have demonstrated a higher incidence of wound complications with the RP repair, and one prospective randomized trial failed to show any convincing advantage to using the RP approach over the TP approach.22, 23 We wished to review our experience with RP and TP approaches to AAA repair and to investigate whether the technique of operative exposure altered patient-specific outcomes after AAA repair.

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Materials and Methods 

Patients and Measures 

All patients underwent elective open AAA repair at the Veterans Affairs Tennessee Valley Healthcare System, Nashville Campus, between January 2000 and August 2008. All patients with aortoiliac disease and those requiring groin dissections for a successful reconstruction were excluded from the study. The study cohort was subsequently stratified into two groups: RP and TP approach to AAA repair.

Patient demographic and clinical data were collected using the Computerized Patient Record System. Demographic variables used were age, gender, race, and body mass index. Preoperative health measures included smoking status, American Society of Anesthesiologists Class, cardiac ejection fraction (EF), and aneurysm size. Preoperative comorbidities included hypertension, diabetes mellitus, chronic renal insufficiency (stratified by Cr >1.5), prior cerebrovascular accident, prior myocardial infarction, coronary artery disease, chronic obstructive pulmonary disease (COPD; stratified based on forced expiratory volume [FEV1] <75%), and prior cardiac intervention.

Operative data included in the study were operative time, graft use (tube or bifurcated), estimated blood loss (in milliliters), cell-saver use (in milliliters), transfusion requirement (measured in units of packed red blood cells administered), crystalloid resuscitation (in milliliters), and epidural use. Postoperative data assessed ICU LOS ward LOS, total hospital LOS, ventilator duration, pneumonia rate, re-intubation rate, cardiac complications (ischemia and/or arrhythmia), acute renal failure (ARF), nasogastric tube (NGT) duration, return to preoperative diet, wound infection, wound hematoma, wound hernia, and mortality.

Operative Technique 

A standard midline incision was used for all TP approaches to the AAA repair. After intra-abdominal examination, the aorta was exposed inferior to the transverse mesocolon, and the bowel was retracted and held in place with a self-retaining retractor.

All RP approaches to the AAA repair were performed using an incision off the tip of the left eleventh rib brought medially to the lateral border of the left rectus sheath. The rectus abdominus muscle was not divided, but the tip of the eleventh rib was resected in the majority of cases to provide improved exposure and isolation of the associated neurovascular bundle. The peritoneum was swept anteromedially along with the left kidney and associated vessels. The left renolumbar vein was ligated to facilitate proper and adequate exposure of the aorta.

Analysis 

Univariate analyses examined the differences in demographic and clinical covariates between the RP and TP groups. Continuous data were tested with the Student's t test or Wilcoxon rank-sum test, depending on data skewness. Between group comparisons among the categorical variables were performed with Fisher's exact test or chi-square test, as appropriate. Summary data are reported as mean ± standard deviation (SD), median with interquartile range (IQR), or percentages. STATA 10.1 (Stata Corp., College Station, TX) statistical software was used for data management and analysis.

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Results 

The complete study cohort included 106 patients (TP = 54 and RP = 52) who underwent open AAA repair between January 2000 and August 2008. All patients were male. Patient demographics and preoperative health measures are summarized in Table I. There were no differences in age, race, body mass index, smoking status, cardiac EF, and American Society of Anesthesiologists Class (all p values ≥ 0.10). Patients undergoing TP exposure for AAA repair had slightly larger aneurysm size (6.7 ± 1.6 cm vs. 6.1 ± 1.1 cm, p = 0.05). Preoperative comorbidities were also equivalent between the two groups (all p values ≥0.36), with the exception of COPD which was more prevalent in the TP group (61 vs. 40%; p = 0.03; Table II). Intraoperative data are summarized in Table III. Operative time was significantly longer in the TP group (4.6 vs. 3.5 hours; p < 0.01); however, 98% of the patients were reconstructed with a tube graft after RP approach, whereas tube graft was used in only 28% of TP repairs (p < 0.01). Estimated blood loss and resuscitative measures did not differ between the two groups (all p values ≥0.10). Epidural use was more common in patients undergoing RP exposure (83 vs. 57%, p = 0.01).

Table I. Patient demographics and health measures
Transperitoneal
(n = 54)		Retroperitoneal
(n = 52)		p
Agea67 ± 869 ± 80.28
Caucasianb48 (89)51 (98)0.11
BMI (kg/m2)a27 ± 528 ± 60.54
Current smokersb42 (78)33 (63)0.10
Aneurysm size (cm)a6.7 ± 1.66.1 ± 1.10.05
Cardiac EF (%)a54 ± 957 ± 90.11
ASA classc3 (3-4)3 (3-4)0.53

aReported as mean ± SD.

bReported as number (percent).

cReported as median (IQR). BMI (body mass index); EF (ejection fraction); ASA (American Society of Anesthesiologists).

Table II. Preoperative comorbidities
Transperitoneal
(n = 54)		Retroperitoneal
(n = 52)		p
Hypertension47 (87)47 (90)0.76
Diabetes mellitus11 (20)11 (21)0.92
Chronic renal insufficiency8 (15)8 (15)0.94
Cerebrovascular accident6 (11)9 (17)0.36
Myocardial infarction16 (30)12 (23)0.44
Coronary artery disease25 (46)20 (38)0.42
COPD33 (61)21 (40)0.03
Prior cardiac intervention14 (26)11 (21)0.82

All values reported as number (percent), COPD (chronic obstructive pulmonary disease).

Table III. Intraoperative data
Transperitoneal
(n = 54)		Retroperitoneal
(n = 52)		p
Operative time (h)a4.6 ± 1.33.5 ± 1.0<0.01
Tube graftb15 (28)51 (98)<0.01
Estimated blood loss (mL)c1,500 (500-4,500)1,500 (500-5,200)0.38
Cell-saver (mL)c800 (0-1,800)973 (0-2,500)0.26
Transfusion (units)c1 (0-5)2 (0-5)0.10
Crystalloid (mL)a6.3 ± 2.65.8 ± 2.50.38
Epiduralb31 (57)43 (83)0.01

aReported as mean ± SD.

bReported as number (percent).

cReported as median (IQR).

The postoperative data are summarized in Table IV. Patients undergoing RP approach had significantly shorter median duration of NGT decompression (1 vs. 3 days, p < 0.01). Similarly, the RP approach resulted in a significantly quicker return to preoperative diet (4 vs. 6 days, p = 0.05). In addition, patients undergoing the RP repair developed significantly fewer incisional hernias (2 vs. 15%, p = 0.03). There were no significant differences between any of the LOS metrics (all p values >0.34). The median total hospital LOS was 7 days for both groups (p = 0.95). Ventilatory duration, re-intubations, development of pneumonia, cardiac complications, acute renal failure, wound infections, and wound hematomas were not significantly different between the groups (all p values ≥0.14). There were no episodes of ischemic colitis in either group. The 30-day mortality did not differ between the two patient groups (p = 0.74).

Table IV. Postoperative data and outcomes
Transperitoneal
(n = 54)		Retroperitoneal
(n = 52)		p
ICU length of stay (d)a3 (1-17)3 (1-9)0.36
Ward length of stay (d)a4 (1-13)4 (2-11)0.34
Total length of stay (d)a7 (4-33)7 (5-19)0.95
Nasogastric tube (d)a2 (1-11)1 (1-3)<0.01
Return to diet (d)a4 (3-20)4 (2-8)0.05
Ventilator (d)a1 (1-9)1 (1-4)0.14
Re-intubationb8 (15)6 (12)0.62
Pneumoniab8 (15)3 (6)0.20
Cardiac complicationsb8 (15)4 (8)0.36
Wound infectionb3 (6)7 (13)0.20
Wound hematomab0 (0)1 (2)0.49
Herniab8 (15)1 (2)0.03
Renal failureb6 (11)4 (8)0.74
Mortalityb1 (2)1 (2)1.00

aReported as median (IQR).

bReported as number (percent).

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Discussion 

In 1951, Charles Dubost was the first to perform AAA excision with graft placement using a left thoracoabdominal approach, and it was in 1963 when Charles Rob published his 13-year experience of more than 500 RP aortic repairs so that the technique and its potential benefits were brought to the attention of the surgical community.24, 25 Most authors agree that the RP approach should be used for particular circumstances. Yet, this approach has not been widely adopted by all vascular surgeons and, therefore, remains an area of controversy.

The two approaches have similar operative mortality and long-term durability; however, the RP exposure has been shown to result in some specific improvements in postoperative patient outcomes.3, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 Although Cambria et al. did not demonstrate an overall difference between RP and TP approaches to AAA repair, their study did note an earlier return of gastrointestinal function in the RP group.23 Our data corroborate the results of this study and others, demonstrating that the RP approach results in an earlier return of gastrointestinal function.16, 17, 19, 26, 27 Regarding operative times, previous studies have conflicting results.3, 12, 18, 26 In agreement with Johnson et al. and Peck et al., our study demonstrated that the RP approach was associated with a shorter operative time in comparison with the TP approach.14, 15 This longer operative time, however, may be attributed to the greater use of bifurcated grafts with the TP repair.

The patients in our TP group had a higher incidence of postoperative hernia development, which contradicts previously published results from Sieunarine et al., who demonstrated a higher trend of hernias after RP exposure.22 Yet, the 15% incisional hernia rate in the TP group coincides with the previously reported 10% to 31% rates in patients with aneurysmal disease.28, 29, 30 Only one patient in our RP group developed an incisional hernia. The differences in hernia development could be a result of operative technique for RP exposure. Careful dissection of the 11th rib with preservation of the neurovascular bundle is required for prevention of postoperative flank bulging.

RP approach has also been associated with a reduction in pulmonary complications and LOS.3, 5, 11, 12, 20, 21, 31 Furthermore, Sicard et al. and Darling et al. demonstrated a significantly higher volume of intraoperative blood and crystalloid requirements with the TP approach.26, 31 Our results did not show significant differences in blood loss, transfusion and crystalloid requirements, pulmonary complications (ventilator days, pneumonia, or re-intubation), or LOS (in ICU or in ward). In addition, no difference in the rate of postoperative ARF or cardiac complications was observed. Of the 10 patients in the entire study cohort who developed ARF, two required temporary dialysis, whereas in the remaining eight (five of who had preoperative chronic renal insufficiency) renal function returned to preoperative baseline before hospital discharge.

This study has a number of limitations. It is retrospective and has a relatively small sample size, increasing the possibility of Type II error. Although many prospective studies have compared postoperative patient outcomes among the TP and RP approaches to the abdominal aorta, the results of these studies have been contradictory. Our study patients are different from the general population undergoing open AAA repair. The Veterans Affairs cohort was all male and had combined higher rates of hypertension, COPD, and chronic renal insufficiency. As such, our findings still suggest equivalence in most intra- and postoperative patient outcomes, with significantly improved return of bowel function and decreased frequency of hernia development in patients with RP exposure of AAA. Although we did not specifically determine the range of follow-up for the two groups, this could have influenced the incidence of true hernias versus bulges. The longer operative time with the TP group may be attributed to the use of bifurcated grafts. We acknowledge that there was selection bias in our study population secondary to the higher percentage of tube grafts in the RP group (98%) versus the TP group (28%).

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Conclusion 

Despite the increasing use of EVAR, it is still necessary for vascular surgeons to perform open repair of AAAs. Although familiarization with both techniques is important, the RP approach offers a shorter operative time, earlier return of gastrointestinal function, and fewer incisional hernias, when compared with the TP approach in patients undergoing elective open AAA repair.

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References 

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PII: S0890-5096(10)00095-6

doi:10.1016/j.avsg.2010.02.026

Annals of Vascular Surgery
Volume 24, Issue 6 , Pages 728-732, August 2010

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