Annals of Vascular Surgery
Volume 22, Issue 1 , Pages 25-29, January 2008

Improved Outcome after Rupture of Abdominal Aortic Aneurysm over an 18-Year Period

  • Łukasz Dzieciuchowicz

      Affiliations

    • Department of General and Vascular Surgery, Poznan University of Medical Sciences, Poznan, Poland
    • Corresponding Author InformationCorrespondence to: Lukasz Dzieciuchowicz, MD, PhD, State Clinical Hospital nr 1, Department of General and Vascular Surgery, Dluga ½, 61-848 Poznan, Poland
    • ,
  • Wacław Majewski

      Affiliations

    • Department of General and Vascular Surgery, Poznan University of Medical Sciences, Poznan, Poland
    • ,
  • Maciej Słowiński

      Affiliations

    • Department of General and Vascular Surgery, Poznan University of Medical Sciences, Poznan, Poland
    • ,
  • Zbigniew Krasiński

      Affiliations

    • Department of General and Vascular Surgery, Poznan University of Medical Sciences, Poznan, Poland
    • ,
  • Andrzej A. Jawien

      Affiliations

    • Department of General and Vascular Surgery, Poznan University of Medical Sciences, Poznan, Poland
    • ,
  • Krzysztof Bieda

      Affiliations

    • Department of Anesthesiology and Intensive Therapy, Poznan University of Medical Sciences, Poznan, Poland
    • ,
  • Grzegorz Oszkinis

      Affiliations

    • Department of General and Vascular Surgery, Poznan University of Medical Sciences, Poznan, Poland
    • ,
  • Marcin Gabriel

      Affiliations

    • Department of General and Vascular Surgery, Poznan University of Medical Sciences, Poznan, Poland
    • ,
  • Stanisław Zapalski

      Affiliations

    • Department of General and Vascular Surgery, Poznan University of Medical Sciences, Poznan, Poland

published online 04 December 2007.

Article Outline

The purpose of the study was to analyze changes in in-hospital mortality of patients with ruptured abdominal aortic aneurysm (RAAA) during an 18-year period. A retrospective analysis of 246 patients with RAAA in the years 1987-2005 was performed. The patients were divided into groups that consisted of 111 patients treated in the years 1987-2000 (group I) and 135 patients treated in the years 2001-2005 (group II). The in-hospital mortality rates of all patients and of operated patients in both groups were analyzed. Preoperative variables such as age, gender, size of the aneurysm, duration of symptoms, distance to the vascular surgery department, full blood count, serum creatinine and urea concentrations, and systolic and diastolic blood pressures, as well as the number of all AAAs and RAAAs treated per year, were compared between the groups. The Mann-Whitney U-test and Fisher exact test were used to analyze differences in continuous and categorical variables, respectively. The in-hospital mortality of all patients was significantly lower in group II (p = 0.006) The difference in in-hospital mortality of operated patients was of borderline statistical significance (p = 0.07). The proportion of nonoperated patients decreased from 21% to 6% (p = 0.0008). The patients from group II had significantly higher preoperative levels of hemoglobin, hematocrit, erythrocytes, and platelets, as well as higher systolic and diastolic blood pressure and smaller diameter of aneurysm. The number of both all aneurysms and RAAAs per year was significantly higher in group II. The improved preoperative status of the patients and more aggressive surgical approach are associated with reduction in in-hospital mortality of patients with RAAA. The increased experience of the center may also improve outcome of RAAA.

 

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Introduction 

Rupture of abdominal aortic aneurysm (RAAA) is a significant cause of mortality in the elderly population. In the United Kingdom it accounts for a similar number of deaths as gastric, esophageal, and prostatic malignancies.1 The number of patients with aortic rupture is increasing.2 Though great progress has been achieved in many fields of clinical medicine, the in-hospital mortality in patients with RAAA remains at a constant, high level.3, 4, 5, 6 The Department of General and Vascular Surgery of Poznan University of Medical Sciences is a tertiary reference center for vascular surgery for the province of Wielkopolska, inhabited by more than 3 million people; and the great majority of patients with RAAA from that region are referred to our center. The purpose of this study was to review our 18-year experience with RAAA to assess potential reduction in in-hospital mortality and identify factors which could be responsible for the improved results.

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Material and Methods 

Two hundred forty-six consecutive patients with RAAA admitted to the Department of General and Vascular Surgery from January 1987 to March 2005 were retrospectively analyzed. Patients with symptomatic but not ruptured aneurysms were not included in the study. There were 219 (89%) men and 27 (11%) women in the group. The mean age of patients was 69.6 (±8.6) years. Women were slightly older than men, 71.4 (±7.9) years vs. 69.4 (±8.7) years; but the difference was not statistically significant (p = 0.22, Mann-Whitney test). The median aneurysm diameter was 78 (44-150) mm. The mean and median values of systolic and diastolic blood pressure, complete blood count, and creatinine and urea serum levels recorded on admission as well as the duration of symptoms prior to admission and distance from the patient's domicile to the department are shown in Table I.

Table I. Mean and median values of analyzed factors in all patients and in groups I and II (Mann-Whitney U-test)
All patients mean (SD) [median]Group I mean (95% CI) [median]Group II mean (95% CI) [median]P
Distance from the department (km)42.8 (42.9) [36]39.5 (30.1-49.0) [22]45.6 (37.6-53.7) [38]NS
Duration of symptoms (hr)46.2 (65.1) [20]66.9 (18.5-115.3) [24]40.6 (27.8-53.3) [19]NS
Diameter of aneurysm (mm)80 (20) [78]84 (77-90) [80]76 (72-81) [75]0.04
Systolic blood pressure at admission (mm Hg)92 (46) [90]77 (63-91) [80]103 (94-112) [100]0.005
Diastolic blood pressure at admission (mm Hg)55 (32) [60]47 (37-56) [50]61 (54-68) [70]0.006
Hemoglobin (mmol/L)6.62 (1.44) [6.7]6.26 (5.89-6.64) [6.48]6.82 (6.50-7.15) [6.94]0.02
Hematocrit (%)31.5 (6.9) [32.3]29.7 (27.8-31.6) [31.3]32.50 (31.0-34.0) [33.9]0.02
Erythrocytes (× 1012/L)3.6 (0.8) [3.7]3.43 (3.23-3.64) [3.48]3.70 (3.51-3.88) [3.88]0.04
Leukocytes (× 109/L)13.5 (5.3) [13]13.6 (11.9-15.4) [12.4]13.4 (12.3-14.5) [13.3]NS
Platelets (× 109/L)212 (88) [202]174 (149-199) [182]229 (209-248) [215]0.002
Serum urea (mmol/L)10.24 (6.86) [8.01]9.29 (7.09-11.50) [8.01]10.60 (8.55-12.66)[8.17]NS
Serum creatinine (μmol/L)172.8 (153.6)[124]177.8 (117.4-238.1) [152.80]168.0 (122.7-213.3) [114.60]NS

95% CI, 95% confidence interval; NS, not significant.

To test the hypothesis that the results improved during the study period, the patients were divided into two groups. Group I consisted of 111 patients treated in the years 1987-2000, and group II consisted of 135 patients treated in the years 2001-2005. The groups were compared with regard to in-hospital mortality in all admitted patients (hospital mortality) and in operated patients (operative mortality). Variables which could potentially influence the outcome of treatment, such as age, gender, distance from the vascular surgery department, duration of symptoms, diameter of the aneurysm, systolic and diastolic blood pressure at admission, preoperative hemoglobin, hematocrit, erythrocytes, leukocytes, platelets, serum urea levels, and serum creatinine levels, were compared between the groups. Numbers of nonoperative, intraoperative, and postoperative deaths were determined in both groups. To determine the influence of the experience of the department in the surgical management of AAAs, the numbers of all patients with AAAs and of patients with RAAA treated per year were compared between the groups. The data were obtained from the analysis of patients' hospital files, operation notes, and hospital admission and discharge files.

Statistica software (StarSoft, Inc. Tulsa, OK) was used for statistical analysis. The Mann-Whitney U-test for continuous variables and Fisher's exact test for categorical variables were used. The differences were considered statistically significant at p < 0.05.

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Results 

Both hospital mortality and operative mortality were lower in group II compared with group I, 50.6% vs. 70.0% and 49.6% vs. 62.5%, respectively. However, only the difference in hospital mortality reached statistical significance (p = 0.006). The difference in operative mortality approached statistical significance (p = 0.07). The percentage of patients who were operated on was higher in group II than in group I, 94% and 79%, respectively (p = 0.0008). The two groups were similar with respect to gender (p = 0.94). Patients from group II were slightly older than patients from group I, 70.4 and 68.7 years, respectively. The difference, however, was not statistically significant (p = 0.47).

The differences in preoperative blood morphology, blood pressure, serum urea and creatinine levels, diameter of the aneurysm, duration of symptoms, and distance to the department between the two groups are presented in Table I. At admission, patients from group II had significantly higher systolic and diastolic blood pressure and levels of hemoglobin, hematocrit, red blood cells, and platelets than patients from group I. The aortic diameter was significantly smaller in group II compared with group I. There were not any statistically significant differences with regard to distance to the department, duration of symptoms, white cell count, serum urea levels, and creatinine levels between groups I and II. The median numbers of all admitted patients with AAA per year were 46 in group I and 138 in group II, and the median numbers of admitted patients with RAAA per year were seven for group I and 28 for group II. Both differences were statistically significant, p = 0.0007 and p = 0.003, respectively.

Different death patterns were found in the two groups. In both groups postoperative deaths in the intensive care unit (ICU) dominated. In group II, however, the nonoperative and ICU mortality rates were significantly lower compared to group I, 6% and 21% (p = 0.0008) and 35% and 51% (p = 0.04), respectively. No differences in intraoperative mortality and post-ICU mortality were noted. There were not any statistically significant differences in preoperative values of hemoglobin, hematocrit, red blood cells, and platelets between operated and nonoperated patients in groups I and II (Fig. 1).

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  • Fig. 1 

    Preoperative values of hemoglobin, hematocrit, red blood cells, and platelets between operated and nonoperated patients in groups I and II (Mann-Whitney U-test).

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Discussion 

In the present study a decrease in in-hospital mortality of patients with RAAA during the study period was shown. The data found in the literature are inconsistent. There are studies which did not show any significant change in in-hospital mortality,3, 4, 6, 7, 8, 9, 10 and there are papers which reported reduction in in-hospital mortality during a studied period.11, 12, 13, 14 Bown et al.,15 in their meta-analysis of 171 studies, plotted the mid-date of the study against operative mortality and found limited but definite improvement in operative mortality over time. Most of the studies that report reduction in mortality attribute it, without proof, to better operative technique and postoperative care.11, 12 There are a few studies in the literature which try to identify factors responsible for the improvement, and they focus on intraoperative factors such as supraceliac aortic cross-clamping or postoperative factors such as immediate tracheostomy.13, 14 Our study, to the best of our knowledge, is the first that shows that reduction in in-hospital mortality in patients with RAAA over the study period could be caused by a better preoperative hemodynamic status of patients as reflected by the higher values of systolic and diastolic blood pressure, hemoglobin, hematocrit, erythrocytes, and platelets. Previous studies by our group and other authors have shown that these parameters significantly influence early mortality in patients with RAAA.16, 17, 18, 19, 20, 21, 22 One could suppose that this improvement in preoperative patient status was caused by faster diagnosis and faster transfer to the vascular surgery center. That supposition is supported by a significant increase in the number of patients with RAAA per year in group II compared with group I. However, in this study the duration of symptoms of rupture did not differ significantly between the two groups. It is also unclear if the increase in the number of patients with RAAA represents a truly increased incidence or better detection. It could also be speculated that other surgical centers in the region started to operate on RAAA and that patients had to travel shorter distances before reaching the operating table. We did not, however, observe any differences in distance from the patients' domiciles and our center between the groups. Moreover, both our and other authors' previous studies failed to prove any association between duration of symptoms, the distance traveled by the patient with RAAA, and increased in-hospital mortality.16, 18, 23, 24 The other possible explanation could be that the patients received better treatment before reaching our center, but because we did not collect data on that association, this assumption is only speculative.

The numbers of all patients with AAA as well as patients with RAAA treated per year were higher in group II, and this could contribute to the greater experience of the center and influence positively the results of treatment of patients with RAAA. This idea is supported by the work of Dimick et al.,25 who found that death rates after repair of RAAA were lower at high-volume hospitals, performing more than 30 intact AAA repairs per year, compared with low-volume hospitals, performing fewer than 30 intact AAA repairs per year.

The median aortic diameter was smaller in group II compared with group I. This finding most probably reflects better detection of nonruptured aortic aneurysms and increased number of elective aortic aneurysm repairs. Previous studies, however, did not show any association between in-hospital mortality from RAAA and the diameter of the aneurysm.11, 16, 26 That is why we think that the decreased in-hospital mortality in group II was not caused by the reduction of RAAA diameter during the study period.

On the other hand, we could say that the improved outcome of RAAA was caused by a more aggressive surgical approach to these patients. The percentage of nonoperated patients decreased significantly during the study period. That change could be caused, of course, by better status of admitted patients; but surprisingly, we did not find any significant difference with regard to preoperative blood pressure and full blood count between operated and nonoperated patients in the two groups. That is why we believe that the decreased number of nonoperative deaths was mainly caused by a more aggressive surgical approach.

Analyzing the changes in mortality, besides the drop in nonoperative deaths, a decrease in ICU deaths was observed and the number of intraoperative deaths remained at the same level. Thus, a more aggressive surgical approach did not increase intra- and early postoperative mortality. A decrease in ICU deaths could be caused either by improved ICU treatment or by better immediate postoperative status of patients. To answer these questions, further studies are required.

In conclusion, we may say that better preoperative status and a more aggressive surgical approach to patients with RAAA are associated with reduction in in-hospital mortality. Methods of optimization of preoperative status of patients with RAAA should be further investigated. The greater experience of the center may also have contributed to the improvement of outcome after rupture of AAA.

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References 

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PII: S0890-5096(07)00332-9

doi:10.1016/j.avsg.2007.09.006

Annals of Vascular Surgery
Volume 22, Issue 1 , Pages 25-29, January 2008

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