Ruptured Abdominal Aortic Aneurysm: Does Trauma Center Designation Affect Outcome?
Article Outline
Ruptured abdominal aortic aneurysm (RAAA) continues to be a major cause of mortality in the United States. Rapid diagnosis and uncomplicated surgical repair remain paramount to improving survival in this population. We proposed that the addition of an organized trauma service and subsequent improved management of critically ill patients who present with RAAA would positively impact overall mortality. A retrospective analysis was performed on all patients treated for RAAA at Santa Barbara Cottage Hospital for the years 1985-2004. Patients treated before level II trauma center designation (1985-1999) were compared to those treated after the trauma center was instituted. A total of 76 patients were included in this analysis. The two groups were similar with regard to demographics. However, significant decreases in transport time from the emergency department to the operating room and overall 30-day mortality were seen in patients after the trauma center designation. This designation also led to an increase in the number of cases performed per year, centralizing the treatment for these critically ill patients. Institution of a well-prepared and organized service, such as trauma, improved the outcome for patients treated with RAAA, with a particular benefit in the unstable patient.
Introduction
Ruptured abdominal aortic aneurysm (RAAA) continues to be a major cause of mortality in the United States. RAAA currently ranks fifteenth among all causes of death for men in the United States each year.1 Expedient diagnosis and uncomplicated surgical repair remain of paramount importance to improving the chances of survival in this population. However, even with advances in surgical and perioperative care, RAAA is associated with a mortality rate of 45-58% and an overall mortality of 75-90%, including prehospital deaths. These dismal mortality rates have not significantly improved in the past 20 years.1, 2, 3, 4, 5 Many factors have been discussed in the literature with regard to predicting mortality in patients with RAAA. These factors include blood pressure, hemoglobin level, creatinine level, blood transfusion requirement, temperature, cardiac arrest, acidosis, age, and female gender.6, 7, 8 Certainly, all physicians treating RAAA agree that these patients need operative intervention as quickly as possible since delays in transport to the operating room are associated with increased mortality.9 This often requires an organized team approach with designated operating rooms and staff for support.
Santa Barbara Cottage Hospital is a 350-bed community teaching hospital. In 1999 the hospital was first designated as a level II trauma center by the American College of Surgeons. In order to achieve and maintain this designation, a dedicated trauma team consisting of a surgeon, resident physician staff, anesthesiology, neurosurgery, orthopedics, on-call nurses, and ancillary staff must be well prepared to rapidly assess and treat critically ill patients. Although not specifically designed to treat vascular emergencies, this team remains equipped to handle all surgical emergencies.
We proposed that the addition of this organized trauma service and subsequent improved management would positively impact overall mortality for patients presenting with RAAA.
Methods
A retrospective analysis was performed for all patients treated for RAAA at Santa Barbara Cottage Hospital between February 1985 and December 2004. All patients refusing surgical intervention were excluded. After institutional review board approval, all patient charts were reviewed based on Current Procedural Terminology (CPT) codes for ruptured infrarenal AAAs. Demographic and preoperative factors recorded included age, sex, comorbidities, blood pressure, and transport time from the emergency department to the operating room. In addition, intraoperative and postoperative data were gathered. Primary outcome was 30-day mortality.
The patients were stratified into two groups: those treated from 1985 to 1999 before the level II trauma center designation (group I) and those treated after the designation (group II). The patients were further evaluated with respect to hemodynamic status on arrival as stable versus unstable. Unstable patients were defined as those with a recorded systolic blood pressure of <90 mm Hg on presentation to the emergency room. In addition, distance traveled to the hospital was recorded.
Data were analyzed using GraphPad® (GraphPad, San Diego, CA) software. Groups were compared using Student's two-tailed t-test. Statistical significance was achieved at P < 0.05.
Results
A total of 100 patients were treated at our institution for RAAA from 1985 to 2004. Twenty-four patients refused treatment, and all expired. The remaining 76 patients underwent open repair of RAAA and are the focus of this report.
Group I consisted of 44 patients with RAAA treated from 1985 to 1999 and group II consisted of 32 patients cared for after 1999 when the level II trauma center was instituted. Demographics of the groups are depicted in Table I. The groups were equivalent regarding age, sex, and comorbid factors. In addition, presence of hemodynamic instability did not significantly differ between the groups: 14 patients in group I and 10 patients in group II.
Table I. Demographics
| Characteristic | Group I | Group II |
|---|---|---|
| Number of patients | 44 | 32 |
| Unstable patients | 14 | 10 |
| Male gender (%) | 70 | 75 |
| Mean age (years) | 78.3 (range 53-94) | 73.2 (range 60-94) |
| Diabetes (%) | 20 | 21 |
| Hypertension (%) | 65 | 67 |
| Coronary artery disease (%) | 25 | 22 |
The mean time to transfer to the operating room and 30-day mortality are shown in Table II. A decrease in time from the emergency room to the operating room was seen after level II trauma center designation. In addition, an improvement in 30-day mortality was seen in patients treated for RAAA after level II trauma center designation.
Table II. Overall time to the operating room and 30-day mortality
| Characteristic | Group I | Group II | P |
|---|---|---|---|
| Time to the OR (min) | 125 | 80 | 0.001 |
| 30-day mortality (%) | 73.5 | 46.8 | 0.02 |
Further stratification into hemodynamic stability is shown in Table III, Table IV. Hemodynamic instability was defined as admission systolic blood pressure <90 mm Hg. A significant improvement in time to the operating room from the emergency department was seen with both stable and unstable patients after the level II trauma center designation. The 30-day mortality in unstable patients was also improved. This same improvement in mortality was not significant in stable patients presenting with RAAA. There were no differences in the mortality of patients when analyzed for distance traveled to the hospital.
Table III. Stable patients
| Characteristic | Group I (n = 30) | Group II (n = 22) | P |
|---|---|---|---|
| Time to the OR (min) | 144 | 103 | 0.01 |
| 30-day mortality (%) | 63 | 40 | 0.057 |
Table IV. Unstable patients
| Characteristic | Group I (n = 14) | Group II (n = 10) | P |
|---|---|---|---|
| Time to the OR (min) | 84 | 31 | 0.001 |
| 30-day mortality (%) | 85.7 | 60 | 0.04 |
Although there was an increase in the number of RAAA cases treated per year, three per annum in group I and eight per annum in group II, no difference was seen in individual surgeons who operated in both time periods regarding 30-day mortality.
Discussion
Continued high mortality rates for patients treated for RAAA has been the subject of much debate. Even with advances in operative and perioperative care, mortality still frequently approaches 70%.1, 2, 3, 4, 5 These poor results have prompted authors to evaluate factors associated with mortality and to consider nonoperative therapy. These include initial blood pressure, hemoglobin level, creatinine level, blood transfusion requirement, temperature, cardiac arrest, acidosis, age, and female gender.6, 7, 8, 9, 10 In addition, presence of medical comorbidities has been evaluated.
All authors agree that rapid transport, evaluation, and uncomplicated operative treatment of RAAA remain of paramount importance to optimizing survival in these patients. A delay in diagnosis in the emergency department was associated with increased mortality in a previous study by Pannetan and colleagues.11 Increased time in the operating room was also associated with increased mortality in a study by Wakefield et al.,12 with >4 hr operating time being a significant predictor of mortality.
Our study sought to evaluate the treatment of critically ill patients with a diagnosis of RAAA. More specifically, we evaluated the outcome in patients treated with RAAA before and after designation as a level II trauma center. This requires an institution to have a 24 hr call team consisting of a general surgeon, specialty surgeons, resident staff, nurses, and ancillary services. This team is prepared to handle trauma cases. In addition, a secondary benefit of this organized team is to improve care of other surgical emergencies such as RAAA. Both trauma patients and unstable surgical patients are assessed and treated quickly by in-house resident physician staff. Operating room facilities and staff are then rapidly mobilized.
Our analysis showed a significant improvement in outcome after the trauma center designation. Decreased transport time from the emergency department to the operating room was seen for all patients regardless of hemodynamic stability. In addition, 30-day mortality was significantly improved in patients treated for RAAA after trauma center designation. This was not significant for patients presenting with a stable hemodynamic profile.
One reason for the decreased mortality after the trauma center designation was the decreased time to the operating room. Two other recognized factors for improved outcome were also identified. First, several studies have shown that increased volume in both the center itself and individual surgeons lead to improved outcome in patients with RAAA.9, 11 In 1997, a fellowship-trained vascular surgeon joined our community with an increased volume of elective aortic aneurysm repairs. Although the outcome for those patients treated for RAAA by this surgeon was improved compared to the other surgeons, this variable did not reach significance. In addition, the volume of patients treated for RAAA increased after the level II trauma center designation. This volume more than doubled to eight RAAAs per year. Once again, this was a product of centralization of care for these critically ill patients to our institution. This effect has been documented in other reports.8
Overall, RAAA carries a significant mortality, and optimizing care is critical to improving mortality rates. Our data clearly show the benefit of an organized service to centralize the management of these critically ill patients. This allows rapid utilization of resources and hastens time to the operating room, resulting in an improvement in overall survival. Although a designated trauma service may not be feasible for every community hospital, we have demonstrated the importance of having a well-prepared service to improve the outcome in patients with RAAA. The study supports the improvement in patient survival related to increased case volume, with the greatest benefit for the unstable patient.
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Presented at the 23rd Annual Meeting of the Southern California Vascular Surgical Society, La Quinta, CA, May 13-15, 2005.
PII: S0890-5096(07)00067-2
doi:10.1016/j.avsg.2007.01.003
© 2007 Annals of Vascular Surgery Inc. Published by Elsevier Inc All rights reserved.
