Prehospital Treatment of Infrarenal Ruptured Abdominal Aortic Aneurysms: A Multicentric Analysis

Article Outline

• Abstract
• Introduction
• Methods
• Results
• Discussion
• Conclusions
• Acknowledgment
• References
• Copyright

Background

The aim of this study was to evaluate the quality of the current treatment of patients presenting with ruptured abdominal aortic aneurysms (RAAAs), from the first symptoms to the operating room with an analysis of preoperative mortality risk factors.

Methods

For 3 years, in four vascular surgery departments, we have collected all the consecutive cases of patients operated on for RAAA. We analyzed the initial clinical situation, the means of transportation, the time elapsed before treatment, and the mortality rate at 3 days. Sixty-six RAAAs were operated on. Mean patient age was 76 years (range, 52–93 years).

Results

The initial symptoms were a precisely located pain either abdominal (45.3%), lumbar (17.2%), or both (14.1%) or feeling faint (10.9%). In 22.7% of the cases, an initial hemodynamic instability was observed. In 46.8% of the cases, patients first went to a peripheral hospital before being admitted into a referral centre. In 84.5% of the cases, medical mean of transportation was used. The mean distance covered was 59.8 kilometers (range, <5 km to 213 km). The initial diagnosis was accurate in 67.3% of the cases. The mean intrahospital waiting period between the arrival at a reference center and the admission into an operating room was 127minutes. Global mortality rate was 44.2%. The main preoperative mortality factor to be noticed was the initial hemodynamic instability (p=0.0031). Among stable patients, only two of them (5.4%) worsened during the preoperative treatment.

Conclusion

In our study, hemodynamic instability corresponds to the main prognosis factor of mortality. In most cases, the initial stability persisted and allowed additional evaluation. However, the intrahospital waiting periods appeared to be too long. To be optimal, the adequate treatment should be specifically designed as soon as a diagnosis has been established.

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Introduction 

According to recent studies, the current prevalence of abdominal aortic aneurysms (AAAs) is between 1.3% and 8.9% for men and between 1.%0 and 2.2% for women.¹, ² For the next coming decades, these rates are very likely to significantly increase since people are living longer and tobacco addiction remains important.³ Therefore, an increase in aneurysmal rupture is a concern, which is the very last progressive complication of AAAs. Rupture (RAAA) still leads to dreadful consequences: according to the series, global mortality rate ranges from 50% to 80%,³ with a mortality peak occurring during the first minutes following a rupture. During the past decades, this rate has slightly improved, but much of the credit should go to resuscitation rather than to surgery.⁴

Endovascular surgery currently represents the most important advance in AAA elective treatment and several authors have investigated its efficiency for treating RAAAs in emergency conditions.⁵, ⁶, ⁷

However, improvement of the prehospital course is rarely taken into consideration, although probably being the most delicate period following arupture.

Taking several University Hospital Centers (UHC) experiences as references, the aim of this study was to evaluate this treatment by analyzing the patients' initial clinical chart, the successive stages in their therapeutic management, the waiting periods, and the mortality factors.

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Methods 

This retrospective multicentric study concerns the Besançon, Strasbourg, Dijon, and Reims UHCs. The data were collected from the treatment files that had been filled in by the physicians of the different emergency medical services (EMS) from the beginning of their intervention to the transportation to a referral center.

This study was carried out over a period of 3 years, from January 2003 to December 2005. We have consecutively included all the patients operated on for RAAA in the four UHCs. RAAA was diagnosed when a perianeurysmal hematoma had been found as a result of surgical exploration or preoperative examinations (abdominal ultrasound or abdominopelvic CT scan). Nonoperated RAAAs were excluded as well as AAAs operated in the emergency department but not ruptured, aortoenteric or aortocaval fistulas, and ruptures on atherosclerotic plaques (without an aneurysm). The data that were taken into consideration included the patient's history (age, gender, smoking, diabetes, hypercholesterolemia, high blood pressure [HBP], obesity, cardiac comorbidities [cardiopathy, history of myocardial revascularization, myocardial infarction, angor, or cardiac insufficiency], respiratory insufficiency, renal insufficiency, detection of AAA before rupture, presence of a hostile abdomen with a previous laparatomy, or an abdominal pathology increasing the operative risk of conventional surgery), initial characteristics of the rupture such as patient's location (personal home, nursing home, peripheral hospital, UHC), identity of the person who called (patient, family, physician in attendance, emergency physician, others [e.g., neighbor]), reason for calling (abdominal or lumbar pain, or both, feeling faint, loss of consciousness), description of the initial clinical status (hemodynamic instability defined by the need for catecholamines, consciousness), and initial clinical diagnosis.

The transportation was analyzed in terms of type of vehicle (emergency mobile unit [EMS vehicle], private ambulance, EMS helicopter, emergency vehicle for asphyxiated or injured people, others), patient conditioning (placement of a peripheral venous access or of a central venous access or use of an antishock garment [ASG]), clinical status (stable or hemodynamic instability), distance (kilometers), and transportation duration (minutes).

Four waiting periods were collected: the waiting period between the first symptoms and the admission into operating room (total preoperative waiting period), the waiting period for patient's transportation to a referral center (EMS vehicle or others) (transportation waiting period), the waiting period between the admission into a hospital center and operating room (intrahospital waiting period), and the waiting period between the arrival to CT scan (TDM) and the entrance into the operating room (CT waiting period).

The analysis of surgery specified the type of surgery, the level of aortic clamping, clamping and surgery duration, the estimated blood loss, the quantity of blood units transfused, and the highest and lowest systolic pressure measurements.

Postoperative course was analyzed for peroperative or postoperative (30 days following surgery) death rates and the causes of postoperative death.

We carried out a statistical analysis to detect the predictive factors of global mortality by applying a χ² test with a significance level of p=0.05. The insufficiently documented criteria that could not ensure statistical test validity were not taken into consideration. The percentage calculation of each criterion was based on well-documented valid data. All the data were treated with Microsoft Office programs and the statistical program SPSS 10.0 (SPSS, Chicago, IL).

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Results 

Sixty-six patients with RAAA were operated during the period of 2003 to 2005. Mean patient age was 76 years (range, 52-93 years). There were 60 men and 6 women (Table I). Mean aneurysmal diameter was 75mm (range, 30-120mm). Regarding the patients' main medical history (Table I), 68% were current smokers and 67% had HBP. In 37.2% of the cases, the AAA was already known.

Table I. Study Population

	N	%
Males (n=66)	60	91
Females (n=66)	6	9
Age over 80 (n=58)	16	27.6
Tobacco addiction (n=47)	32	68.1
Diabetes (n=43)	8	18.6
Hypercholesterolemia (n=41)	20	48.8
HBP (n=48)	32	66.7
Hostile abdomen (n=42)	16	38.1
AAA detected (n=51)	19	37.2

HBP, high blood pressure; AAA, infrarenal abdominal aortic aneurysm.

In 46.7% of the cases, the first telephone call to the physician on attendance for emergencies was given from a private home or from a nursing home; 46.8% were from an intermediary hospital center; and 6.5% were from a referral center. In 54.9% of the cases, an emergency physician had decided to call. The reason for calling (Table II) was mainly pain (76.6%): abdominal pain (45.3%), lumbar pain (17.2%), or abdominal and lumbar pain (14.1%). In 63.7% of the cases, the initial diagnosis given by the emergency physician was accurate. Clinically, 15 patients (22.7%) were presenting with an initial hemodynamic instability and the treatment required intubation in 31% of the cases.

Table II. Initial Characteristics

	N	%
Patient's localization (n=62)
Personal home	26	41.9
Nursing home	3	4.8
Intermediary hospital center	29	46.8
University hospital center	4	6.5
Identity of the first person to call (n=51)
Patient	4	7.8
Family	3	5.9
Physician in attendance	9	17.6
Emergency physician	28	54.9
Other	7	13.7
Reason for calling (n=64)
Isolated abdominal pain	29	45.3
Isolated lumbar pain	11	17.2
Abdominal and lumbar pain	9	14.1
Feeling of sickness or lost of consciousness	7	10.9
Other	8	12.5
Correct initial diagnosis (n=55)	37	67.3
Conscious patient (n=44)	32	72.7
Intubated patient (n=42)	13	31
Hemodynamic instability and/or initial cardiorespiratory (n=66)	15	22.7
Hemodynamic degradation before arriving in an operating theater (n=52)	2	5.4
CT scan examination before arriving in the operating theater (n=66)	54	82

n=documented cases.

In 84.5% of the cases, patients were transported by EMS (Table III) with placement of a peripheral venous access in 91% of the cases. Mean transportation distance was 59.8 km (range, 5-213 km). During transportation, only two hemodynamic instabilities occurred (5.4% of the cases) (Table II). It was not possible to obtain consistent data that would have enabled us to calculate treatment waiting periods. The only reliable data concerned the intrahospital waiting period, with a mean 127-minute duration (Table IV).

Table III. Transportation Means to the Referral Center

	N		%
Type of transport (n=58)
EMS vehicle	42		72.4
EMS helicopter	7		12.1
Private ambulance	4		6.9
Emergency vehicle for asphyxiated or injured people	1		1.7
Other	4		6.9
Conditioning (n=55)
Peripheral venous access	50		91
Associated central venous access	5		9
ASG (n=38)	16		42.1
Distance>50 kilometers (n=55)	31		56.4
	Mean	Minimum	Maximum	Standard deviation
Distance in kilometers (n=55)	59.8	5	213	+/- 41

EMS, emergency medical services; ASG, antishock garment.

Table IV. Mean Waiting Periods (in minutes)

Type of Waiting Periods	Mean (min)
Total preoperative waiting period (n=15)	225
Transportation waiting period (n=19)	65
Intrahospital waiting period (n=40)	127
TDM waiting period (n=12)	105

Total preoperative waiting period, the waiting period between the first symptoms and the admission into operating room; transportation waiting period, the waiting period for patient's transportation to a referral center (EMS vehicle or others); intrahospital waiting period, the waiting period between the admission into a hospital center and operating room; CT waiting period: the waiting period between the arrival to CT scan (TDM) and the entrance in operating room.

Surgery consisted of standard open technique with aortoaortic prosthetic replacement in 52% of the cases, aorto-bi-iliac in 28% of the cases, and aortobifemoral in 18% of the cases (Table V). Infrarenal clamping was performed in 61.5% of the cases and suprarenal clamping in the other cases. Mean clamping duration was 98.6minutes (range, 30-240minutes), and mean surgery duration was 246minutes (range, 60-465minutes).

Table V. Characteristics of surgical interventions

	Mean	Minimum	Maximum	Standard deviation
Lowest systolic BP (n=51)	51.8	0	100	25.76
Highest systolic BP (n=50)	162.64	30	210	36.98
Blood units transfused (n=51)	6.9	2	24	4.34
Surgery duration in min (n=48)	246.27	60	465	85.74
Clamping duration in min (n=43)	98.6	30	240	47.35

Type of surgery (n=50)	N	%
Aorto-aortic by-pass	26	52
Aorto-biiliac by-pass	14	28
Aorto-bifemoral by-pass	9	18
Other	1	2

Fourteen patients died during surgery, one of them before incision (21.1% peroperative deaths). Thirteen additional patients died during the postoperative period (i.e., 19.6% of the operated-on patients); 8 patients had multivisceral deficiency, 4 had myocardial infarction, and 1 had respiratory insufficiency. Global mortality amounts to 44.2% (Table VI). The only concrete factor of preoperative mortality (Table VII) was an initial hemodynamic instability (p=0.0031). A preoperative factor was discovered: transfusion of more than 10 blood units (p=0.02).

Table VI. Immediate and 30 days postoperative course, causes of postoperative deaths

	Number	%
Deaths (n=61)
Preoperative	1	1.6
Peroperative	13	19.6
Postoperative	13	19.6
Total	27	44.2
Causes of postoperative deaths
Multivisceral deficiency	8	61
Cardiological complications	4	31
Pulmonary complications	1	8

Table VII. Preoperative and peroperative mortality factors

	P
Initial hemodynamic instability (n=66)	0.0031
More than 10 blood units transfused (n=51)	0.02

X² test.

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Discussion 

This multicenter study is interesting because it describes the details of the present RAAA treatment up to the admission into the operating room; this topic has not often been dealt with in the literature. The goal of this mainly descriptive work was to objectively analyze the different stages that have to be withstood by patients whose vital prognosis is at stake and who require rapid transportation to an operation room to undergo hemostasis.

We were able to notice that half of the patients went first to an intermediary hospital center before being admitted into a referral center (Table II); five of these patients were initially hemodynamically unstable (Table VIII). This stage, which very likely increases the waiting period, should, in principle and for the patients' benefit, help confirm the diagnosis and organize medical transportation. In our series, most patients (84.5%) were transported in medical vehicles. Similarly, in 67.3% of the cases, the initial diagnosis was correct with adequate conditioning (placement of a peripheral venous access in 91% of the cases). In 82% of the cases, one TDM was performed, which gives future prospects to consider endovascular treatment.

Table VIII. Main characteristics of prehospital treatment according to the initial hemodynamic status

	Initial hemodynamic stability (n=51)	Initial hemodynamic instability (n=15)	Total (n=66)
Patient's location
Personal home	18	8	26
Nursing home	2	1	3
Intermediary hospital center	24	5	29
Referral center	3	1	4
Missing data (Lack of data)	4	0	4
Type of transport
EMS vehicle	28	14	42
EMS helicopter	4	0	4
Private ambulance	7	0	7
Emergency vehicle for asphyxiated or injured people	1	0	1
Other	3	1	4
Missing data	8	0	8
Intra-hospital waiting period∗ (n=40)	135	45	127
Preoperative TDM (n=66)	45	9	54
Mortality at 30 days	18	9	27
Missing data	5	0

In our series, the only well-documented and therefore exploitable waiting period is the intrahospital waiting period: it represents the time elapsed between the admission into a referral center and the admission into an operating room with a 127-minute mean time for all the patients (135minutes for stable patients and 45minutes for unstable patients (Table IV, Table VIII). These waiting periods are longer than the data found in the recent literature: Farooq et al.⁹ gave a 30-minute estimation and Johansen et al.⁸ gave a mean 12-minute estimation. According to our experience, these differences can be explained by diagnosis errors (32.7% of the cases), the great number of people intervening (physicians from the EMS, from the emergency hospital service, and from the medical-surgery team) and, above all, by the lack of specific protocol of routing concerning this pathology.

Among initially hemodynamically stable patients, most of them remained stable despite the waiting periods (94.6%, Table II). It is a general belief that prognosis is determined by the AAA rupture location. Rupture in the free peritoneal cavity leads to a cataclysmic hemorrhage with patient's rapid death; a retroperitoneal rupture benefits from a tamponnement that stabilizes the situation for a variable time. Farooq et al. have thus demonstrated that, in comparison with unstable patients, stable patients were less likely to die despite longer waiting periods⁹; this seems to be also the case in our study (Table VIII). If stable patients can therefore benefit from all the advantages of early medical management, such as is now carried out, the issue still concerns instable patients whose hemorrhage should be controlled in a very short time. In our series, initial hemodynamic instability was the only preoperative mortality cause, which demonstrates that initial hemorrhage has an impact on the prognosis.

Primary hemodynamic instability, in association with clinical signs (abdominal and/or lumbar pain) suggesting the prognosis, should justify a rapid treatment in a regional referral center without going through an intermediary center and be treated as RAAA until there is proof to the contrary. In our study, unstable patients had to withstand very complicated stages before a definitive treatment (5 of them went to an intermediary center and 9 underwent TDM) and their intrahospital waiting times were far too long (mean time, 45minutes) (Table VIII). These two snags reduce the patients' chances.

Many authors have shown concern about how to deal with noncontrolled hemorrhages and most of them have concluded that it was not efficient to immediately try and stabilize them. ASGs were notably used in our series (16 patients of 38 well-informed cases). Mattox et al.¹⁰ have shown a excessively high death rate due to the use of ASGs during transportation waiting periods greater than 30minutes, which is probably the case in our study (mean time, 65minutes for 19 well-informed cases; Table VI). Terai et al.¹¹ have noticed an increased need of O₂ in patients wearing ASGs, which can entail a patient's intubation with consequences such as abdominal muscles slackening, reduced perianeurysmal tamponnement, and active hemorrhage. Moreover, Hirscberg et al.¹² wonder about the usefulness of the increase of arterial blood pressure observed with this technique, which may reactivate the bleeding.

The same authors have confirmed the efficiency of haemostatic hypotension.¹², ¹³, ¹⁴, ¹⁵ In fact, blood leaking is proportional to mean haemodynamic stability,¹⁶ and when this haemodynamic stability is decreasing, it leads to a more effective tamponnement with the occurrence of a hemostatic thrombus on the effraction and maintaining a minimal haemodynamic stability. The different maneuvers to keep a theoretically satisfying mean blood pressure (filling, garment) would be as many obstacles that would prevent hemostatic thrombus occurrence.¹² In the particular set of problems concerning RAAAs, the hemostatic hypotension principle has only been demonstrated with experimental models but not in patients.¹⁷ Moreover, this stability is temporary, with a secondary active hemorrhage, which requires every RAAA to be rapidly treated until hemorrhage is under control.¹²

In the literature, present data confirm that stable as well as unstable patients must be transported as quickly as possible to a referral center. Whenever initial clinical examination may suggest AAA rupture, and especially in case of hemodynamic instability, a very specific treatment should be set up with rapid transportation to a referral center and the hemostatic hypotension principle should be applied.

In our experience, the great difficulties in obtaining information about the different waiting periods clearly underline how little we know about current RAAA treatment (Table IV). To try to improve RAAA surgery results, a treatment evaluation has to be carried out, which we partially achieved. Moreover, this study did not take into account patients who died before arriving in an operating theater, which restricts the relevance of the analysis. A prospective work that would imply all the concerned people would certainly help find answers to the questions this study has brought up when an AAA rupture is suspected.

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Conclusions 

In our experience, the initial hemodynamic status determines the immediate prognosis of RAAAs. A priori, primary stability allows some waiting periods, whereas hemodynamic instability results in high mortality risk. However, the different stages patients have to withstand—going through an intermediary hospital center or undergoing complementary examinations—are very complicated and reduce their chances. Intrahospital waiting periods in referral centers are also too long compared with the requirements of an ideal treatment. Whenever an AAA rupture is suspected, the different stages of a specific protocol should be set up to ensure the best results.

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The authors would like to thank Ms. Chrystelle Vidal, a biostatistician in the Centre d'Investigation Clinique of the Centre Hospitalier Universitaire de Besançon, for her valuable help concerning the methodological aspects of this study.

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