Diagnostics

Screening for extermity arterial injury withthe arterial pressure index

SA

N 55101, USA

enter, Jackson,

American Journal of Emergency Medicine (2005) 23, 689695

www.elsevier.com/locate/ajem2 Tel.: +1 651 254 1513; fax: +1 651 254 1519.3 Tel.: +1 601 984 6525.T Corresponding author. Tel.: +1 651 254 0929; fax: +1 651 254 1519.E-mail addresses: zlowi@web.de (M.P. Zlowodzki)8 mgraves@orthopedics.umsmed.edu (M. Graves), peter.a.cole@healthpartners.com (P.A. Cole).1 Tel.: +1 651 254 1515; fax: +1 651 254 3247.entity an intimidating diagnostic challenge [Johansen K, Lynch K, Paun M, et al. J Trauma

1991;31(4):515-9; discussion 519-22; Lynch K, Johansen K. Ann Surg 1991;214(6):737-41; Walker

ML, Poindexter Jr JM, Stovall I. Surg Gynecol Obstet 1990;170(2):97-105; Kendall RW, Taylor DC,

Salvian AJ, et al. J Trauma 1993;35(6):875-8].extremities. Once the diagnosis of arterial trauma is made, a multi-disciplinary approach is warranted.

The diagnostic strategies for vascular injury have undergone an evolution over the past 2 decades. One

and a half percent to 4.6% of patients hospitalized with blunt extremity trauma have associated vascular

compromise [Bunt TJ, Malone JM, Moody M, et al. Am J Surg 1990;160(2):226-8; Reid JD, Weigelt

JA, Thal ER, et al. Arch Surg 1988;123(8):942-6; Applebaum R, Yellin AE, Weaver FA, et al. Am J

Surg 1990;160(2):221-4; discussion 224-5; Dennis JW, Frykberg ER, Veldenz HC, et al. J Trauma

1998;44(2):243-52; discussion 242-3]. An efficient and effective evidence-based approach to

diagnosing vascular injury is necessary, as the difficulty in diagnosis, the multiplicity of diagnostic

strategies, the limited time frame in which to initiate appropriate treatment, the limb threatening

complications of a missed diagnosis, and the increased awareness of health care expenditures make thisBruce A. Levy MDa,1, Michael P. Zlowodzki MDb,2,Matt Graves MDc,3, Peter A. Cole MDd,*

aSports and Knee Injuries, Regions Hospital, University of Minnesota, St Paul, MN 55101, UbDepartment of Orthopaedic Surgery, Regions Hospital, University of Minnesota, St Paul, McDepartment of Orthopaedic Surgery and Rehabilitation, University of Mississippi Medical C

MS 39216-4505, USAdOrthopaedic Trauma, Regions Hospital, University of Minnesota, St Paul, MN 55101, USA

Received 1 December 2004; accepted 22 December 2004

Abstract Certain extremity injuries presenting to the ED or Trauma Unit warrant increased suspicionfor underlying arterial trauma. Such injuries include knee dislocations, displaced medial tibial plateau

fractures and other displaced bicondylar fractures around the knee, open or segmental distal femoral shaft

fractures, floating joints, gunshot wounds in proximity to neurovascular structures, or mangled0735-6757/$ see front matter D 2005 Published by Elsevier Inc.

doi:10.1016/j.ajem.2004.12.013

The purpose of this article is to present an evidence-based algorithm for patients who present with

lgorithm will be presented, and the

xt of current medical literature.

2. Screening for arterial injury

For over 2 decades, it has been recognized that physical

examination alone is not a reliable method to detect the

presence or absence of arterial injury. Different methods of

screening have been developed according to historical

context, technology, cost, and efficiency. Each screening

tests limitations led to the next diagnostic modality. Initially,

nonoperative screening was used with an emphasis on

observation before further treatment. In time of war, operative

exploration based solely on proximity of the injury to

vascular structures became the screening method of choice.

This aggressive and invasive approach occurred most often in

the context of marked soft tissue destruction that accompa-

nied high-velocity missile damage [12]. Such an approach did

not translate sensibly to low-energy civilian injuries, so the

ment of the blood pressure cuffs on

of API.

B.A. Levy et al.690Because of the inadequacy of the physical exam and the

need for prompt diagnosis and treatment, on-call and

ED physicians must prioritize patients who require evalua-

tion for possible arterial injury from extremity trauma. A

safe, efficient, cost-effective, and evidence-based algorithm

is required.Fig. 1 Example of the placethe extremities for assessmenteither arterial injury or a high-risk of arterial injury. A diagnostic a

rationale for diagnostic interventions will be discussed in the conte

D 2005 Published by Elsevier Inc.

1. Introduction

The 4 bhard signsQ of extremity vascular injury includepulsatile hemorrhage, an expanding hematoma, a palpable

thrill or audible bruit, or a pulseless limb. When a patient

presents with any of the 4 hard signs of vascular injury,

immediate surgical exploration and vascular repair are

warranted [1-4]. The exception to this rule is when the

patient presents with multilevel trauma to an extremity (eg,

a shotgun injury or an extremity with 2 fractures), in which

case the level of arterial injury may be in question and an

arteriogram is indicated.

A more difficult diagnostic problem occurs in patients

who present with more subtle clues of vascular injury. These

bsoft signsQ might include a history of severe hemorrhage atthe accident scene, subjectively decreased or unequal pulses,

decreased 2-point discrimination testing of an anatomically

related nerve deficiency, or a nonpulsatile hematoma [3].

Perhaps easier to define are the orthopedic injury patterns

that have been associated with a high incidence of arterial

damage. These orthopedic injuries include knee disloca-

tions, certain displaced tibia plateau fractures, ipsilateral

fractures on either side of the knee (floating knee), gunshot

wounds in proximity to neurovascular structures, or

mangled extremities.

The physical examination alone is often inadequate for

accurate diagnosis and therefore is not a reliable predictor of

arterial trauma [3,5]. Palpation of a pulse is a subjective

measure prone to wide interobserver variation. Furthermore,

pulses have been reported to be palpable distal to major

arterial lesions, including complete arterial disruption

[3,6,7]. Despite the limitations of the physical examination,

a precise and well-documented examination serves as a

screening tool for vascular injuries.

Expeditious diagnosis is essential, given the urgent time

frame in which to treat a patient with an arterial lesion. An

extended diagnostic interval may result in the manifestations

of arterial damage. A warm ischemia time interval of less

than 6 hours is generally accepted as the standard interval

within which arterial continuity must be restored to avoid

permanent damage to the soft tissues [8-10]. A delay in

diagnosis may result in serious complications, such as an

arteriovenous fistula, compartment syndrome, ischemic

contractures, or loss of the limb [6,11].

investigated as a screening tool for clinically significant

arterial compromise [16,21,22]. To conduct an API exam-

ination, a blood pressure cuff is placed on the supine patient

proximal to the ankle or wrist of the injured limb, and a

systolic pressure is determined with a Doppler probe at the

respective posterior tibial artery or radial artery. The dorsalis

pedis or ulnar arteries may be used as well. The same

measurement is determined on the uninjured upper or lower

extremity limb (Fig. 1). The API is calculated as the systolic

pressure of the injured limb divided by the systolic pressure

of the uninjured limb:

API Doppler systolic arterial pressure in injured limbDoppler systolic arterial pressure in uninjured limb

In a controlled trial of 100 consecutive limbs, Lynch and

Johansen [16] demonstrated when this value is less than 0.9,

the sensitivity and specificity are 95% and 97% for major

arterial injury, respectively. The negative predictive value for

an API of greater than 0.9 in the same study was 99% [16].

Using the same clinical algorithm where arteriography was

Arterial pressure index (API) 691mandatory operative approach was abandoned based on

invasiveness and high negative results [4,6,13].

Arteriography as a screening tool (exclusion arteriogra-

phy) became popular in the late 1970s and 1980s as its

techniques were continually refined. With a published

sensitivity of 95% to 100%, and a specificity of 90% to

98%, arteriography quickly became the gold standard

Fig. 2 (A) Anteroposterior (AP) and (B) lateral radiographsdemonstrating typical Schatzker IV medial tibial plateau fracture.

Although the AP radiograph shows minimal displacement, the

lateral radiograph shows that this injury represents a fracture

dislocation of the knee.[2,3,5,14]. However, the cost effectiveness of arteriography

created concern, as some authors noted the test to be overly

sensitive and management infrequently changed based on its

results [6,11,14-17]. In addition, arteriography was noted to

be time consuming and presented risks to the patient

including renal contrast toxicity, pseudoaneurysm, and even

death [14,18].

The duplex ultrasound was developed next, which

seemed to fulfill criteria for speed and accuracy, and its

effectiveness was demonstrated in multiple studies

[1,19,20]. However, the exam is operator- and interpreter-

dependent and requires a trained vascular technologist

available 24 hours a day. The best screening exam for an

arterial injury should be quick, noninvasive, portable, cost

effective, and reliable. These criteria have led to the current

standard of the arterial pressure index (API) as a screening

exam for extremity arterial injury.

3. The API

Determination of the API, also known in the literature as

the ankle brachial index or ankle arm index, requires the use

of a Doppler machine and a blood pressure cuff. It has beenFig. 3 (A) Sagittal and (B) coronal computed tomography scanshowing dissociation of the articular surface of both medial and

lateral portions of the tibial plateau from the diaphysis (shaft) of the

tibia (Schatzker type VI). The sagittal view shows significant

posterior displacement, placing the popliteal artery at risk.

suspicion in the young patient who has sustained a knee

injury from high-energy trauma. Suspicion should be further

heightened with radiographic evidence of marked fracture

displacement and/or comminution. It should be kept in mind

that the displacement of the fracture was likely much worse at

the time of injury than the static x-ray shows, as the soft

tissues return the fragments toward their original position

te knee dislocation. B and C, Angiography shows postreduction AP view

B.A. Levy et al.692limited to patients with an API less than 0.9, Johansen et al

then evaluated 100 injured limbs. In this study, 84 limbs

sustained penetrating injuries and 16 sustained blunt trauma.

Of the 17 limbs with an API of less than 0.9, 16 had positive

arteriographic findings and 7 required surgical exploration

and repair. Among the 83 limbs with an API of greater than

0.9, clinical follow-up revealed 5 minor arterial lesions but

no major injuries requiring surgical intervention. In addition,

duplex ultrasonography tests performed on 64 of the limbs

with an API of greater than 0.9 were all negative. The cost-

effectiveness of the API was also examined and showed that

over the 6O- month period, exclusion arteriograms werereduced from 14% to 5.2% of all contrast studies and

resulted in a net savings of $65175 [21].

Before this study, the API was primarily used on patients

with penetrating injuries. Orthopedists and other practi-

tioners were left to question the usefulness of the API in the

bluntly injured limb, such as a fracture or dislocation. More

recently, its efficacy has been extended to the management of

blunt extremity injury. In a controlled trial of 75 consecutive

blunt high-risk orthopedic injuries, the negative predictive

Fig. 4 A, Anteroposterior radiograph of the knee showing complewith complete occlusion of the popliteal artery.value of a Doppler API of greater than 0.9 was 100%.

Seventy percent of the 75 injured limbs had an API of greater

than 0.9, and clinical follow-up revealed no major or minor

arterial injuries. Among the 30% with an API of less than

0.9, 70% had lesions detected by arteriogram, and half of the

patients had the lesion surgically repaired [22,23].

4. High-risk injuries

Certain fracture patterns around the knee have a high

associated incidence of arterial injury. The popliteal artery is

tethered at the adductor hiatus in the medial distal thigh, and

again distal to the knee joint at the soleus arch. The tethered

artery becomes vulnerable to stretch, tear, or intimal damage

when the knee becomes displaced by dislocation or widely

displaced fracture. The clinician should have a high index ofduring recoil.

The tibial fractures that have a particular propensity for

association with arterial damage include the isolated medial

tibial plateau (Schatzker IV) fracture, as well as the

associated medial and lateral plateau fractures that dissociate

the articular surface from the tibial diaphysis (Schatzker VI).Fig. 5 Lateral radiograph of the femur showing segmental distalfemur fracture.

The medial plateau fracture can behave in a similar manner

as a knee dislocation. While the typical medial tibial frag-

ment is attached to the distal femur by the medial collateral

and cruciate ligaments, the shaft of the tibia displaces freely

with its lateral plateau and endangers the popliteal artery

(Fig. 2A and B). The combined medial and lateral plateau

fractures that dissociate the articular surface from the

diaphysis displace the shaft in a similar fashion, which

threatens the artery just proximal to or at the popliteal artery

trifurcation (Fig. 3A and B).

A purely ligamentous knee dislocation is associated with

a high risk of arterial injury, despite having no sharp fracture

fragments (Fig. 4A and C) [11,24,25]. This is possibly

because more energy is imparted to the soft tissues rather

than fracturing the tibia. Some authors have noted as high as

Fig. 7 (A) Anteroposterior and (B) lateral radiograph examplesof a bfloating knee.Q Note the ipsilateral femoral and tibial fractures.

ig. 8 Example of a gunshot wound to the lower extremity at thevel of the knee.

Arterial pressure index (API) 693Fig. 6 A, Lateral radiograph showing significantly displaced,comminuted distal femur fracture. B, Intraoperative photo demon-

strating the open wound.Flea 40% risk of popliteal injury associated with knee

dislocations [26-28].

wound, an arteriogram is warranted if the API is less than 0.9

because the possibility of multiple level injuries exists.

Another situation of concern regarding limb viability is

the mangled extremity (Fig. 9A and B). The mangled

extremity is not clearly defined with objective criteria and

represents the end of an injury spectrum that involves trauma

that destroys soft tissue and leaves limb survival in question.

Although the likelihood of arterial injury is high in these

patients, it may be overlooked because of the extensive soft

tissue and skeletal injuries.

5. Special considerations

The use of the API should be approached with certain

caveats in mind. It may not detect injuries to the profunda

femoris, profunda brachii, or peroneal arteries, as no direct

extension of flow is measured in the distal arteries [16].

B.A. Levy et al.694The widely displaced distal femur fracture yields a

similar threat to the vascular tree because the popliteal

artery is tethered to the femur at its transition from the

femoral artery in Hunters canal. The open femur fracture

(Fig. 5) and the distal segmental femur shaft fracture (Fig.

6A and B) imply greater energy and displacement. Clinical

judgment must be exercised in every case, as there may be

other suspicious fracture variants around the knee. However,

these are the injuries that should prompt an immediate API

examination.

The entity of the floating joint is defined as ipsilateral

long bone fractures occurring on both sides of a joint

(Fig. 7A and B). Other authors have included the ipsilateral

articular and long bone fracture in the definition of the

floating joint. These fractures are likely associated with

arterial injury for the reasons previously described [29].

Gunshot wounds are also associated with an increased

incidence (around 20%) of arterial injury (Fig. 8) [7,30]. It is

traditionally taught that gunshot wounds in proximity to

neurovascular structures ought to be screened. However, the

path of missiles is often not known and additional

precautions should be taken in these cases. It is important

for the clinician to screen such extremities given the quick

and inexpensive approach of the API. In the event hard signs

of vascular injury are present in the context of a gunshot

Fig. 9 A 41-year-old male pedestrian struck by train, sustaininga mangled lower leg with (A) significant soft tissue injury and (B)

comminuted, segmental distal femur fracture.< 0.90< 0.90

Duplex sonographyDuplex sonographyOperationOperation

(or arteriography)(or arteriography)Serial clinicalSerial clinicalexaminationexamination(-)(-)(+)(+)

> 0.90> 0.90

Doppler arterial pressure indexDoppler arterial pressure index

Fig. 10 Proposed treatment algorithm for vascular assessment inlower extremity trauma.6. Conclusion

The API has fulfilled the requirements of a useful

screening tool, is both sensitive and specific with an out-

standing negative predictive value, and is reproducible, non-

invasive, and inexpensive. The clinician should approach

the patient who has a high-risk vascular injury with a clear

diagnostic algorithm (Fig. 10).

In addition to patients with one of the 4 hard signs of

vascular arterial injury, a patients API should dictate the

Arterial hemorrhage, distal ischemia,Arterial hemorrhage, distal ischemia,shotgun injuryshotgun injury

YesYes NoNoLesions that do not decrease blood flow (eg, a minor intimal

flap) may not be detected [21]. Certain clinical situations

may preclude cuff placement, such as massive injury around

the wrist or ankle or the presence of splints on the injured

site. Traction ought to be applied to the extremity and gross

limb alignment restored before measuring the API to avoid

false-negative results. Finally, in a case where determination

of the pulse by physical exam may be inadequate or

compromised (hypovolemic shock or isolated venous

injury), the API should be used with caution.

next step. If the API is greater than 0.9, the patient may be

followed clinically without further workup. If the API is less

than 0.9, an arteriogram or duplex ultrasound should be

completed and will dictate the final plan of action. It is

impossible to define every possible clinical scenario that

could manifest arterial trauma. However, if the clinician

bears these red flags in mind, the vast majority of vascular

problems are likely to be detected.

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Screening for extermity arterial injury with the arterial injury with the arterial pressure indexIntroductionScreening for arterial injuryThe APIHigh-risk injuriesSpecial considerationsConclusionReferences