- Email: [email protected]
Screening for extermity arterial injury with the arterial injury with the arterial pressure index
American Journal of Emergency Medicine (2005) 23, 689 – 695
www.elsevier.com/locate/ajem
Diagnostics
Screening for extermity arterial injury with the arterial pressure index Bruce A. Levy MDa,1, Michael P. Zlowodzki MDb,2, Matt Graves MDc,3, Peter A. Cole MDd,* a
Sports and Knee Injuries, Regions Hospital, University of Minnesota, St Paul, MN 55101, USA Department of Orthopaedic Surgery, Regions Hospital, University of Minnesota, St Paul, MN 55101, USA c Department of Orthopaedic Surgery and Rehabilitation, University of Mississippi Medical Center, Jackson, MS 39216-4505, USA d Orthopaedic Trauma, Regions Hospital, University of Minnesota, St Paul, MN 55101, USA b
Received 1 December 2004; accepted 22 December 2004
Abstract Certain extremity injuries presenting to the ED or Trauma Unit warrant increased suspicion for 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 mangled 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 this 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].
T Corresponding author. Tel.: +1 651 254 0929; fax: +1 651 254 1519. E-mail addresses: [email protected] (M.P. Zlowodzki)8 [email protected] (M. Graves), [email protected] (P.A. Cole). 1 Tel.: +1 651 254 1515; fax: +1 651 254 3247. 2 Tel.: +1 651 254 1513; fax: +1 651 254 1519. 3 Tel.: +1 601 984 6525. 0735-6757/$ – see front matter D 2005 Published by Elsevier Inc. doi:10.1016/j.ajem.2004.12.013
690
B.A. Levy et al.
The purpose of this article is to present an evidence-based algorithm for patients who present with either arterial injury or a high-risk of arterial injury. A diagnostic algorithm will be presented, and the rationale for diagnostic interventions will be discussed in the context of current medical literature. D 2005 Published by Elsevier Inc.
1. Introduction
2. Screening for arterial injury
The 4 bhard signsQ of extremity vascular injury include pulsatile 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 at the 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 dislocations, 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]. Because 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 evaluation for possible arterial injury from extremity trauma. A safe, efficient, cost-effective, and evidence-based algorithm is required.
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 test’s 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 accompanied high-velocity missile damage [12]. Such an approach did not translate sensibly to low-energy civilian injuries, so the
Fig. 1 Example of the placement of the blood pressure cuffs on the extremities for assessment of API.
Arterial pressure index (API)
691 investigated as a screening tool for clinically significant arterial compromise [16,21,22]. To conduct an API examination, 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 ¼
Fig. 2 (A) Anteroposterior (AP) and (B) lateral radiographs demonstrating 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.
Doppler systolic arterial pressure in injured limb Doppler 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
mandatory operative approach was abandoned based on invasiveness and high negative results [4,6,13]. Arteriography as a screening tool (exclusion arteriography) 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 [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 interpreterdependent 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 been
Fig. 3 (A) Sagittal and (B) coronal computed tomography scan showing 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.
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Fig. 4 A, Anteroposterior radiograph of the knee showing complete knee dislocation. B and C, Angiography shows postreduction AP view with complete occlusion of the popliteal artery.
limited 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 costeffectiveness of the API was also examined and showed that over the 6O- month period, exclusion arteriograms were reduced from 14% to 5.2% of all contrast studies and resulted in a net savings of $65 175 [21]. Before this study, the API was primarily used on patients with penetrating injuries. Orthopedists and other practitioners 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 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].
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 during 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).
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 of
Fig. 5 Lateral radiograph of the femur showing segmental distal femur fracture.
Arterial pressure index (API)
693
The medial plateau fracture can behave in a similar manner as a knee dislocation. While the typical medial tibial fragment 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
Fig. 7 (A) Anteroposterior and (B) lateral radiograph examples of a bfloating knee.Q Note the ipsilateral femoral and tibial fractures.
than fracturing the tibia. Some authors have noted as high as a 40% risk of popliteal injury associated with knee dislocations [26-28].
Fig. 6 A, Lateral radiograph showing significantly displaced, comminuted distal femur fracture. B, Intraoperative photo demonstrating the open wound.
Fig. 8 Example of a gunshot wound to the lower extremity at the level of the knee.
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B.A. Levy et al. 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
Fig. 9 A 41-year-old male pedestrian struck by train, sustaining a mangled lower leg with (A) significant soft tissue injury and (B) comminuted, segmental distal femur fracture.
The 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 Hunter’s 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
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]. Lesions 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.
6. Conclusion The API has fulfilled the requirements of a useful screening tool, is both sensitive and specific with an outstanding negative predictive value, and is reproducible, noninvasive, 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 patient’s API should dictate the
Arterial hemorrhage, distal ischemia, shotgun injury Yes
No Doppler arterial pressure index < 0.90
> 0.90
Duplex sonography Operation (or arteriography)
(+)
(-)
Serial clinical examination
Fig. 10 Proposed treatment algorithm for vascular assessment in lower extremity trauma.
Arterial pressure index (API) 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.
References [1] Anderson RJ, Hobson II RW, Lee BC, et al. Reduced dependency on arteriography for penetrating extremity trauma: influence of wound location and noninvasive vascular studies. J Trauma 1990; 30(9):1059 - 63 [discussion 1055-63]. [2] Anderson RJ, Hobson II RW, Padberg Jr FT, et al. Penetrating extremity trauma: identification of patients at high-risk requiring arteriography. J Vasc Surg 1990;11(4):544 - 8. [3] Snyder III WH, Thal ER, Bridges RA, et al. The validity of normal arteriography in penetrating trauma. Arch Surg 1978;113(4):424 - 6. [4] Turcotte JK, Towne JB, Bernhard VM. Is arteriography necessary in the management of vascular trauma of the extremities? Surgery 1978; 84(4):557 - 62. [5] Perry MO, Thal ER, Shires GT. Management of arterial injuries. Ann Surg 1971;173(3):403 - 8. [6] Rose SC, Moore EE. Trauma angiography: the use of clinical findings to improve patient selection and case preparation. J Trauma 1988;28(2): 240 - 5. [7] Weaver FA, Yellin AE, Bauer M, et al. Is arterial proximity a valid indication for arteriography in penetrating extremity trauma? A prospective analysis. Arch Surg 1990;125(10):1256 - 60. [8] Menzoian JO, Doyle JE, LoGerfo FW, et al. Evaluation and management of vascular injuries of the extremities. Arch Surg 1983; 118(1):93 - 5. [9] Miller H, Welch S. Quantitative studies on the time factor in arterial injuries. Ann Surg 1949;130:428 - 38. [10] Snyder III WH. Vascular injuries near the knee: an updated series and overview of the problem. Surgery 1982;91(5):502 - 6. [11] Kendall RW, Taylor DC, Salvian AJ, et al. The role of arteriography in assessing vascular injuries associated with dislocations of the knee. J Trauma 1993;35(6):875 - 8. [12] Fitchett VH, Pomerantz M, Butsch DW, et al. Penetrating wounds of the neck. A military and civilian experience. Arch Surg 1969;99(3): 307 - 14. [13] Sirinek KR, Levine BA, Gaskill III HV, et al. Reassessment of the role of routine operative exploration in vascular trauma. J Trauma 1981; 21(5):339 - 44.
695 [14] Reid JD, Weigelt JA, Thal ER, et al. Assessment of proximity of a wound to major vascular structures as an indication for arteriography. Arch Surg 1988;123(8):942 - 6. [15] Applebaum R, Yellin AE, Weaver FA, et al. Role of routine arteriography in blunt lower-extremity trauma. Am J Surg 1990;160(2):221 - 4 [discussion 224-5]. [16] Lynch K, Johansen K. Can Doppler pressure measurement replace bexclusionQ arteriography in the diagnosis of occult extremity arterial trauma? Ann Surg 1991;214(6):737 - 41. [17] Francis III H, Thal ER, Weigelt JA, et al. Vascular proximity: is it a valid indication for arteriography in asymptomatic patients? J Trauma 1991;31(4):512 - 4. [18] Hessel SJ, Adams DF, Abrams HL. Complications of angiography. Radiology 1981;138(2):273 - 81. [19] Meissner M, Paun M, Johansen K. Duplex scanning for arterial trauma. Am J Surg 1991;161(5):552 - 5. [20] Panetta TF, Hunt JP, Buechter KJ, et al. Duplex ultrasonography versus arteriography in the diagnosis of arterial injury: an experimental study. J Trauma 1992;33(4):627 - 35 [discussion 626-35]. [21] Johansen K, Lynch K, Paun M, et al. Non-invasive vascular tests reliably exclude occult arterial trauma in injured extremities. J Trauma 1991;31(4):515 - 9 [discussion 519-22]. [22] Mills WJ, Barei DP, McNair P. The value of the ankle-brachial index for diagnosing arterial injury after knee dislocation: a prospective study. J Trauma 2004;56(6):1261 - 5. [23] Bunt TJ, Malone JM, Moody M, et al. Frequency of vascular injury with blunt trauma-induced extremity injury. Am J Surg 1990;160(2): 226 - 8 [24] Dennis JW, Frykberg ER, Veldenz HC, et al. Validation of nonoperative management of occult vascular injuries and accuracy of physical examination alone in penetrating extremity trauma: 5- to 10-year follow-up. J Trauma 1998;44(2):243 - 52 [discussion 242-3]. [25] Miranda FE, Dennis JW, Veldenz HC, et al. Confirmation of the safety and accuracy of physical examination in the evaluation of knee dislocation for injury of the popliteal artery: a prospective study. J Trauma 2002;52(2):247 - 51 [discussion 242-51]. [26] Jones RE, Smith EC, Bone GE. Vascular and orthopedic complications of knee dislocation. Surg Gynecol Obstet 1979; 149(4):554 - 8. [27] Green NE, Allen BL. Vascular injuries associated with dislocation of the knee. J Bone Joint Surg Am 1977;59(2):236 - 9. [28] Shields L, Mital M, Cave EF. Complete dislocation of the knee: experience at the Massachusetts General Hospital. J Trauma 1969;9(3): 192 - 215. [29] Lundy DW, Johnson KD. bFloating kneeQ injuries: ipsilateral fractures of the femur and tibia. J Am Acad Orthop Surg 2001; 9(4):238 - 45. [30] Walker ML, Poindexter Jr JM, Stovall I. Principles of management of shotgun wounds. Surg Gynecol Obstet 1990;170(2):97 - 105.
www.elsevier.com/locate/ajem
Diagnostics
Screening for extermity arterial injury with the arterial pressure index Bruce A. Levy MDa,1, Michael P. Zlowodzki MDb,2, Matt Graves MDc,3, Peter A. Cole MDd,* a
Sports and Knee Injuries, Regions Hospital, University of Minnesota, St Paul, MN 55101, USA Department of Orthopaedic Surgery, Regions Hospital, University of Minnesota, St Paul, MN 55101, USA c Department of Orthopaedic Surgery and Rehabilitation, University of Mississippi Medical Center, Jackson, MS 39216-4505, USA d Orthopaedic Trauma, Regions Hospital, University of Minnesota, St Paul, MN 55101, USA b
Received 1 December 2004; accepted 22 December 2004
Abstract Certain extremity injuries presenting to the ED or Trauma Unit warrant increased suspicion for 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 mangled 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 this 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].
T Corresponding author. Tel.: +1 651 254 0929; fax: +1 651 254 1519. E-mail addresses: [email protected] (M.P. Zlowodzki)8 [email protected] (M. Graves), [email protected] (P.A. Cole). 1 Tel.: +1 651 254 1515; fax: +1 651 254 3247. 2 Tel.: +1 651 254 1513; fax: +1 651 254 1519. 3 Tel.: +1 601 984 6525. 0735-6757/$ – see front matter D 2005 Published by Elsevier Inc. doi:10.1016/j.ajem.2004.12.013
690
B.A. Levy et al.
The purpose of this article is to present an evidence-based algorithm for patients who present with either arterial injury or a high-risk of arterial injury. A diagnostic algorithm will be presented, and the rationale for diagnostic interventions will be discussed in the context of current medical literature. D 2005 Published by Elsevier Inc.
1. Introduction
2. Screening for arterial injury
The 4 bhard signsQ of extremity vascular injury include pulsatile 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 at the 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 dislocations, 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]. Because 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 evaluation for possible arterial injury from extremity trauma. A safe, efficient, cost-effective, and evidence-based algorithm is required.
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 test’s 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 accompanied high-velocity missile damage [12]. Such an approach did not translate sensibly to low-energy civilian injuries, so the
Fig. 1 Example of the placement of the blood pressure cuffs on the extremities for assessment of API.
Arterial pressure index (API)
691 investigated as a screening tool for clinically significant arterial compromise [16,21,22]. To conduct an API examination, 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 ¼
Fig. 2 (A) Anteroposterior (AP) and (B) lateral radiographs demonstrating 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.
Doppler systolic arterial pressure in injured limb Doppler 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
mandatory operative approach was abandoned based on invasiveness and high negative results [4,6,13]. Arteriography as a screening tool (exclusion arteriography) 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 [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 interpreterdependent 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 been
Fig. 3 (A) Sagittal and (B) coronal computed tomography scan showing 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.
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B.A. Levy et al.
Fig. 4 A, Anteroposterior radiograph of the knee showing complete knee dislocation. B and C, Angiography shows postreduction AP view with complete occlusion of the popliteal artery.
limited 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 costeffectiveness of the API was also examined and showed that over the 6O- month period, exclusion arteriograms were reduced from 14% to 5.2% of all contrast studies and resulted in a net savings of $65 175 [21]. Before this study, the API was primarily used on patients with penetrating injuries. Orthopedists and other practitioners 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 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].
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 during 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).
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 of
Fig. 5 Lateral radiograph of the femur showing segmental distal femur fracture.
Arterial pressure index (API)
693
The medial plateau fracture can behave in a similar manner as a knee dislocation. While the typical medial tibial fragment 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
Fig. 7 (A) Anteroposterior and (B) lateral radiograph examples of a bfloating knee.Q Note the ipsilateral femoral and tibial fractures.
than fracturing the tibia. Some authors have noted as high as a 40% risk of popliteal injury associated with knee dislocations [26-28].
Fig. 6 A, Lateral radiograph showing significantly displaced, comminuted distal femur fracture. B, Intraoperative photo demonstrating the open wound.
Fig. 8 Example of a gunshot wound to the lower extremity at the level of the knee.
694
B.A. Levy et al. 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
Fig. 9 A 41-year-old male pedestrian struck by train, sustaining a mangled lower leg with (A) significant soft tissue injury and (B) comminuted, segmental distal femur fracture.
The 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 Hunter’s 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
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]. Lesions 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.
6. Conclusion The API has fulfilled the requirements of a useful screening tool, is both sensitive and specific with an outstanding negative predictive value, and is reproducible, noninvasive, 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 patient’s API should dictate the
Arterial hemorrhage, distal ischemia, shotgun injury Yes
No Doppler arterial pressure index < 0.90
> 0.90
Duplex sonography Operation (or arteriography)
(+)
(-)
Serial clinical examination
Fig. 10 Proposed treatment algorithm for vascular assessment in lower extremity trauma.
Arterial pressure index (API) 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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695 [14] Reid JD, Weigelt JA, Thal ER, et al. Assessment of proximity of a wound to major vascular structures as an indication for arteriography. Arch Surg 1988;123(8):942 - 6. [15] Applebaum R, Yellin AE, Weaver FA, et al. Role of routine arteriography in blunt lower-extremity trauma. Am J Surg 1990;160(2):221 - 4 [discussion 224-5]. [16] Lynch K, Johansen K. Can Doppler pressure measurement replace bexclusionQ arteriography in the diagnosis of occult extremity arterial trauma? Ann Surg 1991;214(6):737 - 41. [17] Francis III H, Thal ER, Weigelt JA, et al. Vascular proximity: is it a valid indication for arteriography in asymptomatic patients? J Trauma 1991;31(4):512 - 4. [18] Hessel SJ, Adams DF, Abrams HL. Complications of angiography. Radiology 1981;138(2):273 - 81. [19] Meissner M, Paun M, Johansen K. Duplex scanning for arterial trauma. Am J Surg 1991;161(5):552 - 5. [20] Panetta TF, Hunt JP, Buechter KJ, et al. Duplex ultrasonography versus arteriography in the diagnosis of arterial injury: an experimental study. J Trauma 1992;33(4):627 - 35 [discussion 626-35]. [21] Johansen K, Lynch K, Paun M, et al. Non-invasive vascular tests reliably exclude occult arterial trauma in injured extremities. J Trauma 1991;31(4):515 - 9 [discussion 519-22]. [22] Mills WJ, Barei DP, McNair P. The value of the ankle-brachial index for diagnosing arterial injury after knee dislocation: a prospective study. J Trauma 2004;56(6):1261 - 5. [23] Bunt TJ, Malone JM, Moody M, et al. Frequency of vascular injury with blunt trauma-induced extremity injury. Am J Surg 1990;160(2): 226 - 8 [24] Dennis JW, Frykberg ER, Veldenz HC, et al. Validation of nonoperative management of occult vascular injuries and accuracy of physical examination alone in penetrating extremity trauma: 5- to 10-year follow-up. J Trauma 1998;44(2):243 - 52 [discussion 242-3]. [25] Miranda FE, Dennis JW, Veldenz HC, et al. Confirmation of the safety and accuracy of physical examination in the evaluation of knee dislocation for injury of the popliteal artery: a prospective study. J Trauma 2002;52(2):247 - 51 [discussion 242-51]. [26] Jones RE, Smith EC, Bone GE. Vascular and orthopedic complications of knee dislocation. Surg Gynecol Obstet 1979; 149(4):554 - 8. [27] Green NE, Allen BL. Vascular injuries associated with dislocation of the knee. J Bone Joint Surg Am 1977;59(2):236 - 9. [28] Shields L, Mital M, Cave EF. Complete dislocation of the knee: experience at the Massachusetts General Hospital. J Trauma 1969;9(3): 192 - 215. [29] Lundy DW, Johnson KD. bFloating kneeQ injuries: ipsilateral fractures of the femur and tibia. J Am Acad Orthop Surg 2001; 9(4):238 - 45. [30] Walker ML, Poindexter Jr JM, Stovall I. Principles of management of shotgun wounds. Surg Gynecol Obstet 1990;170(2):97 - 105.