Vascular Hand Injury 

The upper extremity is defined as the anatomic region distal to the deltoid muscle. This area is composed of the arm, anatomic structures from the shoulder to the elbow; the forearm, anatomic structures from the elbow to the wrist; and the hand, anatomic structures distal to the wrist.

Vascular trauma of the upper extremity has become increasingly common and can be subcategorized into penetrating trauma, blunt force trauma, and iatrogenic injuries. Vascular trauma can cause a high degree of morbidity with severe consequences on function.^[1] Successful management with good outcomes depends on early diagnosis and prompt intervention. The surgeon must be knowledgeable of the relevant vascular anatomy and of the surgical techniques available to treat upper extremity vascular injuries. In addition, the surgeon must be able to intervene in a systematic approach garnered by a high index of suspicion based upon the mechanism of injury.^[2]

Early methods for treating bleeding vessels included the use of chemical styptic, cauterization, and ligation. Ligature of major arteries was the mainstay treatment during extremity amputation throughout the 18^th century.

The first documented arterial repair of the brachial artery is credited to Hallowell in 1762, acting upon a suggestion by his colleague Richard Lambert in 1759. The method of repair involved the elevation of the edges of the lacerated artery with a half-inch steel pin followed by a figure-of-eight suture about the pin to coapt the arterial walls. The pin and suture were eventually extruded, leaving a viable extremity with a palpable pulse at the wrist. Despite the documented success of this lateral arteriorrhaphy, the procedure fell out of favor for more than a century. It was not until 1886 that Postempski reported a second successful lateral arteriorrhaphy. By 1910, more than 100 cases of lateral arteriorrhaphy and 46 repairs by using end-to-end anastomosis and vein grafts were reported.^[3]

Treatment of upper extremity vascular injuries has evolved considerably during wartime conflict. During the US Civil War, options for repair of upper extremity vascular injury failed to exist, resulting in amputation of the affected extremity(s). The mortality rate for upper extremity amputation ranged from 10-40% during that conflict.^[4]

Interestingly, ligation of major arteries would remain the mainstay of treatment for upper extremity vascular injuries until the Korean War. Rapid advances in vascular surgery techniques in the 1950s combined with aggressive antibiotic treatment revolutionized the management of wartime vascular injuries. During the Korean War, the overall amputation rate was lowered to 13% compared with 49% in World War II. In Vietnam, the overall extremity amputation rate remained at 13%, but approximately 5% for associated brachial artery injuries. Only 2% of brachial artery injuries required ligation; however, nearly 60% of radial artery and 75% of ulnar artery injuries were ligated during the Vietnam conflict.^[5]

In the past several decades, most surgical experience has come from the civilian population. The incidence of vascular injuries has risen due to the increased rates of automobile accidents, firearm-related urban violence, and the expansion of interventional cardiovascular diagnostic and therapeutic procedures.^[6] One modern study of upper extremity vascular injury reported a primary amputation rate of 5.7% and a secondary amputation rate (amputation following primary revascularization procedure) of 8.2%.^[7] More recent wartime data collected during the Iraqi conflict (Operation Iraqi Freedom) demonstrate an upper extremity amputation rate of 9.3%.^[8] This increased rate of upper extremity amputation may reflect the devastating impact of improvised explosive devices (IEDs) rather than changes in surgical techniques and treatment methods.

Using data from The Joint Theater Trauma Registry, one study evaluated the epidemiology of vascular injury in the wars of Iraq and Afghanistan by identifying the categorization of anatomic patterns, management of casualties, and mechanism of injury, including explosive, gunshot, and other injuries. The study found that the rate of vascular injury in modern combat is 5 times higher than in previous wars and varies according to operational tempo, mechanism of injury, and theater of war. Newer methods of reconstruction, including endovascular surgery, are now applied to nearly half the vascular injuries and should be a focus of training for combat surgery.^[9]

Frequency

Upper extremity injuries constitute approximately 40% of all peripheral vascular injuries, with more than 67% resulting from penetrating trauma.^{[10, 11]} Injuries to the brachial artery are most commonly reported; they account for 40-55% of all upper extremity arterial injuries. Injuries to the axillary artery represent 6-23% of upper extremity arterial injuries, and radial and ulnar arterial injuries make up 4-36% of upper extremity arterial injuries.^{[7, 10, 11, 12, 13]}

Modern series continue to demonstrate low mortality rates and upper extremity amputation rates of 0.8-2% for civilian penetrating trauma and 6-24% for civilian blunt trauma.^[14] The mortality rate of patients with upper extremity vascular trauma is primarily related to other associated severe injuries (eg, closed-head injuries, intra-abdominal trauma). Morbidity related to upper extremity vascular injuries frequently correlates with associated injuries, such as peripheral nerve injury and/or long bone fracture.

The most common cause of upper extremity vascular injury is penetrating trauma secondary to gunshot wounds, stab wounds, and lacerations from broken glass. However, iatrogenic trauma secondary to the widespread use of diagnostic and therapeutic intravascular techniques has also contributed to an increased incidence of upper extremity vascular injury. Although vascular injury following blunt trauma of the upper extremity is less common, it deserves emphasis because it can be easily overlooked unless the clinician maintains a high index of suspicion. This type of injury is more commonly seen after automobile accidents and athletic injuries, most of which result in intimal tears and subsequent thrombosis of the vessels.

Injuries to the axillary artery are occasionally associated with proximal humeral fractures and anterior dislocations of the shoulder. These injuries are also associated with athletes who perform repetitive, high-stress, overhead arm motions.^[15] Supracondylar fractures of the humerus or elbow dislocations should raise the suspicion for a possible brachial artery injury. Hypothenar hammer syndrome results from repetitive palmar trauma leading to injury of the ulnar artery as it passes around the hook of the hamate bone in the wrist (see image below for artery anatomy).^[16]

Please see Indications below.

A thorough history and careful physical examination for signs of vascular injury are the first and most important steps in making the diagnosis. Fractures and dislocations should be reduced before thorough examination of the upper extremity. Clinical signs for the prediction of an arterial extremity injury include both "hard" and "soft" signs.^[17]

Hard signs include the following:

• Active or pulsatile hemorrhage
• Pulsatile or expanding hematoma
• Thrill or bruit (suggesting an AV fistula)
• Evidence of ischemia (pallor, paresthesia, paralysis, pain, and poikilothermia)
• Diminished or absent pulses

These obvious signs almost always indicate an underlying arterial injury and are indications for immediate surgical intervention.

Soft signs include the following:

• Moderate hemorrhage occurring at the scene of the injury
• Stable and nonpulsatile hematoma
• Proximity of a wound to a major vessel
• Peripheral neurological deficit
• Asymmetric extremity blood pressures
• Presence of shock/hypotension
• Associated fracture or dislocation

These soft, or equivocal, signs may indicate the need for further evaluation with Doppler studies, CT angiography, contrast arteriography, or surgical exploration to confirm or exclude vascular injury.

Note that a palpable radial pulse does not exclude a proximal vascular injury. The rich collateral networks around the shoulder and elbow in combination with the paired major vessels at the forearm may result in normal physical findings though an underlying arterial injury may be present.

In the hand, the collateral circulation should be objectively assessed by performing a modified Allen's test.^[18] The modified Allen's test is performed by applying firm occlusive pressure simultaneously to both the ulnar and radial arteries at the level of the patient's wrist. The patient is asked to clench his/her fist several times during this occlusive period until the palmar skin blanches. The patient is then instructed to unclench the fist avoiding wrist and finger hyperextension (which can lead to falsely abnormal results).^[19]

At this point, the ulnar artery occlusive pressure is released while maintaining occlusive pressure on the radial artery. The time required for capillary refill of the palmar skin is noted. The test is then repeated releasing the radial arterial occlusion while maintaining occlusion of the ulnar artery (the inverse modified Allen's test). Return of color to the palmar skin should occur in 5-10 seconds for the test to be considered negative (implying an intact palmar arch).

Based upon this subjective and highly operator-dependent technique, up to 27% of the general population demonstrates a discontinuous palmar arch where direct communication between the radial and ulnar arteries is absent.^[20] With the advent of Doppler ultrasonography, diagnostic accuracy of the modified Allen's test has come into question. Jarvis et al found the diagnostic accuracy of the modified Allen's test, compared with ultrasonography, was only 80%, with a sensitivity of 76% and a specificity of 82% occurring with a 5-second recovery time.^[21]

Glavin and Jones compared the modified Allen's test with Doppler ultrasonography in 75 patients and found that 80% of all abnormal modified Allen's test results in their study were incorrect.^[22] These results would suggest that patients with an abnormal or positive modified Allen's test result should have more objective studies performed to determine the true anatomy of the superficial and deep arterial system in the hand. Despite this, no standard criteria for Doppler ultrasonographic findings that define abnormal hand collateral perfusion are established.

In an effort to address the inadequacies and shortcomings of the modified Allen's test, evaluation of the ulno-palmar arterial arches with pulse oximetry and plethysmography has been described. In a cohort of 1010 patients, Barbeau et al found 1.5% of patients with unsuitable anatomy for transradial cardiac catheterization.^[23] Arterial patency can be assessed objectively by monitoring the oxygen saturation and waveform while performing the modified Allen's test. Obvious advantages to this technique are that it does not rely upon the subjective assessment of color change in the palm, it can easily be performed in the operating room, and it can be performed in sedated and obtunded patients without difficulty. Disadvantages to this technique include the theoretical concern that normal pulse oximetry saturation may not ensure adequate tissue perfusion^[24] and that plethysmography suffers from the inability to quantify blood flow.^[25]

The arterial pressure index (API) or arm-arm pressure index (A-A index) measured with a hand-held Doppler unit is a useful adjunct to the physical examination. The systolic pressure in the noninjured upper extremity (denominator) is compared with the systolic pressure in the injured upper extremity (numerator). Johansen and colleagues found that an API of less than 0.90 had 95% sensitivity and 97% specificity for occult arterial injury.^[26] An API of greater than 0.90 had a negative predictive value of 99%.^[26]

Vascular injuries of the upper extremity are defined as those occurring distal to the lateral border of the first rib. The axillary artery is a continuation of the subclavian artery and extends from the lateral margin of the first rib to the lateral margin of the teres major muscle. It is divided into 3 segments by the pectoralis minor muscle and gives off 6 arterial branches that contribute to the rich collateral circulation around the shoulder girdle (see image below). These branches are the superior thoracic, thoracoacromial, lateral thoracic, subscapular, and anterior and posterior circumflex arteries. The close proximity of the axillary artery to the axillary vein and brachial plexus provides the anatomic basis for the development of arteriovenous fistulas and high incidence of concomitant nerve injuries.

The brachial artery is a continuation of the axillary artery. It begins at the lateral margin of the teres major muscle and terminates one inch below the elbow crease at its bifurcation. The profunda brachii, superior ulnar collateral, and inferior ulnar collaterals are the main arterial branches of the brachial artery. These vessels provide important collateral circulation around the elbow (see image above). In the distal aspect, the brachial artery lies next to the median nerve. The relatively superficial and exposed location of the vessel makes it highly susceptible to injury.

Within the forearm the brachial artery bifurcates into the radial and ulnar arteries. The main arterial branches, which contribute to the collateral network around the elbow, include the radial recurrent a. originating off the radial artery, the ulnar recurrent a. and the interosseous a. originating from the ulnar artery.

The radial and ulnar arteries course through the forearm and terminate as the deep and superficial palmar arches, respectively. The ulnar artery is the larger of the two vessels and the major source of blood flow to the digits. As mentioned previously, the superficial arch is incomplete in approximately 20% of patients.