Chapter 18
Penetrating Trauma to the Extremities and Vascular Injuries

Christopher R. Carpenter¹ and Ali S. Raja²

¹ Department of Emergency Medicine, Washington University School of Medicine, St. Louis, MO, USA

² Department of Emergency Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA

Background

Firearms account for over half of penetrating injuries to the extremities in the United States.¹ In contrast, blunt mechanisms and penetrating knife wounds are more common in Europe and Asia for extremity vascular trauma.^2,3 Penetrating vascular injuries across the United States were associated with 3.8% mortality rate and 1.3% of patients had amputations.⁴ Missed vascular injuries delay time to definitive operative or nonoperative management, but occult injuries are common. In fact, trauma guidelines sometimes differ in providing diagnostic evaluation recommendations. For example, the Eastern Association for the Surgery of Trauma (EAST) practice management guideline⁵ and Western Trauma Association (WTA) position papers^6,7 provide slightly different definitions of “hard” and “soft” signs (Table 18.1).⁸ The presence of hard signs indicates the need for immediate exploration in the operating room, but vascular injuries can be present in the absence of hard signs. Specifically, the presence of peripheral pulses cannot exclude arterial injury.⁹

Table 18.1 Differing definitions of hard and soft signs between organizations

Guideline	Hard sign	Soft sign
EAST	Bruit	History of arterial bleeding
	Expanding hematoma	Neurologic deficit
	Pulsatile bleeding	Nonexpanding hematoma
	Pulse deficit	Wound proximity to artery
	Thrill	Wound proximity to artery
WTA	Bruit	History of arterial bleeding
	Expanding hematoma	Neurologic deficit
	External bleeding	Small nonpulsatile hematoma
	Pain	Wound proximity to artery
	Pallor
	Paralysis
	Paresthesia
	Pulselessness
	Thrill

Trauma care of extremity vascular injuries has evolved over the last 60 years. Rather than resulting in amputations, the majority of extremity vascular injuries can now be repaired. As operative repair has improved, the role of the diagnostic evaluation has also evolved. In addition to evaluating hard and soft signs, the ankle–brachial index (ABI) is used to identify patients at risk for vascular injury.⁹ Since traditional angiography is invasive and carries risks that outweigh its benefits in routine use, noninvasive diagnostic techniques have emerged as accurate alternatives to angiography or surgical exploration. CT angiography (CTA) has replaced Doppler ultrasonography as the imaging modality of choice to identify the presence or absence of an extremity vascular injury.⁹ Many centers have developed diagnostic algorithms that utilize all these diagnostic modalities to avoid invasive angiography and surgical exploration while still maximizing limb salvage and patient outcomes. For this chapter, we reviewed studies of civilian penetrating extremity trauma, as military injuries typically involve much higher energy trauma than typical civilian injuries caused by knives and handguns.

Table 18.2 Diagnostic characteristics of hard signs

Source: Data from [7–11,13].

Author	N	Prevalence (%)	Sensitivity (%)	Specificity (%)	LR+	LR−
Schwartz et al.¹¹	469	16	49	83	3	0.6
Gonzalez (1999)	489	10	92	95	19	0.08
Inaba et al.¹²	212	16	60	100	210	0.4

Note: LR+ = positive likelihood ratio; and LR− = negative likelihood ratio.

Clinical question

What clinical signs and symptoms reliably predict a penetrating vascular injury?

For emergency medicine, the physical examination remains the mainstay of the evaluation of penetrating extremity wounds, so as not to indiscriminately obtain vascular imaging on every patient with the accompanying risks of medical radiation exposure and healthcare costs.¹⁰ Soft signs should not be used to rule in or rule out the possibility of penetrating vascular injury, as they do not add diagnostic value. Although the definitions of hard signs varied between studies, and individual study designs were at risk for spectrum bias, incorporation bias, and differential verification bias, one emergency department‐based diagnostic meta‐analysis summarizes the accuracy of hard signs (Table 18.2).^8,13 Notably, high heterogeneity in pooled estimates of LR+ (I² = 96.5%) and LR− (I² = 92.6%) precluded meta‐analysis. This heterogeneity probably reflects between‐study differences in defining and evaluating hard signs. For example, Schwartz et al. included neurologic deficit as a hard sign but Gonzalez labeled that a soft sign.^11,14 Bruit represented a hard sign for Gonzalez and Inaba, but a soft sign by Schwartz.^11,12,14 None of these studies reported intra‐ or inter‐rater reliability of these physical exam findings, so their reproducibility remains unknown.

Clinical question

Can ABI be used to rule out penetrating vascular injury?

The ABI is a test to compare arterial pressures and is used for both acute and chronic vascular evaluation. The ABI is the ratio between systolic blood pressures measured distal to a penetrating lower extremity injury and the systolic blood pressure measured on an uninjured and nondiseased upper extremity. In contrast, the arterial pressure index (API) is the ratio between systolic blood pressures measured distal to a penetrating injury in one extremity and measured at the same location on the contralateral uninjured extremity. The ABI and API are valid for injuries distal to the “shoulder” and “groin.” These are inexact terms, so the more proximal the injury, the less valid the use of these indices becomes. Generally, pressures are obtained using a Doppler vascular probe and a blood pressure cuff. The injured limb’s pressure is divided by the noninjured limb’s pressure, and the resulting proportion is the ABI or API. One emergency department‐based diagnostic meta‐analysis summarizes the accuracy of the ABI (Table 18.3).⁸