Surgical Damage Control and Temporary Vascular Shunts

Introduction

Since the turn of the century, there have been major changes in the management of the severely injured patient. Perhaps most notable is the adoption of damage control or staged procedures. Stone and colleagues provided the landmark description of a staged operation in 1983. With intent to limit the physiologic burden on an already threatened patient, they demonstrated a survival advantage in a series of 17 patients. Later coined by Rotondo et al. as “damage control surgery,” this concept of limiting the “bloody vicious cycle” of hypothermia, acidosis, and coagulopathy has been embraced in nearly every major trauma center with reproducible results. One of the tenets of staged laparotomy as described by Stone and colleagues was the attention to control and repair of blood vessel injuries. Hemorrhage (and subsequently, hemorrhagic shock) is perhaps the most significant factor contributing to the triad of coagulopathic bleeding. Incidentally, the management of injured blood vessels in a severely injured patient is often arduous, technically demanding, and time-consuming, all of which can force vessel ligation out of desperation. This chapter provides a review of a technique that offers a viable alternative to ligation and adheres to the mantra of damage control, namely the use of temporary intravascular shunts.

Temporary shunts have many benefits in the multiply injured patient. Not only do they allow for reperfusion and/or venous decompression across the injured vessel, but they also afford time to transport a patient to a higher level of care or to manage concomitant life-threatening injuries. In this context, “extra time” means that flow is restored across the injured artery and/or vein through the shunt while resuscitation, orthopedic fixation, cranial decompression or other lifesaving procedures are performed. In addition to gaining time to treat the patient, temporary shunts also limit the ischemic insult that results from vascular ligation, which can also negatively impact the physiology of the patient.

Historical Use of Intravascular Shunts

The concept of an implantable prosthetic conduit has a long history, with first descriptions in World War I by Tuffier and Makins. These paraffin-lined silver tubes were proposed for the perceived advantages of sutureless technique and initially meant for permanent placement. The general goal was not long-term patency of the conduit, but rather a temporary means of perfusion that would promote collateral formation as the tube slowly occluded. In 1932, Blakemore and Lord introduced use of a new composite alloy called Vitallium (composed of cobalt, chromium, and molybdenum). Initially, the Vitallium tube was internally lined with vein graft but was soon followed by a two-tube method with interposed vein, again as a sutureless technique ( Fig. 23.1 ). Despite theoretical advantages and widespread dissemination in World War II, the use of such tubes was limited by logistics and prolonged medical evacuation times of the wounded to surgical facilities.

Experimental use of intravascular shunts as a means of temporary restoration of blood flow has roots to both the French-Algerian war (1954–62) and the Soviet war in Afghanistan (1981–85). Both accounts described the use of temporary shunts to maintain blood flow to allow time for either onward transport, or to “administer antishock therapy.” Among the first modern descriptions of temporary shunts is that from Eger et al., who in 1971 used a temporary vascular shunt prior to orthopedic fixation. This practice ultimately demonstrated a decreased frequency of extremity amputation in the setting of complex popliteal artery injury.

Modern Use of Intravascular Shunts

Military and Combat Experience

Despite advances in civilian damage control, use of temporary vascular shunts in trauma had been limited to a few case series prior to the events of September 11, 2001. One bittersweet effect of war is the renaissance of surgical experience, technology, and technique. In a report from Operation Iraqi Freedom, Rasmussen et al. described a 1-year experience of 126 extremity vascular injuries, in which 30 temporary vascular shunts were utilized in the management of vascular injury. In this report, shunts were used as a damage control adjunct to either facilitate casualty evacuation, or to allow perfusion while other life-threatening injuries were managed. In this series, 57% of patients had patent shunts on arrival to a higher level of care (typically <2 hours after initial surgery). The authors noted that patency of the shunts hours after placement was higher (86%) when they had been used in larger, more proximal vessel injuries. The favorable experience with the use of vascular shunts in this initial report was corroborated by subsequent series provided by other combat surgical teams. Fig. 23.2 details a case example in which a mid-subclavian artery injury was initially treated at a forward surgical location with the insertion of an intraluminal shunt and subsequently repaired with interposition graft at a higher level of care.

Gifford and colleagues provided one of the only studies to characterize longer-term extremity outcomes following the use of temporary vascular shunts. In their study, the authors used case-controlled methodology to show that the use of temporary shunts had no adverse outcome in the years following vascular repair and likely extended the window for limb salvage, especially in the most severely injured extremities.

Indications

Damage control, that is, physiologic instability or presence of higher operative priorities precluding definitive reconstruction of the vascular injury, is the primary indication for the use of a temporary shunt. The rapid placement of a shunt is useful to reduce the time to reperfusion (i.e., oxygen delivery) beyond the disrupted vessel when there are other higher-priority management steps required. With the shunt in place, stabilization of associated fractures or performance of a laparotomy, craniotomy, or thoracotomy can be completed with the extremity or other end-organ perfused instead of having continued and compounding ischemic injury. Finally, expedited placement of a shunt may be useful if a surgeon desires to curtail the intervention due to lack of training in or comfort with performing the vascular reconstruction. Placement of a shunt in the setting of prolonged ischemia provides end-organ perfusion and may allow the infusion of medications designed to limit thrombosis or ischemia-reperfusion injury (e.g., heparin or mannitol). Use of a temporary shunt in an axial vessel of a severely mangled extremity allows for the limb to be stabilized, débrided, and reassessed at a second-look operation if needed. This strategy allows for a more organized mobilization of requisite surgical disciplines to assess the limb at a scheduled time after the initial operation has been performed. The indications for the use of temporary shunts are provided in Box 23.1 . Based upon early reports of successful use of vascular shunting in theater, the Department of Defense Joint Trauma System created a clinical practice guideline for extremity vascular injury that provided guidance on the use of vascular shunts. In its guidance to deploying surgeons, shunts should be considered for all extremity vascular injuries including proximal venous injuries.

Most situations of vascular injury afford the option of shunt placement, making rare contraindications for their use. Control of hemorrhage requires exposure where the decision to ligate or place a shunt can be made. Clearly, the patient would need to be in a stable enough condition to allow exploration of the vascular injury to commence with anticipated blood loss during that operation. With adequate exposure of the vascular injury, placing and securing a shunt can be done in the same amount of time as is needed to ligate both ends of a damaged blood vessel. Access to adequate shunt material (see subsequent section) is needed to successfully temporize the injury. In the extremity with multiple injuries and the possibility for vascular disruption in multiple segments, the surgeon must ensure re-establishment of flow does not lead to worsening hemorrhage. The tenant of damage control vascular surgery is the control of hemorrhage, with limitation of ischemic insult being a close second. Placement of a shunt to establish flow leading to continued hemorrhage from the limb would not be prudent. Additionally, reports demonstrate few ill effects from placement of shunts. Theoretically, further damage to the uninjured vessel after shunt placement, embolization of the shunt, occlusion, and/or dislodgment of the shunt could occur. These are of limited likelihood and one could argue that ligation leads to a worse outcome. Ligation after shunt placement is always a consideration; however, the reverse is unlikely to be an option due to distal thrombosis and loss of outflow.