Temporary arterial shunts to maintain limb perfusion after arterial injury: an animal study

Performance of a novel temporary arterial shunt in a military-relevant controlled hemorrhage swine model

BACKGROUND

In military trauma, temporary vascular shunts restore arterial continuity until delayed vascular reconstruction, often for a period of hours. A novel US Air Force-developed trauma-specific vascular injury shunt (TS-VIS) incorporates an accessible side port for intervention or monitoring, which may improve patency under adverse hemodynamic conditions. Our objective was to evaluate TS-VIS patency in the setting of volume-limited resuscitation from hemorrhagic shock.

METHODS

Female swine (70-90 kg) underwent 30% hemorrhage and occlusion of the left external iliac artery for 30 minutes. Animals were allocated to one of three groups (n = 5 per group) by left external iliac artery treatment: Sundt shunt (SUNDT), TS-VIS with arterial pressure monitoring (TS-VIS), or TS-VIS with heparin infusion (10 μ/kg per hour, TS-VISHep). Animals were resuscitated with up to 3 U of whole blood to maintain a mean arterial pressure (MAP) of >60 mm Hg and were monitored for 6 hours. Bilateral femoral arterial flow was continuously monitored with transonic flow probes, and shunt thrombosis was defined as the absence of flow for greater than 5 minutes.

RESULTS

No intergroup differences in MAP or flow were observed at baseline or following hemorrhage. Animals were hypotensive at shunt placement (MAP, 35.5 ± 7.3 mm Hg); resuscitation raised MAP to >60 mm Hg by 26.5 ± 15.5 minutes. Shunt placement required 4.5 ± 1.8 minutes with no difference between groups. Four SUNDT thrombosed (three before 60 minutes). One SUNDT thrombosed at 240 minutes, and two TS-VIS and one TS-VISHep thrombosed between 230 and 282 minutes. Median patency was 21 minutes for SUNDT and 360 minutes for both TS-VIS groups (p = 0.04). While patent, all shunts maintained flow between 60% and 90% of contralateral.

CONCLUSION

The TS-VIS demonstrated sustained patency superior to the Sundt under adverse hemodynamic conditions. No benefit was observed by the addition of localized heparin therapy over arterial pressure monitoring by the TS-VIS side port.

Temporary intravascular shunts after civilian arterial injury: A prospective multicenter Eastern Association for the Surgery of Trauma study

INTRODUCTION

We sought to determine the impact of the indication for shunt placement on shunt-related outcomes after major arterial injuries. We hypothesized that a shunt placed for damage control indications would be associated with an increase in shunt-related complications including shunt dislodgement, thrombosis, or distal ischemia.

PATIENTS & METHODS

A prospective, multicenter study (eleven level one US trauma centers) of all adult trauma patients undergoing temporary intravascular shunts (TIVS) after arterial injury was undertaken (January 2017-May 2019). Exclusion criteria included age <15years, shunt placement distal to popliteal/brachial arteries, isolated venous shunts, and death before shunt removal. Clinical variables were compared by indication and shunt-related complications. The primary endpoint was TIVS complications (thrombosis, migration, distal ischemia).

RESULTS

The 66 patients who underwent TIVS were primarily young (30years [IQR 22-36]) men (85%), severely injured (ISS 17 [10-25]) by penetrating mechanisms (59%), and had their shunts placed for damage control (41%). After a median SDT of 198min [89-622], 9% experienced shunt-related complications. Compared by shunt placement indication (damage control shunts [n=27] compared to non-damage control shunts [n=39]), there were no differences in gender, mechanism, extremity AIS, MESS score, fractures, or surgeon specialty between the two groups (all p>0.05). Patients with shunts placed for damage control indications had more severe injuries (ISS 23.5 compared to 13; SBP 100 compared to 129; GCS 11 compared to 15; lactate 11.5 compared to 3.6; all p<0.05), and had more frequent shunt complication predictors, but damage control shunts did not have significantly more TIVS complications (11.1% compared to 7.7%, p=0.658). Shunt complication patients were discharged home less often (33% vs 65%; p<0.05) but all survived.

CONCLUSION

Shunts placed for damage control indications were not associated with shunt complications in this prospective, multicenter study.

Time to Failure of Arterial Shunts in a Pig Hemorrhagic Shock Model

Temporary vascular shunts (TVSs) are relied on frequently in the current military theater. Details of their physiology and outcome are of increasing interest and needed to further define their place in the management of trauma. This study was conducted using a porcine hemorrhagic shock model and aimed to 1) establish the time to failure of short, proximally placed vascular shunts; and 2) examine histological changes in the shunted artery. The external iliac artery of male pigs was transected and a straight shunt secured in place. Hemorrhagic shock was then induced by rapidly removing 40 per cent of blood volume and maintaining severe hypotension for 40 minutes before resuscitation. Animals were observed for up to 6 days for limb function as well as overall physiological status. At the conclusion of the experiment, status of the shunt and adjacent artery was evaluated by an independent pathologist. The presence of thrombi and inflammation within the proximal and distal artery was graded. Among the 10 animals tested, nine subjects survived the initial surgery. All shunts remained patent with mean time of 4.2 61.2 days of observation. Three-position histological analysis of the connected arterial tissues revealed minimal acute inflammation and minimal or thrombus. The results suggest that TVSs in proximal arteries remain functional for at least 48 to 72 hours in proximal arteries even without anticoagulation in the setting of brief hemorrhagic shock. This knowledge may aid combat evacuation patterns.

Development of a Puncture Technique for Implanting Temporary Vascular Shunts in a Porcine Model

BACKGROUND

Temporary vascular shunts (TVSs) are an effective tool for rapidly restoring blood flow to a limb or organ that has experienced vascular injury and ischemia and for which revascularization is not an immediate option. Usually, through an opening in the skin, the TVS is positioned within the proximal and distal stumps of the injured vessel, restoring perfusion and stopping the ischemia. The aim of this study is to compare standard TVS technique and a developed puncture technique for implanting TVS and to evaluate the utility and feasibility of this protocol after arterial lesions, in pigs.

METHODS

Vascular injuries were inflicted in both hind limbs of 30 pigs, and vascular interventions were performed, using standard and puncture TVS. Because each pig was implanted with both types of TVSs, it was possible to simultaneously monitor, analyze, and compare parameters such as, the mean arterial pressure (MAP, in mm Hg), blood flow (mL/min), and insertion times, in the same animal.

RESULTS

It was observed that the MAP in the limbs recovered and approached systemic MAP, in 100% of the experiments, in both groups. Analysis of the blood flow data showed that this parameter was significantly reduced in the puncture TVS group (110.36 ± 9.99 mL/min vs. 153.20 ± 18.57 mL/min, P = 0.001). On the other hand, the insertion time for the standard TVS was significantly greater than that of the puncture shunt (15.32 ± 3.08 min vs. 10.37 ± 1.7 min, P = 0.001). Furthermore, it was found that the primary and secondary patency and complication rates were similar for both TVS types.

CONCLUSION

Thus, given the adequate MAP recovery and reduction in implantation time observed in this experimental and in an animal model study, the use of the puncture TVS technique is effective and feasible.

Temporary arterial shunts in damage control: Experience and outcomes

BACKGROUND

Arterial shunting is a well-described method to control hemorrhage and rapidly reestablish flow, but optimal shunt dwell times remain controversial. We hypothesized that prolonged shunt dwell times of more than 6 hours are related to adverse outcomes after major arterial injury.

METHODS

A review (2005-2013) of all patients with arterial shunts placed after traumatic injury at our urban Level I trauma center was undertaken. Patients who died prior to shunt removal (n = 7) were excluded. Shunt complications were defined as dislodgement, thrombosis, and distal ischemia. Patients were compared on the basis of shunt complications with respect to clinical parameters.

RESULTS

The 42 patients who underwent arterial shunting after major vascular injury were primarily young (median, 26 years; interquartile range [IQR], 22-31 years) males (97.6%), severely injured (Injury Severity Score, 17.5 [IQR, 14-29]; shunted vessel Abbreviated Injury Scale score, 4 [IQR, 3-4]) by gunshot (85.7%) requiring neck/torso (33.3%) or upper-extremity (19.1%) or lower-extremity (47.6%) shunts. Thirty-five patients survived until shunt removal, and 5 (14.3%) of 35 developed shunt complications. Demographics and clinical characteristics were compared between those with shunt dwell times of less than 6 hours (n = 19) and more than 6 hours (n = 16). While patients appeared to have a greater injury burden overall in the group with dwell times of more than 6 hours, there were no statistical differences between groups with respect to age, gender, initial systolic blood pressure or hemodynamics during the shunt dwell period, use of vasopressors, Abbreviated Injury Scale score of the shunted vessel, Injury Severity Score, or outcomes including limb amputation or mortality. No patients (0/19) with shunt dwell times of less than 6 hours developed complications, whereas 5 (31.3%) of 16 patients with dwell times of more than 6 hours developed shunt complications (p = 0.05).

CONCLUSIONS

In this civilian series, 14% of patients with arterial shunts developed shunt complications. Our data suggest that limiting shunt dwell times to less than 6 hours when clinically feasible may decrease adverse outcomes.

LEVEL OF EVIDENCE

Therapeutic/care management study, level IV.

Successful Limb Reperfusion Using Prolonged Intravascular Shunting in a Case of an Unstable Trauma Patient

When peripheral vascular injuries present in conjunction with life threatening emergencies, controlling hemorrhage from a peripheral blood vessel may take initial priority, however, sacrificing a limb to preserve life is a well-established dictum. The use of intravascular shunts has allowed arterial and venous injuries to be controlled and temporized while treating other injuries. Typically, intravascular shunts are used for short time periods while orthopedic injuries are repaired or other life threatening injuries are managed. The following case demonstrates the long-term use of an intravascular arterial shunt to treat a traumatic transection of the common femoral artery and vein in a patient with an open pelvic fracture from blunt trauma. A 20-year-old woman fell between a subway platform and an oncoming train. She sustained a crush injury to her lower extremity and pelvis as she was pinned between the train and platform. The patient presented with active hemorrhage from a groin laceration, quickly became hemodynamically unstable, and was brought to the operating room. In addition to a pelvic fracture with massive pelvic hematoma she sustained a complete transection of the bifurcation of the common femoral artery (CFA), the common femoral vein (CFV), and associated orthopedic injuries. Vascular shunts were placed in the common femoral artery and vein. The patient became hypotensive from an expanding retroperitoneal hematoma. Pelvic bleeding was controlled with angioembolization and the venous injury was repaired. At this time the patient became cold, acidotic, and coagulopathic. It was thought unsafe to proceed with the arterial repair and it was elected to keep her arterial shunts in place and perform a planned reexploration in 24 hours after correcting her physiologic status. The patient returned to the operating room for an elective repair of her CFA the following day. Her shunt had remained patent throughout this time. She underwent a reverse saphenous vein graft from her CFA to her SFA. After a prolonged hospital course she was ultimately transferred to a rehabilitation center with intact pulses in both lower extremities. This case demonstrates the effectiveness of prolonged (>6 hours) use of an intravascular shunt as part of damage control surgery for peripheral arterial and venous injuries. In a patient who would otherwise undergo an amputation for their injury, the risk of shunt thrombosis, or infection, during damage control resuscitation may not be a contraindication for placement.

Temporary vascular shunt for damage control of extremity vascular injury: A toolbox for trauma surgeons

In an emergency, a general surgeon may be faced with the need to treat arterial trauma of the extremities when specialized vascular surgery is not available in their hospital setting, either because an arterial lesion was not diagnosed during pre-admission triage, or because of iatrogenic arterial injury. The need for urgent control of hemorrhage and limb ischemia may contra-indicate immediate transfer to a hospital with a specialized vascular surgery service. For a non-specialized surgeon, hemostasis and revascularization rely largely on damage control techniques and the use of temporary vascular shunts (TVS). Insertion of a TVS is indicated for vascular injuries involving the proximal portion of extremity vessels, while hemorrhage from distal arterial injuries can be treated with simple arterial ligature. Proximal and distal control of the injured vessel must be obtained, followed by proximal and distal Fogarty catheter thrombectomy and lavage with heparinized saline. The diameter of the TVS should be closely approximated to that of the artery; use of an oversized TVS may result in intimal tears. Systematic performance of decompressive fasciotomy is recommended in order to prevent compartment syndrome. In the immediate postoperative period, the need for systematic use of anticoagulant or anti-aggregant medications has not been demonstrated. The patient should be transferred to a specialized center for vascular surgery as soon as possible. The interval before definitive revascularization depends on the overall condition of the patient. The long-term limb conservation results after placement of a TVS are identical to those obtained when initial revascularization is performed.

Reperfusion strategies in the management of extremity vascular injury with ischaemia

BACKGROUND

Extremity injury with ischaemia is the most common pattern of vascular trauma and is a challenge for surgeons who must make decisions about the timing and mechanism of limb reperfusion. In modern military conflicts, effective use of limb tourniquets and rapid transport of the injured have increased the number of casualties who reach a medical service with potentially survivable vascular trauma. This report provides a review of extremity ischaemia and reperfusion following vascular trauma.

METHODS

A review was undertaken of extremity vascular injury with ischaemia, including a focus on adjuncts aimed at reducing reperfusion injury and improving neuromuscular recovery and limb salvage.

RESULTS

Findings from basic and clinical research support the need to restore perfusion to an ischaemic limb as soon as possible in order to achieve optimal neuromuscular recovery. Large-animal studies demonstrate that haemorrhagic shock worsens the impact of ischaemia on the neuromuscular structures of the limb and reduces the ischaemic threshold to as little as 1 h. Surgical adjuncts such as vascular shunts, fasciotomy, regional limb cooling and ischaemic conditioning may reduce the severity of ischaemic injury. Medical therapies have also been described including hypertonic saline, statins and ethyl pyruvate, which reduce the inflammatory response following limb reperfusion.

CONCLUSION

Contemporary translational research refutes a casual approach to extremity vascular injury with ischaemia, instead emphasizing expedited reperfusion. Surgical and medical adjuncts exist to expedite reperfusion and mitigate reperfusion injury. Additional research and development of these adjuncts is necessary to improve quality or functional limb salvage after vascular trauma.

Temporary vascular shunts

Temporary vascular shunts have been used for nearly 100 years in patients. Originally, they were used as vascular grafts that were likely to thrombose as collaterals would hopefully develop. More recently, they have been used as a device to be replaced by a permanent vascular graft during the same operation or at a reoperation. Indications for the use of shunts are a "damage control" procedure for a peripheral or truncal vascular injury, Gustilo IIIC fracture of an extremity, need for perfusion as a complex revascularization is performed, and planned replantation of a hand, forearm, or arm. They are used in approximately 8% of vascular injuries treated in urban trauma centers in the United States and have an excellent patency rate without heparinization.

High-energy trauma and damage control in the lower limb

Management of traumatic lower-limb vascular injury can offer special challenges even to experienced surgeons. Recent U.S. conflicts have advanced the practice of vascular trauma surgery on the battlefield and offer important lessons learned for management of similar injury in urban trauma centers. Damage control techniques for complex injuries when associated with hemodynamic instability may provide an opportunity to save both life and limb. This article provides an overview of damage control principles in the management of high-energy traumatic vascular injuries of the lower limb during recent U.S. military combat operations.

Early versus delayed restoration of flow with temporary vascular shunt reduces circulating markers of injury in a porcine model

BACKGROUND

Temporary vascular shunting to restore flow after vascular injury has been advocated. The effectiveness of this adjunct in protecting against ischemic injury has not been established. This study will assess the temporal impact of shunts on ischemic injury and arterial flow.

METHODS

A porcine model of hind-limb ischemia via iliac artery occlusion was used (N = 36; weight [kg] +/- SD: 89 +/- 4.4). Animals were randomized into one control (Iscctrl) and four study groups (Isc0, Isc1, Isc3, and Isc6) according to ischemic time. Shunt placement followed ischemia, and flow and circulating injury markers were collected incrementally during 18 hours of reperfusion. Flow proportions and a calculated Ischemia Injury Index were used to characterize group differences.

RESULTS

There were no intergroup differences concerning initial weight, hemodynamic, or laboratory values. Shunt patency was 92% in the absence of anticoagulation. The proportion of common femoral arterial flow to baseline flow in the Isc6 group was lower than the Iscctrl group (p = 0.02). There was a similar trend with the Isc1 and Isc3 groups. The Ischemia Injury Index demonstrated that there was a difference in the Isc3 and Isc6 groups (late shunt placement) compared with the Iscctrl, Isc0, and Isc1 groups (early shunt placement) (p < 0.001).

CONCLUSION

This study provides physiologic insight into the benefit of shunts in a model of extremity ischemia. Early shunting protects the extremity from further ischemic insult and reduces circulating markers of tissue injury. Additionally, the presence of a shunt does not increase the Ischemic Injury Index and patency is maintained in the absence of heparinization.

Temporary intravascular shunting improves survival in a hypothermic traumatic shock swine model with superior mesenteric artery injuries

BACKGROUND

Repairs of superior mesenteric artery (SMA) injuries are difficult and often result in high mortality. Our group has employed temporary intravascular shunts (TIVS) as a damage control procedure in a SMA transection model and hypothesized that TIVS would improve survival when compared with primary vascular anastomosis in the setting of a damage control surgery.

METHODS

The SMA was clamped and completely transected while pigs were hemorrhaged to a mean arterial pressure of 40 mmHg and maintained in shock for 30 minutes. Cold lactated Ringer's solution was gradually infused while the abdomen was open to induce hypothermia. Animals were randomized to control (no resuscitation), primary anastomosis (PA), or temporary shunting (TS) of the SMA. Animals were resuscitated for 6 hours with the shed blood and lactated Ringer's solution. Delayed anastomosis was performed in TS animals after resuscitation. Surviving animals were humanely killed 2 days after operation. Systemic hemodynamic parameters were recorded hourly. The ileum was harvested at the end of resuscitation and experiment for pathologic evaluation.

RESULTS

All animals suffered extreme physiologic conditions: hypothermia, severe acidosis, hypotension, and depressed cardiac output and oxygen delivery. Control animals suffered 100% mortality. Compared with the PA group, TS animals required less resuscitation fluid, retained higher SMA flow rates, normalized lactate levels faster, suffered less severe intestine histopathology, and had greater early survival.

CONCLUSION

Damage control surgery in the setting of SMA transection seems better managed with TS than with PA. Further validation of this model is required before generalization to human applications.

Temporary femoral artery bifurcation shunting following penetrating trauma

Penetrating common femoral artery injuries are life-threatening, especially when the femoral bifurcation has been destroyed. In the presence of other associated injuries which preclude immediate definitive vascular reconstruction, temporary arterial shunting may be useful. Presently available shunts, however, are tubular and allow for distal perfusion to only one vessel. We have utilized a modified bifurcated hemodialysis catheter (Mahurkar MAXID; Tyco Healthcare, Mansfield, Mass) to successfully provide simultaneous perfusion from the proximal common femoral artery to both the superficial and deep femoral vessels. Such catheters are readily available in most institutions, can be quickly modified, and are easy use in urgent trauma situations.

Temporary intravascular shunts used as a damage control surgery adjunct in complex vascular injury: collective review

In this systemic review, we summarise the types, configurations, durations, indications and complications of the temporary intravascular shunts used as an adjunct of damage control surgery (DCS) in severe vascular injuries. We conclude that temporary intravascular shunts can be used without systemic anticoagulation for a prolonged time to maintain distal perfusion in combined orthopaedic and vascular injuries, in the setting of DCS and transferring.

Tactical Surgical Intervention With Temporary Shunting of Peripheral Vascular Trauma Sustained During Operation Iraqi Freedom: One Unit??s Experience

BACKGROUND

Rapidly restoring perfusion to injured extremities is one of the primary missions of forward military surgical teams. The austere setting, limited resources, and grossly contaminated nature of wounds encountered complicates early definitive repair of complex combat vascular injuries. Temporary vascular shunting of these injuries in the forward area facilitates rapid restoration of perfusion while allowing for deferment of definitive repair until after transport to units with greater resources and expertise.

METHODS

Standard Javid or Sundt shunts were placed to temporarily bypass complex peripheral vascular injuries encountered by a forward US Navy surgical unit during a six month interval of Operation Iraqi Freedom. Data from the time of injury through transfer out of Iraq were prospectively recorded. Each patient's subsequent course at Continental US medical centers was retrospectively reviewed once the operating surgeons had returned from deployment.

RESULTS

Twenty-seven vascular shunts were used to bypass complex vascular injuries in twenty combat casualties with a mean injury severity score of 18 (range 9-34) and mean mangled extremity severity score of 9 (range 6-11). All patients survived although three (15%) ultimately required amputation for nonvascular complications. Six (22%) shunts clotted during transport but an effective perfusion window was provided even in these cases.

CONCLUSION

Temporary vascular shunting appears to provide simple and effective means of restoring limb perfusion to combat casualties at the forward level.

Mortality from Isolated Civilian Penetrating Extremity Injury

BACKGROUND

Although studies have ascertained that ten percent of soldiers killed in battle bleed to death from extremity wounds, little data exists on exsanguination and mortality from extremity injuries in civilian trauma. This study examined the treatment course and outcomes of civilian patients who appear to have exsanguinated from isolated penetrating extremity injuries.

METHODS

Five and 1/2 years' data (Aug 1994 to Dec 1999) were reviewed from two Level I trauma centers that receive 95% of trauma patients in metropolitan Houston, TX. Records (hospital trauma registries, emergency medical system (EMS) and medical examiner data) were reviewed on all patients with isolated extremity injuries who arrived dead at the trauma center or underwent cardiopulmonary resuscitation (CPR) or emergency center thoracotomy (ECT).

RESULTS

Fourteen patients meeting inclusion criteria were identified from over 75,000 trauma emergency center (EC) visits. Average age was 31 years and 93% were males. Gunshot wounds accounted for 50% of the injuries. The exsanguinating wound was in the lower extremity in 10/14 (71%) patients and proximal to the elbow or knee in 12/14 (86%). Ten (71%) had both a major artery and vein injured; one had only a venous injury. Prehospital hemorrhage control was primarily by gauze dressings. Twelve (86%) had "signs of life" in the field, but none had a discernable blood pressure or pulse upon arrival at the EC. Prehospital intravenous access was not obtained in 10 patients (71%). Nine patients underwent ECT, and nine were initially resuscitated (eight with ECT and one with CPR). Those undergoing operative repair received an average of 26 +/- 14 units of packed red blood cells. All patients died, 93% succumbing within 12 hours.

CONCLUSION

Although rare, death from isolated extremity injuries does occur in the civilian population. The majority of injuries that lead to immediate death are proximal injuries of the lower extremities. The cause of death in this series appears to have been exsanguination, although definitive etiology cannot be discerned. Intravenous access was not obtainable in the majority of patients. Eight patients (57%) had bleeding from a site that anatomically might have been amenable to tourniquet control. Patients presenting to the EC without any detectable blood pressure and who received either CPR or EC thoracotomy all died.

Damage control in the abdomen and beyond

Background

Damage control is not a modern concept, but the application of this approach represents a new paradigm in surgery, borne out of a need to care for patients sustaining multiple high-energy injuries.

Methods

A Medline search was performed to locate English language articles relating to damage control procedures in trauma patients. The retrieved articles were manually cross-referenced, and additional academic and historical articles were identified.

Results and conclusion

Damage control surgery, sometimes known as ‘damage limitation surgery’ or ‘abbreviated laparotomy’, is best defined as creating a stable anatomical environment to prevent the patient from progressing to an unsalvageable metabolic state. Patients are more likely to die from metabolic failure than from failure to complete organ repairs. It is with this awareness that damage control surgery is performed, enabling the patient to maintain a sustainable physiological envelope.

Blunt vascular trauma in the extremity: diagnosis, management, and outcome

BACKGROUND

Blunt vascular trauma in an extremity is an uncommon diagnosis. Considering the complexity of these injuries, it is worthwhile to determine how select factors affect the outcome of the limb and the patient. The objectives of this study were to review the diagnosis, management, and outcomes of patients who sustained blunt vascular injuries in the extremities and relate factors in their treatment to the outcome of the injured extremity.

METHODS

A retrospective review of data on adult and pediatric patients who had a diagnosis of blunt vascular injury in an extremity and underwent some attempt at restoration of vascular flow was conducted.

RESULTS

From January 1995 to December 2002, 62 patients (80.3% male; mean age, 33.2 +/- 15.8 years) sustained blunt trauma (mean Injury Severity Score, 14.6 +/- 8.4), with 93 vascular injuries in 65 extremities (16 upper and 49 lower). Hard signs of vascular injury occurred in 41 (66%) patients. An associated fracture and/or dislocation was present in 59 patients (95%). Preoperative arteriograms were obtained in 20 patients (17 occlusions, 2 embolizations, and 1 untreated). Vessel injuries were as follows: 16 upper (brachial artery, 50%) and 63 lower (tibial/peroneal/popliteal, 84%), with ligation being the most common treatment in the latter. Intravascular shunts were used to restore blood flow in 18 vessels (13 arteries and 5 veins) in 13 patients. Delays in diagnosis or treatment occurred in six patients, mostly because of errors in management/judgment. Delayed or late fasciotomies were performed in six patients, and five developed rhabdomyolysis. Six patients died. The age (p = 0.0006), Injury Severity Score (p = 0.0007), and Mangled Extremity Severity Score (p = 0.0009) were significantly different for the survivors compared with the nonsurvivors.

CONCLUSION

Blunt vascular injuries in the lower extremities occur most commonly in the anteroposterior tibial arteries; injured arteries in the proximal upper and lower extremity require resection with interposition grafting, whereas those in the forearm or calf are usually ligated; the amputation rate in 65 injured extremities with blunt vascular trauma was 18.%, which is at least three times that for those who sustain penetrating injury; and delays in diagnosis and treatment are uncommon in these patients with multiple injuries.

Temporary intravascular shunt in complex extremity vascular injuries

BACKGROUND

Early revascularization of ischemic limbs is an important step in the management of complex extremity vascular injuries (CEVIs). We present our experience of using a temporary intravascular shunt (TIVS) in the management of patients with limb-threatening vascular injuries.

METHODS

Patients who had CEVIs at our institution from January 1996 to December 2000 were treated with early insertion of a TIVS at the initial phase of operations. The TIVSs were assembled from simple intravenous and extension tubes available in the operating room. Rigid stabilization of the injured bones and/or joints, debridement of the devitalized soft tissues, saphenous vein harvest for interposition grafts, and repair of any associated venous injuries were performed while the shunts were in place. Then, the shunts were removed and the injured arteries were repaired.

RESULTS

There were five men and two women in this series. The preoperative time ranged from 120 to 450 minutes (median, 390 minutes). All TIVSs were inserted within the initial 30 minutes of operation. The injured arteries were popliteal (five patients), common femoral (one patient), and brachial arteries (one patient). Three patients also had associated venous injuries (i.e., two popliteal veins and one common femoral vein). Six injured arteries were repaired with reversed saphenous vein grafts and one (popliteal artery) was repaired by end-to-end anastomosis. The shunt time ranged from 60 to 180 minutes (median, 120 minutes). One patient had a TIVS inserted into both injured popliteal artery and vein. The operative time ranged from 225 to 360 minutes (median, 285 minutes). No complications related to shunt insertion were observed and all limbs could be salvaged.

CONCLUSION

A self-constructed shunt is inexpensive, safe, and convenient to insert. Early revascularization of the injured limb with a TIVS can eliminate the adverse effects of prolonged ischemia and enables the surgeons to manage other associated injuries in an unhurried manner. We recommend early insertion of TIVSs in CEVIs.

Prolonged use of intraluminal arterial shunts without systemic anticoagulation

BACKGROUND

Temporary arterial shunts maintain perfusion while surgeons postpone arterial repairs. The common indications are combined orthopedic and vascular injuries and damage control. The duration of patency and the need for systemic anticoagulation remain in question. We examined our experience for answers.

METHODS

We searched for patients who had temporary arterial shunts and collected the following: mechanism, artery injured, shunt time, blood loss and transfusions, injury severity score (ISS,) mangled extremity severity score (MESS,) and anticoagulation.

RESULTS

Of 19 patients, 10 had shunts for damage control (group 1,) and 9, for orthopedic/vascular injuries (group 2.) group 1 had significantly higher shunt time, mortality, ISS, and MESS. Shunt time ranged from 47 to 3,130 minutes (52 hours.) Two patients, 1 in each group, required amputations.

CONCLUSION

Temporary arterial shunts can be use for combined orthopedic and vascular injuries and for damage control. Shunts can stay open for 52 hours without systemic anticoagulation.

Animal models for studies on cold-induced platelet activation in human beings

When human platelets are chilled below about 20 degrees C, they spontaneously activate, a phenomenon that limits their storage lifetime. We have previously shown that this activation in chilled human platelets is associated with passage through a lipid phase transition. Because animal models are necessary for Investigating methods for cold storage of platelets, it is essential to determine whether such phase transitions and chilling-induced activation are found in these models. In this study we examined platelets from some commonly used animal models-pigs, rhesus monkeys, mice, dogs, and rabbits. Using Fourier transform infrared spectroscopy (FTIR), we detected the thermotropic membrane phase transition in Intact platelets and assessed the morphologic response of the platelets to chilling. Statistical analysis of both FTIR and shape change show that of the animal models tested, pig platelets are most similar to human platelets. These studies suggest that pigs and pig platelets are the models of choice for the study of cold-induced platelet activation in human beings.