GENERAL PRINCIPLES OF VASCULAR INJURY MANAGEMENT

NOTE: See Appendix A, Appendix B and Appendix C for management based on anatomic location and Appendix F for basic equipment list

Most deploying non-vascular or non-cardiothoracic surgeons will have limited recent experience in vascular surgery. Prior to deployment, all military surgeons should take the ASSET+ course (DoD developed course currently part of the Emergency War Surgery Course). ASSET+ training was developed by military surgeons for military surgeons to given them iterative training on vascular exposures. Training for surgeons should emphasize the basic principles of vascular trauma management, including adequate exposure, proximal and distal control, vessel debridement to viable tissue, the creation of a tension-free anastomosis, repair or shunt, and adequate coverage with viable tissue. The most challenging aspect in the management of a wartime vascular injury is generally related to vascular exposure. As most of these injuries involve previously normal blood vessels, vessel suturing, and shunt placement are usually a relatively straightforward technical exercise. However, in the face of tissue destruction, hematoma, distorted anatomic landmarks, and the potential absence of a palpable pulse, the identification and adequate exposure of a wartime vascular injury can be a challenge for even an experienced surgeon. While the deploying surgeon will find additional detail regarding techniques and “pearls” in the appendices extremely valuable for pre-deployment review and as a reference during deployment, surgeons should also maximize opportunities to review anatomic exposures in cadaveric, simulation, and video settings prior to deployment. Furthermore, an atlas that covers vascular surgery and exposures should be at the immediate ready for every surgeon on a combat deployment.

LIGATION OF VESSELS

Pearls

- Acceptable damage control maneuver especially for small, more distal arteries and veins.
- Temporary vascular shunting to restore perfusion should be considered before ligation.
- Continuous wave Doppler should be checked before ligation to judge collateral perfusion/viability.
- Ligation of vascular injuries was the mainstay of treatment for centuries and should not be overlooked as a damage control option, especially at Role 2 facilities where operations are best abbreviated (≤ 1 hr). This technique is especially useful in small distal vessels (tibial, forearm and arm below the take-off of the profunda brachial artery) when patients are in extremis. Use of temporary vascular shunts or even repair should be considered before ligation; however, if not available or feasible, ligation should be completed. Continuous wave Doppler may also be useful in assessing perfusion to the extremity distal to the vessel in question. If there is loss of an arterial bypass during the operation or shortly thereafter with associated venous ligation, consideration should be made for venous reconstruction as the arterial bypass may be lost due to reduced extremity outflow.

THROMBECTOMY

Pearls

Fogarty catheters are a key tool in the armamentarium of vascular injury management. Used primarily to remove thrombus, they can also be used to arrest bleeding from within the lumen of the vessel. The most common size used in extremity vascular injury is 2 and 3 Fr. At least one pass of a Fogarty should precede extremity vascular injury repair to assure removal of the traumatic thrombus burden before restoring inflow and outflow. The key tenet is not to cause native vessel damage. To lessen the risk of damage, avoid advancing the catheter too distal in the smaller vessels of the leg and arm and avoid over aggressive, static balloon inflation (i.e. angioplasty or “intimectomy”).

- Sized at 2-7 Fr; Commonly use 2 or 3 Fr catheters. Maximum balloon diameter of the 2 and 3 Fr catheters is 4 and 5 mm.
- Inflate with saline using 1cc tuberculin syringe (max inflation listed on the Fogarty hub) while withdrawing from vessel.
- Goal is clot, not intima, removal so don’t over-inflate or “drag” too much.
- A valuable tool in assessing the distance of the catheter placement and avoiding distal intimal injury is to measure externally on the skin the distance the catheter should pass.
- May be used to control bleeding from within the vessel lumen. Requires a 3-way stop cock to maintain inflation once the bleeding has been stopped.

TEMPORARY VASCULAR SHUNTS

Pearls

- Inline shunts rest in the vessel (“in-situ”) while long external shunts are designed to loop.
- In-line Argyle shunts come in a cylinder container with 8, 10, 12 and 14 Fr sizes.
- In-line Javid shunts are longer and individually packaged with a ribbed edge to help keep secure.
- Sundt shunts are designed with short (15cm; inline) and long (30cm; external) profiles with a ribbed edge to help keep secure.
- Equal success has been had with Argyle, Javid and Sundt without systemic anticoagulation.
- Proximal and Distal embolectomy should be performed prior to shunt placement.
- When cutting the shunt to size, there should be at least 4cm longer than the gap between the injured ends of the vessel. For example, if there is a 3cm gap, the shunt should be approximately 7cm long with 2cm of the shunt in both the proximal and distal injured vessel. (Figure 1). This is to allow 2cm of the shunt to be in the proximal and distal ends of the artery.
- Do not kink the shunt, as this will create turbulent flow and increase the risk of shunt thrombosis. (Figure 2)
- When placing the shunt, be careful not to injure the intima (particularly if the shunt was cut to size) as this can result in early shunt failure and necessitate a more complex definitive repair/reconstruction.
- Secured with silk ligatures no more than 1cm from each damaged end of the vessel; edges will be debrided to health tissue beyond the ligature prior to definitive repair. (Figure 1)
- If not secured well, shunts will have a tendency to migrate distally and even become dislodged. To prevent this from occurring:
  - All ‘tails’ are used (6 in total).
  - Vessel to vessel - not tight but to stabilize the two ends of the vessel to prevent further retraction.
  - Shunt to vessel on the proximal end.
  - Shunt to vessel distally.
  - Do not leave these silk tail long or there is a risk of an en-route care provide ‘pulling up on them’ should there be a concern for bleeding. Cut all the tails and temporarily close the wound.
  - Ensure there is a way for en-route care providers to attain proximal control if there is massive bleeding (from shunt dislodgement) during transport. This can be done with a proximal (pre-positioned) tourniquet or with vessel loops that have been secured appropriately.
- Patent for up to 6 hours; reports of longer duration exist.
- Consider shunting of concomitant vein injuries if possible.
- Shunts should be removed with formal repair in-theater prior to MEDEVAC to Role 4.
- Temporary vascular shunts are effective and should be considered in the management of nearly all extremity vascular injury patterns including proximal venous injuries. Their main advantage is provision of early restoration of flow and mitigation of the damaging effects of arterial ischemia and venous hypertension. As an abbreviated procedure compared to formal vascular repair, shunting extends the window of opportunity for limb salvage in some patterns of vascular injury. Although the patency at 3-4 hours is higher in larger, more proximal vessels (axillary/brachial and femoral/popliteal), shunts have been used effectively in smaller (distal brachial/forearm and tibial) vessels. Outcomes of extremity vascular injury managed with temporary shunts have been recorded demonstrating no adverse effect of this technique and a limb salvage advantage in the most severely injured limbs (MESS ≥ 8). 3,4,8,20

Figure 1. Temporary vascular shunt
Figure 2. Kinked vascular shunt
Figure 3. Example of vascular shunt in situ

HARVESTING & USE OF AUTOLOGOUS VEIN

Pearls

- Use reversed greater saphenous vein from uninjured extremity.
- Expose at saphenofemoral junction or anterior to medial malleolus (consistent locations).
- Be sure to mark anatomically distal end as “in-flow” assuring reversal of vein conduit. This is usually done with an ‘olive tipped’ vein cannulator that is secured in the distal end of the vein.
- Introduce 18 gauge plastic vein cannula (angiocatheter) or metallic olive tip cannula to distend the vein with heparin saline.
- Because of its versatility, resistance to infection, propensity for tissue incorporation and favorable patency rates, saphenous vein for interposition graft or patch material is favored. The greater saphenous veins may be consistently located at the saphenofemoral junction (2cm medial to the pubic tubercle) or 1-2 cm anterior to the medial malleolus. Identifying the actual saphenofemoral junction is important to confirm that the vein being exposed is truly the main channel saphenous and not an accessory branch or anterior saphenous (i.e. must follow back to main saphenofemoral junction). In the setting of trauma, the vein frequently appears in-situ as “too small” or “not adequate” due to vasoconstriction or spasm.
- Nonetheless, after confirming that the vein being exposed is the main channel saphenous, the specimen should be removed and dilated on the back table with firm infusion of heparin saline using a 14–18-gauge plastic vein cannula or the metallic olive tip cannula. Persistence and this maneuver almost always result in a markedly improved and dilated vein ready to be used for repair. Reversal of the vein must also be confirmed as venous valves will not permit flow in a retrograde fashion. Smaller sutures (7-0 prolene) are often necessary if side branches need more control than that afforded by initial harvest.

Be sure to mark anatomically distal end as “in-flow” assuring reversal of vein conduit.

USE OF PROSTHETIC GRAFT MATERIAL

Pearls

- ePTFE (Gortex) or Dacron used for central torso vascular injuries (aorta, great vessels).
- Prosthetic conduit acceptable as last resort in extremities when there are no shunts, the vein is being preserved for definitive care at a later time, or the vein cannot be harvested.
- If prosthetic used in extremity injury, notify higher levels of care to facilitate surveillance.
- Prosthetic graft materials such as ePTFE (Gortex) or Dacron should be reserved for open reconstruction of the aorta and large torso vessels and used very rarely as conduit for extremity vascular injury. Wartime experience has demonstrated poor incorporation of prosthetic grafts in extremity wounds and a propensity for infection compared to saphenous vein. Additionally, extrapolation of civilian data suggests improved patency of vascular reconstructions using saphenous vein. In the rare instance (i.e. damage control) when prosthetic conduit is used for extremity vascular injury, communication with higher levels of care should occur so that appropriate surveillance or even removal of the graft and replacement with vein can occur. 3

ANASTOMOTIC CONSIDERATIONS

Spatulate or Bevel the Conduit

Purpose: to prevent stenosis and mitigate size mismatch between conduit and in situ vessel

Bevel: to cut the edge of the conduit and in situ vessel (Figure 4)

Spatulate: to open the vessel to increase diameter (Figure 5)

Figure 4.
Figure 5.

ANASTOMOSIS TECHNIQUE: PARACHUTE VS TWO-POINT VS SINGLE-POINT FIXATION

Parachute

At the beginning of the anastomosis, no knot is started (Figure 6). Sutures are placed in a running fashion until the conduit is “parachuted down.” A knot is tied at the end of the anastomosis. This technique is helpful when sewing down to something with difficult exposure (pelvis), although some surgeons prefer this technique in every case.

Figure 6.

Two-Point Fixation

The anastomosis is started on the bottom, in which a knot is tied. A second suture is placed on the opposite side of the first knot (Figure 7). This can either be tied down or tagged to assist with offloading tension. Sutures may be placed in a running fashion from either knot and met in the middle (Figures 7 and 8). This technique is helpful when sewing vessels that are under some tension, but some surgeons always prefer this method.

Figure 7.
Figure 8.

Single-Point Fixation

Similar to the two-point fixation, but a single knot is placed on the bottom of the vessels (Figure 9). The anastomosis is then carried around each side until the end, in which another knot is tied down to complete the anastomosis.

Figure 9.

SOFT TISSUE COVERAGE & ANASTAMOTIC DISRUPTION

Pearls

- Cover vascular repairs with available viable local tissue (muscle and soft tissue pedicles).
- If no soft tissue to cover, route grafts out of zone of injury (extra-anatomic).
- A poorly covered vascular anastomosis or an anastomosis in an infected wound bed, can “blowout,” but not in the early (< 5 day) period.
- Avoid direct placement of negative pressure wound therapy sponge on vascular structures.
- Soft tissue coverage of vascular repairs is required to assure incorporation and prevent infection and blowout. Option 1 is to immediately cover the repair with viable local soft tissue (muscle and adipose). If available, the negative pressure wound therapy device (VAC) is useful on top of such coverage as it provides a closed dressing which removes wound effluent and decreases bacterial counts. This wound adjunct has been found to assist with accomplishing delayed primary closure of soft tissue wounds over vascular repairs or coverage with skin grafts. The reticulated open-cell foam sponge of the VAC should not be placed directly on vessels; however, when used over viable tissue covering the vascular repair, VAC has resulted in excellent outcomes with no increase in graft-related complications or blowouts.1 If there is no viable tissue option to cover the repair, the white foam vac dressing may be used to cover the vessel, but NEVER the black foam dressing.
- If no tissue is available to cover the vascular repair, one can route an interposition graft out of the zone of injury through another myocutaneous or even subcutaneous path (extra-anatomic). As a last resort, the vascular reconstruction can be left with marginal coverage at Role 2 and 3 facilities; however, in these cases close examination must occur at Role 4 facilities. In these rare instances higher levels of care should pursue transfer of viable tissue from other locations (sartorius, rectus abdominis or other muscle) to definitively cover the repair within 5-7 days. Although it is acceptable for Role 2 and 3 providers to leave a graft with uncertain coverage, the onus of care then falls heavily on Role 4 facilities to inspect, cover, re-route or even ligate the graft to reduce the risk of catastrophic blowout. When soft tissue coverage is not possible, consideration should be made for constant proximal tourniquet placement in the event of blowout and application by nursing or evacuation assets.
- It is important to recognize that even in the best of civilian and wartime circumstances that there has been historically and remains currently a finite risk of anastomotic disruption. Using the management strategies described above the risk of graft blowout has been within an acceptably low range of 1-2% throughout the wars in Iraq and Afghanistan.19,21

LARGE VEIN INJURIES

Pearls

- Formal control (DeBakey clamps) is acceptable but may be difficult or not advisable as it risks causing injury or may not be needed if injury is limited to the side wall of the vein.
- Initial control can be accomplished by one or more fingers on the bleeding segment.
- Organize the operating room and confirm availability of blood and central venous access.
- Central venous access above the heart if operating on injury to the inferior vena cava. If operating on an injury in the chest, central venous access is ideally at the femoral vein.
- Optimal lighting, exposure (i.e. extend incisions) and two or more suction devices.
- Avoid too small of a needle and suture which are difficult to maneuver in blood. 4-0 Prolene on an SH tapered needle is substantive suture on a needle large enough to see.
- Fingers replaced with a low profile tampanode device such as a small sponge stick or Wecksorb “K” dissector (i.e. Kitner device) as bleeding is evacuated.
- Passes of suture are made capturing muscle or soft tissue if possible (i.e. pledget-effect). Tie the knot to begin running venorrhaphy or place second pass in “figure-of-8” fashion.
- Felt pledgets can be used but may not be available.
- Hemorrhage control with ligation is preferable to patency with death from exsanguination.