To Shunt or Not to Shunt? An Experimental Study Comparing Temporary Vascular Shunts and Venous Ligation as Damage Control Techniques for Vascular Trauma

Prognostic factors for femoropopliteal vascular injuries: surgical decisions matter

Background

Lower limbs are frequently involved in vascular trauma, but it is still not clear which factors lead to unfavorable clinical outcomes.

Objectives

To determine the clinical profile of patients with femoropopliteal injuries, the trauma mechanisms, and treatment and identify which factors led to unfavorable outcomes.

Methods

A retrospective study based on the medical records of patients treated from 2017 to 2021. The following data were assessed: sex, age, distance to reach the hospital, trauma mechanism, hypovolemic shock, additional injuries, treatment of vascular injuries, whether fasciotomy was needed, inappropriate intraoperative decisions, and injury severity score. Need for surgical reintervention, amputation, and death were defined as unfavorable outcomes. Univariate, bivariate, and logistic regression analyses were conducted.

Results

The sample comprised 94 patients; 83% were men; mean age was 30.8 years; combined arterial and venous injuries prevailed (57.5%); and superficial femoral vessels were the most affected (61.7%). Penetrating mechanisms prevailed (80.9%). Arterial injuries were most frequently treated with venous graft (59.6%) and venous injuries underwent ligation (81.4%). In 15% of cases, inappropriate surgical decisions were detected; most often use of the ipsilateral great saphenous vein for arterial reconstruction. Unfavorable outcomes occurred in 44.7%: surgical reintervention was necessary in 21.3% and limb amputation in 25.5%, while 9.5% of the patients died.

Conclusions

These injuries mainly involved young men, victims of gunshot wounds. Superficial femoral vessels were the most injured; concomitant non-vascular trauma was frequent, mainly fractures. Inappropriate surgical decisions increased the need for reinterventions by 34 times. Need for fasciotomy, presence of fracture/dislocation, blunt trauma mechanism, and popliteal artery injury increased the risk of amputation.

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.

[Acute therapeutic measures for limb salvage Part 1 : Haemorrhage control, emergency revascularization, compartment syndrome]

The primary care of Gustilo-Anderson type IIIC extremity injuries with relevant vessel lacerations is decisive for the success of a limb salvage procedure. This article shall present substantial emergency procedures for the salvage of the nutritive perfusion of a mangled extremity, based on the current literature. After provisory control of a peripheral haemorrhage (e. g. by manual pressure or tourniquet), an immediate decision must be made about the kind of emergency revascularization to be implemented as the limb salvage procedure. Here, the temporary intravascular shunt will be the fastest technique that can ensure a sufficient tissue perfusion in the case of vessel lacerations. Regarding the treatment of a fracture versus perfusion recovery, a shortening of ischemia time should have priority over fracture stabilization.If an acute compartment syndrome is suspected, a documented monitoring has to be performed in the limb salvage situation for 24 hours with clinical controls every 4 hours. Disproportional pain that does not respond to analgesics, and passive muscle stretching pain can be seen as cardinal symptoms. The positive predictive value of clinical findings is <15 %. During the observation period with an impending but not manifest compartment syndrome, an elevation of the extremity above heart level or its cooling are contraindicated. An intracompartmental pressure measurement is the most important instrument-based supplemental diagnostic method. The open fasciotomy of the affected compartments is the only causal therapy and should be performed as fast as possible. A decision against fasciotomy in cases of non-explicit clinical signs should not be made without a documented intracompartmental pressure measurement.

Venous Shunt Versus Venous Ligation for Vascular Damage Control: The Immunohistochemical Evidence

BACKGROUND

To evaluate the expression of immunohistochemical markers of tissue ischemia (iNOS, eNOS, and HSP70) in a vascular damage control experimental model to determine if a venous temporary vascular shunt insertion leads to a better limb perfusion when compared with the ligature of the injured vein.

METHODS

Experimental study in male Sus Scrofa weighting 40 Kg. Animals were distributed into 5 groups: group 1 animals were submitted to right external iliac artery (EIA) shunting and right external iliac vein (EIV) ligation; group 2 animals were submitted to right EIA shunting and right EIV shunting; group 3 animals were submitted to right EIV ligation; group 4 animals were submitted to right EIV shunting; group 5 animals were not submitted to vascular shunting or venous ligation. Transonic Systems flowmeters were used to measure vascular flow on right and left external iliac vessels, and i-STAT (Abbot) portable blood analyzer was used for EIVs blood biochemical analysis. An initial baseline register of invasive arterial pressure, iliac vessels flow, and venous blood analysis was performed. Arterial pressure and iliac vessels flow were taken immediately after right iliac vessels shunting or ligation. Then, hemorrhagic shock was induced by continuous 20 mL/min blood withdraw from the external right jugular vein whereas arterial blood pressure and iliac vessels flow registers were taken every 10 min, and blood samples from EIVs were obtained every 30 min until the vascular flow through right EIA (or through the shunt inserted into the right EIV for group 4 animals) became inexistent or until the animal's death. After the end of the experiments, bilateral hind limb's biopsies were obtained for immunohistochemical analysis. Using image editing and analysis software, the expression of iNOS, eNOS, and HSP70 (3 well-known ischemic associated immunohistochemical markers) was assessed. The mean expression of each marker in the right hind limb was compared between groups. For statistical analysis, Microsoft Office Excel 2007 and BioEstat 5.0 (2007) were used.

RESULTS

Immunohistochemical analysis showed no difference regarding the iNOS expression; nevertheless, both eNOS and HSP70 expression were statistically more intense (P < 0.05) on group 1 (eNOS = 1.32; HSP70 = 15.05) than on group 2 (eNOS = 0.018; HSP70 = 8.56).

CONCLUSIONS

The higher expression of eNOS and HSP70 in the right hind limbs of group 1 animals (arterial shunt and venous ligature) than group 2 animals (arterial shunt and venous shunt) suggests that venous ligation is associated with more intense ischemic histological findings than venous shunting.