Hypothermic, Initially Oxygen-Free, Controlled Limb Reperfusion for Acute Limb Ischemia

[Ischemia-related compartment syndromes in vascular surgery]

Even after the endovascular revolution, acute compartment syndrome (CS) remains an important and frequently present differential diagnosis after many operations. Based on a qualitative review this article gives an overview of the most frequent forms of CS as well as some less frequent entities that require attention in the routine clinical practice. Additionally, the pathophysiology, diagnostics and treatment as well as current research topics for CS, especially concerning the lower leg, are dealt with in detail. In summary, nothing has essentially changed ever since the first description of CS in that the clinical estimation remains the gold standard. The detection and the adequate treatment especially of abdominal CS and CS of the lower leg remain a key competence of vascular surgeons.

Mechanisms and Interventions on Acute Lower Limb Ischemia/Reperfusion Injury: A Review and Insights from Cell to Clinical Investigations

AIM

This review aims to highlight mechanistic insights on skeletal muscle ischemia/reperfusion injury (IRI), a potentially life-threatening complication after acute lower limb ischemia. Lower limb IRI produces a wide spectrum of manifestations, ranging from local skeletal muscle necrosis to multi-organ failure. There is increasing evidence from both in vitro and in vivo reports to demonstrate several promising interventions that have successfully reduced IRI in skeletal muscle ischemic models. However, clinical studies to confirm their benefits are still lacking.

METHOD

We conducted a comprehensive search of English literature listed in the PubMed database (All related published articles shown in PubMed until September 2020 have been included in this review), using the following keywords: acute limb ischemia, acute arterial occlusion, compartment syndrome, ischemic reperfusion injury, revascularization and hypoxic reoxygenation.

RESULT

58 articles pertinent to acute limb ischemia models were identified. The underlying mechanisms associated with IRI in skeletal muscle are due to excessive mitochondrial production of reactive oxygen species (ROS), cellular apoptosis and activation of inflammatory cascades. Several therapeutic interventions including both pharmacological and non-pharmacological treatments have been investigated and some showed promising results. These interventions include antioxidation, anti-inflammation, anti-hypertension, controlled-reperfusion and ischemic preconditioning. Further clinical studies are needed to warrant their use in a clinical setting for lower limb IRI treatment.

CONCLUSION

This review comprehensively summarizes the mechanisms underlying IRI in lower limb ischemia. The reports currently available regarding the potential therapeutic interventions against lower limb IRI from in vitro, in vivo and clinical studies are presented and discussed. These findings may provide mechanistic insights for devising the strategies to improve the clinical outcomes in IRI patients in the near future. Further clinical studies are needed to warrant their use in a clinical setting for lower limb IRI treatment.

Postoperative extremity compartment syndrome in a cancer center: Incidence and risk factors

OBJECTIVE

Postoperative compartment syndrome is a reported complication with known patient- and treatment-specific risk factors. Cancer patients carry unique risk factors associated with their underlying disease and long, complex procedures. While elevated serum lactate in traumatic and intensive care settings portends higher risk, no laboratory parameter has demonstrated utility in postoperative risk stratification. Postoperative extremity compartment syndrome in the study institution's cancer population was examined and whether intraoperative serum lactate correlates with postoperative compartment syndrome risk was investigated.

METHODS

A 1:2 case-control study was performed, which compared cancer patients with postoperative compartment syndrome to those who underwent similar surgical procedures without this complication. Twelve patients were matched to 24 controls by sex, age, surgical procedures, and duration of surgery. Patient and operative variables were analyzed for prognostic significance.

RESULTS

The compartment syndrome rate was 0.09% of all cases (n = 13,491); 0.12% of cases ≥ 3 h' duration (n = 9,979), and 0.25% of cases ≥ 5 h (n = 4,811). Compared with controls, the case group had higher median BMI (31.7 kg/m2 vs. 25.4 kg/m2, P = 0.001), and median intraoperative lactate level (4.05 mmol/L vs. 1.5 mmol/L, P = 0.047).

CONCLUSION

Our institutional incidence of postoperative compartment syndrome was similar to that of non-oncologic institutions. While many traditional risk factors did not prove to be influential in our patients, elevated median body mass index and intraoperative serum lactate were identified as risk factors for postoperative compartment syndrome in a cancer population.

Which Distant Organ is Most Affected by Lower Extremity Ischemia-Reperfusion?

BACKGROUND

It has been experimentally shown that reperfusion injury occurs in many remote organs after ischemia-reperfusion (I/R) of the lower extremity. However, which distant organ is affected more after I/R of the lower extremity has not been investigated. In this study, we investigate which remote organ is predominantly affected after lower extremity I/R.

METHODS

Twenty male Sprague-Dawley rats were randomly divided into 2 groups: sham (group 1) and lower extremity I/R (group 2). In group 2, 1 hr of ischemia of the left lower extremity was followed by 24 hr of reperfusion of the limb. After reperfusion, the lung, liver, kidney, heart, and small intestine tissues were harvested in both groups.

RESULTS

In the I/R group, the malondialdehyde levels were significantly higher in the heart and small intestine tissues than those in other tissues (P < 0.05). In addition, in the I/R group, the glutathione and glutathione peroxidase activities were also higher in the heart tissues than those in other tissues (P < 0.05). However, these results were not significant because the malondialdehyde, glutathione, and glutathione peroxidase levels of the heart tissues in the control group were higher than those of the other tissues. Therefore, no statistically significant difference was found between the tissues in terms of the histological damage score we created and the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling-positive cell numbers.

CONCLUSIONS

There was no difference in the severity of reperfusion injury between the tissues we examined after lower extremity I/R. This suggests that every distal organ should be carefully monitored after lower extremity I/R.

The Protective Effects of Fasciotomy on Reperfusion Injury of Skeletal Muscle of Rabbits

The authors aim to investigate protective effects of fasciotomy against ischemia reperfusion injury of skeletal muscle in rabbit and to compare the treatment effects of prereperfusion + fasciotomy and fasciotomy + postreperfusion against ischemia reperfusion injury of skeletal muscle. 24 healthy male Japanese white rabbits were randomly divided into 3 groups, and 4 hours' ischemia was established in these rabbits through surgery. Six hours' reperfusion was performed in group A; reperfusion + postfasciotomy was performed in group B; and prefasciotomy + reperfusion was performed in group C. Result showed that prefasciotomy and postfasciotomy could protect skeletal muscle against ischemia reperfusion injury, reduced MDA (malondialdehyde) expression, MPO (myeloperoxidase) expression, and apoptosis of muscle in the reperfused areas, increased Bcl-2 expression, and decreased Bax expression. The MDA and MPO levels in group B and group C were significantly lower than those in group A, and MDA and MPO levels in group C were significantly lower than those in group B. Prefasciotomy and postfasciotomy could protect against ischemia reperfusion injury in skeletal muscle. The protective effects of prefasciotomy against ischemia reperfusion injury are better than postfasciotomy.

Acute limb ischemia: contemporary approach

Acute limb ischemia is a critical condition with high mortality and morbidity even after surgical or endovascular intervention. Early recognition is important, but a delayed presentation is not uncommon. Viability of the limb is assessed by motor and sensory function and with interrogating Doppler flow signals in pedal arteries and popliteal veins as categorized by Rutherford. Category IIa indicates mild-to-moderate threat to limb salvage over a time frame without revascularization. Limb ischemia is critical without prompt revascularization in category IIb. Because the risk of reperfusion injury is high in this group of patients, perioperative management is important. In category III, reperfusion is not indicated except for embolism within several hours of onset. Intimal injury should be avoided by careful tactile control of a balloon with a smaller size catheter and under radiographic monitoring. Adjunctive treatment with catheter-directed thrombolysis or bypass surgery is sometimes necessary. Endovascular treatment is a promising option for thrombotic occlusion of an atherosclerotic artery. Ischemia-reperfusion injury is a serious problem. Controlled reperfusion with low-pressure perfusion at a reduced temperature and use of a leukocyte filter should be considered. The initial reperfusate is hyperosmolar, hypocalcemic, slightly alkaline, and contains free radical scavengers such as allopurinol. Immediate hemodialysis is necessary for acute renal injury caused by myoglobinemia. Compartment syndrome should be managed with assessment of intra-compartment pressure and fasciotomy.