Ischemic preconditioning of free muscle flaps: An experimental study

Leech Therapy Protects Free Flaps against Venous Congestion, Thrombus Formation, and Ischemia/Reperfusion Injury: Benefits, Complications, and Contradictions

The use of free cutaneous or myocutaneous flaps in some surgeries, especially in reconstructive surgeries, is routine and imperative; nevertheless, it is controversial because of fear of flap loss due to tissue congestion and partial or complete necrosis. Different mechanisms are discussed in this process, and based on the involved mechanisms, various agents and approaches are suggested for flap salvage. Among these agents and strategies, leech therapy (hirudotherapy) can be a valuable complementary treatment; however, in this way, full attention should be given to all beneficial and harmful aspects to reach the best results. This study included a literature review of the essential complications following free tissue transfer and explained the effects of leech therapy for the respective complications. Based on the review of the literature, the essential complications following free tissue transfer were (I) venous obstruction and congestion, (II) delay in blood flow reestablishment, (III) ischemia/reperfusion injuries, and (IV) thrombus formation. Leech therapy can protect free flaps against the mentioned complications as a complementary treatment. Leech therapy is an appropriate complement, however, not a definite approach for flap salvage. Therefore, in some patients, other alternative methods or even flap removal may be a better option.

Remote ischemic preconditioning enhances fracture healing

PURPOSE

We hypothesized that RIP accelerates fracture healing.

METHODS

Rats (n = 48) were used for the technique of ischemic preconditioning involved applying 35 min of intermittent pneumatic tourniquet for 7 cycles of 5 min each to the fractured hind limb.

RESULTS

We observed greater callus maturity in RIP group at first week after fracture when compared to controls (p < 0,0001). The serum MDA levels demonstrated statistically lower values at the RIP group at the first week after fracture; however, there were not significant differences at 3rd and 5th weeks (p = 0.0001, p = 0.725, p = 0.271, respectively).

CONCLUSIONS

Greater callus maturity was obtained in RIP group.

Effect of ischemia preconditioning and leech therapy on cutaneous pedicle flaps subjected to prolonged ischemia in a mouse model

We sought to determine the effect of ischemic preconditioning (IPC) and hirudotherapy (leech therapy) on cutaneous pedicle flaps after they underwent prolonged ischemia (global ischemia) in a mouse model. Twenty cutaneous pedicle flaps were elevated in 20 mice, and the animals were randomized into four groups: sham, control, IPC and leech (5 flaps in each group). Except in the sham group, all flaps were subjected to global ischemia for 5 h via pedicle clamping. The control group did not receive any treatment before or after global ischemia. In the IPC group, global ischemia was preceded by three 10-min episodes of ischemia, each followed by 10 min of reperfusion. In the leech therapy group, after global ischemia, hirudotherapy was performed. Flap survival area and histopathological changes were evaluated on the 10th day after surgery. Flap survival areas were significantly higher in both the IPC and leech groups than in the control group and were significantly higher in the leech group than in the IPC group (p < 0.05). In conclusion IPC and hirudotherapy had definite effects on the survival area of cutaneous pedicle flaps that underwent prolonged ischemia in a mouse model.

Arterial injuries at the elbow carry a high risk of muscle necrosis and warrant urgent revascularisation

INTRODUCTION

Revascularisation following axial arterial system injury is effective in upper limb salvage but necrosis of muscle, the tissue most sensitive to ischaemia, may still occur. We examined the frequency of necrosis, its related factors and its functional significance.

METHODS

The clinical findings and operative management of 13 patients with injuries at the elbow referred to 2 plastic surgical hand surgery units over a 30-month period were reviewed. Good outcome was defined as minimal impairment with return to previous occupation, intermediate outcome as moderate impairment with change in occupation and poor outcome as major functional loss preventing work.

RESULTS

Seven patients injured the brachial and six injured both the radial and ulnar arteries. Concomitant injuries were severe with nerve injuries in 11 and muscle damage in 12 patients. Functional outcome was good in four cases, intermediate in four and poor in five. Muscle necrosis developed in four brachial artery injuries. In all four cases, initial successful revascularisation failed post-operatively. Case review revealed delayed recognition in three cases where pain heralded ischaemia but distal skin circulation and pulses were adequate. Of patients with necrosis, three had a poor outcome and one had an intermediate outcome.

CONCLUSIONS

The risk of muscle necrosis must be considered when managing these injuries, particularly if initial revascularisation is unsuccessful. Every effort should be made to optimise repair technique and post-operative monitoring. Limb salvage is no longer enough. Fully viable muscle is necessary to restore function and livelihoods.

Vascular clamping in liver surgery: physiology, indications and techniques

This article reviews the historical evolution of hepatic vascular clamping and their indications. The anatomic basis for partial and complete vascular clamping will be discussed, as will the rationales of continuous and intermittent vascular clamping.

Specific techniques discussed and described include inflow clamping (Pringle maneuver, extra-hepatic selective clamping and intraglissonian clamping) and outflow clamping (total vascular exclusion, hepatic vascular exclusion with preservation of caval flow). The fundamental role of a low Central Venous Pressure during open and laparoscopic hepatectomy is described, as is the difference in their intra-operative measurements. The biological basis for ischemic preconditioning will be elucidated. Although the potential dangers of vascular clamping and the development of modern coagulation devices question the need for systemic clamping; the pre-operative factors and unforseen intra-operative events that mandate the use of hepatic vascular clamping will be highlighted.

Ischemic pre-conditioning in deceased donor liver transplantation: a prospective randomized clinical trial

To assess the immediate and long-term effects of ischemic preconditioning (IPC) in deceased donor. liver transplantation (LT), we designed a prospective, randomized controlled trial involving 60 donors: control group (CTL, n = 30) or study group (IPC, n = 30). IPC was induced by 10-min hiliar clamping immediately before recovery of organs. Clinical data and blood and liver samples were obtained in the donor and in the recipient for measurements. IPC significantly improved biochemical markers of liver cell function such as uric acid, hyaluronic acid and Hypoxia-Induced Factor-1 alpha (HIF-1 alpha) levels. Moreover, the degree of apoptosis was significantly lower in the IPC group. On clinical basis, IPC significantly improved the serum aspartate aminotransferase (AST) levels and reduced the need for reoperation in the postoperative period. Moreover, the incidence of primary nonfunction (PNF) was lower in the IPC group, but did not achieve statistical significance. We conclude that 10-min IPC protects against I/R injury in deceased donor LT.

Ischaemia and reperfusion effects on skeletal muscle tissue: morphological and histochemical studies

This was a study on the oxidative stress due to ischaemia (I) and reperfusion (R) in skeletal muscle tissue. Using a tourniquet, groups of rats were submitted to ischaemia for 4 h, followed by different reperfusion periods. The animals were divided in four groups: control; 4 h of ischaemia (IR); 4 h of ischaemia plus 1 h reperfusion (IR-1 h); 4 h of ischaemia plus 24 h reperfusion (IR-24 h); and 4 h of ischaemia plus 72 h reperfusion (IR-72 h). At the end of the procedures, samples of soleus muscle were collected and frozen in n-hexane at -70 degrees C. Cryostat sections were submitted to haematoxylin-eosin, succinate dehydrogenase (SDH) and nicotinamide adenine dinucleotide-tetrazolium reductase (NADH-TR) stains. An additional muscle sample was processed for electron microscopy. No alterations were found in control animals. IR group showed fibres had normal aspect besides some round, acidophilic and hypertrophic fibres. There were several fibres with angular outlines and smaller diameters in this group compared with control group. NADH-TR/SDH reaction was moderately intense in most fibres. In some fibres, cytoplasm showed areas without activity and other fibres had very intense reactivity. IR-1 h group showed oedema hypercontracted fibres with disorganized myofibrils, mitochondria with focal lesions and dilated sarcoplasmic reticulum. NADH-TR/SDH reaction was moderate to weak. IR-24 h showed intense inflammatory infiltrate in the endomysium and perimysium. NADH-TR/SDH reaction was similar to IR-1 h. IR-72 h showed necrotic fibres, areas with inflammatory infiltrate, reduced muscle fibres at different stages of necrosis and phagocytosis, and many small round and basophilic fibres characterizing a regeneration process. NADH-TR/SDH reaction was weak to negative. Our results suggest that ischaemia and the subsequent 1-, 24- and 72-h reperfusions induced progressive histological damage. Although progressive, it may be reversible because there were ultrastructural signs of recovery after 72-h reperfusion. This recovery could in part be due to the low oxidative stress identified by the morphological and histochemical analysis.

Ischemic preconditioning reduces the severity of ischemia-reperfusion injury of peripheral nerve in rats

Background and aim

Allow for protection of briefly ischemic tissues against the harmful effects of subsequent prolonged ischemia is a phenomennon called as Ischemic Preconditioning (IP). IP has not been studied in ischemia-reperfusion (I/R) model of peripheral nerve before. We aimed to study the effects of acute IP on I/R injury of peripheral nerve in rats.

Method

70 adult male rats were randomly divided into 5 groups in part 1 experimentation and 3 groups in part 2 experimentation. A rat model of severe nerve ischemia which was produced by tying iliac arteries and all idenfiable anastomotic vessels with a silk suture (6-0) was used to study the effects of I/R and IP on nerve biochemistry. The suture technique used was a slip-knot technique for rapid release at time of reperfusion in the study. Cytoplasmic vacuolar degeneration was also histopathologically evaluated by light microscopic examination in sciatic nerves of rats at 7th day in part 2 study.

Results

3 hours of Reperfusion resulted in an increase in nerve malondialdehyde levels when compared with ischemia and non-ischemia groups (p < 0.001 and p < 0.0001 respectively). IP had significantly lower nerve MDA levels than 3 h reperfusion group (p < 0.001). The differences between ischemic, IP and non-ischemic control groups were not significant (p > 0.05). There was also a significant decrease in vacoular degeneration of sciatic nerves in IP group than I/R group (p < 0.05).

Conclusion

IP reduces the severity of I/R injury in peripheral nerve as shown by reduced tissue MDA levels at 3 th hour of reperfusion and axonal vacoulization at 7 th postischemic day.