Lipid peroxidation and activity of antioxidant enzymes in muscle of the lower leg before and after arterial reconstruction

Epidural anesthesia may attenuate lipid peroxidation during aorto-femoral surgery

PURPOSE

To determine the effect of epidural anesthesia (EP) on oxygenation of the chronically ischemic limb in patients undergoing aorto-femoral bypass grafting and to assess whether it produces an alteration of lipid peroxidation and antioxidant status following revascularization.

METHODS

In this prospective, randomized, single-blinded study 40 ASA II or III patients undergoing elective aorto-femoral bypass grafting were allocated to receive general anesthesia (group GA, n = 20), or epidural + GA (group EP, n = 20) during surgery. Femoral venous blood-gas status, activities of the protecting antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GSH-px), glutathione reductase (GSH-rd), glutathione (GSH) and thiobarbituric acid-reactive substances (TBARS) as a marker of lipid peroxidation were determined in blood samples taken from the femoral vein at different intervals before and after revascularization.

RESULTS

Before the induction of anesthesia in group EP, femoral venous PO(2) [mean (standard deviation), 95% confidence interval] increased after achieving an adequate level of blockade by EP extending to the dermatomal level of T6-8 [29.32 (4.6), 26.34-32.30 to 36.29 (4.6), 33.37-39.22 mmHg, P < 0.05]. Femoral venous PO(2) was similar in both groups thereafter. In the GA group a significant increase in erythrocyte TBARS was observed immediately after restoration of blood flow when compared with baseline values [221.32 (102), 148.35-294-29 to 337.26 (123) 248.99-425.53 nmol*g(-1) hemoglobin, P < 0.01] but not at any other moment. In the EP group TBARS did not increase throughout the study. Within group comparisons revealed no significant differences in GSH, GSH-px, GSH-rd and SOD.

CONCLUSION

In patients with atherosclerotic aorto-iliac occlusive disease EP may possibly attenuate lipid peroxidation following revascularization but has no effect on antioxidant enzyme activities.

Lower limb oedema following distal arterial bypass grafting

Lower-limb oedema following arterial bypass surgery for ischemia is a common sequela which can complicate wound healing or delay resumption of mobility. Its exact pathogenesis remains uncertain but many theories have been proposed. Lymphatic disruption during arterial exposure, and endothelial damage from atrophy of the media and oxygen-derived free radical release are currently favoured hypotheses. Infrequently, deep vein thrombosis follows surgery and may exacerbate the condition. Efforts aimed at reducing the oedema, such as the use of lymphatic preserving incisional approaches or the use of antioxidants, have given conflicting results. The use of compression hosiery and leg elevation appear to be the most effective measures in reducing postoperative lower limb oedema.

Hypertonic saline infusion with or without dextran 70 in the reperfusion phase of experimental acute limb ischaemia

OBJECTIVES

To study the efficacy of hypertonic fluid therapy on central haemodynamics, leg blood flow, and skeletal muscle metabolism at reperfusion after subtotal bilateral limb ischaemia.

DESIGN

Prospective, randomised, controlled study, in pigs (n = 24).

METHODS

Bilateral limb ischaemia was induced (aortic balloon catheter) and central haemodynamics, peripheral blood flow-thoracic fluid content, blood chemistry, and skeletal muscle metabolite levels were monitored. After 235 min of ischaemia infusion of normal 0.9% saline (NS), hypertonic 7.5% saline (HS), or HS in 6% dextran 70 (HSD) was started. Five minutes later the aortic balloon was deflated and the haemodynamic and metabolic alterations were studied for 180 min after reflow.

RESULTS

Aortic occlusion resulted in haemodynamic alterations, reduced limb perfusion and metabolic changes indicative of tissue ischaemia. The haemodynamic support prior to, and following, deflation of the aortic balloon was more efficient for HS and HSD than for NS. Lactate clearance and restitution of high energy phosphagen levels in skeletal muscle were faster and more pronounced in the HS and HSD groups.

CONCLUSIONS

Small-volume hypertonic saline, especially in combination with 6% dextran 70, will effectively reverse limb ischaemia induced haemodynamic and tissue metabolic disturbances.

Antioxidative vitamin treatment: effect on lipid peroxidation and limb swelling after revascularization operations

The objective of this study was to evaluate the antioxidative properties of the multivitamin cocktail Omnibionta (alpha-tocopherol, ascorbic acid, retinol, vitamin B complex) in terms of diminishing lipid peroxidation with improvement of leg edema performance after limb revascularization operations in humans. Fifty-one subjects were selected; the control group contained 27 patients and the treatment group 24 patients, who received the vitamin cocktail intravenously before the start of reperfusion. All patients suffered from acute or chronic arterial occlusive disease, except two subjects with arterial trauma. MDA-TBARS in plasma, quantified by HPLC, taken as a measure of lipid peroxidation was significantly increased (p < 0.001) in the control group 1 hour after reperfusion onset and decreased to its baseline value within the following 2 hours (0.73 +/- 0.26, 1.21 +/- 0.48, 0.99 +/- 0.48, 0.73 +/- 0.33 nmol/ml). In contrast, in the treatment group MDA-TBARS did not exceed the baseline value during the reperfusion period (0.93 +/- 0.30, 0.70 +/- 0.29, 0.65 +/- 0.23, 0.70 +/- 0.37 nmol/ml). Leg edema, expressed by extremity circumference, was significantly (p < 0.008) elevated in the control group (30.7 +/- 4.04 cm versus 35.35 +/- 4.12 cm) compared to a lack of increase in the treatment group (29.25 +/- 5.13 cm versus 29.76 +/- 5.70 cm). These results suggest that antioxidative vitamin treatment might be valuable in preventing lipid peroxidation and decreasing extremity edema.

Reduction of free radical generation minimises lower limb swelling following femoropopliteal bypass surgery

Oxygen-derived free radicals have been implicated as contributors to the development of lower limb oedema observed after femoropopliteal bypass grafting. This study investigates the occurrence of free radical-induced lipid peroxidation after this operation and the possible effects of allopurinol (xanthine oxidase inhibitor) in reducing free radical injury in order to minimise lower leg oedema. Twenty-nine patients undergoing femoropopliteal bypass surgery were randomised in a double blind fashion into two groups; those in one were given allopurinol 200 mg orally (n = 15) at 24 h and 2 h preoperatively and again at 24 h postoperatively, while those in the second group received a placebo (n = 14). Daily lower limb volume was calculated to assess swelling. Blood samples were taken from the femoral vein for measurements of malondialdehyde (MDA), an end product of lipid peroxidation, before the application of the femoral artery clamp, just prior to and immediately after clamp release, and at 20 minute intervals thereafter for 1 hour. The increase in lower limb volume in the placebo group was almost twice (8.9 +/- 1.6%) that of the allopurinol group (4.6 +/- 1%; p = 0.02). Six out of the 14 patients receiving placebo suffered swelling of 10% or more of original lower limb volume in comparison to only one out of 15 in those given allopurinol (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Lipid peroxidation as a cause of lower limb swelling following femoro-popliteal bypass grafting

We examined the role of free radical induced lipid peroxidation in lower limb swelling in patients following femoro-popliteal bypass grafting. In 20 patients undergoing this operation blood samples were taken from the femoral vein via a cannula before the femoral artery clamp was applied, just prior to and immediately after clamp release and at 10 min intervals thereafter for 1 h for measurements of malondialdehyde (MDA) and vitamin E. The concentration of MDA was significantly elevated at 40 min after reperfusion (mean +/- S.E.M., 573 +/- 83 pmol/ml) compared to just before clamp release (359 +/- 41 pmol/ml; p < 0.01). This was associated with a corresponding fall in the concentration of vitamin E at the time of peak MDA rise (5.68 +/- 0.28 to 5.29 +/- 0.28 mumol/mM cholesterol, p < 0.05) suggesting its utilisation as an antioxidant. The degree of oedema was related to the changes in MDA and vitamin E. Thus, in the 15 patients with greater than 10% increase in lower limb volume the rise in the concentration of MDA was 364 +/- 44 to 693 +/- 76 pmol/ml (p = 0.0001) while that in the five, whose swelling was less than 10%, was 344 +/- 40 to 559 +/- 243 pmol/ml (p = 0.25). A significant fall in vitamin E was found only in the group with greater than 10% lower limb oedema (5.90 +/- 0.33 to 5.40 +/- 0.34 mumol/mM cholesterol, p < 0.01), in comparison to those with less than 10% swelling (5.01 +/- 0.35 to 5.04 +/- 0.50 mumol/mM cholesterol).(ABSTRACT TRUNCATED AT 250 WORDS)

Human plasma lipid peroxide levels show a strong transient increase after successful revascularization operations

This study was performed to evaluate the hypothesis that oxygen radicals/lipid peroxidation are involved in reperfusion injury in humans. The study included 37 patients, who underwent surgical revascularization operations for kidney transplantation (9 subjects) or limb salvage (28 subjects). Peripheral venous blood samples were taken 30 min before starting reperfusion (baseline) and 1, 2, 3, 4, and occasionally 6 to 18 h after revascularization. The amount of plasma malonaldehyde formed in the reaction with thiobarbituric acid (MDA-TBA) was determined by high-performance liquid chromatography (HPLC). The baseline MDA-TBA values of the patients were very close to the value determined for 20 age-matched healthy subjects (i.e. mean +/- SD 0.689 +/- 0.294 nmol/mL plasma [range 0.2 to 1.37] vs. 0.700 +/- 0.209 nmol/mL plasma [range 0.385 to 1.29]). All patients responded to successful revascularization with significant increase of the plasma MDA-TBA within about 1 h after onset of reperfusion. Thereafter the values decreased nearly to the preoperative state. The mean increase of MDA-TBA was 107% in kidney transplantation and 54% in limb revascularization. In a few patients with severe arteriosclerosis, revascularization was not optimal and no increase in the MDA-TBA value occurred. The results of this study indicate that therapeutic intervention to prevent lipid-peroxidation-mediated reperfusion injury is confined to a rather narrow time window and must be undertaken either prior to or immediately after revascularization.

Allopurinol--a free radical scavenger--reduces reperfusion injury in skeletal muscle

Reperfusion of ischaemic skeletal muscle may lead to increased vascular permeability, oedema and ultimately muscle necrosis. Oxygen-derived free radicals have been suggested as aetiological factors in reperfusion injury. Amputated rabbit hindlimbs were subjected to 4 h of ischaemia followed by 2 h or reperfusion with Krebs' buffer. One limb from each animal was reperfused with oxygen-saturated buffer (reoxygenated limb) while the other limb was reperfused with nitrogen-saturated buffer (non-reoxygenated limb). Six animals received allopurinol orally 2 days prior to the experiment and ten animals received no treatment. The energy charge dropped from 0.90 to 0.54 during ischaemia and increased to 0.82 after reperfusion with oxygenated perfusate. Oedema was determined by limb weight and water content in muscle biopsies and muscle injury was assessed by uptake of [Tc99]methylenediphosphonate ([Tc99]MDP). The results were expressed in ratios, between the reoxygenated and nonreoxygenated limb. Without allopurinol treatment, the increase in water content and limb weight in reoxygenated limbs exceeded (p less than 0.05) non-reoxygenated limbs (ratios = 1.73 and 1.89, respectively). Allopurinol treatment significantly reduced (p less than 0.05 and p less than 0.02, respectively) the increase in water content and limb weight (ratios = 0.54 and 1.01, respectively). Without treatment, [Tc99]MDP-uptake was greater (p less than 0.05) in reoxygenated limbs than in non-reoxygenated limbs (ratio = 1.60). Allopurinol treatment significantly reduced (p less than 0.002) [Tc99]MDP-uptake in reoxygenated limbs (ratio = 0.80). These results demonstrate that additional injury to ischaemic skeletal muscle occurs during reperfusion with oxygen.(ABSTRACT TRUNCATED AT 250 WORDS)