A. A. B. Barros D'Sa

Endotoxaemia, the generation of the cytokines and their relationship to intramucosal acidosis of the sigmoid colon in elective abdominal aortic aneurysm repair

Ischaemia of the large bowel occasionally occurs following abdominal aortic aneurysm repair and may lead to multiple system organ failure (MSOF). Intramucosal acidosis of the sigmoid colon is a good indicator of sigmoid colonic ischaemia. Intramucosal pH of the sigmoid colon was measured using the silicone tonometer in 21 patients undergoing abdominal aortic aneurysmectomy. Samples were taken for plasma endotoxin, tumour necrosis factor (TNF) and interleukin-6 (IL-6) measurements preoperatively, half-hourly during the operation, 2-hourly for the next 12 h, 4-hourly for a further 48 h and 8-hourly thereafter until the fifth day. The intramucosal pH of the sigmoid colon fell to less than 7.00 peri-operatively in 10 patients, four of whom developed diarrhoea; in comparison, this did not occur in any of the 11 whose pH remained greater than 7.00 (p = 0.036). Higher peak concentrations of endotoxin, TNF and IL-6 were found in those patients whose intramucosal pH fell to less than 7.00 compared to those whose pH remained greater than 7.00 (mean +/- S.E.M. pg/ml, endotoxin = 112 +/- 24 vs. 58 +/- 6, p < 0.05; TNF = 26 +/- 8 vs. 7 +/- 2, p < 0.05; IL-6 = 213 +/- 59 vs. 87 +/- 12, p = 0.09). In the two patients who died, both from the group with pH level less than 7.00, concentrations of IL-6 were considerably higher than that in most of the other patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Outflow Resistance and Early Occlusion of Infrainguinal Bypass Grafts

Distal outflow vascular resistance (VR) has been measured intra-operatively during 67 infrainguinal bypass procedures to establish whether it might have a role as a predictive test for early graft thrombosis. The graft outflow was popliteal artery above the knee (48), popliteal artery distal to the knee (6) or a single calf vessel (13). VR was measured before anastomosis of the graft, calculated from the relationship between pressure and flow in the outflow artery during infusion of the patients own blood at a constant rate. VR was measured before and after vasodilation with papaverine. Primary graft patency at 30 days was documented. In the 10 limbs in which graft thrombosis occurred, VR was 1167 +/- 367 mPRU, significantly higher than VR in 57 limbs with a patent graft, 850 +/- 310 mPRU (P = 0.02, Mann-Whitney U test). After papaverine, VR was 823 +/- 368 mPRU in the limbs with a thrombosed graft, significantly higher than that of limbs with a patent graft, 463 +/- 211 mPRU (P = 0.001). VR appeared to show most promise as a predictor of early thrombosis in the group of femoro-tibial and femoro-peroneal grafts. In this group, the value of 800 mPRU after papaverine was 92% efficient and was 80% sensitive, 100% specific and had a predictive value of 100% for early thrombosis. Distal outflow VR is an important factor in early graft thrombosis and might have a practical application as a predictor of early thrombosis of femoro-distal bypass grafts.

The Rationale for Arterial and Venous Shunting in the Management of Limb Vascular Injuries

The duration of limb ischaemia following blunt or penetrating vascular injury is one of several factors influencing the incidence of compar tment syndromes, ischaemic contracture, muscle necrosis and amputation. These wide-ranging effects of arterial injury, haemorrhage and ischaemia emphasise the importance of speed in restoring flow. Despite all the advances made in the managemen t of vascular injuries through the main conflicts in recent decades, a small but measurable incidence of complications including amputat ion continues, mainly as a consequence of the complexity of the injury and the time taken to evacuate the victim to hospital. The rationale and importance of shunting injured limb arteries and veins can best be judged firstly by a clear understanding of the pathophysiological effects of vascular disruption, and secondly by an appreciation of the constraints and shortcomings in the customary management of vessel injuries. The effects of major vascular disruption are aggravated by hypovolaemic shock and this scenario may be further complicated by associated bone and major soft tissue injury. The acute impairment of tissue perfusion and the corresponding fall in tissue pO2 increase capillary permeability and exudation of fluid into the interstitial space creating high compartmental pressures which in turn elevate venous pressure to cause further exudation. Swollen muscle fibres confined within inelastic fascial compar tments offer resistance to arterial inflow, already attenuated by several factors such as the vasoconstrictive response to hypovolaemia, haematoma, concomitant vein injury and soft tissue damage. Robbed of any residual-blood supply the extremity undergoes widespread small vessel thrombosis. 1

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)

Combined arterial and venous intraluminal shunting in major trauma of the lower limb.

A road accident victim was admitted in shock with an injured lower limb virtually dismembered at mid-thigh level. The early use of intraluminal shunts bridging both femoral artery and vein permitted an unhurried but logical sequence of wound debridement, bone stabilisation and optimal vascular repair rendering fasciotomy unnecessary. This approach led to an uncomplicated survival of the limb with eventual return of function.

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)

Immediate heparinisation and surgery in the management of saddle embolism.

Twenty-six patients (age range 40-88 years) with saddle embolism, representing 11% of cases of peripheral embolism, were treated during an 8-year period. A proven intra-cardiac source, including atrial fibrillation and post-infarction mural thrombosis, was observed in 22 cases (85%). The ambiguities in the clinical presentation of saddle embolism were sometimes responsible for delayed recognition. On confirmation of the diagnosis an IV heparin regime was immediately commenced followed by surgery. Our practice of initiating treatment of saddle embolism with immediate systemic heparin infusion resembles that of Blaisdell et al. In contrast, we also advocate a policy of early surgical intervention. Bilateral trans-femoral explorations were undertaken in 21 cases and direct aorto-iliac procedures in five cases. Recurrent embolism occurred in 27% of cases despite postoperative anticoagulant therapy. An overall limb salvage rate of 88.5% was recorded. The postoperative mortality of 30% was accounted for by primary cardiac disease and multiple organ failure. The influence of multiple and recurrent embolism and cardiac instability on the eventual outcome is signifcant. A policy of early systemic heparin therapy and surgery in the management of saddle embolism, enhances limb survival and prevents renal failure.

Radionuclide angiography and surgery for familial bilateral chemodectomas

Carotid body tumours, or chemodectomas, can occur on both sides of the neck (5%), and this bilaterality increases sixfold (30%) where a familial pattern is evident. The known pathological behaviour of chemodectomas makes early recognition and management desirable, especially when an inherited predisposition can be anticipated. Difficulties in clinical diagnosis and the hazards of blind exploration have imposed a reliance on contrast angiography, which is a potentially dangerous procedure. The family tree of a patient with bilateral chemodectomas was traced and 28 individuals were studied using radionuclide angiography (99mTechnetium gluconate), a quick, safe technique with a high yield. Bilateral chemodectomas were observed in five siblings, establishing conclusively the existence of a dominant hereditary trait. Excision of newly discovered tumours was accomplished without complication. The techniques which permitted such a favourable surgical outcome are discussed, emphasising the view that these tumours are best dealt with by vascular surgeons.