[Ischaemia of the lower limbs: anaesthesia and intensive care].

OBJECTIVES

To appreciate the severity of a patient with acute limb ischaemia, to know how to manage these patients during the perioperative period.

DATA SOURCES

References were obtained from PubMed data bank (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi) using the following keywords: acute limb, ischaemia, prognosis, complications, rhabdomyolysis, hyperkalaemia, compartment syndrome, fasciotomy.

DATA SYNTHESIS

Ischaemia of the lower limbs is a medico-surgical emergency. The ischaemia implies a decrease of cellular energetic stocks and an increase in intracellular calcium. During reperfusion, the calcium paradox is exacerbated and ROS formation produces membrane damage. Tissue oedema and a local and general inflammatory syndrome occur. Clinical symptoms of acute ischaemia include pallor, pulselessness, decrease of temperature and pain. Occurrence of neurological symptoms is a sign of severity. Prognosis of patients relates directly to preexisting collateral circulation, aetiology of the occlusion (thrombosis vs embolus), duration of ischaemia, topography of the occlusion (severity of proximal occlusions as the acute aortic occlusion), and co-morbidity (renal failure, heart failure). The temperature of the ischaemic limb, quality of the downstream circulation, extension of the thrombus, arterial pressure and association to a venous thrombosis are other prognostic factors of lower limb ischaemia. The first treatment to be initiated is high doses of heparin. Once the diagnosis is made, the number of preoperative tests will be as small as possible because of the urgency of revascularization. Arteriography will be performed only when really needed and when its realization will not delay revascularization and will not alter the patient's prognosis. Where general anesthesia is required, the choice of anaesthetic agents will be based on their haemodynamic stability. During severe acute limb ischaemia, monitoring of invasive pressure is recommended, as well as regular dosages of potassium, arterial gases and CPK. Preoperatively in case of severe ischaemia, (proximal occlusion lasting more than 6 hours), preventive treatment, including controlled reperfusion with heparinized serum is indicated. Surveillance and prevention of a rhabdomyolysis and renal failure are imperative. Immediately after reperfusion, a dosage of potassium must be performed; moreover that hyperkalaemia is favoured by acidosis or renal failure. Postoperative haemodialysis is performed in case of hyperkalaemia or renal failure. Occurrence of compartment syndrome has to be checked and fasciotomy must be performed in case of a doubt on the microcirculation integrity.