Bilobar atelectasis after difficult tracheal intubation

Abstract

SummaryWe describe the loss of function in the sciatic nerve after an uneventful sciatic nerve block using 25 ml of lignocaine 1% with adrenaline 1 in 200 000 in a patient receiving b blocker drugs. Lack of pain on injection and complete regeneration of the nerve after 12 months in a patient with severe peripheral vascular disease led us to postulate ischaemic nerve damage as a mechanism of injury. Adrenaline-induced unopposed a-mediated vasoconstriction in a b-blocked patient is suggested as a possible mechanism of peripheral nerve injury worthy of further investigation. Regional anaesthesia is widely used in orthopaedic surgery as it provides good operating conditions whilst having limited effects on the patient's cardiorespiratory physiology. In particular, regional anaesthesia is the method of choice for such surgery in patients with respiratory disease. The use of specific nerve blocks (e.g. sciatic, femoral) has additional advantages over regional techniques such as epidural and spinal anaesthesia in that the nerve blocks are not associated with autonomic blockade, thus making them suitable for use in patients with an element of cardiovascular disease. Techniques for such blocks are well known and are usually free of complications; however, nerve damage can occur. We describe a patient in whom an uneventful sciatic nerve block was associated with a loss of function relating to that nerve of 12 months duration. Case historyA 59-year-old woman was scheduled for the surgical removal of tibial fixation plates. Her medical history included controlled hypertension and chronic obstructive airways disease. She smoked 10 cigarettes per day and her medication included atenolol 100 mg per day, Dyazide (triamterine and hydrochlorothiazide) one tablet per day, salbutamol and Duovent (fenoterol and ipratroprium) inhalers. On admission, her blood pressure was 150/90 mmHg, pulse rate 55 beat.min -1 and there were no clinical signs of peripheral vascular disease. She reported a recent chest infection and it was decided to proceed with the surgery under regional anaesthesia.In the anaesthetic room, a 14G intravenous cannula was inserted in the dorsum of the patient's left hand; electrocardiogram, pulse oximeter and noninvasive blood pressure cuff were attached. No intravenous sedation or premedication was given to the patient at any stage. A sciatic nerve block was performed under aseptic conditions using the posterior approach of Labat [1] and a 100-mm insulated needle. Plantar flexion was elicited easily with a stimulating current of 0.25 mA. After careful intermittent aspiration, 25 ml of lignocaine 1% with adrenaline 1 in 200 000 was injected. There was no resistance to injection and no pain or paraesthesia was elicited either on approaching the nerve or on injection. In order to complete analgesia to the medial calf and produce analgesia for a thigh tourniquet, a femoral '3-in-1' block, again using a nerve stimulator, was performed as described by Winnie [2] using 20 ml of lignocaine 1% with adrenaline 1 in 200 000.