Background. Provision of preoperative information can alleviate patients' anxiety. However, the ideal method of delivering this information is unknown. Video information has been shown to reduce patients' anxiety, although little is known regarding the effect of preoperative multimedia information on anxiety in patients undergoing regional anaesthesia.Methods. We randomized 110 patients undergoing upper or lower limb surgery under regional anaesthesia into the study and control groups. The study group watched a short film (created by the authors) depicting the patient's in-hospital journey including either a spinal anaesthetic or a brachial plexus block. Patients' anxiety was assessed before and after the film and 1 h before and within 8 h after their operation, using the Spielberger state trait anxiety inventory and a visual analogue scale.Results. There was no difference in state and trait anxiety between the two groups at enrolment. Women had higher baseline state and trait anxiety than men (P¼0.02). Patients in the control group experienced an increase in state anxiety immediately before surgery (P,0.001), and patients in the film group were less anxious before operation than those in the control group (P¼0.04). After operation, there was a decrease in state anxiety from baseline in both groups, but patients in the film group were less anxious than the control group (P¼0.005).Conclusions. Preoperative multimedia information reduces the anxiety of patients undergoing surgery under regional anaesthesia. This type of information is easily delivered and can benefit many patients.

Preoxygenation had a substantial effect on the speed of early desaturation, but less effect on the time for SaO2 to decrease from 90 to 40%. Preoxygenation substantially delayed dangerous desaturation in all age groups, although the rapidity of denitrogenation in the very young (caused by the large ratio of minute ventilation to functional residual capacity) resulted in lengthy preoxygenation having little benefit over brief preoxygenation. Airway obstruction during apnoea accelerated every child's hypoxaemia through prevention of mass flow addition to oxygen stores and through intrathoracic depressurization. On average, haemoglobin desaturation from SaO2 90 to 40% was 33% min(-1) with an obstructed airway and 26% min(-1) with an open airway; all ages were similarly susceptible to this effect.

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SummaryIn this article, we will discuss the pathophysiology of peripheral nerve injury in anaesthetic practice, including factors which increase the susceptibility of nerves to damage. We will describe a practical and evidence-based approach to the management of suspected peripheral nerve injury and will go on to discuss major nerve injury patterns relating to intra-operative positioning and to peripheral nerve blockade. We will review the evidence surrounding particular strategies to reduce the incidence of peripheral nerve injury during nerve blockade, including nerve localisation methods, timing of blocks, needle techniques and design, injection pressure-monitoring and local anaesthetic and adjunct choice. Pathophysiology of peripheral nerve injuryPeripheral nerve injury during the peri-operative period can occur when a nerve is subjected to stretch, compression, hypoperfusion, direct trauma, exposure to neurotoxic material or a combination of these factors [1,2].In many cases, no clear aetiology for nerve injury is apparent [3,4]. The shared pathophysiological precipitant of these injuries is often nerve hypoperfusion and consequent ischaemia due to physical disruption of the vasa nervorum, intraneural haemorrhage and/or endoneural oedema [5]. These result in a spectrum of histological neural abnormalities ranging from impaired axoplasmic transport, axonal degeneration, Schwann cell damage, myelin destruction, segmental demyelination and complete Wallerian degeneration [6][7][8]. Depending on the severity and duration of the ischaemic insult, either temporary or permanent disruption to nerve impulse transmission can result. There is a loose relationship between the severity of the original pathophysiological mechanism, degree of nerve ischaemia and subsequent clinical presentation, although in an animal model of compression injury, the degree of histological nerve damage has been correlated with the degree and duration of compression [8].Established peripheral neuropathy, pre-existing (but subclinical) peripheral neuropathy, profound hypothermia, hypovolaemia, hypotension, hypoxaemia, electrolyte disorders, malnutrition, small or large body mass index (BMI), tobacco use and anatomical variants (such as the presence of cervical ribs) may increase the susceptibility of peripheral nerves to peri-

T he authors believe this is the first report of the successful use of lipid emulsion (Intralipid) in a prearrest situation and the first of cardiac arrhythmia and cardiovascular collapse following levobupivacaine administration in a peripheral nerve block. The 75-year-old ASA III woman presented for repair of a fractured femur, with a history of severe chronic obstructive pulmonary disease.With a normal preoperative electrocardiogram (ECG), a lumbar plexus block was begun at L4, after several unsuccessful attempts to place a subarachnoid block. Following negative aspiration, levobupivacaine 0.5% was injected slowly to a total of 20 mL; aspiration continued to be negative. Within seconds, the woman became unresponsive, followed by tonic-clonic convulsions, and a presumptive diagnosis of local anesthetic toxicity due to intravascular injection of levobupivacaine was made. Continuous, lead II ECG traces demonstrated deteriorating QRS morphology with reduced voltage and broadening complexes. Carotid pulse remained palpable and a second convulsion occurred 2 minutes after the first one. An intravenous bolus of metaraminol 0.5 mg was given and the airway secured with propofol and suxamethonium. Within 4 minutes of levobupivacaine injection, Intralipid 20% solution (100 mL) was infused over 5 minutes via the peripheral cannula, resulting in a rapid normalization of QRS morphology and no more convulsions. The patient's hemodynamics and ECG traces remained stable and surgery proceeded with volatile anesthesia. She continued to improve and the surgery was uneventful, as was recovery.Lipid emulsion has been used successfully to treat local anesthetic-induced cardiovascular collapse in animals and in 2 cases of cardiac arrest in humans. Cardiac arrest has been reported following intrathecal spread of local anesthetic during posterior lumbar plexus block and generalized tonic-clonic seizures have been seen in a 27-yearold patient following presumed intravenous injection of levobupivacaine, but with no ECG abnormalities or cardiovascular instability. There also have been reports of central nervous system toxicity and seizures following accidental intravascular injection of levobupivacaine. With reports of beneficial effects of Intralipid administration in local anesthetic toxicity, the authors have placed Intralipid in all theater areas for rapid accesses. They recommended continuing collection of reported uses of this lipid emulsion, both successful and unsuccessful, to reach a consensus on its efficacy and appropriateness.