Systemic and localised adverse effects of local anaesthetic drugs usually occur because of excessive dosage, rapid absorption or inadvertent intravascular injection. Small children are more prone than adults to methaemoglobinaemia, and the combination of sulfonamides and prilocaine, even when correctly administered, should be avoided in this age group. The incidence of true allergy to local anaesthetics is rare. All local anaesthetics can cause CNS toxicity and cardiovascular toxicity if their plasma concentrations are increased by accidental intravenous injection or an absolute overdose. Excitation of the CNS may be manifested by numbness of the tongue and perioral area, and restlessness, which may progress to seizures, respiratory failure and coma. Bupivacaine is the local anaesthetic most frequently associated with seizures. Treatment of CNS toxicity includes maintaining adequate ventilation and oxygenation, and controlling seizures with the administration of thiopental sodium or benzodiazepines. Cardiovascular toxicity generally begins after signs of CNS toxicity have occurred. Bupivacaine and etidocaine appear to be more cardiotoxic than most other commonly used local anaesthetics. Sudden onset of profound bradycardia and asystole during neuraxial blockade is of great concern and the mechanism(s) remains largely unknown. Treatment of cardiovascular toxicity depends on the severity of effects. Cardiac arrest caused by local anaesthetics should be treated with cardiopulmonary resuscitation procedures, but bupivacaine-induced dysrhythmias may be refractory to treatment. Many recent reports of permanent neurological complications involved patients who had received continuous spinal anaesthesia through a microcatheter. Injection of local anaesthetic through microcatheters and possibly small-gauge spinal needles results in poor CSF mixing and accumulation of high concentrations of local anaesthetic in the areas of the lumbosacral nerve roots. In contrast to bupivacaine, the hyperbaric lidocaine (lignocaine) formulation carries a substantial risk of neurotoxicity when given intrathecally. Drugs altering plasma cholinesterase activity have the potential to decrease hydrolysis of ester-type local anaesthetics. Drugs inhibiting hepatic microsomal enzymes, such as cimetidine, may allow the accumulation of unexpectedly high (possibly toxic) blood concentrations of lidocaine. Reduction of hepatic blood flow by drugs or hypotension will decrease the hepatic clearance of amide local anaesthetics. Special caution must be exercised in patients taking digoxin, calcium antagonists and/or beta-blockers.

Purpo~: To compare the efficacy of tramadol and morphine for intra-and postoperative analgesia in patients undergoing laparoscopic cholecystectomy. Methods: In a prospective, randomized, double-blind study 100 patients were allocated randomly into two groups. Ten minutes before induction of anaesthesia, patients in group I received 100 mg tramadol and those in group 2 Anaesthesia was induced with 5 mg.kg-thiopental and was maintained with 0 2, N20 received I0 mg morphine iv. plus isoflurane with additional doses of tramadol or morphine as decided by the attending anaesthetist. PostopeFatively, patients in group I and group 2 received tramadol and morphine, respectively, from a patient-controlled analgesia (PC.A) device. Pain, analgesic consumption, vital signs and side effects were recorded postoperatively for 24 hr. l~.~lts: Intraoperative consumption of tramadol and morphine were 137 _+ 37 and 12.2 + 3 mg, respectively. Compared with morphine, patients receiving tramadol had higher blood pressures and required greater mean ET~s o to control haemodynamic variables (P < 0.05). Postoperatively, there were no differences in observer pain score or wsual analogue pain score during the first 24 hr between groups except at 30, 45, and 90 min where patients in the tramadol group reported higher pain scores (P < 0.05). The cumulative, 24 hr PCA consumption was I 11 _+ 93 and 7.5 ---6.6 mg oftramadol and morphine, respectively. Condmiom: There was no difference between the use of tramadol and morphine to treat pain after laparoscopic cholecystectomy from 90 min after the end of surgery. Morphine was more effective than tramadol as an intraoperative analgesic.

Purpose: To evaluate the metabolic, hormonal and gastric fluid and pH changes after administration of a small volume of different preoperative feeding regimens.

Purpose: To evaluate the effects of tramadol administration at wound closure on postoperative pain and analgesic requirements in patients undergoing laparoscopic cholecystectomy.Methods: In a prospective, randomized, double-blind study 80 patients were allocated into two groups (n = 40 in each) to receive either 200 mg tramadol or placebo iv at the time of wound closure. Postoperatively, all patients received tramadol from a patient-controlled analgesia (PCA) device. Pain, analgesic consumption, vital signs and side effects were recorded postoperatively for 24 hr.Results: Administration of 200 mg tramadol at the time of wound closure was associated with a short-lived (60 min) reduction in pain scores and PCA consumption compared with placebo. Although the time to first request for analgesia after surgery was longer in patients who received tramadol at wound closure, there was no difference between the two groups with respect to pain scores or to the requirements of postoperative analgesia over the next 23 hr. The cumulative PCA consumption of tramadol in 24 hr was 139.4 ± 108 and 102.4 ± 106 mg in the placebo and tramadol groups, respectively (P = 0.06).