Background and objective To test the hypothesis that magnesium sulphate reduces the amount of remifentanil needed for general anaesthesia in combination with propofol and mivacurium, we studied 50 patients undergoing elective pars plana vitrectomy in a double-blind, randomized prospective fashion. Methods Magnesium sulphate (50 mg kg ±1 body weight) or placebo (equal volume of NaCl) was given slowly intravenously after induction of anaesthesia with propofol 1±2 mg kg ±1 . Anaesthesia was maintained with propofol (using electroencephalographic control), mivacurium (according to train-of-four monitoring of neuromuscular blockade) and remifentanil (according to heart rate and arterial pressure). Results We observed a signi®cant reduction in remifentanil consumption from 0.14 to 0.09 lg kg ±1 min ±1 (P < 0.01). Mivacurium consumption was also markedly reduced from 0.01 to 0.008 mg kg ±1 min ±1 (P < 0.01), whereas propofol consumption remained

We can recommend the use of magnesium sulphate as a safe and cost-effective supplement to a general anaesthetic regimen with propofol, remifentanil and mivacurium, although we cannot clearly distinguish between a mechanism as a (co)analgesic agent at the NMDA-receptor site or its properties as a sympatholytic. The effect of a single bolus dose of 50 mg kg(-1) on induction lasts for about 2 h. For longer cases, either a continuous infusion or repeated bolus doses might be necessary.

Regional analgesia using single-injection regional blocks and continuous neuraxial and peripheral catheters can play a valuable role in a multimodal approach to pain management in the critically ill patient to achieve optimum patient comfort and to reduce physiologic and psychological stress. By avoiding high systemic doses of opioids, several complications like withdrawal syndrome, delirium, mental status changes, and gastrointestinal dysfunction can be reduced or minimized. Because of limited patient cooperation during placement and monitoring of continuous regional analgesia, indications for their use must be carefully chosen based on anatomy, clinical features of pain, coagulation status, and logistic circumstances. High-quality nursing care and well-trained physicians are essential prerequisites to use these techniques safely in the critical care environment.

Studies using more robust methods are necessary to define the rates of infection after different regional anesthesia procedures and to identify risk factors for infections. Data on risk factors would allow anesthesiologists to develop evidence-based guidelines for placement and care of catheters used for regional anesthesia. A multicenter surveillance system may help anesthesiologists address some of the unanswered questions and to develop evidence-based infection control recommendations.

Our observations indicate that clinical hypnosis may prevent nociceptive inputs from reaching the higher cortical structures responsible for pain perception. Whether the effects of hypnosis can be explained by increased activation of the left anterior cingulate cortex and the basal ganglia as part of a possible inhibitory pathway on pain perception remains speculative given the limitations of our study design.

Small-dose theophylline can be a useful alternative in the treatment of bradycardia in patients with spinal cord injury. In this series of three cases, I describe its successful use for this indication. In one case, initiation of theophylline treatment also increased respiratory drive and minute ventilation. A possible mechanism is that theophylline increases the force of contraction of diaphragmatic muscles because of enhancement of calcium uptake through an adenosine-mediated channel. The antibradycardiac effect is probably mediated through one or more different molecular mechanisms, which seem to be mediated by inhibition of phosphodiesterase 3.

Regional anesthesia and analgesia in the critically ill can help to improve respiratory function, bowel function, mental status and patient comfort secondary to its opioid-sparing effects. Limitations for the use of regional anesthetic techniques are mainly associated with bleeding risks, hemodynamic side-effects, difficulties in neurologic assessment and the potential of local anesthetic toxicity.

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