Naloxone is a well-known, well-tolerated drug with an excellent safety profile over many decades of use. The formulation used in this trial holds market authorization. Care will be taken not to include opioid users in this study as naloxone would precipitate acute withdrawal. Also possible drug misusers will be excluded as well as people who have access to remifentanil and infusion equipment in their daily work, although the abuse potential of this highly specialised drug is minimal. By weighing syringes before and after discharge the reliability of the dose delivered will be confirmed.