 Sedation is an integral part of treatment in caring for the critically ill, ventilated patient. Adequate sedation has been found to reduce stress, promote relaxation, induce amnesia, improve the tolerance of ventilatory support, and generally assist nursing care. However, all the sedative agents produce significant side effects such as loss of consciousness, amnesia and haemodynamic instability. In view of the complex characteristics associated with sedative agents, it is important to systematically assess and evaluate their effectiveness in the clinical area. Two issues are important in determining the effective use of these agents. The first issue relates to the use of specific sedation scales to facilitate consistent interpretations among clinicians. The use of such scales is limited in Australia. The second issue relates to the practice of protocol-directed sedation. Despite support for decision-making tools to assist clinicians choice of sedative agents, few studies have evaluated their effectiveness. This research aims to compare the effectiveness of protocol-directed sedation management with traditional non protocol-directed practice in an Australian intensive care unit ICU. In many Australian ICUs, the bedside nurse titrates the mechanical ventilation and sedation administration in consultation with the medical staff, usually in an unstructured manner. 