Sedation in patients with acute or chronic respiratory disease needing ventilatory support is provocative. Agitation, anxiety and pain interfere with the measures to alleviate respiratory failure and to improve gas exchanges (invasive or non-invasive ventilation), while most sedatives and analgetics are respiratory depressants. Benzodiazepines, propofol and opioids are widely used, but it does not exist a consensus in medication selection, sedation and pain score scales recommended, implementation of protocols of sedation and recovery from the drugs administrated. The use of old and new sedative/analgesic medication, frequently combined, generates the need for understanding pharmacological interferences and for a strategy in preventing oversedation. Creating a specific protocol and guidelines in each respiratory ICU for sedation/analgesia in mechanically ventilated patients can improve outcome and reduce the ICU and hospital stay.