Sedation during mechanical ventilation in intensive care - Sedation practices and patients' memories, stressful experiences and psychological distress

Abstract: The overall aim of this thesis was to describe and determine intensive care sedation in adult mechanically ventilated patients with the emphasis on patients? memory, stressful experiences and psychological distress. The results are based on a nationwide postal survey (Paper I) including 89 Swedish intensive care units (ICUs) followed by a prospective cohort study (Papers II?IV) conducted over 18 months in 2 ICUs including 313 mechanically ventilated adults admitted for more than 24 hours. In Papers II?IV, the patients were interviewed 5 days and 2 months post ICU using established instruments concerning patients? memory, stressful experiences, anxiety, depression and acute posttraumatic stress disorder (PTSD) related symptoms. Patient characteristics, doses of sedatives and depth of sedation as measured by a scoring system during the ICU stay were collected from hospital records after the interviews. Sedation practices in Swedish ICUs in 2000 varied, with a preference for heavy sedation with little use of sedation guidelines and scoring systems, and indicated the need of research concerning patient comfort in relation to sedation. Among the 250 patients interviewed, amnesia of the ICU (18%) and of the endotracheal tube (54%) was associated with deeper levels of sedation, and long-term heavy sedation increased the risk of having delusional memories without factual recall. Bothersome stressful experiences of the ICU were common (68%) and associated with lighter levels of sedation by means of more periods of wakefulness, and with longer ICU stay. The lighter the sedation practised, the higher the probability of having recall and stressful memories of the ICU. The best predictor of delusional memories in general and of having bothersome nightmares was increasing length of ICU stay. Psychological distress 2 months post ICU was associated with experiences of the ICU perceived as extremely stressful, but not with amnesia or having delusional memories without factual recall of the ICU. Female sex, signs of agitation, administration of midazolam and feelings of extreme fear during the ICU stay, and high levels of anxiety 5 days post ICU, increased the risk of developing high levels of acute PTSD-related symptoms 2 months post ICU. In conclusion, the results of this thesis indicate that some ICUs presumably could benefit from reviewing their sedation practice. Regular sedation assessment should be a priority of all ICU staff and the use of sedatives adapted to the individual requirements of the patient. Having memories of the ICU appears to be common and long-term critically ill patients seem to need special attention and support due to the increased risk of having bothersome stressful experiences of the ICU and of the endotracheal tube. Efforts to reduce stressful memories and to facilitate care by sedating patients more deeply for a longer period of time may interfere with the chance of a rapid and complication-free recovery. Consequently, the ICU staff needs to consider non-pharmacological means of improving patient comfort in addition to sedation. Early follow-up visits at the general ward, including assessment of patients? subjective status, and further follow-up support services after hospital discharge may be beneficial for the patients. Due to limitations in study design and measurement quality further research is needed to confirm the associations suggested in this thesis.