Effect of daily sedative interruption on sleep stages of mechanically ventilated patients receiving midazolam by infusion

Abstract

Daily sedative interruption (DSI) may reduce excessive sedation and shorten the duration of mechanical ventilation. It is not clear, however, how DSI affects sleep characteristics. For patients receiving mechanical ventilation, we compared the effect on sleep quality of DSI and continuous sedation (CS). Twenty-two mechanically ventilated patients who were receiving midazolam by infusion were randomly assigned to two groups, DSI (n = 11) or CS (n = 11). In the DSI group, sedatives were interrupted until the patients awoke and expressed discomfort, after which midazolam or opioids were administered intermittently as needed during the daytime (0600 to 2100 hours); during the night (2100 to 0600) midazolam was administered intravenously to maintain Ramsay sedation scale 4 to 5. In the CS group, the sedatives were titrated to obtain Ramsay sedation scale 4 to 5 throughout the day. The polysomnography of each patient was recorded continuously over a 24 hour period. Sleep stages were analysed using Rechtschaffen and Kales criteria. In the DSI group, the amount of stage 3 and 4 non-rapid eye movement sleep (slow wave sleep) was longer (6 vs 0 minutes, P = 0.04) and rapid eye movement sleep was longer than in CS (54 vs 0 minutes, P = 0.02). In the CS group, total sleep time during night-time was longer (8.7 vs 7.3 hours, P = 0.047) and frequency of arousal was lower (2.2 vs 4.4 event/hour, P = 0.03) than those in the DSI group. All mechanically ventilated patients demonstrated abnormal sleep architecture, but, compared with CS, DSI increased the amount of slow wave sleep and rapid eye movement sleep.