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Open Access Research article

Monitoring sedation for bronchoscopy in mechanically ventilated patients by using the Ramsay sedation scale versus auditory-evoked potentials

Chien-Wei Hsu12*, Shu-Fen Sun23, Kuo-An Chu4, David Lin Lee24 and Kam-Fai Wong5

Author Affiliations

1 Intensive Care Unit, Department of Medicine, Kaohsiung Veterans General Hospital, 386 Ta-Chung First Road, Kaohsiung City 813, Taiwan

2 Medicine Department, School of Medicine, National Yang-Ming University, 155 sec.2 Linong Street, Taipei City 112, Taiwan

3 Department of Physical Medicine and Rehabilitation, Kaohsiung Veterans General Hospital, 386 Ta-Chung First Road, Kaohsiung City 813, Taiwan

4 Chest Medicine, Department of Medicine, Kaohsiung Veterans General Hospital, 386 Ta-Chung 1st Road, 813 Kaohsiung City, Taiwan

5 Institute of Statistics, National University of Kaohsiung, 700 Kaohsiung University Road, Nanzih District, Kaohsiung City 811, Taiwan

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BMC Pulmonary Medicine 2014, 14:15  doi:10.1186/1471-2466-14-15

Published: 6 February 2014



Appropriate sedation benefits patients by reducing the stress response, but it requires an appropriate method of assessment to adjust the dosage of sedatives. The aim of this study was to compare the difference in the sedation of mechanically ventilated patients undergoing flexible bronchoscopy (FB) monitored by auditory-evoked potentials (AEPs) or the Ramsay sedation scale (RSS).


In a prospective, randomized, controlled study, all patients who underwent FB with propofol sedation were monitored and their sedation adjusted. During FB, one group was monitored by AEP and another group was monitored by RSS. The propofol dosage was adjusted by the nursing staff during examination to maintain the Alaris AEP index (AAI) value between 25 and 40 in the AEP group and the RSS at 5 or 6 in the RSS group. Before FB and during FB, the AAI, heart rate (HR), and mean arterial pressure (MAP) were recorded every 5 min. The percentages of time at the sedation target and the propofol dosages were calculated.


Nineteen patients received AEP monitoring and 18 patients received RSS monitoring. The percentage of time at the sedation target during FB was significantly higher in the AEP monitoring group (51.3%; interquartile range [IQR], 47.0–63.5%) than in the RSS group (15.4%; IQR, 9.5–23.4%), (P < 0.001). During FB, the RSS group had a significantly higher AAI (P = 0.011), HR (P < 0.001), and MAP (P < 0.001) than the AEP group.


In mechanically ventilated patients undergoing FB, AEP monitoring resulted in less variation in AAI, HR, and MAP, and a higher percentage of time at the sedation target than RSS monitoring.

Trial registration NCT01448811.

Auditory-evoked potential; Bronchoscopy; Critical care; Ramsay sedation score; Sedation