Sedation during regional anesthesia: inhalation versus intravenous.
OBJECTIVE
Sedation of patients either with or without regional anesthesia is discussed to ascertain sedation requirements in the two groups. The differences between 'monitored anesthesia care' and conscious sedation are defined. Several current and promising methods with which we can evaluate a patient's degree or level of sedation are assessed. Also noted are safety concerns regarding monitoring solutions for patients undergoing monitored anesthesia care. Well established techniques, including some which are decidedly 'low tech', are examined. Several routes of intravenous administration are discussed along with patient variables. Sevoflurane sedation is mentioned with regards to administration, advantages and drawbacks.


RESULTS
Several modalities have been studied for evaluation of a patient's level of sedation, some of which have little applicability in the operating room. Processed electroencephalographic monitoring has tremendous promise but is currently not reliable enough to assess sedation level. Sevoflurane has a role in sedation, providing the limitations are understood. One drawback of sevoflurane is its greater degree of disinhibition when compared with intravenous agents, necessitating conversion to general anesthesia.


CONCLUSIONS
Evaluating the degree of patient sedation is a need that technology has yet to meet. Several techniques have been tried in intensive care units but have little utility in the operating room. Utilization of processed electroencephalogram waveforms has the greatest potential but is of limited value at the present time. Sevoflurane is demonstrated to have a limited role in sedation but may prove useful in specific circumstances.
Helgeson
Lars E
LE
Department of Anesthesiology, Yale University, School of Medicine, New Haven, Conneticut 06443, USA. lars.helgeson@yale.edu