We appreciate the comments of Dr. Fry and are grateful for the opportunity to reply. Although we do perform retrobulbar blocks at our institution, all of our patients are sedated with propofol before block placement; therefore, we are not able to comment directly on Dr. Fry’s observation of sedation associated with retrobulbar block. As mentioned in our article, there have been three theories proposed for the mechanisms of sedation associated with spinal anesthesia: increased serum concentrations of local anesthetics, rostral spread of local anesthetics into the brain, and decreased afferent input from the spinal cord. Of these three theories, only a delayed rostral spread of the local anesthetic might reasonably account for the sedation we observed in our volunteer group 60 min after spinal anesthesia. As Dr. Fry mentions, given the proximity of the optic nerve to the cerebrospinal fluid, it is not inconceivable that a similar effect may be responsible for his observation of sedation after retrobulbar block.
Julia E. Pollock, M.D.*
Spencer S. Liu, M.D.
Joseph M. Neal, M.D.
© 2001 American Society of Anesthesiologists, Inc.