Letter to the Editor: In Response
We thank Drs. Pivalizza and Abramson for sharing their experience regarding the use of alfentanil in patients undergoing placement of retrobulbar block. They bring up two interesting points in their letter. First, the needle used for placement of all the blocks in our study was a 23-gauge Atkinson needle. This may account for the lower dose of alfentanil that they find effective in their patient population. The dose of alfentanil (20 micro gram/kg) that we used in our study was selected based upon our clinical experience here at the University of Utah using this needle. However, the absence of a dose-response curve is a major limitation of our study, as was noted in our Discussion section. To address this important question, we are presently conducting a study looking at the dose response to alfentanil and propofol. It is true that the older population is more sensitive to the respiratory and cardiovascular depressant effects of opioids, and, as we reported, one patient did develop significant respiratory depression. However, in our further clinical experience, this appears to be an uncommon and easily handled problem. Early awakening has not been a problem with this dose of alfentanil (20 micro gram/kg) because the vast majority of patients are alert and oriented during the placement of the block.
James B. Yee, MD, PhD
Department of Anesthesiology, The University of Utah, Salt Lake City, UT 84132