To the Editor:
A recent case report [1] omitted several pertinent [2-6] and misinterpreted our work [7]. In this case report, the addition of 20 micro g fentanyl to spinal anesthesia was promoted as the cause of respiratory depression. A study that directly investigated respiratory depressive effects of intrathecal fentanyl and spinal anesthesia was not mentioned [2]. This double-blind dose-response study reported virtually no change in ventilatory response to CO2 with the addition of <or=to25 micro g of spinal fentanyl.
The author criticized use of fentanyl for postoperative analgesia [1] and implied that our study recommended this practice [7]. We recommended addition of fentanyl to improve intraoperative spinal anesthesia, and clinical trials support our recommendation [3-5]. Neither our rationale nor findings from these trials were discussed in the case report.
There are at least 13 published clinical trials (via MEDLINE) examining the addition of fentanyl to spinal anesthesia in ambulatory surgical [3], general surgical [4], obstetrical [5], and geriatric patients [6]. None of these studies noted an increased incidence of respiratory depression with the addition of fentanyl. None of these trials were discussed in the case report. We recommend that a balanced review of the literature be presented to aid interpretation of anecdotal experience.
Spencer S. Liu, MD
Joseph M. Neal, MD
Julia E. Pollock, MD
Hugh W. Allen, MD
Michael F. Mulroy, MD
Department of Anesthesiology; Virginia Mason Medical Center; Seattle, WA 98111
REFERENCES
1. Cornish PB. Respiratory arrest after spinal anesthesia with lidocaine and fentanyl. Anesth Analg 1997;84:1387-8.
2. Varrassi G, Celleno D, Capogna G, et al. Ventilatory effects of subarachnoid fentanyl in the elderly. Anaesthesia 1992;47:558-62.
3. Vaghadia H, Mcleod DH, Mitchell GW, et al. Small-dose hypobaric lidocaine-fentanyl spinal anesthesia for short duration outpatient laparoscopy. I. A randomized comparison with conventional dose hyperbaric lidocaine. Anesth Analg 1997;84:59-64.
4. Singh H, Yang J, Thornton K, Giesecke AH. Intrathecal fentanyl prolongs bupivacaine spinal block. Can J Anaesth 1995;42:987-91.
5. Belzarena SD. Clinical effects of intrathecally administered fentanyl in patients undergoing cesarean section. Anesth Analg 1992;74:653-7.
6. Fernandez-Galinski D, Rue M, Moral V, et al. Spinal anesthesia with bupivacaine and fentanyl in geriatric patients. Anesth Analg 1996;83:537-41.
7. Liu S, Chiu AA, Carpenter RL, et al. Fentanyl prolongs lidocaine spinal anesthesia without prolonging recovery. Anesth Analg 1995;80:730-4.
