In Reply:—

We read with interest the comments from Dr. Wildsmith. We agree that many investigators have made important contributions to the mode of epidural infusion. A comparison between continuous infusion versus  bolus technique was reported in 1975.1Drs. Scott, Schweitzer, and Thorn used a pump to administer regular intermittent top-up doses 1982.2Doses were 6–10 ml local anesthetic every 2 h. Observations with the regimen included “the spread of nerve block was much wider than necessary.”

The fundamental difference we described is a much smaller volume of the local anesthetic and more frequent administration. Our technique delivers a mini-bolus of 1 ml local anesthetic every 20 min.3Compared with the large-volume, intermittent top-up technique described above, our method is closer to the continuous infusion technique. Like a continuous infusion, the incidence of hypotension or bradycardia is negligible with our technique. However, the quality of analgesia is superior. An analogy is a quiet beach where small waves repeatedly wet the sand. We believe our small, frequent-dose technique is a new and effective method of epidural analgesia.

*The University of Iowa Hospitals and Clinics, Iowa City, Iowa. uedak@gf6.so-net.ne.jpor kenichi-ueda@uiowa.edu

References

1.
Griffiths DP, Diamond AW, Cameron JD: Postoperative extradural analgesia following thoracic surgery: A feasibility study. Br J Anaesth 1975; 47:48–55
2.
Scott DB, Schweitzer S, Thorn J: Epidural block in postoperative pain relief. Reg Anesth 1982; 7:135–9
3.
Ueda K, Ueda W, Manabe M: A comparative study of sequential epidural bolus technique and continuous epidural infusion. Anesthesiology 2005; 103:126–9