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A Complete Block of the Knee Combines Both Sacral and Lumbar Plexus Blocks: In Response

Jankowski, Christopher J. MD; Horlocker, Terese T. MD

Letters to the Editor: Letters & Announcements

Assistant Professor of Anesthesiology

Professor of Anesthesiology, Mayo Clinic College of Medicine, Rochester, MN

We appreciate Dr. Souron’s interest in our study and welcome the opportunity to respond to his comments.

Dr. Souron questioned the efficacy of psoas compartment block and spinal anesthesia for outpatient knee arthroscopy due to the administration of intraoperative fentanyl and propofol. However, according to our methodology, a single 2–3 μg/kg fentanyl dose was administered prior to surgical incision (during block performance). In addition, intraoperative sedation was achieved with a propofol infusion of 10–50 μg/kg/min. If more than 50 μg/kg/min of propofol was required, the block was considered a failure (1). These doses are consistent with those administered during “conscious sedation” in which patients remain arousable to voice, with adequate spontaneous respiration and protective airway reflexes intact. Furthermore, in many institutions, including ours, it is a patient expectation that intraoperative sedation be provided.

The importance of adequate perioperative sedation during regional anesthesia should not be minimized. Fanelli et al. (2) reported that despite a 93% success rate for upper and lower peripheral techniques using a nerve stimulator, 26% would not request the same anesthetic procedure in the future, mainly because of discomfort during block placement. Patient acceptance was lowest among those undergoing a combined sciatic-femoral block. As a result, the authors advocated the use of analgesic medications during block performance (2). Conversely, with the use of conscious sedation as an adjunct to regional anesthesia, we found a high level of patient satisfaction.

We disagree that the use of sedation may have delayed ambulation and prolonged hospital stay in patients receiving regional anesthesia. If this were the case, one would expect that times to ambulation and discharge would be prolonged in patients receiving general anesthesia since they received the most “sedation.” However, we did not note a difference in these variables among the groups.

Dr. Souron also queried why complete unilateral anesthesia was not attempted through a combined sciaticpsoas technique. Although somewhat controversial, it has not been accepted that a sciatic block is required for postoperative analgesia following total knee replacement (3). Therefore, it is unlikely to be a critical component of anesthesia for a comparatively minor procedure such as knee arthroscopy.

It is important to note that our results may not be directly applicable to other institutions. The optimal technique for knee arthroscopy will depend upon surgical duration, patient expectations and preferences, and nursing practices. These must all be taken into consideration when selecting an anesthetic approach.

Christopher J. Jankowski, MD

Terese T. Horlocker, MD

Assistant Professor of Anesthesiology

Professor of Anesthesiology, Mayo Clinic College of Medicine, Rochester, MN

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1. Jankowski CJ, Hebl JR, Stuart MJ, et al. A comparison of psoas compartment block and spinal and general anesthesia for outpatient knee arthroscopy. Anesth Analg 2003;97:1003–9.
2. Fanelli G, Casati A, Garancini P, et al. Nerve stimulator and multiple injection technique for upper and lower limb blockade: failure rate, patient acceptance, and neurologic complications. Anesth Analg 1999;88:847–52.
3. Allen HW, Liu SS, Ware PD, et al. Peripheral nerve blocks improve analgesia after total knee replacement surgery. Anesth Analg 1998;87:93–7.
© 2004 International Anesthesia Research Society