We read the letter of Gebhard et al. with great interest. Although we share some of the ideas stressed by the authors, we do not agree with several aspects of their statements.
Major orthopedic surgery may require prolonged postoperative analgesia. We were able to demonstrate the efficacy of repetitive subarachnoid sufentanil boluses for early postoperative pain relief via continuous microspinal catheters (continuous spinal anesthesia [CSA]) in our study. 1Although the study protocol ended after the fourth injection of sufentanil, longer and presumably sufficient pain relief would have been obtained with this concept. As we stated, subarachnoid sufentanil can lead to short-term respiratory depression. As a consequence, close monitoring remains mandatory in this setting, and we recommend that patients be kept in an intensive or intermediate care unit as long as subarachnoid opioids are administered. Because most of our patients undergoing total knee or hip replacement or revision arthroplasty are older than 65 yr, cardiocirculatory and respi-ratory comorbidities often require prolonged and extended postoperative surveillance per se . In addition, CSA offers several benefits in comparison with alternative techniques, such as epidural anesthesia or peripheral nerve blocks, especially in elderly patients undergoing major lower-limb surgery.
In comparison with epidural anesthesia, CSA provides better cardiovascular stability and more reliable blocks. 2In a study performed by Curatolo et al. , 39% of 1,051 patients with epidural anesthesia experienced pain during surgery. Moreover, the risk of epidural hematoma is lower in spinal when compared with epidural anesthesia, although it is extremely low (less than 1:150,000) for both techniques. 4
Disadvantages of sciatic–femoral nerve blocks were demonstrated by Fanelli et al. 5in patients undergoing lower-limb surgery. Despite a high success rate of 93% using a multiple puncture technique, only 71% of the patients would choose the same technique of regional anesthesia in the case of similar surgical interventions. In contrast, the success rate of CSA is nearly 100%, with a high acceptance by patients and surgeons. 6In addition, surgeons’ satisfaction with anesthetic techniques for joint replacement is mainly related to a complete muscle paralysis, which is more easily and perfectly achieved with spinal blocks rather than peripheral nerve blocks or epidurals. Both techniques, epidural anesthesia and combined sciatic–femoral nerve blocks, often require high cumulative doses of local anesthetics, thus increasing the risk of toxic side effects in compromised patients.
In terms of postoperative pain relief after major hip and knee surgery, we agree with Gebhard et al. that peripheral nerve blocks using catheter techniques provide adequate and even prolonged pain relief. However, the references cited by the authors seem to be most inappropriate to show safety and efficacy of these techniques because both references represent only case reports. 7,8
In summary, repetitive subarachnoid sufentanil boluses provide excellent and immediate pain relief after major lower-limb surgery without impairing motor function. The calculable risk of side effects can be minimized by surveillance; therefore, CSA with sufentanil for postoperative analgesia seems to be preferable in patients with comorbidities who require postoperative monitoring for medical reasons.