Gianluca Cappelleri

To the Editor: T hank you to Dr. Brull for his comments regarding 2 recent trials published in Regional Anesthesia and Pain Medicine by Wagener et al and Cappelleri et al, which delve into the existing gap in regional anesthesia literature regarding the role of sciatic nerve block (SNB) in analgesia and outcome after total knee arthroplasty (TKA). Because of the frequency of TKA operations (500,000 cases annually in the United States alone), improving analgesia after major knee surgery represents an important challenge for regional anesthetists. Recently, several authors have studied the role of either single or continuous SNB after TKA; there seems to be a lack of evidence that SNB provides additional analgesia or any recovery benefit. Nevertheless, ‘‘the absence of evidence does not equate to evidence of absence.’’ In fact, in clinical practice, many patients complain of pain after TKA, although a femoral catheter has been correctly positioned. I agree with Dr. Brull that the true analgesic role of SNB in TKA remains undefined and that the valid and definitive answer awaits the ideal study design. He suggests ‘‘a rigorous double-blinded, randomized trial that uses a combination of continuous femoral/lumbar plexus and placebo sciatic catheters with staged activation according to the source of pain.’’ Unfortunately, in that ‘‘ideal’’ trial, the difference between treatment and placebo could be wide enough to unmask the study blinding. In our double-blinded trial, all patients received a single SNB, then 1 group received an infusion of local anesthetic (0.06% levobupivacaine 7Y10 mL/kg) through the sciatic catheter, whereas the other group received a placebo infusion. At our surgeon’s request, we injected the sciatic catheter in all patients after sciatic nerve damage had been ruled out immediately after surgery. Nevertheless, all patients complained of severe pain (visual analog scale score 9 7) before SNB, despite well-functioning lumbar plexus catheters. For this reason, we did not include a third group with lumbar plexus plus placebo-sciatic block plus placebo sciatic infusion. To perform the ‘‘ideal’’ study design, we should be able to distinguish all sources of pain after TKA. Ben-David et al have been able to block separately the anterior region of the knee (by continuous femoral nerve block) and the posterior region (by continuous SNB). In fact, they activated the sciatic infusion when the patient had pain despite a well-functioning femoral catheter. In patients with both sciatic and femoral infusions, they demonstrated lower visual analog scale scores, although no patient was totally free from pain. The explanation for this pain has been the absence of a reliable obturator nerve block. Two previous studies have demonstrated that adding the obturator nerve block to the femoral nerve block, alone or in combination with SNB, improves postoperative relief after TKA. In our ‘‘ideal’’ study design, if we add sciatic nerve infusion to a criterion standard femoral block with staged activation according to the source of pain, some patients may still require rescue because of absent obturator nerve block. Lumbar plexus block provides a reliable obturator nerve block. But unfortunately, the literature does not support the hypothesis that continuous lumbar plexus block offers any benefit compared with continuous femoral nerve block in postoperative analgesia after TKA, and further head-to-head comparisons are needed. Having patients totally free from pain after TKA might lead to the improvement of the outcome or shorten hospital length of stay. In the trial by Wagener et al, the group of patients with a continuous SNB had significantly lower pain in the first 24 hours, but they were not discharged earlier. After 4 days, all patients showed a range of motion of 80 degrees and were able to walk at least 25 meters with no difference between groups. In contrast, in our study, patients with continuous SNB plus LPB showed a significantly improved range of motion (100 vs 60 degrees in patients receiving single SNB) and a longer walking distance (average distance of 31 vs 20 meters only 2 days after surgery). Unfortunately, our double-blinded trial was not designed to detect readiness for discharge. In conclusion, the 2 studies have provided meaningful information, with small differences in study design. To definitively answer the question of whether SNB improves postoperative outcome after TKA, future studies should be larger and should distinguish among all sources of pain involving TKA, with a rigorous method to determine whether adding SNB can improve the outcome, such as shortening the hospital length of stay.

The laryngeal mask airway (LMA) has been widely studied for both conventional and nonconventional uses, while the literature on the cuffed oropharyngeal airway (COPA) is still limited. The purpose of this manuscript was to review the initial appraisal of efficacy, safety, effects on hemodynamics and respiratory function, induction agents and drug requirements of this new supraglottic device. We reviewed main results of studies recently published on peer reviewed journals concerning the clinical uses of COPA. When used in healthy adults undergoing general anesthesia for routine minor procedures, the COPA and LMA are substantially equivalent. The LMA is associated with a higher first-time placement rate and fewer manipulations during usage, but the incidence of airway untoward events during COPA anesthesia is equivalent to that reported when using an LMA. The quality of breathing and capnography during COPA ventilation is similar to that provided by the LMA ventilation, with clinically relevant decrease in the physiological deadspace/tidal volume ratio and arterial to end-tidal CO2 tension difference compared with facemask ventilation. In selected patients without risk factors for regurgitation of gastric content, positive-pressure ventilation is similarly successful and safe with the COPA as with the LMA. The COPA seems to be less stimulating than LMA because it has been demonstrated to cause a lower incidence of pharyngeal trauma and sore throat in the immediate postoperative period, requires shorter exposure to an inhalational anesthetic and lower concentrations of propofol to be successfully placed, and is associated with lower effects on the patient's hemodynamic homeostasis than LMA. More extensive clinical evaluations should be advocated to better understand the risk/benefit ratio of this new supraglottic device; however, it may be concluded that in healthy adults receiving general anesthesia for short procedures the COPA allows for an effective and safe control of the patient's airway and ventilation.

To evaluate if the speed of intrathecal injection affects the lateral distribution of spinal block during unilateral spinal anaesthesia with 1% hyperbaric bupivacaine. Design: prospective, randomized, double-blind study. Setting: anaesthesia Department at a University Hospital. Patients: 30 ASA physical status I-II patients, scheduled for elective orthopedic surgery involving one lower limb only (ankle and foot surgery). Interventions: after placing the patients in the lateral decubitus position with the site to be operated on dependent, dural puncture was performed at L3-L4 interspace using a 25-Gauge Whitacre spinal needle. After the needle hole had been turned toward the dependent side, patients were randomized to receive 8 mg of 1% hyperbaric bupivacaine injected over either 40 sec (Group SLOW, n = 15) or 3 sec (Group FAST, n = 15). The lateral position was maintained for 15 min. Measurements: a blind observer evaluated the evolution of sensory (pinprick test) and motor (modifie...

The aim of this study was to compare efficacy, efficiency and surgeon's satisfaction of total intravenous anesthesia with propofol and remifentanil with those of spinal or peripheral nerve blocks for outpatient knee arthroscopy. One hundred and twenty patients undergoing elective outpatient knee arthroscopy were randomly allocated to receive total intravenous anesthesia with propofol and remifentanil (40), combined sciatic-femoral nerve block (40), or spinal anesthesia (40). Preparation times, surgeon's satisfaction, and discharge times with the 3 anesthesia techniques were measured. Anesthesia-related costs were also compared based on costs of drugs, disposable materials, and anesthesia and nurse staff. Preparation time was 13 min (8-22 min) with general anesthesia, 15 min (5-30 min) with spinal anesthesia and 15 min (5-25 min) with sciatic-femoral blocks (p=0.006). Surgeon's satisfaction was similar in the 3 groups, but 17 patients receiving peripheral nerve block (42%...

To evaluate the time required to achieve surgical block and fulfill standardized discharge criteria in outpatients receiving knee arthroscopy with either unilateral spinal anesthesia or combined sciatic-femoral nerve block. After a standard midazolam/ketoprofen premedication and baseline measurement of cardiovascular parameters, 50 ASA physical status I-II patients scheduled for elective outpatient knee arthroscopy were randomized to receive unilateral spinal anesthesia with 8 mg of 0.5% hyperbaric bupivacaine injected without barbotage through a 25-gauge Whitacre spinal needle (group USA, n = 25), or combined sciatic-femoral nerve block with 25 ml of 2% mepivacaine (15 ml for femoral nerve block and 10 ml for sciatic nerve block) (group SFNB, n = 25). Times from local anesthetic injection to achievement of surgical block defined as the presence of adequate motor (complete motor blockade of the operated limb in the USA group and inability to move the ankle and the knee of the operat...

In 60 patients receiving elective hallux valgus repair, we compared the efficacy of continuous popliteal sciatic nerve block produced with 0.2% ropivacaine (n = 20), 0.2% levobupivacaine (n = 20), or 0.125% levobupivacaine (n = 20) infused with a patient-controlled system starting 3 h after a 30-mL bolus of the 0.5% concentration of the study drug and for 48 h (baseline infusion rate, 6 mL/h; incremental dose, 2 mL; lockout time, 15 min; maximum incremental doses per hour, 3). No differences were reported in the intraoperative efficacy of the nerve block. The degree of pain was similar in the three groups throughout the study period, both at rest and during motion. Total consumption of local anesthetic solution during the first 24 h was 148 mL (range, 144-228 mL) with 0.2% ropivacaine, 150 mL (range, 144-200 mL) with 0.2% levobupivacaine, and 148 mL (range, 144-164 mL) with 0.125% levobupivacaine (P = 0.59). The volume of local anesthetic consumed during the second postoperative day was 150 mL (range, 144-164 mL) with 0.2% ropivacaine, 154 mL (range, 144-176 mL) with 0.2% levobupivacaine, and 151 mL (range, 144-216 mL) with 0.125% levobupivacaine (P = 0.14). A smaller proportion of patients receiving 0.2% levobupivacaine showed complete recovery of foot motor function as compared with 0.2% ropivacaine and 0.125% levobupivacaine, both at 24 h (35% vs 85% and 95%; P = 0.0005) and at 48 h (60% vs 100% and 100%; P = 0.001). We conclude that sciatic infusion with both 0.125% and 0.2% levobupivacaine provides adequate postoperative analgesia after hallux valgus repair, clinically similar to that provided by 0.2% ropivacaine; however, the 0.125% concentration is preferred if early mobilization of the operated foot is required.