Ali Shariat

Continuous interscalene block in patients having outpatient rotator cuff repair surgery: a prospective randomized trial.

BACKGROUND: We performed this randomized trial to compare the recovery profile of patients receiving single injection (SISB) and continuous interscalene brachial plexus block (CISB) or general anesthesia (GA) for arthroscopic rotator cuff repair surgery through the first postoperative week. Our primary hypothesis was that the highest pain numeric rating scale (NRS) (worst pain score) at the end of the study week would be lower for patients in the CISB group than for patients in the SISB or GA groups. METHODS: Seventy-one patients scheduled for elective outpatient arthroscopic rotator cuff repair were enrolled. CISB patients received 20 mL of 0.5% ropivacaine as a bolus through a catheter, whereas SISB patients received the same injection volume through a needle. CISB patients received an infusion of 0.2% ropivacaine at 5 mL/h with a patient-controlled bolus of 5 mL hourly for 48 hours. GA-only patients received a standardized general anesthetic. Postoperative highest NRS pain scores through the first postoperative week, time-to-first pain, analgesic consumption, fast-tracked postoperative anesthesia care unit (PACU) bypass rate, length of PACU stay, time-to-discharge home, total hours of sleep, and related adverse effects were recorded in the PACU and at home on postoperative days 1, 2, 3, and 7. RESULTS: No patient in the CISB or SISB groups reported a NRS ≥1 or required analgesics while in the PACU. While most patients in the CISB and SISB groups were fast-tracked to PACU discharge, no patient in the GA group was fast-tracked (&KHgr;2 P = 0.003). Length of stay in the PACU was significantly shorter for the CISB and SISB groups than for the GA group (20 ± 31, 30 ± 42, and 165 ± 118 minutes, respectively (CISB vs GA, P < 0.001; SISB vs GA, P <0.001), and time-to-discharge home was significantly shorter when compared with the GA group. Time to first pain report was longer in the CISB group. Mean NRS scores were lower for patients in the CISB group than in the SISB and GA groups on postoperative days 1 and 2, and use of narcotics (doses ≥1) was lower until postoperative day 3. Patients who received CISB slept significantly longer than patients who received SISB or GA (P < 0.01) during the first 48 hours postoperatively. By the end of the study week, 26% of patients in the CISB group, 83% in the SISB group, and 58% of GA patients reported NRS ≥4 (both P-values ⩽ 0.05). CONCLUSION: The analgesic benefits of CISB found in the PACU and immediately after discharge extend through the intermediate recovery period ending on postoperative day 7.

High-definition ultrasound imaging defines the paraneural sheath and the fascial compartments surrounding the sciatic nerve at the popliteal fossa.

Background and Objectives The connective tissue layers that surround the sciatic nerve at the popliteal fossa are poorly defined. We present high-definition ultrasound images of the sciatic nerve, which were acquired during ultrasound-guided popliteal sciatic nerve block (SNB), that clearly demonstrate these fascial layers. Methods Four patients undergoing hallux valgus surgery received an ultrasound-guided popliteal SNB using a high-definition ultrasound system. In the ultrasound images, the paraneural sheath was identified as a hyperechoeic fascial layer between the outer surface of the sciatic nerve (epineurium) and the epimysium of the surrounding muscles. The paraneural sheath was distinct from the epineurium, better delineated after the local anesthetic injection, and enveloped not only the sciatic nerve but also the common peroneal and tibial nerves separately. In the postblock sonograms, the local anesthetic was compartmentalized into 2 broad areas, that is, external (subepimyseal) and internal (subparaneural) to the paraneural sheath. The popliteal SNB was effective for surgical anesthesia in all 4 patients. Conclusions We have demonstrated the paraneural sheath and the fascial compartments, that is, the “subepimyseal perineural compartment” and the “subparaneural compartment” that surround the sciatic nerve and act as conduits for local anesthetic spread during a popliteal SNB.

The effect of mixing 1.5% mepivacaine and 0.5% bupivacaine on duration of analgesia and latency of block onset in ultrasound-guided interscalene block.

BACKGROUND:Short- and long-acting local anesthetics are commonly mixed to achieve nerve blocks with short onset and long duration. However, there is a paucity of data on advantages of such mixtures. We hypothesized that a mixture of mepivacaine and bupivacaine results in a faster onset than does bupivacaine and in a longer duration of blockade than does mepivacaine. METHODS:Sixty-four patients undergoing arthroscopic shoulder surgery (ages 18 to 65 years; ASA physical status I–II) with ultrasound-guided interscalene brachial plexus block as the sole anesthetic were studied. The subjects were randomized to receive 1 of 3 study solutions: 30 mL of mepivacaine 1.5%, 30 mL of bupivacaine 0.5%, or a mixture of 15 mL each of bupivacaine 0.5% and mepivacaine 1.5%. The block onset time and duration of motor and sensory block were assessed. RESULTS:Onset of sensory block in the axillary nerve distribution (superior trunk) was similar among the 3 groups (8.7 ± 4.3 minutes for mepivacaine, 10.0 ± 5.1 minutes for bupivacaine, and 11.3 ± 5.3 minutes for the combination group; P = 0.21 between all groups). The duration of motor block for the combination group (11.5 ± 4.7 hours) was between that of the bupivacaine (16.4 ± 9.4 hours) and mepivacaine (6.0 ± 4.2 hours) groups (P = 0.03 between bupivacaine and combination groups; P = 0.01 between mepivacaine and combination groups). Duration of analgesia was the shortest with mepivacaine (4.9 ± 2.4 hours), longest with bupivacaine (14.0 ± 6.2 hours), and intermediate with the combination group (10.3 ± 4.9 hours) (P < 0.001 for mepivacaine vs. combination group; P = 0.01 for bupivacaine vs. combination group). CONCLUSIONS:For ultrasound-guided interscalene block, a combination of mepivacaine 1.5% and bupivacaine 0.5% results in a block onset similar to either local anesthetic alone. The mean duration of blockade with a mepivacaine–bupivacaine mixture was significantly longer than block with mepivacaine 1.5% alone but significantly shorter than the block with bupivacaine 0.5% alone.

Fascia lliaca block for analgesia after hip arthroplasty: a randomized double-blind, placebo-controlled trial.

Background and Objectives Fascia iliaca block (FIB) is often used to treat pain after total hip arthroplasty (THA), despite a lack of randomized trials to evaluate its efficacy for this indication. The objective of this study was to assess the analgesic benefit of FIB after THA. Our primary hypothesis was administration of FIB decreases the intensity of postoperative pain (numeric rating scale [NRS-11] score) compared with sham block (SB) in patients after THA. Methods After institutional review board approval and informed consent, 32 eligible patients having THA were recruited. In the postoperative care unit, although all patients received intravenous morphine sulfate patient-controlled analgesia, patients reporting pain of 3 or greater on the NRS-11 scale were randomized to receive ultrasound-guided fascia iliaca (30 mL 0.5% ropivacaine) or SB (30 mL 0.9% NaCl) using identical technique, below fascia iliaca. The primary outcome was pain intensity (NRS-11) after FIB. Results Thirty-two patients (16 in each group) completed the study; all patients received an FIB. There was no difference in pain intensity (NRS-11 = 5.0 ± 0.6 vs 4.7 ± 0.6, respectively) after FIB versus SB or in opioid consumption (8.97 ± 1.6 vs 5.7 ± 1.6 mg morphine, respectively) between the groups at 1 hour. The morphine consumption after 24 hours was similar in both groups (49.0 ± 29.9 vs 50.4 ± 34.5 mg, P = 0.88, respectively). Conclusions The evidence in these data suggests that the difference in average pain intensity after FIB versus SB was not significant (95% confidence interval, −2.2–1.4 NRS units).

Local and nerve block techniques for analgesia after shoulder surgery.

Fredrickson et al. [1] are to be commended for their summary, in this issue, of the value of various intra-articular and nerve block injections and infusion strategies for postoperative analgesia after shoulder surgery. Their review, presents an insightful synthesis of the published information and collective clinical experience suggesting that interscalene brachial plexus block (ISB) is superior to intra-articular or subacromial infiltration of local anaesthetic. The purpose of this editorial is to add balance to the authors’ opinions, generate additional debate and stimulate new research. In their review, Dr Fredrickson and colleagues make a compelling, if anecdotal, case that continuous interscalene block (CISB) may be indicated for most shoulder procedures. However, they were unable to conduct a meta-analysis of the data they identified in the literature, because few studies met their (quality) criteria for inclusion, indicating that there is a paucity of quality data on this subject. Regardless, the literature summarised by Fredrickson et al. [2] suggests that CISB results in reduced pain scores and tramadol consumption compared with single-shot interscalene block (SSISB) with 0.5% ropivacaine during the first 24 h postoperatively, even for relatively minor arthroscopic shoulder procedures such as acromioplasty, lateral clavicle excision and repair of labral tears. However, pain scores were similar on the second postoperative day, raising the question of whether or not such a difference would persist if a longer acting local anaesthetic (e.g. 0.5% bupivacaine) were used for SSISB. Similarly, Ilfeld et al. [3] presented data from their case–control study of patients undergoing total shoulder arthroplasty that demonstrated that patients receiving CISB achieved a significantly greater range of motion on the first postoperative day than those who do not; however, these benefits were not observed on the second postoperative day. Conversely, a randomised, controlled comparison of CISB with SSISB for open rotator cuff repair conducted by Klein et al. [4] revealed only modest reductions in visual analogue pain scores in the CISB group: respectively 10 vs 34 at 12 h, and 15 vs 28 at 24 h (out of a maximum score of 100). However, Klein et al.’s study was conducted over a decade ago and it can be argued that the techniques of the time may be inferior to the current standards of practice. Interscalene brachial plexus block is a standard of care in many institutions with regional anaesthesia traditions, such as that of Fredrickson and colleagues. It is no surprise then that they unambiguously opine that ISB is the preferred method following most shoulder procedures and suggest that whenever possible, CISB should be used. However, the authors themselves suggest that CISB techniques are more technically challenging than SSISB. In addition to adding to the burden of postoperative care for the patient and ⁄ or the caregiver, catheters can easily dislodge from their ideal placement, they may leak at the site of the insertion, infusion lines can get disconnected and the cost of the equipment is significantly greater than that of SSISB. In addition, potential side-effects of ISB such as Horner’s syndrome, hoarseness or phrenic nerve block (diaphragmatic paralysis) are typically limited to < 24 h with a single-injection technique. These side-effects may become more serious or distressing for patients when prolonged in the setting of CISB [5]. As an example, a recent survey of 172 patients who had received CISB revealed that nearly 10% complained of dyspnoea [6]. Readmission for chest pain and lower lobe collapse has also been reported with ambulatory interscalene catheters [7]. Serious complications related to interscalene catheters are uncommon, but the reported incidence of paraesthesia and dysaesthesia following CISB is not insignificant (8–19%) [6, 8, 9]. Infectious complications related to CISB, such as cellulitis and mediastinitis requiring surgical debridement, have also been reported [10]. Fredrickson and colleagues justifiably warn that ISB is an invasive procedure and should be performed only by practitioners with appropriate experience. However, no information is available on what constitutes the appropriate credentials commensurate with efficacy and safety, or how practitioners can acquire such experience. Some may argue that the introduction of ultrasound guidance for needle and catheter placement will help with the precision and consistency. However, a recent study of novice behavior during ultrasound-guided peripheral nerve blocks suggests that the number of procedures performed in order for the error curve to flatten out was approximately 70 even in an expert-supervised environment [11]. Can an occasional ISB user match the ‘gold standards’ of safety and efficacy of CISB reported by their super-specialised opinion leaders? On a patient level, CISB actually may not always provide adequate analgesia. Klein et al. [12] reported that despite continuous postoperative infusion of either interscalene or intra-articular ropivacaine following open rotator cuff repair, up to 70% of patients report severe pain. Moreover, achieving the right balance between shoulder analgesia (sensory blockade of the superior trunk) and an absence of motor block and ⁄ or paraesthesia in the rest of the limb can be challenging with CISB. Attempts at manipulating the volume and concentration of the delivered drug to establish better sensory-motor differentiation and more specific localisation of sensory blockade may produce inconsistent results [13]. Anaesthesia, 2010, 65, pages 547–555 .....................................................................................................................................................................................................................

The Sequence of Administration of 1.5% Mepivacaine and 0.5% Bupivacaine Does Not Affect Latency of Block Onset or Duration of Analgesia in Ultrasound-guided Interscalene Block

BACKGROUND:During peripheral nerve blockade, different local anesthetics may be sequentially administered. Typically, a short- or intermediate-acting local anesthetic is administered before a long-acting local anesthetic to achieve a block with rapid onset and long duration. However, there is a paucity of data on advantages of such sequencing. We hypothesized that when using a sequential mixture of mepivacaine and bupivacaine for ultrasound-guided interscalene block, the order of injection of the drugs does not influence the clinical characteristics of the block achieved. METHODS:Sixty-four patients undergoing arthroscopic shoulder surgery (aged 18–65 years; ASA physical status I–II) with a single-injection ultrasound-guided interscalene brachial plexus block as sole anesthetic were studied. The subjects were randomized to receive 1 of 2 local anesthetic sequences: 15 mL of mepivacaine 1.5% followed by 15 mL of bupivacaine 0.5% (group A), or the same local anesthetics in the reverse order (group B). The durations of sensory and motor block were the primary outcomes. Block onset was also assessed. RESULTS:Duration of motor block was similar between group A and group B (10.1 ± 4.7 hours vs 10.3 ± 5.1 hours, mean difference 0.2 hours, 95% confidence interval [CI] −3.3 to 2.9, P = 0.9). Duration of analgesia was also similar between group A and group B (9.5 ± 5.6 hours vs 10.2 ± 4.5 hours, mean difference 0.7 hours, 95% CI −3.2 to 1.9, P = 0.42). Onset of sensory block was similar between the 2 groups (15.9 ± 7.1 minutes for group A, 13.9 ± 7.0 minutes for group B, mean difference 1.9 minutes, 95% CI −1.4 to 5.2, P = 0.25). CONCLUSIONS:The sequence in which 15 mL mepivacaine 1.5% and 15 mL bupivacaine 0.5% are administered does not seem to have a clinically meaningful effect on duration or onset of ultrasound-guided interscalene brachial plexus block.

Reply to Drs Wolf and Gray.

To the Editor: We thank Drs Wolf and Gray 1 for their interest in our recent article on high-definition ultrasound imaging of the paraneural sheath and fascial compartments surrounding the sciatic nerve at the popliteal fossa. They draw attention to the complex architecture of the paraneural sheath distal to the sciatic nerve bifurcation and express concerns about potential nerve injury from a subparaneural injection at the popliteal fossa. Drs Wolf and Gray’s report is timely and warrants discussion because the “subparaneural compartment” has been described as the “new destination” and is being targeted for local anesthetic injection during a popliteal sciatic nerve block (SNB). Preliminary data also suggest that this practice improves block dynamics and is, therefore, desirable. Nevertheless, we believe Drs Wolf and Gray’s concerns are valid because the paraneural sheath is very closely apposed to the sciatic nerve (Fig. 1A); ultrasound localization of the paraneural sheath, even with high-definition ultrasound, is difficult; subparaneural injection requires placement of the needle tip very close to the epineurium of the sciatic nerve; and the lateral sural cutaneous nerve (LSCN) may also lie in the “line of fire” of the block needle (Fig. 1C). Moreover, there is no convincing evidence demonstrating a safe and reliable method of performing a subparaneural injection at the popliteal fossa. We agree with Drs Wolf and Gray that the architecture of the paraneural sheath is more complex distal to the bifurcation of the sciatic nerve than previously described. We have also recently identified the 2 small nerves, which Drs Wolf and Gray refer to, at the popliteal fossa using high-definition ultrasound imaging (Figs. 1 and 2). These small nerves are best visualized distal to the bifurcation of the sciatic nerve and in a superficial plane posterior to the condyles of the femur (Figs. 1F and 2F). The LSCN is the lateral of the 2 small nerves and can occasionally be identified before the local anesthetic injection (Fig. 1B), but the “fourth nerve” is only delineated after the local anesthetic injection (Figs. 1F and 2F). The identity of the “fourth nerve” is not clear, but Drs Wolf and Gray suggest that it is a branch of the tibial nerve (possibly the medial sural cutaneous nerve) that contributes to the formation of the sural nerve. We beg to differ because we have often traced its origin to the common peroneal nerve (CPN), using ultrasound imaging, and seen it branching out from the LSCN (Fig. 2D,F). On the basis of its position (ie, medial to the LSCN [Fig. 2F]) and published data, we believe it represents the peroneal communication branch (PCB) of the CPN. The PCB is the nerve that joins the medial sural communicating nerve to form the sural nerve. Ours may be the first report to demonstrate the PCB using ultrasound imaging in vivo. The origin of the PCB from the CPN is variable and follows one of the 3 basic patterns: type A (74%), the

Reply to Dr Murgatroyd et al.

is inserted out-of-plane (OOP) lateral to the femoral nerve. Needle tip position is confirmed by local anesthetic spread under fascia iliaca. B, Longitudinal parasagittal view of the needle with its tip in position under fascia iliaca. Cephalad spread of local anesthetic between fascia iliaca and the iliopsoas muscle can be visualized in real time. Letters to the Editor Regional Anesthesia and Pain Medicine • Volume 38, Number 5, September-October 2013

Reply to Dr Vaughan et al.

To the Editor: We thank Vaughan et al for their interest in our article, and we appreciate the sharing of their departmental experience regarding various technical and pharmacologic aspects of the fascia iliaca block (FIB) in patients having total hip arthroplasty. We would like to reemphasize the need for testing the efficacy and safety of various techniques in randomized controlled trials. The technique of FIB in our study had been administered to patients having total hip arthroplasty for decades using “blind” or “double pop” technique with claimed benefits that had not been formally evaluated. Therefore, we put the traditional technique of FIB to a hard test using ultrasound guidance to document the intended anesthetic spread in the used technique and found a surprising lack of analgesic benefit. The modifications suggested by Vaughan et al may indeed provide better analgesia; however, in the absence of their formal evaluation in randomized controlled trials, they should be considered opinions, just as was the traditional FIB technique before our study. Importantly, the safety

Reply to Drs Rowley and Emamdee.

To the Editor: W e read with interest the work by Shariat et al. The attempt to increase our knowledge of analgesia for hip arthroplasty is commendable; however, we have noted some debatable statistics and questionable methodology, which may cast doubt on the conclusion and summary of this article. The study protocol describes visual analog scale scoring for pain assessment; however, the article refers solely to the numeric rating scale 11 (NRS-11) score. This could easily be a typographical error in the study protocol; if, however, it is not, then the substitution of NRS-11 (in the article) for visual analog scale (in the study protocol) is questionable. The interchangeability of these 2 scoring systems has been controversial in the past. Indeed, such interchangeability has been questioned specifically for postoperative orthopedic patients. The NRS-11 data in this article are presented as continuous (numerical) data, data that can be represented on a number line. Clearly, one patient’s NRS score of 8, say, is not twice as much pain as his NRS score of 4. Similarly, a patient’s perception of a score of 6, for example, is not the same as another patient’s score of 6. Is it therefore wise to consider NRS scores as a continuous variable? Finally, we noted that the authors wanted a “... mean NRS approximately 8–9 for the SB group” and pain intensity ranged up to 10 in each group (for up to 30 minutes postblock). Assuming a pain score of 10 is not an instantaneous event, to have a patient with a pain score of 10 up to 30 minutes after a hip arthroplasty seems a long timewithout giving supplemental analgesia (apart from the patient controlled analgesia morphine and fascia iliaca block), all in the name of a randomized control trial.