Eric Albrecht

The Analgesic Efficacy of Ultrasound-Guided Transversus Abdominis Plane Block in Adult Patients: A Meta-Analysis.

BACKGROUND:Previous meta-analyses of the transversus abdominis plane (TAP) block have examined a maximum of 12 articles, including fewer than 650 participants, and have not examined the effect of ultrasound-guided techniques specifically. Recently, many trials that use ultrasound approaches to TAP block have been published, which report conflicting analgesic results. This meta-analysis aims to evaluate the analgesic efficacy of ultrasound-guided TAP blocks exclusively for all types of abdominal surgeries in adult patients. METHODS:This meta-analysis was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines. The primary outcome was cumulative IV morphine consumption at 6 hours postoperatively, analyzed according to the type of surgery, the type of surgical anesthesia, the timing of injection, the block approach adopted, and the presence of postoperative multimodal analgesia. Secondary outcomes included IV morphine consumption at 24 hours postoperatively; pain scores at rest and on movement at 6 and 24 hours postoperatively; and postoperative nausea and vomiting, pruritus, and rates of complications. RESULTS:Thirty-one controlled trials including 1611 adult participants were identified. Independent of the type of surgery (abdominal laparotomy, abdominal laparoscopy, and cesarean delivery) but not independent of the type of surgical anesthesia (general anesthesia, spinal anesthesia with or without intrathecal long-acting opioid), ultrasound-guided TAP block reduced IV morphine consumption at 6 hours postoperatively by a mean difference of 6 mg (95% confidence interval [CI], −7 to −4 mg; I2 = 94%; P < 0.00001). The magnitude of the reduction in morphine consumption at 6 hours postoperatively was not influenced by the timing of injection (I2 = 0%; P = 0.72), the block approach adopted (I2 = 0%; P = 0.72), or the presence of postoperative multimodal analgesia (I2 = 73%; P = 0.05). This difference persisted at 24 hours postoperatively (mean difference, −11 mg; 95% CI, −14 to −8 mg; I2 = 99%; P < 0.00001). Pain scores at rest and on movement were reduced at 6 hours postoperatively (mean difference at rest, −10; 95% CI, −15 to −5; I2 = 92%; P = 0.0002; mean difference on movement, −9; 95% CI, −14 to −5; I2 = 58%; P < 0.00001). There were neither differences in the incidence of postoperative nausea and vomiting (I2 = 1%; P = 0.59) nor in the pruritus (I2 = 12%; P = 0.58) Two minor complications (1 bruise and 1 anaphylactoid reaction) were reported in 1028 patients. CONCLUSIONS:Ultrasound-guided TAP block provides marginal postoperative analgesic efficacy after abdominal laparotomy or laparoscopy and cesarean delivery. However, it does not provide additional analgesic effect in patients who also received spinal anesthesia containing a long-acting opioid. The minimal analgesic efficacy is independent of the timing of injection, the approach adopted, or the presence of postoperative multimodal analgesia. Because of heterogeneity of the results, these findings should be interpreted with caution.

Validity of an Arterial Pressure Waveform Analysis Device: Does the Puncture Site Play a Role in the Agreement With Intermittent Pulmonary Artery Catheter Thermodilution Measurements?

OBJECTIVE The measurement of cardiac output is a key element in the assessment of cardiac function. Recently, a pulse contour analysis-based device without need for calibration became available (FloTrac/Vigileo, Edwards Lifescience, Irvine, CA). This study was conducted to determine if there is an impact of the arterial catheter site and to investigate the accuracy of this system when compared with the pulmonary artery catheter using the bolus thermodilution technique (PAC). DESIGN Prospective study. SETTING The operating room of 1 university hospital. PARTICIPANTS Twenty patients undergoing cardiac surgery. INTERVENTIONS CO was determined in parallel by the use of the Flotrac/Vigileo systems in the radial and femoral position (CO_rad and CO_fem) and by PAC as the reference method. Data triplets were recorded at defined time points. The primary endpoint was the comparison of CO_rad and CO_fem, and the secondary endpoint was the comparison with the PAC. MEASUREMENTS AND MAIN RESULTS Seventy-eight simultaneous data recordings were obtained. The Bland-Altman analysis for CO_fem and CO_rad showed a bias of 0.46 L/min, precision was 0.85 L/min, and the percentage error was 34%. The Bland-Altman analysis for CO_rad and PAC showed a bias of -0.35 L/min, the precision was 1.88 L/min, and the percentage error was 76%. The Bland-Altman analysis for CO_fem and PAC showed a bias of 0.11 L/min, the precision was 1.8 L/min, and the percentage error was 69%. CONCLUSION The FloTrac/Vigileo system was shown to not produce exactly the same CO data when used in radial and femoral arteries, even though the percentage error was close to the clinically acceptable range. Thus, the impact of the introduction site of the arterial catheter is not negligible. The agreement with thermodilution was low.

The maximum effective needle-to-nerve distance for ultrasound-guided interscalene block: an exploratory study.

One of the most fundamental, 1 yet controversial, tenets of regional anesthesia practice has been the adage “no paresthesia, no anesthesia.” Implicit to this concept is the requirement for direct needle-nerve contact to achieve a successful block. The advent of ultrasound (US) guidance for peripheral nerve blockade (PNB) has enabled providers to position the needle tip purposefully as close as possible to, and even inside, the target nerve. Consequently, much of the contemporary regional anesthesia literature has focused on the question “How close is too close?” while investigators challenge the safety limits of US-guided PNB. Regrettably, the risk of nerve injury persists despite US guidance and is underscored by reports of new functional deficits after interscalene brachial plexus block (ISB) performed under US guidance by experienced providers. Given that mechanical needle-nerve trauma is an important mechanism of peripheral nerve injury, providers are cautioned to avoid intentional intraneural injection or needle-nerve contact during US-guided PNB.8,14,15 Potentially hazardous needleto-nerve proximity may be especially relevant during US-guided ISB, where inadvertent injection beneath the epineurium may be as high as 50%. Subepineural, and particularly intrafascicular, injection of local anesthetic may increase the risk of nerve injury.17 Neural elements of the interscalene brachial plexus are predominantly comprised of axonal tissue and may be especially

Single-injection or Continuous Femoral Nerve Block for Total Knee Arthroplasty?

BackgroundThe ideal local anesthetic regime for femoral nerve block that balances analgesia with mobility after total knee arthroplasty (TKA) remains undefined.Questions/purposesWe compared two volumes and concentrations of a fixed dose of ropivacaine for continuous femoral nerve block after TKA to a single injection femoral nerve block with ropivacaine to determine (1) time to discharge readiness; (2) early pain scores and analgesic consumption; and (3) functional outcomes, including range of motion and WOMAC scores at the time of recovery.MethodsNinety-nine patients were allocated to one of three continuous femoral nerve block groups for this randomized, placebo-controlled, double-blind trial: a high concentration group (ropivacaine 0.2% infusion), a low concentration group (ropivacaine 0.1% infusion), or a placebo infusion group (saline 0.9% infusion). Infusions were discontinued on postoperative Day (POD) 2. The primary outcome was time to discharge readiness. Secondary outcomes included opioid consumption, pain, and functional outcomes. Ninety-three patients completed the study protocol; the study was halted early because of unanticipated changes to pain protocols at the host institution, by which time only 61% of the required number of patients had been enrolled.ResultsWith the numbers available, the mean time to discharge readiness was not different between groups (high concentration group, 62 hours [95% confidence interval [CI], 51–72 hours]; low concentration group, 73 hours [95% CI, 63–83 hours]; placebo infusion group 65 hours [95% CI, 56–75 hours]; p = 0.27). Patients in the low concentration group consumed significantly less morphine during the period of infusion (POD 1, high concentration group, 56 mg [95% CI, 42–70 mg]; low concentration group, 35 mg [95% CI, 27–43 mg]; placebo infusion group, 48 mg [95% CI, 38–59 mg], p = 0.02; POD 2, high concentration group, 50 mg [95% CI, 41–60 mg]; low concentration group, 33 mg [95% CI, 24–42 mg]; placebo infusion group, 39 mg [95% CI, 30–48 mg], p = 0.04); however, there were no important differences in pain scores or opioid-related side effects with the numbers available. Likewise, there were no important differences in functional outcomes between groups.ConclusionsBased on this study, which was terminated prematurely before the desired sample size could be achieved, we were unable to demonstrate that varying the concentration and volume of a fixed-dose ropivacaine infusion for continuous femoral nerve block influences time to discharge readiness when compared with a conventional single-injection femoral nerve block after TKA. A low concentration of ropivacaine infusion can reduce postoperative opioid consumption but without any important differences in pain scores, side effects, or functional outcomes. These pilot data may be used to inform the statistical power of future randomized trials.Level of EvidenceLevel II, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Optimal Dose of Perineural Dexamethasone to Prolong Analgesia After Brachial Plexus Blockade: A Systematic Review and Meta-analysis

BACKGROUND: Perineural dexamethasone has gained popularity in regional anesthesia to prolong analgesia duration. However, uncertainty remains regarding the optimal perineural dose. Clarification of this characteristic is of significant importance as the administration of dexamethasone may lead to dose-dependent complications. The objective of this meta-analysis was to define the optimal perineural dexamethasone dose to prolong analgesia after brachial plexus blockade for adult patients undergoing upper limb surgery. METHODS: We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement guidelines and searched databases including MEDLINE, PubMed, and EMBASE until January 2017, without language restriction. Only trials comparing perineural dexamethasone and local anesthetics with local anesthetics alone for brachial plexus blocks were included in the present meta-analysis. The Cochrane Collaboration’s Risk of Bias Tool was used to assess the methodological quality of each trial and meta-analyses were performed following a random effects model. The primary outcome was duration of analgesia for each type of local anesthetic (short-/intermediate-acting and long-acting local anesthetics). A meta-regression followed by a subgroup analysis were performed to assess the impact of different perineural dexamethasone doses on duration of analgesia; for the latter analysis, trials were grouped in low (1–4 mg) and moderate (5–10 mg) dexamethasone doses. Secondary outcomes included the rate of neurologic complication and resting pain scores and morphine consumption within the first 24 hours. RESULTS: Thirty-three controlled trials, including 2138 patients, were identified. The meta-regression revealed a ceiling effect with a perineural dexamethasone dose of 4 mg when combined with short-/intermediate-acting (8 trials; 366 participants) or long-acting local anesthetics (23 trials; 1869 participants). This finding was confirmed by subgroup analyses comparing low and moderate dexamethasone doses. With short-/intermediate-acting local anesthetics, the mean difference (95% confidence interval) of analgesia duration with low and moderate doses was 277 (234–322) minutes and 229 (161–297) minutes, respectively. With long-acting local anesthetics, the mean differences with low and moderate doses were 505 (342–669) minutes and 509 (443–575) minutes. Perineural dexamethasone did not increase the rate of neurologic complications (risk ratio [95% confidence interval], 1.40 [0.54–3.63]). The Grades of Recommendation, Assessment, Development, and Evaluation quality of evidence for the primary and secondary outcomes were very low, due mainly to limitations, inconsistency, indirectness, and publication bias. CONCLUSIONS: There is currently very low quality evidence that 4 mg of perineural dexamethasone represents a ceiling dose that prolongs analgesia duration by a mean period of 6 and 8 hours when combined with short-/intermediate- or long-acting local anesthetics, respectively. Additional data are needed to explore the threshold for this effect, particularly with doses below 4 mg. The risk of neurologic complications is probably not increased (very low evidence).

Semantics, misnomer, or uncertainty: where is the epineurium on ultrasound?

To the Editor: Iwould like to thank Dr. Fredrickson for his kind introductory remarks and his comments on my Labat lecture article. Dr. Fredrickson makes the point that ambulatory perineural techniques are highly effective in orthopedic surgery, and he dismisses wound infiltration and catheter wound infusions (CWIs) as an ‘‘unsubstantiated (but probably ineffective) alternative.’’ My article included several references to goodquality studies and meta-analyses showing that both perineural and CWI techniques are effective, but head-to-head comparative studies are lacking. My article was about the entire topic of ambulatory catheter techniques not just rotator cuff surgery. Dr. Fredrickson’s statement about wound infiltration and CWI techniques ignores the large body of evidence-based literature on the topic, includingmeta-analysis and well-controlled studies showing CWI to be highly effective after open colectomy, cesarean delivery, knee arthroplasty, and total hip arthroplasy. Two new studies show that CWI is very effective after minimally invasive total hip arthroplasty and superior to intrathecal morphine after cesarean delivery. The evidence-based, procedure-specific postoperative pain management group (PROSPECT) currently recommends wound infiltration for inguinal herniotomy, laparoscopic cholecystectomy, hemorrhoidectomy, hysterectomy, and open colon surgery (www.postoppain.org). Similar recommendations are in the Expert Panel guidelines of the French Society of Anesthesia and Intensive Care (SFAR). Catheter wound infusion was recommended with level 1 evidence in the second (2005) and third (2010) editions of The Australian and New Zealand College of Anaesthetists and Faculty of Pain Medicine. Nevertheless, I concede that CWI will not be effective in all surgical procedures. This needs to be evaluated in future studies. Dr. Fredrickson emphasized the efficacy of perineural techniques but said nothing about the possible problems. In general, such techniques are quite safe; however, there are several potential risks. This was noted in a recent review of ambulatory perineural techniques by Dr. Ilfeld, a leading authority in the field. Potential risks include catheter dislodgement (up to 30%), secondary block failure due to inaccurate catheter placement (up to 40%), patient falls with femoral blocks (up to 7%), and pulmonary complications with plexus block (case report of lower lobe collapse at home after interscalene block and of pleural effusion). For interscalene block, other risk factors are hoarseness, Horner syndrome, diaphragmatic paralysis, pneumothorax, and paresthesia. Dr. Fredrickson notes that in Auckland, nearly 100% of private patients receive interscalene infusions at home after rotator cuff surgery. Although that is impressive, it would have been helpful to know the block success rates, requirements of rescue analgesics, and some data about postoperative rehabilitation. In summary, the efficacy of ambulatory perineural techniques is not in doubt; it is their implementation in routine practice. Despite robust efficacy evidence, perineural techniques are still not a routine method of pain management in most hospitalized patients. Regrettably, a similar fate awaits ambulatory perineural techniques, unless or until orthopedic subspecialization improves. The reasons were outlined in my paper. The Hippocratic ‘‘Primum non nocere’’ (first do no harm) applies to everything we do, but nowhere more so than for the medically unsupervised patient at home. Catheter wound infusion at home is simple, safe, and effective for many, but perhaps not all, procedures. Only head-tohead comparative studies will show which of the 2 catheter techniques is most costeffective for a given surgical procedure. Until then, nothing in Dr. Fredrickson’s letter has convinced me to changemy views, which are aptly condensed in the title of my paper, ‘‘Perineural catheter analgesia as a routine method after ambulatory surgeryVeffective but unrealistic.’’ The word ‘‘routine’’ is crucial for our debate. On a personal level, I am very encouraged that anesthesiologists like Dr. Fredrickson and others in ‘‘specialized centers’’ are ‘‘fine-tuning’’ and improving ambulatory perineural infusions for postoperative painVa highly effective technique I had the privilege of introducing 15 years ago.

Reply to Drs Bhatt and Hofmann.

Coment on : The maximum effective needle-to-nerve distance for ultrasound-guided interscalene block: an exploratory study. [Reg Anesth Pain Med. 2014]

Peri-operative intravenous administration of magnesium sulphate and postoperative pain

Intravenous magnesium has been reported to improve postoperative pain; however, the evidence is inconsistent. The objective of this quantitative systematic review is to evaluate whether or not the peri‐operative administration of intravenous magnesium can reduce postoperative pain. Twenty‐five trials comparing magnesium with placebo were identified. Independent of the mode of administration (bolus or continuous infusion), peri‐operative magnesium reduced cumulative intravenous morphine consumption by 24.4% (mean difference: 7.6 mg, 95% CI −9.5 to −5.8 mg; p < 0.00001) at 24 h postoperatively. Numeric pain scores at rest and on movement at 24 h postoperatively were reduced by 4.2 (95% CI −6.3 to −2.1; p < 0.0001) and 9.2 (95% CI −16.1 to −2.3; p = 0.009) out of 100, respectively. We conclude that peri‐operative intravenous magnesium reduces opioid consumption, and to a lesser extent, pain scores, in the first 24 h postoperatively, without any reported serious adverse effects.

The analgesic efficacy and safety of neuraxial magnesium sulphate

Eighteen published trials have examined the use of neuraxial magnesium as a peri‐operative adjunctive analgesic since 2002, with encouraging results. However, concurrent animal studies have reported clinical and histological evidence of neurological complications with similar weight‐adjusted doses. The objectives of this quantitative systematic review were to assess both the analgesic efficacy and the safety of neuraxial magnesium. Eighteen trials comparing magnesium with placebo were identified. The time to first analgesic request increased by 11.1% after intrathecal magnesium administration (mean difference: 39.6 min; 95% CI 16.3–63.0 min; p = 0.0009), and by 72.2% after epidural administration (mean difference: 109.5 min; 95% CI 19.6–199.3 min; p = 0.02) with doses of between 50 and 100 mg. Four trials monitored for neurological complications: of the 140 patients included, only a 4‐day persistent headache was recorded. Despite promising peri‐operative analgesic effect, the risk of neurological complications resulting from neuraxial magnesium has not yet been adequately defined.