Immediate Effects of a Continuous Peripheral Nerve Block on Postamputation Phantom and Residual Limb Pain: Secondary Outcomes From a Multicenter Randomized Controlled Clinical Trial.

BACKGROUND: We recently reported that a 6-day continuous peripheral nerve block reduced established postamputation phantom pain 3 weeks after treatment ended. However, the immediate effects of perineural infusion (secondary outcomes) have yet to be reported. METHODS: Participants from 5 enrolling academic centers with an upper or lower limb amputation and established phantom pain received a single-injection ropivacaine peripheral nerve block(s) and perineural catheter insertion(s). They were subsequently randomized to receive a 6-day ambulatory perineural infusion of either ropivacaine 0.5% or normal saline in a double-masked fashion. Participants were contacted by telephone 1, 7, 14, 21, and 28 days after the infusion started, with pain measured using the Numeric Rating Scale. Treatment effects were assessed using the Wilcoxon rank-sum test at each time point. Adjusting for 4 time points (days 1, 7, 14, and 21), P < .0125 was deemed statistically significant. Significance at 28 days was reported using methods from the original, previously published article. RESULTS: Pretreatment average phantom and residual pain scores were balanced between the groups. The day after infusion initiation (day 1), average phantom, and residual limb pain intensity was lower in patients receiving local anesthetic (n = 71) versus placebo (n = 73): median [quartiles] of 0 [0-2.5] vs 3.3 [0-5.0], median difference (98.75% confidence interval [CI]) of -1.0 (-3.0 to 0) for phantom pain (P = .001) and 0 [0-0] vs 0 [0-4.3], and median difference 0.0 (-2.0 to 0.0) for residual limb pain (P < .001). Pain's interference with physical and emotional functioning as measured with the interference domain of the Brief Pain Inventory improved during the infusion on day 1 for patients receiving local anesthetic versus placebo: 0 [0-10] vs 10 [0-40], median difference (98.75% CI) of 0.0 (-16.0 to 0.0), P = .002. Following infusion discontinuation (day 6), a few differences were found between the active and placebo treatment groups between days 7 and 21. In general, sample medians for average phantom and residual limb pain scores gradually increased after catheter removal for both treatments, but to a greater degree in the control group until day 28, at which time the differences between the groups returned to statistical significance. CONCLUSIONS: This secondary analysis suggests that a continuous peripheral nerve block decreases phantom and residual limb pain during the infusion, although few improvements were again detected until day 28, 3 weeks following catheter removal.

Continuous Popliteal-Sciatic Blocks for Postoperative Analgesia: Traditional Proximal Catheter Insertion Superficial to the Paraneural Sheath Versus a New Distal Insertion Site Deep to the Paraneural Sheath.

We tested the hypothesis that during a continuous popliteal-sciatic nerve block, postoperative analgesia is improved with the catheter insertion point "deep" to the paraneural sheath immediately distal to the bifurcation between the tibial and common peroneal branches, compared with the traditional approach "superficial" to the paraneural sheath proximal to the bifurcation. The needle tip location was determined to be accurately located with a fluid bolus visualized with ultrasound; however, catheters were subsequently inserted without a similar fluid injection and visualization protocol (visualized air injection was permitted and usually implemented, but not required per protocol). The average pain (0-10 scale) the morning after surgery for subjects with a catheter inserted at the proximal subparaneural location (n = 31) was a median (interquartile) of 1.5 (0.0-3.5) vs 1.5 (0.0-4.0) for subjects with a catheter inserted at the distal supraparaneural location (n = 32; P = .927). Secondary outcomes were similarly negative.

Post-mastectomy cancer recurrence with and without a continuous paravertebral block in the immediate postoperative period: a prospective multi-year follow-up pilot study of a randomized, triple-masked, placebo-controlled investigation.

PURPOSE: Retrospective studies have associated perioperative regional anesthesia/analgesia during mastectomy for breast cancer with a decreased incidence of cancer recurrence. However, to date, no prospective data from a randomized controlled trial have been reported. In a previous study we found that extending a single-injection paravertebral block with a multiple-day perineural local anesthetic infusion improves analgesia. This follow-up study investigates the rates of cancer recurrence for the single-injection and multiple-day infusion treatments. METHODS: Patients undergoing unilateral (n = 24) or bilateral mastectomy (n = 36) were included in the study. All patients had been diagnosed with breast cancer or tumor in situ, except for six patients who were receiving prophylactic bilateral mastectomy and were excluded from analyses. Patients received unilateral or bilateral single-injection thoracic paravertebral block(s) corresponding to their surgical site(s) with ropivacaine and perineural catheter(s). Subsequently, patients were randomized to receive either ropivacaine 0.4% (n = 30) or normal saline (n = 30) via their catheter(s) until catheter removal on postoperative day 3. Cancer recurrence from the date of surgery until at least 2 years post surgery was investigated via chart review. RESULTS: Five of the 54 (9.2%) patients experienced a cancer recurrence following mastectomy-3 of 26 (11.5%) of the patients with perineural ropivacaine and 2 of 28 (7.1%) of the patients with perineural saline. CONCLUSIONS: This pilot study found no evidence that extending a single-injection paravertebral block with a multi-day perineural local anesthetic infusion decreases the risk of post-mastectomy cancer recurrence. However, due to the small sample size of this investigation, further research is needed to draw definitive conclusions.

Continuous Popliteal Sciatic Blocks: Does Varying Perineural Catheter Location Relative to the Sciatic Bifurcation Influence Block Effects? A Dual-Center, Randomized, Subject-Masked, Controlled Clinical Trial.

BACKGROUND: Multiple studies have demonstrated that, for single-injection popliteal sciatic nerve blocks, block characteristics are dependent upon local anesthetic injection relative to the sciatic nerve bifurcation. In contrast, this relation remains unexamined for continuous popliteal sciatic nerve blocks. We, therefore, tested the hypothesis that postoperative analgesia is improved with the perineural catheter tip at the level of the bifurcation compared with 5 cm proximal to the bifurcation. METHODS: Preoperatively, subjects having moderately painful foot or ankle surgery were randomly assigned to receive an ultrasound-guided subepimyseal perineural catheter inserted either at or 5 cm proximal to the sciatic nerve bifurcation. Subjects received a single injection of mepivacaine 1.5% either via the insertion needle preoperatively or the perineural catheter postoperatively, followed by an infusion of ropivacaine 0.2% (6 mL/h basal, 4 mL bolus, and 30-min lockout) for the study duration. The primary end point was the average pain measured on a numeric rating scale (0-10) in the 3 hours before a data collection telephone call the morning after surgery. RESULTS: The average numeric rating scale of subjects with a catheter inserted at the sciatic nerve bifurcation (n = 64) was a median (10th, 25th to 75th, and 90th quartiles) of 3.0 (0.0, 2.4-5.0, and 7.0) vs 2.0 (0.0, 1.0-4.0, and 5.0) for subjects with a catheter inserted proximal to the bifurcation (n = 64; P = 0.008). Similarly, maximum pain scores were greater in the group at the bifurcation: 6.0 (3.0, 4.4-8.0, and 9.0) vs 5.0 (0.0, 3.0-8.0, and 10.0) (P = 0.019). Differences between the groups for catheter insertion time, opioid rescue dose, degree of numbness in the foot/toes, catheter dislodgement, and fluid leakage did not reach statistical significance. CONCLUSIONS: For continuous popliteal sciatic nerve blocks, a catheter inserted 5 cm proximal to the sciatic nerve bifurcation provides superior postoperative analgesia in subjects having moderately painful foot or ankle surgery compared with catheters located at the bifurcation. This is in marked contrast with single-injection popliteal sciatic nerve blocks for which benefits are afforded to local anesthetic injection distal, rather than proximal, to the bifurcation.

Nutrient-dense, Plant-rich Dietary Intervention Effective at Reducing Cardiovascular Disease Risk Factors for Worksites: A Pilot Study.

UNLABELLED: conduct interventions for health promotion and disease prevention to ameliorate chronic risk factors for disease, such as for cardiovascular disease (CVD). Likewise, nutrient-dense, plant-rich (NDPR) dietary patterns have been shown to be effective at preventing and improving chronic-disease conditions, including CVD. Objective • The study's aim was to determine the feasibility and effectiveness of an NDPR dietary intervention for worksites to lower CVD risk factors. Design • The study was a 6-wk pilot intervention using a pretest and posttest design. SETTING: The intervention was conducted at the Northern Arizona University (Flagstaff, AZ, USA) and sponsored by its Employee Assistance and Wellness Department. Participants • Participants were 35 employees with body mass indexes (BMIs) >25 kg/m2 who were ready and willing to make a lifestyle change, who were not currently participating in a weight loss program, and who were not taking any medications that could increase medical risk or had weight loss as a primary side effect. The average age of participants was 42.57 y; 91.4% were female, and 80% were Caucasian. Intervention • The intervention used a dietary protocol consisting of the daily consumption of greens, beans, legumes, and a variety of other vegetables, as well as fresh or frozen whole fruits, nuts, seeds, and whole grains. Participants were encouraged to minimize the consumption of refined grains, vegetable oils, processed foods, and animal products. Outcome Measures • The study measured serum lipids, height, weight, waist and hip circumference, waist-to-hip ratio, and blood pressure. Results • Based on paired-sample t tests and Wilcoxon signed-ranks test with a maximum level of P = .05, the intervention resulted in significant changes in weight, BMI, waist and hip measurements, high-density lipoproteins, low-density lipoproteins, and estimated average glucose. Conclusions • The findings favorably revealed that an NDPR dietary intervention that was developed for worksites was an effective approach for reducing CVD risk factors.

Fall Risk Associated with Continuous Peripheral Nerve Blocks Following Knee and Hip Arthroplasty.

Combined scientific advances in pharmaceutical agents, perineural blocks, and pump delivery capabilities such as those used with continuous peripheral nerve blocks have demonstrated advantages in pain management for patients undergoing joint arthroplasty. This report documents the incidence of falls increased after the implementation of a continuous peripheral nerve block program for patients undergoing knee and hip arthroplasty in an academic medical center.

Persistent postmastectomy pain and pain-related physical and emotional functioning with and without a continuous paravertebral nerve block: a prospective 1-year follow-up assessment of a randomized, triple-masked, placebo-controlled study.

BACKGROUND: In a previous randomized, triple-masked, placebo-controlled study, the authors demonstrated that extending a single-injection paravertebral nerve block with a multiple-day perineural local anesthetic infusion improves analgesia and decreases pain-related dysfunction during the 3-day infusion but not subsequent to catheter removal within 1 month after mastectomy. This report describes a prospective follow-up study of the previously published trial to investigate the possibility that extending a single-injection paravertebral block with a multiple-day infusion may decrease persistent postsurgical pain as well as pain-induced emotional and functional dysfunction 1 year after mastectomy. METHODS: Subjects undergoing uni- or bilateral mastectomy received unilateral (n = 24) or bilateral (n = 36) single-injection thoracic paravertebral block(s) with ropivacaine and perineural catheter(s). The subjects were randomized to receive either ropivacaine 0.4 % (n = 30) or normal saline (n = 30) via their catheters until the catheters were removed on postoperative day 3. Chronic pain and pain-related physical and emotional dysfunction were measured using the Brief Pain Inventory (BPI). RESULTS: No statistically significant difference between treatments 3 months after surgery was observed with the BPI. In contrast, after 12 months, only 4 subjects (13 %) who had received a perineural ropivacaine infusion reported pain-induced dysfunction compared with 14 (47 %) who had received saline infusion (P = 0.011). At 12 months, the mean BPI was 1.6 ± 4.6 for the subjects who received ropivacaine versus 5.9 ± 11.3 for the subjects who received saline (P = 0.007). CONCLUSIONS: Adding a multiple-day, continuous ropivacaine infusion to a single-injection ropivacaine paravertebral nerve block may result in a lower incidence of pain as well as pain-related physical and emotional dysfunction 1 year after mastectomy.

Discharge Readiness after Tricompartment Knee Arthroplasty: Adductor Canal versus Femoral Continuous Nerve Blocks-A Dual-center, Randomized Trial.

BACKGROUND: The authors conducted a randomized, controlled, parallel-arm, superiority study to test the hypothesis that a continuous adductor canal block decreases the time to attain four discharge criteria compared with a continuous femoral nerve block after tricompartment knee arthroplasty. METHODS: Subjects undergoing tricompartment knee arthroplasty were randomized using computer-generated lists to either an adductor canal or femoral perineural catheter (3-day ropivacaine 0.2% infusion) in an unmasked manner. The primary outcome was the time to attain four criteria: (1) adequate analgesia; (2) intravenous opioids independence; (3) ability to stand, walk 3 m, return, and sit down; and (4) ambulate 30 m. RESULTS: Subjects with an adductor canal catheter (n = 39) reached all four criteria in a median of 55 h (interquartile, 42 to 63 h) compared with 61 h (49 to 69 h) for those with a femoral catheter (n = 41; 95% CI, -13 to 1 h; P = 0.12). The percentage of subjects who reached the two mobilization criteria on postoperative days 1 and 2 were 72 and 95% for those with an adductor canal catheter (n = 39), but only 27 and 76% in subjects with a femoral catheter (n = 41; both P < 0.001). Differences in pain scores at rest and intravenous opioid requirements were minimal, but femoral infusion improved dynamic analgesia (P = 0.01 to 0.02). CONCLUSION: Compared with a continuous femoral nerve block, a continuous adductor canal block did not appreciably decrease the time to overall discharge readiness even though it did decrease the time until adequate mobilization, primarily because both groups experienced similar analgesia and intravenous opioid requirements that--in most cases--exceeded the time to mobilization.

Continuous transversus abdominis plane (TAP) blocks for postoperative pain control after hernia surgery: a randomized, triple-masked, placebo-controlled study.

BACKGROUND: Single-injection transversus abdominis plane (TAP) block provides postoperative analgesia and decreases supplemental analgesic requirements. However, there is currently no evidence from randomized, controlled studies investigating the possible benefits of continuous TAP blocks. Therefore, the aim of this randomized, triple-masked, placebo-controlled study was to determine if benefits are afforded by adding a multiple-day, ambulatory, continuous ropivacaine TAP block to a single-injection block following hernia surgery. METHODS: Preoperatively, subjects undergoing unilateral inguinal (N=19) or peri-umbilical (N=1) hernia surgery received unilateral or bilateral TAP perineural catheter(s), respectively. All received a ropivacaine 0.5% (20 mL) bolus via the catheter(s). Subjects were randomized to either postoperative perineural ropivacaine 0.2% or normal saline using portable infusion pump(s). Subjects were discharged home where the catheter(s) were removed the evening of postoperative day (POD) 2. Subjects were contacted on POD 0-3. The primary endpoint was average pain with movement (scale: 0-10) queried on POD 1. RESULTS: Twenty subjects of a target 30 were enrolled due to the primary surgeon's unanticipated departure from the institution. Average pain queried on POD 1 for subjects receiving ropivacaine (N=10) was a mean (standard deviation) of 3.0 (2.6) vs 2.8 (2.7) for subjects receiving saline (N=10; 95% confidence interval difference in means -2.9 to 3.4; P=0.86). There were no statistically significant differences detected between treatment groups in any secondary endpoint. CONCLUSIONS: The results of this study do not support adding an ambulatory, continuous ropivacaine infusion to a single-injection ropivacaine TAP block for hernia surgery. However, the present investigation was underpowered, and further study is warranted.

Physiological and Family-Level Correlates of Autistic Adolescents' Sleep Quality.

PURPOSE: Autistic adolescents commonly experience sleep-related difficulties and prior studies have sought to separately examine physiological and family-level predictors of their sleep quality. The current study aimed to conceptually replicate and extend to an adolescent sample a prior study that found respiratory sinus arrhythmia was associated with sleep quality in autistic children. In addition, the current study also examined whether the quality of the family environment was associated with sleep quality in autistic adolescents. METHODS: The sample consisted of 107 autistic adolescents who completed a baseline measure of respiratory sinus arrhythmia and then watched a video of their parents engaged in a discussion about a topic of disagreement while their respiratory sinus arrhythmia reactivity was measured. Adolescents also completed questionnaires measuring their sleep quality and family environment. RESULTS: In regression models, adolescents' physiological functioning was not a significant predictor of their sleep quality; however, adolescents living in poorer quality family environments reported worse sleep quality after controlling for their physiological functioning. The interaction between physiological functioning and the family environment predicting sleep quality was non-significant. CONCLUSION: Although the current study did not conceptually replicate prior work, the findings highlight the importance of the family environment for adolescents' sleep. Implications and future directions are discussed.

A longitudinal examination of mental health and marital functioning of mothers and fathers of autistic adolescents during COVID-19.

LAY ABSTRACT: Parents of autistic children may be especially vulnerable to the negative effects of COVID-19. The current study examined changes in mental health and marital functioning of mothers and fathers of autistic children across three time points between April and October 2020. The study also explored whether pre-COVID factors could predict outcomes during the pandemic. Participants were 94 mothers and 58 fathers of autistic children drawn from a larger study about family relationships and autistic children's mental health that began prior to the pandemic. Results indicated that mothers reported higher levels of mental health problems compared to fathers in July and October 2020. Levels of mental health and marital functioning did not change between April and October 2020. Pre-pandemic child functioning and marital satisfaction predicted changes in mother's ratings of marital satisfaction. The findings have implications for ways to best support families during challenging periods.

Liposomal bupivacaine as a single-injection peripheral nerve block: a dose-response study.

BACKGROUND: Currently available local anesthetics approved for single-injection peripheral nerve blocks have a maximum duration of <24 hours. A liposomal bupivacaine formulation (EXPAREL, Pacira Pharmaceuticals, Inc., San Diego, CA), releasing bupivacaine over 96 hours, recently gained Food and Drug Administration approval exclusively for wound infiltration but not peripheral nerve blocks. METHODS: Bilateral single-injection femoral nerve blocks were administered in healthy volunteers (n = 14). For each block, liposomal bupivacaine (0-80 mg) was mixed with normal saline to produce 30 mL of study fluid. Each subject received 2 different doses, 1 on each side, applied randomly in a double-masked fashion. The end points included the maximum voluntary isometric contraction (MVIC) of the quadriceps femoris muscle and tolerance to cutaneous electrical current in the femoral nerve distribution. Measurements were performed from baseline until quadriceps MVIC returned to 80% of baseline bilaterally. RESULTS: There were statistically significant dose responses in MVIC (0.09%/mg, SE = 0.03, 95% confidence interval [CI], 0.04-0.14, P = 0.002) and tolerance to cutaneous current (-0.03 mA/mg, SE = 0.01, 95% CI, -0.04 to -0.02, P < 0.001), however, in the opposite direction than expected (the higher the dose, the lower the observed effect). This inverse relationship is biologically implausible and most likely due to the limited sample size and the subjective nature of the measurement instruments. While peak effects occurred within 24 hours after block administration in 75% of cases (95% CI, 43%-93%), block duration usually lasted much longer: for bupivacaine doses >40 mg, tolerance to cutaneous current did not return to within 20% above baseline until after 24 hours in 100% of subjects (95% CI, 56%-100%). MVIC did not consistently return to within 20% of baseline until after 24 hours in 90% of subjects (95% CI, 54%-100%). Motor block duration was not correlated with bupivacaine dose (0.06 hour/mg, SE = 0.14, 95% CI, -0.27 to 0.39, P = 0.707). CONCLUSIONS: The results of this investigation suggest that deposition of a liposomal bupivacaine formulation adjacent to the femoral nerve results in a partial sensory and motor block of >24 hours for the highest doses examined. However, the high variability of block magnitude among subjects and inverse relationship of dose and response magnitude attests to the need for a phase 3 study with a far larger sample size, and that these results should be viewed as suggestive, requiring confirmation in a future trial.

Treating intractable phantom limb pain with ambulatory continuous peripheral nerve blocks: a pilot study.

BACKGROUND: There is currently no reliable treatment for phantom limb pain (PLP). Chronic PLP and associated cortical abnormalities may be maintained from abnormal peripheral input, raising the possibility that a continuous peripheral nerve block (CPNB) of extended duration may permanently reorganize cortical pain mapping, thus providing lasting relief. METHODS: Three men with below-the-knee (2) or -elbow (1) amputations and intractable PLP received femoral/sciatic or infraclavicular perineural catheter(s), respectively. Subjects were randomized in a double-masked fashion to receive perineural ropivacaine (0.5%) or normal saline for over 6 days as outpatients using portable electronic infusion pumps. Four months later, subjects returned for repeated perineural catheter insertion and received an ambulatory infusion with the alternate solution ("crossover"). Subjects were followed for up to 1 year. RESULTS: By chance, all three subjects received saline during their initial infusion and reported little change in their PLP. One subject did not receive crossover treatment, but the remaining two subjects reported complete resolution of their PLP during and immediately following treatment with ropivacaine. One subject experienced no PLP recurrence through the 52-week follow-up period and the other reported mild PLP occurring once each week of just a small fraction of his original pain (pretreatment: continuous PLP rated 10/10; posttreatment: no PLP at baseline with average of one PLP episode each week rated 2/10) for 12 weeks (lost to follow-up thereafter). CONCLUSIONS: A prolonged ambulatory CPNB may be a reliable treatment for intractable PLP. The results of this pilot study suggest that a large, randomized clinical trial is warranted.

Patient-centered results from a multicenter study of continuous peripheral nerve blocks and postamputation phantom and residual limb pain: secondary outcomes from a randomized, clinical trial.

INTRODUCTION: We previously reported that a 6-day continuous peripheral nerve block reduces established postamputation phantom pain. To provide patients and providers with the information to best inform treatment decisions, here we reanalyze the data and present the results in a more patient-centered format. We also provide information on patient-defined clinically relevant benefits to facilitate evaluation of available studies and guide future trial design. METHODS: The original trial enrolled participants with a limb amputation and phantom pain who were randomized to receive a 6-day continuous peripheral nerve block(s) of either ropivacaine (n=71) or saline (n=73) in a double-masked fashion. Here we calculate the percentage of each treatment group that experienced a clinically relevant improvement as defined by previous studies as well as present what the participants of our study defined as small, medium, and large analgesic improvements using the 7-point ordinal Patient Global Impression of Change scale. RESULTS: Among patients who were given a 6-day ropivacaine infusion, 57% experienced at least a 2-point improvement on the 11-point numeric rating scale in their average and worst phantom pain 4 weeks postbaseline as compared with 26% (p<0.001) for average and 25% (p<0.001) for worst pain in patients given a placebo infusion. At 4 weeks, the percentage of participants rating their pain as improved was 53% for the active vs 30% for the placebo groups (95% CI 1.7 (1.1, 2.7), p=0.008). For all patients combined, the median (IQR) phantom pain Numeric Rating Scale improvements at 4 weeks considered small, medium, and large were 2 (0-2), 3 (2-5), and 5 (3-7), respectively. The median improvements in the Brief Pain Inventory interference subscale (0-70) associated with small, medium, and large analgesic changes were 8 (1-18), 22 (14-31), and 39 (26-47). CONCLUSIONS: Among patients with postamputation phantom pain, a continuous peripheral nerve block more than doubles the chance of a clinically relevant improvement in pain intensity. Amputees with phantom and/or residual limb pain rate analgesic improvements as clinically relevant similarly to other chronic pain etiologies, although their smallest relevant improvement in the Brief Pain Inventory was significantly larger than previously published values. TRIAL REGISTRATION NUMBER: NCT01824082.

Continuous femoral nerve blocks: the impact of catheter tip location relative to the femoral nerve (anterior versus posterior) on quadriceps weakness and cutaneous sensory block.

BACKGROUND: During a continuous femoral nerve block, the influence of catheter tip position relative to the femoral nerve on infusion characteristics remains unknown. METHODS: We inserted bilateral femoral perineural catheters in volunteers (ultrasound-guided, needle in-plane). Subjects' dominant side was randomized to have the catheter tip placed either anterior or posterior to the femoral nerve. The contralateral limb received the alternative position. Ropivacaine 0.1% was administered through both catheters concurrently for 6 hours (4 mL/h). Outcome measures included the maximum voluntary isometric contraction (MVIC) of the quadriceps femoris muscle and tolerance to cutaneous electrical current over to the distal quadriceps tendon. Measurements were performed at hour 0 (baseline), and on the hour until hour 9, as well as hour 22. The primary end point was the MVIC of the quadriceps at hour 6. RESULTS: As a percentage of the baseline measurement, quadriceps MVIC for limbs with anterior (n = 16) and posterior (n = 16) catheter tip placement did not differ to a statistically significant degree at hour 6 (mean [SD] 29% [26] vs 30% [28], respectively; 95% confidence interval: -22% to 20%; P = 0.931), or at any other time point. However, the maximum tolerance to cutaneous electrical current was higher in limbs with anterior compared with posterior catheter tip placement at hour 6 (20 [23] mA vs 6 [4] mA, respectively; 95% confidence interval: 1-27 mA; P = 0.035), as well as at hours 1, 7, 8, and 9 (P < 0.04). CONCLUSIONS: This study documents the significant (70%-80%) quadriceps femoris weakness induced by a continuous femoral nerve block infusion at a relatively low dose of ropivacaine (4 mg/h) delivered through a perineural catheter located both anterior and posterior to the femoral nerve. In contrast, an anterior placement increases cutaneous sensory block compared with a posterior insertion, without a concurrent relative increase in motor block.

Continuous femoral nerve blocks: varying local anesthetic delivery method (bolus versus basal) to minimize quadriceps motor block while maintaining sensory block.

BACKGROUND: Whether the method of local anesthetic administration for continuous femoral nerve blocks--basal infusion versus repeated hourly bolus doses--influences block effects remains unknown. METHODS: Bilateral femoral perineural catheters were inserted in volunteers (n = 11). Ropivacaine 0.1% was concurrently administered through both catheters: a 6-h continuous 5 ml/h basal infusion on one side and 6 hourly bolus doses on the contralateral side. The primary endpoint was the maximum voluntary isometric contraction (MVIC) of the quadriceps femoris muscle at hour 6. Secondary endpoints included quadriceps MVIC at other time points, hip adductor MVIC, and cutaneous sensation 2 cm medial to the distal quadriceps tendon in the 22 h after initiation of local anesthetic administration. RESULTS: Quadriceps MVIC for limbs receiving 0.1% ropivacaine as a basal infusion declined by a mean (SD) of 84% (19) compared with 83% (24) for those receiving 0.1% ropivacaine as repeated bolus doses between baseline and hour 6 (paired t test P = 0.91). Intrasubject comparisons (left vs. right) also reflected a lack of difference: the mean basal-bolus difference in quadriceps MVIC at hour 6 was -1.1% (95% CI -22.0-19.8%). The similarity did not reach the a priori threshold for concluding equivalence, which was the 95% CI decreasing within ± 20%. There were similar minimal differences in the secondary endpoints during local anesthetic administration. CONCLUSIONS: This study did not find evidence to support the hypothesis that varying the method of local anesthetic administration--basal infusion versus repeated bolus doses--influences continuous femoral nerve block effects to a clinically significant degree.

Continuous femoral versus posterior lumbar plexus nerve blocks for analgesia after hip arthroplasty: a randomized, controlled study.

BACKGROUND: Hip arthroplasty frequently requires potent postoperative analgesia, often provided with an epidural or posterior lumbar plexus local anesthetic infusion. However, American Society of Regional Anesthesia guidelines now recommend against epidural and continuous posterior lumbar plexus blocks during administration of various perioperative anticoagulants often administered after hip arthroplasty. A continuous femoral nerve block is a possible analgesic alternative, but whether it provides comparable analgesia to a continuous posterior lumbar plexus block after hip arthroplasty remains unclear. We therefore tested the hypothesis that differing the catheter insertion site (femoral versus posterior lumbar plexus) after hip arthroplasty has no impact on postoperative analgesia. METHODS: Preoperatively, subjects undergoing hip arthroplasty were randomly assigned to receive either a femoral or a posterior lumbar plexus stimulating catheter inserted 5 to 15 cm or 0 to 1 cm past the needle tip, respectively. Postoperatively, patients received perineural ropivacaine, 0.2% (basal 6 mL/hr, bolus 4 mL, 30-minute lockout) for at least 2 days. The primary end point was the average daily pain scores as measured with a numeric rating scale (0-10) recorded in the 24-hour period beginning at 07:30 the morning after surgery, excluding twice-daily physical therapy sessions. Secondary end points included pain during physical therapy, ambulatory distance, and supplemental analgesic requirements during the same 24-hour period, as well as satisfaction with analgesia during hospitalization. RESULTS: The mean (SD) pain scores for subjects receiving a femoral infusion (n = 25) were 3.6 (1.8) versus 3.5 (1.8) for patients receiving a posterior lumbar plexus infusion (n = 22), resulting in a group difference of 0.1 (95% confidence interval -0.9 to 1.2; P = 0.78). Because the confidence interval was within a prespecified -1.6 to 1.6 range, we conclude that the effect of the 2 analgesic techniques on postoperative pain was equivalent. Similarly, we detected no differences between the 2 treatments with respect to the secondary end points, with one exception: subjects with a femoral catheter ambulated a median (10th-90th percentiles) 2 (0-17) m the morning after surgery, in comparison with 11 (0-31) m for subjects with a posterior lumbar plexus catheter (data nonparametric; P = 0.02). CONCLUSIONS: After hip arthroplasty, a continuous femoral nerve block is an acceptable analgesic alternative to a continuous posterior lumbar plexus block when using a stimulating perineural catheter. However, early ambulatory ability suffers with a femoral infusion.

Ambulatory continuous peripheral nerve blocks to treat postamputation phantom limb pain: a multicenter, randomized, quadruple-masked, placebo-controlled clinical trial.

Phantom limb pain is thought to be sustained by reentrant neural pathways, which provoke dysfunctional reorganization in the somatosensory cortex. We hypothesized that disrupting reentrant pathways with a 6-day-long continuous peripheral nerve block reduces phantom pain 4 weeks after treatment. We enrolled patients who had an upper- or lower-limb amputation and established phantom pain. Each was randomized to receive a 6-day perineural infusion of either ropivacaine or normal saline. The primary outcome was the average phantom pain severity as measured with a Numeric Rating Scale (0-10) at 4 weeks, after which an optional crossover treatment was offered within the following 0 to 12 weeks. Pretreatment pain scores were similar in both groups, with a median (interquartile range) of 5.0 (4.0, 7.0) for each. After 4 weeks, average phantom limb pain intensity was a mean (SD) of 3.0 (2.9) in patients given local anesthetic vs 4.5 (2.6) in those given placebo (difference [95% confidence interval] 1.3 [0.4, 2.2], P = 0.003). Patients given local anesthetic had improved global impression of change and less pain-induced physical and emotional dysfunction, but did not differ on depression scores. For subjects who received only the first infusion (no self-selected crossover), the median decrease in phantom limb pain at 6 months for treated subjects was 3.0 (0, 5.0) vs 1.5 (0, 5.0) for the placebo group; there seemed to be little residual benefit at 12 months. We conclude that a 6-day continuous peripheral nerve block reduces phantom limb pain as well as physical and emotional dysfunction for at least 1 month.

Single-injection thoracic paravertebral block and postoperative analgesia after mastectomy: a retrospective cohort study.

BACKGROUND: The treatment of postoperative pain after mastectomy is an area of increasing interest, as this treatment option is now considered a standard of care for those affected by breast cancer. Thoracic paravertebral nerve block (tPVB) using local anesthetics administered before mastectomy can theoretically provide postoperative analgesia, thereby facilitating a more comfortable and shorter hospitalization. METHODS: In this retrospective cohort study, we aimed to determine the duration and degree to which tPVB provides postoperative analgesia in patients who underwent either unilateral or bilateral mastectomy (n = 182). We retrospectively examined the numeric rating scale (NRS) for pain scores recorded by nursing staff throughout individual patient hospitalizations, looking specifically at the following time points: arrival from the postanesthesia care unit to the surgical wards, noon on postoperative day 1 (POD1), and discharge. We also examined the number of days until patients were discharged from the hospital. RESULTS: Our results revealed a statistically significant decrease in NRS in pain scores for patients who had received a tPVB (n = 92) on arrival from the postanesthesia care unit to the surgical wards (mean NRS decrease of 1.9 points; 99% confidence interval [CI], -3.0 to -0.8; P < .001) but did not show statistically significant decreases in NRS for pain scores for patients at noon on POD1 (mean NRS decrease of 0.3 points at noon on POD1, P = .43) or at discharge (mean NRS decrease of 0.1 point at discharge, P = .65). Moreover, use of tPVB did not have an impact on time until discharge (average decrease of 0.5 hours; 95% CI, -6 to +5 hours, P = .87). CONCLUSIONS: Single-injection tPVB appears to provide meaningful postoperative analgesia in the immediate postoperative period after mastectomy but not after the first day of surgery.