Nonstimulating Catheter Research Articles

Efficacy of continuous femoral three-in-one nerve block using stimulating nerve catheter and non stimulating nerve catheter for postoperative analgesia in surgeries over thigh: a comparative study

Introduction: Continuous femoral analgesia provides extended pain relief for surgeries over thigh. Successful continuous peripheral nerve analgesia depends on catheter proximity to the target nerve and stimulating catheters may allow more accurate placement of catheters. Hence we conducted a study to compare the efficacy of stimulating nerve catheter and non stimulating nerve catheter in femoral 3-in-1 nerve block for postoperative analgesia. Materials and Methods: 60 ASA grade I & II patients of either sex between 18 to 65 years of age posted for total knee replacement surgery were randomly allocated into two groups: Group SC (stimulating catheter) and Group NSC(non stimulating catheter). All patients received subarachnoid block and after completion of surgery femoral catheter (stimulating/non stimulating depending on the group) was placed using peripheral nerve stimulator for postoperative analgesia. When spinal level regressed to T12 dermatomal level, Inj.Bupivacaine (0.25%) 20ml with Inj.Lignocaine (1%) 10ml was given. The patients were followed for next 24 hours from the time of first bolus. After the 1st bolus when the VRS score was ?3, intermittent boluses of Inj.Bupivacaine (0.25%) 15 ml with Inj.Fentanyl 0.5µg/kg were given. All patients received Inj. Paracetamol 20 mg/kg IV 6 hourly. In case patient still had VRS score ?3 then rescue analgesia in the form of Inj.Diclofenac sodium 1 mg/kg IV was given. Two groups were observed for total duration of sensory block (time from 1st bolus dose till the time VAS score was ?3); requirement of analgesic solution; requirement of rescue analgesia; and any complication or side effects. Results: Total duration of sensory block in group SC was 9.40±0.21 hours compared to 7.10±0.23 hours in group NSC (p=0.0001). Total requirement of analgesic solution was less in SC group in comparison to NSC group. No significant complication observed in either group. Conclusion: Stimulating nerve catheter provides lon

Comparative evaluation of the visibility and block characteristics of a stimulating needle and catheter vs an echogenic needle and catheter for sciatic nerve block with a low-frequency ultrasound probe

Background.Clear visibility of the needle and catheter tip is desirable to perform safe and successful ultrasound-guided peripheral nerve blocks. This can be challenging with deeper blocks in obese patients. This study compared the visibility of echogenic and non-echogenic block needles and catheters in proximal sciatic blocks when performed with a low-frequency curved probe. Methods.Seventy-eight patients undergoing total knee joint arthroplasty were randomized to receive an ultrasound-guided continuous sciatic nerve block using either a non-echogenic needle and stimulating catheter or an echogenic needle and echogenic non-stimulating catheter. Block needles in both groups were placed using both neurostimulation and ultrasound guidance, after which the catheter was positioned using either neurostimulation alone (Stimulating group) or imaging alone (Echogenic group). Three anaesthetists blinded to group allocation graded video clips recorded during the blocks for nerve, needle and catheter visibility. Performance characteristics and block parameters were also compared. Results.No significant differences between the two groups were observed with regard to needle or catheter visibility (P=0.516). The Stimulating group required more needle redirections (P=0.009), had a longer procedure time [Echogenic median 274 s vs Stimulating 344 s (P=0.016)], and resulted in greater patient discomfort (P=0.012). There were no significant differences between the two groups in terms of block onset or completion time. Conclusions.Use of echogenic needles and catheters reduced procedure time and patient discomfort compared with a stimulating catheter system. There were no differences in the visibility scores of the two systems. Clinical trial registristration.CTR Protocol ID: R-11-495, Clinical Trials.Gov ID: NCT 01492660.

A comparison of ultrasound alone vs ultrasound with nerve stimulation guidance for continuous femoral nerve block in patients undergoing total knee arthroplasty

Study ObjectiveTo compare analgesic efficacy of ultrasound (US) guidance alone and US guidance combined with nerve stimulation (NS) for continuous femoral nerve block (CFNB) in patients undergoing total knee arthroplasty (TKA). DesignProspective, randomized double-blind trial. SettingPostanesthesia care unit and general ward. PatientsFifty American Society of Anesthesiologist physical status I to II patients undergoing TKA under spinal anesthesia. InterventionsIn group A (n = 25), an 18-gauge Tuohy needle was directed at the lower mid-part of the femoral nerve, and a nonstimulating catheter was inserted through the needle under US guidance. In group B (n = 25), an 18-gauge Tuohy needle and stimulating catheter were directed to the lower part of femoral nerve under US guidance, and quadriceps muscle contraction was checked using NS. All patients received a 20-mL loading dose of 0.2% ropivacaine, a continuous infusion of 4 mL/h, and a 4-mL bolus of 0.2% ropivacaine with a lockout time of 60 minutes for patient-controlled analgesia. MeasurementsThe primary outcome was resting and exercising pain quality assessed by numeric rating scale. Other outcomes included procedure time for correct catheter placement, block failure rate, patient satisfaction for postoperative pain control, total dose of local anesthetic, additional opioid requirement, and adverse effects postoperatively. Main ResultsThere were no significant differences between groups in resting and exercising numeric rating scale. Procedure times were longer in group B than group A (P < .05). There were no significant differences between groups in block failure rate or other outcomes. ConclusionsUS-guided CFNB was associated with similar analgesic efficacy and block failure rate and reduced procedure time compared to US with NS guidance for CFNB in patients undergoing TKA.

Separation of stimulating catheters for continuous peripheral regional anesthesia during their removal - two case reports and a critical appraisal of the use of steel-coil containing stimulating catheters.

PurposeStimulating catheters are widely used for continuous peripheral nerve block techniques in regional anesthesia. The incidence of reported complications is somewhat similar to that for non-stimulating catheters. However, as many stimulating catheters contain a coiled steel wire for optimal stimulation, they may cause specific complications.Clinical featuresIn this report, we present two cases of complicated removals of stimulating catheters. During both removals, a part of the metal wire was left “decoiled” next to the supraclavicular and interscalene plexus, respectively. The strategies used to determine steel wire localization and a description of the successful removal of these steel wires are included in this report.ConclusionCatheter separation and problems with residual metal wire components of stimulating catheters seem to be a rare but specific problem during removal. Anesthesiologists should strictly avoid catheter shearing during insertion, adhere to the manufacturer’s instructions, and take care during catheter removal. Manufacturers should focus on technical solutions to avoid rare but relevant complications such as catheter tip decoiling and separation of stimulating catheters during removal.

Comparative effectiveness of infraclavicular and supraclavicular perineural catheters for ultrasound-guided through-the-catheter bolus anesthesia.

Using a through-the-needle local anesthetic bolus technique, ultrasound-guided infraclavicular perineural catheters have been shown to provide greater analgesia compared to supraclavicular catheters. A through-the-catheter bolus technique, which arguably "tests" the anesthetic efficacy of the catheter before initiating an infusion, has been validated for infraclavicular catheters but not supraclavicular catheters. This study investigated the through-the-catheter bolus technique for supraclavicular catheters and tested the hypothesis that infraclavicular catheters provide faster onset of brachial plexus anesthesia. Preoperatively, patients were randomly assigned to receive either a supraclavicular or an infraclavicular catheter using an ultrasound-guided nonstimulating catheter insertion technique with a mepivacaine bolus via the catheter and ropivacaine perineural infusion initiated postoperatively. The primary outcome was time to achieve complete sensory anesthesia in the ulnar and median nerve distributions. Secondary outcomes included procedural time, procedure-related pain and complications, and postoperative pain, opioid consumption, sleep disturbances, and motor weakness. Fifty patients were enrolled in the study; all but 2 perineural catheters were successfully placed per protocol. Twenty-one of 24 (88%) and 24 of 24 (100%) patients in the supraclavicular and infraclavicular groups, respectively, achieved complete sensory anesthesia by 30 minutes (P= .088). There was no difference in the time to achieve complete sensory anesthesia. Supraclavicular patients reported more sleep disturbances postoperatively, but there were no statistically significant differences in other outcomes. Both supraclavicular and infraclavicular perineural catheters using a through-the-catheter bolus technique provide effective brachial plexus anesthesia.

Randomised Comparison of an End-Hole, Triple-Hole and Novel Six-Hole Catheter for Continuous Interscalene Analgesia

Epidural analgesia studies and a recent continuous peripheral nerve block study suggest multi-hole perineural catheters perform better than end-hole catheters. Confounding catheter positioning issues limit interpretation of the latter study. One hundred and fifty-six patients receiving an anterolateral interscalene catheter for elective shoulder surgery were randomised to three groups: following out-of-plane ultrasound confirmation of the needle tip immediately lateral to the C5/6 roots, an end-hole (n=52), triple-hole (n=53) or six-hole (n=51) non-stimulating catheter was positioned 3 cm beyond the needle tip. Ropivacaine 0.375% 15 ml was administered preoperatively via the catheter before surgery under general anaesthesia. A ropivacaine 0.2% 2 ml/hour infusion with mandatory six-hourly, and on-demand hourly, 5 ml boluses was continued for >48 hours with tramadol available as rescue. Patients were questioned in the recovery room and at 24 hours for numerical rating pain score (0 to 10), ropivacaine bolus and tramadol consumption. The frequency of recovery room pain was similar between groups (P=0.75) and demonstrated strong evidence for equivalence at the 5% significance level. Neither time to first pain, "average" or "worst" pain during the first 24 hours, ropivacaine bolus or tramadol consumption significantly differed between groups. Catheter threading difficulty was more common for the square-tipped end-hole catheters (end-hole=19% versus triple-hole=6%, six-hole=0%, P >0.001). This study found no evidence to support catheter orifice configuration significantly affecting the quality of continuous peripheral nerve blockade. These findings are in contrast to epidural catheter studies, and suggest that anatomical factors have a significant bearing on whether multi-orifice catheters confer advantage over the single-orifice design.

Fluoroscopy Study of Peripheral Nerve Block Catheter Tip Movement?Its Clinical Implication in Guiding Catheter Adjustment

Background: Continuous peripheral nerve block catheter has been widely used clinically.A small percentage of catheters usually need adjustment after placement.However, there is no study on how to adjust catheter in the literature. Methods: Twelve fresh pork legs were randomly allocated into one of two groups, perineural catheter advanced 5 cm or less beyond needle tip (N=6), or more than 5 cm beyond needle tip (N=6). For both groups, ultrasound guided sciatic nerve block was performed with the “in-plane” approach.The anatomic landmarks and the locations of the sciatic nerve block equate to the Labat approach in humans. Thirty milliliter of normal saline was used to dissect the epineuron space before threading 20G soft non-stimulating catheter. The catheter was pulled back in onecentimeter increments at the level of the skin while the location of the tip of the catheter was identified by fluoroscopy after each centimeter pull back. The main outcome was the catheter tip movement. Results: The catheter tips advanced either cephalic or caudally without dominance trend, while most catheter tips located superficially to the needle tip (11 out of 12). In T 5 cm group, the catheter tip movement was initially 0.17 ± 0.11 cm per centimeter pull back, then increased to 0.25 ± 0.12 cm once the catheter tip was less than 5 cm beyond the initial depth of needle tip. Conclusions: We recommend that adjustment of the CPNC should base on the initial depth of the needle tip since the initial catheter tip movements among these over threaded catheters are very limited, and it would not be efficient in clinical practice to adjust peripheral nerve block catheter by pulling by centimeter increment.

The effect of stimulating versus conventional perineural catheters on postoperative analgesia following ultrasound-guided femoral nerve localization

Study Objective To test the hypothesis that, if the femoral nerve is correctly localized using ultrasound (US) guidance, the type of perineural catheter used has no effect on catheter success. Design Randomized controlled trial. Setting Post-anesthesia care unit of an academic teaching hospital. Patients 40 ASA physical status 1, 2, and 3 patients, ages 55-85 years, undergoing elective total knee arthroplasty. Interventions All patients received postoperative continuous femoral nerve blocks and a single injection sciatic nerve block. Nerve localization was accomplished using US guidance and electrical nerve stimulation so that the needle tip was visualized deep to the femoral nerve. Patients were randomized to receive either stimulating (Group SC) or nonstimulating catheters (Group NSC) in the usual manner for each device. Catheters were bolused with ropivacaine and an infusion commenced. Measurements The primary outcome was quality of analgesia (as measured by a numerical rating scale). Other outcomes included sensory block success rate, number of attempts and time required to localize the needle tip correctly, number of attempts and time required to place the perineural catheter, amount of local anesthetic and opioid use postoperatively, and degree of completion of preset postoperative rehabilitation goals. Main Results Quality of analgesia was similar at all time intervals. Rates of successful femoral block (95% vs 80%; P = 0.34) were similar between groups. Time required to position the catheter was greater in Group SC than Group NSC (3.45 ± 2.05 min vs 1.72 ± 0.88 min; P < 0.01). Conclusions Ultrasound guidance for needle localization prior to catheter insertion for femoral nerve block results in similar block characteristics between stimulating and nonstimulating catheters. The use of nonstimulating catheters avoids the technical challenges of stimulating catheters and does not require additional helpers.

Continuous Peripheral Nerve Block Catheter Infections in Combat-related Injuries: A Case Report of Five Soldiers from Operation Enduring Freedom/Operation Iraqi Freedom

Case series. Military medical facility providing acute care for soldiers injured while fighting in the war in Iraq and Afghanistan. To report a series of infections related to use of continuous peripheral nerve catheters for postoperative pain control in the military polytraumatic setting. The analysis of the above infections includes similarities and differences in infection patterns and attempts to clarify possible risk factors for such infections to include duration of catheter placement, type of catheter, preprocedural antibiotics, and tunnel vs nontunneled catheters. The goal of this analysis is to assist in the development of protocols that may prevent future catheter infections. Clinical data were obtained from five previously healthy male soldiers receiving acute care at Brooke Army Medical Center using continuous peripheral nerve catheters for postoperative pain for multiple and frequent procedures. In a total of six catheter infections, two were noted to have superficial skin infections while four were shown to have deep tissue involvement confirmed by imaging studies. All patients were started on initial or additional antibiotics after catheter removal. Three catheter infections, all with stimulating catheters, required surgical irrigation and debridement in the operating room. Continuous peripheral nerve catheters are not without complications and risks including infection. Duration of catheter use was the most significant factor with the development of a catheter-related infection in our series. This series also highlights how stimulating and nonstimulating catheter infections may present differently, as stimulating catheters may have a greater tendency to present as deep space infections with minimal superficial findings.

Comparison of Procedural Times for Ultrasound-Guided Perineural Catheter Insertion in Obese and Nonobese Patients

Perineural catheter insertion with ultrasound guidance alone has been described, but it remains unknown whether this new technique results in the same procedural time and success rate for obese and nonobese patients. We therefore tested the hypothesis that obese patients require more time for perineural catheter insertion compared to nonobese patients despite using ultrasound. Data from 5 previously published randomized clinical trials comparing ultrasound- and stimulation-guided perineural catheter insertion techniques were reviewed, and patients who received ultrasound-guided catheters were divided into 2 groups: obese (body mass index ≥30 kg/m(2)) and nonobese (body mass index <30 kg/m(2)). A standardized ultrasound-guided nonstimulating catheter technique was used with mepivacaine, 1.5% (40 mL), as the initial bolus via the placement needle for the primary surgical nerve block. The primary outcome was the procedural time for perineural catheter insertion. Secondary outcomes included block efficacy, procedure-related pain, fluid leakage, vascular puncture, and catheter dislodgment. A sample of 120 patients was identified: 51 obese and 69 nonobese. All obese patients had successful catheter placement compared to 68 of 69 (98%) nonobese patients (P = .388). The time for perineural catheter insertion [median (10th-90th percentiles)] was 7 (4-12) minutes for obese patients versus 7 (4-15) minutes for nonobese patients (P = .732). There were no statistically significant differences in other secondary outcomes. On the basis of this retrospective analysis, perineural catheter insertion is not prolonged in obese patients compared to nonobese patients when an ultrasound-guided technique is used. However, these results are only suggestive and require confirmation through prospective study.

Catheter Orifice Configuration Influences the Effectiveness of Continuous Peripheral Nerve Blockade

We investigated perineural catheter threading distance and orifice configuration during continuous interscalene analgesia. One hundred fifty-three patients receiving an anterolateral interscalene catheter (catheter needle and nerve/plexus in a similar alignment) for elective shoulder surgery were randomized to 1 of 3 groups: following out-of-plane ultrasound confirmation of the needle tip immediately lateral to the C5/6 roots, a nonstimulating catheter was blindly advanced 0.5 cm (end-hole; n = 50), 2.5 cm (multiorifice; n = 50) or 5 cm (multiorifice; n = 53) beyond the needle tip. Ropivacaine 0.75% + lidocaine 1% (50:50) 20 mL was administered preoperatively via the catheter before surgery under general anesthesia. A ropivacaine 0.2% 2 mL/hr elastomeric infusion with mandatory 6 hourly (and on demand) 5-mL boluses was continued for more than 48 hrs with tramadol available as rescue. Patients were questioned in the recovery room, at 24 and 48 hrs for numerical rating pain score (0-10), ropivacaine bolus, and tramadol consumption. Patients were more frequently pain-free in the recovery room in the multiorifice 2.5 and 5 cm groups compared with the end-hole 0.5 cm group (94%, 91% vs 66%; P < 0.001). During the first 24 hrs, the end-hole group demonstrated an earlier time to first pain (median, 10 vs17, 15 hrs; P < 0.001), higher "average pain" (median, 3 vs 1, 2, P = 0.004), and more ropivacaine bolus (median, 5 vs 3, 3; P < 0.001) and tramadol consumption (P = 0.01). Groups 2.5 and 5 cm did not significantly differ in any outcomes. These results suggest that multiorifice catheters provide superior intermittent bolus continuous peripheral nerve blockade compared with end-hole catheters. For anterolateral approach interscalene catheter placement, there is minimal benefit, either way, to 2.5- or 5-cm blind catheter advancement.

A Randomized Comparison of Infraclavicular and Supraclavicular Continuous Peripheral Nerve Blocks for Postoperative Analgesia

Although the efficacy of single-injection supraclavicular nerve blocks is well established, no controlled study of continuous supraclavicular blocks is available, and their relative risks and benefits remain unknown. In contrast, the analgesia provided by continuous infraclavicular nerve blocks has been validated in randomized controlled trials. We therefore compared supraclavicular with infraclavicular perineural local anesthetic infusion following distal upper-extremity surgery. Preoperatively, subjects were randomly assigned to receive a brachial plexus perineural catheter in either the infraclavicular or supraclavicular location using an ultrasound-guided nonstimulating catheter technique. Postoperatively, subjects were discharged home with a portable pump (400-mL reservoir) infusing 0.2% ropivacaine (basal rate of 8 mL/hr; 4-mL bolus dose; 30-min lockout interval). Subjects were followed up by telephone on an outpatient basis. The primary outcome was the average pain score on the day after surgery. Sixty subjects were enrolled, with 31 and 29 randomized to receive an infraclavicular and supraclavicular catheter, respectively. All perineural catheters were successfully placed per protocol. Because of protocol violations and missing data, an intention-to-treat analysis was not used; rather, only subjects with catheters in situ and whom we were able to contact were included in the analyses. The day after surgery, subjects in the infraclavicular group reported average pain as median of 2.0 (10th-90th percentiles, 0.5-6.0) compared with 4.0 (10th-90th percentiles, 0.6-7.7) in the supraclavicular group (P = 0.025). Similarly, least pain scores (numeric rating scale) on postoperative day 1 were lower in the infraclavicular group compared with the supraclavicular group (0.5 [10th-90th percentiles, 0.0-3.5] vs 2.0 [10th-90th percentiles, 0.0-4.7], respectively; P = 0.040). Subjects in the infraclavicular group required less rescue oral analgesic (oxycodone, in milligrams) for breakthrough pain in the 18 to 24 hrs after surgery compared with the supraclavicular group (0.0 [10th-90th percentiles, 0.0-5.0] vs 5.0 [10th-90th percentiles, 0.0-15.0], respectively; P = 0.048). There were no statistically significant differences in other secondary outcomes. A local anesthetic infusion via an infraclavicular perineural catheter provides superior analgesia compared with a supraclavicular perineural catheter.

Preliminary Experience With a Novel Ultrasound-Guided Supraclavicular Perineural Catheter Insertion Technique for Perioperative Analgesia of the Upper Extremity

Brachial plexus perineural catheters provide specific analgesia for upper extremity surgery. Although single-injection ultrasound-guided supraclavicular blocks have been described, little is known about the efficacy of perineural catheters inserted using this approach. We present our experience with ultrasound-guided supraclavicular perineural catheters for distal upper extremity surgery. In this case series, 10 patients who underwent upper extremity surgery for orthopedic trauma at a tertiary care university hospital received a supraclavicular brachial plexus perineural catheter for postoperative pain management. In all patients, a nonstimulating catheter was inserted using an ultrasound-guided technique with the catheter tip remaining under direct vision until placement needle withdrawal. Postoperatively, a perineural ropivacaine, 0.2%, infusion was administered at a basal rate of 6 mL/h with a patient-controlled bolus of 4 mL and a lockout interval of 30 minutes. Of the 10 patients, all had successful perineural catheter placement. Patients required a median (range) of 0 (0-100) μg of fentanyl for catheter insertion analgesia. There were no vascular punctures or other direct procedure-related complications. Catheters were maintained for a median (range) of 4 (2-5) days in both hospitalized and ambulatory patients. Median (range) pain scores on postoperative days 1 and 2 were 5 (0-7) and 4 (3-6), respectively, on a numeric rating scale. Three patients' catheters were removed by patient request or dislodged on postoperative day 1. Supraclavicular brachial plexus perineural catheter insertion using ultrasound guidance is feasible and deserves further study with a randomized controlled trial comparing this relatively new technique with more established approaches.

Comparative efficacy of ultrasound-guided and stimulating popliteal-sciatic perineural catheters for postoperative analgesia

PurposePerineural catheter insertion using ultrasound guidance alone is a relatively new approach. Previous studies have shown that ultrasound-guided catheters take less time to place with high placement success rates, but the analgesic efficacy compared with the established stimulating catheter technique remains unknown. We tested the hypothesis that popliteal-sciatic perineural catheter insertion relying exclusively on ultrasound guidance results in superior postoperative analgesia compared with stimulating catheters.MethodsPreoperatively, subjects receiving a popliteal-sciatic perineural catheter for foot or ankle surgery were assigned randomly to either ultrasound guidance (bolus via needle with non-stimulating catheter insertion) or electrical stimulation (bolus via catheter). We used 1.5% mepivacaine 40 mL for the primary surgical nerve block and 0.2% ropivacaine (basal 8 mL·hr−1; bolus 4 mL; 30 min lockout) was infused postoperatively. The primary outcome was average surgical pain on postoperative day one.ResultsForty of the 80 subjects enrolled were randomized to each treatment group. One of 40 subjects (2.5%) in the ultrasound group failed catheter placement per protocol vs nine of 40 (22.5%) in the stimulating catheter group (P = 0.014). The difference in procedural duration (mean [95% confidence interval (CI)]) was −6.48 (−9.90 - −3.05) min, with ultrasound requiring 7.0 (4.0-14.1) min vs stimulation requiring 11.0 (5.0-30.0) min (P < 0.001). The average pain scores of subjects who provided data on postoperative day one were somewhat higher for the 33 ultrasound subjects than for the 26 stimulation subjects (5.0 [1.0-7.8] vs 3.0 [0.0-6.5], respectively; P = 0.032), a difference (mean [95%CI]) of 1.37 (0.03-2.71).ConclusionFor popliteal-sciatic perineural catheters, ultrasound guidance takes less time and results in fewer placement failures compared with stimulating catheters. However, analgesia may be mildly improved with successfully placed stimulating catheters. Clinical trial registration number NCT00876681.

The Effect of Stimulating Versus Nonstimulating Catheter Techniques for Continuous Regional Anesthesia

Stimulating catheters provide feedback regarding the location of the catheter tip in relation to the target nerve or plexus. There is debate concerning whether stimulating catheters may reduce the failure rate of postoperative analgesia or whether they may enhance functional recovery by providing superior and more reliable postoperative analgesia. Studies comparing the effect of stimulating versus nonstimulating catheters for postoperative analgesia were systematically and independently searched by 2 authors. Eleven randomized controlled studies could be included in this review. One trial was performed in volunteers; the others were clinical trials in patients. Five trials were performed in patients scheduled for a femoral nerve catheter, 4 for a distal sciatic nerve catheter, 1 in patients receiving an interscalene nerve catheter, and 1 in patients with an infraclavicular brachial plexus block. A standard quantitative analysis was deemed inappropriate because of considerable heterogeneity regarding the investigated outcome parameters. A semiquantitative review revealed that efficacy (judged by reduction in the need for rescue analgesics, complete surgery block, or median effective local anesthetic volume blocking the nerve) suggests improvement in stimulating catheters compared with nonstimulating catheters. Patient satisfaction as well as functional recovery was poorly investigated, so no conclusions could be drawn. Published reports of randomized controlled trials provide evidence for a better analgesic effect from stimulating catheters. Future trials should be conducted in a standardized manner with uniform reporting of outcomes, which may facilitate future quantitative analysis.

A Trainee-Based Randomized Comparison of Stimulating Interscalene Perineural Catheters With a New Technique Using Ultrasound Guidance Alone

Compared to the well-established stimulating catheter technique, the use of ultrasound guidance alone for interscalene perineural catheter insertion is a recent development and has not yet been examined in a randomized fashion. We hypothesized that an ultrasound-guided technique would require less time and produce equivalent results compared to electrical stimulation (ES) when trainees attempt interscalene perineural catheter placement. Preoperatively, patients receiving an interscalene perineural catheter for shoulder surgery were randomly assigned to an insertion protocol using either ultrasound guidance with a nonstimulating catheter or ES with a stimulating catheter. The primary outcome was the procedural duration (in minutes), starting when the ultrasound probe (ultrasound group) or catheter insertion needle (ES group) first touched the patient and ending when the catheter insertion needle was removed after catheter insertion. All ultrasound-guided catheters (n = 20) were placed successfully and resulted in surgical anesthesia versus 85% of ES-guided catheters (n = 20; P = .231). Perineural catheters placed by ultrasound (n = 20) took a median (10th-90th percentiles) of 8.0 (5.0-15.5) minutes compared to 14.0 (5.0-30.0) minutes for ES (n = 20; P = .022). All catheters placed according to the protocol in both treatment groups resulted in a successful nerve block; however, 1 patient in the ES group had local anesthetic spread to the epidural space. There was 1 vascular puncture using ultrasound guidance compared to 5 in the ES-guided catheter group (P = .182). Trainees using a new ultrasound-guided technique can place inter-scalene perineural catheters in less time compared to a well-documented technique using ES with a stimulating catheter and can produce equivalent results.

Ultrasound Guidance Versus Electrical Stimulation for Femoral Perineural Catheter Insertion

Continuous femoral nerve blocks provide potent analgesia and other benefits after knee surgery. Perineural catheter placement techniques using ultrasound guidance and electrical stimulation (ES) have been described, but the optimal method remains undetermined. We tested the hypothesis that ultrasound guidance alone requires less time for femoral perineural catheter insertion and produces equivalent results compared with ES alone. Preoperatively, patients receiving a femoral perineural catheter for knee surgery were randomly assigned to either ultrasound guidance with a nonstimulating catheter or ES with a stimulating catheter. The primary outcome was the catheter placement procedure time (minutes) starting when the ultrasound transducer (ultrasound group) or catheter insertion needle (ES group) first touched the patient and ending when the catheter insertion needle was removed after catheter insertion. Perineural catheters placed with ultrasound guidance (n = 20) took a median (10th-90th percentiles) of 5.0 (3.9-10.0) minutes compared with 8.5 (4.8-30.0) minutes for ES (n = 20; P = .012). All ultrasound-guided catheters were placed according to the protocol (n = 20) versus 85% of ES-guided catheters (n = 20; P = .086). Patients in the ultrasound group had a median procedure-related discomfort score of 0.5 (0.0-3.1) compared with 2.5 (0.0-7.6) for the ES group (P = .015). There were no vascular punctures with ultrasound guidance versus 4 in the ES group (P = .039). Placement of femoral perineural catheters takes less time with ultrasound guidance compared with ES. In addition, ultrasound guidance produces less procedure-related pain and prevents inadvertent vascular puncture.

Electrical Stimulation Versus Ultrasound Guidance for Popliteal-Sciatic Perineural Catheter Insertion

Sciatic perineural catheters via a popliteal fossa approach and subsequent local anesthetic infusion provide potent analgesia and other benefits after foot and ankle surgery. Electrical stimulation (ES) and, more recently, ultrasound (US)-guided placement techniques have been described. However, because these techniques have not been compared in a randomized fashion, the optimal method remains undetermined. Therefore, we tested the hypotheses that popliteal-sciatic perineural catheters placed via US guidance require less time for placement and produce equivalent results, as compared with catheters placed using ES. Preoperatively, subjects receiving a popliteal-sciatic perineural catheter for foot and/or ankle surgery were randomly assigned to either the ES with a stimulating catheter or US-guided technique with a nonstimulating catheter. The primary end point was catheter insertion duration (in minutes) starting when the US transducer (US group) or catheter-placement needle (ES group) first touched the patient and ending when the catheter-placement needle was removed after catheter insertion. All US-guided catheters were placed per protocol (n = 20), whereas only 80% of stimulation-guided catheters could be placed per protocol (n = 20, P = 0.106). All catheters placed per protocol in both groups resulted in a successful surgical block. Perineural catheters placed by US took a median (10th-90th percentile) of 5.0 min (3.9-11.1 min) compared with 10.0 min (2.0-15.0 min) for stimulation (P = 0.034). Subjects in the US group experienced less pain during catheter placement, scoring discomfort a median of 0 (0.0-2.1) compared with 2.0 (0.0-5.0) for the stimulation group (P = 0.005) on a numeric rating scale of 0 to 10. Placement of popliteal-sciatic perineural catheters takes less time and produces less procedure-related discomfort when using US guidance compared with ES.

Ultrasound Guidance Versus Electrical Stimulation for Infraclavicular Brachial Plexus Perineural Catheter Insertion

Electrical stimulation (ES)- and ultrasound-guided placement techniques have been described for infraclavicular brachial plexus perineural catheters but to our knowledge have never been previously compared in a randomized fashion, leaving the optimal method undetermined. We tested the hypothesis that infraclavicular catheters placed via ultrasound guidance alone require less time for placement and produce equivalent results compared with catheters placed solely via ES. Preoperatively, patients receiving an infraclavicular perineural catheter for distal upper extremity surgery were randomly assigned to either ES with a stimulating catheter or ultrasound guidance with a nonstimulating catheter. The primary outcome was the catheter insertion duration (minutes) starting when the ultrasound transducer (ultrasound group) or catheter placement needle (stimulation group) first touched the patient and ending when the catheter placement needle was removed after catheter insertion. Perineural catheters placed with ultrasound guidance took a median (10th-90th percentile) of 9.0 (6.0-13.2) minutes compared with 15.0 (4.9-30.0) minutes for stimulation (P < .01). All ultrasound-guided catheters were successfully placed according to the protocol (n = 20) versus 70% in the stimulation group (n = 20; P < .01). All ultrasound-guided catheters resulted in a successful surgical block, whereas 2 catheters placed by stimulation failed to result in surgical anesthesia. Six catheters (30%) placed via stimulation resulted in vascular punctures compared with none in the ultrasound group (P < .01). Procedure-related pain scores were similar between groups (P = .34). Placement of infraclavicular perineural catheters takes less time, is more often successful, and results in fewer inadvertent vascular punctures when using ultrasound guidance compared with ES.

A Randomized, Observer-Blinded Determination of the Median Effective Volume of Local Anesthetic Required to Anesthetize the Sciatic Nerve in the Popliteal Fossa for Stimulating and Nonstimulating Perineural Catheters

Stimulating perineural catheters are developed to overcome technical problems of nonstimulating catheters, but their efficacy remains controversial. However, no volume-response study has compared success rates between stimulating and nonstimulating catheters. This study of stimulating versus nonstimulating catheters compares the minimal effective volume required to successfully block the sciatic nerve in 50% of patients scheduled for unilateral hallux valgus repair. Patients underwent unilateral sciatic nerve block in the popliteal fossa with mepivacaine 1.5%, using either a stimulating (STIM group) or a nonstimulating (NONSTIM group) popliteal catheter. The volume of mepivacaine started at 20 mL and was increased or decreased by increments of 2 mL in subsequent patients, depending on the efficacy of the block in the previous patient, using the technique of up-down sequential allocation described by Dixon (Neurosci Biobehav Rev. 1991;15:47-50). Minimum effective volumes of local anesthetic were calculated using the formula of Dixon. Efficacy of block was defined by a complete sensory-motor block in the cutaneous distributions of the sciatic nerve associated with a pain-free surgery. Twenty-four patients were included in each group. Median effective volume blocking the sciatic nerve was significantly lower (P < 0.05) in the STIM group (2.7 mL; 95% confidence interval, 0.5-4.9 mL) compared with the NONSTIM group (16.6 mL; 95% confidence interval, 15.2-18.0 mL). Stimulating popliteal catheters dramatically decrease the volume required to block the sciatic nerve in 50% of patients, compared with nonstimulating catheters.