Stimulating Catheters Research Articles

Perineural Entrapment of an Interscalene Stimulating Catheter

A patient undergoing elective total shoulder arthroplasty had an Arrow Stimucath™ (Arrow International Reading, PA, USA) stimulating catheter inserted in the region of the interscalene brachial plexus using an ultrasound-guided in-plane approach. There was subsequent difficulty in removing the catheter and traction was associated with painful paraesthesia in the patient's thumb. Plain X-ray revealed a hook-shaped deformity of the tip and surgical exploration was required to remove the catheter, the tip of which appeared to be trapped within the sheath of the brachial plexus. We speculate that the mechanism for entrapment in this case was deformation of the catheter tip into a hook-like shape. The subsequent catheter-neural interaction prevented asymptomatic removal. We recommend that removal of peripheral nerve catheters be attempted only after resolution of sensory block so as to enable patients to report pain or paraesthesia. Imaging with ultrasound or X-rays may help ascertain catheter tip location and confirm whether deformity is present. We also recommend a low threshold for proceeding to surgical extraction, particularly if neurological symptoms are present.

The Sensitivity of Motor Responses for Detecting Catheter-Nerve Contact During Ultrasound-Guided Femoral Nerve Blocks with Stimulating Catheters

We determined the sensitivity of motor responses evoked by stimulating catheters in determining catheter-nerve contact using ultrasonography as reference. Femoral nerves were contacted using stimulating catheters under ultrasonography scanning in 25 patients. The output current was increased from its minimum until quadriceps muscle contraction occurred. The sensitivity of the motor response in determining catheter-nerve contact was calculated using 0.5 mA as current threshold. The current required for catheter stimulation to evoke a motor response ranged between 0.18 and 2.0 mA. Muscle contraction in response to 0.5 mA occurred in 16 of 25 subjects. The sensitivity of motor response for nerve stimulation was 64% (95% confidence interval: 0.43, 0.82). The absence of muscle responses at a stimulating current≤0.5 mA does not necessarily indicate the absence of catheter-nerve contact.

Tip adhesions complicate infraclavicular catheter removal

To the Editor, Continuous peripheral nerve blocks (CPNBs) are a versatile tool for ambulatory anesthesia because they can offer both surgical anesthesia as well as prolonged postoperative analgesia. For orthopedic procedures in particular, they reduce the need for general anesthesia and opioids with a decreased incidence of nausea and vomiting. However, there are complications with CPNBs that give rise to concern including migration, kinking, knotting, dislodgement, site infection, and nerve injury. In a previous report, we described additional complications due to shearing in five patients who received continuous nerve blocks with stimulating catheters. Those reported complications suggested a dilemma in placing continuous stimulating perineural catheters on an ambulatory basis, i.e., in each case, a return trip to the hospital was required for removal. In this regard, we report tissue adhesions complicating removal of a stimulating catheter. The authors consulted the institutional Ethics Review Board and obtained approval for publication in the Journal. A 46-yr-old male (American Society of Anesthesiologists physical status II, body mass index 29 kg m) was scheduled for right wrist tumour re-excision and splitthickness skin graft. His medical history was negative except for prior removal of an eccrine tumour on his right wrist. After obtaining the patient’s written consent, an ultrasound-guided infraclavicular CPNB with a 19G StimCath (Arrow International, Reading, PA, USA) was performed for postoperative analgesia. Ropivacaine 0.2% was infused at 5 mL hr with a patient-controlled analgesia dose of 5 mL every hour. The patient was discharged from hospital the following day. It is routine practice at our institution to discontinue the catheter within 72 hr of placement, which is usually the duration of the volume in the local anesthesia reservoir. In this case, the patient called on postoperative day (POD) 4 with a complaint concerning difficulty removing his catheter. He lived two hours distance from our medical centre and did not want the added drive during the weekend to have the catheter removed. Consequently, the attempted removal at home occurred on POD 4 when the infusion device was empty. During the procedure, the white-coloured polyurethane sheath separated from the coiled omni-port stainless steel tip. Ultimately, successful removal the catheter was achieved on POD 6 by applying steady traction on the catheter and using a reverse Seldinger technique. The patient did not complain of paresthesia during the procedure although the catheter tip was enveloped with tissue (Figure); the pathological diagnosis was benign fibrinous tissue. Since the patient was observed overnight prior to discharge and, possibly more important, because he declined to return to the hospital on POD 4 when he encountered difficulty with removal, the catheter remained in place without local anesthetic infusing for approximately 48 hr. This scenario mimics the findings of Buckenmaier et al. where catheters were left in vivo in rats without local anesthetic infusions. While there was a large amount of fibrous tip adhesion found upon catheter removal, it is not known whether it occurred over the course of the almost 48 hr that the local anesthetic was not infusing or whether a portion of it occurred as early as during the continuous infusion. The tip adhesion data from Buckenmaier et al. were collected following seven days of catheter maintenance. Our case suggests that fibrous adhesions may occur R. Duclas Jr, MD (&) C. B. Robards, MD B. L. Ladie, MD S. R. Clendenen, MD Mayo Clinic, Jacksonville, FL, USA e-mail: rduclasjr@gmail.com

Difficult-to-Treat or Resistant Hypertension: Etiology, Pathophysiology, and Innovative Therapies

Despite the many therapeutic options available today for the treatment of hypertension, a sizable number of patients still remain resistant to treatment. The prevalence of resistant hypertension in the general population under optimal conditions is about 3–5%. Although several factors and conditions can be identified and corrected a percentage of hypertensive patients remain with unacceptably high blood pressure levels. The high prevalence of hypertension in the general population renders this small percentage significant, in terms of actual patient numbers. This special issue of the journal expoars a whole spectrum of topics related to resistant hypertension: several articles address pathophysiolog and secondary causes of resistant hypertension and modern approaches to therapy. Of interest is the referance to the newer interventional approaches, that is, Baroreceptor stimulation therapy and catheter based sympathetic renal denervation.

Complications of peripheral nerve catheter removal at home: case series of five ambulatory interscalene blocks

The placement of continuous peripheral nerve catheters on an ambulatory basis is increasing and is routine at our institution. There are few reports of complications associated with peripheral nerve catheter removal in the literature. Described herein is a case series of five patients where complications related to catheter withdrawal were observed. A stimulating catheter with a stainless steel coil surrounded by polyurethane (19-G, 60-cm) exhibited shearing when removal proved difficult in five patients. In four cases, catheter removal by the patients was not possible, requiring them to return to hospital for management. No long-term sequelae were observed in any patient. There can be various causes for difficulty with catheter removal, such as a technical aspect of catheter placement, catheter design, tissue reaction at the catheter site, or a combination thereof. The majority of complications related to outpatient perineural catheters can be handled over the telephone, but our case series may highlight a potential management dilemma in placing continuous stimulating perineural catheters on an ambulatory basis.

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.

Removal of a knotted stimulating femoral nerve catheter using a saline bolus injection

Stimulating peripheral nerve catheters have become increasingly popular as part of postoperative multimodal analgesia for total knee arthroplasty. We describe a case of a successful nonsurgical removal of a knotted stimulating femoral nerve catheter after saline expansion of the catheter pocket at the bedside. A 65-year-old female underwent total knee arthroplasty under combined spinal epidural anesthesia. Postoperatively, a stimulating femoral nerve catheter was placed without complication. The catheter was threaded 12 cm past the needle tip with minimal resistance. Function of the catheter was verified by loss of pinprick sensation in the femoral nerve distribution and excellent analgesic efficacy was achieved. The first attempt at catheter removal was unsuccessful. Thigh flexion and rotation also failed to facilitate catheter removal. The catheter was then left to continuous tension for 6 hours, but further attempts at removal remained unsuccessful. Under ultrasound visualization, 10 mL of saline was injected through the catheter with moderate resistance and without patient discomfort, after which the catheter was removed using minimal tension. The catheter was intact but had a single knot at the distal end of the catheter. We present a rare case of a knotted stimulating catheter in which the use of a saline bolus to dilate the catheter pocket proved to be successful after other simple methods of catheter removal had failed. Given the simple nature of this technique, it can be attempted at the bedside before more invasive procedures are planned.

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.

Super-selective electrical stimulation of the left ventricle via a miniaturized magnetized stimulation wire: proof of concept study

Cardiac resynchronization therapy provides a treatment option for patients with congestive heart failure. Electrodes are usually advanced via the cardiac venous system (CVS). Placement is often hampered by small vessel diameter or tortuosity. The aim of this study was to develop and test a magnetized stimulation wire (MSW) capable of being navigated into small and tortuous CVS branches. Therefore, a conventional guide wire with a permanent magnet and a single stimulation electrode at its tip was coated with iridium oxide at the distal end and insulated except for the very tip (coating thickness: 500 nm, active uncoated area: 10 mm(2)). The MSW was designed to allow for a remote magnetic steering using a magnetic navigation system (MN) (Stereotaxis™). After in vitro testing of the electrical properties, the MSW was tested in an animal model (n=6 sheep): the MSW was placed in a CVS side branch and navigation characteristics of the MSW were determined. The effective (unipolar) pacing threshold was 4.9±2.4 V (at 2 ms pulse width). The rheobase was 1.89±0.44 V and the chronaxie time was 0.75±0.7 ms. The MSW could be navigated into small CVS branches with reasonable MN properties. This could allow stimulation at CVS sites currently not accessible for conventional stimulation catheters or electrodes.

Various Possible Positions of Conventional Catheters Around the Femoral Nerve Revealed by Neurostimulation

In continuous femoral nerve blocks, the various perineural positions of the tip of a conventional catheter and their clinical implication are not completely known.We used stimulating catheters to explore the relationship of catheter tip to nerve. American Society of Anesthesiologists physical status IYII patients scheduled for total knee arthroplasty were administered effective single-shot blocks of the obturator and sciatic nerves using ropivacaine 0.5% 10 and 20 mL, respectively. Continuous femoral blocks were performed using stimulating catheters, which were advanced blindly. Neurostimulation via catheter was performed but was masked from the investigators' sight. Before general anesthesia was induced for surgery, 5 mL of ropivacaine 0.2% was administered through the femoral nerve catheter, followed by infusion (5 mL/hr). Visual analog scale (VAS) score at rest was recorded on admission to the postanesthesia care unit. Characteristics of neurostimulation via the catheters were analyzed. Thirty-three patients were studied. Motor responses to stimulation via the catheters were obtained at 1 mA or less in 55% of patients and at greater than 1 mA in 45%. Various motor responses involved twitches of the pectineus (12%), sartorius (18%), or quadriceps (48%) muscles, or no muscular twitch up to 5 mA (22%). Catheter-induced motor response at 1 mA or less was associated with median values of VAS scores lower than those at greater than 1 mA (0 vs 30 mm; P = 0.008). The effectiveness of a continuous femoral block depends on neurostimulation characteristics, which likely correspond to various possible catheter tip positions. Conventional catheters provide no information on this issue. These results suggest that better VAS scores are attainable by placing catheters with neurostimulation guidance.

Pain therapy using stimulating catheters after total knee arthroplasty

Epidural analgesia and continuous femoral nerve blocks are often used for pain therapy after total knee arthroplasty. The additional use of a continuous sciatic nerve block is controversially discussed. To avoid the problem of inaccurate placement a stimulating catheter may be useful. The aim of this study was to compare the effectiveness of a continuous femoral nerve block with an additional continuous sciatic nerve block for improved functional recovery and pain relief. An open randomized prospective controlled study was carried out with 54 patients to receive either a stimulating catheter placed in the femoral nerve sheath or two stimulating catheters placed in the femoral and in the sciatic nerve sheath or an epidural analgesia. Pain was recorded with the visual analogue scale at rest and with passive motion of the knee during the first 3 postoperative days. The angle of nearly pain-free bending of the knee, side effects and opioid consumption were recorded. The reported pain scores and opioid consumption did not differ significantly between the groups. However, functional recovery up to the third postoperative day was significantly worse in the femoral catheter group. Using stimulating catheters for pain therapy the three methods are largely comparable and other parameters should be used for individual selection.

Two Unusual Cases of Urinary Incontinence During Continuous Sciatic Nerve Block with Stimulating Catheters

One of the advantages of lower extremity peripheral nerve blocks compared with neuroaxial Neuraxial techniques is the lack of effect on urinary function. We report two cases of urinary incontinence during continuous sciatic nerve block with stimulating catheters placed using the posterior gluteal Labat approach. The two patients were able to control micturition 6 h after the catheter was removed.

Stimulating nerve catheters in regional anaesthesia

Summary The practice of regional anaesthesia has evolved from mechanically stimulating a nerve with a needle and thereby eliciting paraesthesia to the fine art of using state-of-the art electrolocation using peripheral nerve stimulators and insulated needles. The stimulating nerve catheter is a very useful addition to the armamentarium of the regional anaesthesia practitioner. The stimulating nerve catheter makes it possible to verify the perineural location before delivering targeted continuous infusion of local anaesthetic for extended pain relief. The increasing use of ultrasound in echolocation of neural structures has added a new dimension to the popularity of peripheral nerve blocks.

Migration of a Thoracic Epidural Catheter into the Intercostal Space via the Intervertebral Foramen

We describe a documented migration of a thoracic epidural catheter into the thoracic cage in a 5-wk-old with DiGeorge's syndrome and an uncorrected acyanotic Tetralogy of Fallot who underwent laparotomy for malrotation, gastric fundoplication, and gastrostomy tube insertion under combined general and epidural anesthesia. A 20-gauge stimulating catheter was inserted caudally and advanced cephalad to the thoracic level while applying a low electrical current (1-10 mA) to confirm epidural placement at approximately T5-6. Despite good pain control through the third postoperative day, using an epidural infusion of bupivacaine 0.1% at 1-1.2 mL/h, radiography demonstrated catheter migration into the seventh intercostal space.

Continuous peripheral nerve blocks in clinical practice

The present review highlights new insights into indications and guidance during procedures for continuous peripheral nerve blocks. Continuous peripheral nerve blocks consistently provide better analgesia than traditional systemic opioid-based analgesia. The literature shows that continuous peripheral nerve blocks prolong site-specific local anesthetic delivery in the outpatient setting, allow optimal analgesia, have minimal side effects, and avoid premature regression of an analgesic block. Furthermore, an improvement in patients' health-related quality of life or outcome benefits has been demonstrated. It appears that continuous peripheral nerve blocks are generally superior to intraarticular local anesthetic infusion for immediate postoperative pain, but new data demonstrate that, apart from a multimodal analgesia regimen, periarticular and intraarticular application of local anesthetics can improve early postoperative analgesia and mobilization. Finally, it seems that, only for interscalene and popliteal sciatic nerve blocks, the use of stimulating catheters slightly decreases visual analog scale scores for postoperative pain and intravenous opioid rescue analgesia. Ultrasound guidance offers the potential advantage to confirm catheter tip location. Continuous peripheral nerve blocks are essential in the perioperative anesthetic management of in-hospital or ambulatory patients. Ultrasound guidance and stimulating catheters can help anesthetists during the procedure.

Atlas of Ultrasound- and Nerve Stimulation-guided Regional Anesthesia.

Mayo Clinic, Jacksonville, Florida. clendenen.steven@mayo.eduAtlas of Ultrasound- and Nerve Stimulation-guided Regional Anesthesia. By Ban C. H. Tsui, M.D. Consulting Editors: Vincent W. S. Chan, M.D., Brendan T. Finucane, M.B., B.Ch., Thomas Grau, M.D., Ph.D., and Anil H. Walji, M.D., Ph.D. New York, Springer Science+Business Media, 2007. Pages: 302. Price: $170.00.Regional anesthesia has made rapid advancement over the past 30 yr with the introduction of electrical stimulation to guide needle placement and the most recent addition of ultrasound. The key to a successful block is to deliver the local anesthetic to the target nerves. Atlas of Ultrasound- and Nerve Stimulation-guided Regional Anesthesia illustrates how to combine ultrasound and nerve stimulation to advance the art of regional anesthesia to a more scientific approach.The book’s first two chapters are brief introductions into the logistics of establishing a block room and garnering the supplies needed. They also include a comprehensive review of the physics of nerve stimulation and features of the equipment needed. The authors emphasize that nerve stimulation can be very helpful to novices as they learn to incorporate ultrasound into their regional practices, with the goal of confirmation that nerves on images and reactive to stimulation are actually nerves.Chapters 3 and 4 provide an elementary look at the ultrasound basics, including physics and workings of the ultrasound machine. These chapters provide guidance in choosing the correct ultrasound probe (linear vs. curved array), which is essential for obtaining adequate images that will identify nerves. Tissue sonoanatomy, required to identify the various structures within ultrasound images, is introduced. After identifying the nerve, one of the more difficult issues to learn is to track the needle to the target nerve. Practical tips are given to assist clinicians in observing and maintaining the trajectory of the needle. The author introduces a “training wheel” laser light attachment system that he has developed to aid the beginner in aligning the ultrasound beam with an in-plane technique in guiding the needle to the nerve.The remainder of the book is divided into chapters describing the most common regional blocks. The author is consistent with his stepwise approach to convey an easy and clear method in performing the various blocks with introduction of clinical anatomy followed by surface anatomy. Anatomical dissections, corresponding magnetic resonance imaging images, and ultrasound images are used for comparison to provide clinicians with a comprehensive view of anatomy. The message is clear that performing a successful regional block is dependent on a thorough understanding of anatomy. The chapters describe how to position the ultrasound probe to obtain the best images to perform the block. Comparison ultrasound scans of labeled and unlabeled images are educational tools used to learn the sonoanatomy of the different blocks. Appropriate motor responses to nerve stimulation are listed for each of the individual target nerves. Clinical pearls and troubleshooting suggestions are detailed at the end of each chapter.Chapter 16 explores the role of ultrasound with regional catheter placement and stimulating catheters. As the author notes, there is not an abundance of information in the literature regarding ultrasound guidance of catheters and stimulating versus nonstimulating catheters. The chapter is based primarily on the author’s clinical experience and gives several helpful suggestions on placement of catheters.One of the challenges of ultrasound imaging is learning sonoanatomy and being able to identify nerves. Examples of the ultrasound images throughout the book were adequate but challenging. In several of the images, it was difficult to clearly see the nerves, a problem that is unfortunately realistic and often the case when performing ultrasound-guided nerve blocks. For the beginner, it may be helpful to be able to compare both ideal and mediocre ultrasound images.In summary, the authors are to be congratulated for a well-designed book that explains their approach to performing regional blocks with the aid of nerve stimulation and ultrasound. The book offers an easy-to-follow stepwise introduction of ultrasound for beginners and several advanced ultrasound techniques for experienced clinicians. The book provides numerous practical suggestions on how to safely perform regional blocks with high success rates. This is an excellent resource for any clinician performing regional blocks.Mayo Clinic, Jacksonville, Florida.clendenen.steven@mayo.edu

Comparative evaluation of ultrasound‐guided continuous infraclavicular brachial plexus block with stimulating catheter and traditional technique: a prospective‐randomized trial

Secondary catheter failure has been reported in up to 40% of patients with continuous peripheral nerve blocks resulting in failure to provide pain relief after the initial block wears off. Introduction of stimulating catheters as well as ultrasound for regional anaesthesia has facilitated correct placement of catheter tip, closer to the plexus. This randomized study was conducted to compare the efficacy of continuous infraclavicular brachial plexus blocks using non-stimulating catheter, stimulating catheter and ultrasound-guided catheter placement with nerve stimulation assistance. Patients undergoing elective hand surgery were randomly allocated to receive continuous infraclavicular brachial plexus block using non-stimulating catheter [group traditional nerve stimulation (TR)], stimulating catheter [group stimulating catheter (ST)] or ultrasound-guided catheter placement with nerve stimulation assistance [group ultrasound guidance with nerve stimulation assistance (US)]. Motor and sensory blocks were assessed every 5 min and primary block success was determined at 30 min. After resolution of the primary block, threshold stimulating current and resulting response, spread of drug on re-injection as seen ultrasonographically and the capacity to re-establish block was documented. Complications and need for supplement was noted. The primary block success was significantly higher in the US group [96% US, 58% ST, 59% TR (P=0.0005)]. Secondary catheter failure was significantly lower in the US group [9% US, 17% ST, 86% TR (P<0.0001)]. Axillary nerve was blocked more predictably in the US group (100% US, 79% ST, 50% TR (P=0.0003). In this study, ultrasound guidance with nerve stimulation assistance significantly improved primary success and reduced secondary catheter failure in continuous infraclavicular brachial plexus blocks.

Stimulating Catheters for Continuous Femoral Nerve Blockade After Total Knee Arthroplasty: A Randomized, Controlled, Double-Blinded Trial

Continuous femoral nerve blockade (CFNB) is often used for postoperative analgesia after total knee arthroplasty (TKA). CFNB can be instituted using a variety of techniques. Stimulating catheters (SC) have the advantage of confirming placement of the catheter close to the nerve during advancement. In this randomized, controlled, double-blind trial, we compared a SC with a nonstimulating catheter (NSC) technique for institution of CFNB and its effects on quality of analgesia after TKA performed under general anesthesia in 82 patients. Patients were randomized to have CFNB instituted using either a NSC or a SC technique. Sensory blockade was assessed 10 and 20 min after injection of lidocaine via femoral catheter and on postoperative days 1 (POD 1) and 2 (POD 2). A standardized multimodal analgesic technique, including a single injection sciatic block (preoperative), i.v. morphine (patient-controlled analgesia), celecoxib, and paracetamol, was administered to all patients. Outcome variables included morphine requirements, pain scores, and markers of early recovery. The proportion of patients with sensory blockade in the femoral nerve distribution was between 90% and 95% at all measurement times with no difference between groups. In the first 24 h, the NSC group required 19.5 (1-67) [median (10th-90th centiles)] mg morphine compared with the SC Group 18 (2-51) mg (P = 0.69). At 24 h, the 95% confidence interval for difference in morphine consumption between groups was -8 to 5 mg. There was no difference between groups in visual analog scale scores at rest on POD 1 and POD 2, during active and passive physiotherapy; and in markers of early recovery after surgery. In this study, blind catheter advancement was as reliable as a SC technique for establishing and maintaining CFNB for postoperative analgesia as a part of multimodal analgesia technique after TKA.

Stimulating Catheter as a Tool to Evaluate Peripheral Nerve Function During Hip Rotationplasty

Stimulating catheters have been introduced into clinical practice to confirm perineural localization of the catheters. The muscular twitch induced over the catheter may be used to evaluate nerve function intraoperatively. Therefore, the function of the sciatic nerve was evaluated during major cancer surgery of the femur. A 7-year-old boy (29 kg) was scheduled for hip rotationplasty for resection of an osteosarcoma of the left femur under general anesthesia and postoperative pain therapy with an epidural stimulating catheter. In hip rotationplasty the femur is resected, the lower limb and foot are rotated 180 degrees and the tibia plateau is attached to the pelvic acetabulum to form a new hip joint. During preparation of the left thigh and the sciatic nerve, motor responses to stimulation of the catheter were preserved, but the stimulation threshold increased. After vascular anastomosis the foot remained cold, therefore ropivacaine was applied epidurally and subsequently a warming of the foot was observed. At the end of the operation, the patient was free of pain, a good capillary pulse of the leg was observed, and the patient was able to move the foot and toes of the rotated leg. The use of epidural stimulating catheters as a tool to monitor nerve function is a novel and simple procedure to monitor nerve function intraoperatively and to enable good postoperative pain control.

Equipment for regional anesthesia in children

Pediatric pain management has started to advance over the past few decades, perhaps due to both increased recognition of suboptimal pain control in children and introduction of various advanced techniques and sophisticated equipment promising to improve accuracy with placement of needles and catheters. This chapter discusses equipment used in pediatric anesthesia and analgesia today with special emphasis on equipment used for nerve stimulation and ultrasound guidance during peripheral and central anesthesia and analgesia. Although caudal blocks remain popular for pediatric analgesia, single-shot and continuous peripheral nerve blocks will become more common due to the advances with stimulating catheters and ability to visibly monitor the procedures under ultrasound guidance. Electrical epidural (nerve root) stimulation shows great promise to increase reliability, and potentially safety, when introducing and advancing of catheters within the epidural space. Ultrasonographic guidance during peripheral and central nerve blockade is suitable for children, particularly as their nerve structures are more superficial than adults and the image resolution is greater. The ability to use ultrasound to avoid puncturing vital structures as well as to reduce local anesthetic requirements are both very beneficial in this population. Bringing high technology imaging into operating rooms is a giant leap for regional anesthesia.