Needle Entry Research Articles

Do the Gaps in the Ligamentum Flavum in the Cervical Spine Translate into Dural Punctures? An Analysis of 4,396 Fluoroscopic Interlaminar Epidural Injections

Background: Cervical interlaminar epidural injections are performed frequently in managing chronic neck and upper extremity pain, although less commonly than lumbar interlaminar epidural injections. Recently, the US Food and Drug Administration warnings and safeguards to prevent neurologic complications. These were developed by the Multi-Society Pain Workgroup have taken center stage for all types of epidural injections, including cervical interlaminar epidural injections. The recommendations of safeguards to prevent neurologic complications after epidural steroid injections include that cervical interlaminar epidural injections must be performed utilizing fluoroscopy with anteroposterior, lateral, or oblique views with injection of contrast medium and that entry be limited to the C7-T1 epidural space or occasionally the C6-C7 with requirements for magnetic resonance imaging assessment of the epidural space. Objectives: To assess the incidence of dural puncture associated with fluoroscopically directed cervical interlaminar epidural injections. Study Design: A retrospective assessment of patients undergoing cervical interlaminar epidural injections from January 2012 through February 2015. Setting: A private interventional pain management practice; a specialty referral center in the United States. Methods: The data were collected for 4,396 consecutive cervical interlaminar epidural injections performed from January 2012 through February 2015. The procedures were all performed under fluoroscopic visualization under posteroanterior view with contrast medium injection with lateral view confirmation when indicated. The procedures were performed by one of 2 physicians; the dural puncture and subsequent postoperative complications with level of epidural entry were determined. Outcomes Assessment: The outcome was assessment of dural puncture. Results: A review of multiple manuscripts showed that defects in the ligamentum flavum may extend to as much as 100% of the population. However, it also has been shown that among the levels with a gap, the location of a gap in the caudal third of the ligamentum flavum was more frequent than in the middle or cephalic portion of the ligamentum flavum. Among the 4,396 epidural injections performed at C7-T1, C6-C7, and C5-C6, 1,227 were performed at C7-T1; 1,835 were performed at C6-C7; and 1,334 were performed at C5-C6. Dural punctures were observed in 1.8% (24 procedures) at the C5-C6 level entry; 0.87% (16 procedures) at the C6-C7 level entry; and 1.71% (21 procedures) at the C7-T1 level. There was no significant difference among the entry levels. No complications or spinal cord damage or postdural puncture headache were observed. Limitations: The limitations of this report include that it is an assessment by only 2 well experienced physicians, even though it included a relatively large number of patients Conclusion: This study illustrates that dural puncture is equally prevalent, though very rare, irrespective of the needle entry level into the epidural space, with an overall dural puncture rate of 1.4%, with 1.8% at the C5-C6 level, 0.87% at the C6-C7 level, and 1.71% at the C7-T1 level. Based on the present literature, it appears that performing the procedure by inserting the needle into the cephalic portion of the intervertebral space rather than the caudal portion may be safer. Key words: Cervical interlaminar epidural injection, dural puncture, steroids, neck pain, upper extremity pain.

Tracking Anatomical Variation of the Bifurcation of the Radial Nerve: Clinical Implication for Physicians

Regional nerve blocks of the upper limb are usually performed in the brachial plexus, specifically in the supra- or infra-clavicular or axillary nerve regions, in cases where minor surgical procedures are required in the distal portion of the extremity. These approaches may not be optimal due to the close proximity of major vascular structures to the needle entry site. This quantitative study measured the site of the radial nerve bifurcation using calipers and ultrasound (US) to determine whether minor surgical procedures (i.e., wound exploration, laceration repair and distal radius reduction) could rely on nerve blocks within a single nerve distribution, in a defined region of the cubital fossa. A metal cylinder was aligned along the medial and lateral epicondyles of 59 donor body arms. A digital caliper, perpendicular to the cylinder, allowed for measurement above (+) or below (-) the epicondylar line (0mm). The average bifurcation occurred at -13.84mm, with 85% of bifurcations arising in the forearm below 0mm. US digital data from a cross-sectional sample of live patients were included in our analysis. US guided needle nerve blocks are presently used by physicians for cases involving injury distal to the elbow. Our results indicate that it is possible to establish “safe zone” parameters in regional nerve blocks to maximize functional recovery while minimizing collateral vascular damage.

V10-05 ROBOT ASSISTED BLADDER AUGMENTATION AND BILATERAL URETERAL REIMPLANTATION

INTRODUCTION AND OBJECTIVES: Despite use of barbed suture during robot-assisted radical prostatectomy or partial nephrectomy, concerns have been raised about a high early failure rate when used during minimally-invasive pyeloplasty (MIP). In this video, we present our technique of robotic pyeloplasty using barbed suture, review the literature on barbed suture for MIP and discuss the controversies, tips, and tricks. METHODS: We present a case of a 55 year old man with rightsided uretero-pelvic junction obstruction (UPJO). The patient was placed in the modified flank position. Port placement was a 12 mm camera port, two 8 mm robotic ports, and a 5 mm assistant port. The robot was docked at a 30-degree angle to the flank. A robotic cautery hook was used to aid with fine hemostatic dissection. The renal pelvis and upper ureter were mobilized to reveal a crossing vessel. Round tip scissors were used to perform dismemberment and spatulation (Anderson-Hynes technique). The ureter was transposed over the crossing vessel and anastomosis was performed using a unidirectional barbed suture (3-0 Stratafix ; Ethicon, Somerville, NJ, USA) in a running fashion. Following completion of the posterior layer, an antegrade ureteral stent was placed followed by closing the anterior layer in a similar fashion. RESULTS: Strategies for successful robotic pyeloplasty using barbed suture include: (1) selection of appropriate barbed suture e suture composition, absorbability, distribution of barbs and needle type vary between manufacturers (2) minimizing tension during suture placement to avoid tissue necrosis (3) use of round tip scissors to avoid spiral spatulation of the ureter (4) use of the obstructing UPJ tissue as a handle-hold for manipulation (5) avoid use of 12 mm assistant port for needle entry by utilizing needle placement via a robotic port. Advantages of barbed suture include no loss of tension as seen in non-barbed monofilament suture with possibility of suture loosening, and use of a “continuous interrupted” method; the barbs allow the anastomotic tension to be evenly spread to avoid gaps and mimic interrupted suture. Of 18 patients who have undergone laparoscopic or robotic pyeloplasty using barbed suture at our institution, the success rate was 17/ 18 (94%). CONCLUSIONS: Barbed suture for MIP provides a watertight anastomosis that is technically easier to perform. A key principle is to know your barbed suture as incorrect suture selection may compromise success. Our results demonstrate excellent success rates when using the barbed suture for MIP.

Lateral Sagittal Infraclavicular Block Under Sedation in a Four-Year-Old Child.

To the Editor, The advantages of a lateral sagittal infraclavicular block (LSIB) include easily identifiable landmarks, the ability to determine the needle entry site and a minimal risk of pneumothorax, as described by Klaastad et al. (1) using magnetic resonance imaging (MRI) in adults. However, there are few studies and cases concerning the use of LSIB under sedation or general anaesthesia (2–4). In a letter including four paediatric cases, 15–20 mL of bupivacaine 0.25% with epinephrine (1:200,000) was used, and in a study with 80 children, 0.5 mL kg−1 of bupivacaine 0.25% with adrenaline (5 μg mL−1) was used for LSIB under general anaesthesia (2, 3). In another study, 0.5 mL kg−1 of ropivacaine 0.5% was used for the lateral vertical infraclavicular block, under sedation, in children (4). Here, we report the case of a 4-year-old male child (height 110 cm, weight 20 kg, ASA I) who received LSIB under sedation for left trigger thumb surgery. EMLA® cream (Astra Zeneca, Wedel, Germany) was applied to the right hand for venous cannulation, in which a 22 G venous cannula was inserted, and 0.05 mg kg−1 of midazolam and 0.5 mg kg−1 of ketamine were administered intravenously for sedation. In the operating room, standard monitoring (electrocardiogram, non-invasive blood pressure, pulse oximetry) was applied. The level of sedation was assessed using the Ramsey Sedation Scale, and while the sedation score (SS) was 2, the block was performed with the patient in the supine position and head turned to his right side. With the anaesthesiologist standing behind the child’s left shoulder, the arm was adducted, and the left hand was placed on the abdomen. Although the point of the needle insertion is stated as the intersection between the clavicle and the coracoid process (CP) in the literature (1–3), we inserted the needle 1 cm inferiorly to the intersection between the clavicle and the CP (Figure 1). Figure 1 Left infraclavicular region illustrating the lateral sagittal infraclavicular block using the inferior approach. The needle is placed at the 1 cm inferiorly to the intersection between the clavicle and the CP After antiseptic preparation of the area, 1 mL of lidocaine 1% was infiltrated. A 22 G, 50-mm, insulated needle (Stimuplex A; B. Braun Medical Ltd., Melsungen, Germany) was connected to the active lead of the nerve stimulator (Stimuplex HNS 11; B. Braun Medical Ltd., Melsungen, Germany), and 1.5-mA current impulses of 0.1 ms in duration at a frequency of 1 Hz were delivered. The needle was inserted caudally in a sagittal plane and 60° from the skin on a horizontal plane. At a depth of 10 mm, flexion of the thumb, second and third fingers was accepted as a median nerve response, elicited with a current of 0.3 mA but not with 0.2 mA. Slowly, 5 mL of a bupivacaine 0.25% and lidocaine 1% mixture was injected. During needle insertion and redirection, continuous aspiration was performed to detect any possible intravascular placement. Twenty minutes after the block was completed, the patient was tested by the surgeon before incision, and pain-free surgery was begun. During the surgery, the patient was cooperative (SS=1) and required no additional sedation. The surgical procedure lasted 30 minutes. The duration of motor block and sensory block were approximately 2.5 and 6 hours, respectively. Throughout the anaesthesia, there was no change in haemodynamic parameters. Additionally, there were no intra- or postoperative complications. We conclude that LSIB using the inferior approach with lowdose local anaesthetics (0.25 mL kg−1) under sedation may be an option for regional and general anaesthesia in minor hand, forearm and elbow surgery in children. However, the limitation of block performance under sedation in children is the risk of sudden, unexpected movements, which may be higher in children than in adults.

A simple technique to improve the administration of nerve root blocks.

Nerve root injections require radiographic imaging and good technical skill. We describe a simple method to aid planning the administration of lumbar nerve root injections with the use of biplanar fluoroscopy. Axial magnetic resonance imaging at the level of the target nerve root is used. An empirical angle of inclination of 60° is created from the nerve root to the skin of the back with the apex enabling the lateral entry point to be determined (Fig 1). The transforaminal injections are then performed with the simple expedient of a skin marker line at the appropriate lateral distance from the midline for needle entry. Figure 1 Method to aid planning the administration of lumbar nerve root injections

Treatment of vertebral body compression fractures using percutaneous kyphoplasty guided by a combination of computed tomography and C-arm fluoroscopy with finger-touch guidance to determine the needle entry point.

This study aimed to evaluate the results and complications of image-guided percutaneous kyphoplasty (PKP) using computed tomography (CT) and C-arm fluoroscopy, with finger-touch guidance to determine the needle entry point. Of the 86 patients (106 PKP) examined, 56 were treated for osteoporotic vertebral compression fractures and 30 for vertebral tumors. All patients underwent image-guided treatment using CT and conventional fluoroscopy, with finger-touch identification of a puncture point within a small incision (1.5 to 2 cm). Partial or complete pain relief was achieved in 98% of patients within 24 h of treatment. Moreover, a significant improvement in functional mobility and reduction in analgesic use was observed. CT allowed the detection of cement leakage in 20.7% of the interventions. No bone cement leakages with neurologic symptoms were noted. All work channels were made only once, and bone cement was distributed near the center of the vertebral body. Our study confirms the efficacy of PKP treatment in osteoporotic and oncological patients. The combination of CT and C-arm fluoroscopy with finger-touch guidance reduces the risk of complications compared with conventional fluoroscopy alone, facilitates the detection of minor cement leakage, improves the operative procedure, and results in a favorable bone cement distribution.

The use of electrical stimulation to guide epidural and intrathecal needle advancement at the L5-L6 intervertebral space in dogs

ObjectiveTo determine the minimal electrical threshold (MET) necessary to elicit appropriate muscle contraction when the tip of an insulated needle is positioned epidurally or intrathecally at the L5-6 intervertebral space (phase-I) and to determine whether the application of a fixed electrical current during its advancement could indicate needle entry into the intrathecal space (phase-II) in dogs. Study designProspective, blinded study. AnimalsThirteen (phase-I) and seventeen (phase-II) dogs, scheduled for a surgical procedure where L5-6 intrathecal administration was indicated. MethodsUnder general anesthesia, an insulated needle was first inserted into the L5-6 epidural space and secondly into the intrathecal space and the MET necessary to obtain a muscular contraction of the pelvic limb or tail at each site was determined (phase-I). Under similar conditions, in dogs of phase-II an insulated needle was inserted through the L5-6 intervertebral space guided by the use of a fixed electrical current (0.8 mA) until muscular contraction of the pelvic limb or tail was obtained. Intrathecal needle placement was confirmed by either free flow of cerebrospinal fluid (CSF) or myelography. ResultsThe current required to elicit a motor response was significantly lower (p < 0.0001) when the tip of the needle was in the intrathecal space (0.48 ± 0.10 mA) than when it was located epidurally (2.56 ± 0.57). The use of a fixed electrical stimulation current of 0.8 mA resulted in correct prediction of intrathecal injection, corroborated by either free flow of CSF (n = 12) or iohexol distribution pattern (n = 5), in 100% of the cases. Conclusion and clinical relevanceNerve stimulation may be employed as a tool to distinguish epidural from intrathecal insulated needle position at the L5-6 intervertebral space in dogs. This study demonstrates the feasibility of using an electrical stimulation test to confirm intrathecal needle position in dogs.

POSITIVE ASPIRATION AND ITS SIGNIFICANCE DURING INFERIOR ALVEOLAR NERVE BLOCK - A PROSPECTIVE STUDY

Abstract Background and aims: It is a basic rule to aspirate before injection when giving an inferior alveolar nerve block because the local anaesthetic may fail if the injection is given into a blood vessel, and the local anaesthetic solution may have undesirable systemic effects. There are reports that indicate aspiration is not performed in every injection. The aim of the present study was to assess the incidence of intravascular needle entrance in inferior alveolar nerve block injections. Patients and methods: Interns and postgraduates of our institute performed inferior alveolar nerve block injections using conventional technique in 250 patients undergoing minor oral surgical procedures. The results of aspiration were reported. Aspirable syringes and 27 gauge long needles were used, and the method of aspiration was similar in all cases.Data were analyzed using t-test. Results: 20% of inferior alveolar nerve block injections were aspiration positive. Of all injections, 15.8% were intravascular on the right side and 14.8% were intravascular on the left. There were no statistically significant differences between right and left injection sites (P = 0.778). Between the ages of 9 and 19 the incidence of intravascular penetration was significantly greater than at other ages (10/28 compared with 39/222, P = 0.04). Conclusion: Aspiration of the syringe after the needle had been placed in position for an inferior alveolar nerve block (but before the anaesthetic solution was injected) in 250 patients showed that the tip of the needle was in a blood vessel in 49 (20%). Aspiration of blood was significantly more common in patients aged 9–19 years than in all others (P=0.04). It seems that side of injection has no considerable effect in incidence of intravascular needle entrance.

Lumbar plexus block for management of hip surgeries.

Background:Lumbar plexus block (LPB) is one of the anesthetic options in the elderly patients undergoing hip surgeries. LPB could be safe because it targets somatic nerve in psoas region. Effectiveness of LPB is attributed to the sufficient analgesia provided intraoperatively as well as postoperatively. Adequate muscle relaxation and immobility during surgery refers to its acceptability.Objectives:In this study, LPB was used as the anesthetic method to manage the elderly patients subjected to hip surgery.Patients and Methods:A total of 50 patients aged 51 to 100 years were enrolled in this study. LPB was accomplished after a mild sedation and with a modified method using patient's fingertip width (FTW) as the distance unit to determine needle entry point under electrical nerve stimulation assistance. After targeted injection, procedure time, establishment time, block duration, surgery time, hemodynamic variables, and surgeon satisfaction score were documented and analyzed. Propofol in trivial doses was infused intraoperatively to provide clinical sedation.Results:Mean patient's age was 73 ± 12 years with ASA II/III. Procedure time was 5.65 ± 1.24 minutes, establishment time was 130 ± 36 seconds, block duration was 13.1 ± 8 hours, surgery time was 149.7 ± 32.2 minutes, and surgeon satisfaction score was 9.8 ± 0.1. There was no complication and no failure. Hemodynamic stability was pleasantly achieved.Conclusions:By preserving hemodynamic stability, LPB in conjunction with a light sedation could be considered as a reliable prudent satisfying anesthetic option in management of hip fractures in the elderly patients with three beneficial characteristics of safety, effectiveness, and acceptability.

Individual differences in field independence influence the ability to determine accurate needle angles

"Field dependence" is used in cognitive psychology to describe an individual's tendency to be visually distracted by the surrounding environment. Notwithstanding the role of field dependence in contexts in which spatial judgment is important, such as piloting an aircraft, to date, studies linking field dependence to surgical skills have been limited. We evaluated whether field dependence correlates with an ability to anticipate appropriate needle angles in a simulated setting. Trainees underwent field dependence testing and then participated in a surgical skills exercise. Correlations between field dependence and surgical skill were computed. Specifically, cardiothoracic surgery residents (n=11) took a battery of cognitive examinations to assess general reasoning and visuospatial judgment. Two written tests, the Rod and Frame test and the Judgment of Line Orientation test, measured the degree of field dependence. The subjects then underwent surgical skills testing. Using a standard needle driver, the participants placed curved needles into a cylindrical silicone mitral valve model with 10 premarked needle entry and exit sites. The components assessed included the ability to load a needle on driver at the appropriate angle. The test results showed a parametric distribution, with internal cognitive testing controls demonstrating valid testing techniques and methods. Performance on the cognitive tests measuring spatial judgment and field dependence correlated significantly with skill at determining the appropriate needle angle load in an inverse fashion (Judgment of Line Orientation test, r=0.61, P<.05; Rod and Frame test, r=-0.52, P=.05), suggesting that residents who were not distracted by surrounding objects performed better. Performance on the cognitive examinations did not correlate with resident training level. Although our study was of a small cohort, the findings suggest that individuals described as field independent (not easily distracted by external visual cues) might possess improved ability to determine appropriate needle angle loads compared with field-dependent individuals. Additional studies examining the role field dependence might play in the acquisition and execution of surgical tasks are warranted.

PD37-09 THE LASER-DARRT: A NOVEL DIRECT ALIGNMENT REDUCED RADIATION TECHNIQUE FOR PERCUTANEOUS RENAL ACCESS

INTRODUCTION AND OBJECTIVES: The traditional bullseye technique for obtaining renal access in percutaneous nephrolithotomy (PCNL) utilizes continuous fluoroscopy and accounts for substantial radiation exposure. In an attempt to minimize the radiation dose, we describe a novel laser-DARRT (Direct Alignment Reduced Radiation Technique) using direct alignment of the percutaneous access needle with the laser beam from the fluoroscopic C-arm system. METHODS: In the laser-DARRT technique, fluoroscopy was used to select the needle entry site above the calyx of interest. The Carm was positioned with the laser beam on the skin over the desired access site at a 30 degree angle. The access needle was placed such that the needle tip and hub were both aligned with the laser beam. The needle was inserted into the renal calyx using tactile feedback while maintaining alignment with the laser. Needle depth and successful calyceal puncture were confirmed both fluoroscopically and under direct vision. A randomized-controlled study was performed using a benchtop kidney model. Twenty medical personnel were tested using both the bullseye and laser-DARRT techniques and the results were stratified by subject experience level. Each subject obtained needle access to the upper, middle, and lower pole of the kidney model using both techniques. The primary endpoint was total fluoroscopy time. Secondary endpoints included insertion time, number of puncture attempts, number of course corrections, and subjective procedural difficulty. Paired samples Wilcoxon signed rank tests were used for statistical analysis with significance at p<0.05. RESULTS: A total of 120 needle placements were recorded by the 20 study subjects (60 conventional and 60 Laser DARRT). The fluoroscopy time required to obtain needle access using the LaserDARRT technique was significantly reduced compared to the conventional technique in all groups, including the attendings/fellows (7.09 vs. 18.51 sec; p<0.001), residents (6.55 vs. 13.93 sec; p1⁄40.001), and medical students (6.69 vs. 20.22 sec; p<0.001). The medical students also rated the Laser DARRT technique easier to use (2.56 vs. 4.89; p<0.001). No difference was seen in total access time, puncture attempts, or course corrections between techniques. CONCLUSIONS: The laser-DARRT for percutaneous renal access reduced fluoroscopy time by 63% compared with a conventional bullseye technique. The least experienced users found the laserDARRT significantly easier to learn. This is a promising new technique that merits additional testing in animal and human models.

Three dimensional MRI study: Safety of short versus long needle peribulbar anesthesia

BackgroundThe standard technique of Peribulbar block is to use 25g 25mm needle at the junction between the lateral one third and medial two third of the lower orbital rim in the infero-temporal quadrant of the orbit. Theoretically, insertion of longer needles increases the potential of injury to important structure; however, safety of the shorter needle had never been demonstrated. This study describes the anatomy of the orbital structures with magnetic resonance imaging (MRI) using the three-dimensional constructive interference in steady state (3D CISS) sequence to present a morphological basis for needle entry at 12.5 and 25mm lengths. Statistical comparisons were performed at the 12.5 versus 25mm depths. Statistical significance was indicated by P<0.05. MethodFifty patients free of orbital pathology with normal axial length were selected for MRI with the 3D CISS sequence. Original axial and multiplanar image reconstruction (MPR) images were selected for image interpretation. Orbital structures were identified at 12.5 and 25mm depths from the orbital rim to compare significant differences in anatomy between the two imaging planes at the expected needle depth and to assess the size of the globe and the orbit. ResultsThe cross sectional area of the extraocular muscles were statistically significantly smaller at the 12.5mm plane (P=0.001). The area of inferotemporal fat was statistically significantly larger at the 12.5mm plane (P=0.033). There was no statistical difference in the inferonasal and superonasal fat areas at different depths (P=0.34, P=0.35 respectively). The size of the orbit and globe was significantly larger at 12.5mm (P=0.001). There was no difference between depths in the presence or absence of neurovascular bundles and supporting structures including the intramuscular septae. ConclusionThere is a larger structure-free space at a depth of 12.5mm than at 25mm. Therefore, the inference is that a needle inserted in the infero-temporal zone to a depth of 12.5mm is less likely to injure the eyeball or extra-ocular muscles than one advanced to 25mm.

Optimal Needle Entry Angle for Cervical Transforaminal Epidural Injections

Background: Cervical epidural steroid injections can be performed through either interlaminar or transforaminal approaches, although the interlaminar approach is more frequently used, for cervical radicular pain as a result of cervical disc herniation or spinal stenosis. Cervical selective nerve root block (CSNRB) is an injection that uses a similar approach to that of cervical transforaminal epidural steroid injection (CTFESI) but CSNRB is mainly used for diagnostic injection, often with local anesthetic only. Objective: The aim of this study was to investigate an optimal needle entry angle for cervical transforaminal epidural steroid injection (CTFESI) or cervical selective nerve root block (CSNRB) using the fluoroscopically guided anterior oblique approach. The angle for optimal entry into the neuroforamen was measured at various vertebral levels using cross-sectional cervical spine computed tomography (CT) scans. Study Design: Retrospective case series analysis. Methods: From March 2009 to July 2012, consecutive patients with presumed discogenic neck pain underwent cervical post discography CT scans. The axial images of these CT scans were used to measure the optimal angle for needle entry into the neuroforamen. The angles were taken bilaterally at levels of C3-4, C4-5, C5-6, C6-7, and C7-T1. The average angle between the patient’s left and right side was calculated. A total of 190 patients were analyzed, including 73 men and 117 women, with ages ranging from 21 to 78 years old. Results: In both men and women, the mean optimal angle (in degrees) with standard deviation measured in the 190 patients at C3-4, C4-5, C5-6, C6-7, and C7-T1 were 48 ± 4, 49 ± 4, 49 ± 4, 49 ± 5, 48 ± 6, respectively. The 95% confidence interval for the true value of the parameter is within 39.84 to 57.56 degrees. Limitations: The data for the optimal needle entry angle for CTFESI has yet to be tested or confirmed in clinical studies. Conclusion: This is the first study investigating the optimal needle entry angle for performing CTFESIs or CSNRB. Based on a patient population of 190, the optimal entry angle using the anterior oblique approach appears to be between the range of 33 to 68 degrees with an average of slightly less than 50 degrees. Further research with angle of needle entry and/or initial fluoroscopic alignment of approximately 50 degrees in CTFESI or CSNRB is warranted to confirm the usefulness of these findings. Key words: Pain medicine, transforaminal, cervical, epidural, cervical selective nerve root block, cervical disc herniation, interlaminar, neck pain, vertebral artery, radiculomedullary artery

Using XperGuide Planning Software to Safely Guide Catheter Access to the Cavernous Sinus via Transorbital Puncture

Many techniques for accessing the cavernous sinus have been described, from a transfemoral venous approach to a direct surgical exposure and cannulation of the superior ophthalmic vein. The cavernous sinus can be accessed safely through direct transorbital puncture and cannulation of a preceding venous confluence with an 18-gauge angiocatheter. This technique is performed under constant fluoroscopy using bony landmarks. The use of XperGuide software allows the operator to obtain an intraprocedural computed tomography and to identify the optimum needle entry point and trajectory to avoid at-risk structures such as the optic nerve in this case. This trajectory is then superimposed onto the real-time fluoroscopic image, and the guidance trajectory is followed during needle insertion. The patient is a 66-year-old woman who spontaneously developed a left-sided cavernous sinus syndrome. She was found to have an indirect carotid cavernous fistula on angiography. Because of tortuosity and occlusion of venous access points to the cavernous sinus, access via transorbital puncture was preferred. The XperGuide system was used to avoid the at-risk structures, and coils were safely deployed within the cavernous sinus after successful cannulation with this guidance system. The patient had complete resolution of her fistula and experienced no complications from the procedure. The XperGuide software guidance system is helpful during direct transorbital puncture of the cavernous sinus because it allows better monitoring of real-time needle location along a safe trajectory selected by the operator to avoid damaging local soft tissue structures.

Keys to minimizing the risk of spinal cord trauma during a lumbar approach to thoracic epidural

Thoracic epidurals provide effective analgesia for thoracic or upper abdominal procedures for both adult and pediatric patients; however, using a thoracic approach to place an epidural catheter is not without risk as it requires needle placement immediately posterior to the spinal cord. Consequently, some clinicians prefer to use a lumbar approach (caudal approach in pediatric cases), or if unsuccessful at a thoracic level, they may thread the epidural catheter cephalad from that point. This issue of the Journal features an interesting study by Gamble et al. in which the authors used a porcine model to address the safety of threading an epidural catheter via a lumbar approach. In their study, the authors show that styletted stimulating thoracic epidural catheters can be advanced in a predictable manner to target thoracic myotomes using a lumbar approach. However, damage to the spinal cord was observed in several animals. It is important to point out that, in humans, such perturbing findings are probably limited to high lumbar approaches (i.e., above L2-L3). This is partly because the human adult spinal cord, unlike the porcine model used in the Gamble et al. study, typically ends at approximately the L1-L2 level. Thus, if needle entry occurs either at or below the L2-L3 level, the risk of direct blunt trauma caused by the initial threading of the catheter from the needle tip is minimized. Nevertheless, the results of Gamble et al.’s study clearly show the risks involved when a catheter is advanced directly towards the spinal cord, as in thoracic and high lumbar approaches. Several key factors influence the risk and potential for spinal cord damage during these approaches, including the angle of catheter insertion, catheter stiffness, and applied force. To address this issue, the relationship between these three factors must be considered. Force must be applied to advance the catheter to its desired target myotome level. This threading force is the total applied force needed to insert the catheter through the Tuohy needle into the epidural space. Threading force itself involves two component forces that must be considered during catheter insertion: a bending force, needed to advance the catheter out of the needle, and a parallel force, needed to thread the catheter cranially past any obstacle within the epidural space (Fig. 1). Assuming there is minimal obstruction along the spinal cord, the initial total threading force is then directly related to the bending force. This is shown in Gamble et al.’s experiment where, in most animals, difficulty was experienced in advancing the catheter beyond the needle tip. The perpendicular angle of insertion used by the authors suggests the need for considerable bending force to advance the catheter out of the needle. Furthermore, the authors speculate that catheter stiffness and the presence of the stylet added to the difficulties in initial catheter advancement. Thus, the bending force required to advance the catheter out of the needle is influenced by two key factors: angulation of the needle and catheter stiffness (i.e., styletted or not). To show this relationship, we used a simple in vitro setup to demonstrate the peak (kilogram) force generated when threading a styletted catheter at various needle angles (Figure). As shown, the peak force increases dramatically as the angulation of the needle approaches 0 (i.e., perpendicular) relative to the surface of the force gauge transducer. With an insertion perpendicular to the plane of the back (i.e., no angulation), these results suggest that the B. C. H. Tsui, MD (&) Department of Anesthesiology and Pain Medicine, University of Alberta, 8-120 Clinical Sciences Building, Edmonton, AB T6G 2G3, Canada e-mail: btsui@ualberta.ca

Evaluation of the Impact of Three-Dimensional Vision on Laparoscopic Performance

Recent technological advancements have led to the introduction of new three-dimensional (3D) cameras in laparoscopic surgery. The 3D view has been touted as useful during robotic surgery, however, there has been limited investigation into the utility of 3D in laparoscopy. We performed a prospective, randomized crossover trial comparing a 0° 3D camera with a conventional 0° two-dimensional (2D) camera using a high definition monitor (Karl Storz, Tuttlingen, Germany). All participants completed six standardized basic skills tasks. Quality testing scores were measured by the number of drops, grasping attempts, and precision of needle entry and exiting. Additionally, resolution, color distribution, depth of field and distortion were measured using optical test targets. In this pilot study, we evaluated 10 medical students, 7 residents, and 7 expert surgeons. There was a significant difference in the performance in all the six skill tasks, for the three levels of surgical expertise and training levels in 2D vs 3D except for the cut the line quality score and the peg transfer quality score. Adjusting for the training level, 3D camera image results were superior for the number of rings left (p=0.041), ring transfer quality score (p=0.046), thread the rings (no. of rings) (p=0.0004), and thread the rings quality score (p=0.0002). The 3D camera image was also superior for knot tying (quality score) (p=0.004), peg transfer (time in seconds) (p=0.047), peg transfer pegs left (p=0.012), and for peg transfer quality score (p=0.001). The 3D camera system showed significantly less distortion (p=0.0008), a higher depth of field (p=0.0004) compared with the 2D camera system. 3D laparoscopic camera equipment results in a significant improvement in depth perception, spatial location, and precision of surgical performance compared with the conventional 2D camera equipment. With this improved quality of vision, even expert laparoscopic surgeons may benefit from 3D imaging.

Lateralizing Epidural Catheter Placement as Evidenced by Electrical Stimulation

Epidural steroids are more effective if administered in the anterolateral epidural space. It follows that the ability to administer local anesthetics in the ipsilateral anterolateral epidural space should likewise improve their efficacy for postoperative epidural analgesia. We determined whether epidural catheters can be reliably placed in the ipsilateral anterolateral epidural space using the paramedian approach. Motor responses elicited by electrical stimulation were used to identify lateralization. We further assessed what angle of needle insertion resulted in successful catheter placement. Epidural anesthesia was performed in 68 patients undergoing total joint arthroplasty using the paramedian approach. FDA-approved electrical stimulating catheters were utilized, and the muscle response elicited was recorded with each centimeter of advancement of the catheter. Digital photographs were taken to determine the angle of needle entry. Using the paramedian approach, an ipsilateral twitch was noted in 66 of the 68 patients (two had no response). With advancement of the catheter (2-5 cm), the twitch remained ipsilateral in 56 but disappeared in 12. The mean angle of the epidural needle was 40° to the midline. All patients had successful epidural anesthesia as evidenced by no response to surgical incision. Epidural catheters can be reliably placed onto the side of surgery using the paramedian approach. This provides the opportunity to more selectively administer epidural local anesthetics. Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Trajectory avoiding kidney and ureter injury for percutaneous lumbar sympathetic block.

Trajectory avoiding kidney and ureter injury for percutaneous lumbar sympathetic block.

The Vanishing Target Sign: Confirmation of Intraluminal Needle Position for Ultrasound Guided Vascular Access

Ultrasound-guided peripheral intravenous (USG-PIV) catheter placement has been described in the emergency medicine literature for more than a decade.1 Several studies have shown that USG-PIV placement can decrease the number of needle insertion attempts, decrease the number of potentially unnecessary central line placements, and increase patient satisfaction scores.1-5 Additional evidence has shown that this skill is accessible to ED staff other than physicians.6, 7 However, a randomized study of USG-PIV placement by emergency physicians with variable levels of experience did not demonstrate improved success rates, decreased time to insertion, or increased patient satisfaction.8 In our experience, consistent success with USG-PIV placement in patients with difficult access using a dynamic one-person technique is a challenging procedure. In an attempt to help teach this effectively, we have developed a method that employs a sign we call the “vanishing target” to ensure intraluminal positioning of the catheter needle tip. When ultrasound is used to guide needle placement into a vessel, two traditional approaches are employed: a short-axis, or out-of-plane, approach, and long-axis, or in-plane, approach. The long axis in-plane technique has the advantage of visualizing the needle shaft and tip, but the short-axis, out-of-plane technique has been shown to be more readily used by less experienced operators.9 A recent video on the subject stated that the long-axis, in-plane technique is more frequently used for USG-PIV by experienced operators10; however, in our experience, a long axis, in-plane approach is less useful for peripheral veins (regardless of operator experience level), as these veins tend to be small, are accompanied by arteries, and often do not travel in straight lines. With the out-of-plane, short axis approach, the needle tip is visualized within the vessel lumen as a hyperechoic structure, also known as the target sign (Figure 1). Obtaining a target sign does not guarantee that the needle tip is indeed intravascular and represents a potential pitfall of using this approach. At times, the vessel wall “tents” and deforms to the pressure of the needle tip but the tip remains extravascular (Video Clip S1, available as supporting information in the online version of this paper). Also, the “bull's eye” of the target sign may not always represent the true needle tip, as the ultrasound plane may be cutting across the needle more proximal to its tip. This can result in the needle tip penetrating deeper than anticipated, resulting in inadvertent puncture of the vein's posterior wall, also known as “back-walling” the needle. We propose an additional method to confirm intravascular positioning of the needle tip using an ultrasound guided out-of-plane, short-axis approach. Once a target sign is obtained, the operator should decrease the angle between the needle and skin and then advance both the needle and the catheter 1 mm to 2 mm farther while keeping the target sign centered and visualized within the vessel. As the probe is fanned distally, the bull's eye of the target sign should stay in the center of the vessel for a couple of ultrasound planes, but disappear as fanning continues distally from the point of needle entry. This confirms that the needle tip is truly intravascular and will allow for subsequent cannulation of the vessel. Video Clip S2 (available as supporting information in the online version of this paper) demonstrates the “vanishing target sign” technique of USG-PIV placement. While helpful for peripheral vascular access, this technique can also be used for any ultrasound-guided procedure necessitating precise knowledge of the location of a needle tip. It may help avoid misplacement of the needle during central vascular access as well, where location of the needle tip in the short axis is particularly important. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Multifunctional Laparoscopic Trocar With Built-in Fascial Closure and Stabilization

Multifunctional Laparoscopic Trocar With Built-in Fascial Closure and Stabilization