Thin-walled Needle Research Articles

Dislocation force of scleral flange-fixated intraocular lens haptics

PurposeTo measure the dislocation forces in relation to haptic material, flange size and needle used.SettingHanusch Hospital, Vienna, Austria.DesignLaboratory Investigation.Methods, main outcome measures30 G (gauge) thin wall and 27 G standard needles were used for a 2 mm tangential scleral tunnel in combination with different PVDF (polyvinylidene fluoride) and PMMA (polymethylmethacrylate haptics). Flanges were created by heating 1 mm of the haptic end, non-forceps assisted in PVDF and forceps assisted in PMMA haptics. The dislocation force was measured in non-preserved cadaver sclera using a tensiometer device.ResultsPVDF flanges achieved were of a mushroom-like shape and PMMA flanges were of a conic shape. For 30 G needle tunnels the dislocation forces for PVDF and PMMA haptic flanges were 1.58 ± 0.68 N (n = 10) and 0.70 ± 0.14 N (n = 9) (p = 0.003) respectively. For 27 G needle tunnels the dislocation forces for PVDF and PMMA haptic flanges were 0.31 ± 0.35 N (n = 3) and 0.0 N (n = 4), respectively. The flange size correlated with the occurring dislocation force in experiments with 30 G needle tunnels (r = 0.92), when flanges were bigger than 384 micrometres.ConclusionsThe highest dislocation forces were found for PVDF haptic flanges and their characteristic mushroom-like shape for 30 G thin wall needle scleral tunnels. Forceps assisted flange creation in PMMA haptics did not compensate the disadvantage of PMMA haptics with their characteristic conic shape flange.

Ultrasound-guided thin-wall needle technique versus cannula-over-needle technique in internal jugular vein catheterization in infants

Background Internal jugular vein (IJV) is the most common site for central venous catheter (CVC) insertion in pediatric cardiac surgery, with a lower success rate than adults. Two techniques are used, the thin-wall introducer needle (TWN) technique (Seldinger) or cannula-over-needle (CON) technique (modified Seldinger). Purpose To compare between TWN and CON techniques for the insertion of IJV CVC in infants in terms of success, number of attempts, catheter insertion time, and complications. Patients and methods One hundred and twenty infants admitted for elective cardiac surgery randomly assigned into either TWN group or CON group (60 patients each). CVC insertion was performed on the right IJV under ultrasound (US) guidance. Demographic data were recorded and infants subcategorized according to their age to less than 30 days, 2–6 months, and 7–12 months. The success rate, first attempt success, number of attempts, duration of each attempt, access time, cannulation time, and complications as assessed by US were recorded and subjected to statistical analysis. Results There were significantly higher first trial success in CON than TWN in age subgroups of less than 30 days (75 vs. 22.2%) and 2–6 months (76.5% vs. 40%) and significantly higher overall success rate in CON in the age subgroup of less than 30 days (91.7 vs. 44.4%). Significantly lower number of attempts in CON in age subgroups of less than 30 days (mean, 1.75 vs. 4.77) and 2–6 months (mean, 1.24 vs. 1.73) with significant reduction in venous hematoma were detected by US. No significant difference in cannulation time between the two techniques in any of the subgroups. Conclusion In the age group of less than 30 days, CON had higher first trial success, overall success, lower number of attempts, and lower complication rate than TWN. In the age group of 2–6 months, CON had higher first trial success, lower number of attempts, and lower complication rate than TWN. In age the group of 7–12 months, TWN offered an advantage over CON with shorter access time and duration of attempt with no other significant difference.

Sutureless 27-gauge needle-assisted transconjunctival intrascleral intraocular lens fixation: Initial experience.

Purpose:The purpose of the study was to report our initial experience with the transconjunctival Intrascleral Intraocular Lens (SFIOL) fixation with modified Yamane's double-needle technique and flanged haptics.Methods:This was a prospective interventional study that enrolled 31 consecutive patients undergoing SFIOL with the modified Yamane's technique. All patients underwent comprehensive evaluation including uncorrected and best-corrected vision, intraocular pressure, ultrasound biomicroscopy, endothelial cell density, and macular thickness using optical coherence tomography (OCT). We excluded patients with visually significant coexistent pathology such as corneal scars, macular pathology, and glaucoma.Results:The mean age of subjects was 57 ± 16.9 years and 23 were men (74%). Surgery was performed for aphakia following complicated cataract surgery in 10 eyes (32%), with lensectomy for subluxated/dislocated cataract in 6 eyes (19%), and with IOL explantation for subluxated/dislocated IOL in 15 eyes (48%). There were no intraoperative complications. Uncorrected visual acuity improved from median of 1.48 logarithm of minimum angle of resolution (logMAR) units (interquartile range [IQR] = 1.3–2 logMAR) at baseline to 0.3 logMAR (IQR = 0.2–0.4 logMAR) at 6 weeks (P < 0.001) which was maintained at 6 months. There were no significant changes in endothelial cell density (P = 0.34) and OCT-based macular thickness (P = 0.31) at 6 months. Two eyes had slight IOL decentration.Conclusion:Our initial experience suggests that the Yamane's technique for SFIOL is a simple procedure with a short-learning curve and is independent of scleral flaps, tunnels, sutures, and fibrin glue. Using widely available 27-gauge needle instead of 30-gauge thin wall needle as originally described by Yamane makes it possible for the use of various three-piece IOLs available globally. Further studies are required for widespread acceptance of this technique.

An unusual mid-shaft spinal needle defect detected accidentally.

Sir, Spinal anesthesia is preferred for the caesarean sections for safety and ease. Use of Qiuncke type small bore spinal needle is recommended.[1] Through this letter, we are highlighting an unusual and very rare mid-shaft defect of Qiuncke spinal needle detected accidentally while injecting drug. A 26 G mm × 9.0 mm Qiuncke type spinal needle (Becton Dickinson) was inserted at the L2-3 interspace for spinal anesthesia. The subarachnoid space was easily encountered. Clear, spinal fluid was observed in the hub of the needle with removal of stellate. We had started injecting 0.5% hyperbaric bupivacaine through this standard and apparently normal looking needle after aspiration of spinal fluid. While injecting bupivacaine, we noticed drug drops were trickling from mid-shaft [Figure 1]. We checked needle hub and syringe attachment. To decrease drug wastage with forceful injection we injected at very slow rate around 1 ml/s. Half ml was estimated to have spilled from the mid-shaft defect. We had loaded a volume of 4 ml. We could easily inject the estimated intrathecal dose (3 ml). Very carefully we pulled back the needle (with due care that the defective needle could break). Caesarean section proceeded uneventfully. We closely scrutinized the 26 G spinal needle after use and could not find any visible split or crack. However, water was leaking from an area of mid-shaft while injecting. Figure 1 Spinal needle showing drug leaking through mid-shaft (1) while injecting. Another drop of drug on gloves (2) With extensive literature search, we got nearly similar article published in Anesthesia in 1991.[2] The letter was followed by an explanation from a medical unit of Becton Dickinson. The spinal needle is produced by pulling down a metal tube to the appropriate diameter.[2] The 26 G spinal needle is an extremely thin-walled needle. As far as needle bore size gets smaller the wall of the needle becomes thinner. While preparing needle, presence of any small particle near needle surface can cause a nick in the needle.[2] Any small nick can cause this type of defect. Through this letter, our concerns are mid-shaft defect in a disposable spinal needle is a very rare finding. An apparently normal looking needle may be the culprit. A slow rate of injection of anesthetic drugs can reduce drug spillage in such cases. The needle can break at its mid-shaft due to defect so utmost care is to be taken, while removal of the defective needle. Finally, an automated system to check the needle wall defect will help to reduce this type of needle defects.

Cephalad malposition after central venous catheterization through right internal jugular vein

Central venous catheterization is performed in the operating room, intensive care unit and emergency room for various reasons. Internal jugular vein is preferred in the operating room due to little chance of pneumothorax and straight route for catheterization to the right atrium. We experienced a case of central venous catheter malposition to cephalad in the right internal jugular vein. A 60-year-old man, 176 cm in height and 82 kg in weight, was presented for Whipple's operation due to the bile duct cancer. After completion of anesthesia induction and intubation, patient's head was turned left in Trendelenburg position. After skin disinfection, 18 guage, 2 inch thin-walled needle was inserted at the point of sternocleidomastoid (SCM) muscle apex along with medial border of lateral head of SCM muscle about angle of 45 degree to skin without using the finder needle. At the same time, anesthesiologist's left 2nd, 3rd, and 4th fingers palpated the patient's right carotid artery for avoiding arterial puncture. However, blood was not aspirated, needle was reinserted more medial direction about angle of 70 degree to skin. After aspiration of venous blood from needle, the J shape guide wire was introduced via the guiding needle using Seldinger technique. Introduction of 20 cm of J-shaped wire was done without any problem, except some resistance at 5 cm depth of the internal jugural vein. Seven Fr double lumen catheter (Prime-S®, Sungwon medical, Cheongju, Korea) was advanced to the following J-shaped wire. Blood aspiration was done to remove the air in catheter without any resistance. Catheter was sutured at the proper site and surgery was done as planned. After the operation, the patient was transferred to an intensive care unit. Head and neck antero-posterior view X-ray was checked because the central venous catheter was not seen on chest X-ray. Antero-posterior view of the head and neck showed that central venous catheter was bent sharply to the cephalad in the right internal jugular vein (Fig. 1). We removed malpositioned catheter and reinserted central venous catheter via the same side subclavian vein. The proper position of subcalvian catheter was confirmed by a chest X-ray and the patient discharged at postoperative day 13. Fig. 1 Neck anteroposterior view shows that central venous catheter is bent sharply to the cephalad in right internal jugular vein. As one of the various complications, catheter malposition via Internal jugular vein (IJV) can be associated with central venous catheterization via IJV (5.3%) [1]. There are many case reports of malpositioning central venous catheter that were positioned in the jugular venous arch via the right subclavian vein [2], in the internal thoracic vein via the internal jugular vein [3] etc. However, this is the first case of malposition of the catheter, which was bent upward. Bending the catheter is very rare because the right internal jugular vein is the straight route for catheterization to the right atrium. Although there was some resistance during introduction of the J-shaped wire, blood aspiration via catheter was normal, dripping of the fluid seemed normal and central venous pressure curve showed no other abnormal findings. We postulate that the J-shaped wire was bent in the cephalad direction at the moment of resistance. The other postulated cause is an acute angle of the introducing needle when it punctured the internal jugular vein. We cannot rule out the anatomical variation of the external jugular vein and internal jugular vein. Deslaugiers et al. [4] reported that 60% of the external jugular vein is drained to junction of the internal jugular vein and subclavian vein, drained to the subclavian vein in 36%, and drained to the internal jugular vein in 4%. However, we did not confirm the anatomical variation with venous angiogram. It seems that we should be careful when we introduce the wire with some resistance. Malpositioning of the catheter results in monitoring inaccurate central venous pressure, damage to vascular wall, and forming the thrombus. However, the chance of thrombus formation is very low since the blood flow velocity is very fast in the internal jugular vein. In addition, it is impossible that the infused drug inflows to the brain. Although, the most precise method to confirm the complications is examination of the X-ray after the catheterization, ultrasono-guided central venous catheter placement is increasing the success rate, shortening the procedure time, decreasing the complication and the easiest method for acknowledging the direction of catheter, needle and guide wire during the entire catheterization process [5]. In summary, if there is any problem during the central venous catheterization, ultrasonography can be used for optimal catheter placement, and prevention of complications. Additionally, X-ray must be examined to confirm the position of the catheter and incidental complication.

Interventional Nephrology: Core Curriculum 2009

Interventional Nephrology: Core Curriculum 2009

Evaluation of injection force of three insulin delivery pens

Objective: Reduced injection force is among the modifications to the Next Generation FlexPen® (NGFP). This force was compared with two other prefilled pens: SoloStar® (SS) and KwikPen® (KP). Research design/methods: The injection force of the pens was measured, with either a BD Micro-Fine™ 31G thin-wall needle, or a NovoFine® 32G Tip extra thin wall needle attached. Pens of each type were tested with both needles, during injection of 20 U insulin, at speeds 3.3, 5 and 8.3 mm/s. Results: NGFP had a significantly (p < 0.05) lower mean injection force than SS or KP, at all injection speeds, with both needles. Injection forces (mean ± s.d.) with NGFP and the BD Micro-Fine™ 31G thin-wall needle were: 8.1 ± 0.7, 10.7 ± 1.4 and 15.6 ± 0.9 N at the three speeds, respectively. For SS, the corresponding values were: 9.2 ± 0.5, 13.3 ± 0.8 and 20.7 ± 2.4 N. For KP they were: 12.5 ± 1.6, 16.9 ± 1.2 and 24.5 ± 2.6 N. Attached to the NovoFine® 32G Tip extra thin wall needle, the NGFP injection forces were: 5.7 ± 0.4, 8.2 ± 0.7 and 12.7 ± 0.5 N; with SS were: 6.7 ± 0.3, 10.4 ± 2.1 and 16.3 ± 1.1 N; and with KP were: 9.1 ± 1.3, 13.1 ± 0.8 and 21.6 ± 2.0 N. The injection force with NGFP was 12 – 25% lower compared with SS and 35 – 41% lower compared with KP. Conclusions: This study shows that NGFP has a significantly lower injection force than SS or KP.

Complete cavopulmonary shunt completion after in utero balloon atrial septoplasty for hypoplastic left heart syndrome

Complete cavopulmonary shunt completion after in utero balloon atrial septoplasty for hypoplastic left heart syndrome

Quality of Life and Tolerability After Administration of Enfuvirtide with a Thin-Walled Needle: QUALITÉ Study

Purpose: Use of enfuvirtide-containing regimens leads to virologic and immunologic benefits and quality of life (QoL) improvements. This study (QUALITÉ) was designed to primarily identify baseline predictors of QoL improvements and characterize injection site reaction (ISR) signs/symptoms using a thinner/shorter needle. Method: Enfuvirtide-naïve, antiretroviral (ARV)-experienced patients with CD4 counts >50 cells/mm3 enrolled in this prospective, 12-week, multisite, open-label study. Patients self-administered enfuvirtide, 90 mg bid, using thin-walled, 31-gauge/8-mm needles in combination with other ARVs. QoL was evaluated with MOS-HIV. Results: Of the 361 patients enrolled, 346 contributed to QoL assessments. Baseline median HIV RNA and CD4 counts were 4.21 log10 copies/mL and 203 cells/mm3, respectively. Although no baseline factors were predictive of week 12 QoL improvement, 9 of 11 MOS-HIV domain scores improved significantly, including physical function (p = .0002) and mental health (p = .0006). Through week 12, 87% of patients reported ISRs; 59% and 28% reported worst pain/discomfort grade ≤1 and grade ≥2, respectively, and none were considered serious. Patients reported that self-injection minimally impacted daily functioning or activities. Conclusion: Although no predictors of QoL were identified, significant improvements in QoL were observed with minimal clinically significant ISRs (grade ≥2) using the 31-gauge/8-mm needle.

Ultrasound Guidance for Peripheral Venous Access: A Simplified Seldinger Technique

Asheville Surgery Center, Asheville, North Carolina. stonemd@charter.netOccasionally, patients for ambulatory surgery present with difficult peripheral venous access. Because only short-term access is needed, I prefer to avoid central venous cannulation and the associated risks. In these cases, I have begun using ultrasound guidance and a simplified Seldinger1technique for upper extremity peripheral venous access. A description of the technique and the results of a series of 10 procedures follows.In this technique, a tourniquet is applied to the upper arm. Alcohol or povidone iodine is used to prepare the antecubital fossa and distal upper arm. Disposable, nonsterile gloves are worn, and draping is unnecessary. A 10-5 MHz ultrasound probe (Sonosite Titan, L38; Sonosite, Bothell, WA) is covered with gel, an occlusive dressing (3M Tegaderm 10 × 12 cm; 3M, St. Paul, MN), and then additional sterile gel. Using a transverse view, an appropriate, nonthrombosed vein is identified. This may be the cephalic, basilic, or brachial vein. The brachial artery and median nerve are identified, so they can be avoided. Lidocaine is infiltrated 1–2 cm distal to the planned insertion site. I then use a spring-wire guide/catheter over needle assembly, usually used for arterial catheterization (Arrow arterial catheterization set FA-0420; Arrow International, Reading, PA). It consists of a 10.8-cm, 20-gauge catheter over a 22-gauge thin wall needle with an integral 0.46-mm-diameter spring wire guide. Using a transverse or longitudinal view and a free hand technique, the needle is inserted into the selected vein under real-time imaging. When ultrasound imaging shows the needle in the vein and venous blood flashback appears, I ask an assistant to advance the spring wire guide. Alternately, I drop the ultrasound probe and advance the wire myself. Next, the catheter is advanced over the wire, the tourniquet is released, and the needle/wire assembly is removed.Table 1shows the results of a series of 10 consecutive ultrasound-guided peripheral venous access procedures performed by the author. Patients were included in this series if at least two attempts at standard peripheral venous access failed or no adequate sized veins were visible or palpable in the upper extremity. Success was defined by the ultrasound view of the catheter in the vein and free flow of venous-appearing blood from the catheter. Each separate skin puncture was considered an attempt. Time was defined as the interval from initial skin puncture until success was achieved or the procedure was aborted. Nine of 10 catheter insertions were successful. There was an average of 1.3 attempts per procedure. The time required for a procedure averaged 140 s.Ultrasound guidance is used commonly for peripherally inserted central catheters2and occasionally for standard peripheral venous access. In emergency medicine applications, Keyes et al. 3found that a 5-cm catheter over needle infiltrated 8% of the time, and therefore, a longer catheter might be useful for these deeper veins. Sandhu and Sidhu4recommended long needle-mounted catheters or a Seldinger technique for deep veins. Using a guide wire may help to ensure that an advancing catheter enters the vein properly. However, a standard Seldinger technique takes more time and requires sterile gloves, draping, and a table to hold the wire, tissue dilator, and catheter.Ultrasound guidance for peripheral venous access may be improved by the use of a simplified Seldinger technique. The Arrow catheter set is commonly used for arterial catheterization, so anesthesiologists should be familiar with its use. The series described here demonstrates that this technique has a good success rate and the procedure takes a relatively short time to complete. Ultrasound guidance using this catheter may prevent multiple puncture attempts and decrease the use of unnecessary central venous catheters.Asheville Surgery Center, Asheville, North Carolina. stonemd@charter.net

Usability of a Microtapered Needle (TN3305) for Insulin Treatment in Japanese Patients with Diabetes Mellitus: A Comparative Clinical Study with a Standard Thin Wall Needle

We evaluated the clinical usability of a microtapered needle (TN3305, "Needle T," Terumo Corp., Tokyo, Japan) by comparing it with a standard needle (Micro-Fine +, 31 gauge, 5 mm, thin wall, "Needle B," Nippon Becton Dickinson Co., Ltd., Tokyo) in a multicenter study. Ninety-nine patients with diabetes mellitus being treated in 11 Japanese hospitals were enrolled in the study. Written consent was obtained from all patients. They were allocated randomly to two groups by an envelope (crossover) method. Injections were performed using one needle first, followed by the other needle 4 or 5 days later. Pain caused by injection was evaluated using a visual analogue scale (VAS). In the overall evaluation, Needle T was chosen by 40 patients (44.4%) and Needle B by 17 (18.8%); 33 patients (36.7%) expressed no preference. VAS scores for Needles T and B were 1.48 +/- 0.18 and 2.47 +/- 0.24 cm, respectively (P < 0.001). In this study, lower VAS indicated less pain. The preferences and VAS scores suggested that Needle T caused less pain than Needle B. The incidence of adverse events and safety were equivalent for both needles. We believe that usability of Needle T by patients for self-injection is better.

３３ゲージのテーパー型注射針を懸濁インスリン製剤が通過したときのＮＰＨ結晶の形状とインスリンの血糖降下作用への影響について

The Nanopass®33 micro-tapered needle (MT 33 G, Terumo Corp., Tokyo, Japan) is tapered in form : 33 G at the tip end and 28 G at the cartridge end. We examined the structure of insulin crystals in insulin suspensions before and after passing through the MT 33 G needle to determine if there were any changes in it that might adversely affect the pharmacodynamics and action of insulin. We also examined the hypoglycemic effect of insulin in dogs after it had passed through a MT 33 G needle to see if it had been modified by it.No changes were observed in the insulin crystal structure when the insulin preparation in a syringe was discharged at a rate of 10 units/sec through the MT 33 G needle connected to it. Also, when insulin was administered to dogs, there was no significant difference between the MT 33 G and the Micro-FineTM Plus, 31G, Thin Wall needle (Nippon Becton Dickinson Co., Ld., Tokyo, Japan) as regards the blood insulin and blood glucose levels measured.

Teaching pediatric procedures: the Vancouver model for instructing Seldinger's technique of central venous access via the femoral vein.

The way in which physicians are trained to do invasive practical procedures is an ongoing challenge for educators. Percutaneous insertion of a central line via the femoral vein using the Seldinger technique is an important practical pediatric procedure, and the need for physicians to be educated in the necessary skills is recognized in current training initiatives such as Pediatric Advanced Life Support (PALS) and Advanced Pediatric Life Support. Unfortunately, the majority of instruction in central venous access techniques is theoretic. This approach does not provide the hands-on training needed to give practitioners the necessary practical experience, or confidence in their skills. Practice using simulated tissue can enable physicians to perform practical skills with greater confidence. However, although commercially available models exist for peripheral venous access, a recent cross-Canada survey of the 13 PALS program coordinators and a similar inquiry to the American Heart Association indicated that none of them had a pediatric practice model for central venous access. We describe 1) how to construct from materials readily available a pediatric model for the insertion of central venous catheters into the femoral vein using the Seldinger technique, and 2) an evaluation of the change in confidence learning with the model engendered. In our experience, this model is inexpensive (less than $50) and can be replicated readily by others for use as a teaching aid. It provides inexperienced physicians the opportunity to learn the practical elements of the technique and acquire confidence in the Seldinger method. Our hypothesis was that the confidence and skill of physicians would be increased by practical experience of central line insertion using a realistic model. The model enables trainees to be taught the technique described in the PALS manual to locate the femoral artery. They then can learn to introduce a thin-walled needle or over-the-needle catheter, one finger's breadth below the inguinal ligament and just medial to the location of the femoral artery. The needle or over-the-needle catheter then can be advanced at the correct angle if the needle is directed toward the model's umbilicus. As occurs in vivo, the model allows for a free flow of fluid to be obtained as the "vessel" is entered. If the Foley catheter simulating the vessel is transfixed, negative pressure applied as the needle is withdrawn will result in fluid being obtained as the needle tip reenters the "vessel." The syringe then can be removed from the needle, and the key elements of the procedure-correct insertion of the Seldinger guide wire and passage of the venous catheter over the guide wire into the vessel-can be practiced. If desired, instruction also can be given on the use of a dilator and techniques of taping the catheter in place and all the appropriate techniques to avoid potential air embolism. However, the model does not lend itself to instruction in suturing. The model has been used to teach the practical elements of this technique to 428 physicians (emergency physicians, 49%; pediatricians, 24%; other physicians, 20%; pediatric residents, 7%). Their success rate for cannula insertion in three or fewer attempts was 87%. The last 218 physicians were evaluated to assess the influence of learning with the model on their confidence to perform the technique successfully in an emergency. Before training they were asked, "Have you done a pediatric resuscitation course that taught this technique in theory?" and "Rate your confidence level for performing central vascular access in a patient from 0 to 5 (none, very little, some, moderate, good, complete)." This rating was repeated after the training session using the model. For 154 (71%) answering "yes" to a previous resuscitation course, mean scores were 1.52 (standard error [SE] +/- 0.91) after theoretic instruction and 4.06 (SE +/- 0.47) after practical education using our model. The 64 (29%) physicians

Evaluation of biopsy needles and prototypic needle guide devices for percutaneous biopsy with CT fluoroscopic guidance in simulated organ tissue.

The authors evaluated accuracy and success rates for placement of fine-aspiration, core, and coaxial biopsy needles in pork meat with three needle guide devices and computed tomographic fluoroscopic guidance. Accuracy and reliability with a metallic sponge-forceps needle holder was equal to or greater than those with other devices, and it was preferred by operators due to its lighter weight and single-handed manipulation. All needle holders functioned poorly with thin-walled needles.

Antinociceptive and motor-blocking efficacy of ropivacaine and bupivacaine after epidural administration in the dog.

This study was initiated to evaluate the antinociceptive and motor blocking capabilities of epidurally administered 0.5% and 0.75% ropivacaine and bupivacaine using a blinded, random crossover design in the dog. Additionally, serum drug concentrations and serum protein binding were determined. Twelve male beagles were prepared with chronic epidural and arterial catheters under sterile conditions. The epidural space was identified by a loss-of-resistance technique using an 18-gauge thin-wall Crawford needle via the midline approach. The catheter was attached to a Schraeder-type Teflon valve sutured subcutaneously. Local anesthetic drugs were administered into the lumbar epidural space in a constant volume of 3.0 mL. Evaluation of antinociceptive and motor blocking qualities were evaluated at regular intervals. Arterial blood samples were drawn during the 15 minutes following local anesthetic injection for drug concentration and pharmacokinetic analysis. Onset time of motor block in the ropivacaine 0.5% group was longer than in other groups but not significantly different. Duration of motor and sensory block demonstrated a dose-dependent relationship of both drugs. Bupivacaine 0.5% and 0.75% produced motor block (81 +/- 42 minutes and 198 +/- 44 minutes [mean +/- SD], respectively) of significantly longer duration than corresponding concentrations of ropivacaine (69 +/- 35 minutes and 133 +/- 32 minutes, respectively). The onset times for sensory block of the vertebral dermatomes were not different between groups. No difference was found in duration of dermatomal sensory block between the 0.5% solutions. However, the duration of dermatomal sensory block was significantly longer in the bupivacaine 0.75% group than in any other group. Peak arterial serum drug concentrations were not different between drugs at equal concentrations and were reached between 2 and 6 minutes in all animals. Both drugs were highly bound to serum proteins (> 98%). No severe adverse effects or sequelae were observed. The 0.5% solutions produced similar sensory block of the vertebral dermatomes. Duration of dermatomal block with 0.75% bupivacaine was longer than with the corresponding ropivacaine concentration. Ropivacaine produced motor block of shorter duration as compared with bupivacaine. Serum concentrations of the two drugs were similar after injection of the same doses. In this animal model, ropivacaine produced shorter durations of sensory and motor block than corresponding concentrations of bupivacaine. These data are consistent with previously published data in animals and humans.

Transabdominal thin-gauge embryofetoscopy: A technique for early prenatal diagnosis and its use in the diagnosis of a case of Meckel-Gruber syndrome

Our aim was to develop and evaluate a transabdominal endoscopic technique to visualize the embryo or fetus with thin-gauge needles and submillimetric fiberoptic endoscopes. Under ultrasonographic guidance, an 18- or 19-gauge thin-wall needle was introduced into the uterus of 28 patients undergoing first-trimester or early second-trimester termination of pregnancy. A 0.7 mm endoscope was threaded through the lumen of the needle after removal of the stylet. Visualization of the embryo-fetus was attempted before 14 weeks' gestation (n = 20). From 16 to 20 weeks (n = 8), the needle and endoscope were directed to the placental insertion of the umbilical cord, and a cordocentesis was performed. Excellent visualization of the surface anatomy of fetuses from 7 to 13 weeks was obtained in 85% of cases (17/20). A diagnosis of Meckel-Gruber syndrome was made at 11 weeks' menstrual age by visualizing postaxial polydactyly and an occipital encephalocele. Endoscopically assisted cordocentesis allowed visualization of the lumen of the umbilical vein and of the blood flow within it. Endoscopic visualization of the embryo or fetus can be performed transabdominally in the first trimester with small-delivered endoscopes. This represents a clear advantage over previous endoscopic approaches to the human pregnancy. Potential applications of this technique include a precise description of fetal anatomy and physiologic features, diagnosis of anomalies, and therapeutic fetal interventions.

Inability to Thread Epidural Catheter Through Epidural Needle

Several Portex epidural kits were found to include an 18-gauge epidural needle instead of the supposed 17-gauge thin-walled needle. Consequently, the 19-gauge catheter supplied in the kit could not be threaded. In one case, a second epidural kit was opened, and the epidural space relocated using the 17-gauge thin-walled needle. In another case, a 20-guage epidural catheter was found and used instead of the 19-gauge catheter packed in the kit.

A single venipuncture technique for placement of multiple central venous catheters.

Surgeons are frequently called upon to place central venous catheters for various purposes. With the increasing used of central vein hyperalimentation, these catheters have become quite widely used. Often, critically ill patients require simultaneous infusions of vasopressors, fluids, blood and/or blood products, and hyperalimentation. In patients who have had peripheral intravenous catheters indwelling for long periods, often no peripheral access routes are available. Central venipuncture carries a definite risk of pneumothorax, hemothorax, and arterial puncture. The technique presented here allows the placement of multiple centra venous catheters via a single venipuncture. Each catheter is a completely separate venous conduit and may be used to infuse any number of substances alone or concurrently with others. Materials needed for this technique are: One 18-gauge Thinwall needle Two 20-cc Luer tip syringes Two 16-gauge 8" or 12" intravenous catheters* Two separate bags of infusion fluids and tubings One bottle 1% xylocaine Two .035" floppy end spring guidewires, 40 cm long One 8 French percutaneous dilator-introducer kit One 11 knife blade One mosquito curved hemostat Sterile towels, gauze sponges, sutures of choice, antiseptic *(This equipment is required for the placement of only two catheters).

Crystallization of sublimation products in periclase refractories in high-temperature processes

During the melting, firing, and service of magnesia refractories crystallization occurs in the sublimation products in the form of thin-walled tubes, fine films, dendrites, needles and threads of periclase, periclase-forsterite, and spinel compositions. The presence of carbon in these newly formed compounds indicates development mainly in a reducing atmosphere.

Percutaneous Cervical Central Venous Line Placement

To compare the rate of success and incidence of complications associated with two currently popular routes of percutaneous central venous cannulation, we studied 167 patient in whom either internal or external jugular vein catheterization was attempted. Internal jugular vein (IJV) catheterization (125 patients) was successful in 91%; an intrathoracic location was achieved in 100%; complications occurred in 12.8%. Complications included one case of catheter malposition, one case of tension pneumothorax, and 12 instances of inadvertent carotid artery puncture, one resulting in a paratracheal hematoma and phrenic nerve compression. The success rate of IJV cannulation was higher and carotid artery puncture less frequent when an 18-gauge thin-walled needle and a straight guide-wire were used than when IJV cannulation was performed by bind puncture with a larger over-the-needle catheter. Delayed vein perforation occurred twice. External jugular vein cannulation (42 patients), using a "J" wire technique, yielded a 76% success rate: 93.7% of catheter tips reached an intrathoracic location. No complications occurred. We conclude that IJV cannulation is a more reliable means of percutaneous central venous line placement but is associated with a significant incidence of complications which can be reduced if a technique employing a scout needle and guide-wire is used.