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1.  An analysis of the effectiveness of two topical anesthetics. 
Anesthesia Progress  1990;37(6):290-292.
This study compared the effectiveness of topical benzocaine 20%, lidocaine 5%, and a placebo in reducing the pain caused by needle insertion when the medicament was placed in the mucobuccal fold above the maxillary canine eminence. Both topical anesthetics and the placebo were randomly tested against each other bilaterally. For uniformity the agents were left in place for three minutes before needle insertion. A 27 gauge short needle mounted on an aspirating syringe was then inserted just past the bevel. Each subject rated the degree of pain on a visual analogue scale 100 mm in length. A pulse oximeter was used to record the heart rate. The results indicate that both topical anesthetics are significantly better than the placebo in reducing pain caused by needle insertion, although no statistically significant differences were found between the two topical anesthetics. Statistically significant differences in heart rate were seen, but these differences were not clinically significant. It is concluded that benzocaine 20% and lidocaine 5% significantly reduce the pain during needle insertion.
PMCID: PMC2162554  PMID: 2097909
2.  Comparison of Inferior Dental Nerve Block Injections in Child Patients Using 30-Gauge and 25-Gauge Short Needles 
Anesthesia Progress  1987;34(6):215-219.
Thirty-gauge needles are generally not recommended by dental schools, yet many dentists use them. Thin needles (30 gauge) can aspirate blood, have similar deflection to thick needles (25 gauge), and resist breakage. Measurable clinical differences between inferior dental block injections using 25-gauge or 30-gauge short needles for children is addressed in this research paper. Random allocation assigned 76 cases to 30-gauge and 62 cases to 25-gauge tribeveled. Twenty-seven-gauge short needles are in routine use for inferior dental nerve block injections in our clinics. After informed written consent was obtained, inferior dental block injections were carefully administered to children (62 males and 76 females, mean age 10 years ± 3 [SD], range 4—18 years) by faculty and students in pediatric dentistry and observed by one of two trained observers. After aspiration in two planes (180°), 0.5 mL of 2% lidocaine with 1:100,000 epinephrine was deposited in the lingual block area then 1.0 mL in the inferior dental area after touching bone. Any aspirate was recorded and subjective pain scores were taken immediately using a visual analogue scale. Five minutes after the commencement of the injection, the efficacy was tested objectively by two light needle pricks of the mucosa adjacent to the cuspid. The comparability of groups as regards age and sex was verified. Half of the injections were effective at five minutes in each group. There were no significant differences in efficacy, or pain scores. Both 25- and 30-gauge groups had nine instances of slight aspiration and two instances of more marked aspirations. The overall aspiration rate was 16%. It is concluded that 25- and 30-gauge needles do not differ significantly with respect to efficacy, pain, or aspiration. Children do not think that inferior dental nerve block injections hurt very much, and there is no evidence to support a change from 25- to 30-gauge needles.
PMCID: PMC2190042  PMID: 3481519
3.  The Incidence of Intravascular Needle Entrance during Inferior Alveolar Nerve Block Injection 
Background and aims
Dentists administer thousands of local anesthetic injections every day. Injection to a highly vascular area such as pterygomandibular space during an inferior alveolar nerve block has a high risk of intravascular needle entrance. Accidental intravascular injection of local anesthetic agent with vasoconstrictor may result in cardiovascular and central nervous system toxicity, as well as tachycardia and hypertension. 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.
Materials and methods
Three experienced oral and maxillofacial surgeons performed 359 inferior alveolar nerve block injections using direct or indirect techniques, and reported the results of aspiration. 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
15.3% of inferior alveolar nerve block injections were aspiration positive. Intravascular needle entrance was seen in 14.2% of cases using direct and 23.3% of cases using indirect block injection techniques. 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 direct or indirect block injection techniques (P = 0.127) and between right and left injection sites (P = 0.778).
Conclusion
According to our findings, the incidence of intravascular needle entrance during inferior alveolar nerve block injection was relatively high. It seems that technique and maneuver of injection have no considerable effect in incidence of intravascular needle entrance.
doi:10.5681/joddd.2008.008
PMCID: PMC3533637  PMID: 23285329
Inferior alveolar nerve; injection; local anesthesia
4.  Pharmacy Syringe Purchase Test of Nonprescription Syringe Sales in San Francisco and Los Angeles in 2010 
The two main legal sources of clean needles for illicit injection drug users (IDUs) in California are syringe exchange programs (SEPs) and nonprescription syringe sales (NPSS) at pharmacies. In 2004, California became one of the last states to allow NPSS. To evaluate the implementation of NPSS and the California Disease Prevention Demonstration Project (DPDP), we conducted syringe purchase tests in San Francisco (SF) and Los Angeles (LA) between March and July of 2010. Large differences in implementation were observed in the two cities. In LA, less than one-quarter of the enrolled pharmacies sold syringes to our research assistant (RA), and none sold a single syringe. The rate of successful purchase in LA is the lowest reported in any syringe purchase test. In both sites, there was notable variation among the gauge size available, and price and quantity of syringes required for a purchase. None of the DPDP pharmacies in LA or SF provided the requisite health information. The findings suggest that more outreach needs to be conducted with pharmacists and pharmacy staff. The pharmacies' failure to disseminate the educational materials may result in missed opportunities to provide needed harm reduction information to IDUs. The varied prices and required quantities may serve as a barrier to syringe access among IDUs. Future research needs to examine reasons why pharmacies do not provide the mandated information, whether the omission of disposal options is indicative of pharmacies' reluctance to serve as disposal sites, and if the dual opt-in approach of NPSS/DPDP is a barrier to pharmacy enrollment.
doi:10.1007/s11524-012-9713-7
PMCID: PMC3675724  PMID: 22718357
Nonprescription syringe sales; IDU; SB1159; California; Pharmacy; Policy
5.  The Washington Needle Depot: fitting healthcare to injection drug users rather than injection drug users to healthcare: moving from a syringe exchange to syringe distribution model 
Needle exchange programs chase political as well as epidemiological dragons, carrying within them both implicit moral and political goals. In the exchange model of syringe distribution, injection drug users (IDUs) must provide used needles in order to receive new needles. Distribution and retrieval are co-existent in the exchange model. Likewise, limitations on how many needles can be received at a time compel addicts to have multiple points of contact with professionals where the virtues of treatment and detox are impressed upon them. The centre of gravity for syringe distribution programs needs to shift from needle exchange to needle distribution, which provides unlimited access to syringes. This paper provides a case study of the Washington Needle Depot, a program operating under the syringe distribution model, showing that the distribution and retrieval of syringes can be separated with effective results. Further, the experience of IDUs is utilized, through paid employment, to provide a vulnerable population of people with clean syringes to prevent HIV and HCV.
doi:10.1186/1477-7517-7-1
PMCID: PMC2806876  PMID: 20047690
6.  A Micro-Advancer Device for Vitreal Injection and Retinal Recording and Stimulation 
Experimental eye research  2011;93(5):767-770.
A micro-advancer device that positions a narrow-gauge needle within the vitreous humor of the rat eye is described. The device is compact, simple and inexpensive to manufacture. It consists of an outer guard needle and an inner injection needle that is advanced through the guard needle. With the rat held in a stereotaxic holder and the globe fixed to a stabilizing ring, the outer 25-gauge guard needle is advanced through the sclera using a standard micromanipulator. The inner 31-gauge injection needle is then advanced through the guard needle with a manually controlled leadscrew and carriage mechanism. The inner injection needle is attached to a Hamilton syringe and can be positioned to within microns of the retinal surface under visual observation through a microscope. The injection needle is fixed to the device by a quick-release clamp on the carriage and can be rapidly exchanged while the guard needle remains in place in the vitreous. This permits different solutions to be injected sequentially into the vitreous humor. Recording electrodes, stimulating electrodes, and optical fibers can also be advanced through the guard needle and positioned accurately near the retinal surface or within the retina.
doi:10.1016/j.exer.2011.08.010
PMCID: PMC3233358  PMID: 21884697
Micro-advancer device; vitreous humor; retina; intraocular injection; multiple injections; recording electrode; stimulating electrode; inexpensive
7.  Connection Changes in Somatosensory Cortex Induced by Different Doses of Propofol 
PLoS ONE  2014;9(2):e87829.
Background
The mechanism by which general anesthetics, widely used in clinical practice for over 160 years, effects on sensory responsiveness has been unclear until now. In the present study, the authors sought to explore the effect of different doses of propofol on somatosensory cortex by whisker stimulation in rats.
Methods
In a fixed cage, rats were anesthetized with propofol 80 mg/kg intraperitoneally and then cathetered tail vein with 23-gauge metal needle connected with a pump. Two holes (2 mm diameter) were drilled and recording electrodes implantated in the primary somatosensory cortex barrel field (S1BF) and secondary somatosensory cortex (S2). The extracellular (20 rats) and intracellular (8 rats) recordings were used to test the neuron activity in both cortices at different doses of propofol (20, 40 and 80 mg/kg/h) through tail vein by pump. Meantime, vibrissal, olfactory, corneal responses (VOCR, sedation), and tail-pinch response (TRP, analgesia) were tested every 10 min during the doses of propofol 20, 40 and 80 mg/kg/h.
Results
VOCR and TRP were depressed by propofol in a dose-dependent manner. The amplitude by whisker stimulation in S1BF was stronger and the peak latency was shorter compared with that of in S2. The response latency of S1BF and S2 was increased by raising infusion rate of propofol with the response latency in S2 being longer than that in S1BF at the same doses of propofol. The cross-correlation between S1BF and S2 decreased as the propofol infusion rate increased. The input resistance was higher by increasing infusion rate of propofol.
Conclusion
The sedation and analgesia effects of propofol were dose-dependent. Both the connectivity and instinctive oscillation between S1BF and S2 were proportionally modulated by the different doses of propofol.
doi:10.1371/journal.pone.0087829
PMCID: PMC3917837  PMID: 24516566
8.  A simple technique for fat biopsy of PBB-exposed individuals. 
A simple nonsurgical technique of obtaining fat samples by aspiration from the gluteal prominence was developed by Hirsh in 1960 and has been in use in our Nutrition Clinic at the Mount Sinai Hospital for several years. We have modified it for field use and the analysis of fat-soluble hydrocarbon residues. All the materials which will contain the fat sample to be analyzed are washed with acetone and pesticide residue-free hexane, and a 15 gauge needle and 33 cc syringe are sterilized. Aspiration of fat from the lateral gluteal prominence is accomplished under local xylocaine anesthetic. The anesthetic also serves as the vehicle into which the fat is broken by the shearing action of the 15 gauge needle. Fat particles are sucked into the syringe by a constant vacuum kept on the syringe during lateral movement of the needle under (and parallel to) the skin within the gluteal fat pad; 200--500 ml of fat can be obtained for hydrocarbon residue analysis. The only complications have been some mild hematomas at the site of the aspiration. The method avoids surgical biopsy and sutures and takes about 7--8 min.
Images
PMCID: PMC1637465  PMID: 209973
9.  Effect of Needle Diameter and Flow Rate on Rat and Human Mesenchymal Stromal Cell Characterization and Viability 
Introduction
Current mesenchymal stromal cell (MSC) delivery methods require infusion/implantation through needles and/or catheters. Little investigation into the effect of delivery via catheter injection has been completed. We hypothesize that injection of rat and human MSCs through various clinically relevant-sized catheters and flow rates will not affect cell viability, characterization, or function.
Methods
Both rat and human MSCs were injected through 20-, 25-, and 30-gauge needles, as well through an SL-10 microcatheter at rates of 60, 120, 240, and 500 mL/h. MSC viability and apoptotic fraction was measured. MSCs were characterized 24 h after injection with flow cytometric immunophenotyping, and multilineage differentiation was completed.
Results
Catheter diameter or flow rate did not affect rat MSC viability. No clinically significant decrease in human MSC viability was observed immediately after injection; however, a delayed decrease in viability was observed at 24 h. No difference in the surface markers CD11b, CD45, CD29, CD49e, CD73, CD90, CD105, and Stro-1 or the capacity for multilineage differentiation (adipogenesis, osteogenesis, and chondrogenesis) was observed for either rat or human MSCs.
Conclusion
The injection of human and rat MSCs through various clinically relevant catheters and flow rates did not have a clinically significant effect on viability immediately after injection, indicating compliance with recently published Food and Drug Administration guidelines (viability >70%). Further, no changes in cell characterization or function were observed via measurement of cell surface markers and the capacity for multilineage differentiation, respectively. These results ensure the biocompatibility of MSCs with commonly used delivery methods.
doi:10.1089/ten.tec.2009.0423
PMCID: PMC2943405  PMID: 20001789
10.  A blunt needle (Epimed®) does not eliminate the risk of vascular penetration during transforaminal epidural injection 
Surgical Neurology International  2013;4(Suppl 5):S404-S406.
Background:
Transforaminal epidural injection of local anesthetics and corticosteroids is a common practice in patients with radicular pain. However, serious morbidity has also been reported, which can be attributed to an arterial or venous injection of the medication especially particulate glucocorticoid preparations. Using a blunt needle in contrast to sharp needle has been suggested to reduce this risk in a study on animals.
Case Description:
We present a 59-year-old female with L5 lumbar radicular symptoms and left L5-S1 foraminal narrowing who underwent transforaminal epidural injection with fluoroscopic guidance using a 22-gauge blunt curved needle (Epimed®, Johnstown, NY). Intravascular needle placement was detected during real-time contrast injection under live fluoroscopy after a negative aspiration and local anesthetic test dose. The needle was slightly withdrawn and correct distribution of the contrast was confirmed along the target nerve root and into the epidural space.
Conclusion:
This case report discusses vascular penetration utilizing an Epimed® blunt needle to perform transforaminal injections in a clinical setting. This topic was previously discussed in earlier animal studies. We also reemphasize that neither negative aspiration or local anesthetic test doses are reliable techniques to ensure the safety of transforaminal epidural injections.
doi:10.4103/2152-7806.120784
PMCID: PMC3841942  PMID: 24340239
Blunt needle; fluoroscopy; intravascular penetration; radicular pain; transforaminal epidural injection
11.  Optimizing gene transfer to conventional outflow cells in living mouse eyes 
Experimental eye research  2013;109:8-16.
The mouse eye has physiological and genetic advantages to study conventional outflow function. However, its small size and shallow anterior chamber presents technical challenges to efficient intracameral delivery of genetic material to conventional outflow cells. The goal of this study was to optimize methods to overcome this technical hurdle, without damaging ocular structures or compromising outflow function. Gene targeting was monitored by immunofluorescence microscopy after transduction of adenovirus encoding green fluorescent protein driven by a CMV promoter. Guided by a micromanipulator and stereomicroscope, virus was delivered intracamerally to anesthetized mice by bolus injection using 33 gauge needle attached to Hamilton syringe or infusion with glass micropipette connected to syringe pump. The total number of particles introduced remained constant, while volume of injected virus solution (3–10 µl) was varied for each method and time of infusion (3–40 min) tested. Outflow facility and intraocular pressure were monitored invasively using established techniques. Unlike bolus injections or slow infusions, introduction of virus intracamerally during rapid infusions (3 min) at any volume tested preferentially targeted trabecular meshwork and Schlemm's canal cells, with minimal transduction of neighboring cells. While infusions resulted in transient intraocular pressure spikes (commensurate with volume infused, Δ40–70 mmHg), eyes typically recovered within 60 minutes. Transduced eyes displayed normal outflow facility and tissue morphology 3–6 days after infusions. Taken together, fast infusion of virus solution in small volumes intracamerally is a novel and effective method to selectively deliver agents to conventional outflow cells in living mice.
doi:10.1016/j.exer.2013.01.005
PMCID: PMC3615119  PMID: 23337742
Aqueous Humor; Glaucoma; Trabecular Meshwork; Schlemm’s Canal
12.  Initial Injection Pressure for Dental Local Anesthesia: Effects on Pain and Anxiety 
Anesthesia progress  2005;52(3):95-101.
This study quantitatively assessed injection pressure, pain, and anxiety at the start of injection of a local anesthetic into the oral mucosa, and confirmed the relationship between injection pressure and pain, as well as between injection pressure and anxiety. Twenty-eight healthy men were selected as subjects and a 0.5-inch (12 mm) 30-gauge disposable needle attached to a computer-controlled local anesthetic delivery system (the Wand) was used. A 0.5 mL volume of local anesthetic solution was injected submucosally at a speed of either 30 or 160 s/mL. Three seconds after the start of local anesthetic injection, injection pressure was measured and pain and anxiety were assessed. Injection pressure was measured continuously in real time by using an invasive sphygmomanometer and analytical software, and pain was assessed on the Visual Analogue Scale and anxiety on the Faces Anxiety Scale. A significant correlation was evident between injection pressure and pain (rs = .579, P = .00124) and between intensity of injection pressure and state anxiety (rs = .479, P = .00979). It is therefore recommended that local anesthetic be injected under low pressure (less than 306 mm Hg) to minimize pain and anxiety among dental patients.
doi:10.2344/0003-3006(2005)52[95:IIPFDL]2.0.CO;2
PMCID: PMC1586792  PMID: 16252739
Local anesthetic initial injection pressure; Pain; Anxiety
13.  Teaching medical students and residents how to inject local anesthesia almost painlessly 
The objective of the present study was to determine whether it is possible to consistently and reliably teach medical students and resident learners how to administer local anesthetics in an almost painless manner. Using the published technique, 25 consecutive medical students and residents were taught how to inject local anesthetics for carpal tunnel release by watching the senior author perform the technique once. The learner then independently administered the anesthesia to the next patient who then scored the learner’s ability to inject the local anesthetic from a pain perspective. The teaching technique is demonstrated in an accompanying online video. The learners were consistently capable of administering local anesthetics with minimal pain. During the injection process, the patients only felt pain once (‘hole-in-one’) 76% of the time. This pain was attributed to the first 27-gauge needle poke. The other 24% of the time, patients felt pain twice (eagle) during the 5 min injection process. All 25 patients rated the entire pain experience to be less than 2/10. Eighty-four per cent of the patients indicated that the experience was better than local anesthetic given at the dentist’s office. Medical students and residents can quickly and reliably learn how to administer local anesthesia for carpal tunnel release with minimal pain to the patient.
PMCID: PMC3433813  PMID: 23997583
Carpal tunnel release; Local anesthesia; Medical education; Wideawake surgery
14.  Comparison of Clinically Relevant Technical Attributes of Five Insulin Injection Pens 
Background
Insulin injection pens are the predominant devices for insulin delivery in Europe and Japan because of their ease of use and convenience. This study compared clinically relevant technical attributes of durable insulin pens that are important to people with diabetes, specifically functions relating to cartridge-fitting, dose-setting, and dose-delivery on NovoPen® 4, ClikStar®, HumaPen Luxura®, Itango®, and Biosulin® Pen.
Methods
Frequency components and duration of audible clicks on dose setting and injection were measured using audio equipment when setting and delivering 20 IU of insulin. To assess cartridge-fitting torque, each pen was attached to a torque gauge via the attached needle, and torque was measured with each 180° turn as the cartridge was screwed into the body of the pen. Rotary torque of the dose-setting dial was measured when setting the dose to the maximum dose unit of the pen. Injection force was measured when delivering 20 IU at 5 mm/s in a vertical position and at a tilt of 14.7° from vertical.
Results
Audible clicks on dose-setting and dose-delivery were most distinguishable on NovoPen 4, while NovoPen 4 and ClikStar had generally lower cartridge-fitting torque and injection (both vertical and angled) force values.
Conclusion
Overall, the results showed that durable insulin pens such as NovoPen 4 have useful features related to assembly, dose-setting, and injection, which may facilitate ease of use for diabetes patients, particularly elderly patients and those with visual and/or manual dexterity impairments.
PMCID: PMC3208882  PMID: 22027319
audible clicks; cartridge-fitting torque; diabetes management; dose-setting dial torque; injection force; insulin pen
15.  Anesthetic Cartridge System Under Evaluation 
Anesthesia Progress  1981;28(1):5-10.
The problem of glass breakage in the local anesthetic cartridge system was evaluated under laboratory conditions with a mechanical testing machine. The anticipated breakage of the glass did not occur with any frequency, as the rubber stopper produced more uniform failures of the system. The glass cartridge appeared to be quite reliable and resistant to breakage.
Local anesthetics have been used for many years to provide patients temporary freedom from pain. Local anesthetic solutions are in wide use in both dentistry and medicine and are the most frequently used drugs in dentistry. Various estimates place the number of injections at approximately one half million daily or 125 million injections per year.
These drugs and the armamentarium necessary to administer them have proven to be safe and reliable. Only rarely are there reports of sensitivity to the anesthetic solution or breakage of needles.. Sterility of the solutions has not been a problem as they are carefully processed and evaluated at the factory. Although there are sporadic reports of loss of sterility, this has been attributed to the reuse of the anesthetic cartridges on more than one patient. Monheim states “The success of the cartridge system in dentistry has been due to the sincerity, honesty, and high standards of the manufacturers in giving the profession a near-perfect product.” However, on occassion a glass cartridge will break or shatter when inserting the harpoon into the rubber stopper or even during injection. Cooley et al reported on eye injuries occurring in the dental office, one of which was due to glass from a local anesthetic cartridge that exploded and propelled particles into the patient's eye. Forrest evaluated syringes, needles, and cartridges and reported that one brand (made in Britain) fractured more often than any other, but that the fracture rate was too low to be of any consequence.
It is apparent that glass cartridges will fracture or burst from time to time. This study evaluates the cartridge system with carefully controlled laboratory procedures. The cartridges were tested under various pressures and conditions in an attempt to determine the causes of failure and when such failure may be anticipated.
Images
PMCID: PMC2235753  PMID: 6939350
16.  Effect of needle size on immunogenicity and reactogenicity of vaccines in infants: randomised controlled trial 
BMJ : British Medical Journal  2006;333(7568):571.
Objectives To assess the immunogenicity of vaccines for infants and to investigate whether the incidence of reactogenicity is reduced after each immunisation dose using needles of varying lengths and gauges.
Design Randomised controlled trial.
Setting 18 general practices within two UK primary care trusts.
Participants 696 healthy infants vaccinated at 2, 3, and 4 months of age, with follow-up to 5 months of age.
Interventions Combined diphtheria, tetanus, whole cell pertussis, and Haemophilus influenzae type b vaccine and a serogroup C meningococcal glycoconjugate vaccine administered using either a wide, long needle (23 gauge/0.6 mm diameter, 25 mm), a narrow, short needle (25 gauge/0.5 mm diameter, 16 mm), or a narrow, long needle (25 gauge, 25 mm).
Main outcome measures Local and general reactions recorded by parents for three days after each dose; and diphtheria, tetanus, and H influenzae type b antibody concentrations and functional antibody against serogroup C Neisseria meningitidis 28-42 days after the third dose.
Results Local reactions to diphtheria, tetanus, whole cell pertussis, H influenzae type b vaccinations decreased significantly with wide, long needles compared with narrow, short needles. At all three doses one less infant experienced local reactions at days 1, 2, or 3 for every six to eight vaccinated. Significantly fewer infants vaccinated with the long needle experienced severe local reactions. Non-inferiority of the immune response was shown using a wide, long needle rather than a narrow, short needle for serogroup C meningococcal glycoconjugate vaccine and for diphtheria but not for H influenzae type b or tetanus, although no evidence was found of a decrease. Little difference was found between needles of the same length but different gauges in local reaction or immune response.
Conclusions Long (25 mm) needles for infant immunisations can significantly reduce vaccine reactogenicity at each dose while achieving comparable immunogenicity to that of short (16 mm) needles.
Trial registration Current Controlled Trials ISRCTN62032215.
doi:10.1136/bmj.38906.704549.7C
PMCID: PMC1570021  PMID: 16891328
17.  Aspiration biopsy of carcinoma of the pancreas. 
Gut  1975;16(8):645-647.
Peroperative pancreatic aspiration biopsies were performed on 21 patients with pancreatic lesions using a standard 20-ml disposable syringe and a 21-gauge needle. No complications were recorded which could be attributed to this procedure. A further 10 aspiration biopsies were carried out on postmortem specimens in an attempt to determine the accuracy of this method in the diagnosis of carcinoma of the pancreas. It is concluded that peroperative pancreatic needle biopsy is a safe procedure which is easily performed without special instruments. In can be of enormous value to the surgeon in planning the treatment of patients with pancreatic lesions. In cases where there is an operable mass in the pancreas it offers a simple and quick method of determining the presence of malignant cells and thus definitive surgery may be performed with confidence. For the inoperable cases it offers a method of histological confirmation of the operative findings.
PMCID: PMC1411021  PMID: 1102401
18.  Examination Of The Law Of Grotthus-Draper: Does Ultrasound Penetrate Subcutaneous Fat In Humans? 
Journal of Athletic Training  1993;28(3):246-250.
One benefit of ultrasound over infrared modalities is its ability to penetrate subcutaneous fat. The purpose of this study was to compare tissue temperature rise during ultrasound treatments in humans with various thicknesses of subcutaneous fat in the medial gastrocnemius. Twenty males served as subjects. A 23-gauge hypodermic needle microprobe was inserted 3-cm deep into the medial portion of the anesthetized gastrocnemius, and connected to a thermocouple temperature gauge. We applied 15 ml of ultrasound gel, preheated to body temperature (37°C), to a 10-cm-diameter target area. Continuous ultrasound was delivered topically at 1.5 W/cm2 for 10 minutes. During this time, the soundhead was moved at a speed of 4 cm per second, and the temperature was recorded every 30 seconds. The mean baseline temperature for all subjects was 35.4°C. The mean temperature increase was 4.9°C. We performed a regression analysis to test for correlation between fat thickness and tissue temperature rise of subjects. There was a small positive but insignificant correlation (r=.128). This supports the claim of Grotthus and Draper. Since subcutaneous fat does not serve as a barrier to therapeutic ultrasound, athletic trainers and physical therapists can expect comparable increases in muscle temperature when using this modality on people with varying thicknesses of adipose tissue.
Images
PMCID: PMC1317721  PMID: 16558239
19.  Effectiveness of 20% benzocaine as a topical anesthetic for intraoral injections. 
Anesthesia Progress  2003;50(4):159-163.
The use of topical anesthetics has been advocated prior to the administration of various types of anesthetic injections. Reported results have varied between studies. The purpose of this study was to compare the effectiveness of 20% benzocaine in reducing the pain of needle insertion during maxillary posterior and anterior infiltration and inferior alveolar nerve block injections. In this retrospective study, 1080 patients received 2336 injections using a 27-gauge needle. Topical anesthetic was applied prior to 720 of the injections. Patients rated pain of needle insertion using a 0-4 pain scale. Logistic regression analysis showed no differences in pain ratings between topical and no topical groups for the inferior alveolar nerve block and posterior maxillary infiltration injections. The use of topical anesthetic did reduce the pain of needle insertion with the maxillary anterior injections (P = .0041).
PMCID: PMC2007446  PMID: 14959903
20.  A Prospective Comparison of EUS-Guided FNA Using 25-Gauge and 22-Gauge Needles 
Background and Aims. There are limited data on the differences in diagnostic yield between 25-gauge and 22-gauge EUS-FNA needles. This prospective study compared the difference in diagnostic yield between a 22-gauge and a 25-gauge needle when performing EUS-FNA. Methods. Forty-three patients with intraluminal or extraluminal mass lesions and/or lymphadenopathy were enrolled prospectively. EUS-FNA was performed for each mass lesion using both 25- and 22-gauge needles. The differences in accuracy rate, scoring of needle visibility, ease of puncture and quantity of obtained specimen were evaluated. Results. The overall accuracy of 22- and 25-gauge needle was similar at 81% and 76% respectively (N.S). Likewise the visibility scores of both needles were also similar. Overall the quantity of specimen obtained higher with the 22-gauge needle (score: 1.64 vs. P < .001). However the 25-gauge needle was significantly superior to the 22-gauge needle in terms of ease of puncture (score: 1.9 vs. 1.29, P < .001) and in the quantity of specimen in the context of pancreatic mass EUS-FNA (score: 1.8 vs. 1.58, P < .05). Conclusion. The 22-gauge and 25-gauge needles have similar overall diagnostic yield. The 25-gauge needle appeared superior in the subset of patients with hard lesions and pancreatic masses.
doi:10.1155/2009/546390
PMCID: PMC2786003  PMID: 19997511
21.  A New Self Aspirating Plunger* 
Anesthesia Progress  1975;22(5):158-161.
In another approach to the problem of aspiration before injection of local anesthetics, a new self aspirating plunger was designed. It is composed of similar materials currently in use. Its action is simply the elastic return of a temporarily stretched diaphragm in the center of the plunger. A gentle pressure and release will cause aspiration. No harpoon is used; therefore the cartridge can be more quickly loaded and changed. No special syringe is needed.
Stanley C. Harris has said, “one of the most insidious dangers in therapeutics is the complacency which develops when undesirable reactions are infrequent. With local anesthesia, this complacency is intensified by the knowledge that local anesthetics are given intravenously by intention in certain medical procedures. However, when this procedure is employed, the patient is hospitalized, in an operating room with emergency equipment and drugs instantly available.”1
Dentists are aware of the possible consequences of intravascular injection of local anesthetics and know that these can range from lack of anesthesia to an unplesant experience or to a rare lethal one.2-3 Case histories of complications of intravascular injection appear regularly in the literature. The presence of the anesthetic in the blood can easily be demonstrated.4
Images
PMCID: PMC2516732  PMID: 1060391
22.  Low Viscosity Highly Concentrated Injectable Nonaqueous Suspensions of Lysozyme Microparticles 
Subcutaneous injection of concentrated protein and peptide solutions, in the range of 100–400 mg/mL, is often not possible with a 25- to 27-gauge needle, as the viscosity can be well above 50 cP. Apparent viscosities below this limit are reported for suspensions of milled lysozyme microparticles up to nearly 400 mg/mL in benzyl benzoate or benzyl benzoate mixtures with safflower oils through a syringe with a 25- to 27-gauge needle at room temperature. These apparent viscosities were confirmed using a cone-and-plate rheometer. The intrinsic viscosity regressed from the Kreiger–Dougherty model was only slightly above the Einstein value of 2.5, indicating the increase in viscosity relative to that of the solvent was caused primarily by the excluded volume. Thus, the increases in viscosity from electrical double layer interactions (electroviscous effects), solvation of the particles, or deviations of the particle shape from a spherical geometry were minimal, and much smaller than typically observed for proteins dissolved in aqueous solutions. The small electroviscous effects are expected given the negligible zeta potential and thin double layers in the low dielectric constant organic solvent. The suspensions were resuspendable after a year, with essentially constant particle size after two months as measured by static light scattering. The lower apparent viscosities for highly concentrated protein suspensions relative to protein solutions, coupled with these favorable characteristics upon resuspension, may offer novel opportunities for subcutaneous injection of therapeutic proteins.
doi:10.1021/la9023426
PMCID: PMC3040681  PMID: 19803503
23.  Blunt needle revision with viscoelastic materials via the anterior chamber for early failed filtering blebs after trabeculectomy 
Purpose
To report a new technique of blunt needle revision with viscoelastic materials via the anterior chamber for the treatment of early failed filtering blebs and elevated intraocular pressure after trabeculectomy, in which digital ocular massage and laser suture lysis have been ineffective.
Methods
A 27-gauge blunt needle attached to a syringe containing viscoelastic material was inserted into the anterior chamber from the inferior paracentesis. The needle tip was inserted into the subscleral flap space from the filtering fistula at the anterior chamber side, and the scleral flap was lifted bluntly. The needle tip was then inserted into the subconjunctival space where the viscoelastic agent was injected and the adhesion between the sclera and conjunctiva was separated bluntly. Blunt needle revision via the anterior chamber was performed 14 times in six eyes of six patients at Saitama Medical Center, Jichi Medical University from January 2007 to May 2009. All procedures were performed within 1 month after trabeculectomy.
Results
The intraocular pressure remained 21 mmHg or lower for more than 6 months in three of six eyes. Slight bleeding from the iris occurred in one of the 14 procedures, and hypotony (intraocular pressure below 5 mmHg) occurred in one of the 14 procedures. No serious complications developed.
Conclusion
Blunt needle revision via the anterior chamber for early failed filtering blebs is a new, simple, and safe procedure.
doi:10.2147/OPTH.S31548
PMCID: PMC3392926  PMID: 22791972
glaucoma; trabeculectomy; filtering bleb; needle revision; blunt needle
24.  Gow-Gates Technique: A Pilot Study for Extraction Procedures With Clinical Evaluation and Review 
Anesthesia Progress  2008;55(1):2-8.
The aim of this study was to compare the effectiveness of 2 different volumes of anesthetic solution for a premolar-molar extraction, and to determine the onset of complete mandibular conduction anesthesia via a Gow-Gates mandibular block. One operator performed 32 blocks with a 27-gauge needle on patients who required a dental extraction: 16 blocks using 1.8 mL of anesthetic solution, and 16 blocks using 3.6 mL of anesthetic solution. The parameters evaluated were frequency of successful anesthesia and onset of complete anesthesia. Significant differences (P < .005) were observed in the evaluation of volume: the 3.6 mL group yielded a higher success rate (82.5%) than the 1.8 mL group (17.5%). The onset of complete conduction anesthesia was achieved in 8 minutes by 56% of the subjects (9 of 16) with 3.6 mL and only one subject in 16 (6%) with 1.8 mL. A larger volume of anesthetic solution (3.6 mL) is required to achieve a higher success rate and a faster onset of action for a dental extraction without the use of reinforcement anesthesia. The volume of anesthetic solution is indirectly proportional to the onset of complete anesthesia. A premolar-molar extraction can be done, with 3.6 mL of anesthetic solution, in more than 50% of the patients 8 minutes after injection.
doi:10.2344/0003-3006(2008)55[2:GTAPSF]2.0.CO;2
PMCID: PMC2268886  PMID: 18327969
Gow-Gates; Mandibular conduction anesthesia; Mandibular block; Onset of complete anesthesia; Needle deflection
25.  Foreign bodies in the ear: a simple technique for removal analysed in vitro 
Emergency Medicine Journal : EMJ  2005;22(4):266-268.
Objective: Foreign bodies in the ear are mainly encountered in children. This can often pose a problem especially in an accident and emergency department where a microscope or expert help is not routinely available. This paper presents a simple, safe, and effective way of ear syringing. The ease and simplicity of the procedure along with the equipment are described.
Method and result: The equipment consists of a "disposable" sterile kit, consisting of a 20 ml syringe, saline at body temperature and 14 or 16 gauge cannula (without the needle). An in vitro experiment was conducted to calculate the pressure generated by the water jet on the eardrum. The pressure was well below the pressure required to burst a tympanic membrane, and hence this technique is safe to use.
Conclusions: Ear syringing is an effective and easy way of removing most foreign bodies. A detailed history and an otoscopic examination must precede the procedure. The novel method of syringing described in this paper with the usual safeguards could be a useful adjunct in the management of this common condition.
doi:10.1136/emj.2004.015016
PMCID: PMC1726719  PMID: 15788826

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