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1.  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
2.  Intravenous cannulation: a different approach. 
Anesthesia Progress  1993;40(1):20-22.
This article presents a different method of venous cannulation. It has been used successfully to teach dental residents working on pediatric and developmentally disabled patients. The technique includes using a syringe of 1% lidocaine hydrochloride attached to a 25-ga needle to produce a skin wheal by "jet injection." This is accomplished by placing the bevel of the needle downward and forcing the syringe in a downward and backward direction, with pressure being continuously exerted on the plunger. A 20-ga, 1 1/4-inch catheter is then attached to the syringe containing the remaining lidocaine hydrochloride. The catheter is bent, with its bevel up, approximately three-fourths of the way from the tip to form a gradually sloping bend of approximately 40 degrees to 45 degrees. The catheter is then inserted into the skin wheal and advanced into the vein. The advantages of this technique are that it (1) can eliminate the pain associated with a subcutaneous infiltration of a local anesthetic solution, (2) provides a method of venous cannulation that is easier to master by the novice, and (3) gives a visual check on successful catheterization of the vein.
Images
PMCID: PMC2148630  PMID: 8185086
3.  The results of Ramstedt's operation: room for complacency? 
The results of 101 pyloromyotomies performed from 1972 to 1980 have been analysed; 34 operations were performed using local anaesthesia and 67 using general anaesthesia. The use of local anaesthesia was not associated with any advantage related to postoperative or other complications. A high postoperative complication rate of 20% was found (excluding postoperative vomiting), and there were 2 deaths; 11 patients suffered wound infection, with Staphylococcus aureus isolated from 5 of these wounds. The use of prophylactic antibiotics active against Staphylococcus aureus is suggested.
PMCID: PMC2492724  PMID: 6742742
4.  LULL(ed) into complacency: a perspective on licenses and stem cell translational science 
The US has had a very successful model for facilitating the translation of a basic discovery to a commercial application. The success of the model has hinged on providing clarity on ownership of a discovery, facilitating the licensing process, providing adequate incentive to the inventors, and developing a self-sustaining model for reinvestment. In recent years, technological, political, and regulatory changes have put strains on this model and in some cases have hindered progress rather than facilitated it. This is particularly true for the nascent field of regenerative medicine. To illustrate this, I will describe the contributing practices of several different entities, including universities, repositories, patent trolls, and service providers. It is my hope that the scientific community will be motivated to coordinate efforts against these obstacles to translation.
doi:10.1186/scrt309
PMCID: PMC3854754  PMID: 23953837
5.  XDR-TB in South Africa: No Time for Denial or Complacency 
PLoS Medicine  2007;4(1):e50.
Singh and colleagues discuss the threat to regional and global public health posed by XDR-TB in KwaZulu-Natal, and propose new measures to control the outbreak.
doi:10.1371/journal.pmed.0040050
PMCID: PMC1779818  PMID: 17253901
6.  Bimanual grasp planning reflects changing rather than fixed constraint dominance 
We studied whether motor-control constraints for grasping objects that are moved to new positions reflect a rigid constraint hierarchy or a flexible constraint hierarchy. In two experiments, we asked participants to move two plungers from the same start locations to different target locations (both high, both low, or one high and one low). We found that participants grasped the plungers symmetrically and at heights that ensured comfortable or easy-to-control end postures when the plungers had the same target heights, but these grasp tendencies were reduced when the plungers had different target heights. In addition, when the plungers had different mass distributions, participants behaved in ways that suggested still-different emphases of the relevant grasp constraints. When the plungers had different mass distributions, participants sacrificed bimanual symmetry for end-state comfort. The results suggest that bimanual grasp planning relies on a flexible rather than static hierarchy. Different constraints take on different degrees of importance depending on the nature of the task and on the level of task experience. The results have implications for the understanding of perceptual-motor skill learning. It may be that one mechanism underlying such learning is changing the priorities of task constraints.
doi:10.1007/s00221-010-2368-2
PMCID: PMC2923322  PMID: 20658129
Action planning; Bimanual control; Grasping; Object manipulation; Constraint dominance
7.  Incidence of intravascular insertion in thoracic epidural catheterization by using real time fluoroscopy 
Korean Journal of Anesthesiology  2012;62(3):251-255.
Background
Epidural analgesia is commonly used to provide several types of pain relief. Although this technique has been widely used with many advantages, currently the complications appear to be increasing. Especially, inadvertent intravascular cannulation and intravascular local anesthetic administration can lead to fatal consequences.
Methods
Data was collected on 296 patients undergoing elective thoracic or abdominal surgery. Two detection methods were utilized to confirm the epidural intravascular cannulation; flashback and aspiration of indwelling catheter, and injection of a contrast agent through the catheter under fluoroscopy were used to guide the placement of the catheter and to examine the intravascular cannulation.
Results
Epidural intravascular cannulation was reported in 4 out of 296 cases (1.4%), and 1 patient underwent subdural cannulation. Among the 4 cases of epidural intravascular cannulation, two were confirmed by the flashback and aspiration methods, while the remaining cases were only detected by real time fluoroscopy.
Conclusions
In this study, inadvertent epidural intravascular cannulation occurred by as much as 1.4% of thoracic epidural catheterization. Utilizing real time fluoroscopy in addition to flashback and aspiration can enhance the sensitivity of detection.
doi:10.4097/kjae.2012.62.3.251
PMCID: PMC3315655  PMID: 22474552
Analgesia; Blood vessels; Catheters; Epidural space; Thorax
8.  A clinical comparison of pain perception and extent of area anesthetized by Wand® and a traditional syringe 
Background:
In the contemporary dental practice, alleviation of pain is the most important factor to ameliorate patient's condition and to gain one's confidence towards the skills of the operator. Such confidence aids to the ultimate success of the treatment procedures.
Aims and Objectives:
This study compares the pain response of a group of 10 subjects to the Wand® with the response to traditional syringe injections and also compares the extent of the area anesthetized.
Materials and Methods:
10 subjects were selected for the study and 20 injections were given contralaterally to them, 10 with Wand®, and rest with the traditional aspirating syringe. Each subject received 2 injections on the palate, Left side with Wand® (test) and Right side with Traditional syringe (control). All injections were given by the same investigator without the use of topical anesthetic spray/gel. Pain perception levels were recorded with a visual analogue scale. Also the extent of area anesthetized with a single palatal injection was assessed by probing.
Results:
The results showed injections with the syringe were more painful than injections with the Wand® in 2 of 10 subjects. Also the extent of the area anesthetized by both the techniques was similar except in 2 patients.
Conclusion:
The Wand® results in less painful injections; however, mean ratings of pain for both the groups, were mostly below the annoying level of pain. Also, the areas covered by the anesthetic effect of both the injections were comparatively similar.
doi:10.4103/0972-124X.99263
PMCID: PMC3459500  PMID: 23055586
Anesthesia; pain; pain perception; visual analogue scale; Wand® technique
9.  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
10.  First injection of ketamine among young injection drug users (IDUs) in three U.S. cities 
Drug and alcohol dependence  2006;87(2-3):183-193.
Ketamine, a dissociative anesthetic, has emerged as an increasingly common drug among subgroups of young injection drug users (IDUs) in cities across the United States. In-depth qualitative interviews were conducted with 213 young IDUs aged 16–28 years recruited in New York, New Orleans, and Los Angeles between 2004 and 2006. While some initiated injection drug use with ketamine, the drug was more frequently injected by IDUs with extensive polydrug using histories. IDUs initiating with ketamine commonly self-injected via an intramuscular mode of administration. The injection group provided crucial knowledge and material resources that enabled the injection event to occur, including ketamine, syringes, and injection skills. Injection paraphernalia was commonly shared during the first injection of ketamine, particularly vials of pharmaceutically-packaged liquid ketamine. Injection events infrequently occurred in a rave or club and more typically in a private home, which challenges ketamine’s designation as a ‘club’ drug. The first injection of ketamine was a noteworthy event since it introduced a novel drug or new mode of administration to be further explored by some, or exposed others to a drug to be avoided in the future. Risk reduction messages directed towards young IDUs should be expanded to include ketamine.
doi:10.1016/j.drugalcdep.2006.08.015
PMCID: PMC1852477  PMID: 16979848
Injection drug use; High-risk youth; Ketamine; Qualitative research; HIV
11.  Hypothermic manipulation of bone cement can extend the handling time during vertebroplasty 
Background
Polymethylmethacrylate (PMMA) is commonly used for clinical applications. However, the short handling time increases the probability of a surgeon missing the crucial period in which the cement maintains its ideal viscosity for a successful injection. The aim of this article was to illustrate the effects a reduction in temperature would have on the cement handling time during percutaneous vertebroplasty.
Methods
The injectability of bone cement was assessed using a cement compressor. By twisting the compressor, the piston transmits its axial load to the plunger, which then pumps the bone cement out. The experiments were categorized based on the different types of hypothermic manipulation that were used. In group I (room temperature, sham group), the syringes were kept at 22°C after mixing the bone cement. In group 2 (precooling the bone cement and the container), the PMMA powder and liquid, as well as the beaker, spatula, and syringe, were stored in the refrigerator (4°C) overnight before mixing. In group 3 (ice bath cooling), the syringes were immediately submerged in ice water after mixing the bone cement at room temperature.
Results
The average liquid time, paste time, and handling time were 5.1 ± 0.7, 3.4 ± 0.3, and 8.5 ± 0.8 min, respectively, for group 1; 9.4 ± 1.1, 5.8 ± 0.5, and 15.2 ± 1.2 min, respectively, for group 2; and 83.8 ± 5.2, 28.8 ± 6.9, and 112.5 ± 11.3 min, respectively, for group 3. The liquid and paste times could be increased through different cooling methods. In addition, the liquid time (i.e. waiting time) for ice bath cooling was longer than for that of the precooling method (p < 0.05).
Conclusions
Both precooling (i.e. lowering the initial temperature) and ice bath cooling (i.e. lowering the surrounding temperature) can effectively slow polymerization. Precooling is easy for clinical applications, while ice bath cooling might be more suitable for multiple-level vertebroplasty. Clinicians can take advantage of the improved injectability without any increased cost.
doi:10.1186/1471-2474-13-198
PMCID: PMC3524464  PMID: 23072273
Bone cement; Precooling; Ice bath; Working time; Handling time
12.  Epidural loss-of-resistance biomechanics: an open pilot cadaver study 
Purpose
We measured dynamic biomechanics of loss-of-resistance (LOR) epidural placement in prone cadavers, focussing on the period immediately following LOR, to estimate forces acting on the tissue of the epidural space.
Methods
An epidural syringe with 17G Hustead needle was instrumented to track force on the plunger, pressure in the chamber, and movement of barrel and plunger. Insertions were attempted in five formalin-preserved cadavers from T2–3 to L4–5, using LOR with saline or air, and confirmed with X-ray.
Results
Sixteen insertions were successful. Soft tissues in formalin-preserved cadavers are much harder than in living humans. With continuous pressure on the plunger, fluid thrust through the needle at the point of LOR was significantly greater (P = 0.005) with saline (mean ± standard deviation [95% confidence intervals]: 19.3 ± 14.9 [8.3 to 30.3] N); than with air (0.17 ± 0.25 [0 to 0.39] N). Stress exerted on epidural tissue was similar (air = 7792 ± 920 [6986 to 8598] Pa; saline = 7378 ± 3019 [5141 to 9614] Pa); and in both cases was greater than the stress exerted by cerebrospinal fluid pushing outwardly on the dura (4800 Pa).
Conclusion
Formalin-preserved cadavers are too stiff to make them an experimental model from which we can generalize to live humans, although we were successful in entering the epidural space and testing the instrumentation for further studies on live animals or humans. Continuous pressure on the plunger while advancing the epidural needle may “blow” the dura away from the needle tip and help prevent dural puncture. Better results are seen with saline rather than air.
doi:10.2147/LRA.S11932
PMCID: PMC3417955  PMID: 22915876
epidural anesthesia; cadaver; spinal headache
13.  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
14.  Injector for highly viscous silicone oil. 
A syringe device for the injection and evacuation of highly viscous silicone oil was developed. The problem of removing the air interfering with these manoeuvres was solved by providing special outlets in the plunger and handle of a conventional glass syringe. A slightly modified commercial motor perfusor was chosen to power this device, which has proved to be good and fail-safe in more than 100 cases.
Images
PMCID: PMC504124  PMID: 1995035
15.  Injectability Evaluation: An Open Issue 
AAPS PharmSciTech  2011;12(2):604-609.
The current work aimed to propose a system of scoring to rationalize and support the selection of the optimal diameter and length of needles. Four formulations at different viscosity and needles ranging from 21 to 26 G and length ranging from 16 to 40 mm were used. Plunger-stopper breakloose force, maximum force (Fmax), and dynamic glide force were measured by a texture analyzer at the crosshead speed of 1 mm/s. Testing was carried out into air or human subcutaneous tissue. The manual injectability of the highest viscosity product was assessed by ten evaluators. The comparison of the panel test score and the quantitative measurements of the forces permitted to score a given needle-syringe-formulation system keeping also in consideration the pressure created in the subcutaneous space and muscles at the injection site. In particular, the following relationship was drawn: at the Fmax up to 250 mPa, the injection was practically impossible; at Fmax ranging from 160 to 250 mPa, the injection was very difficult; at Fmax in the 125–160 mPa range, the injection was feasible, though with some difficulty; when the values of Fmax were lower 125 mPa, the injection went smoothly. On the basis of these preliminary data, a system of scoring the needle-syringe-formulation system is proposed to rationalize and support the selection of the optimal diameter and length of needles, keeping also in consideration the pressure created in the subcutaneous space and muscles at the injection site.
doi:10.1208/s12249-011-9625-y
PMCID: PMC3134656  PMID: 21553165
injectability; panel test; texture analyzer
16.  Avoidance of 20% carbon dioxide-enriched air with humans. 
Four college students were exposed to a Sidman avoidance procedure to determine if an avoidance contingency involving 20% carbon dioxide-enriched air (CO2) would produce and maintain responding. In Phase 1, two conditions (contingent and noncontingent) were conducted each day. These conditions were distinguished by the presence or absence of a blue or green box on a computer screen. In the contingent condition, CO2 presentation were delivered every 3 s unless a subject pulled a plunger. Each plunger pull postponed CO2 presentations for 10 s. In the noncontingent condition, CO2 presentations occurred on the average of every 5 min independent of responding. Following stable responding in Phase 1, condition-correlated stimuli were reversed. In both conditions, plunger response rate was high during the contingent condition and low or zero during the noncontingent condition. Furthermore, subjects avoided most CO2 presentations. However, CO2 presentations did not increase verbal reports of fear. Overall, the results from the present study suggest that CO2 can be used effectively in basic studies of aversive control and in laboratory analogues of response patterns commonly referred to as anxiety.
doi:10.1901/jeab.1998.70-79
PMCID: PMC1284669  PMID: 9684345
17.  Changes in Altitude Cause Unintended Insulin Delivery From Insulin Pumps 
Diabetes Care  2011;34(9):1932-1933.
OBJECTIVE
Children and adults with type 1 diabetes who receive insulin pump therapy have reported hypoglycemia during air travel. We studied the effects of atmospheric pressure on insulin pump delivery.
RESEARCH DESIGN AND METHODS
Ten insulin pumps were connected to capillary tubes. The effects of changes in ambient pressure on insulin delivery, bubble formation, bubble size, and cartridge plunger movement were analyzed.
RESULTS
During a flight (200 mmHg pressure decrease), excess insulin delivery of 0.623% of the cartridge volume occurred (P < 0.001, Student t test). In hypobaric chamber studies, bubbles developed in the insulin when the pressure decreased and displaced the insulin out of the cartridge. Pre-existing bubbles changed in size consistent with Boyle law. Cartridge plunger movement did not occur in normal flight conditions but did occur when catastrophic plane depressurization was mimicked.
CONCLUSIONS
Atmospheric pressure reduction causes predictable, unintended insulin delivery in pumps by bubble formation and expansion of existing bubbles.
doi:10.2337/dc11-0139
PMCID: PMC3161261  PMID: 21816978
18.  Facial fat grafting with a prototype injection control device 
Objective
To evaluate the initial clinical performance of a prototype injection control device (ICD) to facilitate fat grafting by injection.
Methods
An ICD, which mechanically couples the act of withdrawing the cannula with the act of depressing the plunger, was fabricated for the purpose of facial fat grafting. The action of the device results in deposition of consistent threads of fat having a volume of approximately 33 uL per cm that the cannula is withdrawn, which is slightly less than the internal volume of a 12-gauge cannula. A total of 26 patients underwent 30 procedures, and the results were subjectively evaluated using pre- and postoperative photographs, with a minimum follow-up of 4 months.
Results
The desired degree of correction was more consistent, recovery was faster, and procedural efficiency was improved when performing the procedure with the ICD compared to historical use of the manual method of injection. Minor irregularities were the only complications encountered.
Conclusion
The ICD optimally distributes fat as a uniform thread along the withdrawal tract of the cannula, thereby eliminating clumping and minimizing tissue trauma, resulting in reduced recovery time as well as more consistent and predictable clinical results. Since the ICD automates the injection process, it provides a notable and easily attainable efficiency in procedural time and minimal learning curve for the user.
doi:10.2147/CCID.S47469
PMCID: PMC3775639  PMID: 24049453
dermal fillers; liposuction; facial rejuvenation; threading
19.  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
20.  Design, Fabrication and Experimental Validation of a Novel Dry-Contact Sensor for Measuring Electroencephalography Signals without Skin Preparation 
Sensors (Basel, Switzerland)  2011;11(6):5819-5834.
In the present study, novel dry-contact sensors for measuring electro-encephalography (EEG) signals without any skin preparation are designed, fabricated by an injection molding manufacturing process and experimentally validated. Conventional wet electrodes are commonly used to measure EEG signals; they provide excellent EEG signals subject to proper skin preparation and conductive gel application. However, a series of skin preparation procedures for applying the wet electrodes is always required and usually creates trouble for users. To overcome these drawbacks, novel dry-contact EEG sensors were proposed for potential operation in the presence or absence of hair and without any skin preparation or conductive gel usage. The dry EEG sensors were designed to contact the scalp surface with 17 spring contact probes. Each probe was designed to include a probe head, plunger, spring, and barrel. The 17 probes were inserted into a flexible substrate using a one-time forming process via an established injection molding procedure. With these 17 spring contact probes, the flexible substrate allows for high geometric conformity between the sensor and the irregular scalp surface to maintain low skin-sensor interface impedance. Additionally, the flexible substrate also initiates a sensor buffer effect, eliminating pain when force is applied. The proposed dry EEG sensor was reliable in measuring EEG signals without any skin preparation or conductive gel usage, as compared with the conventional wet electrodes.
doi:10.3390/s110605819
PMCID: PMC3231409  PMID: 22163929
electroencephalography (EEG); dry electrode; conductive gels; skin-sensor interface impedance
21.  Pharmacokinetics of Lidocaine With Epinephrine Following Local Anesthesia Reversal With Phentolamine Mesylate 
Anesthesia Progress  2008;55(2):40-48.
Phentolamine mesylate accelerates recovery from oral soft tissue anesthesia in patients who have received local anesthetic injections containing a vasoconstrictor. The proposed mechanism is that phentolamine, an alpha-adrenergic antagonist, blocks the vasoconstriction associated with the epinephrine used in dental anesthetic formulations, thus enhancing the systemic absorption of the local anesthetic from the injection site. Assessments of the pharmacokinetics of lidocaine and phentolamine, and the impact of phentolamine on the pharmacokinetics of lidocaine with epinephrine were performed to characterize this potentially valuable strategy. The blood levels of phentolamine were determined following its administration intraorally and intravenously. Additionally, the effects of phentolamine mesylate on the pharmacokinetics of intraoral injections of lidocaine with epinephrine were evaluated. Sixteen subjects were enrolled in this phase 1 trial, each receiving 4 drug treatments: 1 cartridge lidocaine/epinephrine followed after 30 minutes by 1 cartridge phentolamine (1L1P), 1 cartridge phentolamine administered intravenously (1Piv), 4 cartridges lidocaine/epinephrine followed after 30 minutes by 2 cartridges phentolamine (4L2P), and 4 cartridges lidocaine/epinephrine followed by no phentolamine (4L). Pharmacokinetic parameters estimated for phentolamine, lidocaine, and epinephrine included peak plasma concentration (Cmax), time to peak plasma concentration (Tmax), area under the plasma concentration-time curve from 0 to the last time point (AUClast) or from time 0 to infinity (AUCinf), elimination half-life (t1/2), clearance (CL), and volume of distribution (Vd). The phentolamine Tmax occurred earlier following the intravenous administration of 1Piv (7 minutes than following its submucosal administration in treatment 1L1P (15 minutes) or 4L2P (11 minutes). The phentolamine t1/2, CL, and Vd values were similar for 1L1P, 1Piv, and 4L2P. The Tmax for lidocaine occurred later and the Cmax for lidocaine was slightly higher when comparing the 4L2P treatment and the 4L treatment. The phentolamine-induced delay of the lidocaine Tmax likely represents phentolamine's ability to accelerate the systemic absorption of lidocaine from oral tissues into the systemic circulation.
doi:10.2344/0003-3006(2008)55[40:POLWEF]2.0.CO;2
PMCID: PMC2424015  PMID: 18547152
Pharmacokinetics; Dental local anesthesia; Lidocaine; Phentolamine; Epinephrine
22.  Cardiovascular Alterations After Injection of 2% Lidocaine With Norepinephrine 1:50,000 (Xylestesin) in Rats 
Anesthesia Progress  2007;54(2):45-49.
The purpose of the present study is to determine the cardiovascular effects produced by intravascular injection of 2% lidocaine with 20 μg/mL of norepinephrine on systolic, diastolic, and mean arterial pressures and heart rate of rats at the following times: control period, during the injection (first 15 seconds), during the first minute, and at the end of 1, 2, 3, 4, 5, 10, 15, 20, 25, and 30 minutes after drug administration. The study was performed on 13 male Wistar rats with weights between 200 grams and 220 grams that were awake during the recording of these parameters. The dose administered was proportional to 1 cartridge of local anesthetic (1.8 mL) in an average-size human, which is equivalent to 0.51 mg/kg of lidocaine hydrochloride and 0.51 μg/kg of norepinephrine hydrochloride. The average time of injection was 15.7 seconds. The results of this study showed significant increases in systolic, diastolic, and mean arterial pressure and a noticeable decrease in heart rate. The greatest variation occurred in the systolic blood pressure. The greatest alterations occurred during injection and within the first minute following administration of the anesthetic solution. We would anticipate these changes in the parameters analyzed to be clinically significant. Thus, dentists using 2% lidocaine with norepinephrine 20 μg/mL should be very careful to avoid intravascular injection.
doi:10.2344/0003-3006(2007)54[45:CAAIOL]2.0.CO;2
PMCID: PMC1893092  PMID: 17579502
Intravascular injection; Lidocaine; Norepinephrine
23.  Effect of pre-cooling injection site on pain perception in pediatric dentistry: “A randomized clinical trial” 
Dental Research Journal  2013;10(6):790-794.
Background:
Injection of local anesthesia is one of the most important reasons for development of avoidance behavior in children. Efforts have been performed to decrease pain perception of injection. The present research evaluated the effect of cooling the injection site on pain perception before infiltration of local anesthetics.
Materials and Methods:
A prospective single-blind crossover clinical trial was used to investigate pain perception in 50 healthy pediatric patients who needed bilateral buccal infiltration of local anesthetics for dental treatment. They received a topical anesthetic agent (Benzocaine) on one side (control) for 1 min and topical anesthetic agent plus one minute of ice pack on the other side (trial) prior to the injection. A dentist blind to the study assessed the patients’ reaction during injection. Wilcoxon and Mann-Whitney U tests were used for statistical analysis. Statistical significance was defined at P < 0.05.
Results:
The means of sound, eye, and motor scales (SEM) were 4.06 ± 1.32 and 5.44 ± 1.79 for the study and control groups, respectively. The means of visual analogue scales (VAS) for the study and control groups were 42.20 ± 12.70 and 58.40 ± 16.83, respectively; with statistically significant differences between the two groups (P < 0.05).
Conclusion:
Cooling the injection site before infiltration of local anesthetics in the buccal mucosa for 1 min, reduced pain perceived by pediatric patients.
PMCID: PMC3872632  PMID: 24379869
Cooling; local injection; pain perception
24.  Suprapubic Bladder Aspiration in Neonates 
Canadian Family Physician  1987;33:2099-2100.
Suprapubic bladder aspiration in neonates is a simple, safe, and useful technique for collection of sterile urine. The procedure can be performed in the hospital or office. Neither sedation nor local anesthetic is required. Suprapubic bladder aspiration of urine is the preferred method of collecting urine for culture in septic neonates. The technique is also indicated to verify urinary tract infection in neonates. Suprapubic bladder aspiration is contraindicated in the presence of abdominal distension or an empty bladder. Carefully and properly performed, the risk of complications should be negligible, and the success rate in obtaining urine is 90%.
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PMCID: PMC2218649  PMID: 21263980
suprapubic bladder aspiration; neonates
25.  The Role of Needle Purging in Reducing Transfer of Microorganisms From Local Anesthetic Cartridge Diaphragms 
Anesthesia Progress  1985;32(4):157-160.
The literature is reviewed to demonstrate the significant amount of contamination on the external surface of the anesthetic cartridge diaphragm. Current methods of cartridge diaphragm decontamination to prevent injection of pathogens are discussed. A series of bacteriologic tests were conducted to determine the probability of transfer of pathogens from the diaphragm surface through the needle lumen of three different sizes to the deposition site. Results of needle purging suggest that a significant reduction in the transfer of microorganisms is possible using this technique.
PMCID: PMC2148537  PMID: 3907421

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