Intradermal Anesthesia Research Articles

The effect of escalating heat stimulation on top of anesthetized skin

The relationship between itch and heat pain has been vastly explored. A 70-year-old study, showed the development of paradoxical itch following heat stimulation of anesthetized skin. The aim of this study was to re-evaluate, with more modern technologies and systematic approaches, this paradoxical itch effect. Escalating heat stimuli were applied to the local anesthetized skin of 19 healthy subjects, itch, and pain intensities were continuously assessed during the stimulation. As expected, pain sensation was significantly reduced by local intradermal anesthesia, however, no paradoxical itch sensations were observed for any of the stimulation temperatures.

Local anesthesia before intravenous cannula insertion: Recommendations for registered nurses in practice

Objective: The purposes of this project were to educate registered nurses of the intradermal, pretreatment procedure; provide education on the hospital’s current IV therapy pretreatment policy; and increase the usage of intradermal, local anesthesia for cannulation for adult patients’ comfort level.Methods: A mixed method of nonexperimental descriptive pre- and post-survey was used. The data was collected from 48 registered nurses’ pre- and post-surveys indicating descriptive analysis. The descriptive analysis identified barriers as to why registered nurses were not using pretreatment prior to IV insertion. Results: The results revealed the majority of the participants (83%) were not aware of the hospital’s IV pretreatment policy of intradermal anesthesia with Lidocaine before IV insertion prior to the DNP project. Evidence indicated inconsistency in the use of pain management strategies during these procedures. The conclusions of this project provided an important overview of the barriers to change in clinical practice for registered nurses with IV skills.Conclusions: An improvement project educational program, such as an educational video on how to preform intradermal pretreatment to an IV site prior to IV insertion and utilization of a manikin IV arm for simulation practice, was developed and recommended to a nursing IV therapy practice for registered nurses. Local anesthetic, such as intradermal, should become standard practice for registered nurses regarding pretreatment for pain control prior to intravenous insertion.

The effects of preferential A- and C-fibre blocks and T-type calcium channel antagonist on detection of low-force monofilaments in healthy human participants.

BackgroundA myriad of studies have argued that tactile sensibility is underpinned exclusively by large myelinated mechanoreceptors. However, the functional significance of their slow-conducting counterparts, termed C-low threshold mechanoreceptors (C-LTMRs), remains largely unexplored. We recently showed the emergence of brush- and vibration-evoked allodynia in human hairy and glabrous skin during background muscle pain. The allodynia persisted following the preferential blockade of myelinated fibres but was abolished by the preferential blockade of cutaneous C fibres, thereby suggesting a pathway involving hairy skin C-LTMRs and their functional counterparts in glabrous skin in this phenomenon. In the present study, we tested the effects of preferential A- and C-fibre conduction blocks and pharmacological blockade of T-type calcium channel Cav3.2 (expressed selectively on small-fibre LTMRs) on monofilament detection thresholds in healthy participants by compression, low-dose intradermal anaesthesia (xylocaine 0.25 %) and selective T-channel antagonist, TTA-A2.ResultsWe found that all participants could detect monofilament contacts (as low as 1.6 mN) within the innocuous tactile range regardless of the preferential blockade of myelinated fibres. Furthermore, during the compression block no subject reported a switch in modality from touch to pain. That is, the low-force monofilament contacts were always perceived as non-painful. However, there was a small but significant elevation of monofilament thresholds (~2 mN) in the glabrous skin following the compression block. Importantly, no differences were found in the thresholds across hairy and glabrous regions while the myelinated fibres were conducting or not. The preferential blockade of C fibres in the glabrous skin (with myelinated fibres intact) also resulted in a small but significant elevation of tactile thresholds. Furthermore, the use of T-channel blocker in the glabrous skin during compression block of myelinated fibres resulted in complete abolition of monofilament sensibility within the innocuous tactile range (tested up to ~20 mN).ConclusionsThese observations suggest that C-LTMRs need not be regarded as a redundant tactile system, but appear to complement normal large-myelinated-fibre tactile function. Convergent findings in glabrous and hairy skin lend support for an underlying system of innocuous mechanoreception with Cav3.2-expressing unmyelinated fibres.

Mechanical allodynia in human glabrous skin mediated by low-threshold cutaneous mechanoreceptors with unmyelinated fibres

We recently showed that C-tactile fibres (CTs) in human hairy skin (anterior leg) mediate crossover between innocuous touch and noxious touch, i.e. mechanical allodynia. Although there is no evidence for existence of a phenotypically identical class of CTs in human glabrous skin, the 'qualia' of affective stimuli are comparable across skin types. In 42 healthy subjects, muscle pain was induced by infusing hypertonic saline (5 %) into flexor carpi ulnaris muscle. Concurrently, sinusoidal vibration (200 Hz-200 μm) was applied to glabrous skin of little finger. The neural substrate of allodynia was determined by employing conduction blocks of myelinated (ulnar nerve compression) and unmyelinated (low-dose intra-dermal anaesthesia) fibres. In order to compare the expression of allodynia across spinal segments and skin types, vibration was also applied to glabrous skin of index finger and hairy skin of dorsal forearm. In addition, high-precision brushing stimuli were applied at speeds of 1.0 and 3.0 cm s(-1) to digital glabrous skin with absent myelinated fibres. During muscle pain, vibration caused a significant and reproducible increase in pain (allodynia). This effect persisted during blockade of myelinated fibres, but was abolished by inactivation of unmyelinated cutaneous fibres. The vibration-evoked effects were found to be comparable across spinal segments and skin types. Furthermore, brushing produced a near-identical expression of C-fibre-mediated allodynia. Prior to induction and upon cessation of muscle pain, vibration and brushing were reported as non-painful. Based on these results, we postulate that a functional homologue of the CTs (hairy skin) mediates allodynia in human glabrous skin.

An investigation into the peripheral substrates involved in the tactile modulation of cutaneous pain with emphasis on the C-tactile fibres

We recently demonstrated the emergence of touch-evoked pain (allodynia) during innocuous tactile stimulation of the skin overlying a painful muscle. This effect appeared to depend on a class of low-threshold unmyelinated mechanoafferents, termed C-tactile fibres (CT). In this study, we investigated the peripheral neurocircuitry of allodynia when pain originates in the skin. Psychophysical observations were carried out in 28 healthy subjects. Cutaneous pain was induced by infusing hypertonic saline (HS: 5 %) into the hairy skin overlying tibialis anterior muscle. An innocuous tactile stimulus (sinusoidal vibration: 200 Hz-200 μm) was concurrently applied to the hairy skin ~90 mm distal to the HS-infusion site. The contribution of different fibre classes to allodynia was determined by employing conduction blocks of myelinated (sciatic nerve compression) and unmyelinated (intradermal anaesthesia, Xylocaine 0.25 %) fibres. In absence of background nociceptive input, vibration was reported as non-painful. During cutaneous pain, vibration evoked a significant and reproducible increase in the overall pain intensity (allodynia). The blockade of myelinated fibres abolished the vibration sense, but the vibration-evoked allodynia persisted. Conversely, the blockade of unmyelinated cutaneous fibres abolished the allodynia (while the myelinated fibres were conducting or not). On the basis of these findings, in addition to our earlier work, we conclude that the allodynic effect of CT-fibre activation is not limited to nociceptive input arising from the muscle, but can be equally realized when pain originates in the skin. These results denote a broader role of CTs in pain modulation.

C-tactile Fibers Contribute to Cutaneous Allodynia After Eccentric Exercise

We recently showed that during acute muscle pain, C-tactile (CT) fibers mediate allodynia in healthy human subjects. In this study, we pursued the following questions: Do CTs contribute to allodynia observed in delayed onset muscle soreness (DOMS)? Is CT-mediated allodynia reproducible in a clinical pain state? In 30 healthy subjects, DOMS was induced in anterior compartment muscles of the leg by repeated eccentric contractions. DOMS was confirmed by mapping the emergence of tender points (decreased pressure pain thresholds). Furthermore, we measured pressure pain thresholds in a clinical subject who presented with activity-triggered heel pain but no resting pain. Cutaneous vibration (sinusoidal; 200 Hz–200 μm)—an otherwise innocuous stimulus—was applied to anterolateral leg before exercise, during DOMS, and following recovery from DOMS. The peripheral origin of allodynia was determined by employing conduction blocks of unmyelinated (intradermal anesthesia) and myelinated (nerve compression) fibers. In DOMS state, there was no resting pain, but vibration reproducibly evoked pain (allodynia). The blockade of cutaneous C fibers abolished this effect, whereas it persisted during blockade of myelinated fibers. In the clinical subject, without exposure to eccentric exercise, vibration (and brushing) produced a cognate expression of CT-mediated allodynia. These observations attest to a broader role of CTs in pain processing. PerspectiveThis is the first study to demonstrate the contribution of CT fibers to mechanical allodynia in exercise-induced as well as pathological pain states. These findings are of clinical significance, given the crippling effect of sensory impairments on the performance of competing athletes and patients with chronic pain and neurological disorders.

Effect of intradermal anaesthesia on success rate and pain of intravenous cannulation: a randomized non-blind crossover study

Intravenous cannulation is a commonly performed procedure. This study aimed to determine whether the success rate and pain of intravenous cannulation is affected by prior injection of intradermal lidocaine. Intravenous cannulation was performed twice in 45 healthy volunteers. Intradermal lidocaine was administered prior to one of these cannulations. The outcome measures were success or failure of cannulation, and pain of cannulation, measured with a 100 mm visual analogue pain scale. The success rate of intravenous cannulation with and without prior intradermal lidocaine was 54% and 76%, respectively. The difference was 22.0% (95% CI 1.5-27.8%; P = 0.03). Log-linear analysis for three-way interaction between the variables (outcome, vascular condition and use of lidocaine) showed a significant influence of vascular condition on outcome (G(2) 24.6, P < 0.001). The mean (SD) pain scores in the control and intervention group were 34.8 (21.0) and 13.6 (13.2) mm, respectively. The difference between the mean pain scores was 21.2 mm (95% CI 15.1-27.3 mm). In conclusion, the success rate of intravenous cannulation may be reduced with the use of intradermal lidocaine, but success rate is primarily dependent on vascular condition. Intradermal lidocaine achieves a clinically significant reduction in the pain of intravenous cannulation.

Allodynia mediated by C‐tactile afferents in human hairy skin

We recently showed a contribution of low-threshold cutaneous mechanoreceptors to vibration-evoked changes in the perception of muscle pain. Neutral-touch stimulation (vibration) of the hairy skin during underlying muscle pain evoked an overall increase in pain intensity, i.e. allodynia. This effect appeared to be dependent upon cutaneous afferents, as allodynia was abolished by intradermal anaesthesia. However, it remains unclear whether allodynia results from activation of a single class of cutaneous afferents or the convergence of inputs from multiple classes. Intriguingly, no existing human study has examined the contribution of C-tactile (CT) afferents to allodynia. Detailed psychophysical observations were made in 29 healthy subjects (18 males and 11 females). Sustained muscle pain was induced by infusing hypertonic saline (HS: 5%) into tibialis anterior muscle (TA). Sinusoidal vibration (200 Hz–200 μm) was applied to the hairy skin overlying TA. Pain ratings were recorded using a visual analogue scale (VAS). In order to evaluate the role of myelinated and unmyelinated cutaneous afferents in the expression of vibration-evoked allodynia, compression block of the sciatic nerve, and low-dose intradermal anaesthesia (Xylocaine 0.25%) were used, respectively. In addition, the modulation of muscle pain by gentle brushing (1.0 and 3.0 cm s(−1))--known to excite CT fibres--was examined. Brushing stimuli were applied to the hairy skin with all fibres intact and following the blockade of myelinated afferents. During tonic muscle pain (VAS 4–6), vibration evoked a significant and reproducible increase in muscle pain (allodynia) that persisted following compression of myelinated afferents. During compression block, the sense of vibration was abolished, but the vibration-evoked allodynia persisted. In contrast, selective anaesthesia of unmyelinated cutaneous afferents abolished the allodynia, whereas the percept of vibration remained unaffected. Furthermore, allodynia was preserved in the adjacent non-anaesthetized skin. Conformingly, gentle brushing produced allodynia (at both brushing speeds) that persisted during the blockade of myelinated afferents. Prior to the induction and following cessation of muscle pain, all subjects reported vibration and brushing as non-painful (VAS = 0). These results demonstrate that CT fibres in hairy skin mediate allodynia, and that CT-mediated inputs have a pluripotent central effect.

In vivo assessment of pigmentary and vascular compartments changes in UVA exposed skin by reflectance‐mode confocal microscopy

Exposure of the skin to ultraviolet A (UVA) results in various biological responses, skin-colour changes being among the major ones. Although intense research has been performed on UVA-induced pigmentation and vascular changes, the process of skin-colour changes after UVA irradiation remains unclear. For a better understanding of the UVA tanning mechanism, we here performed a human study in 27 healthy volunteers with skin phototype (SPT) II to VI. After a single UVA exposure to inner forearm, the skin sites were imaged using reflectance-mode confocal microscopy (RCM), for analysis of melanin and vascular changes. Punch biopsies were also taken from the UVA-exposed or non-exposed sites for histological examination. Skin sections were stained with Fontana-Masson and evaluated by a sensitive tyrosinase assay for comparison with RCM images. Furthermore, the effect of blood flow on skin-colour changes was evaluated visually after administration of an intradermal anesthesia of lidocaine with or without epinephrine. Our RCM analysis showed dendritic melanocytes and a different melanin distribution in the epidermal layer, clearly visible 1 week after the UVA exposure in subjects of SPT V which were supported by histological examination. However, no melanin distribution pattern changes were apparent immediately after the exposure, while RCM images showed accelerated capillary flow patterns. The restriction of this UVA induced-accelerated blood flow by epinephrine inhibited partially or completely the immediate pigment darkening and delayed tanning. These in vivo studies confirmed that vascular change is an important factor for the development of the immediate pigment darkening and delayed tanning.

Comparison of Bacteriostatic Normal Saline and Lidocaine Used as Intradermal Anesthesia for the Placement of Intravenous Lines

Pain with intravenous (IV) insertion is a common fear for preoperative patients. As perianesthesia nurses, we take the necessary measures to minimize the discomfort and anxiety of our patients. Several research studies have found the use of bacteriostatic normal saline (BNS) to produce a less painful, yet equally effective, safer, and less expensive alternative method for intradermal anesthesia. The purpose of this study was to determine whether a difference existed in pain with intradermal injection and pain with venipuncture when intradermal anesthesia was used. Using an experimental design, 221 participants were randomly assigned by lottery convenience sampling into three groups: lidocaine, BNS, and no local anesthesia. Patients were asked to quantify their pain/discomfort level after the intradermal injection and IV insertion using a modified visual analog scale. Significant findings (P = < .05) indicated that BNS was less painful on injection, and both BNS and lidocaine were effective as local anesthetics for IV insertion. This study helped perianesthesia nurses and patients in determining which method of IV insertion is more effective and reasonably acceptable to ensure patient comfort, satisfaction, and positive outcomes.

Intradermal ketorolac for reduction of epidural back pain

Between 30 and 45% of all parturients receiving epidural laboring analgesia complain of postpartum back pain. Although long-term or chronic back pain has been reported, our study focuses on acute or short-term back pain that resolves within 72 h. The purpose of this randomized double-blind, placebo-controlled investigation was to determine if a ketorolac/lidocaine intradermal anesthesia combination could decrease post-epidural back pain. A total of 81 non-complicated parturients requesting epidural analgesia were approached for inclusion and randomized to receive either 3 mL of 1% lidocaine (control group) or 3 mL of 1% lidocaine with 6 mg ketorolac (experimental group) for dermal anesthesia. A 0–10 verbal numeric scale was used to assess pain at rest and with activity at 24 and 72 h. Demographics, mode of delivery, and duration of labor were noted. A χ2 test was used to analyse frequency data and a Student's t-test and generalized estimation equation were used to analyze ordinal and interval data. Demographics, mode of delivery and length of labor were similar between groups. Significantly lower verbal numeric scores were noted in the experimental group at the 24-h active measurements after vaginal delivery and at 24 and 72 h for both active and resting measurements after cesarean delivery. Based on these findings it can be recommended that intradermal ketorolac given at the time of epidural catheter placement may result in a reduction in post-epidural back pain in the parturient, especially in the event of cesarean delivery.

Saline with Benzyl Alcohol as Intradermal Anesthesia for Intravenous Line Placement in Children

Saline with Benzyl Alcohol as Intradermal Anesthesia for Intravenous Line Placement in Children

Effect of temperature and pH adjustment of bupivacaine for intradermal anesthesia

To determine the effects of warming and buffering of 0.5% bupivacaine on the pain associated with intradermal injection and the time of onset of anesthesia, 40 adult volunteers were entered into a randomized, double-blind study conducted at a community teaching hospital. The three-part study compared room temperature (20°) bupivacaine buffered to a pH of 7.1 with the following solutions: buffered bupivacaine warmed to 37°C, unbuffered bupivacaine at room temperature, and unbuffered bupivacaine warmed to 37°C. The same crossover protocol was followed for each part of the study. Subjects received 0.5-mL intradermal injections through 27-gauge needles over 30 seconds, one study solution in each forearm. Immediately after each injection, pain was assessed using a 100-mm visual analog pain scale. The time of onset of anesthesia (loss of intradermal sensation to pinprick) was measured by stopwatch. The mean perceived pain score for the warm buffered bupivacaine (51 mm) was significantly lower than for the room temperature buffered solution (63 mm, P = .003). Similarly, there was a statistical difference between the room temperature buffered and unbuffered solutions (65 v 78 mm, P < .001). The differences in mean pain scores for the room temperature buffered bupivacaine, compared with the other three solutions, suggest that warming and buffering have an additive effect. In this model, the latency of action of bupivacaine was not affected by alkalinization. However, warming bupivacaine to 37°C reduced the time of onset to intradermal anesthesia by 12.1 seconds (95% confidence interval, 0.6 to 23.6). These results suggest that warming is more effective than buffering to reduce the pain of infiltration of bupivacaine and the time of onset of intradermal anesthesia.

INTRADERMAL ANESTHESIA AND COMPARISON OF INTRAVENOUS CATHETER GAUGE

A double-blinded randomized prospective study was performed to determine whether alkalinization of lidocaine decreases the pain of intradermal injection and if a larger intravenous catheter (16 gauge) causes more discomfort on insertion than a smaller (20 gauge) catheter when intradermal anesthesia has been used. In a random manner, 100 patients received skin wheals with commercially prepared lidocaine or lidocaine with the addition of sodium bicarbonate before the insertion of a 16- or 20-gauge intravenous catheter. Visual analogue pain scores were obtained after the skin wheal was placed and after the intravenous catheter was inserted. There was no statistically significant difference in pain scores between the two local anesthetic solutions. However, the catheter insertions pain scores were slightly, but statistically significantly larger in the 16-gauge group regardless of local anesthetic solution used. The addition of sodium bicarbonate to commercially prepared lidocaine does not decrease the pain associated with an intradermal skin wheal. There is a slight increase in patient discomfort upon insertion of a large-bore intravenous catheter, even with the prior use of local anesthetic.

Local anaesthetics imidazole and calcium

Experimenting with corneal and intradermal anaesthesia on guinea-pigs, the following were found: 1 — an increment in the local anaesthetic activity of cocaine, procaine and lidocaine, by intraperitoneal administration of Imidazole, 2 — an antagonistic action of calcium ions with the Imidazole effects, and 3 — that Imidazole is not shown to exert any local anaesthetic activity.

Effect of Some Vasoconstrictors on Intradermal Anesthesia

Effect of Some Vasoconstrictors on Intradermal Anesthesia

The pharmacology and toxicology of mepivacaine, a new local anesthetic

The local anesthetic activity, toxicity, and irritancy of mepivacaine HCl 1 (1-methyl-2′,6′-pipecoloxylidide hydrochloride) and a solution (solution B) containing 2.0% mepivacaine HCl and 1:20,000 levo-nordefrin (levo-2,4-dihydroxyphenyl-3-hydroxy-2-isopropylamine 2) have been studied by various methods. By the intracutaneous wheal test in guinea pigs mepivacaine HCl is 2.5 times more active than procaine HCl. The addition of levo-nordefrin produced a slight increase in the local anesthetic activity of the solution. Solution B was found as active as a solution of 2.0% lidocaine + epinephrine 1:100,000 by the same route of administration ( dilution test). At the 2.0% concentration level in solutions containing epinephrine 1:100,000 the duration of mepivacaine intradermal anesthesia was approximately 25% longer than that produced by lidocaine. Mepivacaine HCl was found to be as active as cocaine HCl by topical application to the rabbit eye. The topical TAC 5 was 0.18%. At 2, 3, 4, and 8% concentrations, mepivacaine HCl injected intraspinally in rabbits produced anesthesia lasting from 17 to 115 minutes (urethral anesthesia). The degree of intraspinal irritancy appears to be somewhat lower than that of lidocaine. By intravenous injection the following LD 50 values for mepivacaine HCl in mice, rabbits, and guinea pigs were obtained: 32±2, 22±2, and 20±1.4 mg/kg, respectively. Mepivacaine is approximately twice as toxic as procaine HCl and 40% less toxic than lidocaine HCl in mice. The subcutaneous LD 50 values were: 260±22, 110±11, and 94±10 mg/kg for mice, rabbits, and guinea pigs, respectively. Solution B and a 3% solution of mepivacaine HCl without levo-nordefrin (solution A) were well tolerated by monkeys and rats when injected intramuscularly or intravenously in single daily doses eighteen times in 21 days. No significant changes were observed in the body weights, blood counts, urinalyses, or blood pressures of the medicated animals at the end of the medication period. No changes attributable to medication with mepivacaine were observed at the autopsies of the medicated animals. By the trypan blue test the threshold irritant concentration 4 of mepivacaine HCl was 3.3%. That of lidocaine HCl, which was tested in parallel, was 1.9%. Lidocaine HCl is therefore approximately 70% more irritant than mepivacaine HCl. Applied topically on the rabbit eye, mepivacaine HCl and lidocaine HCl were well tolerated in concentrations up to 20%. Solution A and solution B produced a slight, transient inflammatory reaction when injected intramuscularly into rabbits in 1.0-cc doses. No lesions at the injection sites were observed at 7 days after the injection. In summary, mepivacaine HCl, which is 2.5 times more active than procaine HCl is only 25% more irritating and is well tolerated locally as well as systemically on repeated subcutaneous or intramuscular administration.

Intradermal anesthesia in first-stage labor.

Intradermal anesthesia in first-stage labor.

Intradermal Anesthesia for Labor Pains

Intradermal Anesthesia for Labor Pains