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Safety, tolerability, and efficacy of iontophoresis with lidocaine for dermal anesthesia in ED pediatric patients
RESEARCH
Safety, Tolerability, and Efficacy of Iontophoresis With Lidocaine for Dermal Anesthesia in ED Pediatric Patients Authors: Alyce A. Schultz, RN, PhD, Tania D. Strout, RN, BSN, Pam Jordan, RN, BSN, and Barry Worthing, RN, BSN, Portland, Me
Alyce A. Schultz is Nurse Researcher; Tania D. Strout, Maine ENA, is Research Nurse Coordinator, Emergency Department; Pam Jordan, Maine ENA, is Staff Nurse, Emergency Department; and Barry Worthing, Maine ENA, is Staff Nurse, Emergency Department, Maine Medical Center, Portland, Me. Funded in part by a combined grant from Sigma Theta Tau International and the ENA Foundation. For reprints, write: Alyce A. Schultz, RN, PhD, 20 Groveside Rd, Portland, ME 04102; E-mail: [email protected]. J Emerg Nurs 2002;28:289-96. Copyright © 2002 by the Emergency Nurses Association. 0099-1767/2002 $35.00 +0 18/1/125791 doi:10.1067/men.2002.125791
Introduction: This study examined the safety, tolerability, and
efficacy of iontophoresis with 30 mA of lidocaine for dermal anesthesia in children younger than 84 months in the emergency department and the usefulness of a modified version of the Pre-Verbal, Early verbal, Pediatric Pain Scale (M-PEPPS). Methods: Three expert nurses completed the protocol for ionto-
phoresis and inserted an intravenous catheter. Parents scored pain by using the 10-cm Visual Analogue Scale, nurses used the M-PEPPS, and children, if able, self-reported pain during the procedure and at needle stick. Results: Serum lidocaine levels were within the normal laborato-
ry reference range. Adverse effects were minor and disappeared prior to discharge from the emergency department. Eighty-five percent of the children had M-PEPPS scores ≤6 during the iontophoresis procedure; 42% had scores of ≤6 at needle stick. Eighty-two percent of the parents marked the VAS as ≤30 during the procedure; 65% indicated scores of ≤30 at needle stick. Four children self-reported “a lot of pain” at needle stick. Although low to moderate, M-PEPPS scores and parental pain ratings were significantly correlated at both points in time. Discussion: Iontophoresis with lidocaine is safe for use in young
children. It does not create any long-term untoward effects and is quite well tolerated. It is not clear if the higher pain scores at needle stick reflect anxiety and fear of a needle or a painful experience.
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T
he anxiety and pain associated with venous access in the pediatric population is experienced daily by children admitted for emergency care (and their parents). Approximately 10% of the admissions to the Maine Medical Center level I emergency department are children between the ages of 1 and 7 years, and a significant number of these children require peripheral intravenous (PIV) therapy during their ED stay. In acute care settings, particularly in emergency departments, it is imperative that procedures be done in a rapid, sequential order. PIV cannulation is usually painful for the child; the pain and anxiety associated with pediatric cannulation often impede the rapidity and success of establishing PIV access. Prilocaine (EMLA) and iontophoresis of lidocaine are alternative, noninvasive treatments to intracutaneous injection of lidocaine or buffered lidocaine for obtaining topical anesthesia prior to cannulation. Prilocaine is a cream applied directly to the epidermis and covered with a semiocclusive dressing. The cream must be in place for at least 60 minutes prior to cannulation to produce adequate dermal anesthesia.1,2 In the emergency department, venous access is usually needed in less than 1 hour, and thus the use of EMLA as a topical anesthetic agent is not feasible. Background
Iontophoresis for dermal anesthesia is the introduction of water-soluble, positively charged lidocaine hydrochloride and epinephrine into the skin by a small external electric current. The transdermal iontophoresis is accomplished with use of a small, battery-operated unit with a positive and negative connection to one medicated and one dispersive electrode. The electric current, set from 0.0 to 4.0 mA, causes the medication to flow through the skin beneath the electrode, through the interstitial tissue, and back through the skin to the other electrode. The exact mechanism for the ionic transport is unclear.3 Lidocaine stabilizes the neuronal membrane, inhibiting the ionic movements required for the conduction of painful stimuli to the brain, and thus provides local anesthesia. The half-life for intravenous administration is 11⁄2 to 2 hours. Epinephrine, with its vasconstrictive property, increases the duration and depth of anesthesia and decreases the departure of lidocaine from the site. Epinephrine may
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increase the possibility of systemic absorption of lidocaine. Thirty milliamperes, the dosage used in this study, reportedly produces dermal anesthesia to an average depth of 8.4 mm, which is adequate for intravenous cannulation.4 Depending on the dosage, anesthesia is usually achieved in less than 15 minutes.5-7 Whereas numerous studies have been reported on the safety and efficacy of EMLA as a topical anesthetic agent prior to intravenous cannulation,1,2,8-14 limited studies have been published on the use of an iontophoresis system for dermal anesthesia in a pediatric population.6,7,15 No studies were found that addressed the safety of iontophoresis with lidocaine for dermal anesthesia in a pediatric population, regardless of age. Efficacy studies have only been reported for children older than 7 years,6,7 yet the iontophoresis procedure for dermal anesthesia is currently marketed for all age groups. Purpose
The primary purpose of this study was to examine the safety, tolerability, and efficacy of iontophoresis with lidocaine for dermal anesthesia prior to venous access in children between the ages of 12 and 84 months who come to the emergency department for treatment. The primary research questions was: Is iontophoresis with lidocaine effective for reducing the pain of venipuncture? The specific aims were to examine the following: (1) evidence of lidocaine in the blood following iontophoresis with 30 mA of lidocaine hydrochloride 2% with 1/100,000 epinephrine in young children; (2) adverse effects of iontophoresis with lidocaine in young children; (3) duration of the adverse effects; (4) treatment needs for resolution of adverse effects; and (5) the usefulness, reliability, and validity of a modified version of the Pre-verbal, Early Verbal Pediatric Pain Scale (M-PEPPS)16 for measuring procedural pain in young children. Methodology
The study had a prospective, descriptive design and was conducted in an emergency department that has 50,000 admissions annually, including approximately 5000 pediatric admissions. A convenience sample of children between the
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ages of 12 and 84 months was obtained. Sample size discussions with a statistician determined that 40 children would be adequate to establish the efficacy of iontophoresis in reducing the pain of venipuncture (personal communication, Dr Douglas Thompson, January 5, 2000). Inclusion criteria, in addition to age, were English-speaking parents and PIV anticipated within an hour. Children diagnosed with mental retardation, unstable vital signs, a rash, skin break, inflammation or scarring in the area of the selected venous access or electrode sites, an indwelling electrical device such as a pacemaker, a lidocaine allergy, or in need of emergent PIV were excluded. The parents of children who met the study criteria were approached by one of the primary investigators for consent after a physician had written the orders for PIV cannulation and iontophoresis. Following consent, the investigator selected the most appropriate site for cannulation. Distraction, including having parents read stories, playing with kaleidoscopes, singing, and coloring, was used prior to and during the iontophoresis procedure. The protocol for the iontophoresis procedure followed the recommendations of the manufacturer, IOMED, Inc. One milliliter of lidocaine 2% with 1:100,000 epinephrine was added to the drug electrode. This electrode was placed over the identified cannulation site and the ground electrode was placed on a major muscle of the child or the parent, at least 6 inches away from the drug electrode site (Figure 1). A Phoresor II machine, PM850, was used to give the treatment. The Phoresor II can be programmed to shut off automatically after the selected dose is attained. Safety checks, error messages, treatment time calculation, and shut-off are performed automatically. There is also a built-in option for manual shut-off if needed.4 The treatment was started at 1.0 mA and slowly increased when children did not report any tactile or tingling sensations at the cannulation site. All subjects who completed the study received a 30-mA dose of 2% lidocaine with 1:100,000 epinephrine. The average time for the procedure was 20 minutes, with a range from 10 to 45 minutes. The average time from the completion of the iontophoresis procedure to cannulation was 4.4 minutes, with a range from less than a minute to 14 minutes. The investigators stayed with the child throughout the procedure. Any adverse effect that was noticed or reported during the procedure was recorded.
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FIGURE 1
Iontophoresis Procedure: Ground electrode on large muscle with medication electrode on the hand.
Pain was assessed immediately prior to the start of the iontophoresis procedure, at 5 minutes after the start of the iontophoresis, at the conclusion of iontophoresis, and at the time of the needle stick for cannulation by the child’s primary nurse who was not a member of the research team. The primary nurse assessed pain by using the M-PEPPS and also asked the child, if he or she was able, to self-report pain using a 3-point ordinal scale, the standard pain assessment scale at the time of the study. Parents were asked to record their perceptions of their child’s pain on a 10-cm Visual Analogue Scale (VAS), the standard pain scale used with adults. All ED staff were oriented to the study. Staff nurses were educated on use of the M-PEPPS, the ordinal selfreport scale for children able to verbalize pain, and the VAS. The educational program included didactic materials and videotaped vignettes produced during the initial evaluation of the PEPPS. Interrater reliability of ≥.85 for the PEPPS among staff was established. Outcomes measures
SAFETY
Lidocaine levels in the plasma evaluated safety of the procedure. Blood samples were obtained immediately following
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Parameter
Facial
0
1
Relaxed facial expression
Cry (audible/ No cry visual) Consolability/ Pleasant, well state of integrated restfulness
Whimpering, groaning Distractible, easy to console, intermittent fussiness
2
Grimace, brows drawn together; eyes partially closed, squinting Intermittent crying
3
Sustained crying
Able to console, distract with difficulty, intermittent restlessness, irritability Body Posture Body at rest, Clenched fists, Localization with Intermittent or susrelaxed positioning curled toes and/or extension or flexion tained movement reaching for, touch- or stiff and nonmoving with or without ing wound or area rigidity Sociability Responds to voice With effort, responds and/or touch, makes to voice and/or touch, eye contact and/or makes eye contact but smiles, easy to obtain difficult to obtain or or maintain; sleeping maintain
4
Severe grimace; brows lowered, tightly drawn together; eyes tightly closed Screaming Unable to console, restlessness, sustained movement Sustained arching, flailing, thrashing and/or kicking Absent eye contact, no response to voice and/or touch
FIGURE 2
Modified Preverbal, Early Verbal Pediatric Pain Scale (M-PEPPS). (The authors are very interested in feedback on the use of this scale; please contact the authors for future use.)
PIV cannulation. Lidocaine assays, using fluorescencepolarization immunoassay, with an assay sensitivity of >0.1 µg/mL, were completed within 1 hour after arriving in the laboratory. Lidocaine values of less than 1.5 µg/mL are considered within normal limits in our laboratory. TOLERABILITY
Tolerability was evaluated by assessing and recording adverse effects and pain during the iontophoresis procedure. All skin changes, including tingling along the path of the electric current and redness, blanching, hives, itching, and/or blistering at the site of an electrode, were noted during or after the procedure and at the time of discharge from the emergency department. The primary nurses and the parents and child, if able, assessed pain prior to and during the procedure. Primary nurses assessed pain using a modified version of the PEPPS.16 The modified version (M-PEPPS) eliminates the categories of heart rate and sucking/feeding (Figure 2). Scoring in the modified scale can range from 0 to 20. Scores ≤6 are considered indicative of mild to no pain. Reevaluation of the original psychometric data for the M-PEPPS shows interrater reliability among the 4 original assessors
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for these 5 categories ranging from 0.87 to 0.94 compared with a range of 0.90 to 0.96, and intra-rater reliability ranging from 0.94 to 0.96 compared with 0.96 to 0.98 in the original evaluation. Internal consistency for the modified scale, as measured by Cronbach’s α, increased from .89 to .94. In the original testing, the 2 eliminated categories, sucking/feeding and heart rate, had low item to total scale correlation. Early construct validity was supported in the original testing by comparing changes in pre- and postmedication scores; pain scores prior to treatment averaged 12.0, ± 4.35, decreasing to 2.39 ± 3.8 following treatment (P < .001) (unpublished data, Schultz, 1999). One or both parents were asked to simultaneously and independently assess the child’s pain, using a 10-cm VAS. The VAS is the most common pain scale used in emergency departments and has been shown to correlate highly with the 0 to 10 pain scale.17 Children, if able, were asked by their primary nurses to describe their pain on an ordinal scale as “no hurt,” “a little hurt,” or “a lot of hurt.” EFFICACY
Efficacy of iontophoresis with lidocaine as a dermal anesthetic was assessed by pain measurements at the time of the
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needle stick. Primary nurses used the M-PEPPS, parents used the VAS, and children, if able, described their pain on an ordinal scale.
TABLE 1
Demographics Variable
Results
Informed consent was obtained from 40 parents. No children were able to give written assent, but all were present during the explanation of the study. Only one parent refused to participate in the study. Thirty-eight patients, 19 boys and 19 girls, completed the study. Their ages ranged from 12 to 83 months, with a mean of 43 months, ± 20.4, and a median of 41 months. Of the two who did not complete the study, one child could not be distracted enough to begin the iontophoresis procedure and one was unable to be distracted long enough to complete the iontophoresis. More than half of the children were admitted to the emergency department for fever, dehydration, or vomiting. Thirty of 38 PIVs were placed in the dorsum of the hand (Table 1). SAFETY
Serum lidocaine levels were within normal laboratory reference range of less than 1.5 µg/mL for the 23 samples that could be drawn within 30 minutes following cannulation. Lidocaine levels ranged from <0.2 to 1.0 µg/mL for 22 of the samples. One sample had no evidence of any lidocaine. TOLERABILITY
One child (age 21 months) was unable to be distracted and did not complete the iontophoresis procedure. Sixteen children (42%) reported tingling and/or itching, primarily older children who were able to self-report. As shown in Table 2, redness and/or blanching at the site of the electrodes were observed in 33 children (87%). One child experienced minor blistering. All adverse effects, including the small blister, had disappeared prior to discharge from the emergency department. The mean number of minutes from the time that the iontophoresis procedure was completed until ED discharge was 188 minutes ± 122, with a range from 27 to 631 minutes. The median number of minutes was 145, or about 21⁄2 hours. Mean and median pain scores were used to describe and compare pain as a measure of tolerability for the iontophoresis procedure. Scores of ≤6 on the M-PEPPS and
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Age
N (%)
Mean age, 43 mo ± 20.4; range, 12-83 mo; median, 41 mo
Gender Boys Girls Admission diagnosis Fever, dehydration Fractures Abdominal pain Pyelonephritis Fainting Knee cellulitis Headache Hyperglycemia Dyspnea Neutropenia Postoperative tonsillectomy Epiglottitis Hemiparesis Diabetic ketoacidosis Location of PIV Hand Antecubital Wrist Missing Size of cannula 22 Gauge 24 Gauge Missing
19 (50) 19 (50) 20 (52.6) 4 (10.5) 2 (5.3) 2 (5.3) 1 (2.6) 1 (2.6) 1 (2.6) 1 (2.6) 1 (2.6) 1 (2.6) 1 (2.6) 1 (2.6) 1 (2.6) 1 (2.6) 30 (79) 4 (11) 1 (3) 3 (8) 11 (29) 26 (68) 1 (3)
PIV, Peripheral intravenous cannulation.
scores of ≤30 on the VAS were considered “mild pain.” Pain scores were assessed at 5 minutes after the start of the procedure. During the iontophoresis procedure, 32 children (85%) had M-PEPPS scores of ≤6 as determined by primary nurses, with 31 parents (82%) marking the VAS at ≤30. The mean M-PEPPS score during the procedure was 2.2 ± 3.7, with a median score of 0. The mean VAS score during the procedure was 13.8 ± 15.6, with a median score of 9. Five children reported “a little hurt,” and 1 child reported “a lot of hurt” during the iontophoresis procedure.
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TABLE 2
Tolerability during iontophoresis Adverse effects
Tingling (self-report) Redness Blanching Itching (self-report) Blistering Pain during iontophoresis Primary nurse M-PEPPS score ≤6 Child self-report “no hurt/little hurt” Parents’ perception: VAS ≤30 mm
Total No. of children N = 38 (% of children)
16 (42) 25 (66) 26 (68) 6 (16) 1 (3) 32 (84) 13/14 (93) 31 (82)
M-PEPPS, Modified Pre-Verbal, Early verbal, Pediatric Pain Scale; VAS, Visual Analogue Scale.
The primary nurse assessed this child with a score of 5 on the M-PEPPS; the parental VAS score was 26. EFFICACY
Mean and median pain scores were used to describe and compare pain at the time of the needle stick as a measure of efficacy. Pain scores were higher at the time of the needle stick than during the iontophoresis procedure. Sixteen children (42%) had M-PEPPS scores of ≤6 or mild pain, with scores ranging from 0 to 19. The mean M-PEPPS scores at the time of the needle stick was 7.3 ± 5.8, with a median score of 7. Parents assessed their children’s pain as lower than did the nurses. Twenty-five parents (65%) perceived their child’s pain as ≤30 or mild pain at needle stick. The mean VAS score at needle stick was 28.1 ± 30.3. Six children had M-PEPPS scores of greater than 6 prior to the start of the iontophoresis procedure. Three of these children continued to have high M-PEPPS scores at the time of the needle stick. A total of 4 children selfreported “a lot of hurt” at the time of the needle stick, whereas 4 children reported “a little hurt.”
correlation, interrater reliability among the primary nurses ranged from 0.92 to 0.99. Internal consistency, as measured by Cronbach’s α, was evaluated for scores at 5 minutes after the start of the iontophoresis procedure and at the time of needle stick. Cronbach’s coefficient α during the iontophoresis procedure was .92, and at the time of needle stick it was .93. VALIDITY
Validity was evaluated by correlating children’s self-reported scores, parents’ perceptions of their children’s pain as measured by the VAS, and M-PEPPS scores as assessed by primary nurses. Pain scores were significantly correlated during the iontophoresis procedure and at the time of the needle stick (Table 3). Higher correlations were found with the children’s self-report scores and both nurses’ and parents’ scores than with pain scores as reported by nurses and parents. Discussion and implications for practice
Interrater reliability among the primary nurses was used to evaluate reliability of the M-PEPPS. With use of Pearson’s
Safety of iontophoresis with lidocaine was determined by evaluating lidocaine levels in blood samples. Although only 23 blood samples (60%) were obtained, none indicated toxic levels of lidocaine in the plasma. Conclusive safety of the procedure cannot be established with the small numbers; however, the results concur with those found for adults5 and suggest that iontophoresis is safe for use in children between the ages of 12 and 84 months. The dosage used in this study was 30 mA, whereas the manufacturers have recommended 40 mA in older children and adults. It is not known if a large dose of lidocaine would produce different findings. The incidence and duration of adverse effects and pain during the procedure were measures of tolerability. Distraction, standard care during PIV cannulation in the emergency department, and starting the iontophoresis machine at low amperage were keys to completing the iontophoresis procedure. The majority of the children experienced minor adverse effects, but all were resolved by the time the children left the emergency department. Anecdotally, the blanching as observed by the investigators actually enhanced visualization of the venipuncture site. Based on pain assessments by primary nurses and parents, the procedure was well tolerated by the children. Only 15% of the scores
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EVALUATION OF THE M-PEPPS
Primary nurses reported the M-PEPPS as easy to use and intuitively practical. RELIABILITY
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were above the “mild pain” levels. These findings support further use of iontophoresis in young children prior to peripheral venipuncture. The average administration time of 20 minutes makes this procedure a feasible alternative to EMLA prior to PIV. As the investigators became more experienced in using the iontophoresis machine, the procedure went more smoothly and took less time. Efficacy of the iontophoresis procedure was evaluated by pain assessments at the time of needle stick. For most children, pain reported or observed at the time of the needle stick was “mild.” Forty-two percent of the children had M-PEPPS scores ≤6 as assessed by nurses, whereas parents perceived 65% of the children to have pain scores ≤30 on the VAS. Four of the 13 children (30%) who could selfreport pain stated that they had “a lot of hurt” at the time of the needle stick. The findings suggest that iontophoresis did not completely negate the sensation of pain at needle stick. However, it is not clear if the higher pain scores at the time of the needle stick reflected anxiety and fear of a needle or a painful experience. Many child behaviors in response to pain are similar to behaviors in response to anxiety and fear. For example, some of the children who tolerated the iontophoresis procedure well began to cry and fuss at the sight of the needle. It is also acknowledged that application of the tourniquet inflicts fear, discomfort, and, sometimes, pain. Thus, these findings for the efficacy of iontophoresis are limited by the lack of an adequate scale for assessing anxiety and fear in young children. There is no way of accurately knowing if the children were exhibiting pain or fear at the time of the needle stick. Reliability and validity evaluation of the modified version of the PEPPS supports further use of this modified version in the emergency department. The small number of children who could self-report pain scores limits some of the findings. Nurses reported that the M-PEPPS was intuitive and easy to use, reflected by high interrater reliability correlation. High internal consistency coefficients support high item to total correlation among the 5 items in the scale. Convergence validity of the M-PEPPS was demonstrated by statistically significant correlations of parent perceptions and primary nurse assessments with children’s selfreport of pain, respectively. It is impossible to determine if the observational scores were influenced by the self-report
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TABLE 3
Correlations among pain scores During iontophoresis Primary nurse M-PEPPS Parents VAS At needle stick Primary nurse M-PEPPS Parents VAS
Parents VAS
Child self-report
.37 P = .024
.59 P = .026 .63 P = .016
.47 P = .003
.77 P = .002 .92 P = .000
M-PEPPS, Modified Pre-Verbal, Early verbal, Pediatric Pain Scale; VAS, Visual Analogue Scale.
ratings of the children. Further support of construct validity should be addressed with all studies that use the M-PEPPS. Pain scores during the iontophoresis procedure were lower than at the time of the needle stick. This was expected and provides support for the validity of the M-PEPPS in assessing pain. The iontophoresis procedure, which does cause some tingling at the site of the electrodes, could be slightly painful, whereas if the iontophoresis procedure did not provide adequate dermal anesthesia, the needle stick could be quite painful. Pain scores were mild during the iontophoresis procedure. Seventy percent of the children who could self-report, 42% of the nurses, and 65% of the parents assessed pain as mild or not present at the time of the needle stick. Conclusions
Although this is a small sample, the children are similar to those admitted to other emergency departments, and the findings can potentially be generalized to other similar populations with certain caveats. Further evaluation of a 40mA dose of lidocaine is warranted. The anticipated adverse effects resolved quickly and did not create any untoward responses. Blanching actually facilitated identification of the cannulation site. The M-PEPPS, while easy to use, needs further evaluation for its validity in measuring the immediate pain response in young children.
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This study has sparked further nursing research in the emergency department. This team of staff nurse investigators and the supporting physician team have just received funding from the Emergency Medicine Foundation and the ENA Foundation for a collaborative project comparing the effectiveness of iontophoresis with lidocaine and lidocaine infusion prior to lumbar puncture in adults. Acknowledgment We thank all the nurses and physicians in the emergency department at Maine Medical Center for their support during this study.
REFERENCES
14. Young SS, Schwartz R, Sheridan MJ. EMLA cream as a topical anesthesia before office phlebotomy in children. South Med J 1996;89:1184-7. 15. Zelter L, Regalado M, Nichter LS, Barton D, Jennings S, Pitt L. Iontophoresis versus subcutaneous injection: a comparison of two methods of local anesthesia delivery in children. Pain 1991; 44:73-8. 16. Schultz AA, Murphy E, Morton J, Stempel A, Messenger-Rioux C, Bennett K. Psychometric evaluation of a pre-verbal, early verbal pediatric pain scale (PEPPS). J Pediatr Nurs 1999;4:19-27. 17. US Department of Health and Human Services, Public Health Service, Agency for Health Care Policy and Research. Acute pain management: operative or medical procedures and trauma (Clinical Practice Guideline, DHHS publication No. [AHCPR] 920032). Silver Spring (MD): AHCPR Clearinghouse; 1992.
1. Lander J, Hodgins M, Nazarali S, McTavish J, Ouellette J, Friesen E. Determinants of success and failure of EMLA. Pain 1996;64:89-97. 2. Michael A, Andrew M. The application of EMLA and glyceryl trinitrate ointment prior to venipuncture. Anaesth Intensive Care 1996;24:360-4. 3. Zempsky WT, Ashburn MA. Iontophoresis: noninvasive drug delivery. Am J Anesthesiol 1998;25:158-62. 4. IOMED Inc. NUMBY STUFF. 1999. Available from: URL: www.iomed.com 5. Ashburn MA, Gauthier M, Love G, Basta S, Gaylord B, Kester K. Iontophoretic administration of 2% lidocaine HCL and 1:100,000 epinephrine in humans. Clin J Pain 1997;13:22-6. 6. Kim MK, Kini NM, Troshynski TJ, Hennes HM. A randomized clinical trial of dermal anesthesia by iontophoresis for peripheral intravenous catheter placement in children. Ann Emerg Med 1999;33:395-9. 7. Zempsky WT, Anand KJS, Sullivan KM, Fraser D, Cucina K. Lidocaine iontophoresis for topical anesthesia before intravenous line placement in children. J Pediatr 1998;132:1061-3. 8. Greenbaum SS, Bernstein EF. Comparison of iontophoresis of lidocaine with a eutectic mixture of lidocaine and prilocaine (EMLA®) for topically administered local anesthesia. J Dermatol Surg Oncol 1994;20:379-83. 9. Manunuksela E, Korpela R. Double blind evaluation of lignocaine-prilocaine cream (EMLA) in children: effects on pain associated with venous cannulation. Br J Anaesthesiol 1986;58:12425. 10. Nott MR, Peacock JL. Relief of injection pain in adults: EMLA cream for 5 minutes before venipuncture. Anaesthesia 1990;45: 772-4. 11. Robieux I, Kumar R, Radhakrishman S, Koren G. Assessing pain and analgesia with a lidocaine-prilocaine emulsion in infants and toddlers during venipuncture. J Pediatr 1991;118:971-3. 12. Sims C. Thickly and thinly applied lignocaine-prilocaine cream prior to venipuncture in children. Anaesth Intensive Care 1991; 19:343-5. 13. Yamamoto LG, Boychuk RB. A blinded, randomized, paired, placebo-controlled trial of 20-minute EMLA cream to reduce the pain of peripheral IV cannulation in the emergency department. Am J Emerg Med 1998;16:634-6.
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Safety, Tolerability, and Efficacy of Iontophoresis With Lidocaine for Dermal Anesthesia in ED Pediatric Patients Authors: Alyce A. Schultz, RN, PhD, Tania D. Strout, RN, BSN, Pam Jordan, RN, BSN, and Barry Worthing, RN, BSN, Portland, Me
Alyce A. Schultz is Nurse Researcher; Tania D. Strout, Maine ENA, is Research Nurse Coordinator, Emergency Department; Pam Jordan, Maine ENA, is Staff Nurse, Emergency Department; and Barry Worthing, Maine ENA, is Staff Nurse, Emergency Department, Maine Medical Center, Portland, Me. Funded in part by a combined grant from Sigma Theta Tau International and the ENA Foundation. For reprints, write: Alyce A. Schultz, RN, PhD, 20 Groveside Rd, Portland, ME 04102; E-mail: [email protected]. J Emerg Nurs 2002;28:289-96. Copyright © 2002 by the Emergency Nurses Association. 0099-1767/2002 $35.00 +0 18/1/125791 doi:10.1067/men.2002.125791
Introduction: This study examined the safety, tolerability, and
efficacy of iontophoresis with 30 mA of lidocaine for dermal anesthesia in children younger than 84 months in the emergency department and the usefulness of a modified version of the Pre-Verbal, Early verbal, Pediatric Pain Scale (M-PEPPS). Methods: Three expert nurses completed the protocol for ionto-
phoresis and inserted an intravenous catheter. Parents scored pain by using the 10-cm Visual Analogue Scale, nurses used the M-PEPPS, and children, if able, self-reported pain during the procedure and at needle stick. Results: Serum lidocaine levels were within the normal laborato-
ry reference range. Adverse effects were minor and disappeared prior to discharge from the emergency department. Eighty-five percent of the children had M-PEPPS scores ≤6 during the iontophoresis procedure; 42% had scores of ≤6 at needle stick. Eighty-two percent of the parents marked the VAS as ≤30 during the procedure; 65% indicated scores of ≤30 at needle stick. Four children self-reported “a lot of pain” at needle stick. Although low to moderate, M-PEPPS scores and parental pain ratings were significantly correlated at both points in time. Discussion: Iontophoresis with lidocaine is safe for use in young
children. It does not create any long-term untoward effects and is quite well tolerated. It is not clear if the higher pain scores at needle stick reflect anxiety and fear of a needle or a painful experience.
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T
he anxiety and pain associated with venous access in the pediatric population is experienced daily by children admitted for emergency care (and their parents). Approximately 10% of the admissions to the Maine Medical Center level I emergency department are children between the ages of 1 and 7 years, and a significant number of these children require peripheral intravenous (PIV) therapy during their ED stay. In acute care settings, particularly in emergency departments, it is imperative that procedures be done in a rapid, sequential order. PIV cannulation is usually painful for the child; the pain and anxiety associated with pediatric cannulation often impede the rapidity and success of establishing PIV access. Prilocaine (EMLA) and iontophoresis of lidocaine are alternative, noninvasive treatments to intracutaneous injection of lidocaine or buffered lidocaine for obtaining topical anesthesia prior to cannulation. Prilocaine is a cream applied directly to the epidermis and covered with a semiocclusive dressing. The cream must be in place for at least 60 minutes prior to cannulation to produce adequate dermal anesthesia.1,2 In the emergency department, venous access is usually needed in less than 1 hour, and thus the use of EMLA as a topical anesthetic agent is not feasible. Background
Iontophoresis for dermal anesthesia is the introduction of water-soluble, positively charged lidocaine hydrochloride and epinephrine into the skin by a small external electric current. The transdermal iontophoresis is accomplished with use of a small, battery-operated unit with a positive and negative connection to one medicated and one dispersive electrode. The electric current, set from 0.0 to 4.0 mA, causes the medication to flow through the skin beneath the electrode, through the interstitial tissue, and back through the skin to the other electrode. The exact mechanism for the ionic transport is unclear.3 Lidocaine stabilizes the neuronal membrane, inhibiting the ionic movements required for the conduction of painful stimuli to the brain, and thus provides local anesthesia. The half-life for intravenous administration is 11⁄2 to 2 hours. Epinephrine, with its vasconstrictive property, increases the duration and depth of anesthesia and decreases the departure of lidocaine from the site. Epinephrine may
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increase the possibility of systemic absorption of lidocaine. Thirty milliamperes, the dosage used in this study, reportedly produces dermal anesthesia to an average depth of 8.4 mm, which is adequate for intravenous cannulation.4 Depending on the dosage, anesthesia is usually achieved in less than 15 minutes.5-7 Whereas numerous studies have been reported on the safety and efficacy of EMLA as a topical anesthetic agent prior to intravenous cannulation,1,2,8-14 limited studies have been published on the use of an iontophoresis system for dermal anesthesia in a pediatric population.6,7,15 No studies were found that addressed the safety of iontophoresis with lidocaine for dermal anesthesia in a pediatric population, regardless of age. Efficacy studies have only been reported for children older than 7 years,6,7 yet the iontophoresis procedure for dermal anesthesia is currently marketed for all age groups. Purpose
The primary purpose of this study was to examine the safety, tolerability, and efficacy of iontophoresis with lidocaine for dermal anesthesia prior to venous access in children between the ages of 12 and 84 months who come to the emergency department for treatment. The primary research questions was: Is iontophoresis with lidocaine effective for reducing the pain of venipuncture? The specific aims were to examine the following: (1) evidence of lidocaine in the blood following iontophoresis with 30 mA of lidocaine hydrochloride 2% with 1/100,000 epinephrine in young children; (2) adverse effects of iontophoresis with lidocaine in young children; (3) duration of the adverse effects; (4) treatment needs for resolution of adverse effects; and (5) the usefulness, reliability, and validity of a modified version of the Pre-verbal, Early Verbal Pediatric Pain Scale (M-PEPPS)16 for measuring procedural pain in young children. Methodology
The study had a prospective, descriptive design and was conducted in an emergency department that has 50,000 admissions annually, including approximately 5000 pediatric admissions. A convenience sample of children between the
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ages of 12 and 84 months was obtained. Sample size discussions with a statistician determined that 40 children would be adequate to establish the efficacy of iontophoresis in reducing the pain of venipuncture (personal communication, Dr Douglas Thompson, January 5, 2000). Inclusion criteria, in addition to age, were English-speaking parents and PIV anticipated within an hour. Children diagnosed with mental retardation, unstable vital signs, a rash, skin break, inflammation or scarring in the area of the selected venous access or electrode sites, an indwelling electrical device such as a pacemaker, a lidocaine allergy, or in need of emergent PIV were excluded. The parents of children who met the study criteria were approached by one of the primary investigators for consent after a physician had written the orders for PIV cannulation and iontophoresis. Following consent, the investigator selected the most appropriate site for cannulation. Distraction, including having parents read stories, playing with kaleidoscopes, singing, and coloring, was used prior to and during the iontophoresis procedure. The protocol for the iontophoresis procedure followed the recommendations of the manufacturer, IOMED, Inc. One milliliter of lidocaine 2% with 1:100,000 epinephrine was added to the drug electrode. This electrode was placed over the identified cannulation site and the ground electrode was placed on a major muscle of the child or the parent, at least 6 inches away from the drug electrode site (Figure 1). A Phoresor II machine, PM850, was used to give the treatment. The Phoresor II can be programmed to shut off automatically after the selected dose is attained. Safety checks, error messages, treatment time calculation, and shut-off are performed automatically. There is also a built-in option for manual shut-off if needed.4 The treatment was started at 1.0 mA and slowly increased when children did not report any tactile or tingling sensations at the cannulation site. All subjects who completed the study received a 30-mA dose of 2% lidocaine with 1:100,000 epinephrine. The average time for the procedure was 20 minutes, with a range from 10 to 45 minutes. The average time from the completion of the iontophoresis procedure to cannulation was 4.4 minutes, with a range from less than a minute to 14 minutes. The investigators stayed with the child throughout the procedure. Any adverse effect that was noticed or reported during the procedure was recorded.
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FIGURE 1
Iontophoresis Procedure: Ground electrode on large muscle with medication electrode on the hand.
Pain was assessed immediately prior to the start of the iontophoresis procedure, at 5 minutes after the start of the iontophoresis, at the conclusion of iontophoresis, and at the time of the needle stick for cannulation by the child’s primary nurse who was not a member of the research team. The primary nurse assessed pain by using the M-PEPPS and also asked the child, if he or she was able, to self-report pain using a 3-point ordinal scale, the standard pain assessment scale at the time of the study. Parents were asked to record their perceptions of their child’s pain on a 10-cm Visual Analogue Scale (VAS), the standard pain scale used with adults. All ED staff were oriented to the study. Staff nurses were educated on use of the M-PEPPS, the ordinal selfreport scale for children able to verbalize pain, and the VAS. The educational program included didactic materials and videotaped vignettes produced during the initial evaluation of the PEPPS. Interrater reliability of ≥.85 for the PEPPS among staff was established. Outcomes measures
SAFETY
Lidocaine levels in the plasma evaluated safety of the procedure. Blood samples were obtained immediately following
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Parameter
Facial
0
1
Relaxed facial expression
Cry (audible/ No cry visual) Consolability/ Pleasant, well state of integrated restfulness
Whimpering, groaning Distractible, easy to console, intermittent fussiness
2
Grimace, brows drawn together; eyes partially closed, squinting Intermittent crying
3
Sustained crying
Able to console, distract with difficulty, intermittent restlessness, irritability Body Posture Body at rest, Clenched fists, Localization with Intermittent or susrelaxed positioning curled toes and/or extension or flexion tained movement reaching for, touch- or stiff and nonmoving with or without ing wound or area rigidity Sociability Responds to voice With effort, responds and/or touch, makes to voice and/or touch, eye contact and/or makes eye contact but smiles, easy to obtain difficult to obtain or or maintain; sleeping maintain
4
Severe grimace; brows lowered, tightly drawn together; eyes tightly closed Screaming Unable to console, restlessness, sustained movement Sustained arching, flailing, thrashing and/or kicking Absent eye contact, no response to voice and/or touch
FIGURE 2
Modified Preverbal, Early Verbal Pediatric Pain Scale (M-PEPPS). (The authors are very interested in feedback on the use of this scale; please contact the authors for future use.)
PIV cannulation. Lidocaine assays, using fluorescencepolarization immunoassay, with an assay sensitivity of >0.1 µg/mL, were completed within 1 hour after arriving in the laboratory. Lidocaine values of less than 1.5 µg/mL are considered within normal limits in our laboratory. TOLERABILITY
Tolerability was evaluated by assessing and recording adverse effects and pain during the iontophoresis procedure. All skin changes, including tingling along the path of the electric current and redness, blanching, hives, itching, and/or blistering at the site of an electrode, were noted during or after the procedure and at the time of discharge from the emergency department. The primary nurses and the parents and child, if able, assessed pain prior to and during the procedure. Primary nurses assessed pain using a modified version of the PEPPS.16 The modified version (M-PEPPS) eliminates the categories of heart rate and sucking/feeding (Figure 2). Scoring in the modified scale can range from 0 to 20. Scores ≤6 are considered indicative of mild to no pain. Reevaluation of the original psychometric data for the M-PEPPS shows interrater reliability among the 4 original assessors
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for these 5 categories ranging from 0.87 to 0.94 compared with a range of 0.90 to 0.96, and intra-rater reliability ranging from 0.94 to 0.96 compared with 0.96 to 0.98 in the original evaluation. Internal consistency for the modified scale, as measured by Cronbach’s α, increased from .89 to .94. In the original testing, the 2 eliminated categories, sucking/feeding and heart rate, had low item to total scale correlation. Early construct validity was supported in the original testing by comparing changes in pre- and postmedication scores; pain scores prior to treatment averaged 12.0, ± 4.35, decreasing to 2.39 ± 3.8 following treatment (P < .001) (unpublished data, Schultz, 1999). One or both parents were asked to simultaneously and independently assess the child’s pain, using a 10-cm VAS. The VAS is the most common pain scale used in emergency departments and has been shown to correlate highly with the 0 to 10 pain scale.17 Children, if able, were asked by their primary nurses to describe their pain on an ordinal scale as “no hurt,” “a little hurt,” or “a lot of hurt.” EFFICACY
Efficacy of iontophoresis with lidocaine as a dermal anesthetic was assessed by pain measurements at the time of the
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needle stick. Primary nurses used the M-PEPPS, parents used the VAS, and children, if able, described their pain on an ordinal scale.
TABLE 1
Demographics Variable
Results
Informed consent was obtained from 40 parents. No children were able to give written assent, but all were present during the explanation of the study. Only one parent refused to participate in the study. Thirty-eight patients, 19 boys and 19 girls, completed the study. Their ages ranged from 12 to 83 months, with a mean of 43 months, ± 20.4, and a median of 41 months. Of the two who did not complete the study, one child could not be distracted enough to begin the iontophoresis procedure and one was unable to be distracted long enough to complete the iontophoresis. More than half of the children were admitted to the emergency department for fever, dehydration, or vomiting. Thirty of 38 PIVs were placed in the dorsum of the hand (Table 1). SAFETY
Serum lidocaine levels were within normal laboratory reference range of less than 1.5 µg/mL for the 23 samples that could be drawn within 30 minutes following cannulation. Lidocaine levels ranged from <0.2 to 1.0 µg/mL for 22 of the samples. One sample had no evidence of any lidocaine. TOLERABILITY
One child (age 21 months) was unable to be distracted and did not complete the iontophoresis procedure. Sixteen children (42%) reported tingling and/or itching, primarily older children who were able to self-report. As shown in Table 2, redness and/or blanching at the site of the electrodes were observed in 33 children (87%). One child experienced minor blistering. All adverse effects, including the small blister, had disappeared prior to discharge from the emergency department. The mean number of minutes from the time that the iontophoresis procedure was completed until ED discharge was 188 minutes ± 122, with a range from 27 to 631 minutes. The median number of minutes was 145, or about 21⁄2 hours. Mean and median pain scores were used to describe and compare pain as a measure of tolerability for the iontophoresis procedure. Scores of ≤6 on the M-PEPPS and
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Age
N (%)
Mean age, 43 mo ± 20.4; range, 12-83 mo; median, 41 mo
Gender Boys Girls Admission diagnosis Fever, dehydration Fractures Abdominal pain Pyelonephritis Fainting Knee cellulitis Headache Hyperglycemia Dyspnea Neutropenia Postoperative tonsillectomy Epiglottitis Hemiparesis Diabetic ketoacidosis Location of PIV Hand Antecubital Wrist Missing Size of cannula 22 Gauge 24 Gauge Missing
19 (50) 19 (50) 20 (52.6) 4 (10.5) 2 (5.3) 2 (5.3) 1 (2.6) 1 (2.6) 1 (2.6) 1 (2.6) 1 (2.6) 1 (2.6) 1 (2.6) 1 (2.6) 1 (2.6) 1 (2.6) 30 (79) 4 (11) 1 (3) 3 (8) 11 (29) 26 (68) 1 (3)
PIV, Peripheral intravenous cannulation.
scores of ≤30 on the VAS were considered “mild pain.” Pain scores were assessed at 5 minutes after the start of the procedure. During the iontophoresis procedure, 32 children (85%) had M-PEPPS scores of ≤6 as determined by primary nurses, with 31 parents (82%) marking the VAS at ≤30. The mean M-PEPPS score during the procedure was 2.2 ± 3.7, with a median score of 0. The mean VAS score during the procedure was 13.8 ± 15.6, with a median score of 9. Five children reported “a little hurt,” and 1 child reported “a lot of hurt” during the iontophoresis procedure.
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TABLE 2
Tolerability during iontophoresis Adverse effects
Tingling (self-report) Redness Blanching Itching (self-report) Blistering Pain during iontophoresis Primary nurse M-PEPPS score ≤6 Child self-report “no hurt/little hurt” Parents’ perception: VAS ≤30 mm
Total No. of children N = 38 (% of children)
16 (42) 25 (66) 26 (68) 6 (16) 1 (3) 32 (84) 13/14 (93) 31 (82)
M-PEPPS, Modified Pre-Verbal, Early verbal, Pediatric Pain Scale; VAS, Visual Analogue Scale.
The primary nurse assessed this child with a score of 5 on the M-PEPPS; the parental VAS score was 26. EFFICACY
Mean and median pain scores were used to describe and compare pain at the time of the needle stick as a measure of efficacy. Pain scores were higher at the time of the needle stick than during the iontophoresis procedure. Sixteen children (42%) had M-PEPPS scores of ≤6 or mild pain, with scores ranging from 0 to 19. The mean M-PEPPS scores at the time of the needle stick was 7.3 ± 5.8, with a median score of 7. Parents assessed their children’s pain as lower than did the nurses. Twenty-five parents (65%) perceived their child’s pain as ≤30 or mild pain at needle stick. The mean VAS score at needle stick was 28.1 ± 30.3. Six children had M-PEPPS scores of greater than 6 prior to the start of the iontophoresis procedure. Three of these children continued to have high M-PEPPS scores at the time of the needle stick. A total of 4 children selfreported “a lot of hurt” at the time of the needle stick, whereas 4 children reported “a little hurt.”
correlation, interrater reliability among the primary nurses ranged from 0.92 to 0.99. Internal consistency, as measured by Cronbach’s α, was evaluated for scores at 5 minutes after the start of the iontophoresis procedure and at the time of needle stick. Cronbach’s coefficient α during the iontophoresis procedure was .92, and at the time of needle stick it was .93. VALIDITY
Validity was evaluated by correlating children’s self-reported scores, parents’ perceptions of their children’s pain as measured by the VAS, and M-PEPPS scores as assessed by primary nurses. Pain scores were significantly correlated during the iontophoresis procedure and at the time of the needle stick (Table 3). Higher correlations were found with the children’s self-report scores and both nurses’ and parents’ scores than with pain scores as reported by nurses and parents. Discussion and implications for practice
Interrater reliability among the primary nurses was used to evaluate reliability of the M-PEPPS. With use of Pearson’s
Safety of iontophoresis with lidocaine was determined by evaluating lidocaine levels in blood samples. Although only 23 blood samples (60%) were obtained, none indicated toxic levels of lidocaine in the plasma. Conclusive safety of the procedure cannot be established with the small numbers; however, the results concur with those found for adults5 and suggest that iontophoresis is safe for use in children between the ages of 12 and 84 months. The dosage used in this study was 30 mA, whereas the manufacturers have recommended 40 mA in older children and adults. It is not known if a large dose of lidocaine would produce different findings. The incidence and duration of adverse effects and pain during the procedure were measures of tolerability. Distraction, standard care during PIV cannulation in the emergency department, and starting the iontophoresis machine at low amperage were keys to completing the iontophoresis procedure. The majority of the children experienced minor adverse effects, but all were resolved by the time the children left the emergency department. Anecdotally, the blanching as observed by the investigators actually enhanced visualization of the venipuncture site. Based on pain assessments by primary nurses and parents, the procedure was well tolerated by the children. Only 15% of the scores
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EVALUATION OF THE M-PEPPS
Primary nurses reported the M-PEPPS as easy to use and intuitively practical. RELIABILITY
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were above the “mild pain” levels. These findings support further use of iontophoresis in young children prior to peripheral venipuncture. The average administration time of 20 minutes makes this procedure a feasible alternative to EMLA prior to PIV. As the investigators became more experienced in using the iontophoresis machine, the procedure went more smoothly and took less time. Efficacy of the iontophoresis procedure was evaluated by pain assessments at the time of needle stick. For most children, pain reported or observed at the time of the needle stick was “mild.” Forty-two percent of the children had M-PEPPS scores ≤6 as assessed by nurses, whereas parents perceived 65% of the children to have pain scores ≤30 on the VAS. Four of the 13 children (30%) who could selfreport pain stated that they had “a lot of hurt” at the time of the needle stick. The findings suggest that iontophoresis did not completely negate the sensation of pain at needle stick. However, it is not clear if the higher pain scores at the time of the needle stick reflected anxiety and fear of a needle or a painful experience. Many child behaviors in response to pain are similar to behaviors in response to anxiety and fear. For example, some of the children who tolerated the iontophoresis procedure well began to cry and fuss at the sight of the needle. It is also acknowledged that application of the tourniquet inflicts fear, discomfort, and, sometimes, pain. Thus, these findings for the efficacy of iontophoresis are limited by the lack of an adequate scale for assessing anxiety and fear in young children. There is no way of accurately knowing if the children were exhibiting pain or fear at the time of the needle stick. Reliability and validity evaluation of the modified version of the PEPPS supports further use of this modified version in the emergency department. The small number of children who could self-report pain scores limits some of the findings. Nurses reported that the M-PEPPS was intuitive and easy to use, reflected by high interrater reliability correlation. High internal consistency coefficients support high item to total correlation among the 5 items in the scale. Convergence validity of the M-PEPPS was demonstrated by statistically significant correlations of parent perceptions and primary nurse assessments with children’s selfreport of pain, respectively. It is impossible to determine if the observational scores were influenced by the self-report
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TABLE 3
Correlations among pain scores During iontophoresis Primary nurse M-PEPPS Parents VAS At needle stick Primary nurse M-PEPPS Parents VAS
Parents VAS
Child self-report
.37 P = .024
.59 P = .026 .63 P = .016
.47 P = .003
.77 P = .002 .92 P = .000
M-PEPPS, Modified Pre-Verbal, Early verbal, Pediatric Pain Scale; VAS, Visual Analogue Scale.
ratings of the children. Further support of construct validity should be addressed with all studies that use the M-PEPPS. Pain scores during the iontophoresis procedure were lower than at the time of the needle stick. This was expected and provides support for the validity of the M-PEPPS in assessing pain. The iontophoresis procedure, which does cause some tingling at the site of the electrodes, could be slightly painful, whereas if the iontophoresis procedure did not provide adequate dermal anesthesia, the needle stick could be quite painful. Pain scores were mild during the iontophoresis procedure. Seventy percent of the children who could self-report, 42% of the nurses, and 65% of the parents assessed pain as mild or not present at the time of the needle stick. Conclusions
Although this is a small sample, the children are similar to those admitted to other emergency departments, and the findings can potentially be generalized to other similar populations with certain caveats. Further evaluation of a 40mA dose of lidocaine is warranted. The anticipated adverse effects resolved quickly and did not create any untoward responses. Blanching actually facilitated identification of the cannulation site. The M-PEPPS, while easy to use, needs further evaluation for its validity in measuring the immediate pain response in young children.
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This study has sparked further nursing research in the emergency department. This team of staff nurse investigators and the supporting physician team have just received funding from the Emergency Medicine Foundation and the ENA Foundation for a collaborative project comparing the effectiveness of iontophoresis with lidocaine and lidocaine infusion prior to lumbar puncture in adults. Acknowledgment We thank all the nurses and physicians in the emergency department at Maine Medical Center for their support during this study.
REFERENCES
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