Alleviation of the pain of heel prick in preterm infants

Improving the treatment of infant pain

Purpose of review

Pain management presents a major challenge in neonatal care. Newborn infants who require medical treatment can undergo frequent invasive procedures during a critical period of neurodevelopment. However, adequate analgesic provision is infrequently and inconsistently provided for acute noxious procedures because of limited and conflicting evidence regarding analgesic efficacy and safety of most commonly used pharmacological agents. Here, we review recent advances in the measurement of infant pain and discuss clinical trials that assess the efficacy of pharmacological analgesia in infants.

Recent findings

Recently developed measures of noxious-evoked brain activity are sensitive to analgesic modulation, providing an objective quantitative outcome measure that can be used in clinical trials of analgesics.

Summary

Noxious stimulation evokes changes in activity across all levels of the infant nervous system, including reflex activity, altered brain activity and behaviour, and long-lasting changes in infant physiological stability. A multimodal approach is needed if we are to identify efficacious and well tolerated analgesic treatments. Well designed clinical trials are urgently required to improve analgesic provision in the infant population.

Nociceptive brain activity as a measure of analgesic efficacy in infants

Pain in infants is undertreated and poorly understood, representing a major clinical problem. In part, this is due to our inability to objectively measure pain in nonverbal populations. We present and validate an electroencephalography-based measure of infant nociceptive brain activity that is evoked by acute noxious stimulation and is sensitive to analgesic modulation. This measure should be valuable both for mechanistic investigations and for testing analgesic efficacy in the infant population.

Topical anaesthesia for needle-related pain in newborn infants

BACKGROUND

Hospitalised newborn neonates frequently undergo painful invasive procedures that involve penetration of the skin and other tissues by a needle. One intervention that can be used prior to a needle insertion procedure is application of a topical local anaesthetic.

OBJECTIVES

To evaluate the efficacy and safety of topical anaesthetics such as amethocaine and EMLA in newborn term or preterm infants requiring an invasive procedure involving puncture of skin and other tissues with a needle.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, Embase and CINAHL up to 15 May 2016; previous reviews including cross-references, abstracts, and conference proceedings. We contacted expert informants. We contacted authors directly to obtain additional data. We imposed no language restrictions.

SELECTION CRITERIA

Randomised, quasi-randomised controlled trials, and cluster and cross-over randomised trials that compared the topical anaesthetics amethocaine and eutectic mixture of local anaesthetics (EMLA) in terms of anaesthetic efficacy and safety in newborn term or preterm infants requiring an invasive procedure involving puncture of skin and other tissues with a needle DATA COLLECTION AND ANALYSIS: From the reports of the clinical trials we extracted data regarding clinical outcomes including pain, number of infants with methaemoglobin level 5% and above, number of needle prick attempts prior to successful needle-related procedure, crying, time taken to complete the procedure, episodes of apnoea, episodes of bradycardia, episodes of oxygen desaturation, neurodevelopmental disability and other adverse events.

MAIN RESULTS

Eight small randomised controlled trials met the inclusion criteria (n = 506). These studies compared either EMLA and placebo or amethocaine and placebo. No studies compared EMLA and amethocaine. We were unable to meta-analyse the outcome of pain due to differing outcome measures and methods of reporting. For EMLA, two individual studies reported a statistically significant reduction in pain compared to placebo during lumbar puncture and venepuncture. Three studies found no statistical difference between the groups during heel lancing. For amethocaine, three studies reported a statistically significant reduction in pain compared to placebo during venepuncture and one study reported a statistically significant reduction in pain compared to placebo during cannulation. One study reported no statistical difference between the two groups during intramuscular injection.One study reported no statistical difference between EMLA and the placebo group for successful venepuncture at first attempt. One study similarly reported no statistically significant difference between Amethocaine and the placebo group for successful cannulation at first attempt.Risk for local redness, swelling or blanching was significantly higher with EMLA (typical risk ratio (RR) 1.65, 95% confidence interval (CI) 1.24 to 2.19; typical risk difference (RD) 0.17, 95% CI 0.09 to 0.26; n = 272; number needed to treat for an additional harmful outcome (NNTH) 6, 95% CI 4 to 11; I² = 92% indicating considerable heterogeneity) although not for amethocaine (typical RR 2.11, 95% CI 0.72 to 6.16; typical RD 0.05, 95% CI -0.02 to 0.11, n = 221). These local skin reactions for EMLA and amethocaine were reported as short-lasting. Two studies reported no methaemoglobinaemia with single application of EMLA. The quality of the evidence on outcomes assessed according to GRADE was low to moderate.

AUTHORS' CONCLUSIONS

Overall, all the trials were small, and the effects of uncertain clinical significance. The evidence regarding the effectiveness or safety of the interventions studied is inadequate to support clinical recommendations. There has been no evaluation regarding any long-term effects of topical anaesthetics in newborn infants.High quality studies evaluating the efficacy and safety of topical anaesthetics such as amethocaine and EMLA for needle-related pain in newborn term or preterm infants are required. These studies should aim to determine efficacy of these topical anaesthetics and on homogenous groups of infants for gestational age. While there was no methaemoglobinaemia in the studies that reported methaemoglobin, the efficacy and safety of EMLA, especially in very preterm infants, and for repeated application, need to be further evaluated in future studies.

Randomized controlled trial of topical EMLA and breastfeeding for reducing pain during wDPT vaccination

The primary objective was to evaluate the analgesic effect of a eutectic mixture of local anesthetics (EMLA) during whole cell DPT vaccination. The secondary objective was to evaluate if the analgesic effect of EMLA was synergistic to breastfeeding. A randomized, placebo-controlled trial was done to include infants of up to 3 months of age who came for their first DPT vaccination. The outcome variables were duration of cry, latency of onset of cry, and Modified Facial Coding Score. Thirty babies were enrolled in each of three groups. The groups did not differ significantly in baseline characteristics. Median (interquartile range) of duration of cry was least [34.6 (24.1-72.2) s] in babies receiving EMLA cream with breastfeeding (EB group), followed by 94.2 (46.1-180) s in babies receiving EMLA cream with oral distilled water (EW group), as compared to 180.0 (180-180) s in babies receiving placebo cream with oral distilled water (PCW group) (p < 0.05). Mean (SD) of latency of cry was significantly greater in EB group [2.4 (1.14) s] and EW group [1.9 (0.62) s] as compared to babies in PCW group [1.5 (0.47) s] (p < 0.05), but the difference between EB and EW groups was not significant. Modified Facial Coding Score was significantly lower in EB group as compared to the other groups (p < 0.05).

CONCLUSIONS

Topical EMLA is effective in reducing pain and has a synergistic effect in analgesia when combined with breastfeeding during vaccination in infants.

Venepuncture versus heel lance for blood sampling in term neonates

BACKGROUND

Heel lance has been the conventional method of blood sampling in neonates for screening tests. Neonates undergoing heel lance experience pain which cannot be completely alleviated.

OBJECTIVES

To determine whether venepuncture or heel lance is less painful and more effective for blood sampling in term neonates.

SEARCH STRATEGY

Randomized or quasi-randomised controlled trials comparing pain response to venepuncture versus heel lance were identified by searching the Cochrane Central Regsiter of Controlled Trials (CENTRAL, The Cochrane Library), MEDLINE, EMBASE, CINAHL, and clinical trials registries in May 2011.

SELECTION CRITERIA

Trials comparing pain response to venepuncture versus heel lance with or with out the use of a sweet tasting solution as a co-intervention in term neonates.

DATA COLLECTION AND ANALYSIS

Outcomes included pain response to venepuncture versus heel lance with or without the use of a sweet tasting solution using validated pain measures, the need of repeat sampling and cry characteristics. Analyses included typical relative risk (RR), risk difference (RD), number needed to treat (NNT), weighted mean difference (WMD) and standardized mean difference (SMD) with their 95% confidence intervals (CI). Between study heterogeneity was reported including the I squared (I(2)) test.

MAIN RESULTS

Six studies (n = 478) of variable quality were included. A composite outcome of Infant Pain Scale (NIPS), Neonatal Facial Action Coding System (NFCS) and/or Premature Infant Pain Profile (PIPP) score was reported in 288 infants, who did not receive a sweet tasting solution. Meta-analysis showed a significant reduction in the venepuncture versus the heel lance group (SMD -0.76, 95% CI -1.00 to -0.52; I(2) = 0%). When a sweet tasting solution was provided the SMD remained significant favouring the venepuncture group (SMD - 0.38, 95% CI -0.69 to -0.07). The typical RD for requiring more than one skin puncture for venepuncture versus heel lance (reported in 4 studies; n = 254) was -0.34 (95% CI -0.43 to -0.25; I(2) = 97%). The NNT to avoid one repeat skin puncture was 3 (95% CI 2 to 4). Cry characteristics favoured the venepuncture group but the differences were reduced by the provision of sweet tasting solutions prior to either procedure.

AUTHORS' CONCLUSIONS

Venepuncture, when performed by a skilled phlebotomist, appears to be the method of choice for blood sampling in term neonates. The use of a sweet tasting solution further reduces the pain.Further well designed randomised controlled trials should be conducted in settings where several individuals perform the procedures.

Does topical amethocaine gel reduce pain from heel prick blood sampling in premature infants? A randomized double-blind cross-over controlled study

BACKGROUND

Heel prick blood sampling is the most common painful invasive procedure performed on neonates. Currently, there are no effective ways to provide pain relief from this painful procedure.

OBJECTIVE

To assess the efficacy of the topical anesthetic amethocaine 4% gel (Ametop, Smith & Nephew Inc, St Laurent) in reducing the pain of heel prick blood sampling in neonates.

METHODS

A randomized, double-blind, placebo controlled, crossover trial was conducted. Neonates between 33 to 37 weeks' gestational age in their first seven days of life were eligible. Heel prick blood sampling was performed on each participant twice. Each infant was randomly assigned to receive either amethocaine 4% gel or placebo to the heel for the first prick, and then received the alternative agent for the second prick. Prick pain was assessed using both Premature Infant Pain Profile (PIPP) and Neonatal Infant Pain Scale (NIPS). Squeeze pain was assessed by NIPS.

RESULTS

Ten babies were recruited. There were no significant differences in the average PIPP and NIPS scores between the treatment and placebo groups for both prick and squeeze pains from heel prick blood sampling. For prick pain, linear-regression showed significant correlation between the PIPP and NIPS scores. No adverse reactions were observed after application of either the active or placebo agents.

CONCLUSION

Topical amethocaine 4% gel is not shown to reduce prick and squeeze pains significantly from heel prick blood sampling in neonates between 33 to 37 weeks' gestational age. Further studies are needed to find ways to provide effective pain relief from this common procedure.

Iatrogenic skin injury in the neonatal intensive care unit

Although neonatal care has become more and more meticulous with significant changes in technology in the neonatal intensive care unit (NICU) in the past 50 years, iatrogenic cutaneous injuries continue to occur. Although the incidence of severe injuries is decreasing because the more difficult procedures are being replaced by improved techniques, skin injuries have not yet been completely eliminated. However, the nature and causes of cutaneous injuries have changed, and the injuries are frequent but generally minor. The major risk factors are low birth weight, gestational age, length of stay, a central venous line, mechanical ventilation, and support with continuous positive airway pressure. The rate of iatrogenic events is about 57% at gestational ages of 24-27 weeks, compared with 3% at term. There are no current comprehensive reviews of iatrogenic cutaneous injury. The purpose of this review is to describe the iatrogenic cutaneous injuries that may occur in the newborns as a consequence of perinatal and postnatal medical procedures. With increased survival of extremely-low-birth-weight (ELBW) infants and changing modes of management in the NICU, neonatologists must make every effort to recognize injuries and prevent their occurrence in the NICU.

Evaluation of hemoglobin interference in capillary heel-stick samples collected for determination of neonatal bilirubin

OBJECTIVE

In this study, we determined the assay performance criteria necessary to produce acceptable results for >or=98% of neonate bilirubin samples collected by capillary heel-stick.

STUDY DESIGN AND METHODS

We determined serum free hemoglobin levels in 151 heel-stick serum samples to determine the hemolysis level. We then tested the effect of hemolysis on total bilirubin levels determined by four commercially available assays.

RESULTS

The mean level of serum free hemoglobin was 1.62 g/L. Of the serum total bilirubin assays tested, the Total Bilirubin Special (Roche Diagnostics) and the TBILI (Roche Diagnostics) reagents did not show significant interference at the concentrations of free hemoglobin observed in >or=98% of heel-stick samples. The Vitros Bu/Bc slide (Ortho-Clinical Diagnostics) showed significant interference only at normal bilirubin concentrations; while the Bilirubin DPD reagent (Amresco Inc.) showed significant interference starting at hemoglobin concentrations of 1.0 g/L.

CONCLUSIONS

Bilirubin assays that are not sensitive to approximately 6 g/L free hemoglobin should provide accurate results for most samples obtained via capillary heel-stick. Of the four assays tested, the Bilirubin DPD reagent (Amresco Inc.) was the most susceptible to the presence of free hemoglobin and will result in a higher rejection rate of neonate capillary heel-stick samples.

Venepuncture versus heel lance for blood sampling in term neonates

BACKGROUND

Heel lance has been the conventional method of blood sampling in neonates for screening tests. Neonates undergoing this procedure experience pain. Despite various studies evaluating the role of pharmacological and non-pharmacological interventions to date, there are no effective and practical methods to alleviate pain from heel lance.

OBJECTIVES

To determine whether venepuncture or heel lance is less painful and more effective for blood sampling in term neonates.

SEARCH STRATEGY

Systematic search was performed in accordance with the Cochrane Neonatal Collaborative Review Group. Randomized controlled trials which compared pain response to venepuncture vs. heel lance were identified using MEDLINE (1966 - June 2007), EMBASE (1980 - June 2007), CINAHL (1982 - June 2007), Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2007), reference lists of identified trials and personal files. No language restrictions were applied.

SELECTION CRITERIA

Randomized controlled trials which compared pain response to venepuncture vs. heel lance were selected for this review.

DATA COLLECTION AND ANALYSIS

Data regarding the primary outcome of pain response to venepuncture vs. heel lance as assessed by validated pain measures were abstracted. Secondary outcomes included the need of repeat blood sampling, bruising/hematoma at local site, and parental perception of their own anxiety and infant's pain. All data were analysed using RevMan 4.2.10. When possible, meta-analyses were performed using relative risk (RR) and risk difference (RD), along with their 95% confidence intervals (CI). If RD was significant, number needed to treat (NNT) was calculated. Weighted mean difference (WMD) was used for continuous data. When present, statistically significant between study heterogeneity was reported including the I squared (I(2) ) test.

MAIN RESULTS

Five trials were eligible for inclusion in the review (including one additional trial identified in this update). Pain assessments were made using validated pain measures including Neonatal Infant Pain Scale (NIPS), Neonatal Facial Action Coding System (NFCS), Premature Infant Pain Profile (PIPP) score and cry characteristics. Two trials did not report on outcomes for all enrolled infants (not intention to treat analyses). Despite the many different pain measures used, all studies showed statistically significantly lower pain scores for venepuncture as compared to heel lance. A meta-analysis of the NIPS scores during the first minute of the procedure (reported in two studies) was statistically significantly lower in the venepuncture group compared to the heel lance group [typical WMD -1.84 (95% CI -2.61, -1.06)]. There was no statistically significant heterogeneity for this outcome (p = 0.22; I(2) 33.3%). The typical RR for requiring more than one skin puncture for venepuncture vs. heel lance (reported in 4 studies) was 0.30 (95% CI 0.18, 0.49). The RD was -0.31 (95% CI -0.41, -0.22). For this outcome there was statistically significant between study heterogeneity (for RR, p = 0.02, I(2 )74.3%; for RD, p < 0.00001, I(2) 96.6%). The number needed to treat (NNT) to avoid one repeat skin puncture was 3 (95% CI 2, 5). In one study, maternal anxiety was noted to be higher in the venepuncture group as compared to heel lance group prior to the procedure; however, after observing the procedure, mothers rated their infant's pain to be lower in the venepuncture group.

AUTHORS' CONCLUSIONS

Venepuncture, when performed by a skilled phlebotomist, appears to be the method of choice for blood sampling in term neonates. For each three venepunctures instead of heel lance, the need for one additional skin puncture can be avoided.Further well designed randomized controlled trials need to be conducted. The interventions should be compared in settings where several individuals perform the venepuncture and/or the heel lance.

Analgesia in preterm newborns: the comparative effects of sucrose and glucose

The aim of this study was to evaluate the effectiveness of different oral carbohydrate solutions for alleviation of pain in healthy preterm babies. Thirty-one preterm infants who were having blood drawn by heel prick were given 2 ml of solution A (20% sucrose), solution B (20% glucose) or solution C (placebo, sterile water) into the mouth, 2 min before lancing. Behavioural responses to this painful stimulus were measured by duration of crying and facial expressions (Neonatal Facial Coding System, NFCS) and physiological responses were measured by heart rate (HR), respiratory rate (RR), and oxygen saturation changes (SaO(2)). Infants had a mean birth weight (+/-SD) of 1,401 g (406), gestational age of 30.5 weeks (2.7); at the time of the procedure the postmenstrual age was 32.3 weeks (1.5). There was no significant difference in the time spent squeezing the heel between the three groups (P = 0.669). After the heel prick of both the sucrose and glucose groups the duration of first cry and total crying time was significantly reduced (P = 0.005 and P = 0.007). When the babies received placebo they showed a significantly higher NFCS score at 4 and 5 min after the heel prick (P = 0.009 and 0.046 respectively). Following painful stimulus HR increased significantly in the first 3 min compared with baseline, and at the first minute the mean of the HR was found to be significantly higher in the placebo group than in the sucrose and glucose groups (P = 0.007). We concluded that both sucrose and glucose administered orally before a heel prick reduce the pain response in preterm infants.

Topical anesthesia in neonates: clinical practices and practical considerations

During the past two decades there has been a substantial increase in the number and types of topical anesthetics available. Options for the prevention of neonatal pain associated with skin-breaking procedures were previously limited to injections of lidocaine hydrochloride. Topical anesthetics are now available as creams, gels, and a heat-activated patch system. Although lidocaine injection continues to be widely used for pain associated with circumcision, lumbar puncture, or placement of central venous lines, practical information regarding the use of newer agents in the neonate is needed. This review seeks to expand the options for topical anesthesia in neonates.

Evaluation and development of potentially better practices to improve pain management of neonates

OBJECTIVE

Despite increased knowledge, improved options, and regulatory mandates, pain management of neonates remains inadequate, promoted by the ineffective translation of research data into clinical practice. The Neonatal Intensive Care Quality Improvement Collaborative 2002 was created to provide participating NICUs the tools necessary to translate research, related to prevention and treatment of neonatal pain, into practice. The objective for this study was to use proven quality improvement methods to develop a process to improve neonatal pain management collaboratively.

METHODS

Twelve members of the Neonatal Intensive Care Quality Improvement Collaborative 2002 formed an exploratory group to improve neonatal pain management. The exploratory group established group and site-specific goals and outcome measures for this project. Group members crafted a list of potentially better practices on the basis of the available literature, encouraged implementation of the potentially better practices at individual sites, developed a database for sharing information, and measured baseline outcomes.

RESULTS

The goal "improve the assessment and management of infants experiencing pain in the NICU" was established. In addition, each site within the group identified local goals for improvement in neonatal pain management. Data from 7 categories of neonates (N = 277) were collected within 48 hours of NICU admission to establish baseline data for clinical practices. Ten potentially better practices were developed for prioritized pain conditions, and 61 potentially better practices were newly implemented at the 12 participating sites. Various methods were used for pain assessment at the participating centers. At baseline, heel sticks were used more frequently than peripheral intravenous insertions or venipunctures, with substantial variability in the number of avoidable procedures between centers. Pain was assessed in only 17% of procedures, and analgesic interventions were performed in 19% of the procedures at baseline.

CONCLUSIONS

Collaborative use of quality improvement methods resulted in the creation of self-directed, efficient, and effective processes to improve neonatal pain management. Group establishment of potentially better practices, collective and site-specific goals, and extensive baseline data resulted in accelerated implementation of clinical practices that would not likely occur outside a collaborative setting.

Analgesia and local anesthesia during invasive procedures in the neonate

BACKGROUND

Preterm and full-term neonates admitted to the neonatal intensive care unit or elsewhere in the hospital are routinely subjected to invasive procedures that can cause acute pain. Despite published data on the complex behavioral, physiologic, and biochemical responses of these neonates and the detrimental short- and long-term clinical outcomes of exposure to repetitive pain, clinical use of pain-control measures in neonates undergoing invasive procedures remains sporadic and suboptimal. As part of the Newborn Drug Development Initiative, the US Food and Drug Administration and the National Institute of Child Health and Human Development invited a group of international experts to form the Neonatal Pain Control Group to review the therapeutic options for pain management associated with the most commonly performed invasive procedures in neonates and to identify research priorities in this area.

OBJECTIVE

The goal of this article was to review and synthesize the published clinical evidence for the management of pain caused by invasive procedures in preterm and full-term neonates.

METHODS

Clinical studies examining various therapies for procedural pain in neonates were identified by searches of MEDLINE (1980-2004), the Cochrane Controlled Trials Register (The Cochrane Library, Issue 1, 2004), the reference lists of review articles, and personal files. The search terms included specific drug names, infant-newborn, infant-preterm, and pain, using the explode function for each key word. The English-language literature was reviewed, and case reports and small case series were discarded.

RESULTS

The most commonly performed invasive procedures in neonates included heel lancing, venipuncture, IV or arterial cannulation, chest tube placement, tracheal intubation or suctioning, lumbar puncture, circumcision, and SC or IM injection. Various drug classes were examined critically, including opioid analgesics, sedative/hypnotic drugs, nonsteroidal anti-inflammatory drugs and acetaminophen, injectable and topical local anesthetics, and sucrose. Research considerations related to each drug category were identified, potential obstacles to the systematic study of these drugs were discussed, and current gaps in knowledge were enumerated to define future research needs. Discussions relating to the optimal design for and ethical constraints on the study of neonatal pain will be published separately. Well-designed clinical trials investigating currently available and new therapies for acute pain in neonates will provide the scientific framework for effective pain management in neonates undergoing invasive procedures.

State of the science: procedural pain management in the neonate

Neonates in the neonatal intensive care unit experience painful procedures. Over the last 10 years, investigators have examined several pharmacologic and nonpharmacolgic treatment strategies to decrease or eliminate the pain associated with mechanical ventilation, endotrachial intubation, insertion of percutaneous or central venous lines, heel stick, and venipuncture. These procedures and others are addressed as well as the reported severity of pain associated with these procedures. Progress has been made in the past decade to establish evidence-based treatments that will help the clinician more effectively relieve neonatal stress and pain when performing many routine procedures.

Skin-to-Skin Contact (Kangaroo Care) Analgesia for Preterm Infant Heel Stick

The purpose of the study was to compare a heel stick conducted during Kangaroo Care (skin-to-skin contact) with the mother to a heel stick in a warmer in reducing premature infant physiologic and behavioral pain responses. Twenty-four premature infants in a university-based neonatal intensive care unit were recruited and randomized to 2 sequences: sequence A group received 3 hours of Kangaroo Care (with a heel stick in Kangaroo Care) followed by 3 hours in a warmer (with a heel stick in the warmer). Sequence B group had warmer care and a heel stick (in the warmer) before Kangaroo Care and a heel stick (in Kangaroo Care). Heart rate, respiratory rate, oxygen saturation, crying time, and behavioral state were measured before, during, and after heel stick. Repeated measures ANOVA and Mann Whitney U statistics were performed. Heart rate and length of crying in response to pain were significantly reduced during Kangaroo Care and the Kangaroo Care heel stick as compared to when infants were in the warmer and had a heel stick in the warmer. Three infants did not cry at all during the Kangaroo Care heel stick; infants slept more during Kangaroo Care than in the warmer. Kangaroo Care positioning before and during heel stick is a simple and inexpensive analgesic intervention to ameliorate pain in stable premature infants.

A critical review of the topical local anesthetic amethocaine (Ametop) for pediatric pain

A topical formulation of the ester-type local anesthetic amethocaine (tetracaine) [Ametop ] is currently available for reducing pain from cutaneous procedures such as venipuncture. The Ametop mark preparation contains 40 mg of amethocaine base (4% w/w) and produces anesthesia within 30-45 minutes of application; duration of action ranges from 4 to 6 hours. Clinical studies have demonstrated the superiority of the 4% amethocaine preparation over placebo in pediatric populations for indications such as intravenous cannulation, vaccination, and venipuncture. Amethocaine has been shown to produce anesthesia comparable to that of 5% lidocaine-prilocaine for procedures such as venipuncture and accessing centrally placed devices; in general, anesthesia was achieved more rapidly with amethocaine than lidocaine-prilocaine. In the neonatal population amethocaine was found to be ineffective at reducing the pain of heel prick and peripherally inserted central catheters. Depending on the type of procedure, amethocaine application times between 30 and 60 minutes have produced clinically acceptable anesthesia; application times <30 minutes have not been associated with reliable anesthesia. The 4% amethocaine preparation is well tolerated; the most commonly reported local skin reaction is transient local erythema while local edema and itching have been reported more rarely. There have been no accounts of systemic toxicity with topical use of the preparation. Several cases of sensitization have been described in adults upon repeated exposure to topical amethocaine. In summary, the novel preparation of 4% amethocaine gel has been shown to be clinically effective for managing pain associated with minor cutaneous procedures while maintaining a good tolerability profile. Amethocaine has also demonstrated similar efficacy to lidocaine-prilocaine when appropriate application times are used; the more rapid onset of action and extended duration of action of amethocaine may make it more useful than lidocaine-prilocaine in busy clinical settings.

EMLA for painful procedures in infants

Based on the content of the article, you will be able to: Identify the two drugs in EMLA and the youngest pediatric age for its approved use. List the procedures for which EMLA has been used to control pain in infants. Describe the efficacy of EMLA vs. other agents in treating pain. Discuss the potential adverse effects of EMLA in infants. See page 48 for instructions.

Venepuncture versus heel lance for blood sampling in term neonates

BACKGROUND

Heel lance has been the conventional method of blood sampling in neonates for screening tests. Neonates undergoing this procedure experience pain. Despite various studies evaluating the role of pharmacological and non-pharmacological interventions to date, there are no effective and practical methods to alleviate pain from heel lance.

OBJECTIVES

To determine whether venepuncture or heel lance is less painful and more effective for blood sampling in term neonates.

SEARCH STRATEGY

Systematic search in accordance with the Cochrane Neonatal Collaborative Review Group. All randomized controlled trials which compared pain response to venepuncture vs. heel lance were identified using MEDLINE (1966-June 2004), EMBASE (1980-June 2004), CINAHL (1982-June 2004, Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2004), reference lists of identified trials and personal files. No language restrictions were applied.

SELECTION CRITERIA

Randomized controlled trials which compared pain response to venepuncture vs. heel lance were selected for this review.

DATA COLLECTION AND ANALYSIS

Data regarding the primary outcome of pain response to venepuncture vs. heel lance as assessed by validated pain measures were abstracted. Secondary outcomes including the need of repeat blood sampling, bruising/hematoma at local site, and parental perception of their own anxiety and infant's pain were abstracted. All data were analysed using RevMan 4.2. When possible, meta-analysis was done using relative risk (RR) and risk difference (RD), along with their 95% confidence intervals (CI). If RD was significant, number needed to treat (NNT) was calculated. Weighted mean difference (WMD) was used for continuous data. When present, statistically significant between study heterogeneity was reported including the I(2) test.

MAIN RESULTS

Four trials were eligible for inclusion in the review. Pain assessments were made using validated pain measures including Neonatal Infant Pain Scale (NIPS), Neonatal Facial Action Coding System (NFCS), Premature Infant Pain Profile (PIPP) score and cry characteristics. Two trials did not report on outcomes for all enrolled infants (not intention to treat analyses). Despite the heterogeneity in the pain measures used, all studies showed statistically significantly lower pain scores for venepuncture as compared to heel lance. A meta-analysis of the NIPS scores during the first minute of the procedure (reported in two studies) was statistically significantly decreased in the VP group compared to the HL group [WMD -1.84 (95% CI -2.61, -1.06)]. There was no statistically significant heterogeneity for this outcome (p = 0.22; I(2) 33.3%). The RR for requiring more than one skin puncture for venepuncture vs. heel lance (reported in 3 studies) was 0.30 (95% CI 0.18, 0.49. The risk difference was -39% (95% CI -50%, -28%). For this outcome there was statistically significant between study heterogeneity (for RR, p=0.02, I(2 )74.3%; for RD, p=0.0001, I(2) 88.9%). The number needed to treat (NNT) to avoid one repeat skin puncture was 3 (95% CI 2, 4). In one study, maternal anxiety was noted to be higher in the venepuncture group as compared to heel lance group prior to the procedure; however, after observing the procedure, mothers rated their infant's pain to be lower in the venepuncture group.

REVIEWERS' CONCLUSIONS

Venepuncture, when performed by a skilled phlebotomist, appears to be the method of choice for blood sampling in term neonates. For each three venepunctures instead of heel lance, the need for one additional skin puncture can be avoided. Further well designed randomized controlled trials need to be conducted. The interventions should be compared in settings where several individuals perform the venepuncture and/or the heel lance.

Treatment of neonatal pain without a gold standard: the case for caregiving interventions and sucrose administration

Although many different neonatal pain assessment scales are used in clinical research, no gold-standard instrument exists. The multitude of pain assessment scales used has, in fact, threatened the validity of many studies and confused the construct of pain. This integrative review of the neonatal pain literature provides the recommendations from practice guidelines and the current evidence for modifying the pain response prior to and during common painful procedures.

Regional anaesthetic techniques for neonatal surgery: indications and selection of techniques

The goal of neonatal care is to optimise the outcome of term and preterm infants with minimal suffering. Neonates are rare patients for the anaesthetist, therefore personal and even global experiences are limited. This chapter focuses on strategies for dealing with common clinical situations, e.g. heel lancing, obtaining vascular access, circumcision, hernia repair and pyloric stenosis, as well as major neonatal surgery. With the exception of heel lancing, regional techniques are useful in all cases. However, a careful risk-benefit analysis is mandatory, especially when considering more invasive techniques such as epidural catheters.

Foundations of knowledge about neonatal pain

This review appraises trends in the neonatal pain research literature. We searched the literature produced from 1941 to 2001. Information about the model of pain, measures of pain, design, and sample characteristics is included for each citation. Gaps in knowledge are attributed to specific conceptual and methodological problems, including the lack of basic knowledge about pain behavior, over-reliance on an invasive short-term pain model, pain measurement issues, and lack of knowledge about confounders. Ethological research methods could be used to expand basic knowledge about newborn pain.

Assessment and management of pain in infants

Infants, including newborn babies, experience pain similarly and probably more intensely than older children and adults. They are also at risk of adverse long term effects on behaviour and development, through inadequate attention towards pain relief in early life. However, the issue of analgesia in young babies has been largely neglected in most clinical settings, despite subjecting them to painful diagnostic and therapeutic procedures. Several therapeutic and preventive strategies, including systemic and local pharmacological and non-pharmacological interventions, are reported to be effective in relieving pain in infants. A judicious application of these interventions, backed by awareness and sensitivity to pain perception, on the part of the caregivers is likely to yield the best results. This article is a review of the mechanisms of pain perception, objective assessment, and management strategies of pain in infants.

Transdermal Xenobiotics in Newborn Skin

Newborn infants are regularly exposed to a wide variety of topical agents, including treatments for rashes, antimicrobial agents, solvents, and skin barriers or moisturizers. Premature and hospitalized infants are also exposed to topical iodine for antisepsis and to topical analgesic agents. The fact that most of these agents have not been specifically evaluated for use in infants has recently been recognized as a major public health concern. The epidermis of preterm infants is not fully developed, constituting an incomplete barrier to systemic absorption of topical agents. Thus, substances applied to the skin can have adverse systemic effects. Povidone-iodine and steroid creams have been associated with thyroid and hypothalamic-pituitary axis suppression, respectively, in premature infants. Application of topical EMLA (Eutectic Mixture of Local Anesthetics) for analgesia has been implicated in methemoglobinemia in premature infants. Exposure to natural latex in gloves and medical equipment may sensitize infants, leading to the development of airway hyperreactivity and other allergic manifestations. Therefore, it is advisable to limit skin exposure of premature infants to xenobiotics. Further work is required to define safe doses of common agents. In addition, transdermal administration of systemic medications, including methylxanthines, may be practical in premature infants.

Methodological considerations for the use of heart rate variability as a measure of pain reactivity in vulnerable infants

Measures of HR and HRV offer multiple indices of reactivity to painful events. These measures are particularly helpful in preterm and ill infants where distress signals are often nonspecific and ambiguous. HR is easy to acquire, and a variety of widely used techniques are available for processing it. In general, the neuroanatomic and neurophysiologic bases for pain perception are in place even in the most preterm infant and produce patterns of HR and HRV responses that are similar across multiple settings. Developmental and experiential factors related to preterm birth, however, may affect these HR responses. Furthermore, evaluation of ill infants in an NICU setting adds multiple contextual factors that potentially influence HR and HRV and alter their specificity as measures of pain. In some cases, it may appear that pain reactivity is reduced when, in fact, HR reactivity is only an expression of the biologic capacity to produce a response, not the presence of a response itself. The nature of the setting and the infant's health, developmental stage, and behavioral state all contribute to potentially altering HR responses to painful events in this setting. Thus, the methodology used and its application must be flexible. A variety of HRV analysis techniques may be needed to identify a variety of response patterns and mechanisms that influence pain reactivity. Furthermore, careful selection of HR epochs for stationarity, an understanding of the potential discordance between biologic and behavioral measures, the effects of medication, and an accounting for developmental differences that occur during a typical NICU course are all critical factors for investigators to be aware of. Understanding cardiovascular reactivity as a measure of response to painful events in vulnerable infants requires ongoing work.

Effect of multisensory stimulation on analgesia in term neonates: a randomized controlled trial

Many attempts have been made to obtain safe and effective analgesia in newborns. Oral glucose-water has been found to have analgesic properties in neonates. We investigated whether other sensory stimulation added to oral glucose provided more effective analgesia than oral glucose alone. In a randomized prospective double-blind trial, we studied 120 term newborns during heel prick. The babies were divided randomly into six groups of 20, and each group was treated with a different procedure during heel prick: A) control; B) 1 mL 33% oral glucose given 2 min before the heel prick; C) sucking; D) 1 mL 33% oral glucose plus sucking; E) multisensory stimulation including 1 mL 33% oral glucose (sensorial saturation); F) multisensory stimulation without oral glucose. Sensorial saturation consisted in massage, voice, eye contact, and perfume smelling during heel prick. Each heel prick was filmed and assigned a point score according to the Douleur Aiguë du Nouveau-né (DAN) neonatal acute pain scale. Camera recording began 30 s before the heel prick, so it was impossible for the scorers to distinguish procedure A (control) from B (glucose given 2 min before), C (sucking water) from D (sucking glucose), and E (multisensory stimulation and glucose) from F (multisensory stimulation and water) from the video. Procedure E (multisensory stimulation and glucose) was found to be the most effective procedure, and the analgesia was even more effective than that produced by procedure D (sucking glucose). We conclude that sensorial saturation is an effective analgesic technique that potentiates the analgesic effect of oral sugar. It can be used for minor painful procedures on newborns.

Assessment and management of pain in neonates

Neonates are capable of experiencing pain from birth onwards. An impressive body of neuroanatomical, neurochemical and biobehavioural evidence, which has accumulated over the past 2 decades, supports this capability. This evidence mandates health professionals to attend to the prevention, elimination, or at the very least, control of pain for infants. This mandate is essential since pain is known to have both immediate and long term effects, especially if pain is untreated and is severe, prolonged or frequently experienced. Therefore, pain must be assessed frequently, not only to measure location, intensity and duration but also to determine the effectiveness of interventions implemented to control pain. An impressive array of measures for assessing acute pain in infants exists which incorporates valid pain indicators in this population. However, there is a need to develop new measures to assess chronic pain conditions and pain in infants in acute situations.

Sucrose analgesia for minor procedures in newborn infants

OBJECTIVE

To evaluate the role of intraoral sucrose and other sweet-tasting solutions for the management of pain associated with minor procedures in newborns.

DATA SOURCES

A search of MEDLINE articles from 1966 to August 1999 and an extensive review of journals was conducted. MeSH headings included analgesia, sucrose, and neonate.

DATA SYNTHESIS

Newborn infants regularly undergo minor invasive procedures for which analgesics are not routinely used. Intraoral sucrose and other sweet-tasting solutions appear to diminish surrogate biomarkers of pain response as evidenced by a reduction in crying time, smaller increases in heart rate, and lower pain scale ratings.

CONCLUSIONS

These studies appear to suggest that sucrose solution 0.5 g provides effective analgesia with no reported adverse effects.

No more tears: a randomized controlled double-blind trial of Amethocaine gel vs. placebo in the management of procedural pain in neonates

AIM

During a comparative double-blind study, the efficacy of Amethocaine local anaesthetic gel was compared with that of a placebo gel to establish their effect on the reduction of behavioural and physiological responses to pain in neonates.

METHOD

Forty infants were included in the trial, 20 being randomly assigned to each group. After topical application of either Amethocaine or the placebo for 30 minutes, cannulation was performed using a 24 gauge cannula. Assessment of pain was made with the aid of four point assessment tool incorporating facial expression, cry and heart rate changes and ease of cannulation. Additional baseline data were obtained including sex, gestation, weight and previous experience of cannulation, and analysed using Statistical Package for Social Sciences (SPSS).

RESULTS

Good analgesic effects were demonstrated in the Amethocaine group, as there was a high level of significance (P < 0.01) in the difference in pain scores between the two groups using a Mann-Whitney U-test. There was no correlation between gestation or weight and the degree of pain experienced during painful procedures. No significant relationship was found between cannulation and the degree of pain experienced.

CONCLUSION

It can, therefore, be concluded that Amethocaine gel is an effective local anaesthetic in the management of skin puncturing procedural pain in neonates, and that all infants regardless of maturity, weight or previous experiences probably experience a similar degree of pain and therefore warrant effective and appropriate analgesic intervention.

Capillary blood sampling: the pain of single-use lancing devices

Six disposable automatic lancing devices were examined in 50 healthy adult volunteers with regard to pain intensity, blood volume and user safety. Devices with a trigger-linked lancet movement were significantly more painful than those with a preset lancet speed. Residual pain was more frequent after the use of devices with a blade compared to devices with a needle. Only half of the devices reliably produced sufficient blood volumes (> 50 microl). Two of the devices could accidentally be re-used and constitute a hazard for patient and personnel. It is concluded that some of the disposable automatic lancing devices are safe and reliable but none of them causes minimal pain.

Topical amethocaine gel for pain relief of heel prick blood sampling: a randomised double blind controlled trial

BACKGROUND

Heel prick blood sampling is a commonly performed and painful procedure in the newborn infant. Use of a topical local anaesthetic does not relieve this pain. A 4% w/w amethocaine gel (Ametop) reduces the pain of venepuncture in the newborn but has not been tried with heel pricks.

AIM

To investigate the effect of topical amethocaine gel on the pain of heel prick in the newborn infant.

DESIGN

Randomised, double blind, placebo controlled trial.

SUBJECTS

Sixty newborn infants, gestation 28-42 weeks (median 36), postnatal age 1-16 days (median 5) undergoing routine heel prick blood sampling.

METHODS

A 1.5 g portion of 4% w/w amethocaine gel or placebo was applied to the skin under occlusion for one hour, then wiped away. Heel prick blood sampling with a spring loaded lance was performed five minutes later. The procedure was videotaped and pain assessed at one second intervals using an adaptation of the neonatal facial coding system (NFCS). No or minimal pain was defined as a cumulative score of less than 5 (out of 15) in the three seconds after firing of the lance and as lack of a cry in the first five seconds.

RESULTS

In terms of a low NFCS core and lack of cry (p = 0.12) 20 of 30 (67%) in the amethocaine group and 13 of 29 (45%) in the placebo group had no or minimal pain in response to the heel prick. The median cumulative NFCS score over the three seconds after firing the lance was 3 (interquartile range 0-6) in the amethocaine group compared with 5 (interquartile range 1-10) in the placebo group (p = 0.07). These differences are not significant.

CONCLUSIONS

Topical amethocaine gel does not have a clinically important effect on the pain of heel prick blood sampling and its use for this purpose cannot therefore be recommended. Alternative approaches to the relief of pain from this procedure should be explored.

Treatment of pain in the neonatal intensive care unit

Pain is a disruptive influence on infants in the NICU. The most obvious and effective strategy to decrease infant pain in the NICU is to stringently limit the frequency of painful procedures, especially those that are most commonly reported (i.e., heel lances and endotracheal suctioning), and have these performed on infants that are most unstable or critically ill by the most experienced person available. Organizational concerns over the cost of NICU care have forced a re-evaluation of the necessity of certain diagnostic and care procedures and a limiting of procedures to those that can be documented to positively affect clinical outcome. Pharmacologic and nonpharmacologic strategies are essential to the prevention and management of neonatal pain, and these should be considered for complementary use for every infant. Research has shown the safety and effectiveness of some of the strategies in reducing mild pain caused by brief invasive procedures; however, many of the studies had methodologic limitations. Therefore, more research is required to determine the comparative efficacy of the various strategies and to document additive or synergistic effects when combined.

Topical use of local anesthetics in neonates

INTRODUCTION

Various local anesthetics as in lidocaine ointment, amethocaine cream and EMLA cream are used topically for minor invasive interventions, such as venipuncture, both in children and adults. Since neonates have a nervous system that, albeit immature, enables them to feel pain, analgesia for these procedures is also indicated. Several studies in neonates have been carried out to establish effectiveness and safety of topically applied local anesthetics. These studies are reviewed in order to assess effectiveness and safety.

METHODS

A Medline search was made in order to review all studies on effectiveness and safety of topical use of local anesthetics in neonates. Effectivity or safety studies using local anesthetics for circumcision were rejected.

RESULTS

Seven studies on effectiveness were found: Three studies examined lidocaine ointment and four examined EMLA cream. Effectiveness of lidocaine ointment was questionable in two studies and negative in one. Effectiveness of EMLA cream was positive in two studies and negative in the other two. Four studies were found on safety of EMLA cream. All studies indicated that use of EMLA cream was safe.

DISCUSSION

The poor effectiveness found in the reviewed studies is possibly due to too long an application time, a lipophilic carrier used and difficulties in assessing pain. The time of application is often based upon studies in children. Since the skin of neonates acts more as a mucosa than as mature skin the local anesthetics are able to cross this barrier more rapidly. Also a high bloodflow in the heel enhances the uptake of the drug. The application time in neonates should therefore be reduced compared to children. The use of a lipophilic carrier should be avoided since a lipophilic carrier impedes the local anesthetic to be absorbed, leading to reduced effect. Various methods of pain assessment were being used. Since not all methods used are validated it is difficult to obtain an objective end point.

CONCLUSION AND RECOMMENDATION

The articles reviewed are non conclusive in their results of effective analgesia. Due to a lipophilic base form and a hydrophilic matrix EMLA cream is most effective. An application time of 30 minutes is recommended. In spite of the present precautions due to fear of methemoglobinemia, use of EMLA cream proved to be safe when used once a day. Since the clinical situation often requires more than one application a day, more research is needed to establish a safe and effective local anesthetic which can be applied topically several times a day in the neonate.

Ultrasound study of heel to calcaneum depth in neonates

AIM

To investigate whether it would be safe to extend the currently recommended area of sampling to the whole heel in neonates.

METHODS

Eighty newborn infants were studied, weight range 0.56 to 4.34 kg, gestation 24 to 42 weeks. Ultrasound scanning was used to measure the shortest distance between the skin and the perichondrium of the calcaneum.

RESULTS

The shortest depth of perichondrium was in the centre of the heel and ranged from 3 to 8 mm. In 78 of the 80 infants the distance was 4 mm or more. There was a small but significant positive correlation with weight.

CONCLUSIONS

Standard automated lancets for preterm use that puncture to a depth of 2.4 mm may be safely used anywhere over the plantar surface of the heel. The posterior aspect of the heel should be avoided. Reducing the density of heel pricks should reduce the associated pain.

Environmental and behavioral strategies to prevent and manage neonatal pain

This article provides an overview of environmental and behavioral methods for pain management in newborn infants. Specific interventions in the areas of containing, positioning, nonpainful sensory stimuli, non-nutritive sucking, sucrose, and procedural technique are discussed. The conceptual framework and research evidence for the efficacy of these methods are examined. Opportunities for further research to evaluate the comparative efficacy of environmental and behavioral pain interventions are emphasized.

Practical approach to analgesia and sedation in the neonatal intensive care unit

The anatomic and physiological bases for nociception are present even in very preterm neonates. Neonates show the same behavioral, endocrine, and metabolic responses to noxious stimuli as older subjects. Preterm infants appear to be more sensitive to painful stimuli and have heightened responses to successive stimuli. Infants receiving intensive care are subjected to frequent stressful procedures and also chronic noxious influences related to the environment of care. Inflammatory conditions such as necrotizing enterocolitis may also cause pain. Untreated pain in babies is associated with increased major morbidity and mortality. Nonpharmacological interventions, including environmental modification and comforting during procedures reduce stress. Intravenous opiates are the mainstay of pharmacological analgesia. A pure sedative agent can provide physiological stability in settings in which there are less acutely painful stimuli or when there are adverse effects from, or tolerance to, opiates. Local anesthesia of skin and mucous membranes is helpful for invasive procedures. Antipyretic analgesics such as acetaminophen have a role in inflammatory pain.

Venipuncture is more effective and less painful than heel lancing for blood tests in neonates

OBJECTIVE

Heel lancing has hitherto been the method of choice for screening tests of inborn errors of metabolism in neonates. Eutectic mixture of local anesthetic has little, if any, analgesic effect when applied to the heel of pre- and full-term infants. Today there seems to be no practical method that effectively alleviates the pain caused by heel lancing. The aim of this study was to investigate whether other methods, such as venipuncture of the dorsal side of the hand, are less painful and more efficient than heel lancing in neonates.

METHODS

One hundred twenty healthy, full-term infants who underwent testing for phenylketonuria (PKU) were included in the study. They were randomized into three groups: a venipuncture group (VP) (n = 50), a heel-lance group with a small lancet (SL) (n = 50), or a large lancet (LL) (n = 20). Pain reactions were assessed by the Neonatal Facial Coding System (NFCS). The latency and duration of the first cry as well as the total screaming time was analyzed. The efficacy of the method was assessed by the time taken to complete the PKU test and number of times the skin had to be punctured.

RESULTS

Nociceptive response. The NFCS scores after the first skin puncture were: VP, 247; SL, 333; and LL, 460. The NFCS scores were significantly lower in the VP than in the groups subjected to heel lancing. During the first 60 seconds after skin puncture, 44% of the infants cried in the VP group, compared with 72% and 85% in the SL and LL groups, respectively. Efficacy. A successful PKU test with only one skin puncture was performed in 86% of the VP group, but in only 19% in the SL group and 40% in the LL group. The total time needed to obtain the PKU blood sample was 191 seconds (median) in the VP group, 419 seconds in the SL group, and 279 seconds in the LL group.

CONCLUSION

Venipuncture is more effective and less painful than heel lancing for blood tests in neonates.

Randomised controlled trial of eutectic mixture of local anaesthetics cream for venepuncture in healthy preterm infants

AIM

To assess the safety and efficacy of EMLA cream (eutectic mixture of local anaesthetics) used to induce surface anaesthesia for venepuncture in healthy preterm infants.

METHODS

Nineteen infants, median gestational age 31 weeks (range 26-33 weeks) were assessed in a randomised, double blind, placebo controlled, cross-over trial. Changes in physiological variables (heart rate, blood pressure, oxygen saturation) and behavioural responses (neonatal facial coding system score, crying time) before and after venepuncture with EMLA cream were compared with those obtained with a placebo cream to assess efficacy. Toxicity was assessed by comparing methaemoglobin concentrations at 1 hour and 8 hours after application.

RESULTS

There was no significant difference in efficacy between EMLA and placebo creams in physiological and behavioural responses. There was no significant difference in methaemoglobin concentrations one hour after the cream had been applied. At eight hours, however, concentrations were significantly higher after EMLA than placebo (p = 0.016). There was no evidence of clinical toxicity.

CONCLUSION

This study does not support the routine use of EMLA for venepuncture in healthy preterm infants.

A systematic review of lidocaine-prilocaine cream (EMLA) in the treatment of acute pain in neonates

OBJECTIVE

Neonates routinely undergo painful cutaneous procedures as part of their medical treatment. Lidocaine-prilocaine 5% cream (EMLA) is a topical anesthetic that may be useful for diminishing the pain from these procedures. EMLA is routinely used in children and adults. There is substantial apprehension about its use in neonates because of concerns that it may cause methemoglobinemia. The objective of this review was to determine the efficacy and safety of EMLA as an analgesic for procedural pain treatment in neonates and provide evidence-based recommendations for clinical practice.

METHODS

Systematic review techniques were used. Studies were identified using manual and computer-aided searches (Medline, EMBASE, Reference Update, personal files, scientific meeting proceedings). Behavioral (eg, facial action, crying) and physiologic (eg, heart rate, oxygen saturation, blood pressure, respiratory rate) outcome data from prospective nonrandomized controlled studies and randomized controlled trials in full-term and preterm neonates were accepted for inclusion to establish efficacy of EMLA. The risk of methemoglobinemia (defined as methemoglobin concentration >5% and requiring medical intervention) was estimated from all prospective studies.

RESULTS

Eleven studies of the efficacy of EMLA were included in the analysis. Infant gestational age at the time of delivery ranged from 26 weeks to full-term. Two studies included data from both neonates and older infants. The following procedures were studied: circumcision (n = 3), heel lancing (n = 4), venipuncture (n = 1), venipuncture and arterial puncture (n = 1), lumbar puncture (n = 1), and percutaneous venous catheter placement (n = 1). Nine studies were randomized controlled trials. The total sample size for each study ranged from 13 to 110 neonates. The dose of EMLA used was 0.5 g to 2 g in 9 studies, and was not specified in the others. The duration of application ranged from 10 minutes to 3 hours. The three studies that investigated the efficacy of EMLA for decreasing the pain of circumcision used a randomized controlled trial design. All of them demonstrated significantly reduced crying time during the procedure in the infants in the EMLA group compared with the infants in the control group. Facial grimacing, assessed in two of the studies, was also significantly lower in the EMLA group. Using meta-analytic techniques, the heart rate outcome data for two studies was summarized. Increases in heart rate compared with baseline values were 12 to 27 beats per minute less for the EMLA group than in the placebo group during various stages of the surgical procedure. Three studies that investigated the pain from heel lancing were randomized controlled trials; the other was a nonrandomized controlled study. None demonstrated a significant benefit of EMLA for any of the outcome measures used to assess pain (ie, behavioral pain scores, infant crying, heart rate, blood pressure, respiratory rate, oxygenation parameters). One randomized controlled study of the pain from venipuncture showed that infants treated with EMLA had significantly lower heart rates and cry duration compared with infants treated with a placebo. In one nonrandomized study, a significantly lower behavioral pain score was observed for infants treated with EMLA compared with the control group. Infant heart rate, however, did not differ between the groups. In one randomized controlled study of pain from percutaneous venous catheter placement, EMLA resulted in a significantly lower increase in heart rate and respiratory rate. Behavioral pain scores were significantly lower during arterial puncture in one nonrandomized controlled study. EMLA did not reduce physiologic changes or behavioral pain scores in one randomized controlled trial in infants undergoing lumbar puncture. Meta-analytic techniques revealed that methemoglobin concentrations did not differ between EMLA-treated and placebo-treated infants (weighted mean di

Pharmacologic pain management in children: a review of intervention research

In the past decade, an explosion of interest in pediatric pain has resulted in the proliferation of research studies. This review examines 41 studies that focus on pharmacologic interventions in children during the last decade. Criteria for inclusion in this paper were studies that (1) tested a pharmacological intervention prospectively, (2) were conducted with children only, (3) had a sample size over 30, (4) randomly assigned participants to two or more groups, and (5) provided sufficient methodological and statistical detail for critique. Studies focused on postoperative and procedural pain, were conducted most frequently with pre-school-aged children or older, and demonstrated the efficacy of pharmacologic interventions.