Oral sucrose as an analgesic drug for procedural pain in newborn infants: a randomised controlled trial

Effect of Vibration on Pain Response to Heel Lance: A Pilot Randomized Control Trial

BACKGROUND

Applied mechanical vibration in pediatric and adult populations has been shown to be an effective analgesic for acute and chronic pain, including needle pain. Studies among the neonatal population are lacking. According to the Gate Control Theory, it is expected that applied mechanical vibration will have a summative effect with standard nonpharmacologic pain control strategies, reducing behavioral and physiologic pain responses to heel lancing.

PURPOSE

To determine the safety and efficacy of mechanical vibration for relief of heel lance pain among neonates.

METHODS

In this parallel design randomized controlled trial, eligible enrolled term or term-corrected neonates (n = 56) in a level IV neonatal intensive care unit were randomized to receive either sucrose and swaddling or sucrose, swaddling, and vibration for heel lance analgesia. Vibration was applied using a handheld battery-powered vibrator (Norco MiniVibrator, Hz = 92) to the lateral aspect of the lower leg along the sural dermatome throughout the heel lance procedure. Neonatal Pain, Agitation, and Sedation Scale (N-PASS) scores, heart rate, and oxygen saturations were collected at defined intervals surrounding heel lancing.

RESULTS

Infants in the vibration group (n = 30) had significantly lower N-PASS scores and more stable heart rates during heel stick (P = .006, P = .037) and 2 minutes after heel lance (P = .002, P = .016) than those in the nonvibration group. There were no adverse behavioral or physiologic responses to applied vibration in the sample.

IMPLICATIONS FOR PRACTICE AND RESEARCH

Applied mechanical vibration is a safe and effective method for managing heel lance pain. This pilot study suggests that mechanical vibration warrants further exploration as a nonpharmacologic pain management tool among the neonatal population.

A blinded randomised placebo-controlled trial investigating the efficacy of morphine analgesia for procedural pain in infants: Trial protocol

Infant pain has both immediate and long-term negative consequences, yet in clinical practice it is often undertreated. To date, few pain-relieving drugs have been tested in infants. Morphine is a potent analgesic that provides effective pain relief in adults, but there is inconclusive evidence for its effectiveness in infants. The purpose of this study is to establish whether oral morphine provides effective analgesia for procedural pain in infants. A blinded, placebo-controlled, parallel-group randomized, phase II, clinical trial will be undertaken to determine whether morphine sulphate administered orally prior to clinically-required retinopathy of prematurity (ROP) screening and heel lancing provides effective analgesia. 
156 infants between 34 and 42 weeks' gestational age who require a clinical heel lance and ROP screening on the same test occasion will be included in the trial. Infants will be randomised to receive either a single dose of morphine sulphate (100 μg/kg) or placebo. Each infant will be monitored for 48 hours and safety data will be collected during the 24 hours following drug administration. The primary outcome will be the Premature Infant Pain Profile-revised (PIPP-R) score 30 seconds after ROP screening. The co-primary outcome will be the magnitude of nociceptive-specific brain activity evoked by a clinically-required heel lance. Infant clinical stability will be assessed by comparing the number of episodes of bradycardia, tachycardia, desaturation and apnoea, and changes in respiratory support requirements in the 24-hour periods before and after the clinical intervention. In addition, drug safety will be assessed by considering the occurrence of apnoeic and hypotensive episodes requiring intervention in the 24-hour period following drug administration. This study has been published as an Accepted Protocol Summary by The Lancet.

A blinded randomised placebo-controlled trial investigating the efficacy of morphine analgesia for procedural pain in infants: Trial protocol

Infant pain has both immediate and long-term negative consequences, yet in clinical practice it is often undertreated. To date, few pain-relieving drugs have been tested in infants. Morphine is a potent analgesic that provides effective pain relief in adults, but there is inconclusive evidence for its effectiveness in infants. The purpose of this study is to establish whether oral morphine provides effective analgesia for procedural pain in infants. A blinded, placebo-controlled, parallel-group randomized, phase II, clinical trial will be undertaken to determine whether morphine sulphate administered orally prior to clinically-required retinopathy of prematurity (ROP) screening and heel lancing provides effective analgesia. 
156 infants between 34 and 42 weeks' gestational age who require a clinical heel lance and ROP screening on the same test occasion will be included in the trial. Infants will be randomised to receive either a single dose of morphine sulphate (100 μg/kg) or placebo. Each infant will be monitored for 48 hours and safety data will be collected during the 24 hours following drug administration. The primary outcome will be the Premature Infant Pain Profile-revised (PIPP-R) score 30 seconds after ROP screening. The co-primary outcome will be the magnitude of nociceptive-specific brain activity evoked by a clinically-required heel lance. Infant clinical stability will be assessed by comparing the number of episodes of bradycardia, tachycardia, desaturation and apnoea, and changes in respiratory support requirements in the 24-hour periods before and after the clinical intervention. In addition, drug safety will be assessed by considering the occurrence of apnoeic and hypotensive episodes requiring intervention in the 24-hour period following drug administration. This study has been published as an Accepted Protocol Summary by The Lancet.

Paracetamol and morphine for infant and neonatal pain; still a long way to go?

INTRODUCTION

Pharmacologic pain management in newborns and infants is often based on limited scientific data. To close the knowledge gap, drug-related research in this population is increasingly supported by the authorities, but remains very challenging. This review summarizes the challenges of analgesic studies in newborns and infants on morphine and paracetamol (acetaminophen). Areas covered: Aspects such as the definition and multimodal character of pain are reflected to newborn infants. Specific problems addressed include defining pharmacodynamic endpoints, performing clinical trials in this population and assessing developmental changes in both pharmacokinetics and pharmacodynamics. Expert commentary: Neonatal and infant pain management research faces two major challenges: lack of clear biomarkers and very heterogeneous pharmacokinetics and pharmacodynamics of analgesics. There is a clear call for integral research addressing the multimodality of pain in this population and further developing population pharmacokinetic models towards physiology-based models.

What do we really know about newborn infant pain?

NEW FINDINGS

What is the topic of this review? Pain in infancy. What advances does it highlight? New neurophysiological research on pain processing in the human infant brain. Increased awareness of pain in the newborn has led to the development of numerous assessment tools for use in neonatal intensive care units. Here, I argue that we still know too little about the neurophysiological basis for infant pain to interpret data from clinical observational measures. With increased understanding of how the neural activity and CNS connections that underlie pain behaviour and perception develop in the newborn will come better measurement and treatment of their pain. This review focuses upon two interconnected nociceptive circuits, the spinal cord dorsal horn and the somatosensory cortex in the brain, to highlight what we know and what we do not know about infant pain. The effectiveness of oral sucrose, widely used in clinical practice to relieve infant pain, is discussed as a specific example of what we do not know. This 'hot topic review' highlights the importance of new laboratory-based neurophysiological research for the treatment of newborn infant pain.

Sucrose for analgesia in newborn infants undergoing painful procedures

BACKGROUND

Administration of oral sucrose with and without non-nutritive sucking is the most frequently studied non-pharmacological intervention for procedural pain relief in neonates.

OBJECTIVES

To determine the efficacy, effect of dose, method of administration and safety of sucrose for relieving procedural pain in neonates as assessed by validated composite pain scores, physiological pain indicators (heart rate, respiratory rate, saturation of peripheral oxygen in the blood, transcutaneous oxygen and carbon dioxide (gas exchange measured across the skin - TcpO2, TcpCO2), near infrared spectroscopy (NIRS), electroencephalogram (EEG), or behavioural pain indicators (cry duration, proportion of time crying, proportion of time facial actions (e.g. grimace) are present), or a combination of these and long-term neurodevelopmental outcomes.

SEARCH METHODS

We used the standard methods of the Cochrane Neonatal. We performed electronic and manual literature searches in February 2016 for published randomised controlled trials (RCTs) in the Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library, Issue 1, 2016), MEDLINE (1950 to 2016), EMBASE (1980 to 2016), and CINAHL (1982 to 2016). We did not impose language restrictions.

SELECTION CRITERIA

RCTs in which term or preterm neonates (postnatal age maximum of 28 days after reaching 40 weeks' postmenstrual age), or both, received sucrose for procedural pain. Control interventions included no treatment, water, glucose, breast milk, breastfeeding, local anaesthetic, pacifier, positioning/containing or acupuncture.

DATA COLLECTION AND ANALYSIS

Our main outcome measures were composite pain scores (including a combination of behavioural, physiological and contextual indicators). Secondary outcomes included separate physiological and behavioural pain indicators. We reported a mean difference (MD) or weighted MD (WMD) with 95% confidence intervals (CI) using the fixed-effect model for continuous outcome measures. For categorical data we used risk ratio (RR) and risk difference. We assessed heterogeneity by the I(2) test. We assessed the risk of bias of included trials using the Cochrane 'Risk of bias' tool, and assessed the quality of the evidence using the GRADE system.

MAIN RESULTS

Seventy-four studies enrolling 7049 infants were included. Results from only a few studies could be combined in meta-analyses and for most analyses the GRADE assessments indicated low- or moderate-quality evidence. There was high-quality evidence for the beneficial effect of sucrose (24%) with non-nutritive sucking (pacifier dipped in sucrose) or 0.5 mL of sucrose orally in preterm and term infants: Premature Infant Pain Profile (PIPP) 30 s after heel lance WMD -1.70 (95% CI -2.13 to -1.26; I(2) = 0% (no heterogeneity); 3 studies, n = 278); PIPP 60 s after heel lance WMD -2.14 (95% CI -3.34 to -0.94; I(2) = 0% (no heterogeneity; 2 studies, n = 164). There was high-quality evidence for the use of 2 mL 24% sucrose prior to venipuncture: PIPP during venipuncture WMD -2.79 (95% CI -3.76 to -1.83; I(2) = 0% (no heterogeneity; 2 groups in 1 study, n = 213); and intramuscular injections: PIPP during intramuscular injection WMD -1.05 (95% CI -1.98 to -0.12; I(2) = 0% (2 groups in 1 study, n = 232). Evidence from studies that could not be included in RevMan-analyses supported these findings. Reported adverse effects were minor and similar in the sucrose and control groups. Sucrose is not effective in reducing pain from circumcision. The effectiveness of sucrose for reducing pain/stress from other interventions such as arterial puncture, subcutaneous injection, insertion of nasogastric or orogastric tubes, bladder catherization, eye examinations and echocardiography examinations are inconclusive. Most trials indicated some benefit of sucrose use but that the evidence for other painful procedures is of lower quality as it is based on few studies of small sample sizes. The effects of sucrose on long-term neurodevelopmental outcomes are unknown.

AUTHORS' CONCLUSIONS

Sucrose is effective for reducing procedural pain from single events such as heel lance, venipuncture and intramuscular injection in both preterm and term infants. No serious side effects or harms have been documented with this intervention. We could not identify an optimal dose due to inconsistency in effective sucrose dosage among studies. Further investigation of repeated administration of sucrose in neonates is needed. There is some moderate-quality evidence that sucrose in combination with other non-pharmacological interventions such as non-nutritive sucking is more effective than sucrose alone, but more research of this and sucrose in combination with pharmacological interventions is needed. Sucrose use in extremely preterm, unstable, ventilated (or a combination of these) neonates needs to be addressed. Additional research is needed to determine the minimally effective dose of sucrose during a single painful procedure and the effect of repeated sucrose administration on immediate (pain intensity) and long-term (neurodevelopmental) outcomes.

The validity and reliability of the EValuation of INtervention Scale: preliminary report

AIM

Pain management is a priority for infants receiving neonatal care as they undergo many necessary painful and stressful interventions, which are associated with negative short- or long-term consequences. This study aims to validate the content, and test the reliability, of the EValuation of INtervention Scale (EVIN), which is designed to evaluate the use of widely recommended nonpharmacological strategies to reduce neonatal pain and stress during procedures.

METHODS

The content of the EVIN was validated with multidisciplinary participation (N = 80), and consistency was established via observations on preterm infants (N = 12, at 31-34 weeks' gestation) during interventions in a neonatal unit. A revised scale was tested for inter-rater reliability with observations of invasive (blood sampling, N = 16) and noninvasive (nappy change, N = 18) interventions. The intraclass correlation coefficient (ICC) was used to determine inter-rater reliability. SPSS (PASW Statistics) version 18 was used for analysis.

RESULTS

Very good intraclass correlation coefficients (>0.8) for both invasive (0.962) and noninvasive procedures (0.970) were achieved.

CONCLUSION

These results indicate that the EVIN is suitable for the evaluation of nonpharmacological support during painful or stressful interventions.

Neonatal pain and reduced maternal care: Early-life stressors interacting to impact brain and behavioral development

Advances in neonatal intensive care units (NICUs) have drastically increased the survival chances of preterm infants. However, preterm infants are still exposed to a wide range of stressors during their stay in the NICU, which include painful procedures and reduced maternal contact. The activation of the hypothalamic-pituitary-adrenal (HPA) axis, in response to these stressors during this critical period of brain development, has been associated with many acute and long-term adverse biobehavioral outcomes. Recent research has shown that Kangaroo care, a non-pharmacological analgesic based on increased skin-to-skin contact between the neonate and the mother, negates the adverse outcomes associated with neonatal pain and reduced maternal care, however the biological mechanism remains widely unknown. This review summarizes findings from both human and rodent literature investigating neonatal pain and reduced maternal care independently, primarily focusing on the role of the HPA axis and biobehavioral outcomes. The physiological and positive outcomes of Kangaroo care will also be discussed in terms of how dampening of the HPA axis response to neonatal pain and increased maternal care may account for positive outcomes associated with Kangaroo care.

Development of Cardiovascular Indices of Acute Pain Responding in Infants: A Systematic Review

Background. Cardiovascular indices of pain are pervasive in the hospital setting. However, no prospective research has examined the development of cardiac responses to acutely painful procedures in the first year of life. Objectives. Our main goal was to synthesize existing evidence regarding the development of cardiovascular responses to acutely painful medical procedures over the first year of life in preterm and term born infants. Methods. A systematic search retrieved 6994 articles to review against inclusion criteria. A total of 41 studies were included in the review. Results. In response to acutely painful procedures, most infants had an increase in mean heart rate (HR) that varied in magnitude both across and within gestational and postnatal ages. Research in the area of HR variability has been inconsistent, limiting conclusions. Conclusions. Longitudinal research is needed to further understand the inherent variability of cardiovascular pain responses across and within gestational and postnatal ages and the causes for the variability.

Effect of change in sequence of administration of DTwP and Hepatitis B vaccines on perception of pain in infants: A randomized control trial

OBJECTIVE

This study was designed with objective to study pain response of infants to change in sequence of administration of Hepatitis B and DTwP vaccines.

METHODS

This was a randomized parallel control trial. The study was carried out in the immunization clinic of the Department of Pediatrics, LLRM Medical College, Meerut. One hundred and thirty healthy term infants up to 4 months of age were injected either DTwP vaccine first or Hepatitis B vaccine first, followed one minute later by the other vaccine.

RESULT

Baseline characteristics did not differ between the groups. The mean (SD) of AUC of MFCS and NIPS was significantly more in DF group as compared to HF group (for MFCS 25.5 ± 5.4 versus 22.5 ± 5.5, p<0.01; for NIPS 31.77 ± 5.5 versus 27.64 ± 6.9, p < 0.01). Similarly mean (SD) of AUC of Heart rate and saturation of oxygen showed significant variation in DF group as compared to HF group (for heart rate 591.6 ± 55 versus 559.6 ± 49, p< 0.01; for SpO2 326.4 ± 12 versus 335 ± 8, p < 0.01).

CONCLUSION

These results showed that infant experienced lesser pain when Hepatitis B was administered first than when DTwP vaccine was given first.

Oral Sucrose for Pain in Neonates During Echocardiography: A Randomized Controlled Trial

OBJECTIVE

To test the efficacy of oral sucrose in reducing pain/stress during echocardiography as estimated by Premature Infant Pain Profile score.

DESIGN

Double-blind, parallel-group, randomized control trial.

SETTING

Tertiary-care neonatal care unit located in Western India.

PARTICIPANTS

Neonates with established enteral feeding, not on any respiratory support and with gestational age between 32 and 42 weeks requiring echocardiography.

INTERVENTIONS

Neonates in intervention group received oral sucrose prior to echocardiography.

MAIN OUTCOME MEASURES

Assessment was done using Premature Infant Pain Profile score.

RESULTS

There were 104 examinations; 52 in each group. Baseline characteristics like mean gestational age (37.6 vs. 37.1), birth weight (2.20 vs. 2.08), and feeding status (Breastfeeding- 59.6% vs. 44.2%, paladai feeding- 13.5% vs. 13.5%, and gavage feeding- 26.9% vs. 42.3%) were comparable. The mean (SD) premature infant pain profile score was significantly higher in control group [(7.4 (3.78) vs. 5.2 (1.92), P <0.001].

CONCLUSION

Oral sucrose significantly reduces pain, and is safe to administer to neonates.

Prevention and Management of Procedural Pain in the Neonate: An Update

The prevention of pain in neonates should be the goal of all pediatricians and health care professionals who work with neonates, not only because it is ethical but also because repeated painful exposures have the potential for deleterious consequences. Neonates at greatest risk of neurodevelopmental impairment as a result of preterm birth (ie, the smallest and sickest) are also those most likely to be exposed to the greatest number of painful stimuli in the NICU. Although there are major gaps in knowledge regarding the most effective way to prevent and relieve pain in neonates, proven and safe therapies are currently underused for routine minor, yet painful procedures. Therefore, every health care facility caring for neonates should implement (1) a pain-prevention program that includes strategies for minimizing the number of painful procedures performed and (2) a pain assessment and management plan that includes routine assessment of pain, pharmacologic and nonpharmacologic therapies for the prevention of pain associated with routine minor procedures, and measures for minimizing pain associated with surgery and other major procedures.

Randomized placebo-controlled trial of sucrose analgesia on neonatal skin blood flow and pain response during heel lance

OBJECTIVES

To evaluate the effect of oral sucrose on skin blood flow (SBF; perfusion units; PU) measured by Laser Doppler Imager (LDI) in term newborns and pain response (Neonatal Infant Pain Scale score; NIPS score) during heel lance; (2) determine SBF changes during heel lance; and (3) the relationship between SBF and NIPS.

MATERIALS AND METHODS

Term infants ≤7 days old (n=56) undergoing routine heel lance were randomized to pretreatment with 2.0 mL oral 24% sucrose (n=29) or sterile water (n=27) in a double-blinded, placebo-controlled trial. SBF was assessed by LDI scans and NIPS scores at 10 minutes before lance, immediately after lancing, and 5 minutes after blood extraction. Mean SBF and median NIPS scores were compared between groups using General Linear Model or Kruskal-Wallis. Regressions examined the relationship between SBF immediately after heel lance and NIPS score.

RESULTS

Mean SBF and median NIPS scores immediately after heel lance were lower in sucrose-treated infants (167.9±15.5 vs. 205.4±16.0 PU, P=0.09; NIPS 1 [interquartile range 0 to 4] vs. NIPS 3 [interquartile range 0 to 6], P=0.02), although no significant difference in mean SBF. During heel lance NIPS score was predictive of SBF. An increase of 1 in NIPS score was associated with 11 PU increase in SBF (R=0.21; P=0.09) for sucrose, and 16 PU increase for placebo-treated infants (R=0.20; P=0.014).

CONCLUSIONS

Increased SBF assessed by LDI is a pain response among term neonates after routine heel lance, which was not completely attenuated by oral sucrose administration. Increased SBF is associated with NIPS scores. Sucrose analgesic efficacy evidenced by decreased NIPS scores for the sucrose group. Association of SBF with NIPS scores suggests that LDI is potentially useful for assessing newborn procedural pain.

Non-pharmacological management of infant and young child procedural pain

BACKGROUND

Infant acute pain and distress is commonplace. Infancy is a period of exponential development. Unrelieved pain and distress can have implications across the lifespan.  This is an update of a previously published review in the Cochrane Database of Systematic Reviews, Issue 10 2011 entitled 'Non-pharmacological management of infant and young child procedural pain'.

OBJECTIVES

To assess the efficacy of non-pharmacological interventions for infant and child (up to three years) acute pain, excluding kangaroo care, and music. Analyses were run separately for infant age (preterm, neonate, older) and pain response (pain reactivity, immediate pain regulation). 

SEARCH METHODS

For this update, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (Issue 2 of 12, 2015), MEDLINE-Ovid platform (March 2015), EMBASE-OVID platform (April 2011 to March 2015), PsycINFO-OVID platform (April 2011 to February 2015), and CINAHL-EBSCO platform (April 2011 to March 2015). We also searched reference lists and contacted researchers via electronic list-serves. New studies were incorporated into the review. We refined search strategies with a Cochrane-affiliated librarian. For this update, nine articles from the original 2011 review pertaining to Kangaroo Care were excluded, but 21 additional studies were added.

SELECTION CRITERIA

Participants included infants from birth to three years. Only randomised controlled trials (RCTs) or RCT cross-overs that had a no-treatment control comparison were eligible for inclusion in the analyses. However, when the additive effects of a non-pharmacological intervention could be assessed, these studies were also included. We examined studies that met all inclusion criteria except for study design (e.g. had an active control) to qualitatively contextualize results. There were 63 included articles in the current update.

DATA COLLECTION AND ANALYSIS

Study quality ratings and risk of bias were based on the Cochrane Risk of Bias Tool and GRADE approach. We analysed the standardized mean difference (SMD) using the generic inverse variance method.

MAIN RESULTS

Sixty-three studies, with 4905 participants, were analysed. The most commonly studied acute procedures were heel-sticks (32 studies) and needles (17 studies). The largest SMD for treatment improvement over control conditions on pain reactivity were: non-nutritive sucking-related interventions (neonate: SMD -1.20, 95% CI -2.01 to -0.38) and swaddling/facilitated tucking (preterm: SMD -0.89; 95% CI -1.37 to -0.40). For immediate pain regulation, the largest SMDs were: non-nutritive sucking-related interventions (preterm: SMD -0.43; 95% CI -0.63 to -0.23; neonate: SMD -0.90; 95% CI -1.54 to -0.25; older infant: SMD -1.34; 95% CI -2.14 to -0.54), swaddling/facilitated tucking (preterm: SMD -0.71; 95% CI -1.00 to -0.43), and rocking/holding (neonate: SMD -0.75; 95% CI -1.20 to -0.30). Fifty two of our 63 trials did not report adverse events. The presence of significant heterogeneity limited our confidence in the findings for certain analyses, as did the preponderance of very low quality evidence.

AUTHORS' CONCLUSIONS

There is evidence that different non-pharmacological interventions can be used with preterms, neonates, and older infants to significantly manage pain behaviors associated with acutely painful procedures. The most established evidence was for non-nutritive sucking, swaddling/facilitated tucking, and rocking/holding. All analyses reflected that more research is needed to bolster our confidence in the direction of the findings. There are significant gaps in the existing literature on non-pharmacological management of acute pain in infancy.

Pain sensitivity of children with Down syndrome and their siblings: quantitative sensory testing versus parental reports

AIM

The aim of this study was to compare thermal detection and pain thresholds in children with Down syndrome with those of their siblings.

METHOD

Sensory detection and pain thresholds were assessed in children with Down syndrome and their siblings using quantitative testing methods. Parental questionnaires addressing developmental age, pain coping, pain behaviour, and chronic pain were also utilized.

RESULTS

Forty-two children with Down syndrome (mean age 12y 10mo) and 24 siblings (mean age 15y) participated in this observational study. The different sensory tests proved feasible in 13 to 29 (33-88%) of the children with Down syndrome. These children were less sensitive to cold and warmth than their siblings, but only when measured with a reaction time-dependent method, and not with a reaction time-independent method. Children with Down syndrome were more sensitive to heat pain, and only 6 (14%) of them were able to adequately self-report pain, compared with 22 (92%) of siblings (p<0.001).

INTERPRETATION

Children with Down syndrome will remain dependent on pain assessment by proxy, since self-reporting is not adequate. Parents believe that their children with Down syndrome are less sensitive to pain than their siblings, but this was not confirmed by quantitative sensory testing.

A Randomized Controlled Trial of the Use of Oral Glucose with or without Gentle Facilitated Tucking of Infants during Neonatal Echocardiography

Objective

To compare the effect of oral glucose given with or without facilitated tucking (FT), versus placebo (water) to facilitate image acquisition during a targeted neonatal echocardiography (TNE).

Design

Factorial, double blind, randomized controlled trial.

Setting

Tertiary neonatal intensive care unit (NICU).

Patients

Infants born between 26 and 42 weeks of gestation (GA).

Interventions

One of four treatment groups: oral water (placebo), oral glucose (25%), facilitated tucking with oral water or facilitated tucking with oral glucose, during a single, structured TNE. All infants received a soother.

Main Outcome Measure

Change in Behavioral Indicators of Infant Pain (BIIP) scores.

Results

104 preterm infants were randomized (mean ± SD GA: 33.4 ± 3.5 weeks). BIIP scores remained low during the echocardiography scan (median, [IQ range]: 0, [0 to 1]). There were no differences in the level of agitation of infants amongst the treatment groups, with estimated reductions in mean BIIP relative to control of 0.27 (95%CI -0.40 to 0.94) with use of oral glucose and .04 (-0.63 to 0.70) with facilitated tucking. There were also no differences between treatment groups in the quality and duration of the echocardiography scans.

Conclusions

In stable infants in the NICU, a TNE can be performed with minimal disruption in a majority of cases, simply by providing a soother. The use of 25% glucose water in this context did not provide further benefit in reducing agitation and improving image acquisition.

Clinical Trial Registration

Clinical Trials.gov: NCT01253889

Preterm infants' behaviors and skin conductance responses to nurse handling in the NICU

Stress response patterns are indicative of the neonate's unique ability to cope with environmental demands and can be evaluated through autonomic and behavioral response parameters.

OBJECTIVE

To characterize stress responses during tactile stimulation to standard nurse handling in the NICU, and their association with severity of illness in preterm infants.

METHODS

Thirty preterm neonates were studied at postnatal day 4-5 during standard nurse caregiving. Heart rate (HR), respiratory rate (RR), skin conductance responses per second (SCR/s), and NIDCAP® stress behaviors were recorded before and during care. Non-parametric tests were used to assess differences from before to during care. Pearson's correlations were used to determine the association of biological and behavioral variables to the score for neonatal acute physiology (SNAP), a severity of illness index.

RESULTS

HR, RR, SCR/s and NIDCAP® behaviors (motor and attentional cues, and ability to self-console) increased from before to during the care (p < 0.01). NIDCAP® behaviors showed a significant negative association to the SNAP score (R = -0.45, p < 0.05).

CONCLUSIONS

HR, RR, SCR/s and NIDCAP® behaviors significantly increased during care. NIDCAP® stress behaviors were influenced by the severity of illness of the infant, while SCR/s was not influenced by severity of illness.

HELPinKids&Adults Knowledge Synthesis of the Management of Vaccination Pain and High Levels of Needle Fear: Limitations of the Evidence and Recommendations for Future Research

The HELPinKids&Adults knowledge synthesis for the management of vaccination-related pain and high levels of needle fear updated and expanded upon the 2010 HELPinKIDS knowledge synthesis and clinical practice guideline for pain mitigation during vaccine injections in childhood. Interventions for vaccine pain management in adults and treatment of individuals with high levels of needle fear, phobias, or both were included, thereby broadening the reach of this work. The present paper outlines the overarching limitations of this diverse evidence base and provides recommendations for future research. Consistent with the framing of clinical questions in the systematic reviews, the Participants, Intervention, Comparison, Outcome, Study design (PICOAS) framework was used to organize these predominant issues and research directions. The major limitations we identified across systematic reviews were an overall dearth of trials on vaccination, lack of methodological rigor, failure to incorporate important outcomes, poor study reporting, and various sources of heterogeneity. Future research directions in terms of conducting additional trials in the vaccination context, improving methodological quality and rigor, assessment of global acceptability and feasibility of interventions, and inclusion of outcomes that stakeholders consider to be important (eg, compliance) are recommended. Given concerns about pain and fear are known contributors to vaccine hesitancy, improving and expanding this evidence base will be integral to broader efforts to improve vaccine compliance and public health worldwide.

Comforting strategies and perceived barriers to pediatric pain management during IV line insertion procedure in Uganda's national referral hospital: A descriptive study

BACKGROUND

Venipuncture and intravenous (IV) cannula insertions are the two common sources of pain in hospitalized children and health care today. The WHO asserts that, pain relief is a basic fundamental right and requires a multidisciplinary approach. Nonpharmacological comforting strategies when implemented are important to relive pain related distress in children during peripheral IV line insertion. However, evidence to date that suggests implementation of such strategies and their barriers in Uganda remains very limited. This study aimed at establishing the current practices in regard to the use of comforting strategies and the perceived barriers faced by health care providers to implement pediatric pain management during IV line insertion procedure in Uganda's national referral hospital, Mulago.

METHOD

A cross sectional and descriptive study was conducted between December 1, 2012 and February 28, 2013 involving doctors, nurses and interns in six pediatric wards of Mulago Hospital in Uganda. A pre-tested self- administered and semi- structured questionnaire was used to collect the data. Data was entered into SPSS and descriptive statistics run on all the variables.

RESULTS

Of the 120 questionnaires distributed, 105 (RR = 87.5%) were returned and completed. The evidence based comforting strategies used for pain management during IV line insertion by the majority of health care professionals were; skin to skin (51%) and appropriate upright positioning of the child on mother's lap (69%). The least used comforting strategies were; allowing the child to suck his thumb or hand (70%), use of distraction (69%) and directing the child to suck one of his fingers into his mouth (90%). The identified barriers to implementing comforting strategies were; lack of time (42%), having emergency situations (18%), and not knowing the right method to use (11%). Of 105, 100 (95%) reported that there is need for continuous professional development on comforting strategies.

CONCLUSIONS

Findings demonstrated that fewer health care providers used some evidence based comforting strategies of pain relief during pediatric peripheral IV line insertion. Distraction and other evidence based strategies for pain and distress relieve are less often used by the majority of the health care providers. Incorporating pediatric pain management content in all health professionals training curricula could improve the current practices for better health outcomes.

The relationship between nociceptive brain activity, spinal reflex withdrawal and behaviour in newborn infants

Measuring infant pain is complicated by their inability to describe the experience. While nociceptive brain activity, reflex withdrawal and facial grimacing have been characterised, the relationship between these activity patterns has not been examined. As cortical and spinally mediated activity is developmentally regulated, it cannot be assumed that they are predictive of one another in the immature nervous system. Here, using a new experimental paradigm, we characterise the nociceptive-specific brain activity, spinal reflex withdrawal and behavioural activity following graded intensity noxious stimulation and clinical heel lancing in 30 term infants. We show that nociceptive-specific brain activity and nociceptive reflex withdrawal are graded with stimulus intensity (p < 0.001), significantly correlated (r = 0.53, p = 0.001) and elicited at an intensity that does not evoke changes in clinical pain scores (p = 0.55). The strong correlation between reflex withdrawal and nociceptive brain activity suggests that movement of the limb away from a noxious stimulus is a sensitive indication of nociceptive brain activity in term infants. This could underpin the development of new clinical pain assessment measures.

Persistent changes in peripheral and spinal nociceptive processing after early tissue injury

It has become clear that tissue damage during a critical period of early life can result in long-term changes in pain sensitivity, but the underlying mechanisms remain to be fully elucidated. Here we review the clinical and preclinical evidence for persistent alterations in nociceptive processing following neonatal tissue injury, which collectively point to the existence of both a widespread hypoalgesia at baseline as well as an exacerbated degree of hyperalgesia following a subsequent insult to the same somatotopic region. We also highlight recent work investigating the effects of early trauma on the organization and function of ascending pain pathways at a cellular and molecular level. These effects of neonatal injury include altered ion channel expression in both primary afferent and spinal cord neurons, shifts in the balance between synaptic excitation and inhibition within the superficial dorsal horn (SDH) network, and a 'priming' of microglial responses in the adult SDH. A better understanding of how early tissue damage influences the maturation of nociceptive circuits could yield new insight into strategies to minimize the long-term consequences of essential, but invasive, medical procedures on the developing somatosensory system.

Perceptions of health professionals on pain in extremely low gestational age infants

Extremely low gestational age infants (<28 weeks at birth) experience significant pain from repeated therapeutic procedures while hospitalized in the neonatal intensive care unit. As part of a program of research examining pain in preterm infants, we conducted a qualitatively driven mixed-methods design, supplemented with a qualitative and quantitative component, to understand how health care professionals (HCPs) assess and manage procedural pain for tiny and underdeveloped preterm infants. Fifty-nine HCPs from different disciplines across four tertiary-level neonatal units in Canada participated in individual or focus group interviews and completed a brief questionnaire. Four themes from the content analysis were (a) subtlety and unpredictability of pain indicators, (b) infant and caregiver attributes and contextual factors that influence pain response and practices, (c) the complex nature of pain assessment, and (d) uncertainty in the management of pain. The information gleaned from this study can assist in identifying gaps in knowledge and informing unit-based and organizational knowledge translation strategies for this vulnerable population.

fMRI reveals neural activity overlap between adult and infant pain

Limited understanding of infant pain has led to its lack of recognition in clinical practice. While the network of brain regions that encode the affective and sensory aspects of adult pain are well described, the brain structures involved in infant nociceptive processing are less well known, meaning little can be inferred about the nature of the infant pain experience. Using fMRI we identified the network of brain regions that are active following acute noxious stimulation in newborn infants, and compared the activity to that observed in adults. Significant infant brain activity was observed in 18 of the 20 active adult brain regions but not in the infant amygdala or orbitofrontal cortex. Brain regions that encode sensory and affective components of pain are active in infants, suggesting that the infant pain experience closely resembles that seen in adults. This highlights the importance of developing effective pain management strategies in this vulnerable population.

DOI:http://dx.doi.org/10.7554/eLife.06356.001

Doctors long believed that infants do not feel pain the way that older children and adults do. Instead, they believed that the infants' responses to discomfort were reflexes. Based on these beliefs, it was a routine practice to perform surgery on infants without suitable pain relief up until the late 1980s. Even now, infants may receive less than ideal pain relief. For example, a review found that although newborns in intensive care units undergo 11 painful procedures per day on average, more than half of the babies received no pain medications. Some guidelines continue to emphasize that for infants cuddling and feeding are more important sources of comfort than pain-relieving drugs.

There is growing support for better pain control for infants. Doctors and nurses now routinely observe behaviour and physiological responses—such as heart rate—to assess whether infants are experiencing pain. When an infant shows signs of pain, medical staff may give the infant sugar water or other interventions aimed at reducing their distress. However, recordings of brain activity suggest that infants may experience pain without exhibiting physical signs and that sugar water may reduce the behaviours associated with pain but not the pain itself.

More objective measurements of infant pain would be useful, but to create such measurements scientists must first understand how infants experience pain. So Goksan et al. used a technique called functional magnetic resonance imaging (fMRI) to compare the brain responses of adults and newborns to the same stimulus—a sharp poke of the foot. The adults were also asked about the pain they experienced, and whether the infants pulled their foot away when poked was documented.

The fMRI results revealed that pain increased activity in 20 regions in the adults' brains, and 18 of the same regions in the infants' brains. The brain regions activated in the infants' brains in response to a poke on the foot are involved in processing sensations and emotions. The two regions that did not activate in the infant brains—the amygdala and the orbitofrontal cortex—help individuals interpret the stimuli. Goksan et al. therefore conclude that infants experience pain in similar ways to adults, though they may not experience all the emotions that adults have when they are in pain. It is, therefore, important to give infants suitable pain relief during potentially painful procedures.

DOI:http://dx.doi.org/10.7554/eLife.06356.002

[Non-pharmaceutical measures, topical analgesics and oral administration of glucose in pain management: Austrian interdisciplinary recommendations on pediatric perioperative pain management]

Non-pharmaceutical procedures are increasingly being used in pediatric pain therapy in addition to pharmaceutical procedures and have a supporting function. This article describes the non-pharmaceutical procedures which have an influence on perioperative and posttraumatic pain in children and adolescents. Prerequisites for every adequate pain therapy are affection, imparting a feeling of security, distraction and the creation of a child-oriented environment. Topical analgesics are indicated for application to intact skin for surface anesthesia. For a safe use consideration must be given to the duration of application, the dose and the maximum area of skin treated in an age-dependent manner. For simple but painful procedures in premature infants, neonates and infants, pain can be effectively reduced by the oral administration of glucose. The positive effect is guaranteed particularly for the use in a once only pain stimulation. Non-nutritive sucking, swaddling, facilitated tucking and kangaroo mother care, for example can be used as supportive measures during slightly painful procedures. There is insufficient evidence for a pain reducing effect in older infants and small children. Physical therapeutic procedures can be used as accompanying measures for acute pain and are individually adapted. However, the limited amount of currently available data is insufficient to make a critical scientific assessment of the individual measures. The effects can, however, be observed in the daily routine practice. Psychological methods can facilitate coping with pain. In situations with mental and psychiatric comorbidities or psychosocial impairment, a psychologist should be consulted. Acupuncture and hypnosis are also a meaningful addition within the framework of multimodal pain therapy.

Assessment of pain during application of nasal-continuous positive airway pressure and heated, humidified high-flow nasal cannulae in preterm infants

OBJECTIVE

To assess pain and compare its severity in preterm infants during application of nasal-continuous positive airway pressure (nCPAP) and heated, humidified high-flow nasal cannulae (HHHFNC).

STUDY DESIGN

An observational cross-sectional study. Sixty preterm infants, categorized into nCPAP (n=37) and HHHFNC groups (n=23). Pain response was assessed using Premature Infant Pain Profile (PIPP), duration of first cry and salivary-cortisol concentrations.

RESULT

The PIPP scores were significantly higher in the nCPAP compared with HHHFNC group (10 (7-12) vs 4 (2-6), P<0.01). None of the infants in the HHHFNC group had severe pain defined as a PIPP score >12, compared with 5 (13.5%) infants in the nCPAP group. Salivary-cortisol concentrations were significantly higher in nCPAP group compared with the HHHFNC group (5.0 (3.6-5.9) vs 1.6 (1.0-2.3) nmol l(-1), P<0.01). A lower incidence of cry was observed for infants in the HHHFNC group compared with the nCPAP group (11 (47.8%) vs 30 (81.1%), P<0.001), however, the duration of first cry was not significantly different between groups. The respiratory rate was significantly lower after application of HHHFNC compared with nCPAP (P<0.001). There were no significant differences between groups with regard to fraction of inspired oxygen (FiO2), oxygen saturation by pulse oximeter (SpO2) and heart rate.

CONCLUSION

The application of HHHFNC in preterm infants is associated with less pain compared with nCPAP, as it is associated with less PIPP scores and lower salivary-cortisol concentrations.

Sucrose and warmth for analgesia in healthy newborns: an RCT

BACKGROUND AND OBJECTIVE

Increasing data suggest that neonatal pain has long-term consequences. Nonpharmacologic techniques (sucrose taste, pacifier suckling, breastfeeding) are effective and now widely used to combat minor neonatal pain. This study examined the analgesic effect of sucrose combined with radiant warmth compared with the taste of sucrose alone during a painful procedure in healthy full-term newborns.

METHODS

A randomized, controlled trial included 29 healthy, full-term newborns born at the University of Chicago Hospital. Both groups of infants were given 1.0 mL of 25% sucrose solution 2 minutes before the vaccination, and 1 group additionally was given radiant warmth from an infant warmer before the vaccination. We assessed pain by comparing differences in cry, grimace, heart rate variability (ie, respiratory sinus arrhythmia), and heart rate between the groups.

RESULTS

The sucrose plus warmer group cried and grimaced for 50% less time after the vaccination than the sucrose alone group (P < .05, respectively). The sucrose plus warmer group had lower heart rate and heart rate variability (ie, respiratory sinus arrhythmia) responses compared with the sucrose alone group (P < .01), reflecting a greater ability to physiologically regulate in response to the painful vaccination.

CONCLUSIONS

The combination of sucrose and radiant warmth is an effective analgesic in newborns and reduces pain better than sucrose alone. The ready availability of this practical nonpharmacologic technique has the potential to reduce the burden of newborn pain.

Cortical activity evoked by inoculation needle prick in infants up to one-year old

Inoculation is one of the first and most common experiences of procedural pain in infancy. However, little is known about how needle puncture pain is processed by the central nervous system in children. In this study, we describe for the first time the event-related activity in the infant brain during routine inoculation using electroencephalography. Fifteen healthy term-born infants aged 1 to 2 months (n = 12) or 12 months (n = 5) were studied in an outpatient clinic. Pain behavior was scored using the Modified Behavioral Pain Scale. A distinct inoculation event-related vertex potential, consisting of 2 late negative-positive complexes, was observable in single trials after needle contact with the skin. The amplitude of both negative-positive components was significantly greater in the 12-month group. Both inoculation event-related potential amplitude and behavioral pain scores increased with age but the 2 measures were not correlated with each other. These components are the first recordings of brain activity in response to real-life needle pain in infants up to a year old. They provide new evidence of postnatal nociceptive processing and, combined with more traditional behavioral pain scores, offer a potentially more sensitive measure for testing the efficacy of analgesic protocols in this age group.

Topical anesthesia or oral dextrose for the relief of pain in screening for retinopathy of prematurity: a randomized controlled double-blinded trial

OBJECTIVE

Compare efficacy of 0.5% proparacaine eye drops and oral 25% dextrose in reducing pain during screening for retinopathy of prematurity (ROP).

PATIENTS AND METHODS

Double-blinded randomized controlled trial. Twenty eligible babies were randomized. Group I received 0.5% proparacaine eye drops at first ROP screening, while Group II received 25% dextrose orally. At second examination, babies received no intervention. Pain was assessed using Premature Infant Pain Profile (PIPP) score.

RESULTS

The mean ( ± SD) PIPP during procedure in Group I were 15.5 ± 2.06 and 14 ± 2.4 at first and second screening (p = 0.259). The mean ( ± SD) PIPP in Group II were 14.2 ± 1. 8 and 14.9 ± 2.5 at the first and second screening (p = 0.428). Differences were not statistically significant. The PIPP scores of Group I and Group II at the first screening were also not significantly different (p = 0.165).

CONCLUSION

ROP screening causes moderate to severe pain and neither proparacaine nor dextrose is an effective analgesic.

Early repetitive pain in preterm infants in relation to the developing brain

Infants born preterm (<37 weeks of gestation) are particularly vulnerable to procedural stress and pain exposure during neonatal intensive care, at a time of rapid and complex brain development. Concerns regarding effects of neonatal pain on brain development have long been expressed. However, empirical evidence of adverse associations is relatively recent. Thus, many questions remain to be answered. This review discusses the short- and long-term effects of pain-related stress and associated treatments on brain maturation and neurodevelopmental outcomes in children born preterm. The current state of the evidence is presented and future research directions are proposed.

Pain in the neonate: focus on nonpharmacologic interventions

The assessment and treatment of pain in the neonate, especially preterm neonates, has been a challenge in the NICU for many years. Nurses caring for these vulnerable patients are in a key position to not only recognize when the neonate is experiencing pain but to also work collaboratively with other health care providers in determining the best method to treat and help prevent pain associated with procedures and routine caregiving activities. The American Academy of Pediatrics along with parent groups has recognized the importance of pain-prevention programs in treating pain in the neonate. Nurses, by anticipating and reducing both painful procedures and bedside interruptions, along with innovative nonpharmacologic interventions, can dramatically decrease the neonate's exposure to pain and the potential for long-term effects. An overview of nonpharmacologic interventions in the treatment of neonatal pain is provided for NICU nurses to help them effectively reduce their patient's pain and discomfort.

Noxious stimulation in children receiving general anaesthesia evokes an increase in delta frequency brain activity

More than 235,000 children/year in the UK receive general anaesthesia, but it is unknown whether nociceptive stimuli alter cortical brain activity in anaesthetised children. Time-locked electroencephalogram (EEG) responses to experimental tactile stimuli, experimental noxious stimuli, and clinically required cannulation were examined in 51 children (ages 1–12 years) under sevoflurane monoanaesthesia. Based on a pilot study (n = 12), we hypothesised that noxious stimulation in children receiving sevoflurane monoanaesthesia would evoke an increase in delta activity. This was tested in an independent sample of children (n = 39), where a subset (n = 11) had topical local anaesthetic applied prior to stimulation. A novel method of time-locking the stimuli to the EEG recording was developed using an event detection interface and high-speed camera. Clinical cannulation evoked a significant increase (34.2 ± 8.3%) in delta activity (P = 0.042), without concomitant changes in heart rate or reflex withdrawal, which was not observed when local anaesthetic was applied (P = 0.30). Experimental tactile (P = 0.012) and noxious (P = 0.0099) stimulation also evoked significant increases in delta activity, but the magnitude of the response was graded with stimulus intensity, with the greatest increase evoked by cannulation. We demonstrate that experimental and clinically essential noxious procedures, undertaken in anaesthetised children, alter the pattern of EEG activity, that this response can be inhibited by local anaesthetic, and that this measure is more sensitive than other physiological indicators of nociception. This technique provides the possibility that sensitivity to noxious stimuli during anaesthesia could be investigated in other clinical populations.

Cerebral hemodynamic changes and pain perception during venipuncture: is glucose really effective?

Newborns are exposed to a considerable number of painful stimuli. This study is aimed to investigate the effects of 30% glucose solution and nonnutritive sucking on pain perception during venipuncture. Twenty-five term infants were randomized as receiving 30% dextrose (group 1) or sterile water (group 2). Neonatal Infant Pain Scale scores, skin conductance algesimeter recordings, and near-infrared spectroscopy measurements were recorded during the procedure. Neonatal Infant Pain Scale and skin conductance algesimeter results were decreased in both groups from that during venipuncture to after the procedure. Group 1 had lower Neonatal Infant Pain Scale scores compared with group 2 after venipuncture, different from the skin conductance algesimeter, where no difference was observed between groups. In group 1, cerebral blood volume increased after venipuncture. Glucose does not attenuate the Neonatal Infant Pain Scale score and skin conductance algesimeter index during venipuncture, but it leads to a lower Neonatal Infant Pain Scale score after venipuncture unlike the skin conductance algesimeter index, which was not lowered.

Impact of repeated procedural pain-related stress in infants born very preterm

The majority of infants born very preterm (24-32 wk gestational age) now survive; however, long-term neurodevelopmental and behavioral problems remain a concern. As part of their neonatal care, very preterm infants undergo repeated painful procedures during a period of rapid brain development and programming of stress systems. Infants born this early have the nociceptive circuitry required to perceive pain, however, their sensory systems are functionally immature. An imbalance of excitatory vs. inhibitory processes leads to increased nociceptive signaling in the central nervous system. Specific cell populations in the central nervous system of preterm neonates are particularly vulnerable to excitoxicity, oxidative stress, and inflammation. Neonatal rat models have demonstrated that persistent or repeated pain increases apoptosis of neurons, and neonatal pain and stress lead to anxiety-like behaviors during adulthood. In humans, greater exposure to neonatal pain-related stress has been associated with altered brain microstructure and stress hormone levels, as well as with poorer cognitive, motor, and behavioral neurodevelopment in infants and children born very preterm. Therefore, it is important that pain-related stress in preterm neonates is accurately identified, appropriately managed, and that pain management strategies are evaluated for protective or adverse effects in the long term.

Neonatal pain control and neurologic effects of anesthetics and sedatives in preterm infants

Preclinical and clinical studies have demonstrated the adverse consequences of untreated pain and stress on brain development in the preterm infant. Sucrose has widely been implemented as standard therapy for minor procedural pain. Anesthetics are commonly utilized in preterm infants during major surgery. Pharmacologic agents (benzodiazepines and opioids) have been examined in clinical trials of preterm infants requiring invasive mechanical ventilation. Controversy exists regarding the safety and long-term impact of these interventions. Ongoing multidisciplinary research will help define the impact of these agents and identify potential alternative therapies.

Neurophysiological measures of nociceptive brain activity in the newborn infant--the next steps

Infants within neonatal intensive care units can receive multiple medically essential painful procedures per day. How they respond to these events, how best to alleviate the negative effects, and the long-term consequences for the infant are all significant questions that have yet to be fully answered. In recent years, several studies have examined cortical responses to noxious stimuli in the neonate through the use of near-infrared spectroscopy (NIRS) and electroencephalography (EEG). These investigations dispel any notion that the newborn infant does not process noxious stimuli at a cortical level and open the way for future research. In this Viewpoint Article, we review these studies and discuss key clinical challenges which may be elucidated with the use of these techniques.

Conclusion

Simultaneously measuring the changes that are evoked in behaviour, physiology and the cortex following noxious events will provide the best approach to understanding the neonate's experience of pain.

Evoked potentials in the Atlantic cod following putatively innocuous and putatively noxious electrical stimulation: a minimally invasive approach

Aspects of peripheral and central nociception have previously been studied through recording of somatosensory evoked potentials (SEPs) to putative noxious stimuli in specific brain regions in a few freshwater fish species. In the present study, we describe a novel, minimally invasive method for recording SEPs from the central nervous system of the Atlantic cod (Gadus morhua). Cutaneous electric stimulation of the tail in 15 fish elicited SEPs at all stimulus intensities (2, 5, 10 and 20 mA) with quantitative properties corresponding to stimulus intensity. In contrast to previous fish studies, the methodological approach used in Atlantic cod in the current study uncovered a number of additional responses that could originate from multiple brain regions. Several of these responses were specific to stimulation at the highest stimulus intensities, possibly representing qualitative differences in central processing between somatosensory and nociceptive stimuli.