Can adverse neonatal experiences alter brain development and subsequent behavior?

[Pain indicators in newborns]

DEFINITION OF PAIN: The International Association for the Study of Pain has defined pain as "an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage." The interpretation of pain is subjective. Each person forms an internal construct of pain through encountered injury. PAIN AND NEWBORN: The issue of pain perception in newborns, its management and prevention has been neglected for decades. The inability of "self-report" of painful experience has contributed significantly to misunderstanding of the importance of this problem and inadequate treatment. The main characteristic of this 'critical window of brain development' period is rapid enlargement of brain volume and its great plasticity. Harmful short-term and long-term consequences can arise as a consequence of disturbance of the sophisticated balance between newborn and its surrounding. NEONATAL PAIN INDICATORS: As a response to a present painful stimulus, the newborn adapts to this acute stress with changes in endocrine, vegetative, immune and behavioral area. An ideal pain indicator in neonatal period does not exist. There are several different groups of them, namely contextual and developmental indicators (gestational age, contributed illness, medication, for example), physiological (heart rate, vagal tone, breathing rate, blood pressure, oxygen saturation, transcutaneous partial pressures of oxygen and carbon-dioxide, intracranial pressure, palm sweating) and behavioral ones (face expression, movements of limbs, cry), several neonatal pain scales were constructed on the basis of these indicators.

A neurobiological model for the effects of early brainstem functioning on the development of behavior and emotion regulation in infants: implications for prenatal and perinatal risk

Neurobiological models propose an evolutionary, vertical-integrative perspective on emotion and behavior regulation, which postulates that regulatory functions are processed along three core brain systems: the brainstem, limbic, and cortical systems. To date, few developmental studies applied these models to research on prenatal and perinatal risk. We propose a conceptual model that incorporates three integrated levels of observations for the study of early risk: (a) brainstem-related physiological regulation of cyclic processes and sensory integration, e.g., vagal regulation, circadian rhythms; (b) emotion and attention regulation capacities that draw on the integration of brainstem and limbic systems; and (c) higher-level outcomes that draw on the intactness of brainstem and limbic networks, including socio-emotional self-regulation, inhibitory control, and cognitive processing. We discuss implications of the model for the development of regulatory capacities during the prenatal and early postnatal stages in infants born with specific perinatal risk. We underscore the importance of assessing sub-cortical and brainstem systems and the longitudinal effects of transitory brainstem dysfunction on physiological homeostasis, motivation, arousal-modulated attention, stress reactivity, and mother-infant co-regulation. The assessment of brainstem dysfunction can be conducted during hospitalization and may help detect infants at risk for the development of self-regulatory deficits at the first weeks of life.

Naturally occurring variations in maternal care modulate the effects of repeated neonatal pain on behavioral sensitivity to thermal pain in the adult offspring

Repeated pain during a critical period of development can have long-term behavioral and physiological consequences in both human and animals. We previously showed that rat mothers caring for pups subjected to mild pain in neonatal life increased pup licking and grooming behavior. Therefore, we tested whether naturally occurring variations in maternal behavior would modulate the effects of repeated mild inflammatory pain on behavioral responses to pain and stress in the adult male offspring. Rat pups were either uninjected (UI) or injected twice daily between PND3 and PND14 with either saline (0.9%) or formalin (0.2-0.4%) in the footpad of the hindpaw. Maternal behavior (pup licking and grooming) was recorded under basal conditions and after reunion with the litter post injection to determine maternal phenotype (High, Middle, Low licking). Adult offspring (PND60) were tested for their thermal sensitivity, inflammatory pain responses after formalin injection and neuroendocrine responses to formalin injection. Maternal phenotype significantly altered pain sensitivity after thermal stimulation, but not formalin injection. Offspring from the High licking mothers displayed increased withdrawal latencies compared to offspring from Low mothers, regardless of neonatal treatment. Pain responses after formalin injection were higher in offspring receiving formalin as neonates compared to saline-treated or uninjected rats, demonstrating a long lasting increased sensitivity to inflammatory pain. Neuroendocrine responses to pain stress were not affected by neonatal treatment. These data suggest that changes in maternal behavior can influence some modalities of pain sensitivity and that repeated mild inflammatory pain in neonatal period causes hypersensitivity to formalin in the adult offspring.

Remifentanil for percutaneous intravenous central catheter placement in preterm infant: a randomized controlled trial

BACKGROUND

There is limited evidence on the analgesic efficacy of opioids during percutaneous intravenous central catheter (PICC) insertion in preterm infants.

AIM

To assess the analgesic and procedural efficacy of low-dose remifentanil infusion during PICC in preterm infants.

METHODS

Fifty-four neonates [mean gestational age (+/-sd) 28 +/- 2 weeks; birth weight 1126 +/- 337 g] were randomly assigned to remifentanil infusion at 0.03 mcg.kg(-1).min(-1) (R) or placebo (C) in addition to 0.3 ml of 12% sucrose per os and non-nutritive sucking.

RESULTS

Validated pain scales [Neonatal Infants Pain Scale (NIPS) and Premature Infants Pain Profile (PIPP)] administered at the baseline T0, skin preparation T1, needle insertion T2, and recovery T3, revealed differences in mean NIPS scores (C 5.3 +/- 1.3 vs R 4.2 +/- 1.4 at T1 and C 5.0 +/- 1.3 vs R 3.4 +/- 1.3 at T2) and PIPP scores (C 9.3 +/- 1.6 vs R 7.1 +/- 1.5 at T1 and C 8.6 +/- 1.7 vs R 6.1 +/- 1.4 at T2); P < 0.05. Cardiovascular and respiratory response, and body movements during PICC suggested better pain and distress control with remifentanil (P < 0.05), but the time to complete the maneuver and the number of attempts needed remained the same in the two groups.

CONCLUSIONS

Low-dose remifentanil has a measurable, synergic analgesic effect in combination with 12% sucrose and non-nutritive sucking, but does not make PICC easier or quicker.

Anaesthesia and analgesia: contribution to surgery, present and future

Anaesthetists provide comprehensive perioperative medical care to patients undergoing surgical and diagnostic procedures, including postoperative intensive care when needed. They are involved in the management of perioperative acute pain as well as chronic pain. This manuscript considers some of the recent advances in modern anaesthesia and their contribution to surgery, from the basic mechanisms of action, to the delivery systems for general and regional anaesthesia, to the use of new drugs and new methods of monitoring. It assesses the resulting progress in acute and chronic pain services and looks at patient safety and risk management. It speculates on directions that may shape its future contributions to the management of the patient undergoing surgery.

Pain behaviours in Extremely Low Gestational Age infants

BACKGROUND

To date, there are over 40 infant pain measures. Despite this plethora of measures, only 8 have included preterm infants and only 2 have included Extremely Low Gestational Age (ELGA; infants <28 weeks GA) in their development. Without reliable, valid and clinically useful indicators for procedural pain in ELGA infants, clinicians have no means to interpret the responses from an immature infant who may respond differently from infants of older GA.

OBJECTIVE

To examine the physiological, behavioural and biochemical responses to painful and non-painful procedures in ELGA infants and the influence of GA and sex.

DESIGN/METHODS

A prospective crossover design with 50 ELGA infants from one Canadian tertiary level NICU was conducted. Infants were assessed in random order during standardized painful (heel lance) and non-painful (diaper change) procedures. Physiological (heart rate, oxygen saturation) and behavioural (facial and body movement) indicators were continuously collected during 4 phases of the procedures. Biochemical (salivary cortisol) indicators were collected immediately before and 20 min following the procedures.

RESULTS

Four facial actions (brow bulge, eye squeeze, nasolabial furrow, vertical mouth stretch) increased immediately following the heel lance. There were no specific changes in physiological, body movement or cortisol indicators following the heel lance. ELGA infants demonstrated greater body movements during the diaper change, which may reflect immature motor coordination. No differences in pain responses were found for infants born between 23-25 6/7 weeks GA and those between 26-28 weeks GA. Similarly, no gender differences were found.

CONCLUSIONS

Changes in 4 facial actions were the most sensitive indicators of pain in ELGA infants. This finding is consistent with existing measures where facial actions are the most prominent pain indicators. Specific body movements such as those included in NIDCAP, may provide more information about pain in ELGA infants. Movements such as hand-on-face, finger splaying, fisting, arching or yawning need to be examined in future research.

The impact of postnatal environment on opioid peptides in young and adult male Wistar rats

Early environmental influences can change the neuronal development and thereby affect behavior in adult life. The aim in the present study was to thoroughly examine the impact of early environmental factors on endogenous opioids by using a rodent maternal separation (MS) model. The endogenous opioid peptide system is not fully developed at birth, and short- and/or long-term alterations may occur in these neural networks in animals exposed to manipulation of the postnatal environment. Rat pups were subjected to one of five rearing conditions; 15 min (MS15) litter (l) or individual (i), 360 min (MS360) l or i daily MS, or housed under normal animal facility rearing (AFR) conditions during postnatal days 1-21. Measurements of immunoreactive (ir) Met-enkephalin-Arg6Phe7 (MEAP) and dynorphin B (DYNB) peptide levels in the pituitary gland and in a number of brain areas, were performed at three and 10 weeks of age, respectively. MS-induced changes were more pronounced in ir MEAP levels, especially in individually separated rats at three weeks of age and in litter-separated rats at 10 weeks of age. The enkephalin and dynorphin systems have different developmental patterns, dynorphin appearing earlier, which may point at a more sensitive enkephalin system during the early postnatal weeks. The results provide evidence that opioid peptides are sensitive for early environmental factors and show that the separation conditions are critical and also result in changes manifesting at different time points. MS-induced effects were observed in areas related to stress, drug reward and dependence mechanisms. By describing effects on opioid peptides, the study addresses the possible role of a deranged endogenous opioid system in the previously described behavioral consequences of MS.

Long-term deficits of preterm birth: evidence for arousal and attentional disturbances

OBJECTIVE

Quantitative measures of pre-attentional, attentional and frontal lobe processes were compared to evaluate quantitative measures of these deficits in Ex-Preterm vs. Ex-Term adolescents.

METHODS

We compared 43 Ex-Preterm with 26 Ex-Term adolescents using the P50 auditory potential, the Psychomotor Vigilance Task (PVT), a reaction time (RT) test, and Near Infrared Spectroscopy (NIRS).

RESULTS

The mean amplitude (+/-SE) of the P50 amplitude was similar in the Ex-Preterm (1.8+/-1.4 microV) vs. Ex-Term adolescents (1.8+/-0.6 microV, df = 68, F = 0.05, p = 0.8), but the Ex-Preterm group showed a trimodal distribution in amplitude (High, 3.3+/-0.4 microV, df=42.25, F=19.2, p < 0.01; Medium, 1.7+/-0.1 microV, df = 39, F = 0.41, p = 0.53; Low, 0.7+/-0.1 microV, df = 40, F = 49.5, p < 0.01) suggested by statistically significant variance between populations (Kolmogorov-Kuiper test, df = 42.25, F = 5.4, p < 0.01). Mean RT was longer in Ex-Preterm (250+/-8 ms) vs. Ex-Term subjects (200+/-5 ms, df = 68, F = 18.8, p < 0.001). PVT lapses were increased in Ex-Preterm subjects, and varied inversely with P50 amplitude (Overall Mean 17+/-5 lapses, df = 67, F = 5.34, p < 0.05; Low P50 amplitude, 25+/-10, df = 40, F = 8.8, p < 0.01; Medium, 21+/-11, df = 38, F = 5.37, p < 0.05; High, 6+/-2, df = 39, F = 6.78, p < 0.01) vs. Ex-Term subjects (2+/-0.4 lapses, p < 0.01). NIRS levels did not differ statistically, but tended to correlate with P50 amplitude in the Ex-Preterm group.

CONCLUSIONS

These findings suggest differential pre-attentional, attentional and frontal lobe dysfunction in Ex-Preterm adolescents.

SIGNIFICANCE

These measures could provide a means to objectively assess differential dysregulation of arousal and attention in Ex-Preterm adolescents, allowing optimization of therapeutic designs.

Effect of Yakson and Gentle Human Touch versus usual care on urine stress hormones and behaviors in preterm infants: a quasi-experimental study

BACKGROUND

Touching, one of the most developed senses, is proven to relax preterm infants. Yakson is a Korean touching method for healing and relaxation similar to Gentle Human Touch (GHT), which is used in the United States.

OBJECTIVE

The goal of this study was to test the effect of Yakson and GHT on preterm infants' stress and behaviors compared to usual nursing care.

DESIGN

A quasi-experimental study design was used.

PARTICIPANTS

Fifty-nine preterm infants (26-34 weeks gestational age) in the neonatal intensive care unit were chronologically assigned into three groups; Yakson (n=20), GHT (n=20), and control group (n=19).

METHODS

The Yakson and GHT groups each received an intervention for 15min twice a day for 15 days while the control group received usual nursing care. Yakson consists of three five-minute phases: resting the hand on the infant, gentle caressing, and resting the hand again. GHT consists of hand resting for 15min. Twenty-four-hour urine cortisol and norepinephrine samples were collected both before and after the 15-day intervention period. The infants' sleep and awake states were observed before, during, and after each intervention.

RESULTS

Following the intervention period, preterm infants in the Yakson and GHT groups had significantly lower stress hormone levels compared to the control group preterm infants. No significant difference was found in stress hormone levels between Yakson and GHT group preterm infants. After Yakson or GHT, the infants exhibited an increased percentage of sleep states and a decreased percentage of awake and fussy states.

CONCLUSIONS

The findings suggest that Yakson is another touching method that is not aversive or stressful to preterm infants, and which may provide several positive effects on preterm infants.

Analgesic properties of oral sucrose during routine immunizations at 2 and 4 months of age

OBJECTIVE

The purpose of this work was to evaluate the analgesic properties of oral sucrose during routine immunizations in infants at 2 and 4 months of age.

PATIENTS AND METHODS

A prospective, randomized, placebo-controlled clinical trial was conducted at a pediatric ambulatory care clinic. One-hundred healthy term infants scheduled to receive routine immunizations were recruited, randomly stratified into 2- or 4-month study groups, and further randomly assigned to receive 24% oral sucrose and pacifier or the sterile water control solution. The study preparations were administered 2 minutes before the combined diphtheria-tetanus-acellular pertussis, inactivated polio vaccine, and hepatitis B vaccine. Haemophilus influenzae type b vaccine was administered 3 minutes after the combined injection, followed by the pneumococcal conjugate vaccine, 2 minutes after the H. influenzae type b injection. The University of Wisconsin Children's Hospital Pain Scale measured serial acute pain responses for the treatment and control groups at baseline and 2, 5, 7, and 9 minutes after solution administration. Repeated-measures analysis of variance examined between-group differences and within-subject variability of treatment effect on overall pain scores.

RESULTS

Two- and 4-month-old infants receiving oral sucrose (n = 38) displayed reductions in pain scores 2 minutes after solution administration compared with 2- and 4-month-old infants in the placebo group (n = 45). Between-group comparisons for the oral sucrose and placebo groups showed lower pain responses at 5, 7, and 9 minutes after solution administration. The oral sucrose and placebo groups demonstrated their highest mean pain score at 7 minutes, with a mean pain score of 3.8 and 4.8, respectively. At 9 minutes, the placebo group had a mean pain score of 2.91 whereas the mean pain score for the oral sucrose group returned to near baseline, reflecting a 78.5% difference in mean pain score (oral sucrose - placebo) relative to the placebo mean.

CONCLUSIONS

Oral sucrose is an effective, easy-to-administer, short-acting analgesic for use during routine immunizations.

Procedural pain guidelines for the newborn in the United Kingdom

OBJECTIVE

To assess the use of analgesia guidelines for newborn infants in the United Kingdom.

STUDY DESIGN

Postal questionnaire to every neonatal unit in the United Kingdom.

RESULT

A total of 192 of 244 units replied (78.7% response). Most units had a guideline for elective intubation (70%), sedation for ventilation (78%) post-operative pain (when appropriate) (74%). Less prevalent were guidelines for painful minor procedures (35%). Only 33% of units gave a sweet-tasting solution for analgesia before routine painful procedures and 12% used a topical anesthetic cream.

CONCLUSION

Since the last survey in 2000 there has been a modest increased uptake in measures to prevent pain neonatal pain in the United Kingdom, but no pain guideline was present in almost 25% of units and no guideline for routine painful procedures in the majority.

Comparison of pain responses in infants of different gestational ages

BACKGROUND

There is a plethora of infant pain measures; however, none of them have been validated for extremely low for gestational age (ELGA) infants (<27 weeks' gestation). To date, clinicians, researchers and parents use information gleaned from more mature infants to make inferences about pain in ELGA infants. Using physiological or behavioral pain indicators derived from more mature infants may lead to inaccurate assessments and management.

OBJECTIVES

To compare physiological (heart rate, oxygen saturation) and behavioral (9 facial activities, cry) pain indicators of ELGA infants with infants of varying more mature gestational ages (GAs).

METHODS

The aim was to determine the effects of GA on pain response. GA was categorized into four mutually exclusive strata: <27 6/7 weeks, 28-31 6/7 weeks, 32-35 6/7 weeks and >36 weeks. Physiological data during four phases of a routine heel lance were collected by placing disposable ECG electrodes and pulse oximetry probes on the infant's chest. Behavioral data were collected by videotaping facial activities, and cry data were collected by audio recording.

RESULTS

Four facial activities (brow bulge, eye squeeze, nasolabial furrow, vertical mouth stretch) in response to acute pain were present in ELGA infants. Facial activities increased following painful procedures and the magnitude of responses was proportional to GA with the youngest infants (<27 6/7 weeks GA) showing the least amount of change. Decreased oxygen saturation and increased heart rate were associated with the most invasive phase of the heel lance; however, the differences were neither clinically or statistically significant across age groups. Cry was not a sensitive pain indicator in ELGA infants, due to the presence of endotracheal tubes in this high-risk population.

DISCUSSION

ELGA infants have similar pain responses to older infants, but the responses are dampened. Other factors such as severity of illness, frequency of painful procedures or medication use should be examined, as they may influence the pain responses in ELGA infants.

The development of potentially better practices to support the neurodevelopment of infants in the NICU

OBJECTIVE

To review the existing evidence used to identify potentially better care practices that support newborn brain development.

STUDY DESIGN

Literature review.

RESULT

Sixteen potentially better practices are identified and grouped into two operational clinical bundles based upon timing for recommended implementation.

CONCLUSION

Existing evidence supports the implementation of selected care practices that potentially may support newborn brain development.

Do ventilated neonates require pain management?

Mechanical ventilation is a stressful experience in neonates resulting in changes in neuroendocrine parameters, pain scores, and physiologic responses. Assisted ventilation in neonates is presumed to be associated with chronic repetitive pain, which in turn is associated with adverse long-term sequelae. Reasons to routinely sedate ventilated neonates include improved ventilator synchrony, improved pulmonary function, and decreased neuroendocrine responses, including cortisol, beta-endorphine, and catecholamines. Reasons not to treat include the well-known adverse side effects of pain medication, especially the opiates, including hypotension from morphine, chest wall rigidity from fentanyl, and tolerance, dependence, and withdrawal from both opiates and benzodiazepines. Additionally, adverse effects such as death and IVH are not improved with preemptive treatment. Chronic pain assessment is poorly validated and difficult to assess in this population, and most studies have evaluated only acute pain scores. If patients are treated, opiates are the most common class of drugs, with morphine the most well studied. Fentanyl may be advantageous in hypotensive, younger neonates because it has fewer cardiovascular effects. The benzodiazepines, midazolam and lorazepam, have been used in ventilated neonates, but midazolam has been associated with adverse effects in one small study so concern remains regarding its use. Significant gaps in our knowledge exist, especially in regard to long-term effects of treatment, or lack thereof, and in the assessment of the chronic pain associated with assisted ventilation.

Non-pharmacological techniques for pain management in neonates

Significant progress in understanding the physiology, clinical correlates, and consequences of neonatal pain have resulted in greater attention to pain management during neonatal intensive care. A number of nonpharmacological therapies have been investigated, including nonnutritive sucking, with and without sucrose use, swaddling or facilitated tucking, kangaroo care, music therapy, and multi-sensorial stimulation. Although the efficacy of these approaches is clearly evident, they cannot provide analgesia for moderate or severe pain in the neonate. Further, some of these therapies cannot be effectively applied to all populations of critically ill neonates. Acupuncture, an ancient practice in Chinese medicine, has gained increasing popularity for symptom control among adults and older children. Acupuncture may provide an effective nonpharmacological approach for the treatment of pain in neonates, even moderate or severe pain, and should be considered for inclusion in a graduated multidisciplinary algorithm for neonatal pain management.

Neurodevelopmental changes of fetal pain

Pain in the developing fetus is controversial because of the difficulty in measuring and interpreting pain during gestation. It has received increased attention lately because of recently introduced legislation that would require consideration of fetal pain during intentional termination of pregnancy. During development, sensory fibers are abundant by 20 weeks; a functional spinal reflex is present by 19 weeks; connections to the thalamus are present by 20 weeks; and connections to subplate neurons are present by 17 weeks with intensive differentiation by 25 weeks. These cells are important developmentally, but decline as a result of natural apoptosis. Mature thalamocortical projections are not present until 29 to 30 weeks, which has led many to believe the fetus does not experience emotional "pain" until then. Pain requires both nociception and emotional reaction or interpretation. Nociception causes physiologic stress, which in turn causes increases in catecholamines, cortisol, and other stress hormones. Physiological stress is different from the emotional pain felt by the more mature fetus or infant, and this stress is mitigated by pain medication such as opiates. The plasticity of the developing brain makes it vulnerable to the stressors that cause long-term developmental changes, ultimately leading to adverse neurological outcomes. Whereas evidence for conscious pain perception is indirect, evidence for the subconscious incorporation of pain into neurological development and plasticity is incontrovertible. Scientific data, not religious or political conviction, should guide the desperately needed research in this field. In the meantime, it seems prudent to avoid pain during gestation.

Application of Neurobiologic Risk Score in a tertiary care hospital in Pakistan

Many health-care institutions are equipped to provide high-quality care to high-risk neonates. Purpose of this study was to assess validity of a tool using Neurobiologic Risk Score in our setting. This tool is applicable in our setting, although further studies should be initiated to determine development delay.

New insights in the etiology and pathophysiology of irritable bowel syndrome: contribution of neonatal stress models

Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders, characterized by abdominal pain and disturbed defecation that cannot be explained by structural abnormalities. Although IBS symptoms (visceral pain, increased gut permeability, motility alterations) are clearly established, the etiology of this pathology is loosely understood. Nevertheless, clinical studies have reported that some early abuse (physical and psychological) is often associated with IBS development. Thus, loss and separation in the family during childhood may contribute to the IBS development. The recent development of animal models has pointed out the importance of early traumatic experiences in favoring the occurrence of IBS in adult life. Among these different models, neonatal maternal deprivation (NMD), neonatal colonic irritation (inflammatory stimuli), and neonatal colonic pain (rectal distension) have been described to mimic some cardinal features of IBS. The purpose of this review is 3-fold. First, to present the different neonatal stress models. Second, to review the literature on the influence of these early traumatic experiences on the gastrointestinal tract disturbances observed in adult life. Finally, we will also present the mediators and mechanisms involved in gut dysfunction triggered by NMD and probably in IBS.

Ketamine reduces the cell death following inflammatory pain in newborn rat brain

Premature infants experience untreated repetitive pain that may alter their brain development. Effects of ketamine and repetitive pain on cellular death and subsequent behavior were studied in neonatal rats. Rat pups were randomized to undisturbed controls (C), 4% formalin injection (F), ketamine alone (K, 5 mg/kg) or formalin plus ketamine (KF) and were assessed for neuroactivation with Fos protein, cellular death with FluoroJade-B, cognition with the radial arm maze, and pain thresholds with the hot-plate. Greater Fos expression and cell death occurred in F vs. C groups in defined brain areas at 1 and 4 h in F compared with other groups. Cell death was accentuated 3.3-fold in cortical areas and 1.6-fold in subcortical areas in the F compared with the C group following repetitive pain and sacrifice 18-20 h later. These effects were ameliorated by ketamine. Compared with the F group, all other groups demonstrated greater exploratory and rearing behaviors and decreased time for bait consumption at 1-h and 3-h intervals. Significantly greater thermal pain latencies occurred in the KF and F groups. Repetitive neonatal pain accentuates neuronal excitation and cell death in developmentally regulated cortical and subcortical areas, which decreases the acquisition of visual-spatial clues, short-term and long-term memory, and increases pain latencies. Ketamine analgesia mitigates most of these effects.

Chronic pain after childhood groin hernia repair

BACKGROUND

In contrast to the well-described 10% risk of chronic pain affecting daily activities after adult groin hernia repair, chronic pain after childhood groin hernia repair has never been investigated. Studies of other childhood surgery before the age of 3 months suggest a risk of increased pain responsiveness later in life, but its potential relationship to chronic pain in adult life is unknown.

METHODS

This was a nationwide detailed questionnaire study of chronic groin pain in adults having surgery for a groin hernia repair before the age of 5 years (n = 1075).

RESULTS

The response rate was 63.3%. In the 651 patients available for analysis, pain from the operated groin was reported by 88 (13.5%) patients whereof 13 (2.0%) patients reported frequent and moderate or severe pain. Pain occurred primarily when exercising sports or other leisure activities. Patients operated on before the age of 3 months (n = 122) did not report groin pain more often or with higher intensity than other patients did.

CONCLUSIONS

Groin pain in adult patients operated on for a groin hernia in childhood is uncommon and usually mild and occurs in relation to physical activity. Operation before the age of 3 months does not increase the risk of chronic pain.

Safety profile of morphine following surgery in neonates

OBJECTIVE

To determine the effect of morphine on duration of mechanical ventilation, apnoea and hypotension among full-term neonates who underwent thoracic or abdominal surgery in a level III neonatal intensive care unit.

METHOD

Medical records of 82 infants were reviewed retrospectively and data including patient demographics, clinical diagnosis, type of surgery, postoperative opioid administration, duration of mechanical ventilation, hypotension, apnoea and pain scores (premature infant pain profile (PIPP) score) were collected.

RESULT

Sixty-two neonates (76%) received morphine following surgery as a continuous intravenous infusion during the postoperative period. Linear regression analysis showed that morphine dosage and duration were significantly associated with the duration of mechanical ventilation. An increase in morphine infusion rate by 10 microg kg(-1) h(-1) was associated with an increase in the duration of mechanical ventilation by 24 h (P<0.0001) and an increase in morphine duration of 1 hour was associated with a longer duration of mechanical ventilation by 38 min (P<0.0001). Logistic regression analysis showed no association between morphine infusion rate or duration and hypotension. Apnoea was not associated with morphine dosage or duration of infusion in neonates receiving morphine following extubation. Score on the PIPP correlated significantly with morphine infusion rate across time (r=0.47, P<0.01).

CONCLUSION

Postoperative morphine dose and duration may prolong the duration of mechanical ventilation but there are no significant dose-dependent effects on other parameters including apnoea or hypotension following extubation in term neonates. More research is needed to determine the safety profile of morphine for management of pain in non-ventilated neonates.

Opioid analgesia in neonates following cardiac surgery

Pain in the newborn is complex, involving a variety of receptors and mechanisms within the developing nervous system. When pain is generated, a series of sequential neurobiologic changes occur within the central nervous system. If pain is prolonged or repetitive, the developing nervous system could be permanently modified, with altered processing at spinal and supraspinal levels. In addition, pain is associated with a number of adverse physiologic responses that include alterations in circulatory (tachycardia, hypertension, vasoconstriction), metabolic (increased catabolism), immunologic (impaired immune response), and hemostatic (platelet activation) systems. This "stress response" associated with cardiac surgery in neonates could be profound and is associated with increased morbidity and mortality. Neonates undergoing cardiac operations are exposed to extensive tissue damage related to surgery and additional painful stimulation related to endotracheal and thoracostomy tubes that may remain in place for variable periods of time following surgery. In addition, postoperatively neonates endure repeated procedural pain from suctioning of endotracheal tubes, placement of vascular catheters, and manipulation of wounds (eg, sternal closure) and dressings. The treatment and/or prevention of pain are widely considered necessary for humanitarian and physiologic reasons. Improved clinical and developmental outcomes underscore the importance of providing adequate analgesia for newborns who undergo major surgery, mechanical ventilation, and related procedures in the intensive care unit. This article reviews published information regarding opioid administration and associated issues of tolerance and abstinence syndromes (withdrawal) in neonates with an emphasis on those having undergone cardiac surgery.

Neonatal Facial Coding System Scores and Spectral Characteristics of Infant Crying During Newborn Circumcision

OBJECTIVE

To determine the relations between Neonatal Facial Coding System (NFCS) scores and measures of infant crying during newborn circumcision.

METHODS

Video and audio recordings were made of infant facial activity and cry sounds, respectively, during the lysis phase of circumcisions of 44 healthy term males (<3 d of age). All infants received topical analgesia before circumcision. NFCS scores were determined by blinded assistant from video recordings of facial activity. Measures of infant crying were determined via spectrum analysis of audio recordings by a blinded, independent researcher. Pearson product-moment correlations were used to examine relationship between NFCS scores and measures of crying. Principal component factor analysis detected dimensions underlying related measures of crying. Factor scores from a factor analysis were used in stepwise linear regression to predict NFCS scores.

RESULTS

Higher NFCS scores correlated with lower peak fundamental frequency of crying (P<0.01) and with higher amplitudes of crying at peak fundamental frequency and dominant frequency and in overall cry sample (P<0.01). The factor analysis showed 3 significant orthogonal dimensions underlying measures of crying: Power and Velocity (amplitude and rapidity), Pitch of Crying (frequency characteristics), and Infant Arousal (turbulence and intensity) accounting for 42.3%, 17.8%, and 14.6% of variance, respectively. A regression analysis showed all 3 factor scores accounted for significant and separate portions of variance (P<0.001). The best predictor of NFCS score was Power and Velocity (P<0.002), followed by Infant Arousal (P<0.002), and Pitch of Crying (P<0.007).

DISCUSSION

These data provide some of the first known evidence linking specific measures of infant crying with an independent, validated measure of pain.

Prevention and management of pain in the neonate. An update

The prevention of pain in neonates should be the goal of all caregivers, 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 our 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. Every health care facility caring for neonates should implement an effective pain-prevention program, which includes strategies for routinely assessing pain, minimizing the number of painful procedures performed, effectively using pharmacologic and nonpharmacologic therapies for the prevention of pain associated with routine minor procedures, and eliminating pain associated with surgery and other major procedures.

Attention behaviour and hyperactivity at age 4 and duration of breast-feeding

AIM

The relation of longer duration of breast-feeding to cognitive development was been demonstrated in several previous studies, however its potential impact on behaviour is unknown. We assess which behavioural areas (executive function, social competence, attention behaviour and hyperactivity) are related to long-term breast-feeding in young children.

METHODS

Two prospective population-based birth cohorts, one from the island of Menorca (N = 421) and the second from Ribera d'Ebre county (N = 79) in Spain were followed up at the age of 4 years during a two year period (2001-2003). Children were assessed by three psychologists and their respective teachers for neuropsychological functions (McCarthy test), attention-hyperactivity behaviours (Attention-Deficit Hyperactivity Disorder Criteria of DSM-IV) and social behaviour (California Preschool Social Competence Scale).

RESULTS

Long-term breast-feeding was associated with executive function scores (an increase of 4.9 points after breast-feeding >20 weeks), and the improvement of social competence scores (relative risk for being in the poorest 20%, RR = 0.57; 0.52-0.66, after >12 weeks) and attention-deficit hyperactivity symptom scores (RR = 0.56; 0.37-0.85, after >12 weeks). All three outcomes remained significant when included as covariates in the regression models.

CONCLUSION

Long-term breast-feeding was found to be associated with fewer attention and hyperactivity symptoms and an improvement in related behavioural areas (neuropsychological and socio-behavioural outcomes).

Relationship between opioid therapy, tissue-damaging procedures, and brain metabolites as measured by proton MRS in asphyxiated term neonates

To examine the effects of opioid and tissue-damaging procedures (TDPs) [i.e. procedures performed in the neonatal intensive care unit (NICU) known to result in pain, stress, and tissue damage] on brain metabolites, we reviewed the medical records of 28 asphyxiated term neonates (eight opioid-treated, 20 non-opioid treated) who had undergone magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy (MRS) within the first month of life as well as eight newborns with no clinical findings of asphyxial injury. We found that lower creatine (Cr), myoinositol (Ins), and N-acetylaspartate (NAA)/choline (Cho) (p < or = 0.03) and higher Cho/Cr and glutamate/glutamine (Glx) Cr (p < or = 0.02) correlated with increased TDP incidence in the first 2 d of life (DOL). We also found that occipital gray matter (OGM) NAA/Cr was decreased (p = 0.03) and lactate (Lac) was present in a significantly higher amount (40%; p = 0.03) in non-opioid-treated neonates compared with opioid-treated neonates. Compared with controls, untreated neonates showed larger changes in more metabolites in basal ganglia (BG), thalami (TH), and OGM with greater significance than treated neonates. Our data suggest that TDPs affect spectral metabolites and that opioids do not cause harm in asphyxiated term neonates exposed to repetitive TDPs in the first 2-4 DOL and may provide a degree of neuroprotection.

Psychometric testing of a Norwegian version of the Premature Infant Pain Profile: an acute pain assessment tool. A clinical validation study

As neonates are submitted to pain, assessing the pain is crucial in effective pain control. The Premature Infant Pain Profile, an acute measurement tool combining physiological, behavioural and contextual indicators, was translated into Norwegian and tested clinically. The purpose was to establish construct validity, interrater reliability and internal consistency. In addition, the effect of sucrose as pain analgesia was tested in neonates >or= 36 weeks of gestational age. In a known-groups comparisons design with repeated measures, 111 consecutive neonates, preterm and term, were all observed at baseline, non-pain and pain event. Neonates in the neonatal unit received sucrose at pain event. A significant interaction effect of gestational age and events was found in the sucrose neonates. A significant interaction effect was detected from sucrose and event type for neonates from 36 weeks. The internal consistency of the six-item score was acceptable. A correlation coefficient of 0.89-0.97 was obtained for interrater reliability. The Norwegian version of the Premature Infant Pain Profile seems to be a reliable and valid instrument for pain assessment in neonates.

A new model of neonatal stress which produces lasting neurobehavioral effects in adult rats

BACKGROUND

During critical care in neonatal intensive care units (NICU), infants experience stressors and treatments that may produce lasting effects on adult health. An animal model simulating the NICU experience is needed to understand the impact of specific neonatal stressors.

OBJECTIVE

We combined approaches to develop a neonatal rat model simulating NICU stressors in order to examine the hypothesis that early stress and morphine sulfate (MS) exposure would affect development and alter adult behavior.

METHODS

Rat pups were exposed to stressors and given twice daily MS injections (2 mg/kg s.c.) for 5 days (postnatal days 3-7). Stress included daily maternal separation (from 08.00 to 16.00 h), hand feedings, a daily hypoxia/hyperoxia episode (100% N(2) for 8 min, then 100% O(2) for 4 min), and cold exposure (4 degrees C for 20 min/day). Five treatment groups were formed: (1) 'control control' (dam reared and untreated); (2) control vehicle; (3) stress vehicle; (4) control morphine, and (5) stress morphine. Early growth and developmental indices were measured. Adult neurobehavioral tests were paw flick, passive avoidance, and forced swimming. Neonatal MS pharmacokinetics, neonatal and adult corticosterone levels, and adult hematocrit and blood pressure values were measured.

RESULTS

Neonatal stress significantly increased the mortality. Neonatal stress and MS treatment slowed early growth. Neonatal MS impaired passive avoidance learning and increased frequency, duration, and distance of forced swimming. There were no differences in corticosterone, hematocrit, or blood pressure values.

CONCLUSIONS

This model simulates NICU stressors and enables measurement of acute physiological and long-term neurobehavioral indices. Neonatal MS treatment impaired the adult cognitive functioning.

Topical lidocaine and oral acetaminophen provide similar analgesia for myringotomy and tube placement in children

PURPOSE

Preoperative oral acetaminophen (30 mg x kg(-1)) was compared with topical 2% lidocaine ear drops for postoperative analgesia following bilateral myringotomy and tube placement (BMT) in children.

METHODS

In a randomized, prospective, double-blind trial, we studied 124 patients, six months to eight years, ASA physical status I or II, undergoing elective BMT under general anesthesia. The patients in Group I received acetaminophen 30 mg x kg(-1) orally in a grape flavoured syrup 30 to 60 min before surgery and 0.9% saline drops (placebo) in each ear upon insertion of tympanostomy tube. Patients in Group II received a placebo (grape flavoured syrup) before surgery and 2% lidocaine, 0.5 mL in each ear when ear tubes were inserted. Postoperative pain assessments were recorded every five minutes in the postanesthesia care unit, and every 15 min in the day care surgical unit (DCSU) using the modified Children's Hospital of Eastern Ontario pain scale (mCHEOPS), a ten-point scale. Pain at home was documented by parents using a 0 (no pain) to 10 (worst pain imaginable) scale.

RESULTS

The median (range) mCHEOPS scores in the DCSU at 15 and 30 min were similar, i.e., 5 (4-9) in the acetaminophen group and 4 (4-8) in the lidocaine group. The proportion of patients receiving supplemental analgesics in the 24 hr following surgery was similar in both groups (45% and 42% respectively).

CONCLUSION

Topical lidocaine and oral acetaminophen in a dose of 30 mg x kg(-1) provide similar analgesia following BMT.

Pharmacological therapy for analgesia and sedation in the newborn

Rapid advances have been made in the use of pharmacological analgesia and sedation for newborns requiring neonatal intensive care. Practical considerations for the use of systemic analgesics (opioids, non-steroidal anti-inflammatory agents, other drugs), local and topical anaesthetics, and sedative or anaesthetic agents (benzodiazepines, barbiturates, other drugs) are summarised using an evidence-based medicine approach, while avoiding mention of the underlying basic physiology or pharmacology. These developments have inspired more humane approaches to neonatal intensive care. Despite these advances, little is known about the clinical effectiveness, immediate toxicity, effects on special patient populations, or long-term effects after neonatal exposure to analgesics or sedatives. The desired or adverse effects of drug combinations, interactions with non-pharmacological interventions or use for specific conditions also remain unknown. Despite the huge gaps in our knowledge, preliminary evidence for the use of neonatal analgesia and sedation is available, but must be combined with a clear definition of clinical goals, continuous physiological monitoring, evaluation of side effects or tolerance, and consideration of long-term clinical outcomes.

Prevention and management of pain in the neonate: an update

The prevention of pain in neonates should be the goal of all caregivers, 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 our 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. Every health care facility caring for neonates should implement an effective pain-prevention program, which includes strategies for routinely assessing pain, minimizing the number of painful procedures performed, effectively using pharmacologic and nonpharmacologic therapies for the prevention of pain associated with routine minor procedures, and eliminating pain associated with surgery and other major procedures.

NMDA receptors promote survival in somatosensory relay nuclei by inhibiting Bax-dependent developmental cell death

Naturally occurring cell death is a universal feature of developing nervous systems that plays an essential role in determining adult brain function. Yet little is known about the decisions that select a subset of CNS neurons for survival and cause others to die. We report that postnatal day 0 NMDA receptor subunit 1 (NMDAR1) knockout mice display an approximately 2-fold increase in cell death in the brainstem trigeminal complex (BSTC), including all four nuclei that receive somatosensory inputs from the face (principalis, oralis, interpolaris, and caudalis). Treatment with the NMDA receptor antagonist dizocilpine maleate (MK-801) for 24 h before birth also caused an increase in cell death that reached statistical significance in two of the four nuclei (oralis and interpolaris). The neonatal sensitivity to NMDA receptor hypofunction in the BSTC, and in its main thalamic target, the ventrobasal nucleus (VB), coincides with the peak of naturally occurring cell death and trigeminothalamic synaptogenesis. At embryonic day 17.5, before the onset of these events, NMDAR1 knockout does not affect cell survival in either the BSTC or the VB. Immunostaining for active caspase-3 and the neuronal marker Hu specifically confirms the presence of dying neurons in the BSTC and the VB of NMDAR1 knockout neonates. Finally, genetic deletion of Bax rescues these structures from the requirement for NMDA receptors to limit naturally occurring cell death. Taken together, the results indicate that NMDA receptors play a survival role for somatosensory relay neurons during synaptogenesis by inhibiting Bax-dependent developmental cell death.

Time-Dependent Alterations in Ethanol Intake in Male Wistar Rats Exposed to Short and Prolonged Daily Maternal Separation in a 4-Bottle Free-Choice Paradigm

BACKGROUND

Previous studies have shown that maternal separation can be used in animal studies of early environmental influence on adult ethanol intake. These studies have shown that short daily separations result in low ethanol intake, whereas prolonged separations relate to an enhanced risk for a high ethanol intake. The aim of the present study was to further examine the long-term effects of early-life events on ethanol intake.

METHODS

Rat pups were exposed to 15 minutes (MS15) or 360 minutes (MS360) of daily maternal separation during postnatal days 1 to 21 or kept under normal animal facility rearing (AFR) conditions. In adulthood, male rats were given free access to 5, 10, and 20% ethanol, in addition to water, in a 4-bottle-choice paradigm.

RESULTS

No differences in total ethanol intake or preference between the 3 experimental groups were found. The 54-day drinking period was divided into acquisition, stabilization, and maintenance phases for analysis of time and group differences. The MS15 rats increased ethanol intake over time; they mostly consumed 5% ethanol and had a low intake of 20% ethanol throughout the experiment. MS360 rats increased ethanol intake, changed preference from 5% to 20% ethanol, and had a higher increase in intake of 20% ethanol over time. The ethanol intake and preference in the AFR rats were more similar to that of the MS360 rats.

CONCLUSIONS

Time-dependent changes were observed in the preferred choice of low versus high ethanol concentrations in MS15 and MS360 rats. The results support previous findings suggesting that MS15 can be used as a model for environmental protective factors and that MS360 represents a risk environment for acquisition of a high adult ethanol intake.

Experience with remifentanil in neonates and infants

Remifentanil is a relatively new synthetic opioid, which is not licensed worldwide for neonates and infants. Because of its unique pharmacokinetic properties with a short recovery profile, it could be the ideal opioid for neonates and infants, who are especially sensitive to respiratory depression by opioids. Therefore, we conducted a MEDLINE search on all articles dealing with the use of remifentanil in this important subgroup of patients. Most experience with remifentanil in neonates and infants is as maintenance anaesthesia during surgery. In approximately 300 neonates and infants, remifentanil proved to be an effective and safely used opioid for this indication. However, very limited data exist on remifentanil for analgesia and sedation of mechanically ventilated paediatric intensive care patients. Further research with remifentanil in neonates and infants should focus on this group of patients because remifentanil, with its very short context-sensitive half-life, could result in shorter extubation times compared with commonly used opioids such as morphine or fentanyl.

Effects of aging on current vocalization threshold in mice measured by a novel nociception assay

BACKGROUND

Age-related changes in nociception have been extensively studied in the past decades. However, it remains unclear whether in addition to the increased incidence of chronic illness, age-related changes in nociception contribute to increased prevalence of pain in the elderly. Although a great deal of evidence suggests that nociception thresholds increase with aging, other studies yield disparate results. The aim of this investigation was to longitudinally determine the effect of aging on nociception.

METHODS

The authors developed a nociception assay for mice using electrical stimuli at 2,000, 250, and 5 Hz that reportedly stimulate Abeta, Adelta, and C sensory nerve fibers, respectively. A system was designed to automate a method that elicits and detects pain-avoiding behavior in mice. Using a Latin square design, the authors measured current vocalization thresholds serially over the course of mice's life span.

RESULTS

For 2,000-Hz (Abeta), 250-Hz (Adelta), and 5-Hz (C) electrical stimuli, current vocalization thresholds first decreases and then increases with aging following a U-shaped pattern (P < 0.001). In addition, average current vocalization thresholds at youth and senescence are significantly higher than those at middle age for the 250-Hz (Adelta) and 5-Hz (C fiber) electrical stimulus (P < 0.05).

CONCLUSIONS

Using a novel and noninjurious nociception assay, the authors showed that over the life span of mice, current vocalization threshold to electrical stimuli changes in a U-shaped pattern. The findings support the notion that age-related changes in nociception are curvilinear, and to properly study and treat pain, the age of subjects should be considered.

Maternal separation alters drug intake patterns in adulthood in rats

Maternal separation/handling (MS/H) is an animal model of early life stress that causes profound neurochemical and behavioral alterations in pups that persist into adulthood. Many recent studies have used the MS/H model to study changes in drug effects in adulthood that are linked to behavioral treatments and stressors in the perinatal period. The drug effects focused on in this review are the reinforcing properties of the abused drugs, cocaine and alcohol. A striking finding is that variations in maternal separation and handling cause changes in ethanol and cocaine self-administration. Further, these changes indicate that various manipulations in the perinatal period can have long lasting effects of interest to biochemical pharmacologists. This article will review recent studies on ethanol and cocaine self-administration using the MS/H model and the neurochemical alterations that may play a role in the effects of MS/H on ethanol and cocaine self-administration. Studying the MS/H model can provide important clues into the vulnerability to drug abuse and perhaps identify a crucial window of opportunity for therapeutic intervention.

Pain perception development and maturation

Newborn infants are not small adults. The pharmacokinetics and dynamics of analgesic drugs are immature at birth. Volumes of distribution, drug clearances, side-effects and drug efficacy all differ in newborns as compared to adults. Interestingly, these parameters develop before birth and during the postnatal period, reaching adult values after a period of months or years. This means that clinicians should anticipate on pharmacokinetic/pharmacodynamic (PK/PD) changes in newborns with increasing post-conceptual age. The ability to perceive pain might also be immature at birth. Lower pain thresholds due to the absence of inhibitory descending spinothalamic fibers and a not yet fully developed cortical pain memory system are points of interest for our understanding of differences in pain perception in the newborn infant. Although this is a relatively unexplored area of research in humans, we will discuss the maturation and development of neonatal pain experience and perception in this paper.

Long-term consequences of pain in human neonates

The low tactile threshold in preterm infants when they are in the neonatal intensive care unit (NICU), while their physiological systems are unstable and immature, potentially renders them more vulnerable to the effects of repeated invasive procedures. There is a small but growing literature on pain and tactile responsivity following procedural pain in the NICU, or early surgery. Long-term effects of repeated pain in the neonatal period on neurodevelopment await further research. However, there are multiple sources of stress in the NICU, which contribute to inducing high overall 'allostatic load', therefore determining specific effects of neonatal pain in human infants is challenging.

Does regular massage from late pregnancy to birth decrease maternal pain perception during labour and birth?—A feasibility study to investigate a programme of massage, controlled breathing and visualization, from 36 weeks of pregnancy until birth

The present study was undertaken to produce a detailed specification of a programme of massage, controlled breathing and visualization performed regularly by birth partners, from 36 weeks gestation and assisted by a trained professional, following hospital admission during labour and birth. As current research on massage interventions for pain relief in labour is poorly characterized, we began by undertaking a feasibility study on an established massage programme [Goldstone LA. Massage as an orthodox medical treatment past and future. Complementary Therapies in Nursing & Midwifery. 2000;6:169-75]. The intervention was designed in light of experimental findings that repeated massage sessions over 14 days increases pain threshold, by an interaction between oxytocin and opioid neurons [Lund I, Yu L-C, Uvnas-Moberg K, Wang J, Yu C, Kurosawa M, et al. Repeated massage-like stimulation induces long-term effects on nociception: contribution of oxytocinergic mechanisms. European Journal of Neuroscience 2002;16:330-8]. A 4 week time-frame was selected to coincide with a physiological increase in maternal pain threshold [Cogan R, Spinnato JA. Pain and Discomfort Thresholds in Late Pregnancy. Pain 1986;27:63-8, Whipple B, Josimovich JB, Komisaruk BR. Sensory thresholds during the antepartum, intrapartum, and postpartum periods. International Journal of Nursing Studies 1990;27(3):213-21, Gintzler AR, Komisaruk BR. Analgesia is produced by uterocervical mechano-stimulation in rats: roles of afferent nerves and implications for analgesia of pregnancy and parturition. Brain Research 1991;566:299-302, Gintzler AR, Liu N-J. The maternal spinal cord: biochemical and physiological correlates of steroid-activated antinociceptive processes. In: Russell JA, Douglas AJ, Windle RJ, Ingram CD, editors., Progress in Brain Research. Volume 133. The Maternal Brain. Neurobiological and Neuroendocrine adaptation and disorders in pregnancy and postpartum. Amsterdam: Elsevier Science, 2001. p. 83-97]. The main objective was to measure the effects of the programme on maternal pain perception during labour and birth. To detect any effect of massage during labour, on maternal cortisol and catecholamines, cord venous blood was taken to measure plasma concentrations following birth. Twenty-five nulliparous (N) and 10 multiparous (M) women participated in the study. Cortisol values were similar to published studies following labour without massage but pain scores on a Visual Analogue Scale (VAS), at 90min following birth were significantly lower than scores recorded 2 days postpartum [Capogna G, Alahuhta S, Celleno D, De Vlieger H, Moreira J, Morgan B, et al. Maternal expectations and experiences of labour pain and analgesia: a multi-centre study of nulliparous women. International Journal of Obstetric Anaesthesia 1996;5:229-35]. The mean score was 6.6. Previous studies suggest that a reduction from 8.5 to 7.5 would significantly reduce pharmacological analgesia in labour [Capogna G, Alahuhta S, Celleno D, De Vlieger H, Moreira J, Morgan B, et al. Maternal expectations and experiences of labour pain and analgesia: a multi-centre study of nulliparous women. International Journal of Obstetric Anaesthesia 1996;5:229-35].

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.