The pharmacological treatment of neonatal pain

Premedication for less invasive surfactant administration: a narrative review

Less invasive surfactant administration (LISA) is an increasingly popular technique to deliver surfactant to spontaneously breathing preterm infants with respiratory distress syndrome. The optimal method of alleviating the pain and discomfort associated with LISA, either pharmacological or non-pharmacological, while maintaining spontaneous respiration remains unclear. There is limited evidence to guide clinicians, resulting in wide variations in practice. The aim of this article is to summarise the current knowledge and evidence gaps regarding the use of premedication prior to LISA.

Opioid equipotency conversions for hospitalized infants: a systematic review

Hospitalized infants commonly receive opioids to reduce pain and minimize distress during invasive procedures. However, infant neurodevelopment is significantly impacted by cumulative and prolonged opioid exposures. While opioid conversion has been studied extensively in adults, no standardized equipotency opioid conversions exist for hospitalized infants and opioid stewardship efforts are inconsistent. We performed a systematic review to identify opioid dosing conversions commonly used in hospitalized infants <1 year of age, finding fourteen articles which documented or cited a calculation of cumulative opioid exposure. Morphine milligram equivalents (MME) conversion factors varied widely, with nine studies citing conversion equivalent equations commonly used in adults. Efforts to expand safe opioid stewardship to hospitalized infants will require evidence-based consensus for opioid equipotency dose conversions which acknowledge the unique physiology of infants.

Impact of neonatal pain and opiate administration in animal models: A meta-analysis concerning pain threshold

BACKGROUND AND AIM

Neonatal intensive care treatment, including frequently performed painful procedures and administration of analgesic drugs, can have different effects on the neurodevelopment. This systematic review and meta-analysis aimed to investigate the influence of pain, opiate administration, and pre-emptive opiate administration on pain threshold in animal studies in rodents, which had a brain development corresponding to preterm and term infants.

METHODS

A systematic literature search of electronic data bases including CENTRAL (OVID), CINAHL (EBSCO), Embase.com, Medline (OVID), Web of Science, and PsycInfo (OVID) was conducted. A total of 42 studies examining the effect of pain (n = 38), opiate administration (n = 9), and opiate administration prior to a painful event (n = 5) in rodents were included in this analysis.

RESULTS

The results revealed that pain (g = 0.42, 95%CI 0.16-0.67, p = 0.001) increased pain threshold leading to hypoalgesia. Pre-emptive opiate administration had the opposite effect, lowering pain threshold, when compared to pain without prior treatment (g = -1.79, 95%CI -2.71-0.86, p = 0.0001). Differences were found in the meta regression for type of stimulus (thermal: g = 0.66, 95%CI 0.26-1.07, p = 0.001; vs. mechanical: g = 0.13, 95%CI -0.98-1.25, p = 0.81) and gestational age (b = -1.85, SE = 0.82, p = 0.027). In addition, meta regression indicated an association between higher pain thresholds and the amount of cumulative pain events (b = 0.06, SE = 0.03, p = 0.05) as well as severity of pain events (b = 0.94, SE = 0.28, p = 0.001).

CONCLUSION

Neonatal exposure to pain results in higher pain thresholds. However, caution is warranted in extrapolating these findings directly to premature infants. Further research is warranted to validate similar effects in clinical contexts and inform evidence-based practices in neonatal care.

Opioids for procedural pain in neonates

BACKGROUND

Neonates might be exposed to numerous painful procedures due to diagnostic reasons, therapeutic interventions, or surgical procedures. Options for pain management include opioids, non-pharmacological interventions, and other drugs. Morphine, fentanyl, and remifentanil are the opioids most often used in neonates. However, negative impact of opioids on the structure and function of the developing brain has been reported.

OBJECTIVES

To evaluate the benefits and harms of opioids in term or preterm neonates exposed to procedural pain, compared to placebo or no drug, non-pharmacological intervention, other analgesics or sedatives, other opioids, or the same opioid administered by a different route.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was December 2021.

SELECTION CRITERIA

We included randomized controlled trials conducted in preterm and term infants of a postmenstrual age (PMA) up to 46 weeks and 0 days exposed to procedural pain where opioids were compared to 1) placebo or no drug; 2) non-pharmacological intervention; 3) other analgesics or sedatives; 4) other opioids; or 5) the same opioid administered by a different route.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were pain assessed with validated methods and any harms. We used a fixed-effect model with risk ratio (RR) for dichotomous data and mean difference (MD) for continuous data, and their confidence intervals (CI). We used GRADE to assess the certainty of the evidence for each outcome.

MAIN RESULTS

We included 13 independent studies (enrolling 823 newborn infants): seven studies compared opioids to no treatment or placebo (the main comparison in this review), two studies to oral sweet solution or non-pharmacological intervention, and five studies (of which two were part of the same study) to other analgesics and sedatives. All studies were performed in a hospital setting. Opioids compared to placebo or no drug Compared to placebo, opioids probably reduce pain score assessed with the Premature Infant Pain Profile (PIPP)/PIPP-Revised (PIPP-R) scale during the procedure (MD -2.58, 95% CI -3.12 to -2.03; 199 participants, 3 studies; moderate-certainty evidence); may reduce Neonatal Infant Pain Scale (NIPS) during the procedure (MD -1.97, 95% CI -2.46 to -1.48; 102 participants, 2 studies; low-certainty evidence); and may result in little to no difference in pain score assessed with the Douleur Aiguë du Nouveau-né (DAN) scale one to two hours after the procedure (MD -0.20, 95% CI -2.21 to 1.81; 42 participants, 1 study; low-certainty evidence). The evidence is very uncertain about the effect of opioids on pain score assessed with the PIPP/PIPP-R scale up to 30 minutes after the procedure (MD 0.14, 95% CI -0.17 to 0.45; 123 participants, 2 studies; very low-certainty evidence) or one to two hours after the procedure (MD -0.83, 95% CI -2.42 to 0.75; 54 participants, 2 studies; very low-certainty evidence). The evidence is very uncertain about the effect of opioids on episodes of bradycardia (RR 3.19, 95% CI 0.14 to 72.69; 172 participants, 3 studies; very low-certainty evidence). Opioids may result in an increase in episodes of apnea compared to placebo (RR 3.15, 95% CI 1.08 to 9.16; 199 participants, 3 studies; low-certainty evidence): with one study reporting a concerning increase in severe apnea (RR 7.44, 95% CI 0.42 to 132.95; 31 participants, 1 study; very low-certainty). The evidence is very uncertain about the effect of opioids on episodes of hypotension (RR not estimable, risk difference 0.00, 95% CI -0.06 to 0.06; 88 participants, 2 studies; very low-certainty evidence). No studies reported parent satisfaction with care provided in the neonatal intensive care unit (NICU). Opioids compared to non-pharmacological intervention The evidence is very uncertain about the effect of opioids on pain score assessed with the Crying Requires oxygen Increased vital signs Expression Sleep (CRIES) scale during the procedure when compared to facilitated tucking (MD -4.62, 95% CI -6.38 to -2.86; 100 participants, 1 study; very low-certainty evidence) or sensorial stimulation (MD 0.32, 95% CI -1.13 to 1.77; 100 participants, 1 study; very low-certainty evidence). The other main outcomes were not reported. Opioids compared to other analgesics or sedatives The evidence is very uncertain about the effect of opioids on pain score assessed with the PIPP/PIPP-R during the procedure (MD -0.29, 95% CI -1.58 to 1.01; 124 participants, 2 studies; very low-certainty evidence); up to 30 minutes after the procedure (MD -1.10, 95% CI -2.82 to 0.62; 12 participants, 1 study; very low-certainty evidence); and one to two hours after the procedure (MD -0.17, 95% CI -2.22 to 1.88; 12 participants, 1 study; very low-certainty evidence). No studies reported any harms. The evidence is very uncertain about the effect of opioids on episodes of apnea during (RR 3.27, 95% CI 0.85 to 12.58; 124 participants, 2 studies; very low-certainty evidence) and after the procedure (RR 2.71, 95% CI 0.11 to 64.96; 124 participants, 2 studies; very low-certainty evidence) and on hypotension (RR 1.34, 95% CI 0.32 to 5.59; 204 participants, 3 studies; very low-certainty evidence). The other main outcomes were not reported. We identified no studies comparing different opioids (e.g. morphine versus fentanyl) or different routes for administration of the same opioid (e.g. morphine enterally versus morphine intravenously).

AUTHORS' CONCLUSIONS

Compared to placebo, opioids probably reduce pain score assessed with PIPP/PIPP-R scale during the procedure; may reduce NIPS during the procedure; and may result in little to no difference in DAN one to two hours after the procedure. The evidence is very uncertain about the effect of opioids on pain assessed with other pain scores or at different time points. The evidence is very uncertain about the effect of opioids on episodes of bradycardia, hypotension or severe apnea. Opioids may result in an increase in episodes of apnea. No studies reported parent satisfaction with care provided in the NICU. The evidence is very uncertain about the effect of opioids on any outcome when compared to non-pharmacological interventions or to other analgesics. We identified no studies comparing opioids to other opioids or comparing different routes of administration of the same opioid.

Opioids for procedural pain in neonates

BACKGROUND

Neonates might be exposed to numerous painful procedures due to diagnostic reasons, therapeutic interventions, or surgical procedures. Options for pain management include opioids, non-pharmacological interventions, and other drugs. Morphine, fentanyl, and remifentanil are the opioids most often used in neonates. However, negative impact of opioids on the structure and function of the developing brain has been reported.

OBJECTIVES

To evaluate the benefits and harms of opioids in term or preterm neonates exposed to procedural pain, compared to placebo or no drug, non-pharmacological intervention, other analgesics or sedatives, other opioids, or the same opioid administered by a different route.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was December 2021.

SELECTION CRITERIA

We included randomized controlled trials conducted in preterm and term infants of a postmenstrual age (PMA) up to 46 weeks and 0 days exposed to procedural pain where opioids were compared to 1) placebo or no drug; 2) non-pharmacological intervention; 3) other analgesics or sedatives; 4) other opioids; or 5) the same opioid administered by a different route.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were pain assessed with validated methods and any harms. We used a fixed-effect model with risk ratio (RR) for dichotomous data and mean difference (MD) for continuous data, and their confidence intervals (CI). We used GRADE to assess the certainty of the evidence for each outcome.

MAIN RESULTS

We included 13 independent studies (enrolling 823 newborn infants): seven studies compared opioids to no treatment or placebo (the main comparison in this review), two studies to oral sweet solution or non-pharmacological intervention, and five studies (of which two were part of the same study) to other analgesics and sedatives. All studies were performed in a hospital setting. Opioids compared to placebo or no drug Compared to placebo, opioids probably reduce pain score assessed with the Premature Infant Pain Profile (PIPP)/PIPP-Revised (PIPP-R) scale during the procedure (MD -2.58, 95% CI -3.12 to -2.03; 199 participants, 3 studies; moderate-certainty evidence); may reduce Neonatal Infant Pain Scale (NIPS) during the procedure (MD -1.97, 95% CI -2.46 to -1.48; 102 participants, 2 studies; low-certainty evidence); and may result in little to no difference in pain score assessed with the Douleur Aiguë du Nouveau-né (DAN) scale one to two hours after the procedure (MD -0.20, 95% CI -2.21 to 1.81; 42 participants, 1 study; low-certainty evidence). The evidence is very uncertain about the effect of opioids on pain score assessed with the PIPP/PIPP-R scale up to 30 minutes after the procedure (MD 0.14, 95% CI -0.17 to 0.45; 123 participants, 2 studies; very low-certainty evidence) or one to two hours after the procedure (MD -0.83, 95% CI -2.42 to 0.75; 54 participants, 2 studies; very low-certainty evidence). No studies reported any harms. The evidence is very uncertain about the effect of opioids on episodes of bradycardia (RR 3.19, 95% CI 0.14 to 72.69; 172 participants, 3 studies; very low-certainty evidence). Opioids may result in an increase in episodes of apnea compared to placebo (RR 3.15, 95% CI 1.08 to 9.16; 199 participants, 3 studies; low-certainty evidence). The evidence is very uncertain about the effect of opioids on episodes of hypotension (RR not estimable, risk difference 0.00, 95% CI -0.06 to 0.06; 88 participants, 2 studies; very low-certainty evidence). No studies reported parent satisfaction with care provided in the neonatal intensive care unit (NICU). Opioids compared to non-pharmacological intervention The evidence is very uncertain about the effect of opioids on pain score assessed with the Crying Requires oxygen Increased vital signs Expression Sleep (CRIES) scale during the procedure when compared to facilitated tucking (MD -4.62, 95% CI -6.38 to -2.86; 100 participants, 1 study; very low-certainty evidence) or sensorial stimulation (MD 0.32, 95% CI -1.13 to 1.77; 100 participants, 1 study; very low-certainty evidence). The other main outcomes were not reported. Opioids compared to other analgesics or sedatives The evidence is very uncertain about the effect of opioids on pain score assessed with the PIPP/PIPP-R during the procedure (MD -0.29, 95% CI -1.58 to 1.01; 124 participants, 2 studies; very low-certainty evidence); up to 30 minutes after the procedure (MD -1.10, 95% CI -2.82 to 0.62; 12 participants, 1 study; very low-certainty evidence); and one to two hours after the procedure (MD -0.17, 95% CI -2.22 to 1.88; 12 participants, 1 study; very low-certainty evidence). No studies reported any harms. The evidence is very uncertain about the effect of opioids on episodes of apnea during (RR 3.27, 95% CI 0.85 to 12.58; 124 participants, 2 studies; very low-certainty evidence) and after the procedure (RR 2.71, 95% CI 0.11 to 64.96; 124 participants, 2 studies; very low-certainty evidence) and on hypotension (RR 1.34, 95% CI 0.32 to 5.59; 204 participants, 3 studies; very low-certainty evidence). The other main outcomes were not reported. We identified no studies comparing different opioids (e.g. morphine versus fentanyl) or different routes for administration of the same opioid (e.g. morphine enterally versus morphine intravenously).

AUTHORS' CONCLUSIONS

Compared to placebo, opioids probably reduce pain score assessed with PIPP/PIPP-R scale during the procedure; may reduce NIPS during the procedure; and may result in little to no difference in DAN one to two hours after the procedure. The evidence is very uncertain about the effect of opioids on pain assessed with other pain scores or at different time points. No studies reported if any harms occurred. The evidence is very uncertain about the effect of opioids on episodes of bradycardia or hypotension. Opioids may result in an increase in episodes of apnea. No studies reported parent satisfaction with care provided in the NICU. The evidence is very uncertain about the effect of opioids on any outcome when compared to non-pharmacological interventions or to other analgesics. We identified no studies comparing opioids to other opioids or comparing different routes of administration of the same opioid.

Morphine use in the neonatal period and later neuropsychological development: a systematic review

AIM

To identify and evaluate the evidence documenting the association between neonatal morphine and later childhood neuropsychological development.

METHOD

We conducted a systematic literature search of eight electronic databases from inception until June 2019. We included all randomized controlled trials (RCTs) and cohort studies recruiting neonates who received morphine treatment, and measuring neuropsychological development outcomes with a minimum follow-up of 6 months.

RESULTS

Twelve separate reports from three RCTs and five cohort studies met our inclusion criteria. Owing to the small number of the included trials and the variable study designs, a meta-analysis was not performed. The findings from this review indicated that neonatal morphine use had no adverse effects on behaviour, cognition, motor, and executive function development at 8 to 9 years and earlier; except for the inconsistent conclusions on internalizing behavioural problems at 5 to 7 years and cognitive and motor developments at 18 months.

INTERPRETATION

Why a child needs morphine may have a more profound impact on later neuropsychological development than morphine itself. The small number, high heterogeneity, and limitations of the included studies limit confidence in the result of this systematic review.

Valuing life and evaluating suffering in infants with life-limiting illness

In this paper, we explore three separate questions that are relevant to assessing the prudential value of life in infants with severe life-limiting illness. First, what is the value or disvalue of a short life? Is it in the interests of a child to save her life if she will nevertheless die in infancy or very early childhood? Second, how does profound cognitive impairment affect the balance of positives and negatives in a child's future life? Third, if the life of a child with life-limiting illness is prolonged, how much suffering will she experience and can any of it be alleviated? Is there a risk that negative experiences for such a child (suffering) will remain despite the provision of palliative care? We argue that both the subjective and objective components of well-being for children could be greatly reduced if they are anticipated to have a short life that is affected by profound cognitive impairment. This does not mean that their overall well-being will be negative, but rather that there may be a higher risk of negative overall well-being if they are expected to experience pain, discomfort, or distress. Furthermore, we point to some of the practical limitations of therapies aimed at relieving suffering, such that there is a risk that suffering will go partially or completely unrelieved. Taken together, these considerations imply that some life-prolonging treatments are not in the best interests of infants with severe life-limiting illness.

EDIN Scale Implemented by Gestational Age for Pain Assessment in Preterms: A Prospective Study

Background. Chronic neonatal pain can lead to long-term adverse effects on the immature brain. EDIN scale for prolonged pain might not be fully suitable for premature infants. We aimed to test a modified EDIN scale, adding postmenstrual age (PMA) as a sixth item (EDIN6). Methods. In a two-phase prospective study, pain was assessed in all neonates admitted in our NICU. In T1 EDIN was applied; in T2 EDIN6 with additional scores of 2, 1, and 0, respectively, for 25–32, 33–37, and >37 weeks PCA was tested. Scores > 6 suggested pain. The nursing staff was given a questionnaire to evaluate EDIN and EDIN6. Results. A total of 15960 pain assessments were recorded (8693 in T1; 7267 in T2). With EDIN6, cumulative detection of pain almost tripled (117/7267 versus 52/8693, p = 0.001). Main differences were found among less mature categories (50/1472 versus 17/1734, p = 0.001 in PCA 25–32; 26/2606 versus 10/4335, p = 0.001 in PMA 33–37; 41/3189 versus 25/2624, p = 0.26 in PMA > 37). Adequacy of pain assessment in lower PMA was judged “medium-high” in 13,4% of nurses in T1 and 71,4% in T2. Conclusions. EDIN6 may allow improved evaluation of pain in preterm infants.

Pharmacokinetic models of morphine and its metabolites in neonates:: Systematic comparisons of models from the literature, and development of a new meta-model

Morphine is commonly used for pain management in preterm neonates. The aims of this study were to compare published models of neonatal pharmacokinetics of morphine and its metabolites with a new dataset, and to combine the characteristics of the best predictive models to design a meta-model for morphine and its metabolites in preterm neonates. Moreover, the concentration-analgesia relationship for morphine in this clinical setting was also investigated. A population of 30 preterm neonates (gestational age: 23-32weeks) received a loading dose of morphine (50-100μg/kg), followed by a continuous infusion (5-10μg/kg/h) until analgesia was no longer required. Pain was assessed using the Premature Infant Pain Profile. Five published population models were compared using numerical and graphical tests of goodness-of-fit and predictive performance. Population modelling was conducted using NONMEM® and the $PRIOR subroutine to describe the time-course of plasma concentrations of morphine, morphine-3-glucuronide, and morphine-6-glucuronide, and the concentration-analgesia relationship for morphine. No published model adequately described morphine concentrations in this new dataset. Previously published population pharmacokinetic models of morphine, morphine-3-glucuronide, and morphine-6-glucuronide were combined into a meta-model. The meta-model provided an adequate description of the time-course of morphine and the concentrations of its metabolites in preterm neonates. Allometric weight scaling was applied to all clearance and volume terms. Maturation of morphine clearance was described as a function of postmenstrual age, while maturation of metabolite elimination was described as a function of postnatal age. A clear relationship between morphine concentrations and pain score was not established.

Long-Term Effects of Neonatal Morphine Infusion on Pain Sensitivity: Follow-Up of a Randomized Controlled Trial

Short-term and long-term effects of neonatal pain and its analgesic treatment have been topics of translational research over the years. This study aimed to identify the long-term effects of continuous morphine infusion in the neonatal period on thermal pain sensitivity, the incidence of chronic pain, and neurological functioning. Eighty-nine of the 150 participants of a neonatal randomized controlled trial on continuous morphine infusion versus placebo during mechanical ventilation underwent quantitative sensory testing and neurological examination at the age of 8 or 9 years. Forty-three children from the morphine group and 46 children from the placebo group participated in this follow-up study. Thermal detection and pain thresholds were compared with data from 28 healthy controls. Multivariate analyses revealed no statistically significant differences in thermal detection thresholds and pain thresholds between the morphine and placebo groups. The incidence of chronic pain was comparable between both groups. The neurological examination was normal in 29 (76%) of the children in the morphine group and 25 (61%) of the children in the control group (P = .14). We found that neonatal continuous morphine infusion (10 μg/kg/h) has no adverse effects on thermal detection and pain thresholds, the incidence of chronic pain, or overall neurological functioning 8 to 9 years later. Perspective: This unique long-term follow-up study shows that neonatal continuous morphine infusion (10 μg/kg/h) has no long-term adverse effects on thermal detection and pain thresholds or overall neurological functioning. These findings will help clinicians to find the most adequate and safe analgesic dosing regimens for neonates and infants.

Clinical pharmacology of fentanyl in preterm infants. A review

Fentanyl is a synthetic opioid that is very important in anesthetic practice because of its relatively short time to peak analgesic effect and the rapid termination of action after small bolus doses. The objective of this survey is to review the clinical pharmacology of fentanyl in preterm infants. The bibliographic search was performed using PubMed and EMBASE databases as search engines. In addition, the books Neofax: A manual of drugs used in neonatal care and Neonatal formulary were consulted. Fentanyl is N-dealkylated by CYP3A4 into the inactive norfentanyl. Fentanyl may be administered as bolus doses or as a continuous infusion. In neonates, there is a remarkable interindividual variability in the kinetic parameters. In neonates, fentanyl half-life ranges from 317 minutes to 1266 minutes and in adults it is 222 minutes. Respiratory depression occurs when fentanyl doses are >5 μg/kg. Chest wall rigidity may occur in neonates and occasionally is associated with laryngospasm. Tolerance to fentanyl may develop after prolonged use of this drug. Significant withdrawal symptoms have been reported in infants treated with continuous infusion for 5 days or longer. Fentanyl is an extremely potent analgesic and is the opioid analgesic most frequently used in the neonatal intensive care unit.

Glial TLR4 signaling does not contribute to opioid-induced depression of respiration

Opioids activate glia in the central nervous system in part by activating the toll-like receptor 4 (TLR4)/myeloid differentiation 2 (MD2) complex. TLR4/MD2-mediated activation of glia by opioids compromises their analgesic actions. Glial activation is also hypothesized as pivotal in opioid-mediated reward and tolerance and as a contributor to opioid-mediated respiratory depression. We tested the contribution of TLR4 to opioid-induced respiratory depression using rhythmically active medullary slices that contain the pre-Bötzinger Complex (preBötC, an important site of respiratory rhythm generation) and adult rats in vivo. Injection with DAMGO (μ-opioid receptor agonist; 50 μM) or bath application of DAMGO (500 nM) or fentanyl (1 μM) slowed frequency recorded from XII nerves to 40%, 40%, or 50% of control, respectively. This DAMGO-mediated frequency inhibition was unaffected by preapplication of lipopolysaccharides from Rhodobacter sphaeroides (a TLR4 antagonist, 2,000 ng/ml) or (+)naloxone (1-10 μM, a TLR4-antagonist). Bath application of (-)naloxone (500 nM; a TLR4 and μ-opioid antagonist), however, rapidly reversed the opioid-mediated frequency decrease. We also compared the opioid-induced respiratory depression in slices in vitro in the absence and presence of bath-applied minocycline (an inhibitor of microglial activation) and in slices prepared from mice injected (ip) 18 h earlier with minocycline or saline. Minocycline had no effect on respiratory depression in vitro. Finally, the respiratory depression evoked in anesthetized rats by tail vein infusion of fentanyl was unaffected by subsequent injection of (+)naloxone, but completely reversed by (-)naloxone. These data indicate that neither activation of microglia in preBötC nor TLR4/MD2-activation contribute to opioid-induced respiratory depression.

Is there an alternative to continuous opioid infusion for neonatal pain control? A preliminary report of parent/nurse-controlled analgesia in the neonatal intensive care unit

BACKGROUND

Continuous opioid infusion (COI) remains the mainstay of analgesic therapy in the neonatal intensive care unit (NICU). Parent/nurse-controlled analgesia (PNCA) has been accepted as safe and effective for pediatric patients, but few reports include use in neonates. This study sought to compare outcomes of PNCA and COI in postsurgical neonates and young infants.

METHODS

Twenty infants treated with morphine PNCA were retrospectively compared with 13 infants treated with fentanyl COI in a Midwestern pediatric hospital in the United States. Outcome measures included opioid consumption, pain scores, frequency of adverse events, and subsequent methadone use.

RESULTS

The PNCA group (median 6.4 μg · kg(-1) · h(-1) morphine equivalents, range 0.0-31.4) received significantly less opioid (P < 0.001) than the COI group (median 40.0 μg · kg(-1) · h(-1) morphine equivalents; range 20.0-153.3), across postoperative days 0-3. Average daily pain scores (based on 0-10 scale) were low for both groups, but median scores differed nonetheless (0.8 PNCA vs 0.3 COI, P < 0.05). There was no significant difference in the frequency of adverse events or methadone use.

CONCLUSION

Results suggest PNCA may be a feasible and effective alternative to COI for pain management in postsurgical infants in the NICU. Results also suggest PNCA may provide more individualized care for this vulnerable population and in doing so, may potentially reduce opioid consumption; however, more studies are needed.

Endocrinopathies in the cardiac ICU

The past several years have seen an increased appreciation of the potential role of the endocrine system in the recovery process following surgery for congenital heart disease. Many of the hormonal changes following cardiac surgery are adaptive and necessary, whereas activation of proinflammatory cytokine and chemokine responses and some of the metabolic changes following surgery are likely mediators leading to detrimental outcomes. Additionally, other hormonal perturbations may contribute to adverse outcomes. This review examines the pain and the stress response, thyroid function and hyperglycemia following cardiopulmonary bypass (CPB), and the potential role of corticosteroids in the pediatric cardiac critical care unit.

Pharmacological treatment of neonatal pain: in search of a new equipoise

Inadequate management of pain in early human life contributes to impaired neurodevelopmental outcome and alters pain thresholds, pain or stress-related behavior and physiological responses. However, there are also emerging animal experimental data on the impact of exposure to analgo-sedatives on the incidence and extent of neuro-apoptosis. Since this association has also been suggested in humans, the pharmacological treatment of neonatal pain is in search of a new equipoise since these 'conflicting' observations are the main drivers to further reconsider our current treatment regimens. This review focuses on new data concerning clinical pharmacology of morphine, followed by data on more recently introduced opioids like remifentanil and tramadol, locoregional anesthesia and minimally invasive techniques in neonates, and finally with data on intravenous paracetamol. Since the available data are still incomplete, priorities for both clinical management and future research will be proposed.

Does neonatal morphine use affect neuropsychological outcomes at 8 to 9 years of age?

Morphine is widely used to treat severe pain in neonatal intensive care unit patients. Animal studies suggest adverse long-term side effects of neonatal morphine, but a follow-up study of 5-year-old children who participated in a morphine-placebo controlled trial as newborns found no such effects on the child's general functioning. This study indicated that morphine may negatively affect response inhibition, a domain of executive functions. Therefore, we performed a second follow-up study in the same population at the age of 8 to 9 years, focused on the child's general functioning in terms of intelligence, visual motor integration, and behavior and on executive functions. Children in the morphine group showed significantly less externalizing problems according to the parents but more internalizing behavior according to the teachers, but only after adjustment for intelligence quotient (IQ), potential confounders using a propensity score, and additional open-label morphine. Morphine-treated children showed significantly fewer problems with executive functions in daily life as rated by parents for the subscales inhibition and organization of materials and for planning/organizing as rated by the teachers. After adjustment for IQ and the propensity score, executive functioning as rated by the parents remained statistically significantly better in the morphine-treated group. The influence of the additional morphine given was not of a significant influence for any of the outcome variables. Overall, the present study demonstrates that continuous morphine infusion of 10 μg/kg/h during the neonatal period does not harm general functioning and may even have a positive influence on executive functions at 8 to 9 years.

Update on pain assessment in sick neonates and infants

This article describes developments in pain assessment in critically ill neonates and infants during the last 5 to 6 years. Pain assessment instruments show a redundancy of items and a lack of profound psychometric background. Although most research focuses primarily on acute pain, in clinical practice there is also the challenge of assessing prolonged and/or persisting pain. The effectiveness of pain assessment is still a matter of debate and has recently been challenged as a primary end point in analgesia-related trials. Integration of observation of behavior with reliable and specific neurobiology-based parameters remains a challenge.

Pain management in newborns: from prevention to treatment

All neonates in the Neonatal Intensive Care Unit (NICU) or during the first days of life undergo painful and stressful procedures. Epidemiologic studies have shown that pain induced by these procedures is not effectively prevented or is inadequately treated. Pain experienced during the neonatal period may lead to negative outcomes, especially in preterm neonates. Prevention is the first step of pain management, and practical guidelines should be used in the NICU. Assessment must be done with adequate tools that take into account the infant's pathology and gestational age. Distinguishing between acute and prolonged pain is important for both assessment and treatment. The most common drugs that have been studied for the treatment of pain and stress are opioids, hypnosedatives, and NMDA receptor antagonists. Morphine and fentanyl are most frequently used for acute or prolonged pain in the NICU. They have potent analgesic effects and few immediate or long-term adverse effects. Midazolam is a commonly used hypnosedative, but its adverse effects limit its use. Drugs such as propofol and ketamine have been used for acute painful procedures; however, further research is needed to assess their long-term effects. Use of non-pharmacologic pain management techniques has increased in recent years. These methods are easy, inexpensive, and effective in helping newborns recover from painful procedures. Sweet solutions and non-nutritive sucking, breastfeeding, skin-to-skin mother care, swaddling, and facilitated tucking are the most commonly employed and evaluated non-pharmacologic methods. Hospitals should promote and improve parent involvement in pain management. In-service education and well organized hospital teams are crucial for successful implementation of pain protocols in newborns.

Long-lasting neonatal inflammation enhances pain responses to subsequent inflammation, but not peripheral nerve injury in adult rats

The early postnatal period has been suggested to be the vulnerable time for structural and functional reorganization of sensory systems, and painful stimuli at this time may alter neuronal circuits, thereby leading to changes in an individual's response to pain later in life. In the present study, we examined whether inflammatory experience in the early life can affect pain responses to subsequent noxious insults later in life. The two groups of neonatal rats, treated with an inflammatory irritant and untreated, were subjected to inflammation and peripheral nerve injury in adulthood. Neonatal inflammation was induced by injection of complete Freund's adjuvant (CFA, 25 microl) into the hindpaw or tail of newborn rat pups. Adult rats which had suffered from neonatal paw inflammation at P0 were subjected to re-injection of CFA into the paw neonatally exposed to CFA or L5 spinal nerve ligation. Paw thickness and histology of inflamed paw were examined to assess the neonatal inflammation. Adult animals whose tail had been subjected to CFA injection on P3 received tail-innervating nerve injury. The results showed that the neonatal CFA-treated rats suffered from chronic inflammation, confirmed by persistent increase of paw thickness and histological result of inflamed paw. These animals showed enhanced pain responses to re-inflammatory challenge by injection of CFA (200 microl) into the neonatally inflamed paw 8 weeks after birth compared with the neonatally untreated animals. However, neuropathic pain on the hindpaw and the tail which had been induced by peripheral nerve injury in the neonatal CFA-treated group were not different from those of the untreated group. The present data suggest that early neonatal long-lasting inflammation differentially affects pain responses later in life, depending on the types of subsequent noxious insults.

Preemptive morphine analgesia attenuates the long-term consequences of neonatal inflammation in male and female rats

Despite mounting evidence on the importance of pain management in preterm infants, clinical use of analgesics in this population is limited. Our previous studies have shown that neonatal inflammation results in long-term alterations in adult somatosensory thresholds, characterized by decreased baseline nociceptive sensitivity, and enhanced hyperalgesia after a subsequent inflammatory insult. The present studies were conducted to determine whether preemptive morphine attenuates these negative consequences. At P0, pups received an injection of morphine sulfate before an intraplantar injection of 1% carrageenan. Control pups received either saline (SAL) followed by intraplantar carrageenan, morphine sulfate followed by intraplantar SAL, or SAL followed by intraplantar SAL. Preemptive morphine significantly attenuated neonatal injury-induced hypoalgesia in adolescence and adulthood. Similarly, morphine pretreated animals displayed significantly less hyperalgesia and recovered faster from a subsequent inflammatory insult compared with controls. Neonatal morphine had no significant effect on morphine analgesia in adulthood. Interestingly, neonatally injured animals that did not receive morphine displayed a significant rightward shift in the morphine dose-response curve in the absence of peripheral inflammation. Together, these results demonstrate that preemptive morphine significantly attenuates the long-term behavioral impact of neonatal inflammatory injury.

Hepatic tolerance of repeated intravenous paracetamol administration in neonates

INTRODUCTION

An intravenous (i.v.) formulation of paracetamol is available, but reports on its hepatic tolerance in neonates are limited. We therefore assessed hepatic tolerance of i.v. paracetamol in neonates.

METHODS

In a single centre retrospective study, clinical data and hepatic enzyme profiles (ALT, AST, gammaGT) were collected in neonates treated with i.v. paracetamol between January 1, 2006 and October 1, 2007. Hepatic enzyme profiles were retrieved from 2 days before until 2 days after i.v. paracetamol administration. Mann-Whitney U-test was used to compare hepatic enzymes before, during, and after i.v. treatment. Correlations (Spearman rank) of hepatic enzymes with duration of treatment during i.v. administration were investigated.

RESULTS

In 189 cases, 2360 administrations {postmenstrual age 38 (range 30-55) weeks, postnatal age 5 (1-182) days} were documented and 1132 hepatic enzyme observations were available in 149/189 cases. There was no significant increase in ALT, AST, or gammaGT when pretreatment observations (n = 310) were compared with observations during (n = 649) or during with after (n = 173) treatment, nor was there a significant increase during administration.

CONCLUSIONS

This retrospective study on hepatic tolerance provides evidence on safety aspects of i.v. paracetamol in neonates. Future studies should focus on dose-findings and pharmacodynamics of this formulation in neonates.

Pain in children: recent advances and ongoing challenges

Significant advances in the assessment and management of acute pain in children have been made, and are supported by an increase in the availability and accessibility of evidence-based data. However, methodological and practical issues in the design and performance of clinical paediatric trials limit the quantity, and may influence the quality, of current data, which lags behind that available for adult practice. Collaborations within research networks, which incorporate both preclinical and clinical studies, may increase the feasibility and specificity of future trials. In early life, the developing nervous system responds differently to pain, analgesia, and injury, resulting in effects not seen in later life and which may have long-term consequences. Translational laboratory studies further our understanding of developmental changes in nociceptor pathway structure and function, analgesic pharmacodynamics, and the impact of different forms of injury. Chronic pain in children has a negative impact on quality of life, resulting in social and emotional consequences for both the child and the family. Despite age-related differences in many chronic pain conditions, such as neuropathic pain, management in children is often empirically based on data from studies in adults. There is a major need for further clinical research, training of health-care providers, and increased resources, to improve management and outcomes for children with chronic pain.

Early awakening and extubation with remifentanil in ventilated premature neonates

BACKGROUND

Morphine is one of the most commonly used drugs for sedation and analgesia during mechanical ventilation, but its pharmacological profile has limitations, such as prolonged duration of action, especially in premature neonates. Because of its very short context-sensitive half-time, remifentanil has rapid onset and quickly decreases in plasma concentration after interrupting administration. The aim of the present study was to compare a continuous infusion of remifentanil and morphine during mechanical ventilation of premature neonates with respiratory distress syndrome (RDS).

METHODS

Twenty premature neonates (28-34 weeks) with RDS were randomized in a prospective double-blinded study to receive either a continuous infusion of morphine (n = 10) or remifentanil (n = 10) for mechanical ventilation. The length of time to awaken and extubate the neonate after interrupting opioid administration was recorded. We also recorded stress (COMFORT scale), pain response [Neonatal Infant Pain Scale (NIPS)], hemodynamic and ventilatory variables as well as adverse effects secondary to infusion of the specific opioid.

RESULTS

After terminating infusion, the length of time required to awaken and extubate the neonates was 18.9- and 12.1-fold longer, respectively, in the morphine group than in the remifentanil group. Both groups produced good quality sedation and analgesia as evaluated by the NIPS and COMFORT scores. No major side effects were observed.

CONCLUSIONS

Our results show an interesting potential for the use of remifentanil in premature neonates. Remifentanil allowed an adequate level of sedation and analgesia as well as rapid recovery after discontinuation. However, further properly designed clinical trials are needed before it can be generally recommended.

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.

Prospective sonographic evaluation of fentanyl side effects on the neonatal gallbladder

OBJECTIVE

In an effort to minimise the stress and pain of mechanically ventilated neonates, the application of opioids has increased markedly. Abdominal adverse effects of opioid analgesics are constipation and increased pressure in the biliary system. Our aim was to evaluate the impact of continuous intravenous infusion of fentanyl on the volume of the neonatal gallbladder and to assess potential gastrointestinal side effects.

METHODS

We prospectively matched pairs of 40 mechanically ventilated neonates (28-42 gestational weeks) under total parenteral nutrition and midazolam sedation. One group (20 patients) received continuous fentanyl infusions (dose 0.5-2 microg kg(-1) h(-1)) the other group (20 patients) served as controls. Sonographic measurements of gallbladder length, depth and width were performed to calculate gallbladder volume using the ellipsoid method. Repeated ultrasound images, date of meconium release and serum bilirubin levels were documented.

RESULTS

Fentanyl application was not associated with gallbladder sludge/stones, gallbladder hydrops, hyperbilirubinemia or prolonged meconium release. Neonatal gallbladder length, width and volume did not differ significantly (data expressed as mean, standard deviation, median, interquartile range: length (cm) 3.16+/-0.68, 3.3, 0.675 vs 3.06+/-0.62, 3.3, 1.1; P=0.645; width (cm) 1.02+/-0.23, 1.0, 0.28 vs 0.89+/-0.27, 0.9, 0.38, P=0.12; volume (cm(3)) 1.52+/-0.67, 1.7, 0.86 vs 1.22+/-0.77, 1.09, 1.19, P=0.20).

CONCLUSION

In our study fentanyl caused no major complications in the biliary system and intestine of ventilated preterm and term neonates. Sonographic investigations of the gallbladder under fentanyl treatment may be dispensable. Further investigations are required to assess adverse gastrointestinal effects.

Douleur du nouveau-né : traitement pharmacologique

Pain causes numerous physiological changes in neonates. All invasive procedures induce undesirable stress responses; theses responses can, however, be eliminated or reduced by a judicious use of analgesia. Even though a large number of analgesics and sedatives are currently available, most of them have not been studied in the neonate. At present, a precise understanding of the pharmacological mechanisms of analgesics is difficult because many interactions still remain unknown in the term and premature neonate. This article describes the main analgesics and sedative agents used in the neonate: morphine, fentanyl, sufentanil, alfentanil, nalbuphine, ketamine, midazolam, propofol, acetaminophen, and Emla cream. After a review of the literature regarding these drugs, some practical advices and suggestions for the treatment of procedure-induced pain, and background sedation/analgesia for ventilated neonates are given. It is also stated in this article that the best way to soothe pain in neonates is to combine non pharmacological and pharmacological strategies. At the national level, written guidelines should be prepared in order to improve pain management in the neonate.