Hormonal and metabolic stress responses after major surgery in children aged 0-3 years: a double-blind, randomized trial comparing the effects of continuous versus intermittent morphine

Systemic opioid regimens for postoperative pain in neonates

BACKGROUND

Postoperative pain clinical management in neonates has always been a challenging medical issue. Worldwide, several systemic opioid regimens are available for pediatricians, neonatologists, and general practitioners to control pain in neonates undergoing surgical procedures. However, the most effective and safe regimen is still unknown in the current body of literature.

OBJECTIVES

To determine the effects of different regimens of systemic opioid analgesics in neonates submitted to surgery on all-cause mortality, pain, and significant neurodevelopmental disability. Potentially assessed regimens might include: different doses of the same opioid, different routes of administration of the same opioid, continuous infusion versus bolus administration, or 'as needed' administration versus 'as scheduled' administration.

SEARCH METHODS

Searches were conducted in June 2022 using the following databases: Cochrane Central Register of Controlled Trials [CENTRAL], PubMed, and CINAHL. Trial registration records were identified via CENTRAL and an independent search of the ISRCTN registry.

SELECTION CRITERIA

We included randomized controlled trials (RCTs), quasi-randomized, cluster-randomized, and cross-over controlled trials evaluating systemic opioid regimens' effects on postoperative pain in neonates (pre-term or full-term). We considered suitable for inclusion: I) studies evaluating different doses of the same opioid; 2) studies evaluating different routes of administration of the same opioid; 3) studies evaluating the effectiveness of continuous infusion versus bolus infusion; and 4) studies establishing an assessment of an 'as needed' administration versus 'as scheduled' administration.

DATA COLLECTION AND ANALYSIS

According to Cochrane methods, two investigators independently screened retrieved records, extracted data, and appraised the risk of bias. We stratified meta-analysis by the type of intervention: studies evaluating the use of opioids for postoperative pain in neonates through continuous infusion versus bolus infusion and studies assessing the 'as needed' administration versus 'as scheduled' administration. We used the fixed-effect model with risk ratio (RR) for dichotomous data and mean difference (MD), standardized mean difference (SMD), median, and interquartile range (IQR) for continuous data. Finally, we used the GRADEpro approach for primary outcomes to evaluate the quality of the evidence across included studies.

MAIN RESULTS

In this review, we included seven randomized controlled clinical trials (504 infants) from 1996 to 2020. We identified no studies comparing different doses of the same opioid, or different routes. The administration of continuous opioid infusion versus bolus administration of opioids was evaluated in six studies, while one study compared 'as needed' versus 'as scheduled' administration of morphine given by parents or nurses. Overall, the effectiveness of continuous infusion of opioids over bolus infusion as measured by the visual analog scale (MD 0.00, 95% confidence interval (CI) -0.23 to 0.23; 133 participants, 2 studies; I² = 0); or using the COMFORT scale (MD -0.07, 95% CI -0.89 to 0.75; 133 participants, 2 studies; I² = 0), remains unclear due to study designs' limitations, such as the unclear risk of attrition, reporting bias, and imprecision among reported results (very low certainty of the evidence).  None of the included studies reported data on other clinically important outcomes such as all-cause mortality rate during hospitalization, major neurodevelopmental disability, the incidence of severe retinopathy of prematurity or intraventricular hemorrhage, and cognitive- and educational-related outcomes.  AUTHORS' CONCLUSIONS: Limited evidence is available on continuous infusion compared to intermittent boluses of systemic opioids. We are uncertain whether continuous opioid infusion reduces pain compared with intermittent opioid boluses; none of the studies reported the other primary outcomes of this review, i.e. all-cause mortality during initial hospitalization, significant neurodevelopmental disability, or cognitive and educational outcomes among children older than five years old. Only one small study reported on morphine infusion with parent- or nurse-controlled analgesia.

Systemic opioid regimens for postoperative pain in neonates

BACKGROUND

Postoperative pain clinical management in neonates has always been a challenging medical issue. Worldwide, several systemic opioid regimens are available for pediatricians, neonatologists, and general practitioners to control pain in neonates undergoing surgical procedures. However, the most effective and safe regimen is still unknown in the current body of literature.

OBJECTIVES

To determine the effects of different regimens of systemic opioid analgesics in neonates submitted to surgery on all-cause mortality, pain, and significant neurodevelopmental disability. Potentially assessed regimens might include: different doses of the same opioid, different routes of administration of the same opioid, continuous infusion versus bolus administration, or 'as needed' administration versus 'as scheduled' administration.

SEARCH METHODS

Searches were conducted in June 2022 using the following databases: Cochrane Central Register of Controlled Trials [CENTRAL], PubMed, and CINAHL. Trial registration records were identified via CENTRAL and an independent search of the ISRCTN registry.

SELECTION CRITERIA

We included randomized controlled trials (RCTs), quasi-randomized, cluster-randomized, and cross-over controlled trials evaluating systemic opioid regimens' effects on postoperative pain in neonates (pre-term or full-term). We considered suitable for inclusion: I) studies evaluating different doses of the same opioid; 2) studies evaluating different routes of administration of the same opioid; 3) studies evaluating the effectiveness of continuous infusion versus bolus infusion; and 4) studies establishing an assessment of an 'as needed' administration versus 'as scheduled' administration.

DATA COLLECTION AND ANALYSIS

According to Cochrane methods, two investigators independently screened retrieved records, extracted data, and appraised the risk of bias. We stratified meta-analysis by the type of intervention: studies evaluating the use of opioids for postoperative pain in neonates through continuous infusion versus bolus infusion and studies assessing the 'as needed' administration versus 'as scheduled' administration. We used the fixed-effect model with risk ratio (RR) for dichotomous data and mean difference (MD), standardized mean difference (SMD), median, and interquartile range (IQR) for continuous data. Finally, we used the GRADEpro approach for primary outcomes to evaluate the quality of the evidence across included studies.

MAIN RESULTS

In this review, we included seven randomized controlled clinical trials (504 infants) from 1996 to 2020. We identified no studies comparing different doses of the same opioid, or different routes. The administration of continuous opioid infusion versus bolus administration of opioids was evaluated in six studies, while one study compared 'as needed' versus 'as scheduled' administration of morphine given by parents or nurses. Overall, the effectiveness of continuous infusion of opioids over bolus infusion as measured by the visual analog scale (MD 0.00, 95% confidence interval (CI) -0.23 to 0.23; 133 participants, 2 studies; I² = 0); or using the COMFORT scale (MD -0.07, 95% CI -0.89 to 0.75; 133 participants, 2 studies; I² = 0), remains unclear due to study designs' limitations, such as the unclear risk of attrition, reporting bias, and imprecision among reported results (very low certainty of the evidence).  None of the included studies reported data on other clinically important outcomes such as all-cause mortality rate during hospitalization, major neurodevelopmental disability, the incidence of severe retinopathy of prematurity or intraventricular hemorrhage, and cognitive- and educational-related outcomes.  AUTHORS' CONCLUSIONS: Limited evidence is available on continuous infusion compared to intermittent boluses of systemic opioids. We are uncertain whether continuous opioid infusion reduces pain compared with intermittent opioid boluses; none of the studies reported the other primary outcomes of this review, i.e. all-cause mortality during initial hospitalization, significant neurodevelopmental disability, or cognitive and educational outcomes among children older than five years old. Only one small study reported on morphine infusion with parent- or nurse-controlled analgesia.

Design and reporting characteristics of clinical trials investigating sedation practices in the paediatric intensive care unit: a scoping review by SCEPTER (Sedation Consortium on Endpoints and Procedures for Treatment, Education and Research)

OBJECTIVES

To conduct a scoping review of sedation clinical trials in the paediatric intensive care setting and summarise key methodological elements.

DESIGN

Scoping review.

DATA SOURCES

PubMed, Embase, Cumulative Index to Nursing and Allied Health Literature and grey references including ClinicalTrials.gov from database inception to 3 August 2021.

STUDY SELECTION

All human trials in the English language related to sedation in paediatric critically ill patients were included. After title and abstract screening, full-text review was performed. 29 trials were eligible for final analysis.

DATA EXTRACTION

A coding manual was developed and pretested. Trial characteristics were double extracted.

RESULTS

The majority of trials were single centre (22/29, 75.9%), parallel group superiority (17/29, 58.6%), double-blinded (18/29, 62.1%) and conducted in an academic setting (29/29, 100.0%). Trial enrolment (≥90% planned sample size) was achieved in 65.5% of trials (19/29), and retention (≥90% enrolled subjects) in 72.4% of trials (21/29). Protocol violations were reported in nine trials (31.0%). The most commonly studied cohorts were mechanically ventilated patients (28/29, 96.6%) and postsurgical patients (11/29, 37.9%) with inclusion criteria for age ranging from 0±0.5 to 15.0±7.3 years (median±IQR). The median age of enrolled patients was 1.7 years (IQR=4.4 years). Patients excluded from trials were those with neurological impairment (21/29, 72.4%), complex disease (20/29, 69.0%) or receipt of neuromuscular blockade (10/29, 34.5%). Trials evaluated drugs/protocols for sedation management (20/29, 69.0%), weaning (3/29, 10.3%), daily interruption (3/29, 10.3%) or protocolisation (3/29, 10.3%). Primary outcome measures were heterogeneous, as were assessment instruments and follow-up durations.

CONCLUSIONS

There is substantial heterogeneity in methodological approach in clinical trials evaluating sedation in critically ill paediatric patients. These results provide a basis for the design of future clinical trials to improve the quality of trial data and aid in the development of sedation-related clinical guidelines.

The Fluctuations of Melatonin and Copeptin Levels in Blood Serum During Surgical Stress Regarding the Pediatric Population

INTRODUCTION

Copeptin is known to be associated with heart damage, while melatonin is a regulatory hormone related to circadian rhythm and represents the levels of inflammation in the body.

METHODS AND PATIENTS

The aim of the study was to measure in different surgeries the levels of copeptin and melatonin at different times before and after surgery in 56 patients aged from 5 days to 13.6 years. We measured copeptin in 50-microL serum and plasma samples from patients before surgery, immediately after surgery, and 24 hours after surgery. The measured levels are aligned with the published GC / MS data, and the sensitivity of the analysis is such that serum and plasma levels can only be measured by rapid extraction. The measurement was made before surgery, immediately after surgery, and 24 hours after surgery.

RESULTS

The multifactorial statistical analysis revealed a statistically significant difference between the 24-hour postoperative copeptin values in group 1 (mild-moderate gravity surgery) and group 2 (severe surgery) of the severity of the surgery. Post-hoc tests with Tukey correction for age groups in multiple comparisons of the multifactorial analysis revealed a statistically significant difference (p <0.05) between 24-hour postoperative melatonin values in age groups 3 (3-6 years) and 5 (6-12 years old). The age group 3 showed significantly (p <0.05) lower 24 hours postoperative melatonin values compared to the age group 5 (6-12 years). Again, these 3-6-year-olds were more likely to have inflammation due to the severity of the surgery and the presence of inflammation after the surgery.

DISCUSSION

In summary, copeptin is a reliable biomarker for assessing a patient's health both preoperatively and postoperatively. Copeptin and melatonin are two independent agents and are not related to each other, and more studies will be needed with more patients of the same age and with the same underlying disease to assess their diagnostic value. Finally, melatonin could be considered an indicator of inflammation on its own and based on pre-and post-surgery values to determine a patient's health status and take appropriate actions.

Practical approaches to sedation and analgesia in the newborn

The prevention, assessment, and treatment of neonatal pain and agitation continues to challenge clinicians and researchers. Substantial progress has been made in the past three decades, but numerous outstanding questions remain. In this setting, clinicians must establish safe and compassionate standardized practices that consider available efficacy data, long-term outcomes, and research gaps. Novel approaches with limited data must be carefully considered against historic standards of care with robust data suggesting limited benefit and clear adverse effects. This review summarizes available evidence while suggesting practical clinical approaches to pain assessment and avoidance, procedural analgesia, postoperative analgesia, sedation during mechanical ventilation and therapeutic hypothermia, and the issues of tolerance and withdrawal. Further research in all areas represents an urgent priority for optimal neonatal care. In the meantime, synthesis of available data offers clinicians challenging choices as they balance benefit and risk in vulnerable critically ill neonates.

Sedation strategies in children with pediatric acute respiratory distress syndrome (PARDS)

In this review, we discuss the changing landscape of sedation in mechanically ventilated children with pediatric acute respiratory distress syndrome (PARDS). While previous approaches advocated for early and deep sedation with benzodiazepines, emerging literature has highlighted the benefits of light sedation and use of non-benzodiazepine sedating agents, such as dexmedetomidine. Recent studies have emphasized the importance of monitoring multiple factors including, but not limited to, sedation depth, analgesia efficacy, opiate withdrawal, and development of delirium. Through this approach, we hope to improve PARDS outcomes. Overall, more research is needed to further our understanding of the best sedation strategies in children with PARDS.

Evidence-based clinical guidelines on analgesia and sedation in newborn infants undergoing assisted ventilation and endotracheal intubation

AIM

This review informed pain control guidelines for clinicians performing mechanical ventilation, nasal continuous positive airway pressure and endotracheal intubation on term and preterm newborn infants.

METHODS

We reviewed literature published between 1986 and June 2017 on analgesia and sedation during assisted ventilation and before endotracheal intubation in newborn infants admitted to neonatal intensive care units. The subsequent guidelines were developed using the Grading of Recommendations Assessment, Development and Evaluation approach.

RESULTS

Our review produced five strong standard of care recommendations. One, reduce neonatal stress and use nonpharmacological analgesia during invasive ventilation. Two, favour intermittent boluses of opioids, administered after pain scores and before invasive procedures, during short expected periods of mechanical ventilation, mainly in preterm infants affected by respiratory distress syndrome. Three, do not use morphine infusion in preterm infants under 27 gestational weeks. Four, always use algometric scores to titrate analgesic drugs doses. Five, use premedication before endotracheal intubation for a more rapid, less painful, less traumatic and safer manoeuvre. We also developed 30 conditional recommendations on therapeutic options.

CONCLUSION

Our review produced 35 recommendations on standard care and therapeutic options relating to the analgesia and sedation of newborn infants during ventilation and before endotracheal intubation.

Neurotoxicity of Inhalation Anesthetics in the Neonatal Rat Brain: Effects on Behavior and Neurodegeneration in the Piriform Cortex

There is concern that clinical use of anesthetic drugs may cause neurotoxicity in the developing brain and subsequent abnormal neurobehavior. We therefore evaluated neurotoxic effects of inhalation anesthetics in the neonatal rat brain, using in vivo histological and neurobehavioral outcomes. Wistar rats (n=79, postnatal day 15) were subjected to a clinically relevant single exposure of urethane, isoflurane, sevoflurane, or placebo, without surgery. At 48 h and 96 h, behavioral parameters were recorded and the animals were sacrificed. In cryosectioned brains, total cells and dying cells in layer II of the piriform cortex were counted using unbiased stereology. At 48 h, cell numbers in layer II of the piriform cortex of all drug-treated animals were reduced versus controls (p=0.01). The effect persisted at 96 h in isoflurane- and urethane-exposed animals. Piriform cortical layer II neurons undergoing degeneration, detected histologically by pyknotic nuclei and eosinophilic cytoplasm, were increased in the animals treated with isoflurane (1.9 ± 0.7 at 96 h) and urethane (2.4 ± 0.8 at 96 h) versus sevoflurane (0.8 ± 0.3 at 96 h) and controls (0.9 ± 0.2 at 96 h). Sevoflurane- and isoflurane-treated animals exhibited increased activity and decreased suckling compared with controls, and sevoflurane-exposed animals also displayed increased rearing behavior at both timepoints.

Intermittent Versus Continuous and Intermittent Medications for Pain and Sedation After Pediatric Cardiothoracic Surgery; A Randomized Controlled Trial

OBJECTIVES

Compare continuous infusions of morphine and midazolam in addition to intermittent doses with an intermittent only strategy for pain and sedation after pediatric cardiac surgery.

DESIGN

Randomized controlled trial.

SETTING

Advocate Children's Hospital, Oak Lawn, IL.

PATIENTS

Sixty patients 3 months to 4 years old with early extubation after pediatric cardiac surgery.

INTERVENTIONS

Patients received a continuous infusion of morphine and midazolam or placebo for 24 hours. Both groups received intermittent morphine and midazolam doses as needed.

MEASUREMENTS AND MAIN RESULTS

Gender, age, bypass time, and surgical complexity were not different between groups. Scheduled ketorolac and acetaminophen were used in both groups and were not associated with adverse events. The mean, median, and maximum Faces, Legs, Activity, Cry, And Consolability score were not different between groups. There was no significant difference in number of intermittent doses received between groups. The total morphine dose was higher in the continuous/intermittent group (0.90 vs 0.23 mg/kg; p < 0.01). The total midazolam dose was also higher in the continuous/intermittent group (0.90 vs 0.18 mg/kg; p < 0.01). The hospital length of stay was longer in the continuous/intermittent group (8.4 vs 4.9 d; p = 0.04).

CONCLUSIONS

Pain was not better controlled with the addition of continuous infusions of morphine and midazolam when compared with intermittent dosing only. Use of continuous infusions resulted in a significantly higher total dosage of these medications and a longer length of stay.

Oral morphine dosing predictions based on single dose in healthy children undergoing surgery

BACKGROUND

Oral morphine has been proposed as an effective and safe alternative to codeine for after-discharge pain in children following surgery but there are few data guiding an optimum safe oral dose.

AIMS

The aim of this study was to characterize the absorption pharmacokinetics of enteral morphine in order to simulate time-concentration profiles in children given common oral morphine dose regimens.

METHODS

Children (2-6 years, n = 34) undergoing elective surgery and requiring opioid analgesia were randomized to receive preoperative oral morphine (100 mcg·kg^-1 , 200 mcg·kg^-1 , 300 mcg·kg^-1 ). Blood sampling for morphine assay was performed at 30, 60, 90, 120, 180, and 240 min. Morphine serum concentrations were determined by liquid chromatography-mass spectroscopy and pharmacokinetic parameters were calculated using nonlinear mixed effects models. Current data were pooled with published time-concentration profiles from children (n = 1059, age 23 weeks postmenstrual age - 3 years) administered intravenous morphine, to determine oral bioavailability (F), absorption lag time (T_LAG ), and absorption half-time (T_ABS ). These parameter estimates were used to predict concentrations in children given oral morphine (100, 200, 300, 400, 500 mcg·kg^-1 ) at different dosing intervals (3, 4, 5, 6, 8, 12 h).

RESULTS

The oral morphine formulation had F 0.298 (CV 36.5%), T_LAG 0.45 (CV 63.6%) h and T_ABS 0.71 (CV 55%) h. A single-dose morphine 100 mcg·kg^-1 achieved a mean C_MAX 10 mcg·l^-1 . Repeat 4-hourly dosing achieved mean steady-state concentration 13-18 mcg·l^-1 ; concentrations associated with good analgesia after intravenous administration. Serum concentration variability was large ranging from 5 to 55 mcg·l^-1 at steady state.

CONCLUSIONS

Oral morphine 200 mcg·kg^-1 then 100 mcg·kg^-1 4 h or 150 mcg·kg^-1 6 h achieves mean concentrations associated with analgesia. There was high serum concentration variability suggesting that respiration may be compromised in some children given these doses.

Treatment of Pain in Pediatric Patients

A growing body of evidence demonstrates that untreated pain is associated with adverse consequences that can compromise clinical and developmental outcomes in children but that these adverse consequences can be prevented or attenuated by appropriate analgesic therapy. Thus, effective treatment of acute pain must be a clinical priority for children of all ages. Over the past 20 years, extensive pediatric research exploring pain assessment, developmental pharmacology of analgesics, and the clinical use of analgesics has dispelled many myths and misconceptions about pain management in pediatric patients; proven that analgesics can be used safely in neonates, infants, and children; and provided a framework for the development of pediatric pain management guidelines. This article reviews guidelines recommended for managing acute pain in pediatric patients and the treatment options for children experiencing acute pain. Contemporary issues regarding acetaminophen, nonsteroidal anti-inflammatory agents, and opioids are discussed.

Painful procedures and analgesia in the NICU: what has changed in the medical perception and practice in a ten-year period?

OBJECTIVE

To compare the use of analgesia versus neonatologists' perception regarding analgesic use in painful procedures in the years 2001, 2006, and 2011.

METHODS

This was a prospective cohort study of all newborns admitted to four university neonatal intensive care units during one month in 2001, 2006, and 2011. The frequency of analgesic prescription for painful procedures was evaluated. Of the 202 neonatologists, 188 answered a questionnaire giving their opinion on the intensity of pain during lumbar puncture, tracheal intubation, mechanical ventilation, and postoperative period using a 10-cm visual analogic scale (VAS; pain >3cm).

RESULTS

For lumbar puncture, 12% (2001), 43% (2006), and 36% (2011) were performed using analgesia. Among the neonatologists, 40-50% reported VAS >3 for lumbar puncture in all study periods. For intubation, 30% received analgesia in the study periods, and 35% (2001), 55% (2006), and 73% (2011) of the neonatologists reported VAS >3 and would prescribe analgesia for this procedure. As for mechanical ventilation, 45% (2001), 64% (2006), and 48% (2011) of patient-days were under analgesia; 56% (2001), 57% (2006), and 26% (2011) of neonatologists reported VAS >3 and said they would use analgesia during mechanical ventilation. For the first three post-operative days, 37% (2001), 78% (2006), and 89% (2011) of the patients received analgesia and more than 90% of neonatologists reported VAS >3 for major surgeries.

CONCLUSIONS

Despite an increase in the medical perception of neonatal pain and in analgesic use during painful procedures, the gap between clinical practice and neonatologist perception of analgesia need did not change during the ten-year period.

The long-term impact of early life pain on adult responses to anxiety and stress: Historical perspectives and empirical evidence

Approximately 1 in 6 infants are born prematurely each year. Typically, these infants spend 25 days in the Neonatal Intensive Care Unit (NICU) where they experience 10-18 painful and inflammatory procedures each day. Remarkably, pre-emptive analgesics and/or anesthesia are administered less than 25% of the time. Unalleviated pain during the perinatal period is associated with permanent decreases in pain sensitivity, blunted cortisol responses and high rates of neuropsychiatric disorders. To date, the mechanism(s) by which these long-term changes in stress and pain behavior occur, and whether such alterations can be prevented by appropriate analgesia at the time of insult, remains unclear. Work in our lab using a rodent model of early life pain suggests that inflammatory pain experienced on the day of birth blunts adult responses to stress- and pain-provoking stimuli, and dysregulates the hypothalamic pituitary adrenal (HPA) axis in part through a permanent upregulation in central endogenous opioid tone. This review focuses on the long-term impact of neonatal inflammatory pain on adult anxiety- and stress-related responses, and underlying neuroanatomical changes in the context of endogenous pain control and the HPA axis. These two systems are in a state of exaggerated developmental plasticity early in postnatal life, and work in concert to respond to noxious or aversive stimuli. We present empirical evidence from animal and clinical studies, and discuss historical perspectives underlying the lack of analgesia/anesthetic use for early life pain in the modern NICU.

Sucrose and warmth for analgesia in healthy newborns: an RCT

BACKGROUND AND OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Continuous infusion versus intermittent bolus dosing of morphine: a comparison of analgesia, tolerance, and subsequent voluntary morphine intake

Improved utilization of continuous or intermittent opioid administration in pain treatment necessitates a comparison of the antinociceptive effect and tolerance of these two treatment methods. More importantly, the effect of treatment method on subsequent opioid consumption has not been directly compared, although it is widely assumed that continuous opioid treatment may produce lower addictive liability relative to intermittent opioid treatment. In this study, we compared the antinociceptive effect and tolerance of morphine in rats that received repeated injection (10 mg/kg twice daily for 7 days) or continuous infusion (20 mg/kg daily for 7 days) subcutaneously and the self-administration of intravenous morphine in these rats after 7 days of withdrawal. Both intermittent and continuous morphine treatment produced antinociceptive tolerance, but the exhibition of tolerance differed. Moreover, intermittent morphine pretreatment facilitated subsequent morphine self-administration, whereas continuous morphine pretreatment produced minimal effects, as shown by comparable levels of active responses and morphine consumption between continuous morphine and saline-treated rats. These results suggest that the administration method of opioid should be selected according to the specific pain situation and that continuous opioid administration or long-acting therapy may be advantageous, producing less influence on drug-taking behavior than intermittent administration of short-acting drugs.

Resuscitation volume in paediatric non-haemorrhagic blunt trauma

INTRODUCTION

Trauma is a major cause of paediatric morbidity and mortality, yet knowledge of fluid resuscitation is limited. Our objectives were to determine current practises in resuscitation volume (RV) administered to paediatric non-haemorrhagic (NH) blunt trauma patients and to identify fluid related complications.

METHODS

We examined data from 139 trauma patients 1-17 years of age with an injury severity score ≥ 12 resuscitated at a Trauma-designated Children's Hospital. Patients were separated into discreet groups based on ATLS age-dependent vital functions: toddler/preschooler (1-5 years), school age (6-12 years) and adolescent (13-17 years).

RESULTS

The median RV (total fluid intake-maintenance fluid intake) in ml/kg over the first 24h from the time of trauma by age was: 24 (IQR=19-47; 1-5 years); 26 (IQR=15-36; 6-12 years); and 22 (IQR=14-42; 13-17 years). The differences in RV/kg/24h following NH trauma was not significantly different between age groups (p=0.41). Urine output over the 24h ranged from 2.5 (IQR=1.9-3.3; lower age group) to 1.8 (IQR=1.2-2.4; upper age group) ml/kg/h; greater than the ATLS recommended age-dependent targets. Haematocrit was the only significant independent predictor of RV/kg/24h (p<0.001). Fluid-related complications attributable to RV were identified in 12% (n=17/139) of patients, and included ascites (8%; n=11/139) and/or pleural effusion(s) (9%; n=13/139). Patients with fluid-related complications received significantly more RV in ml/kg/24h (42, IQR=27-76) than those without complications (22, IQR=14-36; p=0.001).

CONCLUSIONS

The range of median RV administered to paediatric NH blunt trauma patients with ISS ≥ 12 was 22-26 ml/kg/24h. The RV administered was excessive based on high urine outputs and the presence of fluid-related complications. Further evaluation of RV triggers and endpoints used by paediatric traumatologists is required.

Pain and stress assessment after retinopathy of prematurity screening examination: indirect ophthalmoscopy versus digital retinal imaging

BACKGROUND

Increasingly, neonatal clinics seek to minimize painful experiences and stress for premature infants. Fundoscopy performed with a binocular indirect ophthalmoscope is the reference examination technique for screening of retinopathy of prematurity (ROP), and it is associated with pain and stress. Wide-field digital retinal imaging is a recent technique that should be evaluated for minimizing infant pain and stress.

METHODS

The purpose of the study was to assess and compare the impact of using a binocular indirect ophthalmoscope (BIO), or wide-field digital retinal imaging (WFDRI) on pain and stress in infants undergoing ROP screening examination. This was a comparative evaluation study of two screening procedures. Ophthalmologic examinations (N = 70) were performed on 24 infants with both BIO and WFDRI. Pain assessments were performed with two specific neonatal scales (Crying, requires oxygen, increased vital signs, expression and sleeplessness, CRIES and, Premature infant pain profile, PIPP) just prior to the examination, and 30 seconds, 1 hour, and 24 hours later after ending the examination.

RESULTS

Changes over time were significantly different between BIO and WFDRI with both scales (PIPP score, p = .007, and CRIES score, p = .001). Median PIPP score (interquartile interval) at baseline was 4 (3-5). At 30 seconds the score was 8 (6-9) for BIO and 6 (5-7) for WFDRI, respectively. The increase in PIPP score between baseline and 30 seconds was significantly lower with WFDRI (p = .006). The median increase in CRIES score from baseline to 30 seconds was 1 point lower for WFDRI than for BIO (p < .001). No significant difference in response remained at 1 hour or 24 hour assessments.

CONCLUSIONS

A transient short-term pain and stress response occurs with both BIO and WFDRI. Infants examined for screening of ROP with digital retinal imaging present less pain and stress at 30 seconds following completion of the exam when compared with binocular indirect ophthalmoscopy.

Circumcision of neonates and children without appropriate anaesthesia is unacceptable practice

Circumcision is painful surgery and appropriate intraoperative anaesthesia and postoperative analgesia is required. This is recognised in the policies of the Royal Australasian College of Physicians and the majority of Australian State Health Departments. Nevertheless, anecdotal evidence exists that neonatal circumcision continues to be performed in Australia with either no anaesthesia or with inadequate anaesthesia. This paper presents the evidence that neonatal circumcision is painful and reviews the available anaesthetic techniques. The authors conclude that general anaesthesia is arguably the most reliable way of ensuring adequate anaesthesia, although this may mean deferment of the procedure until the child is older. Local or regional anaesthesia for neonatal circumcision ideally requires a separate skilled anaesthetist (other than the proceduralist) to monitor the patient and intervene if the anaesthesia is inadequate. Topical anaesthesia with lignocaine-prilocaine (EMLA) cream is insufficient.

Pediatric analgesic clinical trial designs, measures, and extrapolation: report of an FDA scientific workshop

Analgesic trials pose unique scientific, ethical, and practical challenges in pediatrics. Participants in a scientific workshop sponsored by the US Food and Drug Administration developed consensus on aspects of pediatric analgesic clinical trial design. The standard parallel-placebo analgesic trial design commonly used for adults has ethical and practical difficulties in pediatrics, due to the likelihood of subjects experiencing pain for extended periods of time. Immediate-rescue designs using opioid-sparing, rather than pain scores, as a primary outcome measure have been successfully used in pediatric analgesic efficacy trials. These designs maintain some of the scientific benefits of blinding, with some ethical and practical advantages over traditional designs. Preferred outcome measures were recommended for each age group. Acute pain trials are feasible for children undergoing surgery. Pharmacodynamic responses to opioids, local anesthetics, acetaminophen, and nonsteroidal antiinflammatory drugs appear substantially mature by age 2 years. There is currently no clear evidence for analgesic efficacy of acetaminophen or nonsteroidal antiinflammatory drugs in neonates or infants younger than 3 months of age. Small sample designs, including cross-over trials and N of 1 trials, for particular pediatric chronic pain conditions and for studies of pain and irritability in pediatric palliative care should be considered. Pediatric analgesic trials can be improved by using innovative study designs and outcome measures specific for children. Multicenter consortia will help to facilitate adequately powered pediatric analgesic trials.

Baseline insulin/glucose ratio as a marker for the clinical course of hyperglycemic critically ill children treated with insulin

OBJECTIVE

The objective of this study was to investigate the relations of baseline insulin/glucose ratio to the clinical course of critically ill children. Such information will provide insight into the pathophysiologic mechanisms leading to hyperglycemia and will optimize preventive and therapeutic measures for hyperglycemia in critically ill children.

METHODS

Sixty-four consecutively admitted critically ill children with hyperglycemia, defined as a blood glucose level higher than 8 mmol/L (>145 mg/dL) and treated with insulin according to a glucose-control protocol, were included. Demographic data and clinical and laboratory parameters were collected. Insulin sensitivity was investigated by calculating the ratio of insulin to the blood glucose level just before the start of insulin administration. Results are expressed as median (range).

RESULTS

Sixty-four children (24 girls) 7.0 y of age (0.3-16.9 y) with various diagnoses were included. A hyperinsulinemic response, indicated by an increased insulin/glucose ratio (>18 pmol/mmol), was seen in 55% of children. The durations of insulin therapy, mechanical ventilation, and pediatric intensive care unit length of stay in children with a hyperinsulinemic response were longer than in children with a hypoinsulinemic response.

CONCLUSION

Hyper- and hypoinsulinemic responses play a role in the occurrence of hyperglycemia in critically ill children. Each is associated with a particular clinical course after the initiation of insulin therapy. It would be worthwhile to further investigate if the insulinemic response to hyperglycemia, determined by the insulin/glucose ratio in combination with the type of organ dysfunction, could be used in clinical practice to determine the need for insulin therapy.

Endpoints in pediatric pain studies

Assessing pain intensity in (preverbal) children is more difficult than in adults. Tools to measure pain are being used as primary endpoints [e.g., pain intensity, time to first (rescue) analgesia, total analgesic consumption, adverse effects, and long-term effects] in studies on the effects of analgesic drugs. Here, we review current and promising new endpoints used in pediatric pain assessment studies.

Disturbance of glucose homeostasis after pediatric cardiac surgery

This study aimed to evaluate the time course of perioperative blood glucose levels of children undergoing cardiac surgery for congenital heart disease in relation to endogenous stress hormones, inflammatory mediators, and exogenous factors such as caloric intake and glucocorticoid use. The study prospectively included 49 children undergoing cardiac surgery. Blood glucose levels, hormonal alterations, and inflammatory responses were investigated before and at the end of surgery, then 12 and 24 h afterward. In general, blood glucose levels were highest at the end of surgery. Hyperglycemia, defined as a glucose level higher than 8.3 mmol/l (>150 mg/dl) was present in 52% of the children at the end of surgery. Spontaneous normalization of blood glucose occurred in 94% of the children within 24 h. During surgery, glucocorticoids were administered to 65% of the children, and this was the main factor associated with hyperglycemia at the end of surgery (determined by univariate analysis of variance). Hyperglycemia disappeared spontaneously without insulin therapy after 12-24 h for the majority of the children. Postoperative morbidity was low in the study group, so the presumed positive effects of glucocorticoids seemed to outweigh the adverse effects of iatrogenic hyperglycemia.

Tolerance and withdrawal from prolonged opioid use in critically ill children

OBJECTIVE

After prolonged opioid exposure, children develop opioid-induced hyperalgesia, tolerance, and withdrawal. Strategies for prevention and management should be based on the mechanisms of opioid tolerance and withdrawal.

PATIENTS AND METHODS

Relevant manuscripts published in the English language were searched in Medline by using search terms "opioid," "opiate," "sedation," "analgesia," "child," "infant-newborn," "tolerance," "dependency," "withdrawal," "analgesic," "receptor," and "individual opioid drugs." Clinical and preclinical studies were reviewed for data synthesis.

RESULTS

Mechanisms of opioid-induced hyperalgesia and tolerance suggest important drug- and patient-related risk factors that lead to tolerance and withdrawal. Opioid tolerance occurs earlier in the younger age groups, develops commonly during critical illness, and results more frequently from prolonged intravenous infusions of short-acting opioids. Treatment options include slowly tapering opioid doses, switching to longer-acting opioids, or specifically treating the symptoms of opioid withdrawal. Novel therapies may also include blocking the mechanisms of opioid tolerance, which would enhance the safety and effectiveness of opioid analgesia.

CONCLUSIONS

Opioid tolerance and withdrawal occur frequently in critically ill children. Novel insights into opioid receptor physiology and cellular biochemical changes will inform scientific approaches for the use of opioid analgesia and the prevention of opioid tolerance and withdrawal.

Long-term impact of neonatal injury in male and female rats: Sex differences, mechanisms and clinical implications

Over the last several decades, the relative contribution of early life events to individual disease susceptibility has been explored extensively. Only fairly recently, however, has it become evident that abnormal or excessive nociceptive activity experienced during the perinatal period may permanently alter the normal development of the CNS and influence future responses to somatosensory input. Given the significant rise in the number of premature infants receiving high-technology intensive care over the last 20 years, ex-preterm neonates may be exceedingly vulnerable to the long-term effects of repeated invasive interventions. The present review summarizes available clinical and laboratory findings on the lasting impact of exposure to noxious stimulation during early development, with a focus on the structural and functional alterations in nociceptive circuits, and its sexually dimorphic impact.

Peri-operative hyperglycemia: a consideration for general surgery?

BACKGROUND

Intraoperative hyperglycemia in cardiac and neurosurgical patients is significantly associated with morbidity. Little is known about the perioperative glycemic profile or its impact in other surgical populations or in nondiabetic patients.

METHODS

A systematic review of blood glucose values during major general surgical procedures reported since 1980 was conducted. Data extracted included blood glucose measures, study sample size, gender distribution, age grouping, study purpose, surgical procedure, anesthetic details, and infusion regime. Excluded studies were those with subjects with diabetes insipidus, insulin-treated diabetes, renal or hepatic failure, adrenal gland tumors or dysfunction, pregnancy, and emergency or trauma surgery.

RESULTS

Blood glucose levels rose significantly with the induction of anesthesia (P < .001) in nondiabetic patients. At incision, 2 hours, 4 hours, and 6 hours, 30%, 40%, 38%, and 40% of studies, respectively, reported hyperglycemia.

CONCLUSIONS

Factors that confound or protect against significant rises in perioperative glycemic levels in nondiabetic patients were identified. The findings facilitate investigating the impact of hyperglycemia on general surgical outcomes.

Use of analgesic and sedative drugs in the NICU: integrating clinical trials and laboratory data

Recent advances in neonatal intensive care include and are partly attributable to growing attention for comfort and pain control in the term and preterm infant requiring intensive care.Limitation of painful procedures is certainly possible, but most critically ill infants require unavoidable painful or stressful procedures such as intubation, mechanical ventilation, or catheterization.Many analgesics (opioids and nonsteroidal anti-inflammatory drugs)and sedatives (benzodiazepines and other anesthetic agents) are available but their use varies considerably among units. This review summarizes current experimental knowledge on the effects of sedative and analgesic drugs on brain development and reviews clinical evidence that speaks for or against the use of common analgesic and sedative drugs in the NICU but avoids any discussion of anesthesia during surgery. Risk/benefit ratios of intermittent boluses or continuous infusions for the commonly used sedative and analgesic agents are discussed in the light of clinical and experimental studies. The limitations of extrapolating experimental results from animals to humans must be considered while making practical recommendations based on the currently available evidence.

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.

Skin conductance versus the modified COMFORT sedation score as a measure of discomfort in artificially ventilated children

OBJECTIVE

We wanted to use skin conductance as a measure of increased stress in artificially ventilated children. The aim was to examine how changes in skin conductance, arterial blood pressure, and heart rate are associated with changes in the modified COMFORT sedation score during suction from the trachea. Nociceptive stimulation induces an outgoing sympathetic nervous burst to the skin and the palmar and plantar sweat glands are filled, which creates a skin conductance fluctuation.

METHODS

Twenty children who were 1 day to 11 years of age were studied. All patients were artificially ventilated and circulatory stable. The data were obtained before, during, and 10 minutes after endotracheal suction. The number of skin conductance fluctuations, the amplitude of skin conductance fluctuations, the mean skin conductance level, arterial blood pressure, heart rate, and the modified COMFORT sedation score were recorded and tested from before to during and from during to after suction in the trachea. RESULTS. The number of skin conductance fluctuations, mean skin conductance level, arterial blood pressure, and the modified COMFORT sedation score increased during suction in the trachea, in contrast to heart rate and amplitude of skin conductance fluctuations. The number of skin conductance fluctuations from before to during and from during to after endotracheal suctioning correlated with changes in the modified COMFORT sedation score. This was in contrast to the other variables that did not.

CONCLUSIONS

The number of skin conductance fluctuations during endotracheal suctioning showed better correlation with the increase in the modified COMFORT sedation score than heart rate and arterial blood pressure. Thus, the number of skin conductance fluctuations seems to be an objective supplement to the modified COMFORT sedation score for monitoring increased stress in artificially ventilated and circulatory stable children.

Morphine pharmacokinetics and pharmacodynamics in preterm and term neonates: secondary results from the NEOPAIN trial

BACKGROUND

Relationships between plasma morphine concentrations and neonatal responses to endotracheal tube (ETT) suctioning are unknown in preterm neonates.

METHODS

Ventilated preterm neonates (n=898) from 16 centres were randomly assigned to placebo (n=449) or morphine (n=449). After an i.v. loading dose (100 microg kg(-1)), morphine infusions [23-26 weeks postmenstrual age (PMA) 10 microg kg(-1) h(-1); 27-29 weeks 20 microg kg(-1) h(-1); and 30-32 weeks 30 microg kg(-1) h(-1)] were established for a maximum of 14 days. Open-label morphine (20-100 microg kg(-1)) was given for pain or agitation. Morphine assay and neonatal response to ETT suctioning was measured at 20-28 and 70-76 h after starting the drug infusion and at 10-14 h after discontinuation of the study drug. The concentration-effect response was investigated using non-linear mixed effects models.

RESULTS

A total of 5119 data points (1598 measured morphine concentrations and 3521 effect measures) were available from 875 neonates for analysis. Clearance was 50% that of the mature value at 54.2 weeks PMA (CLmat(50)) and increased from 2.05 litre h(-1) 70 kg(-1) at 24 weeks PMA to 6.04 litre h(-1) 70 kg(-1) at 32 weeks PMA. The volume of distribution in preterm neonates was 190 litre 70 kg(-1) (CV 51%) and did not change with age. There was no relationship between morphine concentrations (range 0-440 microg litre(-1)) and heart rate changes associated with ETT suctioning or with the Premature Infant Pain Profile.

CONCLUSIONS

A sigmoid curve describing maturation of morphine clearance is moved to the right in preterm neonates and volume of distribution is increased compared with term neonates. Morphine does not alter the neonatal response to ETT suctioning.

Evidence-based assessment of pediatric pain

OBJECTIVE

To conduct an evidence-based review of pediatric pain measures.

METHODS

Seventeen measures were examined, spanning pain intensity self-report, questionnaires and diaries, and behavioral observations. Measures were classified as "Well-established," "Approaching well-established," or "Promising" according to established criteria. Information was highlighted to help professionals evaluate the instruments for particular purposes (e.g., research, clinical work).

RESULTS

Eleven measures met criteria for "Well-established," six "Approaching well-established," and zero were classified as "Promising."

CONCLUSIONS

There are a number of strong measures for assessing children's pain, which allows professionals options to meet their particular needs. Future directions in pain assessment are identified, such as highlighting culture and the impact of pain on functioning. This review examines the research and characteristics of some of the commonly used pain tools in hopes that the reader will be able to use this evidence-based approach and the information in future selection of assessment devices for pediatric pain.

Objective and continuous measurement of peripheral motor indicators of pain in hospitalized infants: a feasibility study

Measurement of pain in pre-verbal infants is complex. Until now, pain behavior has mainly been assessed intermittently using observational tools. Therefore, we determined the feasibility of long-term, objective and continuous measurement of peripheral motor parameters through body-fixed sensors to discriminate between pain and no pain in hospitalized pre-verbal infants. Two pain modes were studied: for procedural pain 10 measurements were performed before, during and after routine heel lances in 9 infants (age range infants: 5-175 days), and for post-operative pain 14 infants (age range 45-400 days) were measured for prolonged periods (mean 7h) using the validated COMFORT-behavior scale as reference method. Several peripheral motor parameters were studied: three body part activity parameters derived from acceleration sensors attached to one arm and both legs, and two muscle activity parameters derived from electromyographic (EMG) sensors attached to wrist flexor and extensor muscles. Results showed that the accelerometry-based parameters legs activity and overall extremity activity (i.e. mean of arm and legs) were significantly higher during heel lance than before or after lance (p0.001), whereas arm activity accelerometry data and wrist muscle activity EMG data showed no significant change. For the post-operative pain measurements, relationships were found between accelerometry-based overall extremity activity and COMFORT-behavior (r=0.76, p<0.001), and between EMG-based wrist flexor activity and COMFORT-behavior (r=0.55, p<0.001, for a subgroup of 7 infants). We conclude that long-term, objective and continuous measurement of peripheral motor parameters is feasible, has high potential, and is promising to assess pain in pre-verbal hospitalized infants.

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.

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.

Rectal acetaminophen does not reduce morphine consumption after major surgery in young infants

BACKGROUND

The safety and value of acetaminophen (paracetamol) in addition to continuous morphine infusion has never been studied in newborns and young infants. We investigated the addition of acetaminophen to evaluate whether it decreased morphine consumption in this age group after major thoracic (non-cardiac) or abdominal surgery.

METHODS

A randomized controlled trial was performed in 71 patients given either acetaminophen 90-100 mg kg(-1) day(-1)or placebo rectally, in addition to a morphine loading dose of 100 microg kg(-1) and 5-10 microg kg(-1) h(-1) continuous infusion. Analgesic efficacy was assessed using Visual Analogue Scale (VAS) and COMFORT scores. Extra morphine was administered if VAS was > or = 4.

RESULTS

We analysed data of 54 patients, of whom 29 received acetaminophen and 25 received placebo. Median (25-75th percentile) age was 0 (0-2) months. Additional morphine bolus requirements and increases in continuous morphine infusion were similar in both groups (P = 0.366 and P = 0.06, respectively). There was no significant difference in total morphine consumption, respectively, 7.91 (6.59-14.02) and 7.19 (5.45-12.06) mug kg(-1) h(-1) for the acetaminophen and placebo group (P = 0.60). COMFORT [median (25-75th percentile) acetaminophen 10 (9-12) and placebo 11 (9-13)] and VAS [median (25-75th percentile) acetaminophen 0.0 (0.0-0.2) and placebo 0.0 (0.0-0.3)] scores did not differ between acetaminophen and placebo group (P = 0.06 and P = 0.73, respectively).

CONCLUSIONS

Acetaminophen, as an adjuvant to continuous morphine infusion, does not have an additional analgesic effect and should not be considered as standard of care in young infants, 0-2 months of age, after major thoracic (non-cardiac) or abdominal surgery.

Potentially toxic effects of anaesthetics on the developing central nervous system

A growing body of experimental evidence suggests that anaesthetics, by influencing GABAergic and glutaminergic neural signalling, can have adverse effects on the developing central nervous system. The biological foundation for this is that gamma-aminobutyric acid and glutamate could act non-synaptically, in addition to their role in neurotransmission in the adult brain, in the regulation of neuronal development in the central nervous system. These neurotransmitters and their receptors are expressed from very early stages of central nervous system development and appear to influence neural progenitor proliferation, cell migration and neuronal differentiation. During the synaptogenetic period, pharmacological blockade of N-methyl-d-aspartate (NMDA)-type glutamate receptors as well as stimulation of GABAA receptors has been reported to be associated with increased apoptosis in the developing brain. Importantly, recent data suggest that even low, non-apoptogenic concentrations of anaesthetics can perturb neuronal dendritic development and thus could potentially lead to impairment of developing neuronal networks. The extrapolation of these experimental observations to clinical practice is of course very difficult and requires extreme caution as differences in drug concentrations and exposure times as well as interspecies variations are all important confounding variables. While clinicians should clearly not withhold anaesthesia based on current animal studies, these observations should urge more laboratory and clinical research to further elucidate this issue.

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.

Pain control: opioid dosing, population kinetics and side-effects

Neonates undergoing invasive procedures, postoperative pain or ventilatory support commonly receive opioids for treating pain and stress. Randomized clinical trials have examined the benefits and adverse effects of morphine or fentanyl for ventilated neonates and other indications. This paper summarizes the current evidence for opioid dosing in newborns, reviews their side-effects and explains the use of population kinetics and non-linear mixed-effects modeling to analyze the data from clinical trials. Opioid use should be reserved for severe pain postoperatively or during intensive care in neonates, using continuous infusions rather than intermittent boluses. The safety and efficacy data from prolonged opioid use, particularly on the long-term outcomes of neonates, is still lacking. The pharmacodynamics and pharmacogenetics of opioid use in infancy needs further investigation, using non-linear mixed-effects models to drive individualized therapy. The current interest in opioid research will reap rich dividends in providing pain relief for neonates and avoiding dangerous side effects.

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.

Analgesia and sedation during mechanical ventilation in neonates

BACKGROUND

Endotracheal intubation and mechanical ventilation are major components of routine intensive care for very low birth weight newborns and sick full-term newborns. These procedures are associated with physiologic, biochemical, and clinical responses indicating pain and stress in the newborn. Most neonates receive some form of analgesia and sedation during mechanical ventilation, although there are marked variations in clinical practice. Clinical guidelines for pharmacologic analgesia and sedation in newborns based on robust scientific data are lacking, as are measures of clinical efficacy.

OBJECTIVE

This article represents a preliminary attempt to develop a scientific rationale for analgesia sedation in mechanically ventilated newborns based on a systematic analysis of published clinical trials.

METHODS

The current literature was reviewed with regard to the use of opioids (fentanyl, morphine, diamorphine), sedative-hypnotics (midazolam), nonsteroidal anti-inflammatory drugs (ibuprofen, indomethacin), and acetaminophen in ventilated neonates. Original meta-analyses were conducted that collated the data from randomized clinical comparisons of morphine or fentanyl with placebo, or morphine with fentanyl.

RESULTS

The results of randomized trials comparing fentanyl, morphine, or midazolam with placebo, and fentanyl with morphine were inconclusive because of small sample sizes. Meta-analyses of the randomized controlled trials indicated that morphine and fentanyl can reduce behavioral and physiologic measures of pain and stress in mechanically ventilated preterm neonates but may prolong the duration of ventilation or produce other adverse effects. Randomized trials of midazolam compared with placebo reported significant adverse effects (P < 0.05) and no apparent clinical benefit; the findings of a meta-analysis suggest that there are insufficient data to justify use of IV midazolam for sedation in ventilated neonates.

CONCLUSIONS

Despite ongoing research in this area, huge gaps in our knowledge remain. Well-designed and adequately powered clinical trials are needed to establish the safety, efficacy, and short- and long-term outcomes of analgesia and sedation in the mechanically ventilated newborn.

Anesthesia and analgesia during and after surgery in neonates

BACKGROUND

Historically, the use of anesthetics and analgesics in neonates and infants has been based on extrapolations from studies performed in adults and older children. Over the past 20 years, there has been a growing body of research on the clinical pharmacology and clinical outcomes of these agents in neonates and infants.

OBJECTIVE

This article summarizes clinical pharmacology and clinical outcomes studies of opioids, opioid antagonists, sedative-hypnotics, nonsteroidal anti-inflammatory drugs and acetaminophen, and local anesthetics in neonates and infants to highlight gaps in the available knowledge, review some concerns about study design, and identify drugs that should receive high priority for future study.

METHODS

Relevant studies were identified through a search of MEDLINE and a review of textbooks, conference proceedings, and abstracts. The available literature was subjected to expert committee-based review.

CONCLUSIONS

There is a growing body of information on analgesic and anesthetic pharmacokinetics, pharmacodynamics, and clinical outcomes in neonates and infants, permitting safe and effective use in some clinical settings. Major gaps in knowledge persist, however. Future research may involve a combination of clinical trials and preclinical studies in suitable infant animal surrogate models.

Summary proceedings from the neonatal pain-control group

Recent advances in neurobiology and clinical medicine have established that the fetus and newborn may experience acute, established, and chronic pain. They respond to such noxious stimuli by a series of complex biochemical, physiologic, and behavioral alterations. Studies have concluded that controlling pain experience is beneficial with respect to short-term and perhaps long-term outcomes. Yet, pain-control measures are adopted infrequently because of unresolved scientific issues and lack of appreciation for the need for control of pain and its long-term sequelae during the critical phases of neurologic maturation in the preterm and term newborn. The neonatal pain-control group, as part of the Newborn Drug Development Initiative (NDDI) Workshop I, addressed these concerns. The specific issues addressed were (1) management of pain associated with invasive procedures, (2) provision of sedation and analgesia during mechanical ventilation, and (3) mitigation of pain and stress responses during and after surgery in the newborn infant. The cross-cutting themes addressed within each category included (1) clinical-trial designs, (2) drug prioritization, (3) ethical constraints, (4) gaps in our knowledge, and (5) future research needs. This article provides a summary of the discussions and deliberations. Full-length articles on procedural pain, sedation and analgesia for ventilated infants, perioperative pain, and study designs for neonatal pain research were published in Clinical Therapeutics (June 2005).

A systematic review of trial methodology, using the placebo groups of randomized controlled trials in paediatric postoperative pain

Trial methodology was evaluated in paediatric analgesic studies. Databases were searched for randomised, placebo controlled studies of systemic paracetamol, NSAIDs and opioids administered for acute postoperative pain in children. Eighty-three studies met the inclusion criteria and 40 were included for the analysis. Analgesics were administered for established postoperative pain in two studies only. In all other studies they were administered in a prophylactic manner. As study design and sensitivity are particularly demanding in studies using pre-emptive dosing of analgesics, the placebo groups were analysed for issues of study sensitivity. Postoperative pain outcomes included pain scores in 34, rescue analgesia in 36, time to first rescue analgesia in 15, pain on activity in eight, number of patients with pain in six, pain relief in three, global efficacy rating in two and analgesic consumption via PCA in four studies. Twenty of 36 studies reported criteria for rescue analgesia that varied from 20 to 77% of the maximum pain intensity. Need of rescue analgesia showed more often differences between study groups than time to first rescue analgesia or pain intensity. Rescue analgesia was administered to 21-100% of the patients in the placebo groups where no other analgesics were given perioperatively. Most patients in the placebo groups had pain that was greater than 30% of the maximum. In conclusion, analysis of the methodology showed several aspects of trial design that can be improved in future studies. Placebo control groups can be used in paediatric analgesic studies to demonstrate internal sensitivity.

Morphine does not provide adequate analgesia for acute procedural pain among preterm neonates

BACKGROUND

Morphine alleviates prolonged pain, reduces behavioral and hormonal stress responses induced by surgery among term neonates, and improves ventilator synchrony and sedation among ventilated preterm neonates, but its analgesic effects on the acute pain caused by invasive procedures remain unclear.

OBJECTIVE

To investigate the analgesic efficacy of intravenously administered morphine on heel stick-induced acute pain among preterm neonates.

DESIGN

This study was nested within a prospective, randomized, double-blind, multicenter, placebo-controlled trial (the NEOPAIN Trial).

SETTING

A tertiary-care NICU in a teaching hospital.

PARTICIPANTS

Forty-two preterm neonates undergoing ventilation.

INTERVENTIONS

Neonates were randomized to either the morphine (loading dose of 100 microg/kg, followed by infusions of 10-30 microg/kg per hour according to gestation, N = 21) or placebo (5% dextrose infusions, N = 21) group. Pain responses to 3 heel sticks were evaluated, ie, before the loading dose (T1), 2 to 3 hours after the loading dose (T2), and 20 to 28 hours after the loading dose (T3).

MAIN OUTCOMES MEASURES

Pain was assessed with the Douleur Aiguë Nouveau-né (DAN) scale (behavioral pain scale) and the Premature Infant Pain Profile (PIPP) (multidimensional pain scale); plasma morphine levels were measured at T3.

RESULTS

Infants in the placebo and morphine groups had similar gestational ages (mean +/- SD: 27.2 +/- 1.7 vs 27.3 +/- 1.8 weeks) and birth weights (972 +/- 270 vs 947 +/- 269 g). Mean +/- SD DAN pain scores at T1, T2, and T3 were 4.8 +/- 4.0, 4.6 +/- 2.9, and 4.7 +/- 3.6, respectively, for the placebo group and 4.5 +/- 3.8, 4.4 +/- 3.7, and 3.1 +/- 3.4 for the morphine group. The within-group factor (pain at T1, T2, and T3) was not statistically different over time. The between-group analysis (infants receiving placebo versus those receiving morphine) showed no significant differences. Mean +/- SD PIPP pain scores at T1, T2, and T3 were 11.5 +/- 4.8, 11.1 +/- 3.7, and 9.1 +/- 4.0, respectively, for the placebo group and 10.0 +/- 3.6, 8.8 +/- 4.9, and 7.8 +/- 3.6 for the morphine group. The within-group factor was statistically different over time. The between-group analysis showed no significant differences. Mean +/- SD plasma morphine levels at T3 were 0.44 +/- 1.79 ng/mL and 63.36 +/- 33.35 ng/mL for the placebo and morphine groups, respectively. There was no correlation between plasma morphine levels and pain scores at T3 (DAN, R = -0.05; PIPP, R = -0.02).

CONCLUSIONS

Despite its routine use in the NICU, morphine given as a loading dose followed by continuous intravenous infusions does not appear to provide adequate analgesia for the acute pain caused by invasive procedures among ventilated preterm neonates.

Adequate feeding and the usefulness of the respiratory quotient in critically ill children

OBJECTIVE

We determined incidences of underfeeding and overfeeding in children who were admitted to a multidisciplinary tertiary pediatric intensive care and evaluated the usefulness of the respiratory quotient (RQ) obtained from indirect calorimetry to assess feeding adequacy.

METHODS

Children 18 y and younger who fulfilled the criteria for indirect calorimetry entered our prospective, observational study and were studied until day 14. Actual energy intake was recorded, compared with required energy intake (measured energy expenditure plus 10%), and classified as underfeeding (<90% of required), adequate feeding (90% to 110% of required), or overfeeding (>110% of required). We also evaluated the adequacy of a measured RQ lower than 0.85 to identify underfeeding, and an RQ higher than 1.0 to identify overfeeding.

RESULTS

Ninety-eight children underwent 195 calorimetric measurements. Underfeeding, adequate feeding, and overfeeding occurred on 21%, 10%, and 69% of days, respectively. An RQ lower than 0.85 to identify underfeeding showed low sensitivity (63%), high specificity (89%), and high negative predictive value (90%). An RQ higher than 1.0 to indicate overfeeding showed poor sensitivity (21%), but a high specificity (97%) and a high positive predictive value (93%). Food composition, notably high-carbohydrate intake, was responsible for an RQ exceeding 1.0 in the overfed group.

CONCLUSION

Children admitted to the intensive care unit receive adequate feeding on only 10% of measurement days during the first 2 wk of admission. The usefulness of RQ to monitor feeding adequacy is limited to identifying (carbohydrate) overfeeding and excluding underfeeding.