Tolerance and withdrawal from prolonged opioid use in critically ill children

Consequences of prenatal opioid use for newborns

One-third of childbearing women take prescription opioids, previously occurring only in 6-7% of pregnant women. Prenatal opioid exposures may cause birth defects, altered brain development and neonatal abstinence syndrome (NAS). NAS incidence increased fourfold and length of stay increased from 13 to 19 days over 10 years (2004-2013), leading to sevenfold increases in NICU days due to NAS. Initial data suggest that recent NAS increases have resulted from increased use of prescription opioids rather than illicit drugs.

CONCLUSION

Paediatricians will have to manage the consequences of prenatal opioid exposures, as the offspring often have complex medical and social issues associated with these families.

Long-term behavioral effects in a rat model of prolonged postnatal morphine exposure

Prolonged morphine treatment in neonatal pediatric populations is associated with a high incidence of opioid tolerance and dependence. Despite the clinical relevance of this problem, our knowledge of long-term consequences is sparse. The main objective of this study was to investigate whether prolonged morphine administration in a neonatal rat is associated with long-term behavioral changes in adulthood. Newborn animals received either morphine (10 mg/kg) or equal volume of saline subcutaneously twice daily for the first 2 weeks of life. Morphine-treated animals underwent 10 days of morphine weaning to reduce the potential for observable physical signs of withdrawal. Animals were subjected to nonstressful testing (locomotor activity recording and a novel-object recognition test) at a young age (Postnatal Days [PDs] 27-31) or later in adulthood (PDs 55-56), as well as stressful testing (calibrated forceps test, hot plate test, and forced swim test) only in adulthood. Analysis revealed that prolonged neonatal morphine exposure resulted in decreased thermal but not mechanical threshold. Importantly, no differences were found for total locomotor activity (proxy of drug reward/reinforcement behavior), individual forced swim test behaviors (proxy of affective processing), or novel-object recognition test. Performance on the novel-object recognition test was compromised in the morphine-treated group at the young age, but the effect disappeared in adulthood. These novel results provide insight into the long-term consequences of opioid treatment during an early developmental period and suggest long-term neuroplastic differences in sensory processing related to thermal stimuli.

Optimizing Sedation Management to Promote Early Mobilization for Critically Ill Children

Achieving successful early mobilization for the intubated, critically ill child is dependent on optimizing sedation and analgesia. Finding the fine balance between oversedation and undersedation can be challenging. The ideal is for a child to be lucid and interactive during the daytime and demonstrate normal circadian rhythm for sleep with rest at night. Being alert during the day facilitates active participation in therapy including potential ambulation, while decreasing the risk of delirium during mechanical ventilation. An active state during the day with frequent mobilization promotes restorative sleep at night, which brings with it multiple benefits for healing and recovery. Indeed, this ideal may not be physiologically feasible given a child's critical illness and trajectory, but defining it as the "gold standard" for early mobilization provides a consistent goal for the pediatric intensive care unit (PICU) hospitalization. As such, goal-directed, patient-specific sedation plans are integral to creating a culture of mobility in the PICU. We review currently available sedation strategies for mechanically ventilated children for successful implementation of early mobilization in the PICU, as well as pharmacologic considerations for specific classes of sedative-analgesics.

Pediatric Withdrawal Identification and Management

Sedation administered by continuous intravenous infusion is commonly used in the pediatric intensive care unit to facilitate and maintain safe care of children during critical illness. Prolonged use of sedatives, including opioids, benzodiazepines, and potentially other adjunctive agents, is known to cause withdrawal symptoms when they are stopped abruptly or weaned quickly. In this review, the common signs and symptoms of opioid, benzodiazepine, and dexmedetomidine withdrawal will be discussed. Current tools used to measure withdrawal objectively, as well as withdrawal prevention and management strategies, will be discussed.

Nonpulmonary treatments for pediatric acute respiratory distress syndrome: proceedings from the Pediatric Acute Lung Injury Consensus Conference

OBJECTIVE

To describe the recommendations from the Pediatric Acute Lung Injury Consensus Conference on nonpulmonary treatments in pediatric acute respiratory distress syndrome.

DESIGN

Consensus conference of experts in pediatric acute lung injury.

METHODS

A panel of 27 experts met over the course of 2 years to develop a taxonomy to define pediatric acute respiratory distress syndrome and to make recommendations regarding treatment and research priorities. The nonpulmonary subgroup comprised three experts. When published data were lacking, a modified Delphi approach emphasizing strong professional agreement was utilized.

RESULTS

The Pediatric Acute Lung Injury Consensus Conference experts developed and voted on a total of 151 recommendations addressing the topics related to pediatric acute respiratory distress syndrome, 30 of which related to nonpulmonary treatment. All 30 recommendations had strong agreement. Patients with pediatric acute respiratory distress syndrome should receive 1) minimal yet effective targeted sedation to facilitate mechanical ventilation; 2) neuromuscular blockade, if sedation alone is inadequate to achieve effective mechanical ventilation; 3) a nutrition plan to facilitate their recovery, maintain their growth, and meet their metabolic needs; 4) goal-directed fluid management to maintain adequate intravascular volume, end-organ perfusion, and optimal delivery of oxygen; and 5) goal-directed RBC transfusion to maintain adequate oxygen delivery. Future clinical trials in pediatric acute respiratory distress syndrome should report sedation, neuromuscular blockade, nutrition, fluid management, and transfusion exposures to allow comparison across studies.

CONCLUSIONS

The Consensus Conference developed pediatric-specific definitions for pediatric acute respiratory distress syndrome and recommendations regarding treatment and future research priorities. These recommendations for nonpulmonary treatment in pediatric acute respiratory distress syndrome are intended to promote optimization and consistency of care for patients with pediatric acute respiratory distress syndrome and identify areas of uncertainty requiring further investigation.

Effects of Clonidine on Withdrawal From Long-term Dexmedetomidine in the Pediatric Patient

OBJECTIVE

To compare withdrawal symptoms among pediatric intensive care patients receiving clonidine to those not receiving clonidine while being weaned from long-term dexmedetomidine.

METHODS

This retrospective analysis evaluated Withdrawal Assessment Tool-1 (WAT-1) scores and hemodynamic parameters in pediatric patients on dexmedetomidine for 5 days or longer between January 1, 2009, and December 31, 2012. The primary objective was to compare withdrawal symptoms based on the number of elevated WAT-1 scores among patients on clonidine to those not on clonidine, while being weaned from long-term dexmedetomidine. The secondary objective was to describe withdrawal symptoms associated with long-term dexmedetomidine use.

RESULTS

Nineteen patients (median age, 1.5 years; interquartile range [IQR], 0.67-3.3) received 20 treatment courses of dexmedetomidine for at least 5 days. Clonidine was received by patients during 12 of the treatment courses. The patients in the clonidine group had an average of 0.8 (range, 0-6) elevated WAT-1 scores 24 hours post wean compared to an average of 3.2 (0-8) elevated WAT-1 scores in the no clonidine group (p = 0.49). There were no significant difierences between prewean and postwean systolic or diastolic blood pressures among the 2 groups. The average heart rate during the postwean period was 112 beats per minute (bpm) (range, 88.5-151.5) in the clonidine group compared to 138.4 bpm (range, 117.8-168.3) in the no clonidine group (p = 0.003). In the clonidine group, the mean change in heart rate postwean compared to prewean was an increase of 3.6 bpm (range, -39.6 to 47.5), compared to a mean increase of 29.9 bpm (range, 5.5-74.7) in the no clonidine group (p = 0.042).

CONCLUSIONS

There was no difierence in WAT-1 scores between groups, with the clonidine group displaying a trend towards fewer elevated WAT-1 scores during the 24 hours post dexmedetomidine wean. Patients who received clonidine had significantly lower heart rates than the no clonidine group.

Sedation and analgesia in the ICU

The alleviation of pain and anxiety is an important component of caring for a critically ill child. Sedation and analgesia regimens are utilized as adjuncts to procedures, facilitate mechanical ventilation, and assist with management of a critically ill child. Although sedation regimens have been used extensively across intensive care units, the data are lacking as to the best drugs, dosing, regimens, and short- and long-term safety profiles for use in the pediatric population. Sedation regimens continue to be a challenging aspect of the care of a critically ill child, and they have been associated with significant morbidity in this population. This article will discuss the sedative use in the intensive care unit, morbidity associated with sedatives and analgesics, and the importance of establishing sedation and analgesia algorithms to reduce morbidity and mortality.

Risk factors associated with iatrogenic opioid and benzodiazepine withdrawal in critically ill pediatric patients: a systematic review and conceptual model

OBJECTIVES

Analgesia and sedation are common therapies in pediatric critical care, and rapid titration of these medications is associated with iatrogenic withdrawal syndrome. We performed a systematic review of the literature to identify all common and salient risk factors associated with iatrogenic withdrawal syndrome and build a conceptual model of iatrogenic withdrawal syndrome risk in critically ill pediatric patients.

DATA SOURCES

Multiple databases, including PubMed/Medline, EMBASE, CINAHL, and the Cochrane Central Registry of Clinical Trials, were searched using relevant terms from January 1, 1980, to August 1, 2014.

STUDY SELECTION

Articles were included if they were published in English and discussed iatrogenic withdrawal syndrome following either opioid or benzodiazepine therapy in children in acute or intensive care settings. Articles were excluded if subjects were neonates born to opioid- or benzodiazepine-dependent mothers, children diagnosed as substance abusers, or subjects with cancer-related pain; if data about opioid or benzodiazepine treatment were not specified; or if primary data were not reported.

DATA EXTRACTION

In total, 1,395 articles were evaluated, 33 of which met the inclusion criteria. To facilitate analysis, all opioid and/or benzodiazepine doses were converted to morphine or midazolam equivalents, respectively. A table of evidence was developed for qualitative analysis of common themes, providing a framework for the construction of a conceptual model. The strongest risk factors associated with iatrogenic withdrawal syndrome include duration of therapy and cumulative dose. Additionally, evidence exists linking patient, process, and system factors in the development of iatrogenic withdrawal syndrome.

FINDINGS

Most articles were prospective observational or interventional studies.

CONCLUSIONS

Given the state of existing evidence, well-designed prospective studies are required to better characterize iatrogenic withdrawal syndrome in critically ill pediatric patients. This review provides data to support the construction of a conceptual model of iatrogenic withdrawal syndrome risk that, if supported, could be useful in guiding future research.

Protocolized sedation vs usual care in pediatric patients mechanically ventilated for acute respiratory failure: a randomized clinical trial

IMPORTANCE

Protocolized sedation improves clinical outcomes in critically ill adults, but its effect in children is unknown.

OBJECTIVE

To determine whether critically ill children managed with a nurse-implemented, goal-directed sedation protocol experience fewer days of mechanical ventilation than patients receiving usual care.

DESIGN, SETTING, AND PARTICIPANTS

Cluster randomized trial conducted in 31 US pediatric intensive care units (PICUs). A total of 2449 children (mean age, 4.7 years; range, 2 weeks to 17 years) mechanically ventilated for acute respiratory failure were enrolled in 2009-2013 and followed up until 72 hours after opioids were discontinued, 28 days, or hospital discharge.

INTERVENTION

Intervention PICUs (17 sites; n = 1225 patients) used a protocol that included targeted sedation, arousal assessments, extubation readiness testing, sedation adjustment every 8 hours, and sedation weaning. Control PICUs (14 sites; n = 1224 patients) managed sedation per usual care.

MAIN OUTCOMES AND MEASURES

The primary outcome was duration of mechanical ventilation. Secondary outcomes included time to recovery from acute respiratory failure, duration of weaning from mechanical ventilation, neurological testing, PICU and hospital lengths of stay, in-hospital mortality, sedation-related adverse events, measures of sedative exposure (wakefulness, pain, and agitation), and occurrence of iatrogenic withdrawal.

RESULTS

Duration of mechanical ventilation was not different between the 2 groups (intervention: median, 6.5 [IQR, 4.1-11.2] days; control: median, 6.5 [IQR, 3.7-12.1] days). Sedation-related adverse events including inadequate pain and sedation management, clinically significant iatrogenic withdrawal, and unplanned endotracheal tube/invasive line removal were not significantly different between the 2 groups. Intervention patients experienced more postextubation stridor (7% vs 4%; P = .03) and fewer stage 2 or worse immobility-related pressure ulcers (<1% vs 2%; P = .001). In exploratory analyses, intervention patients had fewer days of opioid administration (median, 9 [IQR, 5-15] days vs 10 [IQR, 4-21] days; P = .01), were exposed to fewer sedative classes (median, 2 [IQR, 2-3] classes vs 3 [IQR, 2-4] classes; P < .001), and were more often awake and calm while intubated (median, 86% [IQR, 67%-100%] of days vs 75% [IQR, 50%-100%] of days; P = .004) than control patients, respectively; however, intervention patients had more days with any report of a pain score ≥ 4 (median, 50% [IQR, 27%-67%] of days vs 23% [IQR, 0%-46%] of days; P < .001) and any report of agitation (median, 60% [IQR, 33%-80%] vs 40% [IQR, 13%-67%]; P = .003), respectively.

CONCLUSIONS AND RELEVANCE

Among children undergoing mechanical ventilation for acute respiratory failure, the use of a sedation protocol compared with usual care did not reduce the duration of mechanical ventilation. Exploratory analyses of secondary outcomes suggest a complex relationship among wakefulness, pain, and agitation.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00814099.

Systemwide change of sedation wean protocol following pediatric laryngotracheal reconstruction

IMPORTANCE

Pediatric laryngotracheal reconstruction (LTR) remains the standard surgical technique for expanding a stenotic airway and necessitates a multidisciplinary team. Sedation wean following LTR is a critical component of perioperative care. We identified variation and communications deficiencies with our sedation wean practice and describe our experience implementing a standardized sedation wean protocol.

OBJECTIVE

To standardize and decrease length of sedation wean in pediatric patients undergoing LTR.

DESIGN, SETTING, AND PARTICIPANTS

Using Institute for Healthcare Improvement (IHI) methodology, we implemented systemwide change at a tertiary care center with the goal of improving care based on best practice guidelines. We created a standardized electronic sedation wean communication document and retrospectively examined our experience in 29 consecutive patients who underwent LTR before (n = 16, prewean group) and after (n = 13, postwean group) wean document implementation.

INTERVENTIONS

Implementation of a standardized sedation protocol.

MAIN OUTCOMES AND MEASURES

Presence of sedation wean document in the electronic medical record, length of sedation wean, and need for continued wean after discharge.

RESULTS

The sedation wean document was used in 92.3% patients in the postwean group. With the new process, the mean (SD) length of sedation wean was reduced from 16.19 (11.56) days in the prewean group to 8.92 (3.37) days in the postwean group (P = .045). Fewer patients in the postwean group required continued wean after discharge (81.3% vs 33.3%; P = .02).

CONCLUSIONS AND RELEVANCE

We implemented a systemwide process change with the goal of improving care based on best practice guidelines, which significantly decreased the time required for sedation wean following LTR. Our methodological approach may have implications for other heterogeneous patient populations requiring a sedation wean.

Pain management in newborns

As a standard of care for preterm/term newborns effective pain management may improve their clinical and neurodevelopmental outcomes. Neonatal pain is assessed using context-specific, validated, and objective pain methods, despite the limitations of currently available tools. Therapeutic approaches reducing invasive procedures and using pharmacologic, behavioral, or environmental measures are used to manage neonatal pain. Nonpharmacologic approaches like kangaroo care, facilitated tucking, non-nutritive sucking, sucrose, and others can be used for procedural pain or adjunctive therapy. Local/topical anesthetics, opioids, NSAIDs/acetaminophen and other sedative/anesthetic agents can be incorporated into NICU protocols for managing moderate/severe pain or distress in all newborns.

Variation of opioid use in pediatric inpatients across hospitals in the U.S

CONTEXT

Appropriate use of opioids is essential to manage moderate-to-severe pain in children safely and effectively, yet published guidance regarding opioid treatment for pediatric patients is limited, potentially resulting in excessive variation in opioid use in pediatric patients across hospitals in the U.S.

OBJECTIVES

The aim was to evaluate hospital variation in opioid use in pediatric inpatients.

METHODS

Using data from the Pediatric Health Information System and the Premier Perspective Database regarding all pediatric inpatients in 626 hospitals, we examined hospital variation in opioid use and the length of opioid use, adjusting for patient demographic and clinical characteristics and for hospital type (children's vs. general) and hospital patient volume, using multilevel generalized linear regression modeling.

RESULTS

Overall, 41.2% of all pediatric hospitalizations were exposed to opioids. Among the exposed patients, the mean length of exposure was 4.6 days. Exposure proportion and exposure length varied substantially across hospitals, even after accounting for patient demographic and clinical characteristics, hospital type and hospital patient volume, especially among terminal hospitalizations. For patients discharged alive vs. died, the adjusted exposure percentage for each hospital ranged from 0.7% to 99.1% (interquartile range [IQR]: 35.3%-59.9%) vs. 0.1% to 100.0% (IQR: 29.2%-66.2%), respectively, and the adjusted exposure length ranged from 1.0 to 8.4 days (IQR: 2.2-2.7 days) vs. 0.9 to 35.2 days (IQR: 4.0-7.4 days).

CONCLUSION

The substantial hospital-level variation in opioid use in pediatric inpatients suggests room for improvement in clinical practice.

Pain Management for Children during Bone Marrow and Stem Cell Transplantation

Pain management for children during bone marrow and stem cell transplantation is a significant clinical challenge for the health care team. Pain management strategies vary by institution. This paper reports on the use of a pediatric pain management service and patient- and caregiver-controlled analgesia for children undergoing transplant. This 2-year retrospective chart review examined the pain management practices and outcomes of children undergoing bone marrow and stem cell transplants in a large urban teaching hospital during 2008 and 2009. We concluded that patient- and caregiver-controlled analgesia is a well-tolerated modality for pain control during hospitalization for transplantation at this institution.

Ketamine PCA for treatment of end-of-life neuropathic pain in pediatrics

Control of neuropathic pain (NP) for children at end of life is challenging. Ketamine improves control of NP, but its use in children is not well described. We describe a retrospective case review of 14 children with terminal prognoses treated with ketamine patient-controlled analgesia (PCA) for management of opioid-refractory NP at the end of life. Median ketamine dose was 0.06 mg/kg/h (range 0.014-0.308 mg/kg/h) with a 0.05 mg/kg (range 0.03-0.5mg/kg) demand dose available every 15 minutes (range 10-60 minutes). All patients noted subjective pain relief with ketamine, and 79% had no adverse effects. Benzodiazepines limited neuropsychiatric side effects. Ketamine treatment arrested dose escalation of opioids in 64% of patients, and 79% were discharged to home hospice. Ketamine PCA is an effective, well-tolerated therapy for opioid-refractory NP in pediatric end-of-life care.

Continuous infusion of clonidine in ventilated newborns and infants: a randomized controlled trial

OBJECTIVES

To assess the influence of an infusion of clonidine 1 μg/kg/hr on fentanyl and midazolam requirement in ventilated newborns and infants.

DESIGN

Prospective, double-blind, randomized controlled multicenter trial. Controlled trials.com/ISRCTN77772144.

SETTING

Twenty-eight level 3 German PICUs/neonatal ICUs.

PATIENTS

Ventilated newborns and infants: stratum I (1-28 d), stratum II, (29-120 d), and stratum III (121 d to 2 yr).

INTERVENTIONS

Patients received clonidine 1 μg/kg/hr or placebo on day 4 after intubation. Fentanyl and midazolam were adjusted to achieve a defined level of analgesia and sedation according to Hartwig score.

MEASUREMENTS AND MAIN RESULTS

Two hundred nineteen infants were randomized; 212 received study medication, 69.7% were ventilated in the postoperative care and 30.3% for other reasons. Primary endpoint: consumption of fentanyl and midazolam in the 72 hours following the onset of study medication (main observation period) in the overall study population. The confirmatory analysis of the overall population showed no difference in the consumption of fentanyl and midazolam. Explorative age-stratified analysis demonstrated that in stratum I (n = 112) the clonidine group had a significantly lower consumption of fentanyl (clonidine: 2.1 ± 1.8 μg/kg/hr, placebo: 3.2 ± 3.1 μg/kg/hr; p = 0.032) and midazolam (clonidine: 113.0 ± 100.1 μg/kg/hr, placebo: 180.2 ± 204.0 μg/kg/hr; p = 0.030). Strata II (n = 43) and III (n = 46) showed no statistical difference. Sedation and withdrawal-scores were significantly lower in the clonidine group of stratum I (p < 0.001). Frequency of severe adverse events did not differ between groups.

CONCLUSIONS

Clonidine 1 μg/kg/hr in ventilated newborns reduced fentanyl and midazolam demand with deeper levels of analgesia and sedation without substantial side effects. This was not demonstrated in older infants, possibly due to lower clonidine serum levels.

Strategies for preventing side effects of systemic opioid in postoperative pediatric patients

BACKGROUND AND OBJECTIVES

Opioid is the gold standard for treating moderate-to-severe pain in pediatric patients. However, its undesirable side effects lead to unsatisfied postoperative pain management outcome (Pediatr Anesth, 17, 2007, 756). The most commonly reported opioid-related side effects are vomiting (40%), pruritus (20-60%) (Anesthesiology, 77, 1992, 162; Drugs, 67, 2007, 2323), and constipation (15-90%) (Int J Clin Pract, 61, 2007, 1181). The potential life-threatening adverse event, respiratory depression, is less common (0.0013%) (Pediatr Anesth, 20, 2010, 119). The aim of this review was to evaluate prevention strategies that have been shown to decrease opioid side effects in pediatric patients during the postoperative period.

METHODS

Literature searches were conducted from 1984 to February 2013. Meta-analysis, systematic review, and randomized, placebo-controlled studies were obtained from PubMed and the Cochrane Library. The medical subject heading (MeSH) terms were opioid analgesics, adverse effects, pediatrics, children, side effects, and postoperative pain.

RESULTS AND CONCLUSION

Data from 62 studies were reviewed. The strategies that could effectively prevent and reduce opioid side effects in pediatric patients during the postoperative period included minimizing the amount of opioid consumption by a multimodal approach, opioid titration, using local anesthetic techniques and providing the specific prophylaxis for each side effect.

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.

Perioperative epidural analgesia in children undergoing major abdominal tumor surgery--a single center experience

PURPOSE

The purpose of this study was to assess the use of continuous epidural analgesia in pediatric patients undergoing major abdominal tumor surgery.

METHODS

Children undergoing major abdominal tumor surgery at our institution between 2008 and 2012 (n=40) received continuous epidural analgesia via an epidural catheter. Surgical trauma scores, pain scores, and clinical data of the children were compared to a pair-matched historical control group operated on between 2002 and 2007 without epidural analgesia.

RESULTS

Pain levels in the study group on day 1 and 3 after surgery were lower compared to the control group. The differences did, however, not reach statistical significance (p=0.15 and 0.09). Children in the study group received significantly fewer additional doses of piritramide or morphine (45% versus 82%, p<0.001). Despite significantly higher surgical trauma scores in the study group (p=0.018), there were no statistical differences regarding clinical parameters, such as mechanical ventilation time, time on intensive care unit, and total hospital stay. There were no catheter-related complications.

CONCLUSIONS

Continuous epidural analgesia is beneficial for children undergoing complex abdominal tumor surgery with regard to pain levels, postoperative recovery, and general clinical course. Expertise of the managing team, a careful patient selection, and a continuous quality assessment are essential for success.

Effects of repeated dosing with mechanistically distinct antinociceptive ligands in a rat model of neuropathic spinal cord injury pain

A lack of efficacy of some analgesic drugs has been previously described in rats with neuropathic spinal cord injury (SCI) pain. It has been suggested that repeated dosing in these animals over time may eventually lead to efficacy. However, it is also possible that efficacy may diminish over time with repeated dosing. This study evaluated the efficacy of various drugs upon repeated dosing over time in a rat model of SCI pain. Four weeks following an acute spinal cord compression at the mid-thoracic level, rats developed decreased hind paw withdrawal threshold, suggestive of below level neuropathic hypersensitivity. Either cannabinoid (CB) receptor agonist CP 55,940, the anticonvulsant carbamazepine or gabapentin, the antidepressant amitriptyline or vehicle was administered over a period of 7 days. Neither carbamazepine nor amitriptyline demonstrated efficacy either after a single or repeated dosing. Beginning with a 50% efficacious dose of gabapentin, the effect of gabapentin in SCI rats neither increased nor decreased over the treatment period. The antinociceptive effect of CP 55,940 was maintained for the entire treatment period, which was mediated by CB1 but not CB2 receptors. The current data suggest that sustained antinociception can be obtained with some drugs in rats with neuropathic SCI pain. Furthermore, the current data do not substantiate the notion that repeated treatment with initially ineffective drugs will eventually lead to efficacy; treatments that are not acutely effective are unlikely to demonstrate clinical efficacy.

Evaluation of a pharmacist-managed methadone taper*

OBJECTIVES

To evaluate the efficacy of a pharmacist-managed methadone taper as compared to previous prescribing practices.

DESIGN

Retrospective chart review with comparison to historical controls.

SETTING

Ninety-six-bed pediatric quaternary care facility with the majority of the patients in a 24-bed ICU.

PATIENTS

Thirty-two patients, 1 month to 16 years old, weaned off opioids using methadone prior to protocol initiation were compared with 20 patients, 1 month to 15 years old, weaned per the pharmacist-managed methadone taper protocol.

INTERVENTIONS

Implementation of a pharmacist-managed methadone tapering protocol.

MEASUREMENTS AND MAIN RESULTS

Patient age, gender, weight, and risk of withdrawal were similar between the groups (p = not significant). The average taper length before pharmacist intervention was 24.7 days; after implementation it was 15 days (p = 0.0026). There was no statistical difference in the number of additional doses of opioid required or withdrawal scores between the populations. Opioid infusions were stopped, on average, 1.54 days sooner in the intervention group (p = 0.0039). A decrease in hospital length of stay was also seen in the intervention group (p = 0.023).

CONCLUSIONS

A pharmacist-managed protocolized methadone taper facilitates discontinuing methadone sooner, discontinuing additional opioid infusions sooner, and may impact on the length of hospital stay. The protocol developed at the University of Minnesota Amplatz Children's Hospital has demonstrated that it is an effective method to wean pediatric patients from opioids.

Neonatal pain

Effective management of procedural and postoperative pain in neonates is required to minimize acute physiological and behavioral distress and may also improve acute and long-term outcomes. Painful stimuli activate nociceptive pathways, from the periphery to the cortex, in neonates and behavioral responses form the basis for validated pain assessment tools. However, there is an increasing awareness of the need to not only reduce acute behavioral responses to pain in neonates, but also to protect the developing nervous system from persistent sensitization of pain pathways and potential damaging effects of altered neural activity on central nervous system development. Analgesic requirements are influenced by age-related changes in both pharmacokinetic and pharmacodynamic response, and increasing data are available to guide safe and effective dosing with opioids and paracetamol. Regional analgesic techniques provide effective perioperative analgesia, but higher complication rates in neonates emphasize the importance of monitoring and choice of the most appropriate drug and dose. There have been significant improvements in the understanding and management of neonatal pain, but additional research evidence will further reduce the need to extrapolate data from older age groups. Translation into improved clinical care will continue to depend on an integrated approach to implementation that encompasses assessment and titration against individual response, education and training, and audit and feedback.

Recognition and management of iatrogenically induced opioid dependence and withdrawal in children

Opioids are often prescribed to children for pain relief related to procedures, acute injuries, and chronic conditions. Round-the-clock dosing of opioids can produce opioid dependence within 5 days. According to a 2001 Consensus Paper from the American Academy of Pain Medicine, American Pain Society, and American Society of Addiction Medicine, dependence is defined as "a state of adaptation that is manifested by a drug class specific withdrawal syndrome that can be produced by abrupt cessation, rapid dose reduction, decreasing blood level of the drug, and/or administration of an antagonist." Although the experience of many children undergoing iatrogenically induced withdrawal may be mild or goes unreported, there is currently no guidance for recognition or management of withdrawal for this population. Guidance on this subject is available only for adults and primarily for adults with substance use disorders. The guideline will summarize existing literature and provide readers with information currently not available in any single source specific for this vulnerable pediatric population.

Sedation and analgesia in critically ill children

The interplay of pain, discomfort, and fear can cause agitation in critically ill children. Therefore, sedation and analgesia are essential components in the intensive care unit setting and are best managed with a multidisciplinary team approach. No one standard approach exists to assess and manage pain and anxiety. Many tools are available for the assessment of pain and sedation, but each tool has its advantages and disadvantages. Clinicians should consider adopting a validated tool for routine continuous assessment. Multiple pharmacological therapies are available to manage pain, anxiety, fear, and agitation. Dosing of these agents can be influenced by age-related pharmacokinetic and pharmacodynamic changes. Agents should be selected on the basis of the child's disease state, desired level of sedation, and cardiac and respiratory status.

External Validation of the Medication Taper Complexity Score for Methadone Tapers in Children With Opioid Abstinence Syndrome

Background: Methadone is commonly prescribed for children with opioid abstinence syndrome (OAS) as a taper schedule over several days to weeks. The Medication Taper Complexity Score (MTCS) was developed to evaluate outpatient methadone tapers. Objective: To further validate the MTCS and determine if it is a reliable tool for clinicians to use to assess the complexity of methadone tapers for OAS. Methods: An expert panel of pediatric clinical pharmacists was convened. Panel members were provided 9 methadone tapers (ie, “easy,” “medium,” and “difficult”) to determine construct and face validity of the MTCS. The primary objective was to further establish reliability and construct/face validity of the MTCS. The secondary objective was to assess the reliability of the MTCS within and between tapers. Instrument reliability was assessed using a Pearson correlation coefficient; with 0.8 as the minimum acceptable coefficient. Construct (divergent) validity was assessed via a repeated-measures ANOVA analysis (Bonferroni post hoc analyses) of the mean scores provided by panel members. Results: Six panel members were recruited from various geographical locations. Panel members had 18.3 ± 5.5 years of experience, with practice expertise in general pediatrics, hematology/oncology, and the pediatric and neonatal intensive care unit. The MTCS had a reliability coefficient of .9949. There was vivid discrimination between the easy, medium, and difficult tapers; P = .001. The panel recommended minor modifications to the MTCS. Conclusions: The MTCS was found to be a reliable and valid tool. Overall, the panel felt that the MTCS was easy to use and had potential applications in both practice and research.

Psychometric evaluation of the Sophia Observation withdrawal symptoms scale in critically ill children

OBJECTIVE

The Sophia Observation withdrawal Symptoms scale is an instrument for screening benzodiazepine and opioid withdrawal syndrome in pediatric critical care patients. The objectives of this study were to establish cutoff scores and to test sensitivity to change. Second, risk factors for withdrawal syndrome were explored.

DESIGN

Prospective observational study with repeated measures.

SETTING

Level IV ICU at a university children's hospital.

PATIENTS

A total of 154 children with median age 5 months (interquartile range, 0-42 mo) who received continuous infusion of benzodiazepines and/or opioids for 5 or more days.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Nurses repeatedly applied the Sophia Observation withdrawal Symptoms scale and the Numeric Rating Scale withdrawal when children were weaned off benzodiazepines and opioids. The latter represents the nurse's expert opinion. We analyzed 3,754 paired assessments; the median number per child was 15 (interquartile range, 7-31) over a median of 5 days (interquartile range, 3-11 d). Sensitivity and specificity were 0.83 and 0.93, respectively, for the Sophia Observation withdrawal Symptoms scale cutoff score of 4 or higher against a Numeric Rating Scale-withdrawal score of 4 or higher. Sensitivity to change was determined by comparing 156 Sophia Observation withdrawal Symptoms scale assessments (n = 51 patients) before and after additional sedatives or opioids. Multilevel regression analysis showed a mean decline of 1.5 points (at score range 0-15) after intervention (p < 0.0001). Logistic regression analysis identified duration of preweaning of midazolam, duration of weaning of midazolam, duration of preweaning of morphine, duration of weaning of morphine, and number of additional sedatives/opioids as statistically significant risk factors for withdrawal syndrome in these children.

CONCLUSIONS

The Sophia Observation withdrawal Symptoms scale is a valid tool with good psychometric properties to assess withdrawal symptoms in PICU patients.

Opioid withdrawal signs and symptoms in children: frequency and determinants

OBJECTIVES

The purpose of this study was to, in a pediatric population, describe the frequency of opioid withdrawal signs and symptoms and to identify factors associated with these opioid withdrawal signs and symptoms.

BACKGROUND

Opioids are used routinely in the pediatric intensive care population for analgesia, sedation, blunting of physiologic responses to stress, and safety. In children, physical dependence may occur in as little as 2-3 days of continuous opioid therapy. Once the child no longer needs the opioid, the medications are reduced over time.

METHODS

A prospective, descriptive study was conducted. The sample of 26 was drawn from all patients, ages 2 weeks to 21 years admitted to the Children's Hospital of Richmond pediatric intensive care unit (PICU) and who have received continuous infusion or scheduled opioids for at least 5 days. Data collected included: opioid withdrawal score (WAT-1), opioid taper rate (total dose of opioid per day in morphine equivalents per kilogram [MEK]), pretaper peak MEK, pretaper cumulative MEK, number of days of opioid exposure prior to taper, and age.

RESULTS

Out of 26 enrolled participants, only 9 (45%) had opioid withdrawal on any given day. In addition, there was limited variability in WAT-1 scores. The most common symptoms notes were diarrhea, vomit, sweat, and fever.

CONCLUSIONS

For optimal opioid withdrawal assessments, clinicians should use a validated instrument such as the WAT-1 to measure for signs and symptoms of opioid withdrawal. Further research is indicated to examine risk factors for opioid withdrawal in children.

Regional anesthesia in neonates and infants

Optimal pain management can significantly impact the surgical outcome and length of stay in the neonatal intensive care unit (NICU). Regional anesthesia is an effective alternative that can be used in both term and preterm neonates. A variety of neuraxial and peripheral nerve blocks have been used for specific surgical and NICU procedures. Ultrasound guidance has increased the feasibility of using these techniques in neonates. Education and training staff in the use of continuous epidural infusions are important prerequisites for successful implementation of regional anesthesia in NICU management protocols.

Efficacy and safety of continuous infusion of fentanyl for pain control in preterm newborns on mechanical ventilation

OBJECTIVE

To evaluate the analgesic superiority and the safety equivalence of continuous fentanyl infusions versus fentanyl boluses in preterm infants on mechanical ventilation.

STUDY DESIGN

In this multicenter, double-blind, randomized controlled trial, mechanically ventilated newborns (≤ 32(+6) weeks gestational age) were randomized to fentanyl (continuous infusion of fentanyl plus open-label boluses of fentanyl) or placebo (continuous infusion of placebo plus open-label boluses of fentanyl). The primary endpoint was analgesic efficacy, as evaluated by the Echelle Douleur Inconfort Nouveau-Né (EDIN) and Premature Infant Pain Profile scales. Safety variables were evaluated as well.

RESULTS

Sixty-four infants were allocated to the fentanyl group, and 67 were allocated to the placebo group. The need for open-label boluses of fentanyl was similar in the 2 groups (P = .949). EDIN scores were comparable in the 2 groups; 65 of 961 (6.8%) EDIN scores were >6 in the fentanyl group and 91 of 857 (10.6%) in the placebo group (P = .003). The median Premature Infant Pain Profile score was clinically and statistically higher in the placebo group compared with the fentanyl group on days 1, 2, and 3 of treatment (P < .05). Mechanical ventilation at age 1 week was required in 27 of 64 infants in the fentanyl group (42.2%), compared with 17 of 67 infants in the placebo group (25.4%) (P = .042). The first cycle of mechanical ventilation was longer and the first meconium passage occurred later in the fentanyl group (P = .019 and .027, respectively).

CONCLUSION

In very preterm infants on mechanical ventilation, continuous fentanyl infusion plus open-label boluses of fentanyl does not reduce prolonged pain, but does reduce acute pain and increase side effects compared with open-label boluses of fentanyl alone.

Babies breaking bad: neonatal and iatrogenic withdrawal syndromes

PURPOSE OF REVIEW

This review will summarize the symptoms, evaluation, and treatment of neonatal and iatrogenic withdrawal syndromes.

RECENT FINDINGS

Buprenorphine is emerging as the drug of choice for maintaining opioid-dependent women during pregnancy, because of its association with less severe withdrawal symptoms. Recent findings suggest it may be the drug of choice for treating the opioid-exposed neonate as well.

SUMMARY

Healthcare workers should be cognizant of the risk factors for neonatal abstinence syndrome (NAS), as well as its symptoms, so that nonpharmalogic and pharmacologic therapies can be initiated. With increased emphasis on pain control in children, it is likely that iatrogenic withdrawal will continue to be a concern, and healthcare workers should understand the similarities and differences between this and NAS.

Morphine-enhanced apoptosis in selective brain regions of neonatal rats

Prolonged neonatal opioid exposure has been associated with: antinociceptive tolerance, long-term neurodevelopmental delay, cognitive, and motor impairment. Morphine has also been shown to induce apoptotic cell death in vitro studies, but its in vivo effect in developing rat brain is unknown. Thus, we hypothesized that prolongued morphine administration in neonatal rats in a model of antinociceptive tolerance and dependence is associated with increased neuroapoptosis. We analyzed neonatal rats from the following groups (1) naïve group (n=6); (2) control group (normal saline (NS), n=5), and (3) morphine group (n=8). Morphine sulfate or equal volume of NS was injected subcutaneously twice daily for 6½ days starting on postnatal day (PD) 1. Development of antinociceptive tolerance was previously confirmed by Hot Plate test on the 7th day. Evidence of neuronal and glial apoptosis was determined by cleaved caspase-3 immunofluorescence combined with specific markers. At PD7, morphine administration after 6½ days significantly increased the density of apoptotic cells in the cortex and amygdala, but not in the hippocampus, hypothalamus, or periaqueductal gray. Apoptotic cells exhibited morphology analogous to neurons. Irrespective of the treatment, only a very few individual microglia but not astrocytes were caspase-3 positive. In summary, repeated morphine administration in neonatal rats (PD1-7) is associated with increased supraspinal apoptosis in distinct anatomical regions known to be important for sensory (cortex) and emotional memory processing (amygdala). Brain regions important for learning (hippocampus), and autonomic and nociceptive processing (hypothalamus and periaqueductal gray) were not affected. Lack of widespread glial apoptosis or robust glial activation following repeated morphine administration suggests that glia might not be affected by chronic morphine at this early age. Future studies should investigate long-term behavioral sequelae of demonstrated enhanced apoptosis associated with prolonged morphine administration in a neonatal rat model.

Opioid analgesia in mechanically ventilated children: results from the multicenter Measuring Opioid Tolerance Induced by Fentanyl study

OBJECTIVE

To examine the clinical factors associated with increased opioid dose among mechanically ventilated children in the pediatric intensive care unit.

DESIGN

Prospective, observational study with 100% accrual of eligible patients.

SETTING

Seven pediatric intensive care units from tertiary-care children's hospitals in the Collaborative Pediatric Critical Care Research Network.

PATIENTS

Four hundred nineteen children treated with morphine or fentanyl infusions.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Data on opioid use, concomitant therapy, demographic and explanatory variables were collected. Significant variability occurred in clinical practices, with up to 100-fold differences in baseline opioid doses, average daily or total doses, or peak infusion rates. Opioid exposure for 7 or 14 days required doubling of the daily opioid dose in 16% patients (95% confidence interval 12%-19%) and 20% patients (95% confidence interval 16%-24%), respectively. Among patients receiving opioids for longer than 3 days (n = 225), this occurred in 28% (95% confidence interval 22%-33%) and 35% (95% confidence interval 29%-41%) by 7 or 14 days, respectively. Doubling of the opioid dose was more likely to occur following opioid infusions for 7 days or longer (odds ratio 7.9, 95% confidence interval 4.3-14.3; p < 0.001) or co-therapy with midazolam (odds ratio 5.6, 95% confidence interval 2.4-12.9; p < 0.001), and it was less likely to occur if morphine was used as the primary opioid (vs. fentanyl) (odds ratio 0.48, 95% confidence interval 0.25-0.92; p = 0.03), for patients receiving higher initial doses (odds ratio 0.96, 95% confidence interval 0.95-0.98; p < 0.001), or if patients had prior pediatric intensive care unit admissions (odds ratio 0.37, 95% confidence interval 0.15-0.89; p = 0.03).

CONCLUSIONS

Mechanically ventilated children require increasing opioid doses, often associated with prolonged opioid exposure or the need for additional sedation. Efforts to reduce prolonged opioid exposure and clinical practice variation may prevent the complications of opioid therapy.

Remifentanil-induced tolerance, withdrawal or hyperalgesia in infants: a randomized controlled trial. RAPIP trial: remifentanil-based analgesia and sedation of paediatric intensive care patients

BACKGROUND

Short-acting opioids like remifentanil are suspected of an increased risk for tolerance, withdrawal and opioid-induced hyperalgesia (OIH). These potential adverse effects have never been investigated in neonates.

OBJECTIVES

To compare remifentanil and fentanyl concerning the incidence of tolerance, withdrawal and OIH.

METHODS

23 mechanically ventilated infants received up to 96 h either a remifentanil- or fentanyl-based analgesia and sedation regimen with low-dose midazolam. We compared the required opioid doses and the number of opioid dose adjustments. Following extubation, withdrawal symptoms were assessed by a modification of the Finnegan score. OIH was evaluated by the CHIPPS scale and by testing the threshold of the flexion withdrawal reflex with calibrated von Frey filaments.

RESULTS

Remifentanil had to be increased by 24% and fentanyl by 47% to keep the infants adequately sedated during mechanical ventilation. Following extubation, infants revealed no pronounced opioid withdrawal and low average Finnegan scores in both groups. Only 1 infant of the fentanyl group and 1 infant of the remifentanil group required methadone for treatment of withdrawal symptoms. Infants also revealed no signs of OIH and low CHIPPS scores in both groups. The median threshold of the flexion withdrawal reflex was 4.5 g (IQR = 2.3) in the fentanyl group and 2.7 g (IQR = 3.3) in the remifentanil group (p = 0.312), which is within the physiologic range of healthy infants.

CONCLUSIONS

Remifentanil does not seem to be associated with an increased risk for tolerance, withdrawal or OIH.

Periaqueductal gray neuroplasticity following chronic morphine varies with age: role of oxidative stress

The development of tolerance to the antinociceptive effects of morphine has been associated with networks within ventrolateral periaqueductal gray (vlPAG) and separately, nitric oxide signaling. Furthermore, it is known that the mechanisms that underlie tolerance differ with age. In this study, we used a rat model of antinociceptive tolerance to morphine at two ages, postnatal day (PD) 7 and adult, to determine if changes in the vlPAG related to nitric oxide signaling produced by chronic morphine exposure were age-dependent. Three pharmacological groups were analyzed: control, acute morphine, and chronic morphine group. Either morphine (10mg/kg) or equal volume of normal saline was given subcutaneously twice daily for 6½ days. Animals were analyzed for morphine dose-response using Hot Plate test. The expression of several genes associated with nitric oxide metabolism was evaluated using rtPCR. In addition, the effect of morphine exposure on immunohistochemistry for Fos, and nNOS as well as nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) reaction at the vlPAG were measured. In both age groups acute morphine activated Fos in the vlPAG, and this effect was attenuated by chronic morphine, specifically in the vlPAG at the level of the laterodorsal tegmental nucleus (LDTg). In adults, but not PD7 rats, chronic morphine administration was associated with activation of nitric oxide function. In contrast, changes in the gene expression of PD7 rats suggested superoxide and peroxide metabolisms may be engaged. These data indicate that there is supraspinal neuroplasticity following morphine administration as early as PD7. Furthermore, oxidative stress pathways associated with chronic morphine exposure appear age-specific.

Infant pupillary response to methadone administration during treatment for neonatal abstinence syndrome: a feasibility study

BACKGROUND

Pupil diameter is a frequently assessed objective index of the pharmacodynamic effects of opioids in adults, but to our knowledge has never been examined in infants. Such a measure could improve assessment and treatment of neonates exposed to opioids in utero. The present study examined changes in pupil diameter after opioid administration in opioid-exposed infants who required pharmacological treatment for neonatal abstinence syndrome (NAS) to test the feasibility of using pupil diameter as a measure of opioid effects in these infants.

METHODS

Ten infants (2-7 days old) receiving methadone (0.4-0.5 mg every 12 h) for the treatment of NAS participated. A picture of one of each infant's eyes was taken under controlled illumination conditions with a standard digital camera just prior to dosing and 0-1, 2-4, 5-7, and 8-10h after dosing. The diameters of the pupil and iris were measured and relative pupil diameter (pupil diameter expressed as a percentage of iris diameter) was analyzed.

RESULTS

Mean (±SE) relative pupil diameter decreased significantly after dosing from 41±2% to 29±2%. After dosing, a significant increasing linear trend was observed over time, with values of 29±2%, 33±3%, 38±3%, and 41±3% at 0-1, 2-4, 5-7, and 8-10h after dosing.

CONCLUSIONS

Infant pupils respond to opioid administration in the same sensitive, orderly manner as is commonly observed in adults. Pupil diameter appears to be an objective, sensitive measure of neonatal response to opioids that may be a useful complement to, or perhaps at times a replacement for, observer-rated scale scores.

Biomarkers and clinical tools in critically ill children: are we heading toward tailored drug therapy?

In pediatric critical care, validated biomarkers are essential for guiding drug therapy. The aim of this article is to present examples of current biomarker developments in its full breadth, including biochemical substances, physiological measurements and clinical scoring tools, with a focus on the field of circulatory, renal and neurophysiologic failure. Within each field we consecutively discuss the rationale for the selected biomarkers, studies in critically ill children, biomarker validation stage and biomarker use or potential use in drug studies and clinical drug dosing. This article demonstrates that there is paucity of properly validated biomarkers. Nevertheless, recent developments in, for instance, the field of sepsis, point us toward a future wherein, for critically ill children, drug therapy may be personalized using proteomic profiling instead of a small number of biomarkers, in order to establish a personal and dynamic disease profile.

Pharmacologic management of the opioid neonatal abstinence syndrome

Opioid use in pregnant women has increased over the last decade. Following birth, infants with in utero exposure demonstrate signs and symptoms of withdrawal known as the neonatal abstinence syndrome (NAS). Infants express a spectrum of disease, with most requiring the administration of pharmacologic therapy to ensure proper growth and development. Treatment often involves prolonged hospitalization. There is a general lack of high-quality clinical trial data to guide optimal therapy, and significant heterogeneity in treatment approaches. Emerging trends in the treatment of infants with NAS include the use of sublingual buprenorphine, transition to outpatient therapy, and pharmacogenetic risk stratification.

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.

Selection of the initial methadone regimen for the management of iatrogenic opioid abstinence syndrome in critically ill children

Iatrogenic opioid abstinence syndrome (IOAS) is a common complication in critically ill infants and children receiving prolonged exposure to continuous infusions of opioids. Although no guidelines are available regarding management of IOAS in children, several treatment options are available, including clonidine, morphine, and methadone. Methadone is commonly prescribed due to its long half-life and antagonism of the N-methyl-d-aspartate receptor. Different approaches, such as weight-based and formula-based methods, have been used to determine the initial methadone dosing regimen. Because of the vast differences in the recommended dosing regimen from these sources, we conducted a literature search to identify articles evaluating the initial methadone dosing regimen for prevention and/or treatment of IOAS in children. Specifically, we evaluated the reported frequency of withdrawal and oversedation after initiation of methadone treatment. Our literature search was limited to English-language articles in the MEDLINE (1950-March 2011), EMBASE (1988-March 2011), International Pharmaceutical Abstracts (1970-March 2011), and Cochrane Library (1996-March 2011) databases. Relevant abstracts and reference citations were also reviewed. A total of eight reports representing 183 patients were included in the analysis. There was wide discrepancy in the initial methadone dosing regimen. Approximately one-third of all patients experienced withdrawal after starting methadone, and there did not appear to be a difference between weight-based and formula-based regimens. Seven patients experienced oversedation; however, not all articles reported this complication. It appears that a standard approach to initial methadone dosing does not exist because withdrawal occurred despite the regimen started. Therefore, it seems best to begin with the lowest dose possible and titrate to the child's response to avoid complications such as oversedation. Routine monitoring should be performed in all patients to guide clinicians in the management of IOAS.

A pilot study assessing the frequency and complexity of methadone tapers for opioid abstinence syndrome in children discharged to home

BACKGROUND

Methadone is often prescribed as a taper schedule to prevent/treat opioid abstinence syndrome (OAS) or neonatal abstinence syndrome (NAS).

OBJECTIVE

The objective of this study was to determine the percentage of children discharged home on methadone tapers and to develop, assess, and implement an instrument for measuring the complexity of the methadone regimens.

METHODS

This study used a descriptive retrospective design to examine patients younger than 18 years from January 1, 2008, to December 31, 2008, administered methadone for prevention/treatment of OAS/NAS and discharged home on a methadone taper. Data collection included demographics and characteristics of methadone regimen. The primary objective was to determine the percentage of children discharged on methadone. Secondary objectives included characterization (ie, number of dosage and interval changes), duration, and complexity of the methadone taper. Descriptive statistics were performed using Stata v10 (StataCorp LP, College Station, TX). Complexity was evaluated using the medication taper complexity score (MTCS) between 4 raters. Reliability of the MTCS was established using interrater correlation analyses of the regimen complexity scores.

RESULTS

Thirty-three patients (41.8%) were discharged on methadone. The median (range) age was 0.42 (0-12) years, with most patients (75.8%) initiated on methadone for prevention of OAS. Thirty-one patients were included for further analysis of medication complexity. The median (range) duration of the home taper was 8 days (2-48), which included a median (range) of 4 (1-11) dose changes and at least 1 (0-2) change in the interval. MTCS ranged from 7 to 42, with the tool demonstrating 95% interrater reliability.

CONCLUSIONS

More than one-third of patients were discharged home on methadone. The median taper duration was 8 days and included a median of 5 adjustments in either the dose or interval. The MTCS demonstrated very good interrater reliability to measure wide variability in the complexity of individual tapers. Future studies should determine the construct validity of the MTCS and the applicability of this tool for further research and clinical application.

Endogenous opiates and behavior: 2010

This paper is the thirty-third consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2010 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration (Section 16); and immunological responses (Section 17).

Pro con debate: the use of regional vs systemic analgesia for neonatal surgery

In recent years the inclusion of regional techniques to pediatric anesthesia has transformed practice. Simple procedures such as caudal anesthesia with local anaesthetics can reduce the amounts of general anesthesia required and provide complete analgesia in the postoperative period while avoiding large amounts of opioid analgesia with potential side effects that can impair recovery. However, the application of central blocks (epidural and spinal local anesthesia) via catheters in the younger infant, neonate and even preterm neonate remains more controversial. The potential for such invasive maneuvers themselves to augment risk, can be argued to outweigh the benefits, others would argue that epidural analgesia can reduce the need for postoperative ventilation and that this not only facilitates surgery when intensive care facilities are limited, but also reduces cost in terms of PICU stay and recovery profile. Currently, opinions are divided and strongly held with some major units adopting this approach widely and others maintaining a more conservative stance to anesthesia for major neonatal surgery. In this pro-con debate the evidence base is examined, supplemented with expert opinion to try to provide a balanced overall view.

Validity and generalizability of the Withdrawal Assessment Tool-1 (WAT-1) for monitoring iatrogenic withdrawal syndrome in pediatric patients

Critically ill pediatric patients frequently receive prolonged analgesia and sedation to provide pain relief and facilitate intensive care therapies. Iatrogenic withdrawal syndrome occurs when these drugs are stopped abruptly or weaned too rapidly. We investigated the validity and generalizability of the Withdrawal Assessment Tool-1 (WAT-1) in children during weaning of analgesics and sedatives. Of 308 children initially supported on mechanical ventilation for acute respiratory failure, 126 (41%) from 21 centers (median age 1.6 years; interquartile range 0.6-7.7 years) were exposed to 5 or more days of opioids. Subjects were assessed for withdrawal symptoms with the WAT-1, an 11-item (12-point) scale, from the first day of weaning from analgesia/sedation until 72 h after the last opioid dose. A total of 836 daily WAT-1 assessments were completed, with a median (interquartile range) WAT-1 score of 2 (0-4) over 6 (3-9) days per subject. There were no significant differences in WAT-1 scores as a function of age. Factor analyses confirmed that motor-related symptoms and behavioral state accounted for the most variance in WAT-1 scores. Supporting construct validity, cumulative opioid exposures were greater [40.2 (19.7-83.4) vs 17.6 (14.6-39.7) mg/kg, P=.004], length of opioid treatment before weaning was longer [7 (6-11) vs 5 (5-8)days, P=.004], and length of weaning from opioids was longer [10 (6-14) vs 6 (3-9)days, P=.008] in subjects with WAT-1 scores of ≥ 3 compared to subjects with WAT-1 scores of <3. The WAT-1 shows good psychometric performance and generalizability when used to assess clinically important withdrawal symptoms in pediatric intensive care and general ward settings.

Quantitative analysis of rate and extent of tolerance of biomarkers: application to nicotinic acid-induced changes in non-esterified fatty acids in rats

In this paper we quantitatively evaluate two feedback systems with a focus on rate and extent of tolerance and rebound development. In the two feedback systems, the regulation of turnover of response is governed by one or several moderators. In the basic system, one single moderator inhibits the formation of response. This system has been applied to cortisol secretion and serotonin reuptake inhibition. The basic system has been extended to adequately describe nicotinic acid (NiAc)-induced changes in non-esterified fatty acids (NEFA). In the extended system, the feedback is described by a cascade of moderators where the first inhibits formation of response and the last stimulates loss of response. The objectives of this paper were to analyze these systems from a mathematical/analytical and quantitative point of view and to present simulations with different parameter settings and dosing regimens in order to highlight the intrinsic behaviour of these systems and to present expressions and graphs that are applicable for quantification of rate and extent of tolerance and rebound. The dynamics of the moderators (k(tol)) compared to the dynamics of the response (k(out)), was shown to be important for the behaviour of both systems. For instance, slow dynamics of the moderator compared to the response (k(tol)<<k(out)), resulted in overshoot and pronounced rebound. The extent of tolerance was studied over time at a single constant drug concentration and at steady state for different drug concentrations and was found to be largest at drug concentrations close to IC(50). An upper limit for the response could be identified and included in the quantification of extent of rebound. Especially, for the extended system, the duration of exposure was an important factor affecting size of rebound. The rate of tolerance development was addressed by quantitatively estimating the time to steady state for the two systems, in which the value of k(tol) and the length of the cascade were critical.