Prospective study on the occurrence of withdrawal in critically ill children who receive fentanyl by continuous infusion

Defining sedation-related adverse events in the pediatric intensive care unit

BACKGROUND

Clinical trials exploring optimal sedation management in critically ill pediatric patients are urgently needed to improve both short- and long-term outcomes. Concise operational definitions that define and provide best-available estimates of sedation-related adverse events (AE) in the pediatric population are fundamental to this line of inquiry.

OBJECTIVES

To perform a multiphase systematic review of the literature to identify, define, and provide estimates of sedation-related AEs in the pediatric ICU setting for use in a multicenter clinical trial.

METHODS

In Phase One, we identified and operationally defined the AE. OVID-MEDLINE and CINAHL databases were searched from January 1998 to January 2012. Key terms included sedation, intensive and critical care. We limited our search to data-based clinical trials from neonatal to adult age. In Phase Two, we replicated the search strategy for all AEs and identified pediatric-specific AE rates.

RESULTS

We reviewed 20 articles identifying sedation-related adverse events and 64 articles on the pediatric-specific sedation-related AE. A total of eleven sedation-related AEs were identified, operationally defined and estimated pediatric event rates were derived. AEs included: inadequate sedation management, inadequate pain management, clinically significant iatrogenic withdrawal, unplanned endotracheal tube extubation, post-extubation stridor with chest-wall retractions at rest, extubation failure, unplanned removal of invasive tubes, ventilator-associated pneumonia, catheter-associated bloodstream infection, Stage II+ pressure ulcers and new tracheostomy.

CONCLUSIONS

Concise operational definitions that defined and provided best-available event rates of sedation-related AEs in the pediatric population are presented. Uniform reporting of adverse events will improve subject and patient safety.

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.

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.

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.

Replacement of fentanyl infusion by enteral methadone decreases the weaning time from mechanical ventilation: a randomized controlled trial

INTRODUCTION

Patients undergoing mechanical ventilation (MV) are frequently administered prolonged and/or high doses of opioids which when removed can cause a withdrawal syndrome and difficulty in weaning from MV. We tested the hypothesis that the introduction of enteral methadone during weaning from sedation and analgesia in critically ill adult patients on MV would decrease the weaning time from MV.

METHODS

A double-blind randomized controlled trial was conducted in the adult intensive care units (ICUs) of four general hospitals in Brazil. The 75 patients, who met the criteria for weaning from MV and had been using fentanyl for more than five consecutive days, were randomized to the methadone (MG) or control group (CG). Within the first 24 hours after study enrollment, both groups received 80% of the original dose of fentanyl, the MG received enteral methadone and the CG received an enteral placebo. After the first 24 hours, the MG received an intravenous (IV) saline solution (placebo), while the CG received IV fentanyl. For both groups, the IV solution was reduced by 20% every 24 hours. The groups were compared by evaluating the MV weaning time and the duration of MV, as well as the ICU stay and the hospital stay.

RESULTS

Of the 75 patients randomized, seven were excluded and 68 were analyzed: 37 from the MG and 31 from the CG. There was a higher probability of early extubation in the MG, but the difference was not significant (hazard ratio: 1.52 (95% confidence interval (CI) 0.87 to 2.64; P = 0.11). The probability of successful weaning by the fifth day was significantly higher in the MG (hazard ratio: 2.64 (95% CI: 1.22 to 5.69; P < 0.02). Among the 54 patients who were successfully weaned (29 from the MG and 25 from the CG), the MV weaning time was significantly lower in the MG (hazard ratio: 2.06; 95% CI 1.17 to 3.63; P < 0.004).

CONCLUSIONS

The introduction of enteral methadone during weaning from sedation and analgesia in mechanically ventilated patients resulted in a decrease in the weaning time from MV.

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.

Dexmedetomidine for opioid and benzodiazepine withdrawal in pediatric patients

PURPOSE

The published literature on the use of dexmedetomidine as an adjunct to sedation and analgesia in the management of pediatric narcotic withdrawal was reviewed.

SUMMARY

Pediatric narcotic withdrawal syndromes are reported to be increasingly frequent in pediatric intensive care units. A number of tools specifically designed for assessment of withdrawal in newborns and infants are in current use, including the widely used Finnegan Scoring System. A limited number of studies and case reports suggest that dexmedetomidine, an α(2)-receptor agonist with a mechanism of action similar to that of clonidine but with greater α(2)-receptor specificity, might have a role in the treatment of pediatric withdrawal (by blunting withdrawal symptoms without causing respiratory depression and by permitting shorter narcotic tapering schedules) and also in the prevention of pediatric narcotic withdrawal (by reducing narcotic requirements). Potential adverse effects associated with dexmedetomidine use in pediatric patients are generally associated with use of bolus doses and mainly involve central nervous system effects (e.g., hypotension, bradycardia), with no hemodynamic manifestations. When bolus doses are used, strategies described in published reports entail a loading dose of 0.5-1.0 μg/kg administered over 5-10 minutes, followed by a continuous infusion at 0.1-1.4 μg/kg/hr for a period of 1-16 days. More research is needed to define the optimal use of dexmedetomidine in the management of pediatric narcotic withdrawal.

CONCLUSION

A limited body of published evidence from retrospective studies and case reports suggests a potential role for dexmedetomidine as an adjunct therapy to provide sedation and analgesia to reduce narcotic withdrawal symptoms in pediatric patients.

Perioperative opiate requirements in children with previous opiate infusion

BACKGROUND

Critically ill children often require continuous opiate infusions. Tolerance may develop requiring a weaning strategy to prevent withdrawal symptoms. These children may also require subsequent surgical procedures. This is the first study to investigate whether previously opiate-tolerant patients require higher doses of opiates for adequate pain management perioperatively.

METHODS

A retrospective study was conducted at a tertiary children's hospital to investigate whether children previously exposed to continuous opiates for 10 or more days with subsequent weaning from those opiates will have similar or increased perioperative opiate requirements when compared to opioid-naïve controls. Study patients included 31 children with previous continuous opiate exposure for 10 or more days followed by weaning and without signs of withdrawal for at least 72 h prior to the surgical procedure. Excluded were patients over 18 years of age, those whose surgical procedures would be unlikely to require perioperative opiates, oncological patients, burn patients, neurologically devastated patients, and patients who received regional anesthesia in addition to perioperative narcotics. The control group consisted of 31 age- and case-matched opiate-naïve patients who underwent a surgical procedure during a similar time frame as the study patient. The medication administration record was reviewed for the length of continuous opiate exposure, date of last opiate use prior to a subsequent surgical procedure, and opiate use during the perioperative period. Opiate use was calculated as morphine equivalents per kilogram body weight (MSEQ·kg(-1)). The Wilcoxon rank sum test was used for univariate comparisons between matched pairs, and P-values <0.05 were considered statistically significant.

RESULTS

The perioperative opiate requirements in opiate-exposed patients (median, interquartile range: 0.14, 0.08-0.25 MSEQ·kg(-1)) were not significantly different from opiate-naïve patients (median, interquartile range 0.10, 0.05-0.2 MSEQ·kg(-1), P = 0.19). Pain scores indicated that patients were generally comfortable in the perioperative period.

CONCLUSIONS

The perioperative opiate requirements of pediatric patients who were successfully weaned after prolonged opiate use were similar to opiate-naïve patients. A history of prolonged opiate use alone does not necessitate special pain management for future procedures.

Neonatal drug withdrawal

Maternal use of certain drugs during pregnancy can result in transient neonatal signs consistent with withdrawal or acute toxicity or cause sustained signs consistent with a lasting drug effect. In addition, hospitalized infants who are treated with opioids or benzodiazepines to provide analgesia or sedation may be at risk for manifesting signs of withdrawal. This statement updates information about the clinical presentation of infants exposed to intrauterine drugs and the therapeutic options for treatment of withdrawal and is expanded to include evidence-based approaches to the management of the hospitalized infant who requires weaning from analgesics or sedatives.

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.

Use of methadone for prevention of opioid withdrawal in critically ill children

BACKGROUND

Opioids are commonly administered to critically ill children for analgesia and sedation, but many patients experience opioid withdrawal upon discontinuation. The authors' institution developed a protocol for using methadone to prevent opioid withdrawal in children who have received morphine by continuous IV infusion for 5 days or longer in the pediatric intensive care unit (PICU).

OBJECTIVES

The primary objectives were to determine if opioids were tapered according to the protocol and to determine the conversion ratio for IV morphine to oral methadone that was used. Secondary objectives were to describe the methadone dosage used and the clinical outcomes, to evaluate adjustments to methadone dosing, and to report the incidence of adverse effects.

METHODS

A retrospective analysis of charts was conducted for pediatric patients who had received morphine by continuous IV infusion for 5 days or longer followed by methadone in the PICU between May 2008 and August 2009. Validated scoring systems (the Withdrawal Assessment Tool and the State Behavioral Scale) were used to assess symptoms of withdrawal and degree of sedation, respectively.

RESULTS

Forty-three patients were included in the study, with median age of 8 months (range 0.25-201 months). For 31 patients (72%), the protocol was not used, and there were no patients for whom the protocol was followed to completion. The median duration of weaning was 10 days (range 0-91 days). The conversion ratio for IV morphine to oral methadone was 1:0.78 for anticipated 5-day weaning and 1:0.98 for anticipated 10-day weaning. During the first 10 days of weaning, 18 patients (42%) experienced withdrawal symptoms. The methadone dose was increased for 11 (26%) of the 43 patients. Patients were sedated for a median of 1 day (range 0-9 days), were comfortable for a median of 6.5 days (range 1-64 days), and were agitated for a median of 2.5 days (range 0-23 days). Naloxone was required for 2 patients.

CONCLUSIONS

The institution's methadone protocol was not followed consistently during the study period, and practices for transitioning from morphine by continuous IV infusion to methadone with tapering were also inconsistent. Further studies are needed to determine the optimal conversion ratio for morphine to methadone and the optimal tapering regimen to minimize withdrawal symptoms and adverse events.

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.

A trial of methadone tapering schedules in pediatric intensive care unit patients exposed to prolonged sedative infusions

OBJECTIVES

To compare the efficacy of a low-dose methadone tapering schedule to a high-dose methadone tapering schedule in pediatric intensive care unit patients exposed to infusions of fentanyl, with or without infusions of midazolam, for ≥ 5 days.

DESIGN

Prospective, double-blind, randomized trial.

SETTING

Pediatric intensive care unit in a tertiary care children's hospital.

PATIENTS

Seventy-eight patients, 74 of whom had been receiving infusions of both fentanyl and midazolam, were randomized. Forty-one patients were randomized to the low-dose methadone group and 37 were randomized to the high-dose methadone group. Sixty patients successfully completed the trial, 34 were in the low-dose methadone group, and 26 were in the high-dose methadone group.

INTERVENTIONS

Patients were randomized to receive methadone either at a starting dose of 0.1 mg/kg/dose (low-dose methadone group) or at a starting dose based on both the patient's weight and the most recent fentanyl infusion rate (high-dose methadone group). In each group, methadone was administered every 6 hrs for the first 24 hrs and then every 12 hrs for the second 24 hrs. The methadone was then decreased to once daily and tapered off over the next 10 days. Patients were monitored for withdrawal symptoms using the Modified Narcotic Withdrawal Score.

MEASUREMENTS AND MAIN RESULTS

The percentage of patients who successfully completed the 10-day methadone taper was the same in the low-dose methadone group as in the high-dose methadone group (56% vs. 62%; p = .79). Patients that failed to complete the assigned methadone taper had a greater total fentanyl dose and longer pediatric intensive care unit length of stay compared to patients who completed the assigned methadone taper.

CONCLUSIONS

Patients who received infusions of fentanyl for at least 5 days were just as likely to complete a low-dose methadone taper as a high-dose methadone taper. Because of the risks of both withdrawal and oversedation with any fixed methadone schedule, the methadone dose must be adjusted according to each patient's response.

Disaster after the plaster. Fentanyl withdrawal symptoms in a curable hospice patient

Opioids have been used for thousands of years for pain relief. Transdermal fentanyl (TDF) is a synthetic opioid that is prescribed for the treatment of chronic pain. This clinical lesson demonstrates that TDF may be easy to start but sometimes difficult to stop. Like any other opioid there is a substantial risk of physical dependence and subsequent withdrawal symptoms after discontinuation of the drug. Here, we present a case of a hospice patient who developed withdrawal symptoms after a first TDF tapering attempt according to the manufacturer's instructions. A second, more gradual tapering regimen did not result in withdrawal symptoms. The mechanisms and treatment modalities for physical dependence along with a tailor-made tapering strategy that is suitable for general practice are presented in this clinical lesson.

Dosing Evaluation of Continuous Intravenous Fentanyl Infusions in Overweight Children: A Pilot Study

OBJECTIVES

The purpose of this study was to assess the appropriateness of weight-based dosing of continuous intravenous infusion of fentanyl in overweight/obese versus normal-weight children admitted to the pediatric intensive care unit (PICU).

METHODS

This retrospective, pilot study included 5- to 12-year-old children admitted to the PICU over a 2-year period who received continuous intravenous infusion fentanyl for ≥ 4 days. The overweight/obese group included children with a body mass index (BMI) ≥ 85th percentile, while the control group included children with BMI &lt; 85th percentile. The primary objective was to compare the number of fentanyl continuous intravenous infusion dosage changes required per day to achieve adequate sedation between groups. Secondarily, opioid withdrawal symptoms following the discontinuation of fentanyl and concomitant sedative/analgesic regimens were analyzed between groups. Student t tests and chi-square analyses were performed as appropriate, with an a priori alpha of p≤0.05.

RESULTS

Sixteen normal-weight and 15 overweight/obese patients with 18 and 16 individual infusions were identified, respectively. No statistical difference was found between groups for the number of dosage changes per day, 0.92 versus 0.69 (p=0.16). Five patients in each group experienced withdrawal (p=0.71). The total number of concomitant bolus doses received was greater in the overweight/obese group but did not reach statistical significance.

CONCLUSIONS

There was a numerical, but statistically nonsignificant difference in the number of sedative/analgesic bolus doses and dosing changes per day between groups. Larger studies are warranted to determine the optimal dosing strategy for continuous intravenous infusion fentanyl in overweight/obese children.

Opioid tapering in children: a review of the literature

PURPOSE

To synthesize and critically analyze literature related to pediatric opioid withdrawal.

DESIGN

Critical review of literature related to pediatric opioid tapering and withdrawal.

METHODS

Studies published in peer-reviewed journals were systematically searched using Cochrane, MEDLINE, CINAHL, and PsychINFO. Articles meeting the inclusion criteria were reviewed and analyzed for themes and similarities.

FINDINGS

The majority of published research has focused on the episodic nature of withdrawal symptoms during opioid tapering. Only 1 study produced a valid and reliable pediatric opioid withdrawal symptom assessment-instrument and 1 study produced a valid and reliable pediatric opioid and benzodiazepine symptom assessment instrument. One study conducted in an adult and pediatric population analyzed the effect of the use of an opioid taper algorithm on occurrence and nature of opioid withdrawal symptoms.

CONCLUSIONS

The scope of research on pediatric opioid withdrawal is limited. Studies examining the effect of an opioid taper algorithm on incidence of withdrawal symptoms in children are sorely needed. Further validation of the 2 withdrawal assessment tools for children is warranted.

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.

Withdrawal from multiple sedative agent therapy in an infant: is dexmedetomidine the cause or the cure?

OBJECTIVE

To report withdrawal symptoms experienced by an infant following the prolonged use of dexmedetomidine.

DESIGN

Case report.

SETTING

Pediatric intensive care unit at a freestanding tertiary care children's hospital.

PATIENTS

One pediatric patient with respiratory failure following pertussis infection that required prolonged intubation and sedation. The patient required dexmedetomidine to maintain optimal sedation before ventilator weaning. Subsequent to receiving dexmedetomidine the patient developed withdrawal symptoms.

CONCLUSION

In patients who fail to achieve adequate sedation with the use of traditional medications, dexmedetomidine is an adequate alternative. However, abrupt discontinuation of dexmedetomidine may result in withdrawal symptoms that may be avoided with a dexmedetomidine taper.

Collaborative pediatric critical care research network: looking back and moving forward

OBJECTIVE

To update the pediatric critical care community on the progress of the Collaborative Pediatric Critical Care Research Network and plans for the future.

SETTING

The six sites, seven hospitals of the Collaborative Pediatric Critical Care Research Network.

RESULTS

From the time of its inception in August 2005, the Network has engaged in a number of observational and interventional trials, several of which are ongoing. Additional studies are in the planning stages. To date, these studies have resulted in the publication of six manuscripts and five abstracts, with five additional manuscripts accepted and in press.

CONCLUSION

The Network remains committed to its stated goal "to initiate a multicentered program designed to investigate the safety and efficacy of treatment and management strategies to care for critically ill children, as well as the pathophysiologic basis of critical illness and injury in childhood."

α2-Receptor Agonists for Treatment and Prevention of Iatrogenic Opioid Abstinence Syndrome in Critically Ill Patients

Objective:

To review the literature regarding the use of α2-agonists in the treatment and prevention of iatrogenic opioid abstinence syndrome (IOAS) in critically ill patients.

Data Sources:

Primary literature was identified through a search of MEDLINE (1950–June 2009), EMBASE (1988–June 2009), International Pharmaceutical Abstracts (1970–June 2009), and the Cochrane Library (1996–June 2009), using the names of individual α2-agonists and the following key words: children, opioid withdrawal, opioid, and adult. Relevant abstracts from the Society of Critical Care Medicine, reference citations from selected articles, and manufacturers’ product information were also reviewed.

Study Selection and Data Extraction:

All English-language articles identified from the data sources were evaluated. Three retrospective studies and 6 case reports/series representing 44 patients were included for analysis.

Data Synthesis:

Central α2-agonists are thought to minimize symptoms of IOAS by decreasing presynaptic outflow of catecholamines. Successful use of clonidine and dexmedetomidine for management of IOAS has been reported. Lofexidine, an α2-agonist not yet approved in the US, may offer similar withdrawal symptom relief but has yet to be studied in the intensive care setting. Although the quality of studies identified was limited, preliminary evidence does provide some support for the use of transdermal clonidine and injectable dexmedetomidine in the treatment and prevention of IOAS. These agents were shown to facilitate discontinuation of opioids and to minimize withdrawal symptoms with few reported adverse events.

Conclusions:

Central α2-agonists appear to be effective and safe second-line agents for treatment and prevention of IOAS. Further studies should be conducted to determine their role in the therapy of patients with IOAS.

Sedation and analgesia in the pediatric intensive care unit following laryngotracheal reconstruction

BACKGROUND

Children undergoing laryngotracheal reconstruction (LTR) may remain electively intubated in the pediatric intensive care unit (PICU) for several days following surgery to facilitate wound healing. These patients require sedation and analgesia with or without neuromuscular blockade in order to prevent excessive head and neck movement with resultant tension on the tracheal anastomosis. Achieving this level of immobility features in caring for these children.

AIM

The aims of this article are to describe a variety of commonly used sedation and analgesic agents and to provide guidance as to their optimal use following LTR.

Opioid and benzodiazepine withdrawal syndromes in the paediatric intensive care unit: a review of recent literature

AIMS AND OBJECTIVES

This paper aims to critically review and analyse available literature to inform and advance patient care.

BACKGROUND

Withdrawal syndromes related to the routine administration of sedation and analgesia in paediatric intensive care unit (PICU) have been recognized since the 1990 s. Common symptoms include tremors, agitation, inconsolable crying and sleeplessness.

SEARCH STRATEGIES

A critical review was undertaken to assess developments in this area. Four databases were searched using Ovid Online. These were Ovid Medline, CINAHL, BNI and Embase. Key terms included were 'Paediatric', 'Sedation', 'Withdrawal' and 'Intensive care'.

INCLUSION AND EXCLUSION CRITERIA

Articles from 1980 onwards were reviewed for their relevance to paediatric iatrogenic withdrawal. Additionally, seminal work from the 1970s was included. Because of the scarcity of literature, relevant editorials and opinion pieces were included.

RESULTS

A total of 2,232,586 papers resulted from keyword searches. Use of Boolean operators to combine terms reduced the number of results to 62. Exclusion criteria reduced the number of suitable papers to 20. Tracking reference lists yielded a further 18 papers. In total, 38 papers were retrieved examining 1375 patients. Four papers surveyed drug usage on PICU, 14 listed withdrawal symptoms, 4 described the frequency of withdrawal in the PICU population, 9 described risk factors, 4 presented or validated clinical tools and 14 describe treatment strategies.

CONCLUSIONS

Withdrawal syndromes may affect 20% of exposed children and are related to infusion duration and total dose. Fifty-one symptoms are described in the literature. Future studies need accurate, validated clinical tools to be effective. Risk factors, signs and symptoms have been identified, and validation studies must now take place.

RELEVANCE TO CLINICAL PRACTICE

Withdrawal syndromes continue to be widespread and difficult to diagnose. Awareness of their causes and treatments should influence clinical decisions at the bedside.

Sedation and analgesia in the pediatric Intensive Care Unit following laryngotracheal reconstruction

Deep levels of sedation and analgesia are needed in the majority of children who require prolonged tracheal intubation after laryngotracheal reconstruction (LTR). Drug doses may be determined most appropriately using validated scoring tools for sedation and analgesia; these scales continue to evolve and are used with increasing regularity in the pediatric intensive care unit (PICU). In this presentation, the validated scoring tools used to assess sedation and analgesia are reviewed, and specific agents used to manage sedation, analgesia, and neuromuscular blockade in the PICU after LTR are discussed.

Withdrawal symptoms in critically ill children after long-term administration of sedatives and/or analgesics: a first evaluation

OBJECTIVE

To establish frequencies of benzodiazepine and opioid withdrawal symptoms, and correlations with total doses and duration of administration.

DESIGN

A prospective, repeated-measures design.

SETTING

Two pediatric intensive care units in a university children's hospital.

PATIENTS

Seventy-nine children, aged 0 days to 16 yrs, who received intravenous midazolam and/or opioids for >5 days.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Pediatric intensive care unit nurses assessed withdrawal symptoms using the Sophia Benzodiazepine and Opioid Withdrawal Checklist, which includes all withdrawal symptoms (n = 24) described in the pediatric literature. Over 6 months, 2188 observations in 79 children were recorded. Forty-two percent of observations were performed within 24 hrs after tapering off or discontinuation of medication. Symptoms representing overstimulation of the central nervous system, such as anxiety, agitation, grimacing, sleep disturbance, increased muscle tension, and movement disorder, were observed in >10% of observations. Of symptoms reflecting gastrointestinal dysfunction, diarrhea and gastric retention were most frequently observed. Tachypnea, fever, sweating, and hypertension as manifestations of autonomic dysfunction were observed in >13% of observations. The Spearman's rank-correlation coefficient between total doses of midazolam and maximum sum score (of the Sophia Benzodiazepine and Opioid Withdrawal Checklist) was .51 (p < 0.001). The correlation between total doses of opioids and the maximum sum score was .39 (p < 0.01). A significant correlation (.52; p < 0.001) was also found between duration of use and maximum sum score.

CONCLUSIONS

This is the first study to report frequencies of all 24 withdrawal symptoms observed in children after decrease or discontinuation of benzodiazepines and/or opioids. Agitation, anxiety, muscle tension, sleeping <1 hr, diarrhea, fever, sweating, and tachypnea were observed most frequently. Longer duration of use and high dosing are risk factors for development of withdrawal symptoms in children.

[Weaning from the ventilator modalities and consequences]

Only few studies have focused on the issues raised by discontinuing sedation in ICU patients. Several lines of evidence allow defining the risk factors for the occurrence of a weaning syndrome due to discontinuation of sedatives and analgesics in ICU patients. These primarily include a prolonged (more than seven days) period of continuous intravenous administration of high doses of hypnotics and opioids. Weaning from sedation is tightly linked to weaning from the ventilator and this area should be the target of research work in the near future.

Effect of low-dose naloxone infusion on fentanyl requirements in critically ill children

OBJECTIVE

Sedating critically ill patients often involves prolonged opioid infusions causing opioid tolerance. Naloxone has been hypothesized to limit opioid tolerance by decreasing adenylate cyclase/cyclic adenosine monophosphate activation. The study purpose was to investigate the effect of low-dose naloxone on the maximum cumulative daily fentanyl dose in critically ill children.

METHODS

We conducted a double-blinded, randomized, placebo-control trial from December 2002 through July 2004 in a university PICU. We enrolled 82 children age 1 day to 18 years requiring mechanical ventilation and fentanyl infusions anticipated to last for >4 days were eligible for enrollment. Those receiving additional oral analgesia or sedation, having a history of drug dependence or withdrawal, or having significant neurologic, renal, or hepatic disease were excluded. In addition to fentanyl infusions, patients received low-dose naloxone or placebo infusions. Medications were adjusted using the Modified Motor Activity Assessment Scale. Withdrawal was monitored using the Modified Narcotic Withdrawal Scale. Intervention was a low-dose naloxone infusion (0.25 microg/kg per hour) and the main outcome variable was the maximum cumulative daily fentanyl dose (micrograms per kilogram per day).

RESULTS

There was no difference in the maximum cumulative daily fentanyl dose between patients treated with naloxone (N = 37) or those receiving placebo (N = 35). Adjustment for the starting fentanyl dose also failed to reveal group differences. Total fentanyl dose received throughout the study in the naloxone group (360 microg/kg) versus placebo (223 microg/kg) was not statistically different. Placebo patients trended toward fewer rescue midazolam boluses (10.7 vs 17.8), lower total midazolam dose (11.6 mg/kg vs 23.9 mg/kg), and fewer rescue fentanyl boluses (18.5 vs 23.9).

CONCLUSIONS

We conclude that administration of low-dose naloxone (0.25 microg/kg per hour) does not decrease fentanyl requirements in critically ill, mechanically ventilated children.

Bispectral Index asymmetry and COMFORT score in paediatric intensive care patients

BACKGROUND

The Bispectral Index (BIS) monitor has been suggested as a potential tool to measure depth of sedation in paediatric intensive care unit (PICU) patients. The primary aim of our observational study was to assess the difference in BIS values between the left and right sides of the brain. Secondary aims were to compare BIS and COMFORT score and to assess change in BIS with tracheal suctioning.

METHODS

Nineteen ventilated and sedated PICU patients had paediatric BIS sensors applied to either side of their forehead. Each patient underwent physiotherapy involving tracheal suctioning. Their BIS data and corresponding COMFORT score, assessment as by their respective nurses, were recorded before, during, and after physiotherapy.

RESULTS

Seven patients underwent more than one physiotherapy session; therefore, 28 sets of data were collected. The mean BIS difference values (and 95% CI) between left BIS and right BIS for pre-, during, and post-physiotherapy periods were 9.2 (5.9-12.5), 15.8 (11.9-19.7), and 7.5 (5.2-9.7), respectively. Correlation between mean BIS, left brain BIS, and right brain BIS to COMFORT score was highly significant (P<0.001 for all three) during the pre- and post-physiotherapy period, but less so during the stimulated physiotherapy period (P=0.044, P=0.014, and P=0.253, respectively).

CONCLUSIONS

A discrepancy between left and right brain BIS exists, especially when the patient is stimulated. COMFORT score and BIS correlate well between light and moderate sedation.

Minimizing tolerance and withdrawal to prolonged pediatric sedation: case report and review of the literature

Midazolam and fentanyl infusions are commonly used for prolonged sedation and analgesia in the pediatric intensive care setting. Tolerance and withdrawal are major concerns when these infusions are used for days or weeks. Here, we review the current approaches to prolonged pediatric sedation using midazolam and fentanyl and discuss newer strategies to avoid tolerance and withdrawal syndromes. We report the case of a pediatric burn patient who developed tolerance syndrome and a movement disorder in our institution. We also review the relevant literature and methods of minimizing tolerance and withdrawal. Prolonged sedation is often necessary in treating critically ill children, and tolerance and abstinence syndrome can complicate a successful recovery. Scoring systems can be used to minimize oversedation and to titrate effectively. "Drug cycling," "wake-up protocols," and weaning regimens, possibly combined with adjuvant drugs, are being implemented successfully. Such novel approaches may decrease the incidence of tolerance and withdrawal associated with prolonged sedative and analgesic use.

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.

Withdrawal symptoms in children after long-term administration of sedatives and/or analgesics: a literature review. "Assessment remains troublesome"

BACKGROUND

Prolonged administration of benzodiazepines and/or opioids to children in a pediatric intensive care unit (PICU) may induce physiological dependence and withdrawal symptoms.

OBJECTIVE

We reviewed the literature for relevant contributions on the nature of these withdrawal symptoms and on availability of valid scoring systems to assess the extent of symptoms.

METHODS

The databases PubMed, CINAHL, and Psychinfo (1980-June 2006) were searched using relevant key terms.

RESULTS

Symptoms of benzodiazepine and opioid withdrawal can be classified in two groups: central nervous system effects and autonomic dysfunction. However, symptoms of the two types show a large overlap for benzodiazepine and opioid withdrawal. Symptoms of gastrointestinal dysfunction in the PICU population have been described for opioid withdrawal only. Six assessment tools for withdrawal symptoms are used in children. Four of these have been validated for neonates only. Two instruments are available to specifically determine withdrawal symptoms in the PICU: the Sedation Withdrawal Score (SWS) and the Opioid Benzodiazepine Withdrawal Scale (OBWS). The OBWS is the only available assessment tool with prospective validation; however, the sensitivity is low.

CONCLUSIONS

Withdrawal symptoms for benzodiazepines and opioids largely overlap. A sufficiently sensitive instrument for assessing withdrawal symptoms in PICU patients needs to be developed.