Ketamine exposure during embryogenesis inhibits cellular proliferation in rat fetal cortical neurogenic regions.

BACKGROUND: Developmental neurotoxicity of ketamine, an N-methyl-D-aspartate receptor antagonist, must be considered due to its widespread uses for sedation/analgesia/anesthesia in pediatric and obstetric settings. Dose-dependent effects of ketamine on cellular proliferation in the neurogenic regions of rat fetal cortex [ventricular zone (VZ) and subventricular zone (SVZ)] were investigated in this in vivo study. METHODS: Timed-pregnant Sprague-Dawley rats at embryonic day 17 (E17) were given with different doses of ketamine intraperitoneally (0, 1, 2, 10, 20, 40, and 100 mg/kg). Proliferating cells in the rat fetal brains were labeled by injecting 100 mg/kg of 5-bromo-2'-deoxyuridine (BrdU) intraperitoneally. BrdU-labeled cells were detected by immunostaining methods. The numbers of BrdU-positive cells in VZ and SVZ of rat fetal cortex were employed to quantify proliferation in the developing rat cortex. RESULTS: Ketamine dose-dependently reduced the number of BrdU-positive cells in VZ (P < 0.001) and SVZ (P < 0.001) of the rat fetal cortex. SVZ showed greater susceptibility to ketamine-induced reduction of proliferation in rat fetal cortex, occurring even at clinically relevant doses (2 mg/kg). CONCLUSION: These data suggest that exposure to ketamine during embryogenesis can dose-dependently inhibit the cellular proliferation in neurogenic regions of the rat fetal cortex.

[Sedation and analgesia practices among Spanish neonatal intensive care units]. / Manejo de la sedación y la analgesia en unidades de cuidados intensivos neonatales españolas.

INTRODUCTION: Pain management and sedation is a priority in neonatal intensive care units. A study was designed with the aim of determining current clinical practice as regards sedation and analgesia in neonatal intensive care units in Spain, as well as to identify factors associated with the use of sedative and analgesic drugs. METHOD: A multicenter, observational, longitudinal and prospective study. RESULTS: Thirty neonatal units participated and included 468 neonates. Of these, 198 (42,3%) received sedatives or analgesics. A total of 19 different drugs were used during the study period, and the most used was fentanyl. Only fentanyl, midazolam, morphine and paracetamol were used in at least 20% of the neonates who received sedatives and/or analgesics. In infusions, 14 different drug prescriptions were used, with the most frequent being fentanyl and the combination of fentanyl and midazolam. The variables associated with receiving sedation and/or analgesia were, to have required invasive ventilation (P<.001; OR=23.79), a CRIB score >3 (P=.023; OR=2.26), the existence of pain evaluation guides in the unit (P<.001; OR=3.82), and a pain leader (P=.034; OR=2.35). CONCLUSIONS: Almost half of the neonates admitted to intensive care units receive sedatives or analgesics. There is significant variation between Spanish neonatal units as regards sedation and analgesia prescribing. Our results provide evidence on the "state of the art", and could serve as the basis of preparing clinical practice guidelines at a national level.

Multiple intravenous doses of paracetamol result in a predictable pharmacokinetic profile in very preterm infants.

AIM: The therapeutic options available to treat neonatal pain are limited, and one alternative for nonopioid systemic treatment is paracetamol. However, pharmacokinetic data from prolonged administration of intravenous paracetamol in neonates are limited. The aim of this study was to present pharmacokinetics after multiple dose of intravenous paracetamol in very preterm infants of <32 weeks' gestation. METHODS: Fifteen very preterm infants received five, six-hourly doses of intravenous paracetamol (7.5 mg/kg). Blood samples were taken to measure paracetamol, glutathione and hepatic function, together with urine samples for paracetamol metabolites. RESULTS: A two-compartment pharmacokinetic model gave the best fit for all individual patients and resulted in a predictable pharmacokinetic profile. The estimated pharmacokinetic population parameters were volume of distribution 0.764 ± 0.225 L/kg, elimination rate constant (ke ) 0.117 ± 0.091/h and intercompartment rate constants k12 0.607 ± 0.734/h and k21 1.105 ± 0.762/h. CONCLUSION: Our study found that multiple doses of intravenous paracetamol resulted in a predictable pharmacokinetic profile in very preterm infants. Increases in postmenstrual age and weight were associated with increased clearance. No evidence of hepatotoxicity was found.

Does neonatal pain management in intensive care units differ between night and day? An observational study.

OBJECTIVE: To determine whether analgesic use for painful procedures performed in neonates in the neonatal intensive care unit (NICU) differs during nights and days and during each of the 6 h period of the day. DESIGN: Conducted as part of the prospective observational Epidemiology of Painful Procedures in Neonates study which was designed to collect in real time and around-the-clock bedside data on all painful or stressful procedures. SETTING: 13 NICUs and paediatric intensive care units in the Paris Region, France. PARTICIPANTS: All 430 neonates admitted to the participating units during a 6-week period between September 2005 and January 2006. DATA COLLECTION: During the first 14 days of admission, data were collected on all painful procedures and analgesic therapy. The five most frequent procedures representing 38 012 of all 42 413 (90%) painful procedures were analysed. INTERVENTION: Observational study. MAIN OUTCOME ASSESSMENT: We compared the use of specific analgesic for procedures performed during each of the 6 h period of a day: morning (7:00 to 12:59), afternoon, early night and late night and during daytime (morning+afternoon) and night-time (early night+late night). RESULTS: 7724 of 38 012 (20.3%) painful procedures were carried out with a specific analgesic treatment. For morning, afternoon, early night and late night, respectively, the use of analgesic was 25.8%, 18.9%, 18.3% and 18%. The relative reduction of analgesia was 18.3%, p<0.01, between daytime and night-time and 28.8%, p<0.001, between morning and the rest of the day. Parental presence, nurses on 8 h shifts and written protocols for analgesia were associated with a decrease in this difference. CONCLUSIONS: The substantial differences in the use of analgesics around-the-clock may be questioned on quality of care grounds.

Physicians' conceptualization of "closure" as a benefit of physician-parent follow-up meetings after a child's death in the pediatric intensive care unit.

We examined physicians' conceptualization of closure as a benefit of follow-up meetings with bereaved parents. The frequency of use and the meaning of the word "closure" were analyzed in transcripts of interviews with 67 critical care physicians affiliated with the Collaborative Pediatric Critical Care Research Network. In all, 38 physicians (57 percent) used the word "closure" at least once (median: 2; range: 1 to 7), for a total of 86 times. Physicians indicated that closure is a process or trajectory rather than an achievable goal. They also indicated that parents and physicians can move toward closure by gaining a better understanding of the causes and circumstances of the death and by reconnecting with, or resolving relationships between, parents and health professionals. Physicians suggested that a primary reason to conduct follow-up meetings is that such meetings offer parents and physicians an opportunity to move toward closure. Future research should attempt to determine whether followup meetings reduce the negative effects of bereavement for parents and physicians.

Developmental neurotoxicity of ketamine in pediatric clinical use.

Ketamine is widely used as an anesthetic, analgesic, and sedative in pediatric clinical practice and it is also listed as an illicit drug by most countries. Recent in vivo and in vitro animal studies have confirmed that ketamine can induce neuronal cell death in the immature brain, resulting from widespread neuronal apoptosis. These effects can disturb normal development further altering the structure and functions of the brain. Our recent studies further indicate that ketamine can alter neurogenesis from neural stem progenitor cells in the developing brain. Taken together, these findings identify a novel complication associated with ketamine use in premature infants, term newborns, and pregnant women. Recent data on the developmental neurotoxicity of ketamine are reviewed with proposed future directions for evaluating the safety of ketamine in these patient populations.

Baseline serum concentrations of zinc, selenium, and prolactin in critically ill children.

OBJECTIVES: To describe serum concentrations of zinc, selenium, and prolactin in critically ill children within 72 hours of PICU admission, and to investigate relationships between these immunomodulators and lymphopenia. DESIGN: An analysis of baseline data collected as part of the multicenter Critical Illness Stress Induced Immune Suppression (CRISIS) Prevention Trial. SETTING: PICUs affiliated with the Collaborative Pediatric Critical Care Research Network. PATIENTS: All children enrolled in the CRISIS Prevention Trial that had baseline serum samples available for analysis. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Of 293 critically ill children enrolled in the CRISIS Prevention Trial, 284 had baseline serum samples analyzed for prolactin concentration, 280 for zinc concentration, and 278 for selenium concentration within 72 hours of PICU admission. Lymphocyte counts were available for 235 children. Zinc levels ranged from nondetectable (< 0.1 µg/mL) to 2.87 µg/mL (mean 0.46 µg/mL and median 0.44 µg/mL) and were below the normal reference range for 235 (83.9%) children. Selenium levels ranged from 26 to 145 ng/mL (mean 75.4 ng/mL and median 74.5 ng/mL) and were below the normal range for 156 (56.1%) children. Prolactin levels ranged from nondetectable (< 1 ng/mL) to 88 ng/mL (mean 12.2 ng/mL and median 10 ng/mL). Hypoprolactinemia was present in 68 (23.9%) children. Lymphopenia was more likely in children with zinc levels below normal than those with zinc levels within or above the normal range (82 of 193 [42.5%] vs. 10 of 39 [25.6%], p = 0.0498). Neither selenium nor prolactin concentrations were associated with lymphopenia (p = 1.0 and p = 0.72, respectively). CONCLUSIONS: Serum concentrations of zinc, selenium, and prolactin are often low in critically ill children early after PICU admission. Low serum zinc levels are associated with lymphopenia, whereas low selenium and prolactin levels are not. The implications of these findings and the mechanisms by which they occur merit further study.

The role of the Data and Safety Monitoring Board in a clinical trial: the CRISIS study.

OBJECTIVES: Randomized clinical trials are commonly overseen by a Data and Safety Monitoring Board comprised of experts in medicine, ethics, and biostatistics. Data and Safety Monitoring Board responsibilities include protocol approval, interim review of study enrollment, protocol compliance, safety, and efficacy data. Data and Safety Monitoring Board decisions can affect study design and conduct, as well as reported findings. Researchers must incorporate Data and Safety Monitoring Board oversight into the design, monitoring, and reporting of randomized trials. DESIGN: Case study, narrative review. METHODS: The Data and Safety Monitoring Board's role during the comparative pediatric Critical Illness Stress-Induced Immune Suppression (CRISIS) Prevention Trial is described. FINDINGS: The National Institutes of Health-appointed CRISIS Data and Safety Monitoring Board was charged with monitoring sample size adequacy and feasibility, safety with respect to adverse events and 28-day mortality, and efficacy with respect to the primary nosocomial infection/sepsis outcome. The Federal Drug Administration also requested Data and Safety Monitoring Board interim review before opening CRISIS to children below 1 yr of age. The first interim analysis found higher 28-day mortality in one treatment arm. The Data and Safety Monitoring Board maintained trial closure to younger children and requested a second interim data review 6 months later. At this second meeting, mortality was no longer of concern, whereas a weak efficacy trend of lower infection/sepsis rates in one study arm emerged. As over 40% of total patients had been enrolled, the Data and Safety Monitoring Board elected to examine conditional power and unmask treatment arm identities. On finding somewhat greater efficacy in the placebo arm, the Data and Safety Monitoring Board recommended stopping CRISIS due to futility. CONCLUSIONS: The design and operating procedures of a multicenter randomized trial must consider a pivotal Data and Safety Monitoring Board role. Maximum study design flexibility must be allowed, and investigators must be prepared for protocol modifications due to interim findings. The Data and Safety Monitoring Board must have sufficient clinical and statistical expertise to assess potential importance of interim treatment differences in the setting of multiple looks at accumulating data with numerous outcomes and subgroups.

Ketamine alters the neurogenesis of rat cortical neural stem progenitor cells.

OBJECTIVE: High doses or prolonged exposure to ketamine increase neuronal apoptosis in the developing brain, although effects on neural stem progenitor cells remain unexplored. This study investigated dose- and time-dependent responses to ketamine on cell death and neurogenesis in cultured rat fetal cortical neural stem progenitor cells. DESIGN: Laboratory-based study. SETTING: University research laboratory. SUBJECT: Sprague-Dawley rats. INTERVENTIONS: Neural stem progenitor cells were isolated from the cortex of Sprague-Dawley rat fetuses on embryonic day 17. In dose-response experiments, cultured neural stem progenitor cells were exposed to different concentrations of ketamine (0-100 µM) for 24 hrs. In time-course experiments, neural stem progenitor cells cultures were exposed to 10 µM ketamine for different durations (0-48 hrs). MEASUREMENTS AND MAIN RESULTS: Apoptosis and necrosis in neural stem progenitor cells were assessed using activated caspase-3 immunostaining and lactate dehydrogenase assays, respectively. Proliferative changes in neural stem progenitor cells were detected using bromo-deoxyuridine incorporation and Ki67 immunostaining. Neuronal differentiation was assessed using Tuj-1 immunostaining. Cultured neural stem progenitor cells were resistant to apoptosis and necrosis following all concentrations and durations of ketamine exposure tested. Ketamine inhibited proliferation with decreased numbers of bromo-deoxyuridine-positive cells following ketamine exposure to 100 µM for 24 hrs (p<.005) or 10 µM for 48 hrs (p< .01), and reduced numbers of Ki67-positive cells following exposure to ketamine concentration>10 µM for 24 hrs (p<.001) or at 10 µM for 48 hrs (p<.01). Ketamine enhanced neuronal differentiation, with all ketamine concentrations increasing Tuj-1-positive neurons (p<.001) after 24-hrs of exposure. This also occurred with all exposures to 10 µM ketamine for >8 hrs (p<.001). CONCLUSIONS: Clinically relevant concentrations of ketamine do not induce cell death in neural stem progenitor cells via apoptosis or necrosis. Ketamine alters the proliferation and increases the neuronal differentiation of neural stem progenitor cells isolated from the rat neocortex. These studies imply that ketamine exposure during fetal or neonatal life may alter neurogenesis and subsequent brain development.

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.

A pilot study of preemptive morphine analgesia in preterm neonates: effects on head circumference, social behavior, and response latencies in early childhood.

Use of preemptive analgesia in Neonatal Intensive Care Units is recommended for severe and/or invasive procedures. However, the potential long-term consequences of such analgesia, which may be prolonged, are only beginning to be studied. In this pilot study, a subset of subjects previously enrolled in the Neurological Outcomes and Preemptive Analgesia in Neonates (NEOPAIN) trial was assessed at early childhood. These ex-preterm infants (born at 23-32 weeks of gestational age) required intubation within 72 h postpartum and were randomized to receive either preemptive morphine analgesia (maximum of 14 days) or placebo within 8h post-intubation. At 5-7 years of age, neuropsychological outcomes, morphometrics, adaptive behavior, parent-rated behavior, motivation, and short-term memory were measured. Although overall IQ and academic achievement did not differ between the morphine treated (n=14) and placebo (n=5) groups, preemptive morphine analgesia was associated with distinct differences in other outcome variables. Head circumference of morphine treated children was approximately 7% smaller (Cohen'sd: 2.83, effect size large) and body weight was approximately 4% less (Cohen'sd: 0.81, effect size large); however, height did not differ. In the short-term memory task (delayed matching to sample), morphine treated children exhibited significantly longer choice response latencies than placebo children (3.86±0.33 and 2.71±0.24 s, respectively) (p<0.03) and completed approximately 27% less of the task than placebo children (Cohen'sd: 0.96, effect size large). Parents described morphine treated children as having more social problems, an effect specific to creating and maintaining friendships (Cohen'sd: -0.83, effect size large). Despite the small sample size and the preliminary nature of this study, these results are strongly suggestive of long-lasting effects of preemptive morphine analgesia. A larger investigation with more comprehensive assessments of some of these key features will enable a more complete understanding of the relationship between preemptive morphine treatment and long-term neurocognitive, behavioral, and adaptive outcomes.

The randomized comparative pediatric critical illness stress-induced immune suppression (CRISIS) prevention trial.

OBJECTIVES: Nosocomial infection/sepsis occurs in up to 40% of children requiring long-term intensive care. Zinc, selenium, glutamine, metoclopramide (a prolactin secretalogue), and/or whey protein supplementation have been effective in reducing infection and sepsis in other populations. We evaluated whether daily nutriceutical supplementation with zinc, selenium, glutamine, and metoclopramide, compared to whey protein, would reduce the occurrence of nosocomial infection/sepsis in this at-risk population. DESIGN: Randomized, double-blinded, comparative effectiveness trial. SETTING: Eight pediatric intensive care units in the National Institutes of Child Health and Human Development Collaborative Pediatric Critical Care Research Network. PATIENTS: Two hundred ninety-three long-term intensive care patients (age 1-17 yrs) expected to require >72 hrs of invasive care. INTERVENTIONS: Patients were stratified according to immunocompromised status and center and then were randomly assigned to receive daily enteral zinc, selenium, glutamine, and intravenous metoclopramide (n = 149), or daily enteral whey protein (n = 144) and intravenous saline for up to 28 days of intensive care unit stay. The primary end point was time to development of nosocomial sepsis/infection. The analysis was intention to treat. MEASUREMENTS AND MAIN RESULTS: There were no differences by assigned treatment in the overall population with respect to time until the first episode of nosocomial infection/sepsis (median whey protein 13.2 days vs. zinc, selenium, glutamine, and intravenous metoclopramide 12.1 days; p = .29 by log-rank test) or the rate of nosocomial infection/sepsis (4.83/100 days whey protein vs. 4.99/100 days zinc, selenium, glutamine, and intravenous metoclopramide; p = .81). Only 9% of the 293 subjects were immunocompromised and there was a reduction in rate of nosocomial infection/sepsis with zinc, selenium, glutamine, and intravenous metoclopramide in this immunocompromised group (6.09/100 days whey protein vs. 1.57/100 days zinc, selenium, glutamine, and intravenous metoclopramide; p = .011). CONCLUSION: Compared with whey protein supplementation, zinc, selenium, glutamine, and intravenous metoclopramide conferred no advantage in the immune-competent population. Further evaluation of zinc, selenium, glutamine, and intravenous metoclopramide supplementation is warranted in the immunocompromised long-term pediatric intensive care unit patient.

The effect of tai chi on cognition in elders with cognitive impairment.

This one-arm pilot study investigated the effect of tai chi on cognition in elders with cognitive impairment. Although no significant difference existed between pre- and post-test performance on all cognition measures, a dose-response relationship was demonstrated between attendance and some cognition measures.

Follow-up study of complicated grief among parents eighteen months after a child's death in the pediatric intensive care unit.

OBJECTIVE: We previously demonstrated that parents whose children die in a pediatric intensive care unit (PICU) have a high level of complicated grief symptoms 6 months after the death. In this study, we investigate the change in the extent of complicated grief symptoms among these parents between 6 and 18 months postdeath and identify factors predicting improvement. METHODS: One hundred thirty-eight parents of 106 children completed surveys at 6 and 18 months. Surveys included the Inventory of Complicated Grief (ICG), measures of grief avoidance, attachment, caregiving and social support, and demographics. Multivariable analysis was performed using generalized estimating equations to identify characteristics independently associated with improvement in ICG score. RESULTS: ICG scores were 33.4 ± 13.6 at 6 months and 28.0 ± 13.5 at 18 months, representing an improvement in ICG score of 5.4 + 8.0 (95% confidence interval [CI] 4.1-6.8, p < 0.001). Variables independently associated with greater improvement in ICG score included traumatic death and greater grief avoidance. Variables independently associated with less improvement included being the biological parent and having more responsive caregiving. Parents with one or two surviving children had more improvement in ICG score than those with no surviving children whereas parents with three or more surviving children had less improvement. CONCLUSION: Complicated grief symptoms decrease among parents between 6 and 18 months after their child's death in the PICU; however, high symptom levels persists for some. Better understanding of the trajectory of complicated grief will allow parents at risk for persistent distress to receive professional support.

Physicians' experiences and perspectives regarding follow-up meetings with parents after a child's death in the pediatric intensive care unit.

OBJECTIVE: To investigate critical care physicians' experiences and perspectives regarding follow-up meetings with parents after a child's death in the pediatric intensive care unit. Parents of children who die in the pediatric intensive care unit often desire a follow-up meeting with the physicians who cared for their child. DESIGN: Semistructured, audio-recorded telephone interviews. SETTING: Six clinical centers affiliated with the Eunice Kennedy Shriver National Institute of Child Health and Human Development Collaborative Pediatric Critical Care Research Network. PARTICIPANTS: Seventy critical care physicians (i.e., attendings and fellows) practicing or training at a Child Health and Human Development Collaborative Pediatric Critical Care Research Network clinical center between February 1, 2008 and June 30, 2008. MEASUREMENTS AND MAIN RESULTS: Twenty-three (33%) physicians reported never participating in a follow-up meeting with bereaved parents; 22 (31%) participated in one to five meetings; and 25 (36%) participated in more than five meetings. Of those with prior experience, 44 (94%) met with parents at the hospital and 40 (85%) met within 3 months of the death. Meeting content included discussing autopsy, parent questions, hospital course, cause of death, genetic risk, bereavement services, and legal or administrative issues; providing emotional support; and receiving parent feedback. Forty (85%) physicians perceived the meetings to be beneficial to families, and 35 (74%) to physicians. Barriers included time and scheduling, family and physician unwillingness, distance and transportation, language and cultural issues, parent anger, and lack of a system for meeting initiation and planning. CONCLUSIONS: Critical care physicians have a wide range of experience conducting follow-up meetings with bereaved parents. Although physicians perceive benefits to follow-up meetings, barriers exist that interfere with their implementation in clinical practice.

Endocrinopathies in the cardiac ICU.

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

The Collaborative Pediatric Critical Care Research Network Critical Pertussis Study: collaborative research in pediatric critical care medicine.

OBJECTIVE: To provide an updated overview of critical pertussis to the pediatric critical care community and describe a study of critical pertussis recently undertaken. SETTING: The six sites, seven hospitals of the Collaborative Pediatric Critical Care Research Network, and 17 outside sites at academic medical centers with pediatric intensive care units. RESULTS: Despite high coverage for childhood vaccination, pertussis causes substantial morbidity and mortality in US children, especially among infants. In pediatric intensive care units, Bordetella pertussis is a community-acquired pathogen associated with critical illness and death. The incidence of medical and developmental sequelae in critical pertussis survivors remains unknown, and the appropriate strategies for treatment and support remain unclear. The Collaborative Pediatric Critical Care Research Network Critical Pertussis Study has begun to evaluate critical pertussis in a prospective cohort. CONCLUSION: Research is urgently needed to provide an evidence base that might optimize management for critical pertussis, a serious, disabling, and too often fatal illness for U.S. children and those in the developing world.

Complicated grief and associated risk factors among parents following a child's death in the pediatric intensive care unit.

OBJECTIVE: To investigate the extent of complicated grief symptoms and associated risk factors among parents whose child died in a pediatric intensive care unit. DESIGN: Cross-sectional survey conducted by mail and telephone. SETTING: Seven children's hospitals affiliated with the Collaborative Pediatric Critical Care Research Network from January 1, 2006, to June 30, 2008. PARTICIPANTS: Two hundred sixty-one parents from 872 families whose child died in a pediatric intensive care unit 6 months earlier. MAIN EXPOSURE: Assessment of potential risk factors, including demographic and clinical variables, and parent psychosocial characteristics, such as attachment style, caregiving style, grief avoidance, and social support. MAIN OUTCOME MEASURE: Parent report of complicated grief symptoms using the Inventory of Complicated Grief. Total scale range is from 0 to 76; scores of 30 or higher suggest complicated grief. RESULTS: Mean (SD) Inventory of Complicated Grief scores among parents were 33.7 (14.1). Fifty-nine percent of parents (95% confidence interval, 53%-65%) had scores of 30 or higher. Variables independently associated with higher symptom scores in multivariable analysis included being the biological mother or female guardian, trauma as the cause of death, greater attachment-related anxiety and attachment-related avoidance, and greater grief avoidance. CONCLUSIONS: Parents who responded to our survey experienced a high level of complicated grief symptoms 6 months after their child's death in the pediatric intensive care unit. However, our estimate of the extent of complicated grief symptoms may be biased because of a high number of nonresponders. Better understanding of complicated grief and its risk factors among parents will allow those most vulnerable to receive professional bereavement support.