An evaluation of the neuroendocrine response to sleep in pediatric burn patients

Changes in brain function and heart sound in acute sleep deprivation individuals

AIMS

Sleep deprivation (SD) has become a health problem in modern society due to its adverse effects on different aspects. However, the relationship between sleep and cardiovascular system function remains unclear. Here we explored the changes occurring in the brain and the heart sounds after SD.

METHODS

Ninety healthy adult men were recruited and subjected to 36 h of Sleep Deprivation (SD). They participated in a number of tests, including measurements of the heart sound, blood oxygen, and heart rate every 2 h. By using of principal component analysis to reduced the dimensionality of heart sound data. While the ALFF and ReHo indexes were measured via fMRI before and after SD. Correlation and regression analyses were used to reveal the relationship between fMRI and heart sound changes due to SD.

RESULTS

In this study, there were no abnormal values in the heart rate and blood oxygen during 36 h of SD, whereas the intensity of heart sounds fluctuated significantly increased and decreased. The ALFF was increased in bilateral pericalcarine(Calcarine), left anterior cuneus, (Precuneus_L), right superior temporal gyrus(Temporal_Sup_R), left supplementary motor area (Supp_Motor_Area_L); However, it was reduced in the right medial superior frontal gyrus (Frontal_Sup_Medial_R), right dorsolateral superior frontal gyrus (Frontal_Sup_R) and left medial frontal gyrus (Frontal_Mid_L). The regression analysis uncovered that the intensity of the heart sound in the systole, s1, and s2 phase could be explained by Calcarine_L changes.

CONCLUSION

Acute sleep deprivation affects cardiac-brain axis and the specific brain regions. Calcarine_L changes during sleep deprivation are involved in regulating heart contractions.

Pediatric Intensive Care Unit related Sleep and Circadian Dysregulation: a focused review

The pediatric intensive care unit (PICU) is bright, loud, and disruptive to children. Strategies to improve the sleep of adults in the ICU have improved delirium and mortality rates. Children need more sleep than adults for active growth, healing, and development when well; this is likely true when they are critically ill. This review was performed to describe what we know in this area to date with the intent to identify future directions for research in this field. Since the 1990s, 16 articles on 14 observational trials have been published investigating the sleep on a total of 312 critically ill children and the melatonin levels of an additional 144. Sleep measurements occurred in 9 studies through bedside observation (n = 2), actigraphy (n = 2), electroencephalogram (n = 1) and polysomnography (n = 4), of which polysomnography is the most reliable. Children in the PICU sleep more during the day, have fragmented sleep and disturbed sleep architecture. Melatonin levels may be elevated and peak later in critically ill children. Early data suggest there are at-risk subgroups for sleep and circadian disruption in the PICU including those with sepsis, burns, traumatic brain injury and after cardiothoracic surgery. The available literature describing the sleep of critically ill children is limited to small single-center observational studies with varying measurements of sleep and inconsistent findings. Future studies should use validated measurements and standardized definitions to begin to harmonize this area of medicine to build toward pragmatic interventional trials that may shift the paradigm of care in the pediatric intensive care unit.

Actigraphy in mechanically ventilated pediatric ICU patients: comparison to PSG and evaluation of behavioral circadian rhythmicity

Sleep disruption is common in pediatric intensive care unit (PICU) patients, but measuring sleep in this population is challenging. We aimed to evaluate the utility of actigraphy for estimating circadian rhythmicity in mechanically ventilated PICU patients and its accuracy for measuring sleep by comparing it to polysomnogram (PSG). We conducted a single-center prospective observational study of children 6 months - 17 years of age receiving mechanical ventilation and standard, protocolized sedation for acute respiratory failure, excluding children with acute or historical neurologic injury. We enrolled 16 children and monitored them with up to 14 days of actigraphy and 24 hours of simultaneous limited (10 channel) PSG. Daily actigraphy-based activity profiles demonstrated that patients had a high level of nighttime activity (30-41% of total activity), suggesting disrupted circadian activity cycles. Among n = 12 patients with sufficient actigraphy and PSG data overlap, actigraphy-based sleep estimation showed poor agreement with PSG-identified sleep states, with good sensitivity (94%) but poor specificity (28%), low accuracy (70%,) and low agreement (Cohen's kappa = 0.2, 95% CI = 0.08-0.31). Using univariate linear regression, we identified that Cornell Assessment of Pediatric Delirium scores were associated with accuracy of actigraphy but that other clinical factors including sedative medication doses, activity levels, and restraint use were not. In this population, actigraphy did not reliably discern between sleep and wake states. However, in select patients, actigraphy was able to distinguish diurnal variation in activity patterns, and therefore may be useful for evaluating patients' response to circadian-oriented interventions.

Objective Sleep Characteristics and Factors Associated With Sleep Duration and Waking During Pediatric Hospitalization

IMPORTANCE

Children's sleep may be affected by hospitalization, yet few objective determinations of sleep patterns are reported for children in intensive care or general medicine units. There is limited research on relationships between sleep in hospital and child (eg, age, pain), treatment (eg, medications, nurse presence), or environmental (eg, noise, light, type of unit) factors.

OBJECTIVE

To determine sleep quantity and patterns in hospitalized children and determine factors associated with sleep quantity and nighttime waking for children in hospital.

DESIGN, SETTING, AND PARTICIPANTS

This was a prospective cross-sectional study of children admitted to a general pediatric unit or a pediatric intensive care unit at a pediatric quaternary teaching hospital in Toronto, Ontario, Canada, from October 2007 to July 2008. Participants included children aged 1 to 18 years who were expected to stay in hospital for at least 2 nights. Demographic data, information about the hospital stay and illness, and usual sleep habits were collected. Children wore an actigraph for 1 to 3 consecutive days and nights and completed a sleep diary. Sound and light meters were placed at the bedside. Data analyses took place in April 2009.

MAIN OUTCOMES AND MEASURES

The primary outcome was the mean number of minutes of child nighttime sleep from 7:30 pm to 7:29 am. Sleep variables were averaged over days and nights recorded (mean [SD] days and nights of wear, 2.54 [0.71]) and examined for associations with sleep quantity and patterns, as well as hazard of waking in the night.

RESULTS

Of 124 eligible children approached for inclusion, 69 children consented (35 [51%] female; 20 [29%] aged 1-3 years, 10 [14%] aged 4-7 years, 17 [24%] aged 8-12 years, and 22 [32%] aged 13-18 years; 58 [84%] in the general pediatric unit). Children aged 1 to 3, 4 to 7, 8 to 12, and 13 to 18 years obtained a mean (SD) of 444 (132), 475 (86), 436 (114), and 384 (83) minutes of nighttime sleep, respectively; mean (SD) number of night awakenings was 14 (3), 18 (3), 14 (8), and 12 (6), respectively. Children on general pediatric units slept 258 minutes more per night than children sleeping in the pediatric intensive care unit (95% CI, 165.16-350.56 minutes; P < .001), children admitted for planned surgery slept 123 minutes more than children admitted for exacerbations of chronic illness (95% CI, 49.23-196.01 minutes; P < .01), and children sleeping in rooms with other patients slept 141 minutes fewer than children in private rooms (95% CI, -253.51 to -28.35 minutes; P = .01). Sound events greater than 80 dB were significantly associated with increased risk of instantaneous waking (hazard ratio [HR], 1.35; 95% CI, 1.02-1.80; P = .04), as were light events greater than 150 lux (HR, 1.17; 95% CI, 1.01-1.36; P = .03), receiving a medication that promoted sleep (HR, 1.04; 95% CI, 1.00-1.08; P = .03), and having a nurse in the room for most or all of the night (HR, 1.08; 95% CI, 1.03-1.13; P = .003). Sleeping on the general pediatrics unit was significantly associated with decreased risk of instantaneous waking (HR, 0.81; 95% CI, 0.77-0.85; P < .001), as was being admitted for planned surgery (HR, 0.95; 95% CI, 0.91-0.99; P = .04), receiving a medication that promoted wakefulness (HR, 0.96; 95% CI, 0.93-0.995; P = .02), and sharing a room with another patient (HR, 0.78; 95% CI, 0.72-0.84; P < .001).

CONCLUSIONS AND RELEVANCE

In this cross-sectional study of hospitalized children, children experienced considerable nighttime waking and sleep restriction to levels below national clinical recommendations at a time when they most needed the benefits of sleep. Given light and noise were the greatest contributors to nighttime waking in hospital, clinicians, administrators and hospital design experts should work together for solutions.

Dehydroepiandrosterone: a potential therapeutic agent in the treatment and rehabilitation of the traumatically injured patient

Severe injuries are the major cause of death in those aged under 40, mainly due to road traffic collisions. Endocrine, metabolic and immune pathways respond to limit the tissue damage sustained and initiate wound healing, repair and regeneration mechanisms. However, depending on age and sex, the response to injury and patient prognosis differ significantly. Glucocorticoids are catabolic and immunosuppressive and are produced as part of the stress response to injury leading to an intra-adrenal shift in steroid biosynthesis at the expense of the anabolic and immune enhancing steroid hormone dehydroepiandrosterone (DHEA) and its sulphated metabolite dehydroepiandrosterone sulphate (DHEAS). The balance of these steroids after injury appears to influence outcomes in injured humans, with high cortisol: DHEAS ratio associated with increased morbidity and mortality. Animal models of trauma, sepsis, wound healing, neuroprotection and burns have all shown a reduction in pro-inflammatory cytokines, improved survival and increased resistance to pathological challenges with DHEA supplementation. Human supplementation studies, which have focused on post-menopausal females, older adults, or adrenal insufficiency have shown that restoring the cortisol: DHEAS ratio improves wound healing, mood, bone remodelling and psychological well-being. Currently, there are no DHEA or DHEAS supplementation studies in trauma patients, but we review here the evidence for this potential therapeutic agent in the treatment and rehabilitation of the severely injured patient.

Sleep and Delirium in Pediatric Critical Illness: What Is the Relationship?

With growing recognition of pediatric delirium in pediatric critical illness there has also been increased investigation into improving recognition and determining potential risk factors. Disturbed sleep has been assumed to be one of the key risk factors leading to delirium and is commonplace in the pediatric critical care setting as the nature of intensive care requires frequent and invasive monitoring and interventions. However, this relationship between sleep and delirium in pediatric critical illness has not been definitively established and may, instead, reflect significant overlap in risk factors and consequences of underlying neurologic dysfunction. We aim to review the existing tools for evaluation of sleep and delirium in the pediatric critical care setting and review findings from recent investigations with application of these measures in the pediatric intensive care unit.

Sleep of critically ill children in the pediatric intensive care unit: a systematic review

Critically ill children in the pediatric intensive care unit (PICU) are exposed to multiple physical, environmental and pharmacologic factors which increase the propensity for sleep disruption and loss and may, in turn, play a role in short-term recovery from critical illness and long-term neurocognitive outcomes. Mechanically ventilated children receive sedative and analgesic medications, often at high doses and for long durations, to improve comfort and synchrony with mechanical ventilation. Sedatives and analgesics can decrease slow wave sleep and rapid eye movement sleep. Paradoxically, sedative medication doses are often increased in critically ill children to improve the subjective assessment of sedation and sleep, leading to further agitation and deterioration of sleep quality. The heterogeneity in age and critical illness encountered in the PICU pose several challenges to research on sleep in this setting. The present article reviews the available evidence on sleep in critically ill children admitted to the PICU, with an emphasis on subjective and objective methods of sleep assessment used and special populations studied, including mechanically ventilated children and children with severe burns.

Clinical assessment of sleep among pediatric burn patients does not correlate with polysomnography

A vast amount of sleep research relies on subjective, observational assessments of wakefulness and sleep. The authors had the unique opportunity to compare observational and polysomnographic (PSG) determinations of sleep in a randomized crossover study of sleep-inducing medication in a group of pediatric burn patients. Pediatric burn patients were randomized to one of two regimens with sleep-inducing agents over a 2-week period. PSG was conducted for three consecutive nights each week, between 7-13 and 14-20 days postburn. The first night of monitoring each week was conducted without medication to serve as a baseline. Observational sleep assessments (awake, drowsy, or asleep) were simultaneously recorded every 15 minutes. PSG concordance with observation was based on the PSG sleep stages identified during the 2 minutes before the observations. If all 30-second epochs in the two minutes were designated as sleep stage 1 or above, then the PSG record was categorized as asleep. If all epochs demonstrated wakefulness, an awake status was recorded. Otherwise, the corresponding PSG finding was classified as mixed. Forty patients were enrolled into the study, with a mean age of 9.4 ± 0.6 years, TBSA burn of 50.1 ± 2.9%, and third-degree burn surface area of 43.2 ± 3.6%. Patients were judged according to observational criteria to be awake 9% of the nocturnal study period compared with PSG recordings indicating that the patients were awake 52.3% of the time. The correlation between observation and PSG was poor regardless of sleep agent administration. In conclusion, observational determination of wakefulness in pediatric burn patients correlates poorly with PSG; therefore, PSG is vital in the accurate evaluation of sleep-inducing medications among burn patients.

The effect of ketamine administration on nocturnal sleep architecture

Substantial evidence exists in the acute, rehabilitative and outpatient settings demonstrating the presence of significant sleep pattern disturbances after burn injury. Although the etiology is multifactorial and includes environmental, injury, and treatment mediators, previous clinical studies have not analyzed the critically important relationship of various medications to sleep architecture. The purpose of this investigation was to describe the after-effect of ketamine on sleep patterns in seriously ill burn patients. Forty pediatric patients with a mean TBSA burn of 50.1 ± 2.9% (range, 22-89%) and full-thickness injury of 43.2 ± 3.6% (range, 24-89%) were enrolled in this sleep study. Twenty-three of the 40 patients received ketamine on the day of polysomnography testing. Standard polysomnographic sleep variables were measured from 10:00 pm until 7:00 am. Chi-square test and t-test were used for comparison of descriptive variables between the ketamine and nonketamine groups. A logarithmic transformation was used for analysis when necessary. Ketamine administration was associated with reduced rapid eye movement (REM) sleep when compared with patients who did not receive ketamine on the day of the sleep study (P < 0.04). Both ketamine and nonketamine groups were clearly REM deficient when compared with nonburn norms. There was no relationship between ketamine use and effect on nocturnal total sleep time, number of awakenings, or percent of time awake or in stage 1, 2, or 3 + 4 sleep. In conclusion, ketamine was associated with altered sleep architecture as evidenced by a reduction in REM sleep. This finding does not seem to be clinically significant when considering the magnitude of overall REM sleep pattern disturbance observed in both the ketamine and nonketamine groups compared with nonburn norms. Further research is required to identify potential mechanisms of disturbed sleep so that appropriate interventions can be developed.

Review of burn injury research for the year 2009

Research in burn care for the calendar year 2009 was robust and diverse with >1400 research articles published on a wide range of topics. In this review, the authors highlight some innovative and potentially impactful research related to the overall care of burn- injured patients. The authors grouped articles according to the following categories: critical care, infection, inhalation injury, epidemiology, psychology, wound characterization and treatment, nutrition and metabolism, pain and itch management, burn reconstruction, and rehabilitation. They found that the holistic nature of burn care is reflected in the diverse research performed in 2009 throughout the world and that this research has provided important evidence that has improved or will improve burn care overall.