Low melatonin excretion during mechanical ventilation in the intensive care unit

Disruption of the circadian rhythm of melatonin: A biomarker of critical illness severity

Circadian dysrhythmias occur commonly in critically ill patients reflecting variable effects of underlying illness, ICU environment, and treatments. We retrospectively analyzed the relationship between clinical outcomes and 24-h urinary 6-sulfatoxymelatonin (aMT6s) excretion profiles in 37 critically ill patients with shock and/or respiratory failure. Nonlinear regression was used to fit a 24-h cosine curve to each patient's aMT6s profile, with rhythmicity determined by the zero-amplitude test. From these curves we determined acrophase, amplitude, phase, and night/day ratio. After assessing unadjusted relationships, we identified the optimal multivariate models for hospital survival and for discharge to home (vs. death or transfer to another facility). Normalized aMT6s rhythm amplitude was greater (p = 0.005) in patients discharged home than in those who were not, while both groups exhibited a phase delay. Patients with rhythmic aMT6s excretion were more likely to survive (OR 5.25) and be discharged home (OR 8.89; p < 0.05 for both) than patients with arrhythmic profiles, associations that persisted in multivariate modelling. In critically ill patients with shock and/or respiratory failure, arrhythmic and/or low amplitude 24-h aMT6s rhythms were associated with worse clinical outcomes, suggesting a role for the melatonin-based rhythm as a novel biomarker of critical illness severity.

Preventing and treating delirium in clinical settings for older adults

Delirium is a serious consequence of many acute or worsening chronic medical conditions, a side effect of medications, and a precipitant of worsening functional and cognitive status in older adults. It is a syndrome characterized by fluctuations in cognition and impaired attention that develops over a short period of time in response to an underlying medical condition, a substance (prescribed, over the counter, or recreational), or substance withdrawal and can be multi-factorial. We present a narrative review of the literature on nonpharmacologic and pharmacologic approaches to prevention and treatment of delirium with a focus on older adults as a vulnerable population. Older adult patients are most at risk due to decreasing physiologic reserves, with delirium rates of up to 80% in critical care settings. Presentation of delirium can be hyperactive, hypoactive, or mixed, making identification and study challenging as patients with hypoactive delirium are less likely to come to attention in an inpatient or long-term care setting. Studies of delirium focus on prevention and treatment with nonpharmacological or medication interventions, with the preponderance of evidence favoring multi-component nonpharmacological approaches to prevention as the most effective. Though use of antipsychotic medication in delirium is common, existing evidence does not support routine use, showing no clear benefit in clinically significant outcome measures and with evidence of harm in some studies. We therefore suggest that antipsychotics be used to treat agitation, psychosis, and distress associated with delirium at the lowest effective doses and shortest possible duration and not be considered a treatment of delirium itself. Future studies may clarify the use of other agents, such as melatonin and melatonin receptor agonists, alpha-2 receptor agonists, and anti-epileptics.

Causes, Consequences, and Treatments of Sleep and Circadian Disruption in the ICU: An Official American Thoracic Society Research Statement

Background: Sleep and circadian disruption (SCD) is common and severe in the ICU. On the basis of rigorous evidence in non-ICU populations and emerging evidence in ICU populations, SCD is likely to have a profound negative impact on patient outcomes. Thus, it is urgent that we establish research priorities to advance understanding of ICU SCD. Methods: We convened a multidisciplinary group with relevant expertise to participate in an American Thoracic Society Workshop. Workshop objectives included identifying ICU SCD subtopics of interest, key knowledge gaps, and research priorities. Members attended remote sessions from March to November 2021. Recorded presentations were prepared and viewed by members before Workshop sessions. Workshop discussion focused on key gaps and related research priorities. The priorities listed herein were selected on the basis of rank as established by a series of anonymous surveys. Results: We identified the following research priorities: establish an ICU SCD definition, further develop rigorous and feasible ICU SCD measures, test associations between ICU SCD domains and outcomes, promote the inclusion of mechanistic and patient-centered outcomes within large clinical studies, leverage implementation science strategies to maximize intervention fidelity and sustainability, and collaborate among investigators to harmonize methods and promote multisite investigation. Conclusions: ICU SCD is a complex and compelling potential target for improving ICU outcomes. Given the influence on all other research priorities, further development of rigorous, feasible ICU SCD measurement is a key next step in advancing the field.

Sleep in the intensive care unit

PURPOSE OF REVIEW

Sleep is particularly important for critically ill patients. Here, we review the latest evidence on how sleep and circadian disruption in the intensive care unit (ICU) affects physiology and clinical outcomes, as well as the most recent advances in sleep and circadian rhythm promoting interventions including therapeutics.

RECENT FINDINGS

On a molecular level, clock genes dysrhythmia and altered immunity are clearly linked, particularly in sepsis. Melatonin may also be associated with insulin sensitivity in ICU patients. Clinically, changes in sleep architecture are associated with delirium, and sleep-promoting interventions in the form of multifaceted care bundles may reduce its incidence. Regarding medications, one recent randomized controlled trial (RCT) on melatonin showed no difference in sleep quality or incidence of delirium.

SUMMARY

Further investigation is needed to establish the clinical relevance of sleep and circadian disruption in the ICU. For interventions, standardized protocols of sleep promotion bundles require validation by larger multicenter trials. Administratively, such protocols should be individualized to both organizational and independent patient needs. Incorporating pharmacotherapy such as melatonin and nocturnal dexmedetomidine requires further evaluation in large RCTs.

Temperature Profile and Adverse Outcomes After Discharge From the Intensive Care Unit

BACKGROUND

A predictive model that uses the rhythmicity of core body temperature (CBT) could be an easily accessible clinical tool to ultimately improve outcomes among critically ill patients.

OBJECTIVES

To assess the relation between the 24-hour CBT profile (CBT-24) before intensive care unit (ICU) discharge and clinical events in the step-down unit within 7 days of ICU discharge.

METHODS

This retrospective cohort study in a tertiary ICU at a single center included adult patients requiring acute invasive ventilation for more than 48 hours and assessed major clinical adverse events (MCAEs) and rapid response system activations (RRSAs) within 7 days of ICU discharge (MCAE-7 and RRSA-7, respectively).

RESULTS

The 291 enrolled patients had a median mechanical ventilation duration of 139 hours (IQR, 50-862 hours) and at admission had a median Acute Physiology and Chronic Health Evaluation II score of 22 (IQR, 7-42). At least 1 MCAE or RRSA occurred in 64% and 22% of patients, respectively. Independent predictors of an MCAE-7 were absence of CBT-24 rhythmicity (odds ratio, 1.78 [95% CI, 1.07-2.98]; P = .03), Sequential Organ Failure Assessment score at ICU discharge (1.10 [1.00-1.21]; P = .05), male sex (1.72 [1.04-2.86]; P = .04), age (1.02 [1.00-1.04]; P = .02), and Charlson Comorbidity Index (0.87 [0.76-0.99]; P = .03). Age (1.03 [1.01-1.05]; P = .006), sepsis at ICU admission (2.02 [1.13-3.63]; P = .02), and Charlson Comorbidity Index (1.18 [1.02-1.36]; P = .02) were independent predictors of an RRSA-7.

CONCLUSIONS

Use of CBT-24 rhythmicity can assist in stratifying a patient's risk of subsequent deterioration during general care within 7 days of ICU discharge.

Development and Implementation of a Multicomponent Protocol to Promote Sleep and Reduce Delirium in a Medical Intensive Care Unit

BACKGROUND

Evidence suggests that poor sleep increases risk of delirium. Because delirium is associated with poor outcomes, institutions have developed protocols to improve sleep in critically ill patients.

OBJECTIVE

To assess the impact of implementing a multicomponent sleep protocol.

METHODS

In this prospective, preimplementation and postimplementation evaluation, adult patients admitted to the medical intensive care unit (ICU) over 42 days were included. Outcomes evaluated included median delirium-free days, median Richards-Campbell Sleep Questionnaire (RCSQ) score, median optimal sleep nights, duration of mechanical ventilation (MV), ICU and hospital length of stay (LOS), and in-hospital mortality.

RESULTS

The preimplementation group included 78 patients and postimplementation group, 84 patients. There was no difference in median delirium-free days (1 day [interquartile range, IQR, = 0-2.5] vs 1 day [IQR = 0-2]; P = 0.48), median RCSQ score (59.4 [IQR = 43.2-71.6] vs 61.2 [IQR = 49.9-75.5]; P = 0.20), median optimal sleep nights (1 night [IQR = 0-2] vs 1 night [IQR = 0-2]; P = 0.95), and in-hospital mortality (16.7% vs 17.9%, P = 1.00). Duration of MV (8 days [IQR = 4-10] vs 4 days [IQR = 2-7]; P = 0.03) and hospital LOS (13 days [IQR = 7-22.3] vs 8 days [IQR = 6-17]; P = 0.05) were shorter in the postimplementation group, but both were similar between groups after adjusting for age and severity of illness.

CONCLUSIONS AND RELEVANCE

This report demonstrates that implementation of a multicomponent sleep protocol in everyday ICU care is feasible, but limitations exist when evaluating impact on measurable outcomes. Additional evaluations are needed to identify the most meaningful interventions and best practices for quantifying impact on patient outcomes.

A pilot study on the melatonin treatment in patients with early septic shock: results of a single-center randomized controlled trial

BACKGROUND

We assessed the potential impact of a high dose of melatonin treatment in patients with early septic shock.

METHODS

Forty patients with early septic shock were randomly allocated to the melatonin or placebo groups. Besides standard-of-care treatment, melatonin and placebo were administered at a dose of 50 mg for five consecutive nights. The efficacy outcomes were severity of organ dysfunction based on the Sequential Organ Failure Assessment (SOFA) score, the number of patients requiring mechanical ventilation and ventilator-free days, the mean required vasopressor dose and vasopressor-free days, and 28 days all-cause mortality.

RESULTS

After 5-day treatment, the mean SOFA scores decreased 4.05 ± 4.75 score in the melatonin group and 2.25 ± 4.87 in the placebo group. On day 28, 60% of the melatonin-treated patients and 35% of the placebo-treated patients had a SOFA score below six. Thirteen cases in the placebo group and nine cases in the melatonin group required mechanical ventilation; however, there was no statistically significant difference between the groups regarding these outcomes. The melatonin-treated patients had more ventilator-free days than placebo-treated patients over the 28-day (16.90 ± 9.24 vs. 10.00 ± 10.94; p value = 0.035). The mean reduction in the required dose of vasopressor was 6.2 ± 5.12 in the melatonin-treated patients compared to 3.20 ± 3.95 in the placebo-treated patients (p value = 0.045). Vasopressor-free days in the melatonin-treated group were also significantly more than the placebo-treated group (12.75 ± 7.43 days vs. 10.15 ± 6.12 days; p value = 0.046).

CONCLUSIONS

Our pilot study supported the potential benefits of melatonin in treating septic shock. Further clinical evidence is required for expanding and confirming these findings.

TRIAL REGISTRATION

The trial was registered at Clinicaltrials.gov (ID code: IRCT20120215009014N296). Registration date: 15/09/2019.

Light Levels in ICU Patient Rooms: Dimming of Daytime Light in Occupied Rooms

One-third of patients report disruption of sleep by overnight light. Importantly, light causes both immediate sleep disturbance and influences circadian function, a fundamental process underpinning high-quality sleep. Short bursts of light at night and/or lack of bright daytime light disrupt circadian alignment, leading to sleep deficiency. To improve understanding of 24-hour light patterns, we conducted a longitudinal study of light levels in intensive care unit (ICU) rooms. Over 450 room-days, we observed high variability, dim daytime light, and active dimming of natural sunlight in occupied rooms. Such noncircadian light patterns have multifactorial influences on sleep and are a key target for sleep improvement in the ICU.

The Nexus Between Sleep Disturbance and Delirium Among Intensive Care Patients

Sleep in intensive care is hampered due to many factors; the clinical environment itself exacerbates sleep disturbance. Research suggests that interventions aimed at improving sleep quality have produced positive effects in reducing incidences and duration of delirium. Sleep disturbance is well documented among intensive care patients; however, its prognostic impact is not fully understood. Delirium, disproportionally prevalent among intensive care patients, has significant prognostic factors related to patient outcomes, in which sleep disturbance often is present. The relationship between sleep disturbance and delirium is complex, sharing commonalities in relation to neurobiological and neurohormonal alterations, which may contribute to a bidirectional relationship.

Temperature rhythms and ICU sleep: the TRIS study

BACKGROUND

Core body temperature (CBT) patterns associated with sleep have not been described in the critically ill. This study aimed to characterize night-time sleep and its relationship to CBT in ICU patients.

METHODS

A prospective study was performed in a 27-bed tertiary adult intensive care unit of 20 mechanically ventilated patients in the weaning stage of their critical illness. The study assessed sleep by polysomnography (PSG) during the evening between 21:00-7:00 hours, nursing interventions using the Therapeutic Intervention Scoring System (TISS), illness severity using SOFA and APACHE II scores and CBT 24-hour pattern.

RESULTS

Patients were awake for approximately half the study period (45.04%, IQR 13.81-77-17) with no REM (0%, IQR 0-0.04%) and median arousals of 19.5/hour (IQR 7.1-40.9). The 24-hour CBT had a rhythmic pattern in 13 (65%) patients with a highly variable phase of median peak time at 17:35 hours (IQR 12:40-19:39). No significant associations were found between CBT rhythmicity, sleep stages, sleep EEG frequency density, illness severity scores or TISS on the day of PSG. There was no relationship between time awake and CBT rhythmicity (P=0.48) or CBT peak time (P=0.82). The relationship between circadian rhythms and sleep patterns in the critically ill is complex.

CONCLUSIONS

Patients recovering in ICU commonly have CBT loss of rhythmicity or a significant phase shift with loss of normal night-time patterns of sleep architecture. Appropriate care plans to promote sleep and circadian rhythm require further investigation of contributing factors such as environment, clinical care routines, illness type and severity.

Circadian rhythm in critically ill patients: Insights from the eICU Database

Objective

To investigate the circadian variation among critically ill patients and its association with clinical characteristics and survival to hospital discharge in a large population of patients in the intensive care unit (ICU).

Methods

Circadian variation was analyzed by fitting cosinor models to hourly blood pressure (BP) measurements in patients of the eICU Collaborative Research Database with an ICU length of stay of at least 3 days. We calculated the amplitude of the 24-hour circadian rhythm and time of the day when BP peaked. We determined the association between amplitude and time of peak BP and severity of illness, medications, mechanical intubation, and survival to hospital discharge.

Results

Among 23,355 patients (mean age 65 years, 55% male), the mean amplitude of the 24-hour rhythm was 4.5 ± 3.1 mm Hg. Higher APACHE-IV scores, sepsis, organ dysfunction, and mechanical ventilation were associated with a lower amplitude and a shifted circadian rhythm (P < .05 for all). The timing of the BP peak was associated with in-hospital mortality (P < .001). Higher BP amplitude was associated with shorter ICU (2 mm Hg amplitude: 7.0 days, 8 mm Hg amplitude: 6.7 days) and hospital (2 mm Hg amplitude: 11.8 days, 8 mm Hg amplitude: 11.3 days) lengths of stay and lower in-hospital mortality (2 mm Hg amplitude: 18.2%, 8 mm Hg amplitude: 15.2%) (P < .001 for all).

Conclusion

The 24-hour rhythm is dampened and phase-shifted in sicker patients and those on mechanical ventilation, vasopressors, or inotropes. Dampening and phase shifting are associated with a longer length of stay and higher in-hospital mortality.

Serum melatonin concentration in critically ill patients randomized to sedation or non-sedation

Background

Abolished circadian rhythm is associated with altered cognitive function, delirium, and as a result increased mortality in critically ill patients, especially in those who are mechanically ventilated. The causes are multifactorial, of which changes in circadian rhythmicity may play a role. Melatonin plays a crucial role as part of the circadian and sleep/wake cycle. Whether sedation effects circadian regulation is unknown. Hence, the objective of this study was to evaluate the melatonin concentration in critically ill patients randomized to sedation or non-sedation and to investigate the correlation with delirium.

Methods

All patients were included and randomized at the intensive care unit at the hospital of southwest Jutland, Denmark. Seventy-nine patients completed the study (41 sedated and 38 non-sedated). S-melatonin was measured 3 times per day, (03.00, 14.00, and 22.00), for 4 consecutive days in total, starting on the second day upon randomization/intubation. The study was conducted as a sub-study to the NON-SEDA study in which one hundred consecutive patients were randomized to sedation or non-sedation with a daily wake-up call (50 in each arm). Primary outcome: melatonin concentration in sedated vs. non-sedated patients (analyzed using linear regression). Secondary outcome: risk of developing delirium or non-medically induced (NMI) coma in sedated vs. non-sedated patients, assessed by CAM-ICU (Confusion Assessment Method for the Intensive Care Unit) analyzed using logistic regression.

Results

Melatonin concentration was suppressed in sedated patients compared to the non-sedated. All patients experienced an elevated peak melatonin level early on in the course of their critical illness (p = 0.01). The risk of delirium or coma (NMI) was significantly lower in the non-sedated group (OR 0.42 CI 0.27; 0.66 p < 0.0001). No significant relationship between delirium development and suppressed melatonin concentration was established in this study (OR 1.004 p = 0.29 95% CI 0.997; 1.010).

Conclusion

Melatonin concentration was suppressed in sedated, critically ill patients, when compared to non-sedated controls and the frequency of delirium was elevated in sedated patients.

Trail registration Clinicaltrials.gov (NCT01967680) on October 23, 2013.

Total Daily Production and Periodicity of Melatonin Metabolite in Critically Ill Children

OBJECTIVES

To determine whether total daily 6-sulfatoxymelatonin excretion and diurnal variation of melatonin secretion was maintained during the early phase of PICU admission through examination of the melatonin urinary metabolite, 6-sulfatoxymelatonin.

DESIGN

Exploratory prospective, observational study.

SETTING

Twelve-bed medical-surgical PICU of a Children's Hospital.

PATIENTS

Fifty children 3 months to 18 years old enrolled within 24 hours of PICU admission with access for urinary sampling.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Urine samples were collected at 4-hour intervals for 24 hours and stored at -80C. 6-sulfatoxymelatonin was determined in duplicate by direct enzyme-linked immunosorbent assay. Patients were heterogeneous for diagnosis, had a mean age of 8.1 years (SD = 6.1 yr), and median (interquartile range) Pediatric Risk of Mortality III of 10 (4-13). Mean (SD) total daily 6-sulfatoxymelatonin production was 30.0 µg (25.6 µg) for the first 24 hours, which did not differ significantly from the means on days 2 (p = 0.56) or 3 (p = 0.29), and was similar to literature controls. Mean 6-sulfatoxymelatonin production for the population fit a periodic function well, with a reliable amplitude of 326 ng/hr and peak excretion from 04:00 to 08:00 (F = 4.4, p = 0.01), even when 6-sulfatoxymelatonin was corrected for body weight (F = 3.4, p = 0.03) and when sedation was included in the model (F = 3.95, p = 0.004). There was no significant correlation between lighting and 6-sulfatoxymelatonin excretion at any time period (R values: 0.11-0.25, p = 0.10-0.94). Mean 6-sulfatoxymelatonin excretion did not fit the model for a periodic function well for the subpopulations studied (sepsis [n = 18, F = 1.1, p = 0.32], respiratory failure requiring deep sedation [n = 10, F = 0.4, p = 0.66], and neurologic injury [n = 7, F = 0.6, p = 0.55]).

CONCLUSIONS

Total daily and diurnal variation of 6-sulfatoxymelatonin excretion is heterogeneously maintained early in pediatric critical illness. However, this may not hold true for specific diagnostic categories.

Effect of Exogenous Melatonin Administration in Critically Ill Patients on Delirium and Sleep: A Randomized Controlled Trial

Introduction

Sleep deprivation is a contributor for delirium in intensive care. Melatonin has been proposed as a pharmacological strategy to improve sleep, but studies have shown that the increase in plasma levels of melatonin do not correlate to a beneficial clinical effect; in addition, melatonin's short half-life may be a major limitation to achieving therapeutic levels. This study applies a previously published novel regimen of melatonin with proven sustained levels of melatonin during a 12 h period. In this study, the aim is to determine if such melatonin dosing positively influences on the sleep architecture and the incidence of delirium in intensive care.

Methods

Single center, randomized control trial with consecutive recruitment over 5 years. Medical and surgical patients were in a recovery phase, all weaning from mechanical ventilation. Randomized allocation to placebo or enteral melatonin, using a previously described regimen (loading dose of 3 mg at 21 h, followed by 0.5 mg hourly maintenance dose until 03am through a nasogastric tube). Sleep recordings were performed using polysomnogram at baseline (prior to intervention) and the third night on melatonin (postintervention recording). Delirium was assessed using the Richmond Agitation and the Confusion Assessment Method Scales. Environmental light and noise levels were recorded using a luxmeter and sound meter.

Results

80 patients were screened, but 33 were recruited. Sleep studies showed no statistical differences on arousal index or length of sleep. Baseline delirium scores showed no difference between groups when compared to postintervention scores. RASS scores were 1 in both groups at baseline, compared to zero (drug group) and 0.5 (placebo group) posttreatment. CAM scores were zero (drug group) and 1 (placebo group) at baseline, compared to zero (in both groups) postintervention.

Conclusion

High levels of plasma melatonin during the overnight period of intensive care cohort patients did not improve sleep nor decreased the prevalence of delirium. This trial is registered with Anzctr.org.au/ACTRN12620000661976.aspx.

The effect of melatonin on reduction in the need for sedative agents and duration of mechanical ventilation in traumatic intracranial hemorrhage patients: a randomized controlled trial

Purpose

This study aimed to determine the effect of exogenous melatonin on the number of sedative drugs and the duration of mechanical ventilation in traumatic intracranial hemorrhage patients in ICU.

Methods

This double-blind randomized clinical trial study was conducted in the ICU wards of Golestan Hospital, Ahvaz, Iran, from September 2017 to March 2018. In this study, 52 patients with intracerebral hemorrhage were selected by convenient sampling (26 patients in each group) and were randomly assigned to two groups of melatonin and control. Sedation and pain management package was applied to both groups. Outcomes: Amount of the sedative and opioid drug; mechanical ventilation time; ICU staying time; Glasgow Coma Score; hemodynamic parameters.

Results

There was no significant difference between them in terms of demographic characteristics. Cumulative doses of morphine and mechanical ventilation time were significant in two groups. (P < 0.05) The mean length of ICU staying was not significant. Glasgow Coma Score on the 6th day was significant in two groups (P < 0.05). Diastolic blood pressure was significant between groups (P < 0.001).

Conclusion

This study presented that morphine consumption and mechanical ventilation time were significantly lower in the melatonin group than in the control. Also, rise in GCS in the melatonin group was faster in the melatonin group than in the control. The use of melatonin can be recommended for patients with ICH in the ICU for better outcomes.

Melatonin in Critical Care

Melatonin is involved in regulation of a variety of physiologic functions, including circadian rhythm, reproduction, mood, and immune function. Exogenous melatonin has demonstrated many clinical effects. Numerous clinical studies have documented improved sleep quality following administration of exogenous melatonin. Recent studies also demonstrate the analgesic, anxiolytic, antiinflammatory, and antioxidative effects of melatonin. This article reviews the principal properties of melatonin and how these could find clinical applications in care of the critically ill patients.

The Effects of Naturalistic Light on Diurnal Plasma Melatonin and Serum Cortisol Levels in Stroke Patients during Admission for Rehabilitation: A Randomized Controlled Trial

Background: Stroke patients admitted for rehabilitation often lack sufficient daytime blue light exposure due to the absence of natural light and are often exposed to light at unnatural time points. We hypothesized that artificial light imitating daylight, termed naturalistic light, would stabilize the circadian rhythm of plasma melatonin and serum cortisol levels among long-term hospitalized stroke patients. Methods: A quasi-randomized controlled trial. Stroke patients in need of rehabilitation were randomized between May 1, 2014, and June 1, 2015 to either a rehabilitation unit equipped entirely with always on naturalistic lighting (IU), or to a rehabilitation unit with standard indoor lighting (CU). At both inclusion and discharge after a hospital stay of at least 2 weeks, plasma melatonin and serum cortisol levels were measured every 4 hours over a 24-hour period. Circadian rhythm was estimated using cosinor analysis, and variance between time-points. Results: A total of 43 were able to participate in the blood collection. Normal diurnal rhythm of melatonin was disrupted at both inclusion and discharge. In the IU group, melatonin plasma levels were increased at discharge compared to inclusion (n = 23; median diff, 2.9; IQR: -1.0 to 9.9, p = 0.030) and rhythmicity evolved (n = 23; p = 0.007). In the CU group, melatonin plasma levels were similar between discharge and inclusion and no rhythmicity evolved. Overall, both patient groups showed normal cortisol diurnal rhythms at both inclusion and discharge. Conclusions: This study is the first to demonstrate elevated melatonin plasma levels and evolved rhythmicity due to stimulation with naturalistic light.

Melatonin and cortisol exhibit different circadian rhythm profiles during septic shock depending on timing of onset: a prospective observational study

Background

Septic shock has been found to disrupt circadian rhythms. Moreover, timing of onset has been associated with different circadian profiles in experimental studies.

Results

In this prospective study, we enrolled 26 patients divided into two groups: Group A (N = 15) included subjects who had septic shock at the time of ICU admission and Group B (N = 11) included patients who developed septic shock during ICU admission. 6-Sulfatoxymelatonin (aMT6s) and cortisol levels were measured in urine samples every 4 h over a 24-h period. Two sets of samples were taken from Group A (entry/septic shock and exit) and three sets from Group B (entry, septic shock and exit). Mean, amplitude that is the difference between peak and mean values, as well as peak time, were estimated for both aMT6s and cortisol. In Group A, amplitude of aMT6s upon entry (septic shock) was reduced in relation to exit (437.2 ± 309.2 vs. 674.1 ± 657.6 ng/4 h, p < 0.05). Peak time occurred earlier (10:00 p.m. vs. 07:00 a.m, p < 0.05) and correlated with higher APACHE II score and longer ICU stay. In Group B, aMT6s mean values were significantly increased during septic shock (2492.2 ± 1709.1 ng/4 h) compared to both entry (895.4 ± 715.5 ng/4 h) and exit (1308.6 ± 1214.4 ng/4 h, p < 0.05 for all comparisons). Amplitude of aMT6s was also elevated during septic shock (794.8 ± 431.8 ng/4 h) in relation to entry (293.1 ± 275.9 ng/4 h, p < 0.05). Regarding cortisol rhythm in Group A, during septic shock amplitude was increased compared to exit (13.3 ± 31 ng/4 h vs. 8.7 ± 21.2 ng/4 h p < 0.05) and correlated with reduced hospital length of stay. In Group B, cortisol mean values and amplitude during septic shock (10 ± 5.3 and 3 ± 1.8 ng/4 h, respectively) were significantly reduced compared to both entry (30 ± 57.9 and 12.3 ± 27.3 ng/4 h) and exit (14.4 ± 20.7 and 6.6 ± 8.7 ng/4 h, p < 0.05 for all comparisons) and correlated with higher SOFA score and longer ICU and hospital stay.

Conclusions

Septic shock induced inverse changes of aMT6s and cortisol circadian rhythm profiles both within and between different groups of patients, depending on timing of onset. Reduced rhythmicity was correlated with severity of disease and longer ICU stay.

Feeding mitochondria: Potential role of nutritional components to improve critical illness convalescence

Persistent physical impairment is frequently encountered after critical illness. Recent data point towards mitochondrial dysfunction as an important determinant of this phenomenon. This narrative review provides a comprehensive overview of the present knowledge of mitochondrial function during and after critical illness and the role and potential therapeutic applications of specific micronutrients to restore mitochondrial function. Increased lactate levels and decreased mitochondrial ATP-production are common findings during critical illness and considered to be associated with decreased activity of muscle mitochondrial complexes in the electron transfer system. Adequate nutrient levels are essential for mitochondrial function as several specific micronutrients play crucial roles in energy metabolism and ATP-production. We have addressed the role of B vitamins, ascorbic acid, α-tocopherol, selenium, zinc, coenzyme Q10, caffeine, melatonin, carnitine, nitrate, lipoic acid and taurine in mitochondrial function. B vitamins and lipoic acid are essential in the tricarboxylic acid cycle, while selenium, α-tocopherol, Coenzyme Q10, caffeine, and melatonin are suggested to boost the electron transfer system function. Carnitine is essential for fatty acid beta-oxidation. Selenium is involved in mitochondrial biogenesis. Notwithstanding the documented importance of several nutritional components for optimal mitochondrial function, at present, there are no studies providing directions for optimal requirements during or after critical illness although deficiencies of these specific micronutrients involved in mitochondrial metabolism are common. Considering the interplay between these specific micronutrients, future research should pay more attention to their combined supply to provide guidance for use in clinical practise. REVISION NUMBER: YCLNU-D-17-01092R2.

Looking for light in the din: An examination of the circadian-disrupting properties of a medical intensive care unit

OBJECTIVE

Critically ill patients exhibit profound disturbances of circadian rhythmicity, most commonly in the form of a phase delay. We investigated the specific zeitgeber properties of a medical intensive care unit to develop a model that explained these abnormalities.

RESEARCH METHODOLOGY

Prospective, observational study conducted during 2013-2014. Twenty-four-hour ambient light (lux, 672 hours) and sound pressure levels (dBA, 504 hours) were measured in patient rooms. Patients and families were surveyed regarding their perceptions of the environment.

SETTING

University-based adult medical intensive care unit.

MAIN OUTCOME MEASURES

The timing and intensity of the ambient light-dark cycle and sound environment and the relationship of these measurements to patient/family perceptions.

RESULTS

Twenty-four-hour light-dark cycles were extremely weak and phase delayed relative to the solar cycle. Morning light averaged 12.1 (4.8, 37.2) lux, when only 24.9% ± 10.9% of available light was utilised; yet patients and families did not identify low daytime light levels as problematic. Median noise levels were invariably excessive (nighttime 47.9 [45.0, 51.3] dBA) with minimal variation, consistent with the absence of a defined rest period.

CONCLUSION

The intensive care unit functions as a near-constant routine protocol disconnected from solar time. Behavioural interventions to promote entrainment should be supported by objective measurements of light and sound.

Melatonin Secretion Is Increased in Children with Severe Traumatic Brain Injury

BACKGROUND

Traumatic brain injury (TBI) is a leading cause of death and disability in children. Oxidative stress plays a significant role in brain damage and melatonin exhibits both direct and indirect antioxidant effects. The primary aim of the present study was to evaluate serum melatonin levels in children with severe TBI in comparison to critically ill children admitted to the Pediatric Intensive Care Unit for conditions other than TBI.

METHODS

Twenty-four children were evaluated, equally divided into severe TBI and no-TBI. Blood samples for serum melatonin analysis were collected at 22:00, 01:00, 03:00, 05:00, 08:00, and 12:00.

RESULTS

Mean serum melatonin peaks in children of the TBI group were higher compared to the values of no-TBI critically ill children (495 ± 102 vs. 294 ± 119 pg/mL, p = 0.0002). Furthermore, the difference was even more significant in comparison to values reported in literature for healthy age-matched children (495 ± 102 vs. 197 ± 71 pg/mL, p < 0.0001).

CONCLUSION

This study has shown that endogenous serum melatonin levels dramatically increase in children after severe TBI. This elevation is likely to represent a response to oxidative stress and/or inflammation due to severe head injury.

Melatonin Secretion Pattern in Critically Ill Patients: A Pilot Descriptive Study

Critically ill patients have abnormal circadian and sleep homeostasis. This may be associated with higher morbidity and mortality. The aims of this pilot study were (1) to describe melatonin secretion in conscious critically ill mechanically ventilated patients and (2) to describe whether melatonin secretion and sleep patterns differed in these patients with and without remifentanil infusion. Eight patients were included. Blood-melatonin was taken every 4th hour, and polysomnography was carried out continually during a 48-hour period. American Academy of Sleep Medicine criteria were used for sleep scoring if sleep patterns were identified; otherwise, Watson's classification was applied. As remifentanil was periodically administered during the study, its effect on melatonin and sleep was assessed. Melatonin secretion in these patients followed a phase-delayed diurnal curve. We did not observe any effect of remifentanil on melatonin secretion. We found that the risk of atypical sleep compared to normal sleep was significantly lower (p < 0.001) under remifentanil infusion. Rapid Eye Movement (REM) sleep was only observed during the nonsedation period. We found preserved diurnal pattern of melatonin secretion in these patients. Remifentanil did not affect melatonin secretion but was associated with lower risk of atypical sleep pattern. REM sleep was only registered during the period of nonsedation.

Melatonin Pharmacological Blood Levels Increase Total Antioxidant Capacity in Critically Ill Patients

In this study, the aim was to test the biochemical effects of melatonin supplementation in Intensive Care Unit (ICU) patients, since their blood levels are decreased. Sixty-four patients were enrolled in the study. From the evening of the 3rd ICU day, patients were randomized to receive oral melatonin (3 mg, group M) or placebo (group P) twice daily, at 20:00 and 24:00, until discharged. Blood was taken (at 00:00 and 14:00), on the 3rd ICU day to assess basal nocturnal melatonin values, and then during the treatment period on the 4th and 8th ICU days. Melatonin, total antioxidant capacity, and oxidative stress were evaluated in serum. Melatonin circadian rhythm before treatment was similar in the two groups, with a partial preservation of the cycle. Four hours from the 1st administration (4th ICU day, 00:00), melatonin levels increased to 2514 (982.3; 7148) pg·mL⁻¹ in group M vs. 20.3 (14.7; 62.3) pg·mL⁻¹ in group P (p < 0.001). After five treatment days (8th ICU day), melatonin absorption showed a repetitive trend in group M, while in group P nocturnal secretion (00:00) was impaired: 20 (11.5; 34.5) pg·mL⁻¹ vs. 33.8 (25.0; 62.2) on the 3rd day (p = 0.029). Immediately from the beginning of treatment, the total antioxidant capacity was significantly higher in melatonin treated subjects at 00:00; a significant correlation was found between total antioxidant capacity and blood melatonin values (ρ = 0.328; p < 0.001). The proposed enteral administration protocol was adequate, even in the early phase, to enhance melatonin blood levels and to protect the patients from oxidative stress. The antioxidant effect of melatonin could play a meaningful role in the care and well-being of these patients.

The significance of circadian rhythms and dysrhythmias in critical illness

Many physiological and cellular processes cycle with time, with the period between one peak and the next being roughly equal to 24 h. These circadian rhythms underlie 'permissive homeostasis', whereby anticipation of periods of increased energy demand or stress may enhance the function of individual cells, organ systems or whole organisms. Many physiological variables related to survival during critical illness have a circadian rhythm, including the sleep/wake cycle, haemodynamic and respiratory indices, immunity and coagulation, but their clinical significance remains underappreciated. Critically ill patients suffer from circadian dysrhythmia, manifesting overtly as sleep disturbance and delirium, but with widespread covert effects on cellular and organ function. Environmental and pharmacological strategies that ameliorate or prevent circadian dysrhythmia have demonstrated clinical benefit. Harnessing these important biological phenomena to match metabolic supply to demand and bolster cell defenses at the apposite time may be a future therapeutic strategy in the intensive care unit.

Sleep quality and circadian rhythm disruption in the intensive care unit: a review

Sleep and circadian rhythm are reported to be severely abnormal in critically ill patients. Disturbed sleep can lead to the development of delirium and, as a result, can be associated with prolonged stay in the intensive care unit (ICU) and increased mortality. The standard criterion method of sleep assessment, polysomnography (PSG), is complicated in critically ill patients due to the practical challenges and interpretation difficulties. Several PSG sleep studies in the ICU reported the absence of normal sleep characteristics in many critically ill patients, making the standard method of sleep scoring insufficient in this patient group. Watson et al proposed a modified classification for sleep scoring in critically ill patients. This classification has not yet been validated. Sleep disturbance in the ICU is a multifactorial problem. The ICU environment, mechanical ventilation, medication, as well as the critical illness itself have been reported as important sleep disturbing factors. Secretion of sleep hormone, melatonin, expressing circadian rhythmicity was found abolished or phase delayed in critically ill patients. Various interventions have been tested in several studies aiming to improve sleep quality and circadian rhythm in the ICU. The results of these studies were inconclusive due to using the sleep assessment methods other than PSG or the absence of a reliable sleep scoring tool for the analysis of the PSG findings in this patient population. Development of a valid sleep scoring classification is essential for further sleep research in critically ill patients.

Melatonin Supplementation May Improve the Outcome of Patients with Hemorrhagic Stroke in the Intensive Care Unit

Objective:

Although mechanical ventilation is frequently a life-saving therapy, its use can result in unwanted side effects. It has been well documented that the choice of sedating agent may influence the duration of mechanical ventilation. Melatonin is a sedative and analgesic agent without any respiratory depressant effect which makes it an attractive adjuvant for sedation in the intubated patients. The aim of this study is to evaluate the effect of melatonin on the duration of mechanical ventilation in patients with hemorrhagic stroke.

Methods:

Forty adult intubated patients with hemorrhagic stroke, who were admitted to the Intensive Care Unit (ICU) within 24 h of onset, were enrolled in this randomized double-blind study. Subjects in the melatonin group received 30 mg of melatonin every night throughout the nasogastric tube. Length of ICU stay, mortality, and duration of mechanical ventilation were recorded for all patients.

Findings:

The duration of mechanical ventilation and length of ICU stay were shorter in patients who received melatonin in comparison with the control group, and this difference was statistically significant for the length of ICU stay and marginally significant for the duration of mechanical ventilation. Although not statistically significant, the mortality rate of the control group was 30%, almost double that of the study group (15%).

Conclusion:

Melatonin possesses hypnotic, analgesic, anti-inflammatory, and anti-oxidative properties that distinguish it as an attractive adjuvant in patients under mechanical ventilation. In conclusion, the administration of melatonin may facilitate the weaning process through decreasing the consumption of sedatives with respiratory depressant properties as well as preventing ventilator-associated lung injury.

Melatonin in Critically Ill Children

Melatonin, while best known for its chronobiologic functions, has multiple effects that may be relevant in critical illness. It has been used for circadian rhythm maintenance, analgesia, and sedation, and has antihypertensive, anti-inflammatory, antioxidant, antiapoptotic, and antiexcitatory effects. This review examines melatonin physiology in health, the current state of knowledge regarding endogenous melatonin production in pediatric critical illness, and the potential uses of exogenous melatonin in this population, including relevant information from basic sciences and other fields of medicine. Pineal melatonin production and secretion appears to be altered in critical illness, though understanding in pediatric critical illness is in early stages, with only 102 children reported in the current literature. Exogenous melatonin may be used for circadian rhythm disturbances and, within the critically ill population, holds promise for diseases involving oxidant stress. There are no studies of exogenous melatonin administration to critically ill children beyond the neonatal period.

Melatonin and melatonin agonists to prevent and treat delirium in critical illness: a systematic review protocol

BACKGROUND

Delirium is a syndrome characterized by acute fluctuations and alterations in attention and arousal. Critically ill patients are at particularly high risk, and those that develop delirium are more likely to experience poor clinical outcomes such as prolonged duration of ICU and hospital length of stay, and increased mortality. Melatonin and melatonin agonists (MMA) have the potential to decrease the incidence and severity of delirium through their hypnotic and sedative-sparing effects, thus improving health-related outcomes. The objective of this review is to synthesize the available evidence pertaining to the efficacy and safety of MMA for the prevention and treatment of ICU delirium.

METHODS

We will search Ovid MEDLINE, Web of Science, EMBASE, PsycINFO, the Cochrane Central Register of Controlled Trials (CENTRAL), and CINAHL to identify studies evaluating MMA in critically ill populations. We will also search http://apps.who.int/trialsearch for ongoing and unpublished studies and PROSPERO for registered reviews. We will not impose restrictions on language, date, or journal of publication. Authors will independently screen for eligible studies using pre-defined criteria; data extraction from eligible studies will be performed in duplicate. The Cochrane Risk of Bias Scale and the Newcastle-Ottawa Scale will be used to assess the risk of bias and quality of randomized and non-randomized studies, respectively. Our primary outcome of interest is delirium incidence, and secondary outcomes include duration of delirium, number of delirium- and coma-free days, use of physical and chemical (e.g., antipsychotics or benzodiazepines) restraints, duration of mechanical ventilation, ICU and hospital length of stay, mortality, long-term neurocognitive outcomes, hospital discharge disposition, and adverse events. We will use Review Manager (RevMan) to pool effect estimates from included studies. We will present results as relative risks with 95% confidence intervals for dichotomous outcomes and as mean differences, or standardized mean differences, for continuous outcomes.

DISCUSSION

Current guidelines make no pharmacological recommendations for either the prevention or treatment of ICU delirium. This systematic review will synthesize the available evidence on the efficacy and safety of MMA for this purpose, thus potentially informing clinical decision-making and improving patient outcomes.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42015024713.

Sleep Neurobiology and Critical Care Illness

The intensive care unit (ICU) environment is not propitious for restoring sleep and many studies have reported that critically ill patients have severe sleep disruptions. However, sleep alterations in critically ill patients are specific and differ significantly from those in ambulatory patients. Polysomnographic patterns of normal sleep are frequently lacking in critically ill patients and the neurobiology of sleep is important to consider regarding alternative methods to quantify sleep in the ICU. This article discusses elements of sleep neurobiology affecting the specificity of sleep patterns and sleep alterations in patients admitted to the ICU.

Circadian Rhythm Disruption in the Critically Ill: An Opportunity for Improving Outcomes

OBJECTIVES

Circadian rhythms are severely disrupted among the critically ill. These circadian arrhythmias impair mentation, immunity, autonomic function, endocrine activity, hormonal signaling, and ultimately healing. In this review, we present a modern model of circadian disruption among the critically ill, discuss causes of these circadian arrhythmias, review observational and intervention studies of the effects of circadian-rhythm-restoring factors on medical outcomes, and identify needed key trials of circadian interventions in the critically ill.

DATA SOURCES

MEDLINE, EMBASE, PsychINFO, Google Scholar through December 2014.

STUDY SELECTION

Articles relevant to circadian rhythms, melatonin, and light in the critically ill were selected.

DATA EXTRACTION AND DATA SYNTHESIS

Articles were synthesized for this review of circadian arrhythmia and the use of circadian-rhythm-restoring interventions among the critically ill.

CONCLUSIONS

Circadian disruption often demonstrates serial degradation: initially, the amplitude attenuates along with delayed circadian phase. With increasing acuity of illness, circadian rhythmicity may be lost entirely. Causes of chronodisruption may be environmental or internal to the patient. In particular, inadequate daytime illumination and nocturnal light pollution disrupt healthy circadian periodicity. Internal causes of circadian arrhythmia include critical illness itself and subjective experience of distress and pain. Observational studies of windowed rooms and real-time ambient lighting have found that physiologic light-dark patterns may support recovery from critical illness. Studies of early morning bright light or evening melatonin agonists have found improved rates of delirium, enhanced sleep, and lower arrhythmia prevalence. The current evidence base emphasizes that lighting and melatoninergic interventions deserve to be tested in full-scale trials.

Dynamic light application therapy to reduce the incidence and duration of delirium in intensive-care patients: a randomised controlled trial

BACKGROUND

Disturbed circadian rhythm is a potentially modifiable cause of delirium among patients in intensive-care units (ICUs). Bright-light therapy in the daytime can realign circadian rhythm and reduce the incidence of delirium. We investigated whether a high-intensity dynamic light application (DLA) would reduce ICU-acquired delirium.

METHODS

This was a randomised, controlled, single-centre trial of medical and surgical patients admitted to the ICU of a teaching hospital in the Netherlands. Patients older than 18 years, expected to stay in the ICU longer than 24 h and who could be assessed for delirium were randomised to DLA or normal lighting (control), according to a computer-generated schedule. The DLA was administered through ceiling-mounted fluorescent tubes that delivered bluish-white light up to 1700 lux between 0900 h and 1600 h, except for 1130-1330 h, when the light was dimmed to 300 lux. The light could only be turned off centrally by investigators. Control light levels were 300 lux and lights could be turned on and off from inside the room. The primary endpoint was the cumulative incidence of ICU-acquired delirium. Analyses were by intention to treat and per protocol. The study was terminated prematurely after an interim analysis for futility. This study is registered with Clinicaltrials.gov, number NCT01274819.

FINDINGS

Between July 1, 2011, and Sept 9, 2013, 734 patients were enrolled, 361 in the DLA group and 373 in the control group. Delirium occurred in 137 (38%) of 361 DLA patients and 123 (33%) of 373 control patients (odds ratio 1·24, 95% CI 0·92-1·68, p=0·16). No adverse events were noted in patients or staff.

INTERPRETATION

DLA as a single intervention does not reduce the cumulative incidence of delirium. Bright-light therapy should be assessed as part of a multicomponent strategy.

FUNDING

None.

Sleep neurobiology and critical care illness

The intensive care unit (ICU) environment is not propitious for restoring sleep and many studies have reported that critically ill patients have severe sleep disruptions. However, sleep alterations in critically ill patients are specific and differ significantly from those in ambulatory patients. Polysomnographic patterns of normal sleep are frequently lacking in critically ill patients and the neurobiology of sleep is important to consider regarding alternative methods to quantify sleep in the ICU. This article discusses elements of sleep neurobiology affecting the specificity of sleep patterns and sleep alterations in patients admitted to the ICU.

Circadian dysrhythmias in the intensive care unit

Circadian rhythms underlie nearly all physiologic functions and organ systems. Circadian abnormalities have attendant implications for critical illness survival. The intensive care unit (ICU) environment, with its lack of diurnal variation in sound, light, and social cues, may precipitate circadian dysrhythmias. Additional features of critical care, including mechanical ventilation and sedation, likely perpetuate circadian misalignment. Critical illness itself, from sepsis to severe brain injury, can compromise circadian health. Use of daylight, time-restricted feedings, and administration of melatonin can possibly restore circadian rhythm. However, further study is necessary to assess the effectiveness of these interventions and their impact on ICU outcomes.

Positive and negative effects of mechanical ventilation on sleep in the ICU: a review with clinical recommendations

PURPOSE

Sleep is an essential physiologic process that helps to restore normal body homeostasis. Sleep disturbances have been shown to be associated with poor clinical outcomes, such as a greater risk of cardiovascular disease and increasing mortality. Critically ill patients, particularly those receiving mechanical ventilation, may be more susceptible to sleep disruption.

METHODS AND RESULTS

Mechanical ventilation is an important factor influencing sleep in critically ill patients as it may have positive or negative effects, depending on patient population, mode, and specific settings. Other causes of sleep disruption include the acute illness itself, the daily routine care, and the effects of medications. Improving sleep in patients admitted to an intensive care unit has the potential to improve both short- and long-term clinical outcomes. In this article we review the specific aspects of sleep in critically ill mechanically ventilated patients, including abnormal sleep patterns and loss of circadian rhythm, as well as the effects of mechanical ventilation and intravenous sedatives on sleep quality and quantity.

CONCLUSIONS

We provide recommendations for clinicians regarding optimal ventilatory settings and discuss fields for future research.

Let there be light and darkness: findings from a prestudy concerning cycled light in the intensive care unit environment

The present study reports findings concerning light in an intensive care unit setting presented from 3 aspects, giving a wide view. The first part is a systematic review of intervention studies concerning cycled light compared with dim light/noncycled light. The findings showed that cycled light may be beneficial to preterm infant health. Second, a lighting intervention in the intensive care unit is presented, comparing and assessing experience of this lighting environment with that of an ordinary room. Significant differences were shown in hedonic tone, favoring the intervention environment. In the third part, measured illuminance, luminance, and irradiance values achieved in the lighting intervention room and ordinary room lighting are reported.

Lighting, sleep and circadian rhythm: An intervention study in the intensive care unit

Patients in an intensive care unit (ICU) may risk disruption of their circadian rhythm. In an intervention research project a cycled lighting system was set up in an ICU room to support patients' circadian rhythm. Part I aimed to compare experiences of the lighting environment in two rooms with different lighting environments by lighting experiences questionnaire. The results indicated differences in advantage for the patients in the intervention room (n=48), in perception of daytime brightness (p=0.004). In nighttime, greater lighting variation (p=0.005) was found in the ordinary room (n=52). Part II aimed to describe experiences of lighting in the room equipped with the cycled lighting environment. Patients (n=19) were interviewed and the results were presented in categories: "A dynamic lighting environment", "Impact of lighting on patients' sleep", "The impact of lighting/lights on circadian rhythm" and "The lighting calms". Most had experiences from sleep disorders and half had nightmares/sights and circadian rhythm disruption. Nearly all were pleased with the cycled lighting environment, which together with daylight supported their circadian rhythm. In night's actual lighting levels helped patients and staff to connect which engendered feelings of calm.

A preliminary study on the relationships between diurnal melatonin secretion profile and sleep variables in patients emergently admitted to the coronary care unit

To clarify the significance of melatonin secretion under intensive care conditions, we investigated melatonin secretion profiles and sleep parameters of 23 patients just after admission to the coronary care unit (CCU) and 19 age-matched controls. Sleep parameters were evaluated by actigraphy, and melatonin secretion was assessed by measuring the urinary 6-sulphatoxy melatonin (6-SMT). 6-SMT secretion was lower and nocturnal sleep parameters were less satisfactory in the subjects than those in the controls, and there were positive correlations between these variables, particularly in the subject patients. The lowered melatonin secretion might be involved in the mechanism of insomnia in CCU patients.

Emerging Role of Melatonin and Melatonin Receptor Agonists in Sleep and Delirium in Intensive Care Unit Patients

Delirium, an acute state of mental confusion, can lead to many adverse sequelae in intensive care unit (ICU) patients. Although the etiology of ICU delirium is often multifactorial, and at times not fully understood, sleep deprivation is considered to be a major contributing factor to its development. It has been postulated that administration of exogenous melatonin and melatonin receptor agonists such as ramelteon may prevent delirium by promoting nocturnal sleep in ICU patients. The purpose of this review is to summarize the pharmacology of melatonin and melatonin receptor agonists and investigate their potential roles in sleep promotion and delirium prevention in ICU patients. Although few studies evaluating the impact of melatonergic agents on sleep and delirium in the ICU have been completed, some data suggest their potential positive effects on sleep and delirium. However, large-scale randomized controlled trials are warranted to determine the optimal role of melatonergic agents in the prevention of ICU delirium.

Sleep disturbance in older ICU patients

Maintaining a stable and adequate sleeping pattern is associated with good health and disease prevention. As a restorative process, sleep is important for supporting immune function and aiding the body in healing and recovery. Aging is associated with characteristic changes to sleep quantity and quality, which make it more difficult to adjust sleep–wake rhythms to changing environmental conditions. Sleep disturbance and abnormal sleep–wake cycles are commonly reported in seriously ill older patients in the intensive care unit (ICU). A combination of intrinsic and extrinsic factors appears to contribute to these disruptions. Little is known regarding the effect that sleep disturbance has on health status in the oldest of old (80+), a group, who with diminishing physiological reserve and increasing prevalence of frailty, is at a greater risk of adverse health outcomes, such as cognitive decline and mortality. Here we review how sleep is altered in the ICU, with particular attention to older patients, especially those aged ≥80 years. Further work is required to understand what impact sleep disturbance has on frailty levels and poor outcomes in older critically ill patients.

'Chronomics' in ICU: circadian aspects of immune response and therapeutic perspectives in the critically ill

Complex interrelations exist between the master central clock, located in the suprachiasmatic nuclei of the hypothalamus, and several peripheral clocks, such as those found in different immune cells of the body. Moreover, external factors that are called ‘timekeepers’, such as light/dark and sleep/wake cycles, interact with internal clocks by synchronizing their different oscillation phases. Chronobiology is the science that studies biologic rhythms exhibiting recurrent cyclic behavior. Circadian rhythms have a duration of approximately 24 h and can be assessed through chronobiologic analysis of time series of melatonin, cortisol, and temperature. Critically ill patients experience severe circadian deregulation due to not only the lack of effective timekeepers in the intensive care unit (ICU) environment but also systemic inflammation. The latter has been found in both animal and human studies to disrupt circadian rhythmicity of all measured biomarkers. The aims of this article are to describe circadian physiology during acute stress and to discuss the effects of ICU milieu upon circadian rhythms, in order to emphasize the value of considering circadian-immune disturbance as a potential tool for personalized treatment. Thus, besides neoplastic processes, critical illness could be linked to what has been referred as ‘chronomics’: timing and rhythm. In addition, different therapeutic perspectives will be presented in association with environmental approaches that could restore circadian connection and hasten physical recovery.

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.

Patterns of opiate, benzodiazepine, and antipsychotic drug dosing in older patients in a medical intensive care unit

BACKGROUND

Anecdotal observation suggests that older patients in medical intensive care units receive higher doses of psychoactive medications during evening shifts than day and night shifts.

OBJECTIVES

To determine the dosing patterns and total doses of fentanyl, lorazepam, and haloperidol according to nursing shift in a cohort of older patients in a medical intensive care unit.

METHODS

The sample consisted of 309 patients 60 years and older admitted to the medical intensive care unit at Yale-New Haven Hospital, New Haven, Connecticut. Data on time, dosage, and route of administration of the drugs were collected. Data were analyzed by using a Bayesian random effects Poisson model adjusted for individual heterogeneity, excess zero doses, and important clinical covariates.

RESULTS

Mean age of the patients was 75 years; 58% received fentanyl, 55% received lorazepam, and 32% received haloperidol. Although dosing with fentanyl did not differ according to shift, doses of both lorazepam and haloperidol were higher during the evening shifts (4 pm to midnight) than during the day or night shifts. Compared with women, men received higher doses of both haloperidol and lorazepam and variability between shifts was greater.

CONCLUSIONS

In this longitudinal, observational sample of older patients, data indicated a positive association between dose levels of lorazepam and haloperidol during the evening nursing shifts relative to other shifts. Further investigation is needed to determine potential causes and to evaluate the impact on outcomes of sleep deprivation and delirium.

High endogenous melatonin levels in critically ill children: a pilot study

OBJECTIVE

To evaluate the serum melatonin levels in critically ill pediatric patients and to test the effect of light on the melatonin's circadian rhythm. Data on melatonin secretion in critically ill pediatric subjects are lacking.

STUDY DESIGN

We investigated the serum melatonin levels of 16 sedated and mechanically ventilated patients in a pediatric intensive care unit. Children (mean age, 5.1 ± 3.1 years) were randomly assigned to a dark-exposed or to a light-exposed group to evaluate the effects of light on serum melatonin concentrations. Blood samples for serum melatonin analysis were collected at 10 p.m., 1 a.m., 3 a.m., 5 a.m., 8 a.m., and 12 p.m.

RESULTS

The melatonin circadian rhythm was severely disrupted in critically ill children; light exposure lowered serum melatonin even in a context of highly altered circadian cycle; melatonin peaks were greater for healthy age-matched children.

CONCLUSION

The high melatonin levels in the critically ill children may be a response to counteract the elevated oxidative stress associated with serious diseases. Whether these elevated melatonin levels confer any beneficial effects in pediatric critically ill patients remains unknown.