Effect of daily sedative interruption on sleep stages of mechanically ventilated patients receiving midazolam by infusion

Effect of prolonged sedation with dexmedetomidine, midazolam, propofol, and sevoflurane on sleep homeostasis in rats

BACKGROUND

Sleep disruption is a common occurrence during medical care and is detrimental to patient recovery. Long-term sedation in the critical care setting is a modifiable factor that affects sleep, but the impact of different sedative-hypnotics on sleep homeostasis is not clear.

METHODS

We conducted a systematic comparison of the effects of prolonged sedation (8 h) with i.v. and inhalational agents on sleep homeostasis. Adult Sprague-Dawley rats (n=10) received dexmedetomidine or midazolam on separate days. Another group (n=9) received propofol or sevoflurane on separate days. A third group (n=12) received coadministration of dexmedetomidine and sevoflurane. Wakefulness (wake), slow-wave sleep (SWS), and rapid eye movement (REM) sleep were quantified during the 48-h post-sedation period, during which we also assessed wake-associated neural dynamics using two electroencephalographic measures: theta-high gamma phase-amplitude coupling and high gamma weighted phase-lag index.

RESULTS

Dexmedetomidine-, midazolam-, or propofol-induced sedation increased wake and decreased SWS and REM sleep (P<0.0001) during the 48-h post-sedation period. Sevoflurane produced no change in SWS, decreased wake for 3 h, and increased REM sleep for 6 h (P<0.02) post-sedation. Coadministration of dexmedetomidine and sevoflurane induced no change in wake (P>0.05), increased SWS for 3 h, and decreased REM sleep for 9 h (P<0.02) post-sedation. Dexmedetomidine, midazolam, and coadministration of dexmedetomidine with sevoflurane reduced wake-associated phase-amplitude coupling (P≤0.01). All sedatives except sevoflurane decreased wake-associated high gamma weighted phase-lag index (P<0.01).

CONCLUSIONS

In contrast to i.v. drugs, prolonged sevoflurane sedation produced minimal changes in sleep homeostasis and neural dynamics. Further studies are warranted to assess inhalational agents for long-term sedation and sleep homeostasis.

Sleep assessment in critically ill adults: A systematic review and meta-analysis

PURPOSE

To systematically review sleep evaluation, characterize sleep disruption, and explore effects of sleepdisruption on outcomes in adult ICU patients.

MATERIALS AND METHODS

We systematically searched databases from May 1969 to June 2021 (PROSPERO protocol number: CRD42020175581). Prospective and retrospective studies were included studying sleep in critically ill adults, excluding patients with sleep or psychiatric disorders. Meta-regression methods were applied when feasible.

RESULTS

132 studies (8797 patients) were included. Fifteen sleep assessment methods were identified, with only two validated. Patients had significant sleep disruption, with low sleep time, and low proportion of restorative rapid eye movement (REM). Sedation was associated with higher sleep efficiency and sleep time. Surgical versus medical patients had lower sleep quality. Patients on ventilation had a higher amount of light sleep. Meta-regression only suggested an association between total sleep time and occurrence of delirium (p < 0.001, 15 studies, 519 patients). Scarce data precluded further analyses. Sleep characterized with polysomnography (PSG) correlated well with actigraphy and Richards Campbell Sleep Questionnaire (RCSQ).

CONCLUSIONS

Sleep in critically ill patients is severely disturbed, and actigraphy and RCSQ seem reliable alternatives to PSG. Future studies should evaluate impact of sleep disruption on outcomes.

Cognitive Dysfunction After Analgesia and Sedation: Out of the Operating Room and Into the Pediatric Intensive Care Unit

In the midst of concerns for potential neurodevelopmental effects after surgical anesthesia, there is a growing awareness that children who require sedation during critical illness are susceptible to neurologic dysfunctions collectively termed pediatric post-intensive care syndrome, or PICS-p. In contrast to healthy children undergoing elective surgery, critically ill children are subject to inordinate neurologic stress or injury and need to be considered separately. Despite recognition of PICS-p, inconsistency in techniques and timing of post-discharge assessments continues to be a significant barrier to understanding the specific role of sedation in later cognitive dysfunction. Nonetheless, available pediatric studies that account for analgesia and sedation consistently identify sedative and opioid analgesic exposures as risk factors for both in-hospital delirium and post-discharge neurologic sequelae. Clinical observations are supported by animal models showing neuroinflammation, increased neuronal death, dysmyelination, and altered synaptic plasticity and neurotransmission. Additionally, intensive care sedation also contributes to sleep disruption, an important and overlooked variable during acute illness and post-discharge recovery. Because analgesia and sedation are potentially modifiable, understanding the underlying mechanisms could transform sedation strategies to improve outcomes. To move the needle on this, prospective clinical studies would benefit from cohesion with regard to datasets and core outcome assessments, including sleep quality. Analyses should also account for the wide range of diagnoses, heterogeneity of this population, and the dynamic nature of neurodevelopment in age cohorts. Much of the related preclinical evidence has been studied in comparatively brief anesthetic exposures in healthy animals during infancy and is not generalizable to critically ill children. Thus, complementary animal models that more accurately "reverse translate" critical illness paradigms and the effect of analgesia and sedation on neuropathology and functional outcomes are needed. This review explores the interactive role of sedatives and the neurologic vulnerability of critically ill children as it pertains to survivorship and functional outcomes, which is the next frontier in pediatric intensive care.

Clinical Practice Guidelines for the Prevention and Management of Pain, Agitation/Sedation, Delirium, Immobility, and Sleep Disruption in Adult Patients in the ICU

OBJECTIVE

To update and expand the 2013 Clinical Practice Guidelines for the Management of Pain, Agitation, and Delirium in Adult Patients in the ICU.

DESIGN

Thirty-two international experts, four methodologists, and four critical illness survivors met virtually at least monthly. All section groups gathered face-to-face at annual Society of Critical Care Medicine congresses; virtual connections included those unable to attend. A formal conflict of interest policy was developed a priori and enforced throughout the process. Teleconferences and electronic discussions among subgroups and whole panel were part of the guidelines' development. A general content review was completed face-to-face by all panel members in January 2017.

METHODS

Content experts, methodologists, and ICU survivors were represented in each of the five sections of the guidelines: Pain, Agitation/sedation, Delirium, Immobility (mobilization/rehabilitation), and Sleep (disruption). Each section created Population, Intervention, Comparison, and Outcome, and nonactionable, descriptive questions based on perceived clinical relevance. The guideline group then voted their ranking, and patients prioritized their importance. For each Population, Intervention, Comparison, and Outcome question, sections searched the best available evidence, determined its quality, and formulated recommendations as "strong," "conditional," or "good" practice statements based on Grading of Recommendations Assessment, Development and Evaluation principles. In addition, evidence gaps and clinical caveats were explicitly identified.

RESULTS

The Pain, Agitation/Sedation, Delirium, Immobility (mobilization/rehabilitation), and Sleep (disruption) panel issued 37 recommendations (three strong and 34 conditional), two good practice statements, and 32 ungraded, nonactionable statements. Three questions from the patient-centered prioritized question list remained without recommendation.

CONCLUSIONS

We found substantial agreement among a large, interdisciplinary cohort of international experts regarding evidence supporting recommendations, and the remaining literature gaps in the assessment, prevention, and treatment of Pain, Agitation/sedation, Delirium, Immobility (mobilization/rehabilitation), and Sleep (disruption) in critically ill adults. Highlighting this evidence and the research needs will improve Pain, Agitation/sedation, Delirium, Immobility (mobilization/rehabilitation), and Sleep (disruption) management and provide the foundation for improved outcomes and science in this vulnerable population.

Incidence of tolerance in children undergoing repeated administration of propofol for proton radiation therapy: a retrospective study

Background

Propofol is an excellent hypnotic drug for use in repeated radiation procedures in young children. To date, tolerance to propofol generally does not develop in pediatric patients undergoing radiation therapy. However, several studies have suggested that there may be potential for development of tolerance to propofol. The aim of this study was to evaluate the development of a tolerance to propofol used for repeated deep sedation in children undergoing proton radiation therapy (PRT).

Methods

All children undergoing PRT at our institution between December 2015 and January 2018 were eligible for inclusion in this study. Sedation was induced by a bolus dose of propofol (2.0 mg.kg^− 1) followed by a continuous infusion of 250 μg.kg^− 1.min^− 1 via an infusion pump to achieve deep sedation. Sedation was maintained with the propofol infusion of 200 μg.kg^− 1.min^− 1, which was adjusted in 25 μg.kg^− 1.min^− 1 increments up or down as necessary to ensure deep sedation. The primary outcome was mean doses of propofol over time.

Results

Fifty-eight children were analyzed. The mean (SD) age was 4.5 (2.1) years. The mean (SD) number of treatment sessions was 19 (7). Fifteen patients (26%) developed tolerance to propofol. However, there were no significant differences between the children who developed tolerance and the children who did not develop tolerance in mean propofol dose and awakening time over time (p = 0.887 and P = 0.652, respectively). Age, the number of PRT, and attending anesthesiologists was not significantly associated with the incidence of tolerance to propofol.

Conclusion

Repeated prolonged deep sedation for PRT elicited multiple times over several weeks in young children using propofol did not develop tolerance in 74% of patients. Although the incidence of 26% tolerance to propofol may still be present, the increase in propofol dose was minimal. Therefore, the use of repeated propofol for children was safe.

The effects of mechanical ventilation on the quality of sleep of hospitalised patients in the Intensive Care Unit

Aim

To examine the effects of mechanical ventilation on the quality of sleep in patients in the intensive care unit (ICU) using recent and relevant literature.

Methods

To verify the examined objective, the results of the analysis of available original scientific works have been used including defined inclusion/exclusion criteria and search strategy. Appropriate works found were analysed further. The applied methodology was in line with the general principles of Evidence-Based Medicine. The following literary databases were used: CINAHL, Medline and gray literature: Google Scholar.

Results

A total of 91 trials were found. Eleven of these relevant to the follow-up analysis were selected: all trials were carried out under real ICU conditions and the total of 192 patients were included in the review. There is an agreement within all trials that sleep in patients requiring mechanical ventilation is disturbed. Most reviewed trials have shown that mechanical ventilation is probably not the main factor causing sleep disturbances, but an appropriate ventilation strategy can significantly help to improve its quality by reducing the frequency of the patient-ventilator asynchrony.

Conclusion

Based on the analysis, it appears that an appropriate ventilation mode setting can have a beneficial effect on the quality of sleep in ICU patients.

Perceptions and Practices Regarding Sleep in the Intensive Care Unit. A Survey of 1,223 Critical Care Providers

RATIONALE

Poor sleep affects a majority of critically ill patients and is believed to be associated with adverse intensive care unit (ICU) outcomes such as delirium. While recent guidelines recommend sleep promotion efforts to improve delirium and other ICU outcomes, little is known about critical care providers' beliefs regarding sleep in the ICU.

OBJECTIVES

To evaluate providers' perceptions and practices regarding sleep in the ICU.

METHODS

From April to July 2014, the Sleep in the ICU Survey was disseminated to ICU providers via institutional e-mail lists and four international critical care society distribution lists.

MEASUREMENTS AND MAIN RESULTS

A total of 1,223 surveys were completed by providers from 24 countries. Respondents were primarily nurses (59%) or physicians (39%). Most respondents indicated that ICU patients experienced "poor" or "very poor" sleep (75%) and that poor sleep could affect the ICU recovery process (88%). Respondents also felt that poor sleep was associated with negative ICU outcomes such as the development of delirium (97%), longer length of stay (88%), poor participation in physical therapy (87%), and delayed liberation from mechanical ventilation (83%). The minority (32%) of providers had sleep-promoting protocols; these providers tended to believe their patients slept longer and experienced better sleep quality.

CONCLUSIONS

Though most clinicians believe that sleep in the ICU is poor and adversely affects patient outcomes, a minority of the ICUs represented by our respondents have sleep promotion protocols. These findings highlight discordant provider perceptions and practices surrounding sleep in the ICU, as well as a possible lack of available evidence-based guidelines for promoting sleep in the ICU.

Polypharmacy and Delirium in Critically Ill Older Adults: Recognition and Prevention

Among older adults, polypharmacy is a sequelae of admission to the intensive care unit and is associated with increased medication-associated adverse events, drug interactions, and health care costs. Delirium is prevalent in critically ill geriatric patients and medications remain an underappreciated modifiable risk for delirium in this setting. This article reviews the literature on polypharmacy and delirium, with a focus on highlighting the relationships between polypharmacy and delirium in critically ill, older adults. Discussed are clinician strategies on how to recognize and reduce medication-associated delirium and recommendations that help prevent polypharmacy when interventions to reduce the burden of delirium in this vulnerable population are being formulated.

Pharmacological interventions to improve sleep in hospitalised adults: a systematic review

OBJECTIVES

Patients often suffer from disturbed sleep in hospital. Poor-quality sleep in hospitalised patients has been associated with significant morbidity and pharmacological sleep aids are often prescribed. The objective of this systematic review is to evaluate the comparative efficacy and safety of pharmacological interventions used for sleep in hospitalised patients.

SETTING/PARTICIPANTS

We searched MEDLINE, Embase, the Cochrane database and grey literature for prospective studies that evaluated sleep in hospitalised adults after a pharmacological intervention.

PRIMARY AND SECONDARY OUTCOME MEASURES

Two reviewers assessed studies for inclusion and extracted data for efficacy outcomes, including sleep efficiency, sleep latency, sleep fragmentation and objectively measured sleep stage distribution. Risk of bias was assessed and meta-analyses were planned contingent upon homogeneity of the included studies.

RESULTS

After screening 1920 citations, 15 studies involving 861 patients were included. Medications studied included benzodiazepines, nonbenzodiazepine sedatives, melatonin, propofol and dexmedetomidine. Five studies were deemed to be of high quality. Heterogeneity and variable outcome reporting precluded meta-analysis in most cases. No consistent trends with respect to sleep efficiency, quality or interruptions were observed identifying a drug or drug class as superior to another or no treatment. Benzodiazepines appeared to be better than no treatment with respect to sleep latency, but this was not consistently demonstrated across all studies. Sleep stage distribution shows that sleep in hospital is dominated by stages N1 and N2.

CONCLUSIONS

There is insufficient evidence to suggest that pharmacotherapy improves the quality or quantity of sleep in hospitalised patients suffering from poor sleep. No drug class or specific drug was identified as superior even when compared to placebo or no treatment. Although 15 studies were included, the quality of evidence was limited by their quality and size. Larger, better-designed trials in hospitalised adults are needed.

The Optimum Level of Sevoflurane in Pediatric Echocardiography

Sevoflurane is shown to be safe and effective in pediatric echocardiography. This study explores the optimum level in pediatric echocardiography. One hundred and twenty children, with an age range of 35 days-3 years, were included in this study. The children with severe cyanotic congenital heart disease or severe pneumonia, which was Grade I or II according to the American College of Physicians Guideline Grading, were excluded. All children received the anesthesia with sevoflurane. The inhalation anesthesia level decreased from 2.5 to 1.0 %, with a decrement of 0.5 %. The induction time (T0), echocardiography time (T1), and time to awakening (T2) in each child were recorded, and the changes in the blood pressure, heart rate, breath, and oxygen saturation in each child were also monitored. The Ramsay scale scoring during anesthesia and the case number of failure in echocardiography in each group were also recorded. When the level of sevoflurane inhalation was maintained at 1.0 %, the childrens' scores were low, including 8 incompliant children, and p < 0.05 in comparison with other groups. The scores increased as the sevoflurane inhalation level increased. When the sevoflurane inhalation increased to 1.5 %, the children could sleep with stable blood pressure, and no dysphoria occurred during the echocardiography. When the sevoflurane inhalation level increased to 2.5 %, the Ramsay scores did not increase. However, the T2 significantly increased (p < 0.05). The blood pressure and heart rate in each group did not change significantly. With the premise of safety and efficacy in children, the optimum level of sevoflurane in pediatric echocardiography was 1.5-2.0 %.

Sleep and Mechanical Ventilation in Critical Care

Sleep disturbances in critically ill mechanically ventilated patients are common. Although many factors may potentially contribute to sleep loss in critical care, issues around mechanical ventilation are among the more complex. Sleep deprivation has systemic effects that may prolong the need for mechanical ventilation and length of stay in critical care and result in worse outcomes. This article provides a brief review of the physiology of sleep, physiologic changes in breathing associated with sleep, and the impact of mechanical ventilation on sleep. A summary of the issues regarding research studies to date is also included. Recommendations for the critical care nurse are provided.

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.

A meta-analysis of sleep-promoting interventions during critical illness

BACKGROUND

Sleep quality and quantity are severely reduced in critically ill patients receiving mechanical ventilation with a potential for adverse consequences. Our objective was to synthesize the randomized controlled trials (RCTs) that measured the efficacy of sleep-promoting interventions on sleep quality and quantity in critically ill patients.

METHODS

We included RCTs that objectively measured sleep with electroencephalography or its derivatives and excluded observational studies and those that measured sleep by subjective reports. The research was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

Of 6022 studies identified, 13 met eligibility criteria involving 296 critically ill patients. Eight trials looked at different modes of mechanical ventilation as sleep interventions, and the remaining 5 involved pharmacologic, nonpharmacologic, or environmental interventions. Meta-analysis of the studies revealed that sleep-promoting interventions improved sleep quantity (pooled standardized mean difference [SMD], 0.37; 95% confidence interval [CI], 0.05-0.69; P = .02) and sleep quality through reduction in sleep fragmentation (SMD, -0.31; 95% CI, -0.60 to -0.01; P = .04). Subgroup analysis revealed that timed modes of ventilation improved sleep quantity when compared with spontaneous modes of ventilation (SMD, 0.45; 95% CI, 0.10-0.81; P = .01). Nonmechanical ventilation interventions tended to improve sleep quantity (SMD, 0.65; 95% CI, -0.03 to 1.33; P = .06) and to reduce sleep fragmentation (SMD, -0.29; 95% CI, -0.61 to 0.03; P = .07).

CONCLUSIONS

The synthesized evidence suggests that both mechanical ventilation- and nonmechanical ventilation-based therapies improve sleep quantity and quality in critically ill patients, but the clinical significance is unclear. In the future, adequately powered multicenter RCTs involving pharmacologic interventions to promote sleep in critically ill patients are warranted.

Effect of sedative-hypnotics, anesthetics and analgesics on sleep architecture in obstructive sleep apnea

The perioperative care of obstructive sleep apnea (OSA) patients is currently receiving much attention due to an increased risk for complications. It is established that postoperative changes in sleep architecture occur and this may have pathophysiological implications for OSA patients. Upper airway muscle activity decreases during rapid eye movement sleep (REMS). Severe OSA patients exhibit exaggerated chemoreceptor-driven ventilation during non-rapid eye movement sleep (NREMS), which leads to central and obstructive apnea. This article critically reviewed the literature relevant to preoperative screening for OSA, prevalence of OSA in surgical populations and changes in postoperative sleep architecture relevant to OSA patients. In particular, we addressed three questions in regard to the effects of sedative-hypnotics, anesthetics and analgesics on sleep architecture, the underlying mechanisms and the relevance to OSA. Indeed, these classes of drugs alter sleep architecture, which likely significantly contributes to abnormal postoperative sleep architecture, exacerbation of OSA and postoperative complications.

Feasibility study of unattended polysomnography in medical intensive care unit patients

OBJECTIVES

To evaluate the feasibility of using unattended, portable polysomnography (PSG) to measure sleep among patients in the medical intensive care unit (MICU).

BACKGROUND

Accurate measurement of sleep is critical to studies of MICU sleep deprivation. Although PSG is the gold standard, there is limited data regarding the feasibility of utilizing unattended, portable PSG modalities in the MICU.

METHODS

MICU based observational pilot study. We conducted unattended, 24-h PSG studies in 29 patients. Indicators of feasibility included attainment of electroencephalography data sufficient to determine sleep stage, sleep efficiency, and arousal indices.

RESULTS

Electroencephalography data were not affected by electrical interference and were of interpretable quality in 27/29 (93%) of patients. Overnight sleep efficiency was 48% reflecting a mean overnight sleep duration of 3.7 h.

CONCLUSIONS

Unattended, portable PSG produces high quality sleep data in the MICU and can facilitate investigation of sleep deprivation among critically ill patients. Patient sleep was short and highly fragmented.

Daily sedation interruption versus no daily sedation interruption for critically ill adult patients requiring invasive mechanical ventilation

BACKGROUND

Daily sedation interruption (DSI) is thought to limit drug bioaccumulation, promote a more awake state, and thereby reduce the duration of mechanical ventilation. Available evidence has shown DSI to either reduce, not alter, or prolong the duration of mechanical ventilation.

OBJECTIVES

The primary objective of this review was to compare the total duration of invasive mechanical ventilation for critically ill adult patients requiring intravenous sedation who were managed with DSI versus those with no DSI. Our other objectives were to determine whether DSI influenced mortality, intensive care unit (ICU) and hospital lengths of stay, adverse events, the total doses of sedative drug administered, and quality of life.

SEARCH METHODS

We searched, from database inception to February 2014, the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2014, Issue 1); MEDLINE (OvidSP); EMBASE (OvidSP); CINAHL (EBSCOhost); Latin American and Caribbean Health Sciences Literature (LILACS); Web of Science Science Citation Index; Database of Abstracts of Reviews of Effects (DARE); the Health Technology Assessment Database (HTA Database); trial registration websites, and reference lists of relevant articles. We did not apply language restrictions. The reference lists of all retrieved articles were reviewed for additional, potentially relevant studies.

SELECTION CRITERIA

We included randomized controlled trials that compared DSI with sedation strategies that did not include DSI in mechanically ventilated, critically ill adults.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and three authors assessed risk of bias. We contacted study authors for additional information as required. We combined data in forest plots using random-effects modelling. A priori subgroups and sensitivity analyses were performed.

MAIN RESULTS

Nine trials were used in the analysis (n = 1282 patients). These trials were found to be predominantly at low risk of bias. We did not find strong evidence of an effect of DSI on the total duration of ventilation. Pooled data from nine trials demonstrated a 13% reduction in the geometric mean, with relatively wide confidence intervals (CI) indicating imprecision (95% CI 26% reduction to 2% increase, moderate quality evidence). Similarly, we did not find strong evidence of an effect on ICU length of stay (-10%, 95% CI -20% to 3%, n = 9 trials, moderate quality evidence) or hospital length of stay (-6%, 95% CI -18% to 8%, n = 8 trials, moderate quality evidence). Heterogeneity for these three outcomes was moderate and statistically significant. The risk ratio for ICU mortality was 0.96 (95% CI 0.77 to 1.21, n = 7 trials, moderate quality evidence), for rate of accidental endotracheal tube removal 1.07 (95% CI 0.55 to 2.12, n = 6 trials, moderate quality evidence), for catheter removal 1.48 (95% CI 0.76 to 2.90, n = 4 trials), and for incidence of new onset delirium 1.02 (95% CI 0.91 to 1.13, n = 3 trials, moderate quality evidence). Differences in the doses of any drug used or quality of life score (Short Form (SF)-36) did not reach statistical significance. Tracheostomy was performed less frequently in the DSI group (RR 0.73, 95% CI 0.57 to 0.92, n = 6 trials, moderate quality evidence). Sensitivity analysis of unlogged data resulted in similar findings. Post hoc analysis to further explain heterogeneity, based on study country of origin, showed that studies conducted in North America resulted in a reduction in the duration of mechanical ventilation (-21%, 95% CI -33% to -5%, n = 5 trials).

AUTHORS' CONCLUSIONS

We have not found strong evidence that DSI alters the duration of mechanical ventilation, mortality, length of ICU or hospital stay, adverse event rates, drug consumption, or quality of life for critically ill adults receiving mechanical ventilation compared to sedation strategies that do not include DSI. We advise that caution should be applied when interpreting and applying the findings as the overall effect of treatment is always < 1 and the upper limit of the CI is only marginally higher than the no-effect line. These results should be considered unstable rather than negative for DSI given the statistical and clinical heterogeneity identified in the included trials.

Critical closing pressure during midazolam-induced sleep

The critical closing pressure (Pcrit) is the airway pressure at which the airway collapses and reflects the anatomical contribution to the genesis of obstructive sleep apnea. Pcrit is usually determined during non-rapid eye movement sleep at night, but has been determined under midazolam sedation during the day in the absence of sleep stage monitoring. Indeed, little is known about the effects of midazolam on sleep architecture. Moreover, deeper sedation with midazolam can decrease upper airway muscle activity and increase collapsibility compared with natural sleep. Pcrit under sedation has not been systematically compared with the usual method performed during natural sleep. Therefore, this study aimed to test the hypothesis that Pcrit following low doses of midazolam during the day would be comparable to Pcrit measured during natural sleep in the same patient. Fifteen men (age 54 ± 10 yr, body mass index 30 ± 4 kg/m(2)) with obstructive sleep apnea underwent a baseline standard overnight polysomnogram (apnea-hypopnea index 38 ± 22 events/h, range: 8-66 events/h), and Pcrit was determined during natural sleep and following midazolam. Sleep induction was obtained with low doses of midazolam (2.4 mg, range 2.0-4.4 mg), and sleep architecture was comparable to natural sleep. Natural sleep and induced sleep Pcrit were similar (-0.82 ± -3.44 and -0.97 ± 3.21 cmH(2)O, P = 0.663) and closely associated (intraclass correlation coefficient = 0.92; 95% confidence interval, 0.78-0.97, P < 0.001). Natural and midazolam-induced Pcrit correlated with obstructive sleep apnea severity, indicating that both Pcrit measures provided meaningful physiological information. Pcrit determined during the day with sleep induction is similar to natural overnight sleep and is a valid alternative approach in which to determine Pcrit.

Daily sedation interruption; a glass half empty?

The last decade witnessed an exponential rise in the number of publications addressing management of sedation during critical illness. In 1998 Kollef and colleagues1 suggested that the use of continuous infusions of sedatives may be associated with prolonged duration of mechanical ventilation and intensive care unit (ICU) stay. This was followed by a landmark study by Kress and colleagues2 who demonstrated significant reduction in ventilation time and ICU stay with daily interruption of sedative infusions (DSI). Subsequent investigations have been consistent with the notion that strategies that reduce sedation depth such as algorithms and protocols for sedation management3-5 and the use of validated sedation scales6 can improve patient outcomes. This academic exuberance led to an endorsement of these strategies, and in particular DSI, by the UK Department of Health ( www.clean-safe-care.nhs.uk ), the Institute for Healthcare Improvement ( www.IHI.org ) and Safer Health Care Now! ( www.saferhealthcarenow.ca ).