Presence of electroencephalogram burst suppression in sedated, critically ill patients is associated with increased mortality

Post-discharge insomnia symptoms are associated with quality of life impairment among survivors of acute lung injury

INTRODUCTION

Sleep disturbance is common during critical illness, yet little is known about its prevalence or role in post-discharge quality of life among high-risk acute lung injury (ALI) patients.

METHODS

In a prospective cohort of 61 mechanically ventilated ALI patients, we examined the association between insomnia symptoms and quality of life six months after discharge. Subjects completed surveys rating quality of life (MOS SF-36), post-traumatic stress disorder (PCL), and depression (PHQ-9). Using an individual item from the PCL, we defined insomnia symptoms as moderate or greater trouble falling or staying asleep in the past month. We performed multivariable linear regression to examine the association between insomnia symptoms and SF-36 physical and mental component summary scores, adjusting for PTSD and depression.

RESULTS

Forty subjects (85% of eligible) completed six-month questionnaires; 20 (50%) met criteria for insomnia symptoms. After adjustment for PTSD and depression, insomnia symptoms remained significantly associated with worse physical component summary scores (adjusted mean difference=-8.8; 95% CI: -15.0, -2.5; P<0.01).

CONCLUSIONS

Post-discharge insomnia symptoms were common and significantly associated with physical quality of life impairment among six-month ALI survivors, even after adjustment for PTSD and depression symptoms. Further studies are needed to validate these results and to characterize sleep disturbance after ALI using sleep-specific metrics.

Review articles: the effects of perioperative and intensive care unit sedation on brain organ dysfunction

Analgesia and sedation are routinely administered to patients in procedural suites, operating rooms, and intensive care units to permit invasive procedures, prevent pain and anxiety, reduce stress and oxygen consumption, allow mechanical ventilation, and for numerous other patient comfort and safety reasons. Increasing research and evidence, however, has implicated commonly prescribed sedative medications as risk factors for untoward events and worse patient outcomes, including brain organ dysfunction manifested as delirium and coma. The effect of sedatives on outcomes is also influenced by the depth of sedation, making it imperative to reduce total exposure to this class of medications. Juxtaposing the widespread necessity and use of sedation with the cost of acute and long-term cognitive dysfunction to patients and society, physicians must now strive to balance patients' demands and requisite for comfort with their own oath to do no harm. Fortunately, our methods of sedation and choice of medications can likely mitigate this cognitive risk. In this review, we detail the effects of perioperative and intensive care unit sedation on the development of delirium and cognitive impairment and provide an evidence-based approach towards analgesia and sedation paradigms to improve patient outcomes.

A screening, prevention, and restoration model for saving the injured brain in intensive care unit survivors

We face a profound and emerging public health problem in the form of acute and chronic brain dysfunction. This affects both young and elderly intensive care unit survivors and is altering the landscape of society. Two-thirds of intensive care unit patients develop delirium, and this is associated with longer stays, increased costs, and excess mortality. In addition, over half of intensive care unit survivors suffer a dementia-like illness that impacts their physical and cognitive functional abilities and which appears to be related to the duration of their intensive care unit delirium. A new paradigm of how intensivists handle the brain is required. We propose a three-step approach to address this emerging epidemic, which includes Screening, Prevention, and Restoration of brain function (SPR). Screening combines risk factor identification and delirium assessment using validated instruments. Prevention of acute and chronic brain dysfunction requires implementation of a core model of care that combines evidence-based practices: awakening and breathing, coordination with target-based sedation, delirium monitoring, and exercise/early mobility (ABCDE). Restoration introduces strategies of ongoing screening and treatment for intensive care unit survivors at high risk of ongoing brain dysfunction. This practical system applying many evidence-based concepts incorporates personalized medicine, systems-based practice, and continuing research and development toward improving acute and chronic cognitive outcomes.

Closed-loop coadministration of propofol and remifentanil guided by bispectral index: a randomized multicenter study

BACKGROUND

We have developed a proportional-integral-derivative controller allowing the closed-loop coadministration of propofol and remifentanil, guided by a Bispectral Index (BIS) monitor, during induction and maintenance of general anesthesia. The controller was compared with manual target-controlled infusion.

METHODS

In a multicenter study, 196 surgical patients were randomly assigned to dual closed-loop or manual administration of propofol and remifentanil. Comparison between groups was evaluated by calculating a global score that characterized the overall performance of the controller including the percentage of adequate anesthesia, defined as BIS between 40 and 60, the median absolute performance error, and wobble. Secondary outcomes included occurrence of burst suppression ratio, time to tracheal extubation, and drug consumption.

RESULTS

Eighty-three patients assigned to dual-loop control and 84 patients assigned to manual control completed the study. The global score and the percentage of time with BIS between 40 and 60 were better in the dual-loop group (26 ± 11 vs 43 ± 40, P < 0.0001; 82% ± 12% vs 71% ± 19%, P < 0.0001). Overshoot (BIS <40), undershoot (BIS >60), and burst suppression ratio were all significantly less common in the dual-loop group. Modifications to the propofol and remifentanil infusions were more frequent, and adjustments smaller in the dual-loop group. Remifentanil consumption was greater (0.22 ± 0.07 vs 0.16 ± 0.07 μg · kg(-1) · min(-1); P < 0.0001) and the speed to tracheal extubation was shorter (10 ± 4 vs 11 ± 5 minutes; P = 0.02) in the dual-loop group.

CONCLUSION

The controller allows the automated delivery of propofol and remifentanil and maintains BIS values in predetermined boundaries during general anesthesia better than manual administration.

Processed electroencephalogram in depth of anesthesia monitoring

PURPOSE OF REVIEW

We critically review the principles underlying processed electroencephalogram (EEG) monitors and recent studies validating their use in monitoring anesthetic depth.

RECENT FINDINGS

Depth of anesthesia is a theoretical construct to conceptualize anesthetic effects on the central nervous system as discrete or continuous phases or states. Clinical signs for assessing anesthetic depth are currently being supplemented by brain monitors. Their use may help to prevent insufficient anesthesia, which can lead to intraoperative awareness with recall, as well as anesthetic overdose, which may be associated with adverse events. Commercial and open-source brain monitoring indices are computed from frequency, entropy, or information theoretic analysis of the spontaneous or evoked EEG. These techniques are undergoing refinement to determine the best method for titrating anesthetics. Future depth-of-anesthesia monitors will benefit from current work aimed at correlating anesthetic effects to alterations in specific neural circuits.

SUMMARY

Current processed EEG monitors are limited by their calibration range and the interpatient variability in their dose-response curves. The next generation of depth-of-anesthesia monitors will require a greater understanding of the transformations of cortical and subcortical activity into EEG signals, the effects of anesthetics at a systems level, and the neural correlates of consciousness.

Sedation improves early outcome in severely septic Sprague Dawley rats

INTRODUCTION

Sepsis, a systemic inflammatory response to infective etiologies, has a high mortality rate that is linked both to excess cytokine activity and apoptosis of critical immune cells. Dexmedetomidine has recently been shown to improve outcome in a septic cohort of patients when compared to patients randomized to a benzodiazepine-based sedative regimen. We sought to compare the effects of dexmedetomidine and midazolam, at equi-sedative doses, on inflammation and apoptosis in an animal model of severe sepsis.

METHODS

After central venous access, Sprague Dawley rats underwent cecal ligation and intestinal puncture (CLIP) with an 18 G needle without antibiotic cover and received either saline, or an infusion of comparable volume of saline containing midazolam (0.6 mg.kg-1.h-1) or dexmedetomidine (5 ug.kg-1.h-1) for 8 hours. Following baseline measurements and CLIP, blood was sampled for cytokine measurement (tumour necrosis factor (TNF)-alpha and interleukin (IL)-6; n = 4-6 per group) at 2, 4 and 5 hours, and animal mortality rate (MR) was monitored (n = 10 per group) every 2 hours until 2 hours had elapsed. In addition, spleens were harvested and apoptosis was assessed by immunoblotting (n = 4 per group).

RESULTS

The 24 hour MR in CLIP animals (90%) was significantly reduced by sedative doses of either dexmedetomidine (MR = 20%) or midazolam (MR = 30%). While both sedatives reduced systemic levels of the inflammatory cytokine TNF-alpha (P < 0.05); only dexmedetomidine reduced the IL-6 response to CLIP, though this narrowly missed achieving significance (P = 0.05). Dexmedetomidine reduced splenic caspase-3 expression (P < 0.05), a marker of apoptosis, when compared to either midazolam or saline.

CONCLUSIONS

Sedation with midazolam and dexmedetomidine both improve outcome in polymicrobial severely septic rats. Possible benefits conveyed by one sedative regimen over another may become evident over a more prolonged time-course as both IL-6 and apoptosis were reduced by dexmedetomidine but not midazolam. Further studies are required to evaluate this hypothesis.