Continuous nervous system monitoring, EEG, the bispectral index, and neuromuscular transmission

The Impact of Bispectral Index Monitoring on Sedation Administration in Mechanically Ventilated Patients

The aim of this prospective randomised controlled trial was to assess the effectiveness of the Bispectral Index (BIS) monitor in supporting clinical sedation management decisions in mechanically ventilated intensive care unit patients. Fifty adult mechanically ventilated surgical and general intensive care unit patients receiving sedative infusions of morphine and midazolam were randomly allocated to receive BIS monitoring (n=25) or standard sedation management (n=25). In the BIS group, sedation was titrated to maintain a BIS value of greater than 70. In the standard management group, sedative needs were titrated based on subjective assessment and clinical signs.

There was no statistically significant difference in the amount of sedation administered (morphine P =0.67 and midazolam P =0.85). However, there was a statistically significant difference in sedation administration over time. Patients in the BIS group received increasing amounts of sedation over time whilst those in the control group received decreasing amounts of sedation over time. The same inverse relationship existed for both sedative agents (morphine P=0.005, midazolam P=0.03). Duration of mechanical ventilation was comparable in the two groups. We conclude that the use of BIS monitoring did not reduce the amount of sedation used, the length of mechanical ventilation time or the length of ICU stay.

Effects of sedation on subjective perception of pain intensity and autonomic nervous responses to pain: A preliminary study

Rather than relying solely on subjective pain evaluation using means such as the visual analogue scale (VAS), in clinical situations it is possible to observe evoked responses of the autonomic nervous system (ANS) as objective indicators. Few studies, however, have reported these relationships under finely controlled sedation. 16 healthy male participants were administrated in intravenous sedation with either propofol or midazolam randomly. We initially determined, using pharmacokinetic simulation, the effect-site concentration (Ce) of anaesthetic at loss of response to verbal command and eyelash reflex (Ce-LOR). Then subsequently adjusted Ce to 75%, 50%, and 25% of Ce-LOR to achieve deep, moderate, and light sedation. At awake control state and each sedation level, a noxious electrical stimulation was applied three times at the right forearm, an average pain intensity of the three stimuli was rated on a VAS (0–10). Changes in the peripheral perfusion index measured by oximetry were used as an indicator of ANS response. We analyzed the influence of sedation level on VAS and ANS responses compared to the awake control state. While ANS responses were similar in all conditions, VAS was statistically significantly lower in moderate (5.6±0.6, p <0.005) or deep (5.3±0.6, p <0.001) sedation than in the awake state (7.2±0.4). This study revealed that even when the ANS responds similarly to the same stimulation, subjective pain perception is attenuated by sedation. A cerebral mechanism other than that of the brainstem might determine subjective pain intensity.

Evidence and consensus based guideline for the management of delirium, analgesia, and sedation in intensive care medicine. Revision 2015 (DAS-Guideline 2015) - short version

In 2010, under the guidance of the DGAI (German Society of Anaesthesiology and Intensive Care Medicine) and DIVI (German Interdisciplinary Association for Intensive Care and Emergency Medicine), twelve German medical societies published the “Evidence- and Consensus-based Guidelines on the Management of Analgesia, Sedation and Delirium in Intensive Care”. Since then, several new studies and publications have considerably increased the body of evidence, including the new recommendations from the American College of Critical Care Medicine (ACCM) in conjunction with Society of Critical Care Medicine (SCCM) and American Society of Health-System Pharmacists (ASHP) from 2013. For this update, a major restructuring and extension of the guidelines were needed in order to cover new aspects of treatment, such as sleep and anxiety management. The literature was systematically searched and evaluated using the criteria of the Oxford Center of Evidence Based Medicine. The body of evidence used to formulate these recommendations was reviewed and approved by representatives of 17 national societies. Three grades of recommendation were used as follows: Grade “A” (strong recommendation), Grade “B” (recommendation) and Grade “0” (open recommendation). The result is a comprehensive, interdisciplinary, evidence and consensus-based set of level 3 guidelines. This publication was designed for all ICU professionals, and takes into account all critically ill patient populations. It represents a guide to symptom-oriented prevention, diagnosis, and treatment of delirium, anxiety, stress, and protocol-based analgesia, sedation, and sleep-management in intensive care medicine.

Advances in cerebral monitoring for the patient with traumatic brain injury

A brief overview of the most common invasive and noninvasive monitoring tools collectively referred to using the term "multimodal monitoring" is provided. Caring for the critically ill patient with traumatic brain injury requires careful monitoring to prevent or reduce secondary brain injury. Concurrent to the growth of the subspecialty of neurocritical care, there has been a concerted effort to discover novel mechanisms to monitor the physiology of brain injury. The past 2 decades have witnessed an exponential growth in neurologic monitoring in terms of intracranial pressure, blood flow, metabolism, oxygenation, advanced neuroimaging, and electrophysiology.

A pilot study of cerebral and haemodynamic physiological changes during sedation with dexmedetomidine or propofol in patients with acute brain injury

Sedation for the mechanically-ventilated, brain-injured patient remains challenging. The purpose of this pilot study was to compare the cerebral physiologic effects of sedation with propofol versus dexmedetomidine in mechanically-ventilated, brain-injured patients. Using a randomised, crossover, unblinded clinical trial, we enrolled patients with severe brain injury (Glasgow Coma Score ≤8) from traumatic injury, subarachnoid haemorrhage or intracerebral haemorrhage undergoing multimodal monitoring (intracranial pressure, brain temperature, oximetry and microdialysis). Patients received an infusion of either propofol or dexmedetomidine for six hours and then a crossover for the subsequent six hours after sufficient washout/in. Clinical and physiological measurements were recorded hourly. In eight patients, (four traumatic injury, three subarachnoid haemorrhage and one intracerebral haemorrhage), the mean dose of propofol used was 25.5 µg/kg/minute while the mean dose of dexmedetomidine was 0.54 µg/kg/hour. All subjects were effectively sedated to a goal of Richmond Agitation Sedation Scale -2 and Bispectral Index of 50-70 throughout the study period. We did not observe any statistically significant differences between the groups in systemic or cerebral physiologic metrics. Though differences were noted in cerebral metabolic substrates (lactate/pyruvate ratio), none were statistically significant. In our pilot cohort, dexmedetomidine and propofol appear equally effective in sedating severely brain-injured patients and neither is associated with adverse physiological effects as measured by multimodal monitoring. Larger long-term studies are required to determine whether clinically favourable benefits demonstrated in the medical critical care setting also apply to this patient population.

Evidence and consensus-based German guidelines for the management of analgesia, sedation and delirium in intensive care--short version

Targeted monitoring of analgesia, sedation and delirium, as well as their appropriate management in critically ill patients is a standard of care in intensive care medicine. With the undisputed advantages of goal-oriented therapy established, there was a need to develop our own guidelines on analgesia and sedation in intensive care in Germany and these were published as 2(nd) Generation Guidelines in 2005. Through the dissemination of these guidelines in 2006, use of monitoring was shown to have improved from 8 to 51% and the use of protocol-based approaches increased to 46% (from 21%). Between 2006-2009, the existing guidelines from the DGAI (Deutsche Gesellschaft für Anästhesiologie und Intensivmedizin) and DIVI (Deutsche Interdisziplinäre Vereinigung für Intensiv- und Notfallmedizin) were developed into 3(rd) Generation Guidelines for the securing and optimization of quality of analgesia, sedation and delirium management in the intensive care unit (ICU). In collaboration with another 10 professional societies, the literature has been reviewed using the criteria of the Oxford Center of Evidence Based Medicine. Using data from 671 reference works, text, diagrams and recommendations were drawn up. In the recommendations, Grade "A" (very strong recommendation), Grade "B" (strong recommendation) and Grade "0" (open recommendation) were agreed. As a result of this process we now have an interdisciplinary and consensus-based set of 3(rd) Generation Guidelines that take into account all critically illness patient populations. The use of protocols for analgesia, sedation and treatment of delirium are repeatedly demonstrated. These guidelines offer treatment recommendations for the ICU team. The implementation of scores and protocols into routine ICU practice is necessary for their success.

Continuous noninvasive monitoring of barbiturate coma in critically ill children using the Bispectral index monitor

Introduction

Traumatic brain injury and generalized convulsive status epilepticus (GCSE) are conditions that require aggressive management. Barbiturates are used to lower intracranial pressure or to stop epileptiform activity, with the aim being to improve neurological outcome. Dosing of barbiturates is usually guided by the extent of induced burst-suppression pattern on the electroencephalogram (EEG). Dosing beyond the point of burst suppression may increase the risk for complications without offering further therapeutic benefit. For this reason, careful monitoring of EEG parameters is mandatory. A prospective study was conducted to evaluate the usefulness of the bispectral index suppression ratio for monitoring barbiturate coma.

Methods

A prospective observational pilot study was performed at a paediatric (surgical) intensive care unit, including all children with barbiturate-induced coma after traumatic brain injury or GCSE. The BIS™ (Bispectral™ index) monitor expresses a suppression ratio, which represents the percentage of epochs per minute in which the EEG was suppressed. Suppression ratios from the BIS monitor were compared with suppression ratios of full-channel EEG as assessed by quantitative visual analysis.

Results

Five patients with GCSE and three patients after traumatic brain injury (median age 11.6 years, range 4 months to 15 years) were included. In four patients the correlation between the suppression ratios of the BIS and EEG could be determined; the average correlation was 0.68. In two patients, suppression ratios were either high or low, with no intermediate values. This precluded determination of correlation values, as did the isoelectric EEG in a further two patients. In the latter patients, the mean ± standard error BIS suppression ratio was 95 ± 1.6.

Conclusion

Correlations between suppression ratios of the BIS and EEG were found to be only moderate. In particular, asymmetrical EEGs and EEGs with short bursts (less than 1 second) may result in aberrant BIS suppression ratios. The BIS monitor potentially aids monitoring of barbiturate-induced coma because it provides continuous data on EEG suppression between full EEG registrations, but it should be used with caution.

Impact of bispectral index monitoring on sedation and outcomes in critically ill adults: a case series

In situations in which clinical assessment of sedation level is compromised, such as deep sedation/analgesia with and without neuromuscular blockade (NMB), electroencephalogram-based monitoring may potentially assist in achieving balance between inadequate and excessive levels of sedation. To validate the bispectral index (BIS) for use in clinical practice, correlation and possible differences in outcome using clinical assessment versus clinical assessment augmented by electroencephalogram-based monitoring were determined. BIS monitoring was decisive in ICU care in 9 of 15 patients in this series. The most significant potential benefit was obtained in the subset of patients receiving NMB.

Consciousness, coma, and caring for the brain-injured patient

In this article, a preliminary conceptual framework is presented for exploring nursing interventions and research aimed at improving care of the unconscious brain-injured patient during the early subacute phase of brain injury. The cue-response framework presented is derived from multidisciplinary sources and has specific clinical relevance to critical care nurses caring for unconscious brain-injured patients. A key aspect of this framework is the attention focused on the timing of nursing interventions in response to how nurses interpret the physical, physiological, and secondary cues they observe when caring for comatose patients. A case exemplar is used to present one example of how this framework may be used in the clinical setting.

Refractory increased intracranial pressure in severe traumatic brain injury: barbiturate coma and bispectral index monitoring

Patients with severe traumatic brain injury resulting in increased intracranial pressure refractory to first-tier interventions challenge the critical care team. After exhausting these initial interventions, critical care practitioners may utilize barbiturate-induced coma in an attempt to reduce the intracranial pressure. Titrating appropriate levels of barbiturate is imperative. Underdosing the drug may fail to control the intracranial pressure, whereas overdosing may lead to untoward effects such as hypotension and cardiac compromise. Monitoring for a therapeutic level of barbiturate coma includes targeting drug levels and using continuous electroencephalogram monitoring, considered the gold standard. New technology, the Bispectral Index monitor, utilizes electroencephalogram principles to monitor the level of sedation and hypnosis in the critical care environment. This technology is now being considered for targeting appropriate levels of barbiturate coma.

Patients’ Recollections of Therapeutic Paralysis in the Intensive Care Unit

• Background Neuromuscular blocking agents used for therapeutic purposes, such as facilitating mechanical ventilation and relieving life-threatening agitation, paralyze patients but leave them fully conscious. Aggressive sedation or analgesia is necessary to reduce awareness, relieve fear, produce comfort, decrease anxiety, induce unconsciousness, and minimize possible complications such as posttraumatic stress syndrome. Little information is available on the extent to which patients experience awareness during therapeutic paralysis.

• Objectives To determine and describe the remembered experiences of critical care patients who were given neuromuscular blocking agents and sedatives and/or analgesics to facilitate mechanical ventilation, improve hemodynamic stability, and improve oxygenation.

• Methods A phenomenological approach with in-depth interviews with 11 patients was used. Data were analyzed by using the constant comparative approach.

• Results A total of 4 themes and 3 subthemes were identified. The first theme was back and forth between reality and the unreal, between life and death; the subtheme was having weird dreams. The second theme was loss of control; the 2 subthemes were (1) fighting or being tied down and (2) being scared. The third theme was almost dying, and the fourth theme was feeling cared for.

• Conclusions Patients can remember having both negative and positive experiences during neuromuscular blockade. Steps to improve the experiences of patients receiving neuromuscular blockers include improving assessment parameters, developing and using sedation/analgesia guidelines, and investing in quality improvement programs to provide assessment of awareness during therapeutic paralysis and follow-up and referral as necessary. Ways to decrease the use of neuromuscular blockers would also be useful.

Clinical Management of the Organ Donor

There is a critical mismatch between available organs for transplant and acutely or critically ill patients with end-stage organ disease. Patients who may benefit from organ transplantation far outnumber available organs. The causes for this imbalance are multiple. One cause is family refusal to donate. A second cause is nonrecognition or delay in determination of brain death. A third cause is donor loss due to profound cardiopulmonary and metabolic instability consequent to brain-stem herniation and brain death. Family refusal may be addressed by education, public awareness, as well as close attention to social, cultural and ethical issues, and optimal communication with donor families. Brain death may be consequent to traumatic brain injury, ischemic versus hemorrhagic stroke, as well as massive cerebral anoxia/ischemic following cardiac arrest. Nonrecognition or delay in brain death determination may be addressed by clinician education and frequent clinical assessment to detect early stages of brain-stem herniation refractory to aggressive measures for control of intracranial pressure. Donor loss due to profound cardiopulmonary and metabolic instability may be addressed by aggressive, mechanism-based treatment for clinical instability based on affected body system, as well as measures to support metabolic activity at the cellular and tissue level in the brain-dead organ donor. This article explores cerebral physiology related to impending brain death and catastrophic intracranial pressure elevations. In addition, physiologic consequences of brain death are correlated with affected body systems and mechanism-based therapies to support organ function pending transplantation. Ethical/legal issues are explored as related to patient autonomy and optimal family outcomes. Effective family communication, astute clinical assessment, and optimal clinical management of the organ donor are illustrated using a case study approach, highlighting the role of the advanced practice nurse in donor management.

Toward Solving the Sedation-Assessment Conundrum: Bispectral Index Monitoring and Sedation Interruption

The sedation-assessment conundrum is defined by two diametrically opposed goals: to maintain an appropriate level of sedation, and to obtain a comprehensive neurologic examination that most accurately reflects the patient's neurologic status. A case presentation leads to a discussion of over-sedation and under-sedation issues that impact the care of critically ill patients. This information is useful in understanding the many methods of assessing sedation and interpreting individualized patient responses to sedation. The use of bi-spectral index monitoring and periods of sedation interruption are discussed within the context of addressing the sedation-assessment conundrum.

Breakthroughs beckon new approaches to existing procedures

The latest technology supplements cardiac care, sedation monitoring, and infection control.