Entropy and bispectral index for assessment of sedation, analgesia and the effects of unpleasant stimuli in critically ill patients: an observational study

Abstract

Introduction Sedative and analgesic drugs are frequently used in critically ill patients. Their overuse may prolong mechanical ventilation and length of stay in the intensive care unit. Guidelines recommend use of sedation protocols that include sedation scores and trials of sedation cessation to minimize drug use. We evaluated processed electroencephalography (response and state entropy and bispectral index) as an adjunct to monitoring effects of commonly used sedative and analgesic drugs and intratracheal suctioning. Methods Electrodes for monitoring bispectral index and entropy were placed on the foreheads of 44 critically ill patients requiring mechanical ventilation and who previously had no brain dysfunction. Sedation was targeted individually using the Ramsay Sedation Scale, recorded every 2 hours or more frequently. Use of and indications for sedative and analgesic drugs and intratracheal suctioning were recorded manually and using a camera. At the end of the study, processed electroencephalographical and haemodynamic variables collected before and after each drug application and tracheal suctioning were analyzed. Ramsay score was used for comparison with processed electroencephalography when assessed within 15 minutes of an intervention. Results The indications for boli of sedative drugs exhibited statistically significant, albeit clinically irrelevant, differences in terms of their association with processed electroencephalographical parameters. Electroencephalographical variables decreased significantly after bolus, but a specific pattern in electroencephalographical variables before drug administration was not identified. The same was true for opiate administration. At both 30 minutes and 2 minutes before intratracheal suctioning, there was no difference in electroencephalographical or clinical signs in patients who had or had not received drugs 10 minutes before suctioning. Among patients who received drugs, electroencephalographical parameters returned to baseline more rapidly. In those cases in which Ramsay score was assessed before the event, processed electroencephalography exhibited high variation. Conclusions Unpleasant or painful stimuli and sedative and analgesic drugs are associated with significant changes in processed electroencephalographical parameters. However, clinical indications for drug administration were not reflected by these electroencephalographical parameters, and barely by sedation level before drug administration or tracheal suction. This precludes incorporation of entropy and bispectral index as target variables for sedation and analgesia protocols in critically ill patients.

Clinical Practice Guidelines for the Management of Pain, Agitation, and Delirium in Adult Patients in the Intensive Care Unit

“…(244,248,258,(265)(266)(267)(268)(269)(270)(271)(272)(273)(274)(275)(276)(277)(278)(279). Additional testing of the remaining scales is needed to better assess their reliability and validity in determining depth of sedation in critically ill patients.…”

Distancing sedation in end-of-life care from physician-assisted suicide and euthanasia

“…(30) These fi ndings are further validated by data suggesting that even patients in persistent vegetative states and minimally conscious states manifest variations in consciousness levels when studied using positron emission tomography-computed tomography and electroencephalograms. (30,(37)(38)(39)(40) Attempting to establish an irreversible loss of consciousness, much less a stable level of unconsciousness required for the determination of brain death, becomes technically diffi cult. (24,(34)(35)(36)(37)(38)(39)(40)(41)(42)(43) This is particularly so when changes in pharmacokinetics and effi cacy of medications used in the treatment of conditions such as delirium, epilepsy, schizophrenia and pain can affect levels of sedations.…”

“…(30,(37)(38)(39)(40) Attempting to establish an irreversible loss of consciousness, much less a stable level of unconsciousness required for the determination of brain death, becomes technically diffi cult. (24,(34)(35)(36)(37)(38)(39)(40)(41)(42)(43) This is particularly so when changes in pharmacokinetics and effi cacy of medications used in the treatment of conditions such as delirium, epilepsy, schizophrenia and pain can affect levels of sedations. Therefore, there is no reason to overturn the Academy of Medical Royal Colleges' 2008 Code of Practice for the Diagnosis and Confi rmation of Death, which states that "the definition of death should be regarded as the irreversible loss of the capacity for consciousness, combined with irreversible loss of the capacity to breathe."…”

Assessment and detection of pain in noncommunicative severely brain-injured patients

“…However, additional paramedical tools need to be developed in order to help clinicians in improving its detection. Recently, Haenggi and coworkers evaluated electroencephalographic (EEG) parameters as an adjunct to monitoring the effects of commonly used sedative and analgesic drugs and intratracheal suctioning in critically ill patients [40]. According to their results, painful stimuli and sedative and analgesic drugs are associated with significant changes in EEG parameters, suggesting that it could be integrated to pain management.…”