Intensive Care Unit Sedation Practices at a Large, Tertiary Academic Center

Background Sedatives are frequently administered in an ICU and are often dependent on patient population and ICU type. These differences may affect patient-centered outcomes. Objective Our primary objective was to identify differences in sedation practice among three different ICU types at an academic medical center. Methods This was a retrospective cross-sectional study of adult patients (≥18 years) requiring a continuous sedative for ≥6 h and admitted to a medical ICU, surgical ICU, and medical/surgical ICU at a single academic medical center in Rochester Minnesota from June 1, 2018 to May 31, 2020. We extracted baseline characteristics; sedative type, dose, and duration; concomitant therapies; and patient outcomes. Summary statistics are presented. Results A total of 2154 patients met our study criteria (1010 from medical ICU, 539 from surgical ICU, 605 from medical/surgical ICU). Propofol was the most frequently used sedative in all ICU settings (74.1% in medical ICU, 53.8% in surgical ICU, 68.9% in medical/surgical ICU, and 67.5% in all ICUs). The mortality rate was highest in the medical/surgical ICU (40.2% in medical ICU, 26.0% in surgical ICU, 40.7% in medical/surgical ICU, and 36.8% in all ICUs). 90.7% of all patients required mechanical ventilation (92.9% in medical ICU, 88.5% in surgical ICU, and 89.1% in medical/surgical ICU). Overall, patients spent more time in light sedation than deep sedation, 75% versus 10.3%, during their ICU admission. Patients in the medical ICU spent a greater proportion of time positive for delirium than the other ICU settings (35.7% in medical ICU, 9.8% in surgical ICU, and 20% in medical/surgical ICU). Similar amounts of opioids (morphine milligram equivalents) were used during the continuous sedative infusion between the three settings. Conclusions We observed that patients in the medical ICU spent more time deeply sedated with multiple agents which was associated with a higher proportion of delirium.

The Effect of Light Sedation with Midazolam on Functional Connectivity of the Dorsal Attention Network

Altered connectivity within and between the resting-state networks (RSNs) brought about by anesthetics that induce altered consciousness remains incompletely understood. It is known that the dorsal attention network (DAN) and its anticorrelations with other RSNs have been implicated in consciousness. However, the role of DAN-related functional patterns in drug-induced sedative effects is less clear. In the current study, we investigated altered functional connectivity of the DAN during midazolam-induced light sedation. In a placebo-controlled and within-subjects experimental study, fourteen healthy volunteers received midazolam or saline with a 1-week interval. Resting-state fMRI data were acquired before and after intravenous drug administration. A multiple region of interest-driven analysis was employed to investigate connectivity within and between RSNs. It was found that functional connectivity was significantly decreased by midazolam injection in two regions located in the left inferior parietal lobule and the left middle temporal area within the DAN as compared with the saline condition. We also identified three clusters in anticorrelation between the DAN and other RSNs for the interaction effect, which included the left medial prefrontal cortex, the right superior temporal gyrus, and the right superior frontal gyrus. Connectivity between all regions and DAN was significantly decreased by midazolam injection. The sensorimotor network was minimally affected. Midazolam decreased functional connectivity of the dorsal attention network. These findings advance the understanding of the neural mechanism of sedation, and such functional patterns might have clinical implications in other medical conditions related to patients with cognitive impairment.

Sedative and Immunosuppressive Effects of Dexmedetomidine in Transplantation

Dexmedetomidine, an α2-adrenergic receptor agonist, is used as an anti-anxiety medication. It exerts a cholinergic effect, thereby reducing the release of tumor necrosis factor alpha (TNF-α). We hypothesized that the use of dexmedetomidine as a sedative agent in transplantation would also protect allografts. We examined our patients who underwent living donor liver transplantation. Subsequently, we generated a series of mouse models to investigate the effect of dexmedetomidine on sedation-based tolerance post transplantation. A total of 49 liver recipients were enrolled in this study, of which 23 (47%) were administered dexmedetomidine through 24 h infusion on postoperative day 1. A trend toward the improvement of hepatocyte injury along with better liver function was observed in the dexmedetomidine-treated group during the first postoperative week. In animal models, dexmedetomidine inhibited the proliferation of CD4+ and CD8+ T cells and TNF-α production in a dose-dependent manner. We used dexmedetomidine to treat skin-transplanted mice and observed a significantly prolonged graft survival in mice that were administered a higher dose of dexmedetomidine. Our results revealed that dexmedetomidine exerts a dual effect of sedation and immunosuppression. This light-sedation approach will not only make patients calmer in the intensive care unit but also protect allografts from injury.

Maclura tinctoria Extracts: In Vitro Antibacterial Activity against Aeromonas hydrophila and Sedative Effect in Rhamdia quelen

Maclura tinctoria is a tree species native from Brazil and rich in phenolic compounds. Since plant antibacterial activity is highly associated with phenolic compound concentration, we aim to evaluate the in vitro antimicrobial activity of different extracts against fish pathogenic bacteria. In addition, some phenolic compounds have central depressant effects and can be useful in aquaculture due to possible sedative and/or anesthetic effects. Four M. tinctoria extracts were extracted separately with ethanol; leaves (LE), bark (BE), heartwood (HE), and the sapwood (SE). In vitro antimicrobial activity was tested against Aeromonas strains at concentrations of 6400 to 3.125 μg/mL. The sedative effect was evaluated for 24 h with 30 and 100 mg/L concentrations. Chemical composition was analyzed by HPLC-DAD-MS. The HE extract had the best MIC (400 µg/mL) and MBC (800 µg/mL) compared to the LE, BE, and SE extracts. LE extract induced deep sedation and the BE, SE, and HE extracts induced light sedation. Additionally, BE, SE, and HE induced a normal behavior without side effects. Polyphenolic compounds with antimicrobial activity and sedative effects were identified mainly in HE. Thus, HE extract is safe and can be used as a sedative for silver catfish.

Communicating with Mechanically Ventilated Patients Who Are Awake. A Qualitative Study on the Experience of Critical Care Nurses in Cyprus during the COVID-19 Pandemic.

Background: Modern protocols for light sedation in combination with the increased turnover of COVID-19 infected patients hospitalized in Intensive Care Units (ICUs) have increased the number of patients who are mechanically ventilated and awake. Nurses require specific skills to care for this vulnerable group of patients. At the same time, nurses report feeling inadequate and frustrated when they attempt to establish communication with mechanically ventilated, conscious patients. Methods: The purpose of this study was to explore nurses’ experiences taking care of conscious, intubated patients in the intensive care unit. The research questions aimed to identify i. the strategies that nurses use for communicating with patients, and ii. the barriers in communication between nurses and patients. This study employed a qualitative design. Data were collected using semi-structured interviews with 14 intensive care nurses working at ICUs in four different hospitals of Cyprus. The data were analyzed by applying thematic analysis.Results: We identified several strategies of unaided (movements -lips, hands, legs- facial expressions, gestures, touching) and aided forms of communication (pen and paper, boards, tablets, mobiles) used by nurses to communicate with patients. Additionally, barriers in communication were reported by participating nurses mainly pertaining to patients’, nurses’ characteristics and the ICU environment. The health protocols imposed by the pandemic added more barriers in the communication between nurses and patients mostly related to the use of protective health equipment.Conclusions: The results of this study, combined with those of others in different countries, point to the difficulties nurses face when trying to communicate with conscious patients during mechanical ventilation. It appears that the complex communication needs of this group of patients are not being met mainly due to the lack of nurses’ training and of appropriate equipment to facilitate alternative and augmentative communication. Our study is amongst the first to add that the protective health protocols due to the pandemic imposed further communication barriers. Undoubtedly, the recognition of such an important issue creates an urgent need to educate nurses in alternative ways of communication with mechanically ventilated, conscious patients during their ICU stay.

Evaluation of Dexmedetomidine Dosing in Obese Critically Ill Patients

Background: Dexmedetomidine is a highly selective α2-adrenoreceptor agonist that produces dose-dependent sedation, anxiolysis, and analgesia without respiratory depression. Due to these ideal sedative properties, there has been increased interest in utilizing dexmedetomidine as a first-line sedative for critically ill patients requiring light sedation. Objective: To evaluate the ability to achieve goal intensive care unit (ICU) sedation before and after an institutional change of dosing from actual (ABW) to adjusted (AdjBW) body weight in obese patients on dexmedetomidine. Methods: This study included patients ≥ 18 years old, admitted to a surgical or medical ICU, required dexmedetomidine for at least 8 hours as a single continuous infusion sedative, and weighed ≥ 120% of ideal body weight. Percentage of RASS measurements within goal range (−1 to +1) during the first 48 hours after initiation of dexmedetomidine as the sole sedative agent or until discontinuation dosed on ABW compared to AdjBW was evaluated. Results: 100 patients were included in the ABW cohort and 100 in the AdjBW cohort. The median dosing weight was significantly higher in the ABW group (95.9 [78.9-119.5] vs 82.2 [72.1-89.8] kg; p = 0.001). There was no statistical difference in percent of RASS measurements in goal range (61.5% vs 69.6%, p = 0.267) in patients that received dexmedetomidine dosed based on ABW versus AdjBW. Conclusion: Dosing dexmedetomidine using AdjBW in obese critically ill patients for ongoing ICU sedation resulted in no statistical difference in the percent of RASS measurements within goal when compared to ABW dosing. Further studies are warranted.

Depth of sedation with dexmedetomidine modulates cortical excitability non-linearly

Background: Cortical excitability changes across conscious states, being higher in unconsciousness compared to normal wakefulness. Anaesthesia offers controlled manipulation to investigate conscious processes and underlying brain dynamics. Among commonly used anaesthetic agents, dexmedetomidine (DEX) effects are not completely known. In this study, we investigated cortical excitability as a function of DEX sedation depth. Methods: Transcranial magnetic stimulation coupled with electroencephalography was recorded in 20 healthy subjects undergoing DEX sedation in four conditions (baseline, light sedation, deep sedation, recovery). Frontal and parietal cortices were stimulated using a neuronavigation system. Cortical excitability was inferred by slope, amplitude, positive and negative peak latencies of the first component (0-30 ms) of the TMS-evoked potential. Four Generalized Linear Mixed Models (GLMM) were used to test the effect of condition and brain region over cortical excitability. Results: Dexmedetomidine modulated amplitude (P<0.001), slope (P=0.0001) and positive peak (P=0.042), while the targeted brain region affected amplitude (P<0.001), slope (P<0.001), and negative peak (P=0.001). The interaction between dexmedetomidine and region had an effect over amplitude (P=0.004), and slope (P=0.009) such that cortical excitability was higher during all conditions where DEX was present as compared to the baseline. Conclusions: Cortical excitability changes non-linearly as a function of the depth of DEX sedation, with a paradoxical non dose-dependent increase. The effect is region-specific, being present in the frontal but not in the parietal region. Future research should extend the current results with other anaesthetics to better understand the link between cortical excitability and depth of sedation.

Midazolam and Ketamine Produce Distinct Neural Changes in Memory, Pain, and Fear Networks during Pain

Background Despite the well-known clinical effects of midazolam and ketamine, including sedation and memory impairment, the neural mechanisms of these distinct drugs in humans are incompletely understood. The authors hypothesized that both drugs would decrease recollection memory, task-related brain activity, and long-range connectivity between components of the brain systems for memory encoding, pain processing, and fear learning. Methods In this randomized within-subject crossover study of 26 healthy adults, the authors used behavioral measures and functional magnetic resonance imaging to study these two anesthetics, at sedative doses, in an experimental memory paradigm using periodic pain. The primary outcome, recollection memory performance, was quantified with d′ (a difference of z scores between successful recognition versus false identifications). Secondary outcomes were familiarity memory performance, serial task response times, task-related brain responses, and underlying brain connectivity from 17 preselected anatomical seed regions. All measures were determined under saline and steady-state concentrations of the drugs. Results Recollection memory was reduced under midazolam (median [95% CI], d′ = 0.73 [0.43 to 1.02]) compared with saline (d′ = 1.78 [1.61 to 1.96]) and ketamine (d′ = 1.55 [1.12 to 1.97]; P &lt; 0.0001). Task-related brain activity was detected under saline in areas involved in memory, pain, and fear, particularly the hippocampus, insula, and amygdala. Compared with saline, midazolam increased functional connectivity to 20 brain areas and decreased to 8, from seed regions in the precuneus, posterior cingulate, and left insula. Compared with saline, ketamine decreased connectivity to 17 brain areas and increased to 2, from 8 seed regions including the hippocampus, parahippocampus, amygdala, and anterior and primary somatosensory cortex. Conclusions Painful stimulation during light sedation with midazolam, but not ketamine, can be accompanied by increased coherence in brain connectivity, even though details are less likely to be recollected as explicit memories. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New