Brain connectivity under light sedation with midazolam and ketamine during task performance and the periodic experience of pain: Examining concordance between different approaches for seed-based connectivity analysis.

This work focused on functional connectivity changes under midazolam and ketamine sedation during performance of a memory task, with the periodic experience of pain. To maximize ability to compare to previous and future work, we performed secondary region of interest (ROI)-to-ROI functional connectivity analyses on these data, using two granularities of scale for ROIs. These findings are compared to the results of a previous seed-to-voxel analysis methodology, employed in the primary analysis. Healthy adult volunteers participated in this randomized crossover 3 T functional MRI study under no drug, followed by subanesthetic doses of midazolam or ketamine achieving minimal sedation. Periodic painful stimulation was delivered while subjects repeatedly performed a memory-encoding task. Atlas-based and network-level ROIs were used from within Conn Toolbox (ver 18). Timing of experimental task events was regressed from the data to assess drug-induced changes in background connectivity, using ROI-to-ROI methodology. Compared to saline, ROI-to-ROI connectivity changes under ketamine did not survive correction for multiple comparisons, thus data presented is from 16 subjects in a paired analysis between saline and midazolam. In both ROI-to-ROI analyses, the predominant direction of change was towards increased connectivity under midazolam, compared to saline. These connectivity increases occurred between functionally-distinct brain areas, with a posterior-predominant spatial distribution that included many long-range connectivity changes. During performance of an experimental task that involved periodic painful stimulation, compared to saline, low-dose midazolam was associated with robust increases in functional connectivity. This finding was concordant across different seed-based analyses for midazolam, but not ketamine. The neuroimaging drug trial from which this data was drawn was pre-registered (NCT-02515890) prior to enrollment of the first subject.

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 < 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.

A review of peripheral nerve blocks for cesarean delivery analgesia.

Peripheral nerve blocks have a unique role in postcesarean delivery multimodal analgesia regimens. In this review article, options for peripheral nerve blocks for cesarean delivery analgesia will be reviewed, specifically paravertebral, transversus abdominis plane, quadratus lumborum, iliohypogastric and ilioinguinal, erector spinae, and continuous wound infiltration blocks. Anatomy, existing literature evidence, and specific areas in need of future research will be assessed. Considerations for local anesthetic toxicity, and for informed consent for these modalities in the context of emergency cesarean deliveries, will be presented.

Maternal Mirror Syndrome Masquerading as Congestive Heart Failure: A Case Report.

Mirror syndrome is a rare pregnancy complication, life-threatening to mother and fetus. Increasing survival rates of congenital heart disease into reproductive age mean that complications like Mirror syndrome in this population may be more challenging to diagnose, given overlapping signs of edema in cases of heart failure exacerbation. We report a case of a pregnant woman with a history of unspecified congenital heart disease, presenting with swelling and distension, with diagnostic findings not consistent with preeclampsia. Her course was complicated by dyspnea, oliguria, and fetal hydrops. A cesarean delivery under neuraxial anesthesia was performed. We review the clinical manifestations of Mirror syndrome and discuss anesthetic and obstetric management considerations for this condition.

Perianesthetic and Anesthesia-Related Mortality in a Southeastern United States Population: A Longitudinal Review of a Prospectively Collected Quality Assurance Data Base.

BACKGROUND: Perianesthetic mortality (death occurring within 48 hours of an anesthetic) continues to vary widely depending on the study population examined. The authors study in a private practice physician group that covers multiple anesthetizing locations in the Southeastern United States. This group has in place a robust quality assurance (QA) database to follow all patients undergoing anesthesia. With this study, we estimate the incidence of anesthesia-related and perianesthetic mortality in this QA database. METHODS: Following institutional review board approval, data from 2011 to 2016 were obtained from the QA database of a large, community-based anesthesiology group practice. The physician practice covers 233 anesthetizing locations across 20 facilities in 2 US states. All detected cases of perianesthetic death were extracted from the database and compared to the patients' electronic medical record. These cases were further examined by a committee of 3 anesthesiologists to determine whether the death was anesthesia related (a perioperative death solely attributable to either the anesthesia provider or anesthetic technique), anesthetic contributory (a perioperative death in which anesthesia role could not be entirely excluded), or not due to anesthesia. RESULTS: A total of 785,467 anesthesia procedures were examined from the study period. A total of 592 cases of perianesthetic deaths were detected, giving an overall death rate of 75.37 in 100,000 cases (95% CI, 69.5-81.7). Mortality judged to be anesthesia related was found in 4 cases, giving a mortality rate of 0.509 in 100,000 (95% CI, 0.198-1.31). Mortality judged to be anesthesia contributory were found in 18 cases, giving a mortality of 2.29 in 100,000 patients (95% CI, 1.45-3.7). A total of 570 cases were judged to be nonanesthesia related, giving an incidence of 72.6 per 100,000 anesthetics (95% CI, 69.3-75.7). CONCLUSIONS: In a large, comprehensive database representing the full range of anesthesia practices and locations in the Southeastern United States, the rate of perianesthestic death was 0.509 in 100,000 (95% CI, 0.198-1.31). Future in-depth analysis of the epidemiology of perianesthetic deaths will be reported in later studies.