Cognitive properties of sedation agents: comparison of the effects of nitrous oxide and midazolam on memory and mood

Effects of Ketamine and Midazolam on Simultaneous EEG/fMRI Data During Working Memory Processes

Reliable measures of cognitive brain activity from functional neuroimaging techniques may provide early indications of efficacy in clinical trials. Functional magnetic resonance imaging and electroencephalography provide complementary spatiotemporal information and simultaneous recording of these two modalities can remove inter-session drug response and environment variability. We sought to assess the effects of ketamine and midazolam on simultaneous electrophysiological and hemodynamic recordings during working memory (WM) processes. Thirty participants were included in a placebo-controlled, three-way crossover design with ketamine and midazolam. Compared to placebo, ketamine administration attenuated theta power increases and alpha power decreases and midazolam attenuated low beta band decreases to increasing WM load. Additionally, ketamine caused larger blood-oxygen-dependent (BOLD) signal increases in the supplementary motor area and angular gyrus, and weaker deactivations of the default mode network (DMN), whereas no difference was found between midazolam and placebo. Ketamine administration caused positive temporal correlations between frontal-midline theta (fm-theta) power and the BOLD signal to disappear and attenuated negative correlations. However, the relationship between fm-theta and the BOLD signal from DMN areas was maintained in some participants during ketamine administration, as increasing theta strength was associated with stronger BOLD signal reductions in these areas. The presence of, and ability to manipulate, both positive and negative associations between the BOLD signal and fm-theta suggest the presence of multiple fm-theta components involved in WM processes, with ketamine administration disrupting one or more of these theta-linked WM strategies.

Comparison of dexmedetomidine with midazolam for dental surgery: A systematic review and meta-analysis

INTRODUCTION

Dexmedetomidine and midazolam have become important approaches for the sedation of dental surgery. However, the comparison of these 2 drugs for the sedation of dental surgery has not been well established. We conduct a systematic review and meta-analysis to evaluate the efficacy of dexmedetomidine versus midazolam for dental surgery.

METHODS

PubMed, Embase, and the Cochrane Central Register of Controlled Trials are searched. Randomized controlled trials (RCTs) assessing the influence of dexmedetomidine versus midazolam on dental surgery are included. Two investigators independently have searched articles, extracted data, and assessed the quality of included studies. Meta-analysis is performed using the random-effect model.

RESULTS

Five RCTs and 420 patients are included in the meta-analysis. Compared with midazolam intervention for dental surgery, dexmedetomidine intervention has similar lowest SpO2, lowest heart rate and lowest systolic blood pressure, duration of surgery, and total volume of local anesthetic, but is associated with stable and reduced lowest diastolic blood pressure.

CONCLUSIONS

Similar benefits of dexmedetomidine and midazolam intervention are observed for the sedation of dental surgery in terms of SpO2, heart rate, systolic blood pressure, and the volume of local anesthetic, but dexmedetomidine may result in more stable diastolic blood pressure.

Nitrous oxide as a putative novel dual-mechanism treatment for bipolar depression: Proof-of-concept study design and methodology

Introduction

Depressive symptoms predominate in the course of bipolar disorder (BD) and there is an urgent need to evaluate novel application of repurposed compounds that act on pre-specified treatment targets. Several lines of reasoning suggest that nitrous oxide (N₂O) is an ideal medication to study as a potential treatment and as a strategy to identify the underlying pathophysiology of bipolar depression. N₂O is a potent cerebral vasodilator and there is compelling evidence of reduced frontal cerebral blood flow (CBF; i.e. hypoperfusion) in depression. Therefore, N₂O may increase CBF and thereby improve symptoms of depression. The goal of this randomized, double-blind trial is to study the effect of a single administration of N₂O versus the active comparator midazolam on mood and CBF in adults with treatment-resistant bipolar depression.

Methods

Participants with BD-I/-II currently experiencing a major depressive episode will be randomized to one of two conditions (n = 20/group): 1) inhaled N₂O plus intravenous saline, or 2) inhaled room air plus intravenous midazolam. Montgomery-Asberg Depression Rating Scale scores will serve as the primary endpoint. CBF will be measured via arterial spin labelling magnetic resonance imaging.

Conclusions

N₂O is a potential novel treatment for bipolar depression, as it causes cerebral vasodilation. This proof-of-concept study will provide valuable information regarding the acute impact of N₂O on mood and on CBF. If N₂O proves to be efficacious in future larger-scale trials, its ubiquity, safety, low cost, and ease of use suggest that it has great potential to become a game-changing acute treatment for bipolar depression.

Memory and hippocampal architecture following short-term midazolam in western diet-treated rats

The impact of short-term benzodiazepine exposure on cognition in middle-aged or older patients is a highly debated topic among anesthesiologists, critical care physicians and public media. "Western diet" (WD) consumption is linked to impaired cognition as well. The combination of benzodiazepines with substantial exposure to WD might set the stage for increased hippocampal vulnerability for benzodiazepines leading to exaggerated cognitive impairment in the postoperative period. In this study, Fischer 344 rats were fed either WD or standard rodent diet from 5 to 10.5 months of age. Rats were exposed to midazolam or placebo two days prior to an MRI scan using Diffusional Kurtosis Imaging (DKI) to assess brain microstructural integrity, followed by behavioral testing using a water radial arm maze. Hippocampal tissue was collected to assess alterations in protein biochemistry in brain regions associated with learning and memory. Our results showed that rats exposed to the combination of midazolam and WD had significantly delayed time of learning and exhibited spatial memory impairment. Further, we observed an overall increase of kurtosis metrics in the hippocampus and increased expression of the mitochondrial protein VDAC2 in midazolam-treated rats. Our data suggest that both the short-acting benzodiazepine midazolam and WD contribute to negatively affect the brain in middle-aged rats. This study is the first application of DKI on the effects of midazolam and WD exposure, and the findings demonstrate that diffusion metrics are sensitive indicators of changes in the complexity of neurite architecture.

Does Intravenous Midazolam Dose Influence the Duration of Recovery Room Stay Following Outpatient Third Molar Surgery?

PURPOSE

To evaluate the impact of intravenous midazolam dose on the duration of recovery room stay for patients undergoing outpatient third molar surgery.

MATERIALS AND METHODS

Using a retrospective cohort study design, a sample of patients undergoing outpatient third molar surgery under intravenous sedation at Mayo Clinic from 2010 to 2014 was identified. All patients underwent extraction of all 4 third molars during a single operative procedure and the age range was limited to 14 to 29 years. The primary predictor variable was the total dose of intravenous midazolam administered during sedation. The primary outcome variable was recovery room length of stay (LOS) after completion of surgery. Multiple covariates also abstracted included patient age, gender, American Society of Anesthesiologists (ASA) score, duration of surgical procedure, complexity of surgical procedure, types and dosages of all intravenous medications administered during sedation, and volume of crystalloid fluid administered perioperatively. Univariable and multivariable models were developed to evaluate associations between the primary predictor variable and covariates relative to the primary outcome variable.

RESULTS

The study sample was composed of 2,610 patients. Mean age was 18.3 years (SD, 3.0 yr; range, 14 to 29 yr) and gender distribution was 52% female. Mean dosage of midazolam administered was 4.1 mg (SD, 1.1 mg; range, 0.5 to 10.0 mg). Variables predicting shorter LOS at multivariable analysis included older age (P < .001), male gender (P = .004), and administration of larger crystalloid fluid volumes (P < .001). Variables predicting longer LOS included higher ASA score (P < .001), administration of ketamine (P < .001), and administration of ketorolac (P < .001). The dose of midazolam administered during sedation was not found to be significantly associated with prolonged recovery room LOS in univariable or multivariable settings.

CONCLUSION

Dosage of intravenous midazolam does not appear to significantly impact the duration of recovery room stay in the prototypical patients undergoing sedation for outpatient third molar surgery.

Anti-stress effects of lemon balm-containing foods

Lemon balm (Melissa officinalis) has been used historically and contemporarily as a modulator of mood and cognitive function, with anxiolytic effects following administration of capsules, coated tablets and topical application. Following a pilot study with lemon balm extract administered as a water based drink, which confirmed absorption of rosmarinic acid effects on mood and cognitive function, we conducted two similar double-blind, placebo-controlled, crossover studies. These evaluated the mood and cognitive effects of a standardised M. officinalis preparation administered in palatable forms in a beverage and in yoghurt. In each study a cohort of healthy young adults' self-rated aspects of mood were measured before and after a multi-tasking framework (MTF) administered one hour and three hours following one of four treatments. Both active lemon balm treatments were generally associated with improvements in mood and/or cognitive performance, though there were some behavioral "costs" at other doses and these effects depended to some degree on the delivery matrix.

Escorts' knowledge of their duty of care to patients who have undergone intravenous sedation

AIM

To assess escorts' understanding of their responsibilities to the patient 24 hours following dental treatment under intravenous sedation.

STANDARDS

One hundred per cent of escorts: have been informed of their duties, have read the information sheet, expect at least a one hour appointment, identify the hazardous activities patients should avoid following sedation, travel by private transport, are aware that medications are taken as normal, should have care in place 24 hours following sedation.

METHOD

This was a prospective questionnaire-based audit. Questionnaires were handed to escorts of patients receiving treatment under intravenous sedation in Newcastle Dental Hospital sedation department.

RESULTS

Of 104 responses, 91.3% of escorts were informed about their duties and 79.8% had read the information sheet prior to the appointment. Boiling a kettle and Internet use were the most selected hazardous activities that escorts deemed safe for patients to carry out postoperatively (19.2%, 23.0%.) Private transport home was mainly used (car 73.1%, taxi 24.9%.) Following sedation, 93.3% of patients had an escort for 24 hours.

CONCLUSION

Escorts' basic knowledge fell short of the standard. Improvements are needed to ensure patient safety.

RECOMMENDATIONS

At the pre-assessment, the patient might be given an information sheet solely for the escort and encouraged to explain this to the escort. More comprehensive information listing activities hazardous to the patient 24 hours following sedation and emphasising that taking medications as normal preoperatively could be available on the treatment day. Transport information in the appointment letter might improve access. A Trust website link, a DVD and posters in the waiting room could further inform.

The value of assessing cognitive function in drug development

This paper reviews the value and utility of measuring cognitive function in the development of new medicines by reference to the most widely used automated system in clinical research. Evidence is presented from phase 1 to 3 of the nature and quality of the information that can be obtained by applying the Cognitive Drug Research computerized assessment system to ongoing clinical trials. Valuable evidence can be obtained even in the first trial in which a novel compound is administered to man. One application of such testing is to ensure that novel compounds are relatively free from cognition-impairing properties, particularly in relation to competitor products. Another is to ensure that unwanted interactions with alcohol and other medications do not occur, or, if they do, to put them in context. In many patient populations, cognitive dysfunction occurs as a result of the disease process, and newer medicines which can treat the symptoms of the disease without further impairing function can often reveal benefits as the disease-induced cognitive dysfunction is reduced. Another major application is to identify benefits for compounds designed to enhance cognitive function. Such effects can be sought in typical phase 1 trials, or a scopolamine model of the core deficits of Alzheimer's disease can be used to screen potential antidernentia drugs. Ultimately, of course, such effects can be demonstrated using properly validated and highly sensitive automated procedures in the target populations. The data presented demonstrate that the concept of independently assessing a variety of cognitive functions is crucial in helping differentiate drugs, types of dementia, and different illnesses. Such information offers a unique insight into how the alterations to various cognitive functions will manifest themselves in everyday behavior. This reveals a major limitation of scales that yield a single score, because such limited information does not permit anything but a quantitative interpretation; and the concept of "more" cognitive function or "less" is manifestly inappropriate for something as complex and diverse as the interplay between cognitive function and human behavior. Finally, the next generations of cognitive testing are described. Testing via the telephone has just been introduced and will have dramatic effects on the logistics of conducting cognitive testing in large patient trials. Testing via the Internet is not far off either, and will come fully into play as the proportion of homes connected to the Internet increases in Europe and North America. There are no sound reasons for not wishing to include cognitive function testing in the development protocol of any novel medicine.

Cognitive testing in early-phase clinical trials: Development of a rapid computerized test battery and application in a simulated Phase I study

BACKGROUND

Inclusion of cognitive assessment in Phase I trials of novel pharmaceutical agents may help identify subtle yet meaningful CNS effects early in clinical development, and lead to a greater understanding of the pharmacokinetic/pharmacodynamic relationship prior to entering pivotal late-phase trials.

AIMS

To examine issues surrounding the inclusion of a computerised cognitive test battery in Phase I clinical trials.

METHODS

A 12-minute battery of five computerized cognitive tasks was administered to 28 healthy males in a double-blind, single ascending dose study using three doses of midazolam (0.6 mg, 1.75 mg and 5.25 mg) with placebo insertion. Subjects were enrolled and assessed at two Phase I units. Statistical analyses sought to determine the sensitivity of the test battery to sedation-related cognitive dysfunction, any between-site differences in outcome, and also the effects of repeated test administration (i.e., practice or learning effects).

RESULTS

There were no significant differences in data collected between sites. All standard safety measurements were completed. No substantial technical issues were noted. No learning effects were observed on four of the five cognitive tasks. ANOVA comparing baseline to post-baseline results revealed significant cognitive deterioration on all five cognitive tasks 1 h following administration of 5.25 mg midazolam. The magnitude of these changes were very large according to conventional statistical criteria. Smaller but significant changes were observed on a subset of memory and learning tasks at 1 h post-dosing in 1.75 mg condition, and at 2 h post-dosing in the 5.25 mg condition.

CONCLUSIONS

The cognitive test battery was well tolerated by subjects and research unit staff. The tests demonstrated minimal learning effects, were unaffected by language and cultural differences between sites, and were sensitive to the sedative effects of midazolam. Inclusion of this cognitive test battery in future studies may allow identification of cognitive impairment or enhancement early in the clinical development cycle.

Cognitive testing in early phase clinical trials: outcome according to adverse event profile in a Phase I study

BACKGROUND

It has been proposed that objective cognitive testing provides additional information to that collected via adverse event (AE) recordings. However, in clinical trials of compounds with potentially negative effects on cognition, the results of cognitive testing may overlap with AE recordings.

AIMS

To examine cognitive function in subjects who do and do not report sedation-related AEs in a Phase I clinical trial.

METHODS

Five computerized cognitive tasks were administered to 28 healthy male volunteers enrolled in a simulated Phase I study using midazolam to induce sedation-related AEs and cognitive dysfunction. For each subject, the magnitude of cognitive change between pre-dose and 1 hr post-dose assessments was calculated. Group and individual level cognitive outcome was compared between subjects who did and did not report sedation-related AEs following administration of 1.75 and 5.25 mg midazolam.

RESULTS

At both doses of midazolam, cognitive dysfunction was observed in both subject groups (i.e., those who did and did not report AEs). Analysis of individual outcomes identified consistent cognitive dysfunction among subjects who reported sedation-related AEs. Further, in the 5.25 mg condition a subset of individuals (66.7%) who did not report sedation-related AEs nevertheless displayed substantial cognitive dysfunction.

CONCLUSIONS

Following administration of oral midazolam, there is a dissociation between sedation-related AE recordings and performance on computerized cognitive tests of motor function, attention, strategy use and problem solving, learning and delayed recall. Inclusion of computerized cognitive tests in early phase trials may allow identification of subtle cognitive change, beyond that which is possible by self-report and clinical observation.

New Method of Sedation in Oral Surgery

Local anesthesia, the well-known method of sedation, usually is insufficient for dental implantation and the augmentation of the alveolar ridge, because the operations last for 1 to 2 hours and patients may experience fear and strain. This article examines a new complex sedation method using ketorolac, midazolam, and a local anesthetic 4% solution of articaine hydrochloride and epinephrine (Septanest) in combination with a vasoconstrictor. This method was applied to 67 patients operated on for dental implantation with screw implants or for the alveolar ridge augmentation with biocompatible materials. The control group, which consisted of 20 patients, received local anesthesia with articaine-epinephrine only. Most of the control patients were found to have experienced fear and strain during the aforementioned surgical procedures; their blood pressure and pulse rate increased, and more than half of them experienced pain. No disorders of hemodynamics or the psychoemotional status of the patients were observed during sedation with ketorolac, midazolam, and articaine-epinephrine. Furthermore, anterograde amnesia was determined for the 80% of the patients in the test group.

A randomised crossover trial of post-operative cognitive and psychomotor recovery from benzodiazepine sedation: effects of reversal with flumazenil over a prolonged recovery period

OBJECTIVE

To study the post-operative cognitive and psychomotor recovery from midazolam conscious sedation, after reversal with the benzodiazepine antagonist flumazenil over a prolonged recovery period.

DESIGN

A prospective, double-blind, randomised, crossover trial.

SETTING

Out-patient Sedation Department, Newcastle Dental Hospital and School

METHOD

Eighteen patients, ASA I or II, received midazolam on two separate occasions to undergo equivalent dental treatment. Following treatment patients were reversed with intravenous flumazenil or saline (placebo) at alternate appointments. Assessment of mood and cognitive function was undertaken using a highly sensitive and specific computerised battery of cognitive tests administered by telephone. Cognitive and psychomotor tests were administered prior to sedation and every hour for 6 hours post reversal.

RESULTS

Results indicated no significant effect of flumazenil on simple reaction time and choice reaction time but did show a trend of reversing the effects of midazolam on numeric working memory and word recognition.

CONCLUSION

The cognitive and psychomotor effects of the sedation were not fully reversed by flumazenil. Cognitive impairments were still present up to 6 hours post-reversal, despite patients appearing clinically more alert. This has important implications for treatment protocols and discharge instructions.

Attenuation of laboratory-induced stress in humans after acute administration of Melissa officinalis (Lemon Balm)

OBJECTIVE

Melissa officinalis (lemon balm) is contemporaneously used as a mild sedative and/or calming agent. Although recent research has demonstrated modulation of mood in keeping with these roles, no studies to date have directly investigated the effects of this herbal medication on laboratory-induced psychological stress.

METHODS

In this double-blind, placebo-controlled, randomized, balanced crossover experiment, 18 healthy volunteers received two separate single doses of a standardized M. officinalis extract (300 mg, 600 mg) and a placebo, on separate days separated by a 7-day washout period. Modulation of mood was assessed during predose and 1-hour postdose completions of a 20-minute version of the Defined Intensity Stressor Simulation (DISS) battery. Cognitive performance on the four concurrent tasks of the battery was also assessed.

RESULTS

The results showed that the 600-mg dose of Melissa ameliorated the negative mood effects of the DISS, with significantly increased self-ratings of calmness and reduced self-ratings of alertness. In addition, a significant increase in the speed of mathematical processing, with no reduction in accuracy, was observed after ingestion of the 300-mg dose.

CONCLUSION

These results suggest that the potential for M. officinalis to mitigate the effects of stress deserves further investigation.

Mechanisms of action of midazolam on expression of contextual fear in rats

BACKGROUND

Midazolam may suppress conditioned fear after an aversive event by disrupting the memory trace formed during conditioning, by altering the emotional part of the aversive event, or by the combination of both effects. The purpose of the present study was to determine whether affective-related processes contribute to the amnesic-like effects of midazolam on aversive events.

METHODS

The effects of acute administration of low doses of midazolam (0.37-3 mg kg(-1)) on fear conditioning (association between a neutral context and an aversive stimulus) and on innate anxiety in fearful surroundings were examined in rats. The effect of midazolam on the deleterious consequences of pre-exposure to the context (a non-aversive event) for subsequent fear conditioning was then compared with its effect on fear conditioning. The role of midazolam as an affective context was assessed by performing the testing phase under midazolam. Possible locomotor impairment or long-term effects of midazolam were controlled in additional experiments.

RESULTS

Midazolam reduced both contextual fear conditioning and spontaneous fear. The deleterious effect of midazolam on pre-exposure to the context was of the same magnitude as its effect on the acquisition phase of fear conditioning. The effects of midazolam on both pre-exposure to the context and fear conditioning were unchanged when rats received a second injection of midazolam before the retention phase.

CONCLUSIONS

Low doses of midazolam that do not impair locomotion suppress conditioned fear to the context by acting on memory processes rather than on affective or anxiolytic processes.

A randomised, controlled trial of cognitive and psychomotor recovery from midazolam sedation following reversal with oral flumazenil

Flumazenil is traditionally administered intravenously to reverse the adverse effects of over sedation with benzodiazepines. The aim of this study was to test postoperative cognitive and psychomotor recovery from midazolam conscious sedation, following reversal with orally administered flumazenil. It was hypothesised that when administered by the oral route, flumazenil may enhance recovery over a prolonged period, thus increasing safety. Eighteen patients requiring intravenous midazolam sedation for dental treatment completed a randomised, double-blind, crossover trial. Following treatment the patients' sedation was reversed using either flumazenil or saline (as placebo), administered orally, on alternate appointments. Assessment of mood and cognitive function were undertaken using ClinPhone.cdr(R), a highly sensitive and specific computerised battery of cognitive tests administered by telephone prior to sedation and every hour for seven hours post reversal. Results indicate that within 20 min of administration, oral flumazenil is capable of partially reversing some cognitive and psychomotor impairments but the attentional and stimulus discrimination effects of midazolam sedation still remain.

Seminars on controversial issues. A review of the pharmacological approach to the management of dental anxiety in children

This paper aims to review the existing literature on the pharmacology of a number of sedative drugs used in the management of dental anxiety in the conscious child patient. Pharmacological agents may be used as a complement to behavioural techniques to assist in the management of anxiety in some paediatric dental patients. Their use may also be especially indicated in children with disabilities. These agents are usually sedative in action and do not, in themselves, eliminate anxiety but merely enhance patient acceptance by reducing arousal and modifying anticipation of danger. The agents used are varied and diverse and include nitrous oxide, benzodiazepines and narcotics. Nitrous oxide has proved to be of particular value but carries a degree of risk for the operating staff. Amongst the benzodiazepines, Midazolam has been used more frequently in recent years. It may be given by a variety of routes, including intra-nasally. Dentists who employ sedative agents and techniques should be familiar with the pharmacology of the agents selected, be cognisant of the risks and benefits of the technique employed and be able to manage any adverse events that may arise through their use.

Referrals to a secondary care dental clinic for anxious adult patients: implications for treatment

OBJECTIVES

This study aimed to determine the methods suggested by general dental practitioners for management of patients with dental anxiety whom they refer to a dental hospital setting, the treatment modalities eventually used with such patients and the relationship between patients previous sedation experience and the current referral.

METHODS

Consecutive referral letters (n = 125) for management of patients with dental anxiety over a 16 month period were analysed for content, including reason for referral and suggested treatment modalities. Patient records were also examined for previous sedation experience.

RESULTS

From 115 referrals eligible for analysis, the dentists requested management of anxiety using pharmacological methods in 113 referrals with only two referrals mentioning psychologically-based treatments. In secondary care, 29% of the adult referrals opted for dental treatment using psychological techniques alone.

CONCLUSIONS

In spite of the efficacy of psychological treatments for dental anxiety, primary and secondary care dentists appear not to be suggesting or promoting their use for patients with dental anxiety. Further research into the availablility of, and barriers to accessing the full range of services for those with dental anxiety, including patient perspectives, needs to be undertaken.

Dose-dependent effects of flumazenil on cognition, mood, and cardio-respiratory physiology in healthy volunteers

OBJECTIVES

To assess the possible effects of flumazenil on cognitive processing, physiology, and mood. Design A double-blind, placebo controlled, four-way cross-over study, using healthy volunteers.

METHODS

On each of 4 separate visits, 16 participants received 0.5 mg, 2.5 mg, 5.0 mg of flumazenil, or normal saline. They then performed a computerised test battery assessing cognitive function. Measures of pulse rate, arterial oxygen saturation and mean arterial pressure were also taken. Finally, participants completed visual analogue scales assessing their subjective mood state.

RESULTS

The majority of cognitive tasks showed dose-dependent declines in performance. Mean arterial pressure was significantly reduced, as was pulse rate. Subjective alertness showed a similar decline.

CONCLUSIONS

Flumazenil has been clinically described as an agent with few intrinsic properties, whose primary effect lies in its ability to reverse benzodiazepine-induced states. This study has shown that flumazenil does possess intrinsic activity which have a significant effect on cognition, cardiovascular physiology and mood. Clinicians need to be aware of these effects.