Risk factors for chloral hydrate sedation failure in pediatric patients: a retrospective analysis.

Background: This study aimed to investigate the risk factors for chloral hydrate sedation failure and complications in a tertiary children's hospital in South Korea. Methods: A retrospective analysis of pediatric procedural sedation with chloral hydrate between January 1, 2021, and March 30, 2022, was performed. The collected data included patient characteristics, sedation history, and procedure. Multivariable regression analysis was performed to identify the risk factors for procedural sedation failure and complications. Results: A total of 6691 procedural sedation were included in the analysis; sedation failure following chloral hydrate (50 mg/kg) occurred in 1457 patients (21.8%) and was associated with a higher rate of overall complications compared to those with successful sedation (17.5% [225 / 1457] vs. 6.2% [322 / 5234]; P < 0.001; odds ratio, 3.236). In the multivariable regression analysis, the following factors were associated with increased risk of sedation failure: general ward or intensive care unit inpatient (compared with outpatient); congenital syndrome; oxygen dependency; history of sedation failure or complications with chloral hydrate; procedure more than 60 min; and magnetic resonance imaging, radiotherapy, or procedures with painful or intense stimuli (all P values < 0.05). Factors contributing to the complications included general ward inpatient, congenital syndromes, congenital heart disease, preterm birth, oxygen dependency, history of complications with chloral hydrate, and current sedation failure with chloral hydrate (all P values < 0.05). Conclusions: To achieve successful sedation with chloral hydrate, the patient's sedation history, risk factors, and the type and duration of the procedure should be considered.

Comparison of intranasal dexmedetomidine alone and dexmedetomidine-chloral hydrate combination sedation for electroencephalography in children: A large retrospective cohort study and propensity score-matched analysis.

Aim: To compare the safety and efficacy of intranasal high-dose dexmedetomidine (DEX) versus a combination of intranasal low-dose dexmedetomidine and oral chloral hydrate (DEX-CH) sedation during electroencephalography (EEG) in children. Methods: Unadjusted analysis, 1:1 propensity score matching (PSM), and inverse probability of treatment weighting (IPTW) were used to compare the sedation success rate, adverse effects, onset time, and recovery time of these two sedation methods for 6967 children who underwent EEG. Results: A total of 6967 children were enrolled in this study, of whom 846 (12.1 %) underwent DEX intranasal sedation while 6121 (87.9 %) received DEX-CH sedation. No significant differences were observed in the sedation success rate with the first dose between the two groups [824 (97.4 %) for DEX vs. 5971 (97.6 %) for DEX-CH; RR 0.99; 95 % CI, 0.98-1.01; P = 0.79]. Similarly, there were no notable disparities in the incidence of adverse events [16 (1.9 %) for DEX vs. 101 (1.7 %) for DEX-CH; RR 1.15; 95 % CI, 0.68-1.93; P = 0.32]. However, intranasal DEX sedation compared with DEX-CH sedation was associated with lower vomiting [0 vs. 95(1.6 %); RR 0.04; 95 % CI, 0.02-0.6; P = 0.02] or more bradycardia [13(1.5 %) vs. 2(0.03 %); RR 47.03; 95 % CI, 10.63-208.04; P < 0.001]. Multivariate analysis using PSM and IPTW analysis yielded similar results. Conclusion: Both methods for EEG had high sedation success rate and low incidence of adverse events. High-dose intranasal DEX was more likely to induce bradycardia and had a shorter recovery time than the DEX-CH sedation, which was more likely to induce vomiting.

Short-term chloral hydrate as an add-on treatment may improve sleep and alleviate agitation in inpatients with treatment resistant schizophrenia: a retrospective case series study.

Introduction: Chloral hydrate (CH), a medication dating back to 1832, is tranquilizer and sleep promoter still used today. It remains an option for short-term insomnia therapy and sedation before medical procedures, despite its controversial safety profile. Methods: This study investigated the potential benefits of chloral hydrate addition for increasing sleep duration and reducing agitation and violence in inpatients with treatment-resistant schizophrenia (TRS). A retrospective, observational case series design was utilized, analyzing data from fourteen patients diagnosed with TRS disorders. Results: CH addition increased the rate of full night sleep and decreased the rates of agitation and verbal and physical violence events. Notably, no adverse events including falls were reported during CH addition. Discussion: CH shows some short-term benefits in improving sleep disorders and reducing violent and agitated behavior in patients with TRS. Our study has limitations due to its small sample size, retrospective design and lack of a control group. A large-scale, double-blind, randomized trial is needed to further explore the efficacy and safety of CH in psychiatric populations with TRS accompanied by agitation, violence and disturbed sleep.

Efficacy and safety of chloral hydrate in auditory brainstem response test: A systematic review and single-arm meta-analysis.

OBJECTIVES: To evaluate the safety and efficacy of chloral hydrate in auditory brainstem response (ABR) tests. SETTING AND DESIGN: In this study, the authors systematically searched both English (Embase, PubMed, and Web of Science) and Chinese (Chinese National Knowledge Infrastructure, Wanfang Data, and VIP Chinese Science) databases. Two authors independently performed data extraction and quality assessment. The pooled sedation failure rate and the pooled incidence of adverse events were calculated via a random-effects model. Sensitivity and subgroup analyses were performed to explore the sources of heterogeneity, and the PRISMA guideline was followed. PARTICIPANTS: Patients with ABR tests receiving chloral hydrate sedation. MAIN OUTCOME MEASURES: The pooled sedation failure rate and the pooled incidence of adverse events. RESULTS: A total of 23 clinical studies were included in the final analysis. The pooled sedation failure rate of patients who received chloral hydrate sedation before ABR examination was 10.0% [95% confidence interval (CI) (6.7%, 15.0%), I2 = 95%, p < .01]. There were significant differences in the prevalence of sedation failure between sample sizes greater than 200 and those less than or equal to 200 (5.6% vs. 19.6%, p < .01) and between the studies that reported sleep deprivation and those that did not report sleep deprivation (7.1% vs. 18.9%, p < .01). The pooled incidence of adverse events was 10.32% [95% CI (5.83%, 14.82%), I2 = 98.1%, p < .01]. CONCLUSIONS: Chloral hydrate has a high rate of sedation failure, adverse events, and potential carcinogenicity. Therefore, replacing its use in ABR tests with safer and more effective sedatives is warranted.

Melatonin versus chloral hydrate on sleep induction for recording electroencephalography in children: a randomized clinical trial.

Background: Electroencephalography (EEG) plays an essential role in the diagnosis of seizures. EEG recording in children is done with partial sleep deprivation and sedative drugs. To compare the effectiveness of melatonin and chloral hydrate on sleep induction and EEG recording in children. Materials and methods: In a parallel blinded randomized clinical trial study, 78 patients (6 months-5 years) were included to record EEG. Patients were randomly divided into two groups to receive melatonin (0.4 mg/kg) or chloral hydrate (0.5 ml/kg). After receiving the sedative drug, the start and duration of sedation, recovery time, side effects, and epileptiform waves in the EEG were recorded. The data was analyzed using SPSS version 16, and the significance level was determined to be less than 0.05. Results: A total of 78 children, including 34 girls (43.6%) and 44 boys (56.4%) (average age of 27.15±17.15 months), were examined. Success in the induction of sedation was reported by melatonin in 36 patients (92%) and chloral hydrate in 37 patients (95%), which was similar between the two drugs (P=0.5). The start time (P=0.134) and the duration of sedation (P=0.408) were alike between the two drugs. However, compared to the chloral hydrate, the recovery time in the melatonin group was significantly shorter (P<0.001). Side effects were not seen in melatonin, while six children (15%) using chloral hydrate had mild side effects (P=0.013). Epileptiform waves in EEGs were reported to be similar and positive for melatonin in 18 children (50%) and chloral hydrate in 16 children (43%) (P=0.410). Conclusion: The findings show that using melatonin in the dose prescribed in this study had similar effects to success in inducing sedation with the minimum quantity of chloral hydrate. Regardless of the start time and duration of sedation, the shorter recovery time and the absence of side effects are the advantages of using melatonin.

Effects of Dextrose Supplementation on Chloral Hydrate Sedation: A Double-Blinded, Randomized, Prospective Study.

Sedation plays a crucial role in successful pediatric imaging, and chloral hydrate is commonly used for this purpose. However, the challenges associated with chloral hydrate administration, such as its unpleasant taste and potential induction of vomiting, remain a concern. Sweet oral solutions have emerged as potential solutions for reducing distress and providing analgesia. This study compared the efficacy of dextrose combined with chloral hydrate with that of conventional sedation methods. This prospective, double-blind, randomized controlled clinical study enrolled 160 pediatric outpatients scheduled for echocardiography. Chloral hydrate syrup (100 mg/mL) was supplemented with a dextrose solution (dextrose group) or distilled water (control group) in a 1:10 volume ratio. The sedation achievement time, Skeie scale score, revised Face, Legs, Activity, Cry, and Consolability (FLACC) score, and side effects (nausea, vomiting, hypoxia, and respiratory depression) were assessed. No significant difference in average time to achieve sedation was observed between the dextrose and control groups (24.4±17.8 vs. 24.7±17.1 min, p=0.92). Both groups demonstrated similar levels of sedation according to the Skeie scale and mean revised FLACC score. Although the occurrence rates of nausea and vomiting had no significant differences, the dextrose group had no cases of vomiting in children aged >24 months compared to the control group, which had three cases (30%). In conclusion, the addition of dextrose to chloral hydrate did not significantly affect sedation time, anxiety, pain reduction, or occurrence of gastrointestinal complications during sedation.

Comparative Study of the Effect of Oral Chloral Hydrate and Intranasal Fentanyl on Sedation in Children for Electroencephalography.

Objectives: Sedation and stability during electroencephalography (EEG) in pediatrics have high clinical importance. This study compares the sedative properties of oral chloral hydrate (OCH) and intranasal fentanyl (INF). Materials & Methods: This study was a randomized clinical trial conducted in 2020 in Isfahan City on sixty-two pediatric candidates for EEG. Patients were randomized into two groups receiving 50 mg/kg OCH and 2 µg/kg INF thirty minutes before the process. The heart rate (HR), mean arterial pressure (MAP), respiratory rate (RR), and oxygen saturation (O2 sat) of patients, sedation, and physician's satisfaction were measured and compared between groups. Results: The HR of patients decreased significantly in both groups (P< 0.001), and the patients that received INF had significantly lower HR 15, 30, 45, and 60 minutes after drug administrations (P< 0.05). RR evaluation indicated significantly decreased RR in both groups (P< 0.001), and patients receiving INF had lower RR 30, 45, and 60 per minutes after drug administrations (P< 0.001). Both groups showed significantly increased sedation levels during the study (P< 0.001), and patients treated with INF had higher sedation levels 15, 30, and 45 minutes after drug administration. Satisfaction rates were higher among the group that received INF (P= 0.020). Conclusion: The use of INF had significant analgesic and sedative effects on pediatrics undergoing EEG.

Efficacy of Melatonin for Inducing Sleep in Pediatric Electroencephalogram Recordings: A Single-Blind Randomized Controlled Pilot Study.

Objective To compare the efficacy of melatonin, melatonin with sleep deprivation, and chloral hydrate with sleep deprivation on sleep induction in Asian children. Methods: For this randomized single-blind controlled trial, we recruited 45 children aged 1-5 years and older who were not cooperative on electroencephalogram (EEG) recordings, randomly allocated to three groups: melatonin (group A), melatonin and sleep deprivation (group B), or chloral hydrate and sleep deprivation (group C). Between-group comparisons were performed using the Kruskal-Wallis and Mann-Whitney U tests. Results: Stage II sleep was achieved in 92.8%, 100%, and 100% of participants in groups A, B, and C, respectively. Sleep latency was significantly shorter in Group C than in Groups A (p = .022) and B (p = .027), while Group C had better sleep efficacy than Groups A (p = .02) and B (p = .04). Conclusion: Melatonin with sleep deprivation is less effective at inducing sleep than combined chloralhydrate and sleep deprivation.

Genetic and Phenotypic Analyses of Carpel Development in Arabidopsis.

Carpels are the female reproductive organs of the flower, organized in a gynoecium, which is likely the most complex organ of the plant. The gynoecium provides protection for the ovules, helps to discriminate between male gametophytes, and facilitates successful pollination. After fertilization, it develops into a fruit, a specialized organ for seed protection and dispersal. To carry out all these functions, coordinated patterning and tissue specification within the developing gynoecium has to be achieved. In this chapter, we provide different methods to characterize defects in carpel morphogenesis and patterning associated with developmental mutations, as well as a list of reporter lines that can be used to facilitate genetic analyses.

Retrospective observational study of chloral hydrate use in mechanically-ventilated pediatric intensive care unit (PICU) patients 2012-2017.

Introduction: Chloral hydrate (CH) has long been utilized as a pediatric procedural sedation agent. However, very little is published describing CH use in a pediatric intensive care unit (PICU) setting. The aim of this retrospective observational cohort study was to investigate and describe the use of CH in mechanically-ventilated, critically ill children at a large pediatric tertiary referral hospital. Methods: Data were extracted from the hospital electronic medical record and a locally maintained registry of all children admitted to the PICU between 2012 and 2017. Patients admitted to the cardiovascular ICU were not included in this review. The clinical and pharmacy data for 3806 consecutive PICU admissions of mechanically-ventilated, critically ill children were examined. Results: 283 admissions received CH during their first ICU stay. CH-exposed children were younger (16 months vs. 35 months, p < 0.001), the median total dose of CH (indexed to duration of ventilation) was 11 mg/kg/day, the median time to first CH dose was 3 days and more CH doses were administered at night (1112 vs. 958, p < 0.001). We constructed a propensity score to adjust for the differences in patients with and without CH exposure using logistic regression including variables of age, sex, diagnosis, and PRISM3 score. After adjustment, the median length of mechanical ventilation was 5 days longer in the CH-exposed group (95% Confidence Interval [CI] 4-6) compared to unexposed CH patients. Similarly, the median length of ICU duration was 9.4 days longer (95% CI 7.1-11.6) and median length of hospital admission duration was 13.2 days longer (95% CI 7.8-18.6) in CH-exposed patients compared to CH-non-exposed. After adjustment, CH-exposed patients had a 9% higher median exposure to HFOV (95% CI 3.9-14.6), but did not have higher median exposures to new tracheostomy (95% CI -0.4-2.2) or ECMO (95% CI -0.2-5.0). Discussion: As part of an extended sedation regimen in mechanically-ventilated and critically ill children, CH is associated with somewhat higher complexity of illness and longer ICU durations.

Trichloroethanol, an active metabolite of chloral hydrate, modulates tetrodotoxin-resistant Na+ channels in rat nociceptive neurons.

BACKGROUND: Chloral hydrate is a sedative-hypnotic drug widely used for relieving fear and anxiety in pediatric patients. However, mechanisms underlying the chloral hydrate-mediated analgesic action remain unexplored. Therefore, we investigated the effect of 2',2',2'-trichloroethanol (TCE), the active metabolite of chloral hydrate, on tetrodotoxin-resistant (TTX-R) Na+ channels expressed in nociceptive sensory neurons. METHODS: The TTX-R Na+ current (INa) was recorded from acutely isolated rat trigeminal ganglion neurons using the whole-cell patch-clamp technique. RESULTS: Trichloroethanol decreased the peak amplitude of transient TTX-R INa in a concentration-dependent manner and potently inhibited persistent components of transient TTX-R INa and slow voltage-ramp-induced INa at clinically relevant concentrations. Trichloroethanol exerted multiple effects on various properties of TTX-R Na+ channels; it (1) induced a hyperpolarizing shift on the steady-state fast inactivation relationship, (2) increased use-dependent inhibition, (3) accelerated the onset of inactivation, and (4) retarded the recovery of inactivated TTX-R Na+ channels. Under current-clamp conditions, TCE increased the threshold for the generation of action potentials, as well as decreased the number of action potentials elicited by depolarizing current stimuli. CONCLUSIONS: Our findings suggest that chloral hydrate, through its active metabolite TCE, inhibits TTX-R INa and modulates various properties of these channels, resulting in the decreased excitability of nociceptive neurons. These pharmacological characteristics provide novel insights into the analgesic efficacy exerted by chloral hydrate.

Nrf2 regulates the activation of THP-1 cells induced by chloral hydrate.

Trichloroethylene (TCE) triggers a severe hypersensitivity syndrome in the occupational population dependent on dendritic cells (DCs). Chloral hydrate (CH), the major oxidative metabolite of TCE, has been proved to be the culprit causative substance of TCE-induced hypersensitivity by human patch tests. Because redox imbalance is essential for chemical sensitizers-induced maturation of DCs, we predicted that CH would activate DCs by the nuclear factor E2-related factor 2 (Nrf2)-mediated antioxidant response. This study selected THP-1 cells as the in vitro DC model, and we evaluated the cell activation markers, intracellular oxidative stress, and Nrf2 pathway related genes expression in response to CH in THP-1 cells. CH displayed significant stimulation of THP-1 cells activation, including CD54 and CD86 expression, IL-8 release, and cell migration, and damaged the redox balance by triggering ROS generation, GSH consumption, and antioxidase activities modulation. The levels of Nrf2 and its downstream genes (HO-1 and NQO1) in mRNA and protein expressions were upregulated by CH, and CH also promoted the nuclear translocation of Nrf2. Subsequently, we investigated the effects of antioxidant on Nrf2-mediated cell defense in CH treated cells. Pretreatment with curcumin dramatically reduced cell activation and oxidative stress triggered by CH in THP-1 cells. We also confirmed the specific role of Nrf2 in CH-induced cell activation using NRF2-knockout cells. Deficiency of Nrf2 inhibited cell activation and downregulated HO-1 and NQO1 expression in CH-challenged cells. These findings suggest that Nrf2-dependent redox homeostasis plays a pivotal role in CH-induced activation of THP-1 cells, thereby providing new knowledge of the allergen as well as the molecular mechanism involving in TCE-induce hypersensitivity syndrome.

A Survey on Procedural Sedation and Analgesia for Pediatric Facial Laceration Repair in Korea.

Background Most children with facial lacerations require sedation for primary sutures. However, sedation guidelines for invasive treatment are lacking. This study evaluated the current status of the sedation methods used for pediatric facial laceration repair in Korea. Methods We surveyed one resident in each included plastic surgery training hospital using face-to-face interviews or e-mail correspondence. The health care center types (secondary or tertiary hospitals), sedation drug types, usage, and dosage, procedure sequence, monitoring methods, drug effects, adverse events, and operator and guardian satisfaction were investigated. Results We included 45/67 hospitals (67%) that used a single drug, ketamine in 31 hospitals and chloral hydrate in 14 hospitals. All health care center used similar sedatives. The most used drug administered was 5 mg/kg intramuscular ketamine (10 hospitals; 32%). The most common chloral hydrate administration approach was oral 50 mg/kg (seven hospitals; 50%). Twenty-two hospitals (71%) using ketamine followed this sequence: administration of sedatives, local anesthesia, primary repair, and imaging work-up. The most common sequence used for chloral hydrate (eight hospitals; 57%) was local anesthesia, administration of sedatives, imaging work-up, and primary repair. All hospitals that used ketamine and seven (50%) of those using chloral hydrate monitored oxygen saturation. Median operator satisfaction differed significantly between ketamine and chloral hydrate (4.0 [interquartile range, 4.0-4.0] vs. 3.0 [interquartile range, 3.0-4.0]; p <0.001). Conclusion The hospitals used various procedural sedation methods for children with facial lacerations. Guidelines that consider the patient's condition and drug characteristics are needed for safe and effective sedation.

Daytime Variation of Chloral Hydrate-Associated Sedation Outcomes: A Propensity-Matched Cohort Study.

BACKGROUND: Physiological processes influencing a drugs' efficacy change substantially over the course of the day. However, it is unclear whether there is an association between the sedative success rate of chloral hydrate and the time of day. We conducted a retrospective study of 41,831 cases, to determine if there was a difference in sedation success rate with chloral hydrate in children seen in the morning and afternoon. METHODS: Patients who accepted the sedation service were included. Eligible patients were divided into two cohorts of morning and afternoon cases, according to the time of day when the initial dose of chloral hydrate was administered. To ensure that the two groups were comparable, a propensity score matching method was utilized. RESULTS: The success rate with the initial dose of chloral hydrate was higher in patients who received sedation services in the afternoon. In the subgroup analysis, the afternoon cases had a higher sedation success rate compared to the morning cases in male patients; whereas, in female patients, no difference was detected between the morning versus afternoon cases. CONCLUSIONS: These results show that the afternoon cases had a higher sedation success rate than the morning cases, despite the afternoon cases receiving relatively lower initial dose than the morning cases. However, the clinical significance remains to be discussed, and further prospective studies are needed to validate the findings.

Correlation between the actual sleep time 24 hours prior to an examination and the time to achieve chloral hydrate sedation in pediatric patients in South Korea: a prospective cohort study.

PURPOSE: This study investigated correlations between the actual sleep time 24 hours prior to an examination and the time to achieve chloral hydrate sedation in pediatric patients. METHODS: With parental consent, 84 children who were placed under moderate or deep sedation with chloral hydrate for examinations from November 19, 2020 to July 9, 2022 were recruited. RESULTS: Patients' average age was 19.9 months. Pediatric neurology patients and those who underwent electroencephalography took significantly longer to achieve sedation with chloral hydrate. There was a negative correlation between the time to achieve sedation and actual sleep time within 24 hours prior to the examination. Positive correlations were found between the actual sleep time 24 hours prior to the examination and the second dose per weight, as well as between the sedation recovery time and awake hours before the examination. CONCLUSION: Sleep restriction is not an effective adjuvant therapy for chloral hydrate sedation in children, and sedation effects vary according to pediatric patients' characteristics. Therefore, it would be possible to reduce the unnecessary efforts of caregivers who restrict children's sleep for examinations. It is more important to educate parents about safe sedation than about sleep restriction.

Comparison of oral triclofos and intranasal midazolam and dexmedetomidine for sedation in children undergoing magnetic resonance imaging (MRI): an open-label, three-arm, randomized trial.

The purpose of this study was to compare the efficacy of oral triclofos (TRI), intranasal midazolam (INM), and intranasal dexmedetomidine (IND) in achieving successful sedation in children undergoing MRI. This open-label, three-arm, randomized trial was conducted in a tertiary care teaching hospital over 18-month period. Children scheduled for MRI were enrolled. Rate of successful/adequate sedation was assessed using the Paediatric Sedation State Scale (PSSS). The primary outcome was the efficacy (successful sedation or sedation rate) of the three drugs. One-hundred and ninety-five children were included for the MRI procedure. IND was found to be superior in terms of achieving successful sedation. INM had a shorter onset and duration of sedation compared to IND and TRI, but with an increased failure rate (88.3%). Keeping INM as the reference group, it was found that the odds of sedation increased 4.1 times on changing from INM to IND (p < 0.01), and 2.26 times on changing from INM to TRI (p < 0.01). Adverse events included nasal discomfort (18.3%) in INM group; and self-limited tachycardia (4.6%) and hypotension (10.8%) in the IND group. CONCLUSION: IND was more efficacious than INM or TRI for procedural sedation in children undergoing MRI without any significant adverse events. CLINICAL TRIAL REGISTRATION: CTRI/2019/01/017257; date registered: 25/01/2019. WHAT IS KNOWN: • Oral triclofos (TRI) and intranasal midazolam (INM) have been used for procedural sedation in children undergoing MRI with variable success; but the experience with intranasal dexmedetomidine (IND) is limited. WHAT IS NEW: • IND provides more effective sedation compared to INM or TRI for procedural sedation in children undergoing MRI, without any significant adverse events.

Two-center randomized controlled trial comparing oral chloral hydrate and intranasal combination of dexmedetomidine and ketamine for procedural sedation in children: study protocol.

BACKGROUND: Oral chloral hydrate is widely used in pediatric sedation. Intranasal dexmedetomidine has been increasingly used for pediatric sedation; however, its improvement is warranted. The combination of dexmedetomidine with ketamine can improve onset and hemodynamic stability while maintaining sedative efficacy. This study aims to determine the efficacy and safety of intranasal combination of dexmedetomidine and ketamine compared to oral chloral hydrate. METHODS: This is a prospective, parallel-arm, single-blinded, two-center, superiority randomized controlled trial with 1:1 allocation, designed to compare the effects of intranasal combination of dexmedetomidine and ketamine with those of oral chloral hydrate. We shall enroll 136 patients aged < 7 years old in this study. Prior to the procedure, we shall randomize each patient into the control group (oral chloral hydrate 50 mg/kg) or study group (intranasal dexmedetomidine 2 µg/kg and ketamine 3 mg/kg). The primary outcome will be the rate of achieving an adequate sedation level (6-point Pediatric Sedation State Scale 1, 2, or 3) within 15 min. In addition, we shall measure the sedation time, sedation failure rate, completion of procedure, adverse events, patient acceptance, and physician satisfaction. DISCUSSION: This study will provide evidence of the efficacy and safety of the intranasal combination of dexmedetomidine and ketamine in comparison with oral chloral hydrate. TRIAL REGISTRATION: ClinicalTrials.gov , NCT04820205. Registered on 19th March 2021.

Identification of the Acid-Sensitive Site Critical for Chloral Hydrate (CH) Activation of the Proton-Activated Chloride Channel.

The transmembrane protein TMEM206 was recently identified as the molecular basis of the extracellular proton-activated Cl- channel (PAC), which plays an essential role in neuronal death in ischemia-reperfusion. The PAC channel is activated by extracellular acid, but the proton-sensitive mechanism remains unclear, although different acid-sensitive pockets have been suggested based on the cryo-EM structure of the human PAC (hPAC) channel. In the present study, we firstly identified two acidic amino acid residues that removed the pH-dependent activation of the hPAC channel by neutralization all the conservative negative charged residues located in the extracellular domain of the hPAC channel and some positively charged residues at the hotspot combined with two-electrode voltage-clamp (TEVC) recording in the Xenopus oocytes system. Double-mutant cycle analysis and double cysteine mutant of these two residues proved that these two residues cooperatively form a proton-sensitive site. In addition, we found that chloral hydrate activates the hPAC channel depending on the normal pH sensitivity of the hPAC channel. Furthermore, the PAC channel knock-out (KO) male mice (C57BL/6J) resist chloral hydrate-induced sedation and hypnosis. Our study provides a molecular basis for understanding the proton-dependent activation mechanism of the hPAC channel and a novel drug target of chloral hydrate.SIGNIFICANCE STATEMENT Proton-activated Cl- channel (PAC) channels are widely distributed in the nervous system and play a vital pathophysiological role in ischemia and endosomal acidification. The main discovery of this paper is that we identified the proton activation mechanism of the human proton-activated chloride channel (hPAC). Intriguingly, we also found that anesthetic chloral hydrate can activate the hPAC channel in a pH-dependent manner. We found that the chloral hydrate activates the hPAC channel and needs the integrity of the pH-sensitive site. In addition, the PAC channel knock-out (KO) mice are resistant to chloral hydrate-induced anesthesia. The study on PAC channels' pH activation mechanism enables us to better understand PAC's biophysical mechanism and provides a novel target of chloral hydrate.

Screening of new adsorbents to remove algal organic matter from aqueous solutions: kinetic analyses and reduction of disinfection by-products formation.

The algal organic matter (AOM) is a problem in water treatment. Although the adsorption process is extensively applied to drinking water treatment, little information is known about the potential of new adsorbents to remove AOM. Herein, this work evaluated the removal of AOM and its main compounds (dissolved organic carbon (DOC), carbohydrate, and protein) by new adsorbents-mesoporous silica (SBA-16), graphene oxide material from citric acid (CA), and sugar (SU), and a composite of CA immobilized on sand (GSC). In general, the removal efficiencies followed the order of SBA-16 > CA > SU or GSC for DOC, carbohydrate, and protein. At environmental condition (5 mg DOC·L-1 and pH 8), high removals were reported for SBA-16 (88.8% DOC, 80.0% carbohydrate, and 99.6% protein) and CA (70.0% DOC, 66.7% carbohydrate, and 89.7% protein), while moderate removals were found for SU (60.5% DOC, 47.9% carbohydrate, and 66.5% protein) and GSC (67.4% DOC, 60.8% carbohydrate, and 57.4% protein). Based on these results, further analyses were done with SBA-16 and CA. Both adsorbents' efficiencies decayed with the pH increment of the test water. Disinfection by-products reductions found using SBA-16 - trihalomethanes (58.2 to 94.7%) and chloral hydrate (48.7 to 78.8%) - were higher than the ones using CA-trihalomethanes (45.2 to 82.4%) and chloral hydrate (40.1 to 70.8%). This study showed the potential of applying these adsorbents for AOM removal, and further investigations are suggested to increase the adsorption capacity of these adsorbents.