Optoelectronic and photocatalytic behaviour of a type-II GaAlS2/HfS2heterostructure:ab initiostudy.

Theoretical examination based on first principle computation has been conducted for van der Waals heterostructure (vdwHS) GaAlS2/HfS2including structural, optoelectronic and photocatalytic characteristics. From the adhesion energy calculation, the AB configuration of GaAlS2/HfS2vdwHS is the most stable. A type-II GaAlS2/HfS2vdwHS is a dynamically and thermally stable structure. The band edge position, projected band, and projected charge densities verify the type-II alignment of GaAlS2/HfS2vdwHS. For GaAlS2/HfS2, GaAlS2is acting as a donor and HfS2is acting as an acceptor ensured by the charge density difference plot. The electron localized function validates the weak van der Waals interaction between GaAlS2and HfS2. The GaAlS2/HfS2vdwHS possess an indirect bandgap of 1.54 eV with notable absorption in the visible range. The findings assure that the GaAlS2/HfS2vdwHS is an efficient photocatalyst for pH 4-8. The band alignment of GaAlS2/HfS2is suitable for Z-scheme charge transfer. The strain influenced band edge suggests that the GaAlS2/HfS2vdwHS remains photocatalytic for strain-4%to+6%in both cases of uniaxial and biaxial strains.

Evaluation of the Efficacy of a Neem Extract-Based Herbal Ointment, Herbal Antioxidant, and Propolis on Oxidative Stress Related to Oral Ulcers: An Interventional Animal Study.

Traumatic oral ulcers are one of the most commonly encountered oral ulcers. Their healing may be delayed due to factors like the presence of opportunistic infectious microbes in the oral cavity, secondary trauma from sharp edges of teeth, and the systemic condition of the patient. AIM: To compare the efficacy of a newly developed neem extract containing herbal ointments (propolis and Hemidesmus indicus) in enhancing the wound contraction of traumatic oral ulcers and to determine the relationship between oxidative stress and oral ulcers. METHOD: Ulcers were inflicted by trauma in the mouths of experimental rabbits using a 5 mm punch biopsy device. Forty-eight animals were randomly put into six groups (n = 12). Group 1 was the control group that did not receive any intervention; Group 2 had a systemic treatment of Hemidesmus indicus extract; Group 3 received a topical application of propolis; Group 4 had a topical application of a neem extract-based herbal ointment; Group 5 was administered a combination of Hemidesmus indicus and propolis; and Group 6 had a combination of a neem-based herbal ointment and Hemidesmus indicus. Oxidative stress levels were calculated by measuring superoxide dismutases and malondialdehyde levels in the blood on days 0, one, seven, and 14. Wound contraction scores of ulcers were also assessed on days seven and 14. RESULTS: Significantly higher wound contraction scores were seen in groups treated with herbal ointment in comparison to groups treated without herbal ointment. Oxidative stress levels increased in all groups after the infliction of ulcers (day one) and then declined as the ulcers healed, reaching near-normal levels on day 14. Groups containing Hemidesmus indicus showed a significant reduction in oxidative stress in comparison to groups without Hemidesmus indicus. A p-value of <0.05 was considered significant. CONCLUSION: A combined formulation of herbal ointment and Hemidesmus indicus proved to be the most efficacious in enhancing wound contraction of oral ulcers along with significantly reducing oxidative stress in experimental rabbits.

Cyanobacteria and microalgae growing on monuments of UNESCO World Heritage site Champaner Pavagadh, India: biofilms and their exopolysaccharide composition.

The present study investigated the biofilm organisms growing on selected monuments of the Champaner Pavagadh complex (Gujarat, India), which is a UNESCO World Heritage Site. The cyanobacteria and microalgae were isolated from biofilms collected through non-destructive methods. The identification of these biological organisms was done using micro-morphological characters and confirmed by 16S rRNA gene sequencing. The exopolysaccharide of each of the isolated strains was extracted, hydrolysed and analysed by the HPTLC. Six isolated strains representing five cyanobacteria and one microalga belong to the genera Desmonostoc, Nostoc, Leptolyngbya, Chroococcidiopsis and Asterarcys. The relationships between substrates' specificity of these isolated biofilm organisms and those identified globally were evaluated using maximum parsimony analysis to generate a consensus phylogenetic tree. The five strains of cyanobacteria isolated were closely clustered with cyanobacteria belonging to a tropical region. At the generic level, no relationship between the species and substratum specificity was recorded. The exopolysaccharide analysis of the isolated strains revealed the presence of seven monosaccharides. While glucose was present in all the analysed species, the concentration of either fucose or arabinose was high. The current study presents a novel HPTLC-based method for determination of monosaccharides composition from the extracellular polymeric substances.

A majority of uninfected adults show preexisting antibody reactivity against SARS-CoV-2.

Preexisting cross-reactivity to SARS-CoV-2 occurs in the absence of prior viral exposure. However, this has been difficult to quantify at the population level due to a lack of reliably defined seroreactivity thresholds. Using an orthogonal antibody testing approach, we estimated that about 0.6% of nontriaged adults from the greater Vancouver, Canada, area between May 17 and June 19, 2020, showed clear evidence of a prior SARS-CoV-2 infection, after adjusting for false-positive and false-negative test results. Using a highly sensitive multiplex assay and positive/negative thresholds established in infants in whom maternal antibodies have waned, we determined that more than 90% of uninfected adults showed antibody reactivity against the spike protein, receptor-binding domain (RBD), N-terminal domain (NTD), or the nucleocapsid (N) protein from SARS-CoV-2. This seroreactivity was evenly distributed across age and sex, correlated with circulating coronaviruses' reactivity, and was partially outcompeted by soluble circulating coronaviruses' spike. Using a custom SARS-CoV-2 peptide mapping array, we found that this antibody reactivity broadly mapped to spike and to conserved nonstructural viral proteins. We conclude that most adults display preexisting antibody cross-reactivity against SARS-CoV-2, which further supports investigation of how this may impact the clinical severity of COVID-19 or SARS-CoV-2 vaccine responses.

Antibody reactivity to SARS-CoV-2 is common in unexposed adults and infants under 6 months.

BACKGROUND: Pre-existing antibody reactivity against SARS-CoV-2 in unexposed people is a potentially important consideration for COVID-19 severity and vaccine responses. However, it has been difficult to quantify due to a lack of reliable defined background titers in unexposed individuals. METHODS: We measured IgG against multiple SARS-CoV-2 antigens, SARS-CoV and other circulating coronavirus spike proteins using a highly sensitive multiplex assay, and total SARS-CoV-2 spike-specific antibodies (IgG/M/A) using a commercial CLIA assay in 276 adults from the Vancouver area, Canada between May 17th and June 19th 2020. Reactivity threshold in unexposed individuals were defined comparing to pre-pandemic sera and to sera from infants under 6 months of age. RESULTS: The seroprevalence from a SARS-CoV-2 exposure, adjusted for false-positive and false-negative test results, was 0.60% in our adult cohort. High antibody reactivity to circulating endemic coronaviruses was observed in all adults and was about 10-fold lower in infants under 6 months. Consistent with a waning of maternal antibodies, reactivity in infants decreased more than 50-fold eight months later. SARS-CoV-2 Spike, RBD, NTD or nucleocapsid antibody reactivity >100-fold above that of older infants was detected in the vast majority of unexposed adults and pre-pandemic sera. This antibody reactivity correlated with titers against circulating coronaviruses, but not with age, sex, or whether adults were healthcare workers. CONCLUSION: A majority of unexposed adults have pre-existing antibody reactivity against SARS-CoV-2. The lack of similar antibody reactivity in infants where maternal antibodies have waned suggests that this cross-reactivity is acquired, likely from repeated exposures to circulating coronaviruses.

Continuation of Buprenorphine to Facilitate Postoperative Pain Management for Patients on Buprenorphine Opioid Agonist Therapy.

BACKGROUND: Acute pain management in patients on buprenorphine opioid agonist therapy (BOAT) can be challenging. It is unclear whether BOAT should be continued or interrupted for optimization of postoperative pain control. OBJECTIVES: To determine an evidence-based approach for pain management in patients on BOAT in the perioperative setting, particularly whether BOAT should be continued or interrupted with or without bridging to another mu opioid agonist and to identify benefits and harms of either perioperative strategy. STUDY DESIGN: Systematic literature review with qualitative data synthesis. SETTING: Hospital, perioperative. METHODS: The study protocol was registered on PROSPERO (Registration number 9030276355). Medline via OVID, EMBASE, CINAHL, and the Cochrane CENTRAL register of trials were searched for prospective or retrospective observational or controlled studies, case series, and case reports that described perioperative or acute pain care for patients on BOAT. References of narrative and systematic reviews addressing acute pain management in patients on BOAT and references of included articles were hand-searched to identify additional original articles for inclusion. The full text of publications were reviewed for final inclusion, and data were extracted using a standardized data extraction form. Results were summarized qualitatively. Primary outcomes were postoperative pain intensity and total opioid use and identification of benefits and harms of perioperative strategies. RESULTS: Eighteen publications presenting data on the perioperative management of patients on BOAT were identified: 10 case reports, 5 case series, and 3 retrospective cohort studies. Eleven articles reported continuation of BOAT, 2 concerned bridging BOAT, and 4 articles described stopping BOAT without planned bridging. In one retrospective cohort study, BOAT was continued in half and interrupted in half of patients. Patients on BOAT may have pain that is more difficult to treat than those who are not on OAT. There is no clear evidence that one particular strategy provides superior postoperative pain control, but interruption of BOAT may result in harm, including failure to return to baseline BOAT doses, continuing non-BOAT opioid use, or relapse of opioid use disorder. LIMITATIONS: There were a limited number of articles relevant to the study question consisting of case reports and retrospective observational studies. Some omitted relevant details. No prospective studies were found. CONCLUSIONS: There is no clear benefit to bridging or stopping BOAT but failure to restart it may pose concerns for relapse. We recommend continuing BOAT in the perioperative period when possible and incorporating an interdisciplinary approach with multimodal analgesia. KEY WORDS: Opioid use disorder, opiate substitution treatment, buprenorphine, buprenorphine-naloxone, buprenorphine opioid agonist therapy, postoperative pain, acute pain, multimodal analgesia.

Spectrophotometric analysis of the color stability of white mineral trioxide aggregate in contact with four different irrigating solutions - An in vitro study.

AIMS: This study aims to compare the color stability of white mineral trioxide aggregate (wMTA) in contact with four irrigating solutions. SETTINGS AND DESIGN: Original research study. SUBJECTS AND METHODS: Fifty cylindrical discs of wMTA, 10 mm in diameter and 2 mm in height were prepared using a mold. Samples were incubated at a temperature of 37°C and at 100% humidity for the material to reach its optimal mechanical properties. The samples were divided into 6 groups: Group A: dry (n = 5); Group B: distilled water (DW) (n = 5); Group C: 5% sodium hypochlorite (NaOCl) (n = 10); Group D: 2% chlorhexidine gluconate (CHX) (n = 10); Group E: 17% aqueous ethylene diamine tetra-acetic acid (EDTA) (n = 10); Group F: 0.2% Chitosan (n = 10) Each disc was immersed into the irrigating solution for a period of 24 h. All the specimens were photographed using a digital camera before and after immersion. The assessment of color change of each disc of wMTA was conducted by a spectrophotometer. The Commission Internationale de l'eclairage system was used to calculate the differences in color. STATISTICAL ANALYSIS USED: Statistical Package for the Social Sciences version 16.0 (Chicago, IL, USA) at a significance level of P < 0.05 was used. RESULTS: All groups except group A exhibited discoloration of wMTA. The mean values for change in color was highest with Group D, followed by Group C, F, E, B, and group A. Only Group B when compared to group A did not show any statistically significant difference (P = 0.948) whereas all the other four groups showed a highly statistically significant difference (P < 0.001). CONCLUSIONS: 2% CHX causes maximum discoloration of wMTA followed by 5% NaOCl, 0.2% Chitosan and least discoloration with 17% aqueous EDTA and DW.

Scanning electron microscopic evaluation of smear layer removal at the apical third of root canals using diode laser, endoActivator, and ultrasonics with chitosan: An in vitro study.

AIM: The aim of this study was to compare the effect of diode laser, endoActivator, and passive ultrasonics for smear layer removal at the apical third from root canals with 0.2% chitosan. MATERIALS AND METHODS: A total of 40 mandibular premolars were decoronated to establish a working length of 12 mm and shaped with ProTaper rotary files up to size F3. In Group A, canals were irrigated with 1 ml of 0.2% chitosan. In Group B, canals were initially irrigated with 0.8 ml of 0.2% chitosan and the remaining 0.2 ml was activated with diode laser. In Group C, canals were irrigated with 1 ml of 0.2% chitosan which was activated with endoActivator. In Group D, canals were irrigated with 0.2% chitosan and activated with passive ultrasonics. All samples were finally flushed with 3 ml of distilled water. The percentage of smear layer removal was analyzed with a scanning electron microscope examination at ×1000 and ×3000. Data were analyzed using Statistical Package for the Social Sciences version 16.0 (SPSS Inc., Chicago, IL, USA) at a significance level of P < 0.05. RESULTS: The mean value for Group B when compared to Group C for the removal of smear layer was higher, but there was no statistically significant difference between the two groups (P < 0.068 and P < 0.295). Both Group B and Group C showed a statistically significant difference (P < 0.001) when compared to Group A and Group D for the removal of smear layer. CONCLUSION: Diode laser and endoActivator with 0.2% chitosan proved better in the removal of the smear layer when compared to passive ultrasonic irrigation.

A comparative evaluation of shear bond strength of composite resin to pulp chamber dentin treated with sodium thiosulfate and proanthocyanidin: An in vitro study.

AIM: Based on the importance of coronal sealing right after endodontic treatment, this in vitro study aimed to evaluate the difference of shear bond strength to pulp chamber dentin treated with sodium thiosulfate and proanthocyanidin (PA). MATERIALS AND METHODS: Fifteen extracted mandibular molar teeth were decoronated at the level of cementoenamel junction horizontally. The individual teeth were then sectioned mesiodistally to expose the pulp chamber dentin using a diamond disc. The specimens were randomly divided into three groups (n = 10). Group A: control group, treated with 5.25% sodium hypochlorite (NaOCl) for 30 min followed by a final rinse with 17% ethylenediaminetetraacetic acid (EDTA) solution for 3 min; Group B: after pretreatment with NaOCl and EDTA, it is further treated with 5% sodium thiosulfate (Na2S2O3) for 10 min; and Group C: after pretreatment with NaOCl and EDTA, it is further treated with 6.5% PA for 10 min. After drying the specimens, a bonding agent namely One Coat Bond SL (SwissTEC, Coltene) was applied to the pulp chamber dentin followed by a composite restoration (SwissTEC, Coltene). Each specimen was then tested under a universal testing machine at the dentin/resin interface to determine the shear bond strength. RESULTS: Both the groups in which 5% Na2S2O3 and 6.5% PA were used for 10 min showed bond strength that was found to be statistically higher than the positive control (P < 0.05). CONCLUSION: The use of Na2S2O3 and PA can significantly increase the bond strength of composite resin to NaOCl/EDTA-treated dentin, allowing adhesive restorations to be immediately applied after endodontic treatment.

The Contribution of Indian Endodontists in Rotary Endodontics to Pubmed Database, from 2000-2017.

AIM: This study aimed at assessing the trends of publications of Indian Endodontists in the field of rotary Endodontics in the PubMed database from 2000-2017. METHODS: The date of publication was set from 1st January 2000 to 31st December 2017, wherein keywords entered in the advanced search were "Indian" AND "Dental" AND "Rotary Endodontics". From the collected articles the following criteria were noted: year of publication, the name of the journal, status of the journal, name of the first author, state of origin and the rotary Endodontic file system used. RESULTS: All data was subjected for statistical analysis by SPSS software version 16. The data were subjected to chi-square test, and a statistically significant difference (p < 0.001) was obtained in the inter-6 yearly interval starting from 2000-2017; in the status of the journal; the state of origin and in the generation of rotary files which were published during the study period. CONCLUSION: The plethora of publications by Indian Conservative Dentists and Endodontists is on the rise, and with the advent of better technology a greater interest in the mechanics and properties of these rotary file systems has invoked greater research work.

Scanning Electron Microscopic Evaluation of Efficacy of 17% Ethylenediaminetetraacetic Acid and Chitosan for Smear Layer Removal with Ultrasonics: An In vitro Study.

INTRODUCTION: The main aim of root canal treatment is cleaning, shaping and then obturating three dimensionally to prevent reinfection. This includes chemicomechanical cleansing by instrumentation and the use of irrigating solutions. Therefore, the purpose of this study was to compare the smear layer removal from root canal dentine subjected to two root canal irrigants, 17% EDTA and 0.2% Chitosan, a new irrigant using Scanning Electron Microscope. METHODOLOGY: 40 single rooted premolars were decoronated followed by instrumentation with I Race files and intermediate irrigation with 3% sodium hypochlorite and activation with ultrasonics. Then the samples were longitudinally sectioned and place in the respective test solutions and their controls for 5 minutes. Scanning Electron Microscopic evaluation was further carried out. RESULTS: The results of the present study indicates that the Chitosan which was proved effective in removing smear layer. CONCLUSION: A moderate concentration of 0.2% chitosan removes the smear layer with greater efficiency.

Subclinical albuminuria is linked to gray matter atrophy in type 2 diabetes mellitus.

OBJECTIVE: Microalbuminuria (MA), a marker of renal microvascular disease, is associated with brain atrophy and neurovascular changes in older adults with type 2 diabetes mellitus (DM). We evaluated the relationship between urine albumin-to-creatinine ratio (UACR) and regional brain volumes to determine whether subclinical albuminuria may indicate early structural brain changes in type 2 DM. MATERIALS/METHODS: We studied UACR and brain volumes in 85 type 2 DM patients (64.8±8.3years) and 40 age-matched controls using 3D magnetization prepared rapid acquisition with gradient echo (MP-RAGE) MRI (magnetic resonance imaging) at 3 Tesla. The relationship between UACR and brain volumes was analyzed using the least square models. RESULTS: In DM patients, UACR ≥5mg/g, UACR ≥10mg/g and clinically significant MA (UACR ≥17mg/g [males] and 25mg/g [females]) were associated with lower gray matter (GM) volume in the frontal lobe (r(2)adj=0.2-0.4, P=0.01-0.05) and UACR ≥5mg/g was also related to global GM atrophy (r(2)adj=0.1, P=0.04), independent of DM duration, glucose levels, HbA1c and hypertension. For UACR ≥5mg/g, a lower global GM volume was related to worse executive function (P=0.04) in the DM group. No associations were found for UACR (<5mg/g) and controls. CONCLUSIONS: Subclinical albuminuria (UACR ≥5mg/g) is associated with lower GM volume that has clinical impact on cognitive function in older diabetic patients, and these relationships are independent of DM control and hypertension. Therefore, UACR levels may serve as an additional marker of DM-related brain structural changes.

Emergence delirium in children: a randomized trial to compare total intravenous anesthesia with propofol and remifentanil to inhalational sevoflurane anesthesia.

BACKGROUND: Emergence delirium (ED) refers to a variety of behavioral disturbances commonly seen in children following emergence from anesthesia. Vapor-based anesthesia with sevoflurane, the most common pediatric anesthetic technique, is associated with the highest incidence of ED. Propofol has been shown to reduce ED, but these studies have been methodologically limited. OBJECTIVE: To conduct a randomized-controlled trial comparing the incidence of ED in children following sevoflurane (SEVO) anesthesia and propofol-remifentanil total intravenous anesthesia (TIVA). METHODS: One hundred and twelve children, ASA I-II, aged ≥ 2 and ≤ 6 years, undergoing strabismus repair, were assigned to receive TIVA (intravenous induction and maintenance of anesthesia with propofol and remifentanil) or SEVO (inhalational induction and maintenance of anesthesia with sevoflurane). Parent-child induction behavior was scored using the Perioperative Adult Child Behavior Interaction Scale (PACBIS). Postoperatively, ED was assessed by a masked investigator using the Pediatric Anesthesia Emergence Delirium (PAED) Scale and pain using the Face, Legs, Activity, Cry, Consolability (FLACC) Scale every 5 min. RESULTS: Data are reported for 94 subjects. Incidence of ED was higher with SEVO (38.3% vs 14.9%, P = 0.018). There was no difference in the median PACBIS score. A higher FLACC score was seen with SEVO (median 3 vs 1, P = 0.033). Subjects experiencing ED had higher FLACC scores vs those unaffected by ED (median 7 vs 1, P < 0.0001). CONCLUSION: There was a lower incidence of ED after TIVA. Both intravenous and inhalational inductions were similarly well-tolerated. The use of TIVA was associated with reduced postoperative pain as measured using FLACC scores.

The effects of droperidol and ondansetron on dispersion of myocardial repolarization in children.

OBJECTIVES: To compare the effects of droperidol and ondansetron on electrocardiographic indices of myocardial repolarization in children. AIM: To refine understanding of the torsadogenic risk to children exposed to anti-emetic prophylaxis in the perioperative period. BACKGROUND: QT interval prolongation is associated with torsades des pointes (TdP), but is a poor predictor of drug torsadogenicity. Susceptibility to TdP arises from increased transmural dispersion of repolarization (TDR) across the myocardial wall, rather than QT interval prolongation per se. TDR can be measured on the electrocardiogram as the time interval between the peak and end of the T wave (Tp-e). Tp-e may therefore provide a readily available, noninvasive assay of drug torsadogenicity. The perioperative period is one of high risk for TdP in children with or at risk of long QT syndromes. Droperidol and ondansetron are two drugs commonly administered perioperatively, for prophylaxis of nausea and vomiting, which can prolong the QT interval. This study investigated their effects on myocardial repolarization. METHODS: One hundred and eight ASA1-2 children undergoing elective day-case surgery were randomized to receive droperidol, ondansetron, both or neither. Pre- and post-administration 12-lead electrocardiogram (ECGs) were recorded. QT and Tp-e intervals were measured and compared within and between groups, for the primary endpoint of a 25 ms change in Tp-e. RESULTS: Eighty children completed the study. There were no demographic or baseline ECG differences between groups. QT intervals lengthened by 10-17 ms after allocated treatments, with no between-group differences. Values remained within normal limits for all groups. Tp-e intervals increased by 0-7 ms, with no between-group differences. There were no instances of dysrhythmia. CONCLUSIONS: Droperidol and ondansetron, in therapeutic anti-emetic doses, produce equivalent, clinically insignificant QT prolongation and negligible Tp-e prolongation, suggesting that neither is torsadogenic in healthy children at these doses.

The effect of a target controlled infusion of propofol on predictability of recovery from anesthesia in children.

BACKGROUND: Emergence following termination of a general anesthetic depends on the effect site concentration (C(e)) of the drug declining to an awakening value (C(e)-awake). C(e)-awake has been described in adults, but is unknown in children. OBJECTIVES: To determine C(e)-awake in children following a target-controlled infusion (TCI) of propofol and to assess a C(e)-driven TCI system's ability to predict times to emergence from anesthesia. METHODS: Subjects undergoing elective surgery, aged 3 months to <10 years were recruited into three age-stratified groups. A target C(e) of 3-4 microg x ml(-1) was selected for induction and subsequently titrated to patient response and surgical stimulus. Preoperative acetaminophen, a remifentanil infusion and regional anesthesia were permitted for supplemental analgesia. State Entropy (SE) was monitored from induction to emergence. Emergence was defined as the time of first purposeful spontaneous movement (PSM). Time zero was defined as the end of propofol infusion. Based on a pilot study, a C(e)-awake of 1.9 microg x ml(-1) was chosen as the wake-up threshold used by the software to predict emergence times. RESULTS: Data was collected for 90 of 104 recruited patients. PSM occurred at a mean (sd) C(e) of 2.0 (0.5) microg x ml(-1) and an SE of 79 (11). There were no differences between age groups. A wide variation in emergence time was observed, with a mean (sd) of 16.9 (7) min, and a trend to more rapid emergence in older subjects. CONCLUSION: A predicted C(e)-awake of 2.0 microg x ml(-1) in children aged 3 months to <10 years was identified with the selected model. For expert users of propofol in children, during shorter surgical procedures, TCI predicted emergence times do not offer significant clinical advantages.

The effect of age on the dose of remifentanil for tracheal intubation in infants and children.

INTRODUCTION: This study aimed to determine the age-specific bolus dose of remifentanil (ED(50)) to facilitate tracheal intubation without the use of neuromuscular blocking agents. METHODS: ASA 1-2 subjects were recruited into three groups of 0-3 months (group I), 4-12 months (group II), and 1-3 years (group III) of age. A sequential up-and-down design determined the remifentanil bolus dose, which was initially started at 3 mcg x kg(-1) and adjusted in 1 mcg x kg(-1) increments (range 1-6 mcg x kg(-1)). Following pretreatment with glycopyrrolate 10 microg x kg(-1) and an induction dose of propofol 5 mg x kg(-1), remifentanil was administered with a blinded study investigator commencing tracheal intubation after 60 s. After tracheal intubation, the time to return of spontaneous ventilation was measured. Logistic regression was used to predict the ED(50) and ED(95) of remifentanil. RESULTS: Sixty-four subjects were recruited. Tracheal intubation was successful at first attempt in over 90% of subjects in each age group. Satisfactory intubating conditions were achieved in 85%, 63%, and 75% of subjects in groups I, II, and III, respectively. The logistic regression results for ED(50) (95% CI) were 3.1 (2.5-3.8), 3.7 (2.0-5.4), and 3.0 (2.1-3.9) mcg x kg(-1), and ED(95) (95% CI) were 5.0 (3.0-7.0), 9.4 (1.5-17.4), and 5.6 (2.9-8.4) mcg x kg(-1) in groups I, II, and III, respectively. Infants aged 4-12 months (group II) showed a marked variability in dose response; however, the mean ED(50) and ED(95) were not different to groups I and III. Older children had a longer duration of apnea than infants, 331 vs 180 s (P < 0.05). DISCUSSION: The ED(50) of remifentanil for tracheal intubation was higher in all age groups than previously reported. Ideal intubating conditions were achieved in 50% of subjects with remifentanil doses of 3.1-3.7 mcg x kg(-1). Higher doses will be required for higher success rates and with anticholinergic pretreatment, doses of up to 6 mcg x kg(-1) were tolerated, without adverse effects, in two patients. Further investigation of the variability in dose response in infants and assessment of the safety this technique is warranted.

Target controlled infusion for kids: trials and simulations.

Target controlled infusion (TCI) for Kids is a computer controlled system designed to administer propofol for general anesthesia. A controller establishes infusion rates required to achieve a specified concentration at the drug's effect site (C(e)) by implementing a continuously updated pharmacokinetic-pharmacodymanic model. This manuscript provides an overview of the system's design, preclinical tests, and a clinical pilot study. In pre-clinical tests, predicted infusion rates for 20 simulated procedures displayed complete convergent validity between two software implementations, Labview and Matlab, at computational intervals of 5, 10, and 15s, but diverged with 20s intervals due to system rounding errors. The volume of drug delivered by the TCI system also displayed convergent validity with Tivatrainer, a widely used TCI simulation software. Further tests, were conducted for 50 random procedures to evaluate discrepancies between volumes reported and those actually delivered by the system. Accuracies were within clinically acceptable ranges and normally distributed with a mean of 0.08 +/- 0.01 ml. In the clinical study, propofol pharmacokinetics were simulated for 30 surgical procedures involving children aged 3 months to 9 years. Predicted C(e) values during standard clinical practice, the accuracy of wake-up times predicted by the system, and potential correlations between patient wake-up times, C(e), and state entropy (SE) were assessed. Neither Ce nor SE was a reliable predictor of wake-up time in children, but the small sample size of this study does not fully accommodate the noted variation in children's response to propofol. A C(e) value of 1.9 mug/ml was found to best predict emergence from anesthesia in children.