Rapid Administration of Ketamine for Abscess Drainage in Children-A Dose Finding Study.

STUDY OBJECTIVE: To estimate the minimum dose and total sedation time of rapidly infused ketamine that achieves 3 to 5 minutes of effective sedation in children undergoing abscess incision and drainage in the emergency department. METHODS: The Up-Down method was used to estimate the dose of intravenous ketamine infused over 5 seconds or less that provided effective sedation in 50% (ED50) and 95% (ED95) for healthy children aged 2 to 5 years and 6 to 11 years undergoing abscess incision and drainage. None were pretreated with opioids. Three investigators blinded to ketamine dose independently graded sedation effectiveness by viewing a video recording of the first 5 minutes of sedation. Recovery was determined when patients reached a Modified Aldrete score of 10. RESULTS: We enrolled 20 children in each age group. The estimated ED50 was 0.9 and 0.6 mg/kg for the 2 to 5 years and 6 to 11 years' groups and the estimated ED95 was 1.1 mg/kg for both groups. The median time to full recovery for the 2 groups was 20.5 and 17.5 minutes when only 1 dose of ketamine was administered and 27.5 and 35 minutes when additional doses of ketamine were administered. No participants experienced serious adverse events. CONCLUSIONS: We estimated ED50 and ED95 for rapidly infused ketamine for 2 age groups undergoing abscess incision and drainage. Further studies are needed to get a more precise estimate of ED95. The total sedation time with this technique in the abscess group was shorter than most previous studies and is consistent with our previous observations in patients undergoing fracture reduction.

Socioeconomic and psychosocial factors are associated with poor treatment outcomes in Australian adults living with HIV: a case-control study.

Background A substantial minority of patients living with HIV refuse or cease antiretroviral therapy (ART), have virological failure (VF) or develop an AIDS-defining condition (ADC) or serious non-AIDS event (SNAE). It is not understood which socioeconomic and psychosocial factors may be associated with these poor outcomes. METHODS: Thirty-nine patients with poor HIV treatment outcomes, defined as those who refused or ceased ART, had VF or were hospitalised with an ADC or SNAE (cases), were compared with 120 controls on suppressive ART. A self-report survey recorded demographics, physical health, life stressors, social supports, HIV disclosure, stigma or discrimination, health care access, treatment adherence, side effects, health and treatment perceptions and financial and employment status. Socioeconomic and psychosocial covariates significant in bivariate analyses were assessed with conditional multivariable logistic regression, adjusted for year of HIV diagnosis. RESULTS: Cases and controls did not differ significantly with regard to sex (96.2% (n = 153) male) or age (mean (± s.d.) 51 ± 11 years). Twenty cases (51%) had refused or ceased ART, 35 (90%) had an HIV viral load >50 copies mL-1, 12 (31%) were hospitalised with an ADC and five (13%) were hospitalised with a new SNAE. Three covariates were independently associated with poor outcomes: foregoing necessities for financial reasons (adjusted odds ratio (aOR) 3.1, 95% confidence interval (95% CI) 1.3-7.6, P = 0.014), cost barriers to accessing HIV care (aOR 3.1, 95% CI 1.0-9.6, P = 0.049) and lower quality of life (aOR 3.8, 95% CI 1.5-9.7, P = 0.004). CONCLUSIONS: Despite universal health care, socioeconomic and psychosocial factors are associated with poor HIV outcomes in adults in Australia. These factors should be addressed through targeted interventions to improve long-term successful treatment.

Gelation, Phase Separation, and Fibril Formation in Aqueous Hydroxypropylmethylcellulose Solutions.

The thermoresponsive behavior of a hydroxypropylmethylcellulose (HPMC) sample in aqueous solutions has been studied by a powerful combination of characterization tools, including rheology, turbidimetry, cryogenic transmission electron microscopy (cryoTEM), light scattering, small-angle neutron scattering (SANS), and small-angle X-ray scattering (SAXS). Consistent with prior literature, solutions with concentrations ranging from 0.3 to 3 wt % exhibit a sharp drop in the dynamic viscoelastic moduli G' and G″ upon heating near 57 °C. The drop in moduli is accompanied by an abrupt increase in turbidity. All the evidence is consistent with this corresponding to liquid-liquid phase separation, leading to polymer-rich droplets in a polymer-depleted matrix. Upon further heating, the moduli increase, and G' exceeds G″, corresponding to gelation. CryoTEM in dilute solutions reveals that HPMC forms fibrils at the same temperature range where the moduli increase. SANS and SAXS confirm the appearance of fibrils over a range of concentration, and that their average diameter is ca. 18 nm; thus gelation is attributable to formation of a sample-spanning network of fibrils. These results are compared in detail with the closely related and well-studied methylcellulose (MC). The HPMC fibrils are generally shorter, more flexible, and contain more water than with MC, and the resulting gel at high temperatures has a much lower modulus. In addition to the differences in fibril structure, the key distinction between HPMC and MC is that the former undergoes liquid-liquid phase separation prior to forming fibrils and associated gelation, whereas the latter forms fibrils first. These results and their interpretation are compared with the prior literature, in light of the relatively recent discovery of the propensity of MC and HPMC to self-assemble into fibrils on heating.

A comparison of seminal hepatitis C virus (HCV) RNA levels during recent and chronic HCV infection in HIV-infected and HIV-uninfected individuals.

BACKGROUND: We aimed to characterize seminal hepatitis C virus (HCV) RNA dynamics in human immunodeficiency virus (HIV)-positive men with acute HCV infection given its potential role in sexual transmission of HCV. METHODS: Men with acute HCV infection (duration, ≤12 months) or chronic HCV infection (duration, >12 months) were prospectively recruited. Paired semen and blood samples were assayed for HCV RNA levels. Results were analyzed using χ(2), Fisher exact, Mann-Whitney U, and Kruskal-Wallis tests. RESULTS: Eighteen men (27.3%) had acute HCV and HIV coinfection, 22 (33.3%) had chronic HCV infection and HIV coinfection, and 26 (39.4%) had chronic HCV monoinfection. HCV RNA was detected in semen specimens from 29 of 66 men (43.9%). The median HCV RNA level in blood was 4.0 log IU/mL higher than that in semen. HCV RNA levels were correlated in semen and blood (r(2) = 0.142). Neither HIV positivity nor acute HCV infection was associated with an increased frequency of seminal HCV RNA detection. Among men with acute HCV and HIV coinfection, the median HCV RNA level in blood specimens from those with seminal HCV RNA was higher than that in blood specimens from those without seminal HCV RNA (P = .001). Seminal HCV RNA was detected in ≥1 sample for 26 of 35 men (74.3%) attending follow up. CONCLUSIONS: HCV RNA was detected in semen during both acute and chronic HCV infection. This was unaffected by HIV positivity or the phase of HCV infection. Elevated seminal HCV RNA levels could contribute to sexual transmission of HCV, but other factors, including high-risk behaviors, may be the main drivers for HCV transmission in HIV-infected individuals.

Single-Tablet Emtricitabine-Rilpivirine-Tenofovir as HIV Postexposure Prophylaxis in Men Who Have Sex With Men.

BACKGROUND: Completion rates for human immunodeficiency virus (HIV) postexposure prophylaxis (PEP) are low. We investigated the adherence and safety of coformulated emtricitabine (FTC), rilpivirine (RPV), and tenofovir disoproxil fumarate (TDF) as a 3-drug, single-tablet regimen for PEP in men who have sex with men (MSM). METHODS: In an open-label, single-arm study at 2 public sexual health clinics and 2 hospital emergency departments in urban Australia, 100 HIV-uninfected MSM requiring 3-drug PEP received single-tablet FTC-RPV-TDF once daily for 28 days. The primary endpoint was premature PEP cessation or primary HIV infection through week 12. Additional endpoints were adherence (by self-report of doses missed or not ingested with a meal, by pill count, and by plasma concentrations of tenofovir and FTC at week 4); and safety (clinical and laboratory adverse events [AEs]). RESULTS: PEP completion was 92% (95% confidence interval, 85%-96%); premature cessation resulted from loss to follow-up (6%), AEs (1%), or study burden (1%). No participant was found to acquire HIV through week 12. Adherence was 98.6% (standard deviation [SD], 2.4) by pill count and 98.5% (SD, 2.7) by self-report; 86% reported taking all doses with food, and 88% of the subset tested had plasma tenofovir levels suggesting full adherence (>40 ng/mL). Eighty-eight participants experienced at least 1 clinical AE; 4 had grade 3 AEs or higher, possibly attributable to study drug. Fifty-six participants experienced at least 1 laboratory AE; 4 had AEs of grade 3 or higher, possibly attributable to study drug. CONCLUSIONS: A single-tablet regimen of FTC-RPV-TDF was well tolerated as once-daily PEP, with high levels of adherence and completion. CLINICAL TRIALS REGISTRATION: NCT01715636.

Rapid administration technique of ketamine for pediatric forearm fracture reduction: a dose-finding study.

STUDY OBJECTIVE: We estimate the minimum dose and total sedation time of rapidly infused ketamine that achieves 3 to 5 minutes of effective sedation in children undergoing forearm fracture reduction in the emergency department. METHODS: We used the up-down method to estimate the median dose of intravenous ketamine infused during less than or equal to 5 seconds that provided effective sedation in 50% (ED50) and 95% (ED95) of healthy children aged 2 to 5, 6 to 11, or 12 to 17 years who were undergoing forearm fracture reduction. Most patients were pretreated with opioids. Three investigators blinded to ketamine dose independently graded sedation effectiveness by viewing a video recording of the first 5 minutes of sedation. Recovery was assessed by modified Aldrete score. RESULTS: We enrolled 20 children in each age group. The estimated ED50 was 0.7, 0.5, and 0.6 mg/kg and the estimated ED95 was 0.7, 0.7, and 0.8 mg/kg for the groups aged 2 to 5, 6 to 11, and 12 to 17 years, respectively. For the group aged 2 to 5 years, an empirically derived ED95 was 0.8 mg/kg. All patients who received the empirically derived ED95 in the group aged 2 to 5 years or the estimated ED95 in the groups aged 6 to 11 and 12 to 17 years had effective sedation. The median total sedation time for the 3 age groups, respectively, was 25, 22.5, and 25 minutes if 1 dose of ketamine was administered and 35, 25, and 45 minutes if additional doses were administered. No participant experienced serious adverse events. CONCLUSION: We estimated ED50 and ED95 for rapidly infused ketamine for 3 age groups undergoing fracture reduction. Total sedation time was shorter than that in most previous studies.

Difficult airway consultation service for children: steps to implement and preliminary results.

BACKGROUND: Failed airway management remains one of the most common causes of cardiopulmonary arrest in the pediatric population. Practice guidelines addressing the difficult airway (DAW) in adults provide anesthesiologists a framework for managing the airway during the perioperative period; however, similar consensus guidelines are lacking in the pediatric population. Many of the adverse events associated with difficult pediatric airway management occur outside the perioperative setting and often result in worse outcomes. The lower frequency of DAW management required in children, lesser awareness of pediatric health care professionals about DAW management, and the need for guiding principles led us to develop a DAW consultative service. This report outlines the steps to establish the Difficult Airway Service (DAS) and the initial experiences with this new consultation service. METHODS: The mission of the DAS is to identify children with known or anticipated DAWs, communicate the diagnosis and collaborate with referring medical and surgical services, and to manage children in those settings that airway management might be required in the context of the patient's ongoing medical care. RESULTS: The initial 3-month experience confirmed that a majority of pediatric DAW events are associated with congenital or acquired abnormalities. Through appropriate consultation and leadership, the DAS was able to physically and electronically identify pediatric patients with a DAW and provide management. Hospital-wide participation was instrumental in the success and exponential growth of DAS: planned preoperative tracheostomy in complicated posterior spinal fusion candidates, participation in EXIT procedures, standardization of airway carts, and implementation of education forums. CONCLUSION: In developing the DAS, our goal was to provide a more comprehensive approach to caring for a child with a DAW that included their entire hospital stay and follow-up care. We believe this approach has improved health care professional awareness as well as the safe management of routine and difficult pediatric airway. Additional studies are needed to determine whether measurable changes in morbidity and mortality are observed over time.

Fibrillar structure of methylcellulose hydrogels.

It is well established that aqueous solutions of methylcellulose (MC) can form hydrogels on heating, with the rheological gel point closely correlated to the appearance of optical turbidity. However, the detailed gelation mechanism and the resulting gel structure remain poorly understood. Herein the fibrillar structure of aqueous MC gels was precisely quantified with a powerful combination of (real space) cryogenic transmission electron microscopy (cryo-TEM) and (reciprocal space) small-angle neutron scattering (SANS) techniques. The cryo-TEM images reveal that MC chains with a molecular weight of 300 000 g/mol associate into fibrils upon heating, with a remarkably uniform diameter of 15 ± 2 nm over a range of concentrations. Vitrified gels also exhibit heterogeneity in the fibril density on the length scale of hundreds of nanometers, consistent with the observed optical turbidity of MC hydrogels. The SANS curves of gels exhibit no characteristic peaks or plateaus over a broad range of wavevector, q, from 0.001-0.2 Å(-1). The major feature is a change in slope from I ∼ q(-1.7) in the intermediate q range (0.001 - 0.01 Å(-1)) to I ∼ q(-4) above q ≈ 0.015 Å(-1). The fibrillar nature of the gel structure was confirmed by fitting the SANS data consistently with a model based on the form factor for flexible cylinders with a polydisperse radius. This model was found to capture the scattering features quantitatively for MC gels varying in concentration from 0.09-1.3 wt %. In agreement with the microscopy results, the flexible cylinder model indicated fibril diameters of 14 ± 1 nm for samples at elevated temperatures. This combination of complementary experimental techniques provides a comprehensive nanoscale depiction of fibrillar morphology for MC gels, which correlates very well with macro-scale rheological behavior and optical turbidity previously observed for such systems.

Tswanarising global gayness: the 'unAfrican' argument, Western gay media imagery, local responses and gay culture in Botswana.

This paper is a strategic intervention in the debate over the value of globalised gay identity for emerging sexual minority communities in the South. Focusing on self-identifying gay men in Botswana using semi-structured interviews, it explores their views of what characterises 'modern gay culture' and relates these to international media clichés of a glamorous, stylish, hedonistic gayness. I argue that identifying with what is so visibly a Western image of gayness exposes sexual minority communities to the most dangerous of the justifications for homophobia in Africa, the argument that sexual dissidence is a neo-colonial conspiracy to subvert 'African values'. The 'unAfrican' argument has to be taken very seriously, not only because it taps into the intense, conflicted emotions at the heart of the post-colonial condition, but also because it contains an undeniable germ of truth. This poses a dilemma, since global gay discourses, including the media clichés, are an important source of inspiration for African sexual minorities. A communication activism strategy is proposed to undermine the unAfrican argument by cultivating and asserting the 'tswanarisation' of gay culture in Botswana that is already taking place. A similar strategy may also be effective in other African societies.

Optimised EMG pipeline for gesture classification.

In the expanding field of robotic prosthetics, surface electromyography (sEMG) signals can be decoded to seamlessly control a robotic prosthesis to perform the desired gesture. It is essential to create a pipeline, which can acquire, process, and accurately classify sEMG signals in order to replicate the desired hand gesture in near real-time and in a reliable manner. In this study, an optimised pipeline is proposed. This pipeline encompasses the main stages of sEMG signal processing and hand gesture classification and implements a sliding window approach, which is the main focus of the optimisation. In this study, a range of different parameters and modelling approaches are evaluated. The main contributions of this work are a robust and extensive analysis of sliding window parameter selection and an optimised pipeline that could be implemented in practice with minimal overheads. The optimum pipeline is efficient and achieves accurate prediction of hand gestures with an uninterrupted processing pipeline.

Consensus-based recommendations for standardizing terminology and reporting adverse events for emergency department procedural sedation and analgesia in children.

Children commonly require sedation and analgesia for procedures in the emergency department. Establishing accurate adverse event and complications rates from the available literature has been difficult because of the difficulty in aggregating results from previous studies that have used varied terminology to describe the same adverse events and outcomes. Further, serious adverse events occur infrequently, necessitating the study of large numbers of children to assess safety. These limitations prevent the establishment of a sufficiently large database on which evidence-based practice guidelines may be based. We assembled a panel of pediatric sedation researchers and experts to develop consensus-based recommendations for standardizing procedural sedation and analgesia terminology and reporting of adverse events. Our goal was to create a uniform reporting mechanism for future studies to facilitate the aggregation and comparison of results.

Pediatric laryngeal dimensions: an age-based analysis.

BACKGROUND: In children, the cricoid is considered the narrowest portion of the "funnel-shaped" airway. Growth and development lead to a transition to the more cylindrical adult airway. A number of airway decisions in pediatric airway practice are based on this transition from the pediatric to the adult airway. Our primary aim in this study was to measure airway dimensions in children of various ages. The measures of the glottis and cricoid regions were used to determine whether a transition from the funnel-shaped pediatric airway to the cylindrical adult airway could be identified based on images obtained from video bronchoscopy. METHODS: One hundred thirty-five children (ASA physical status 1 or 2) aged 6 mo to 13 yr were enrolled for measurement of laryngeal dimensions, including cross-sectional area (G-CSA), anteroposterior and transverse diameters at the level of the glottis and the cricoid (C-CSA), using the video bronchoscopic technique under general anesthesia. RESULTS: Of the 135 children enrolled in the study, seven patients were excluded from the analysis mainly because of poor image quality. Of the 128 children studied (79 boys and 49 girls), mean values (+/-standard deviation) for the demographic data were age 5.9 (+/-3.3) yr, height 113.5 (+/-22.2) cm and weight 23.5 (+/-13) kg. Overall, the mean C-CSA was larger than the G-CSA (48.9 +/- 15.5 mm(2) vs 30 +/- 16.5 mm(2), respectively). This relationship was maintained throughout the study population starting from 6 mo of age (P < 0.001, r = 0.45, power = 1). The mean ratio for C-CSA: G-CSA was 2.1 +/- 1.2. There was a positive correlation between G- and the C-CSA versus age (r = 0.36, P < 0.001; r = 0.27, P = 0.001, respectively), height (r = 0.34, P < 0.001; r = 0.29, P < 0.001, respectively), and weight (r = 0.35, P < 0.001; r = 0.25, P = 0.003, respectively). No significant gender differences in the mean values of the studied variables were observed. CONCLUSION: In this study of infants and children, the glottis rather than cricoid was the narrowest portion of the pediatric airway. Similar to adults, the pediatric airway is more cylindrical than funnel shaped based on these video bronchoscopic images. Further studies are needed to determine whether these static airway measurements in anesthetized and paralyzed children reflect the dynamic characteristics of the glottis and cricoid in children.

Upper airway dimensions in children using rigid video-bronchoscopy and a computer software: description of a measurement technique.

BACKGROUND: Pediatric airway management decisions are based primarily on results derived from indirect measures of laryngeal and tracheal dimensions. More recent methods could provide more direct information about absolute and relative changes in airway dimensions associated with growth and development. STUDY OBJECTIVES: The aims of this study were (i) to determine whether a 'video-bronchoscopic' measurement method could be used to reliably measure airway dimensions in children and (ii) to provide a preliminary assessment of dimensions of the glottis and cricoid in children of various ages. METHODS: Following approval from the institutional review board, validation experiments were performed to determine whether measurements obtained from the video image from the bronchoscope provided accurate measurements of tubular objects of known dimensions. The reliability of the measurements was determined by using two independent trained observers to measure video-bronchoscopic images of the larynx at the level of the glottis and the cricoid in 11 children. The observers measured the video-bronchoscopic images and airway measurements were obtained in 16 additional children to determine the utility of the measurement method. RESULTS: There was good agreement between the direct and video-bronchoscopic measurement techniques (Bland and Altman plot) for both the cross-sectional area (CSA) and the diameter of objects. The interobserver measures for cricoid and glottis were reproducible as indicated by the concordance correlation coefficient (CCC) for cricoid anteroposterior diameter (CCC = 0.98, r = 0.98, accuracy = 0.99) and transverse diameter (CCC = 0.93, r = 0.8, accuracy = 0.99) as well as for the glottic anteroposterior diameter (r = 0.8, accuracy = 0.8, CCC = 0.6) and the glottic transverse diameter(r = 0.8, accuracy = 0.74, CCC = 0.6). Overall, for the 27 children studied [mean age 73 months (+/-24.7, range 30-140], the mean value of the cricoid CSA [45.3 mm(2) (+/-13.9)] was found to be greater than the glottic CSA [16.2 mm(2) (+/-10.1)]. CONCLUSIONS: The video-bronchoscopic imaging method provided an accurate, reliable measure of pediatric airway dimensions. This technique could be applied to assess absolute and relative airway size associated with growth and development. The relationship between glottic and cricoid dimensions during growth and development in children needs further investigation across various age groups.

Dolutegravir with tenofovir disoproxil fumarate-emtricitabine as HIV postexposure prophylaxis in gay and bisexual men.

OBJECTIVES: Completion rates for HIV postexposure prophylaxis (PEP) are often low. We investigated the adherence and safety of dolutegravir (DTG; 50 mg daily) with tenofovir disoproxil fumarate-emtricitabine (TDF-FTC; 300/200 mg, respectively) as three-drug PEP in gay and bisexual men. DESIGN: Open-label, single-arm study at three sexual health clinics and two emergency departments in Australia. METHODS: In total, 100 HIV-uninfected gay and bisexual men requiring PEP received DTG and TDF-FTC for 28 days. The primary end point was PEP failure (premature PEP cessation or primary HIV infection through week 12). Additional end points were adherence by self-report (n = 98) and pill count (n = 55), safety, and plasma drug levels at day 28. RESULTS: PEP completion was 90% (95% confidence interval 84-96%). Failures (occurring at a median 9 days, interquartile range 3-16) comprised loss to follow-up (9%) and adverse event resulting in study drug discontinuation (headache, 1%). No participant was found to acquire HIV through week 12. Adherence to PEP was 98% by self-report and in the 55 participants with corresponding pill count data. The most common clinical adverse events were fatigue (26%), nausea (25%), diarrhoea (21%), and headache (10%). There were only four grade 3-4 subjective adverse events. The most common laboratory adverse event was raised alanine aminotransferase (22%), but there was no case of clinical hepatitis. At day 28, the mean estimated glomerular filtration rate decrease was 14 ml/min/1.73m (SD 17, P = 0.001); an estimated glomerular filtration rate of less than 60 ml/min/1.73m occurred in 3%. CONCLUSIONS: DTG with TDF-FTC is a well tolerated option for once-daily PEP.

Socioeconomic factors explain suboptimal adherence to antiretroviral therapy among HIV-infected Australian adults with viral suppression.

BACKGROUND: Missing more than one tablet of contemporary antiretroviral therapy (ART) per month increases the risk of virological failure. Recent studies evaluating a comprehensive range of potential risk factors for suboptimal adherence are not available for high-income settings. METHODS: Adults on ART with undetectable viral load (UDVL) were recruited into a national, multi-centre cohort, completing a comprehensive survey assessing demographics, socio-economic indicators, physical health, well-being, life stressors, social supports, HIV disclosure, HIV-related stigma and discrimination, healthcare access, ART regimen, adherence, side effects, costs and treatment beliefs. Baseline data were assessed, and suboptimal adherence was defined as self-reported missing ≥1 ART dose/month over the previous 3-months; associated factors were identified using bivariate and multivariate binary logistic regression. RESULTS: We assessed 522 participants (494 [94.5%] men, mean age = 50.8 years, median duration UDVL = 3.3 years [IQR = 1.2-6.8]) at 17 sexual health, hospital, and general practice clinics across Australia. Seventy-eight participants (14.9%) reported missing ≥1 dose/month over the previous three months, which was independently associated with: being Australian-born (AOR [adjusted odds ratio] = 2.4 [95%CI = 1.2-4.9], p = 0.014), not being in a relationship (AOR = 3.3 [95%CI = 1.5-7.3], p = 0.004), reaching the "Medicare safety net" (capping annual medical/pharmaceutical costs) (AOR = 2.2 [95%CI = 1.1-4.5], p = 0.024), living in subsidised housing (AOR = 2.5 [95%CI = 1.0-6.2], p = 0.045), receiving home-care services (AOR = 4.4 [95%CI = 1.0-18.8], p = 0.046), HIV community/outreach services linkage (AOR = 2.4 [95%CI = 1.1-5.4], p = 0.033), and starting ART following self-request (AOR = 3.0 [95%CI = 1.3-7.0], p = 0.012). CONCLUSIONS: In this population, 15% reported recent suboptimal ART adherence at levels associated in prospective studies with subsequent virological failure, despite all having an undetectable viral load. Associations were with social/economic/cultural/patient engagement factors, but not ART regimen/clinical factors. These associations may help identify those at higher risk of future virological failure and guide patient education and support.

Sedation and anesthesia protocols used for magnetic resonance imaging studies in infants: provider and pharmacologic considerations.

Most studies report the efficacy of only a single drug to achieve sedation in a broad age range of children. In clinical practice, a variety of sedative and anesthetic regimes are monitored by nurses and physicians. In this study we report the efficacy of a tiered approach to monitoring and sedation in infants. Two-hundred-fifty-eight infants who required magnetic resonance imaging (MRI) studies received either oral chloral hydrate (n = 102) or bolus doses of IV pentobarbital (n = 67) monitored by nurses or IV propofol infusion (n = 68) titrated by physicians. Fewer cardiorespiratory events were observed in the chloral hydrate group (2.9%) compared to pentobarbital (13.4%) and propofol groups (13.6%); P < 0.05, propofol versus chloral hydrate. Infants who received propofol were ready to begin MRI scanning earlier (mean 9.1 +/- 6.7 min) than infants who received oral chloral hydrate (mean 23.5 +/- 13.4 min; P < 0.05). The time to discharge was longest in the pentobarbital (mean 80.3 +/- 39.2 min) and shortest in the propofol group (mean 53.9 +/- 30.1 min; P < 0.05). Infants in the chloral hydrate group moved more frequently (22.5%) during MRI scanning (with four sedation failures of 102) compared to 12.2% in the pentobarbital group and 1.4% in the propofol group (P < 0.001).

Linear and Nonlinear Rheological Behavior of Fibrillar Methylcellulose Hydrogels.

Cryogenic transmission electron microscopy and small-angle neutron scattering recently have revealed that the well-known thermoreversible gelation of methylcellulose (MC) in water is due to the formation of fibrils, with a diameter of 15 ± 2 nm. Here we report that both the linear and nonlinear viscoelastic response of MC solutions and gels can be described by a filament-based mechanical model. In particular, large-amplitude oscillatory shear experiments show that aqueous MC materials transition from shear thinning to shear thickening behavior at the gelation temperature. The critical stress at which MC gels depart from the linear viscoelastic regime and begin to stiffen is well predicted from the filament model over a concentration range of 0.18-2.0 wt %. These predictions are based on fibril densities and persistence lengths obtained experimentally from neutron scattering, combined with cross-link spacings inferred from the gel modulus via the same model.

Clinical Insights Into Foveal Morphology in Albinism.

PURPOSE: A hallmark of albinism is foveal hypoplasia. However, literature suggests variable foveal development. This study evaluates the association between ocular phenotype and foveal morphology to demonstrate the broad structural and functional spectrum. METHODS: Best-corrected visual acuity (BCVA), nystagmus, angle kappa, stereoacuity, iris transillumination, macular melanin presence, foveal avascular zone, and annular reflex were recorded in 14 patients with albinism. Spectral-domain optical coherence tomography provided macular images. RESULTS: The clinical phenotype was broad, with BCVA varying from 20/20 to 20/100. Better BCVA was associated with a preserved foveal avascular zone, annular macular reflex, stereoacuity, and macular melanin. Imaging demonstrated a continuum of foveal development correlating with BCVA. Individuals with a rudimentary pit had normal inner and outer segment lengthening and better BCVA. CONCLUSIONS: The spectrum of ocular structure and visual function in albinism is broad, suggesting a possible diagnosis of albinism in a patient with an even more normal clinical presentation.

Midazolam with ketamine: Who benefits?

[Kennedy RM, McAllister JD. Midazolam with ketamine: who benefits? Ann Emerg Med . March 2000;35:297-299.].