Computational investigation of hysteresis and phase equilibria of n-alkanes in a metal-organic framework with both micropores and mesopores.

Adsorption hysteresis is a phenomenon related to phase transitions that can impact applications such as gas storage and separations in porous materials. Computational approaches can greatly facilitate the understanding of phase transitions and phase equilibria in porous materials. In this work, adsorption isotherms for methane, ethane, propane, and n-hexane were calculated from atomistic grand canonical Monte Carlo (GCMC) simulations in a metal-organic framework having both micropores and mesopores to better understand hysteresis and phase equilibria between connected pores of different size and the external bulk fluid. At low temperatures, the calculated isotherms exhibit sharp steps accompanied by hysteresis. As a complementary simulation method, canonical (NVT) ensemble simulations with Widom test particle insertions are demonstrated to provide additional information about these systems. The NVT+Widom simulations provide the full van der Waals loop associated with the sharp steps and hysteresis, including the locations of the spinodal points and points within the metastable and unstable regions that are inaccessible to GCMC simulations. The simulations provide molecular-level insight into pore filling and equilibria between high- and low-density states within individual pores. The effect of framework flexibility on adsorption hysteresis is also investigated for methane in IRMOF-1.

Shock in Trauma.

Shock is a life-threatening condition of circulatory failure leading to inadequate organ perfusion and tissue oxygenation. In a trauma patient, shock may be due to hypovolemia, cardiogenic, obstructive or distributive causes individually or in combination. The physiological response to major hemorrhage is dependent on a variety of autonomic reflexes, mechanism of injury, bleeding source, and baseline physiology of the patient. This article discusses the common causes of shock and the accompanying physiology, how clinical assessment can support the diagnosis and effective treatment of shock, and the common pitfalls in trauma patients.

Out-of-hospital cardiac arrest due to hanging: a retrospective analysis.

BACKGROUND: There has been little research into the prehospital management of cardiac arrest following hanging despite it being among the most prevalent methods of suicide worldwide. The aim of this study was to report the characteristics, resuscitative treatment and outcomes of patients managed in the prehospital environment for cardiac arrest secondary to hanging and compare these with all-cause out-of-hospital cardiac arrest (OHCA). METHODS: Data from a UK ambulance service cardiac arrest registry were extracted for all cases in which treatment was provided for OHCA due to hanging between 1 January 2013 and 30 June 2018. Cases were linked to outcome data obtained from the Trauma Audit and Research Network. Comparison of the cohort was made to previously published data from a UK study of all-cause OHCA with 95% CIs calculated for the proportional difference between the studies in selected presentation and outcome variables. RESULTS: 189 cases were identified. 95 patients were conveyed to hospital and four of these survived to discharge. 40 patients were conveyed despite absence of a spontaneous circulation and none of these patients survived. While only three patients were initially in a shockable rhythm, DC shocks were administered in 20 cases. There was one case of failed ventilation prompting front-of-neck access for oxygenation. By comparison with all-cause OHCA the proportion of patients with a spontaneous circulation at hospital handover was similar (27.0% vs 27.5%; 0.5% difference, 95% CI -5.9% to 6.8%, p=0.882) but survival to hospital discharge was significantly lower (2.2% vs 8.4%; 6.2% difference, 95% CI 4.1% to 8.3%, p=0.002). CONCLUSION: Clinical outcomes following OHCA due to hanging are poor, particularly when patients are transported while in cardiac arrest. Failure to ventilate was uncommon, and clinicians should be alert to the possibility of shockable rhythms developing during resuscitation.

Geo-temporal provision of pre-hospital emergency anaesthesia by UK Helicopter Emergency Medical Services: an observational cohort study.

BACKGROUND: Pre-hospital emergency anaesthesia (PHEA) is frequently required for injured patients. National Institute for Health and Care Excellence (NICE) quality standards state that PHEA should be delivered within 45 min of an emergency call. We investigated whether there is geo-temporal variation in service provision to the UK population. METHODS: We retrospectivly audited the time of day when PHEA is provided by UK Helicopter Emergency Medical Services (HEMS), by recording PHEA provision on a randomly selected week and weekend day in 2018. Pre-hospital emergency anaesthesia in the United Kingdom: an observational cohort study retrospectively assessed the time from emergency call to pre-hospital emergency anaesthesia delivery by HEMS during a 1 yr period from April 2017 to March 2018. The population coverage likely to receive pre-hospital emergency anaesthesia in accord with NICE guidelines was estimated by integrating population data with the median time to PHEA, hours of service provision, geographic location, and transport modality. RESULTS: On a weekday 20 HEMS units (comprising from four to 31 enhanced care teams) were estimated to be able to meet NICE guidelines for delivery of PHEA to a poulation of 6.6-35.2 million individuals (at times of minimum and maximal staffing, respectively). At the weekend, 17 HEMS units (comprising from 5 to 28 enhanced care teams) were estimated to be able to meet NICE guidelines for PHEA deliveryto a population of 6.8-34.1 million individuals (minimum and maximal staffing, respectively). CONCLUSIONS: There is marked geo-temporal variation in the ability of HEMS organisations to deliver pre-hospital emergency anaesthesia in the UK.

The experiences of health care professionals, patients, and families of the process of referral and admission to intensive care: A systematic literature review.

Treatment in an intensive care unit can be life-saving but it can be distressing and not every patient can benefit. Decisions to admit a patient to an intensive care unit are complex. We wished to explore how the decision to refer or admit is experienced by those involved, and undertook a systematic review of the literature to answer the research question: What are the experiences of health care professionals, patients, and families, of the process of referral and admission to an intensive care unit? Twelve relevant studies were identified, and a thematic analysis was conducted. Most studies involved health care professionals, with only two considering patients' or families' experiences. Four themes were identified which influenced experiences of intensive care unit referral and review: the professional environment; communication; the allocation of limited resources; and acknowledging uncertainty. Patients' and families' experiences have been under-researched in this area.

Toxic inhalational injury.

A middle-aged patient presented with toxic inhalational injury, and was resuscitated prehospitally and treated in the emergency department for smoke inhalation, carbon monoxide (CO) exposure and cyanide poisoning with the use of antidotes. Due to the CO effects on spectrophotometry, an anaemia initially identified on blood gas analysis was thought to be artefactual, but was later confirmed by laboratory testing to be accurate. In addition, cyanide can confound haemoglobin testing due to its use in the analytical process and non-cyanide analysis is required when there is suspected exposure. Although no consensus exists on a first-line cyanide antidote choice, hydroxocobalamin is the only antidote without a serious side effect profile and/or deleterious cardiovascular effects. We propose prehospital enhanced care teams consider carrying hydroxocobalamin for early administration in toxic inhalational injury.

Pre-hospital emergency anaesthesia in the United Kingdom: an observational cohort study.

BACKGROUND: Up to one in eight trauma patients arrive at a hospital with a partially or completely obstructed airway. The UK National Institute for health and Care Excellence (NICE) practice guidelines recommend that trauma patients requiring anaesthesia for definitive airway management receive this care within 45 min of an emergency call, preferably at the incident scene. How frequently this target is achieved remains unclear. We assessed the recorded time to pre-hospital emergency anaesthesia after trauma across UK helicopter emergency medical service (HEMS) units. METHODS: We retrospectively recorded time to pre-hospital emergency anaesthesia across all 20 eligible UK HEMS units (comprising 52 enhanced care teams) from April 1, 2017 to March 31, 2018. Times recorded for emergency notification, dispatch, arrival, and neuromuscular blocking agent administration were analysed. RESULTS: HEMS undertook 1755 pre-hospital emergency anaesthetics for trauma across the UK during the study period. There were 1176/1755 (67%) episodes undertaken by helicopter response teams during daylight hours. The median time to pre-hospital emergency anaesthesia was 55 min (inter-quartile range: 45-70); anaesthesia within 45 min of the initial emergency call was achieved in 25% cases. Delayed dispatch time (>9 min) was associated with fewer patients receiving pre-hospital anaesthesia within 45 min (odds ratio: 7.7 [95% confidence intervals: 5.8-10.1]; P<0.0001). CONCLUSIONS: The time to achieve pre-hospital emergency anaesthesia by UK HEMS frequently exceeds the recommended 45 min target. Reducing the time to dispatch of emergency medical teams may impact on the delivery of pre-hospital emergency anaesthesia.

Chemical stabilization of the extracellular matrix attenuates growth of experimentally induced abdominal aorta aneurysms in a large animal model.

OBJECTIVE: The goal of the present study was to test the safety and efficacy of chemical stabilization of the arterial extracellular matrix as a novel nonoperative treatment of abdominal aortic aneurysms (AAAs) in a clinically relevant large animal model. METHODS: To achieve matrix stabilization, we used 1,2,3,4,6-pentagalloylglucose (PGG), a noncytotoxic polyphenolic agent capable of binding to and stabilizing elastin and collagen against the action of degrading enzymes. We first optimized the therapeutic PGG formulation and time of exposure by in vitro testing on porcine aortas using phenol histologic staining with iron chloride, elastic recoil assays, and PGG quantification as a function of tissue thickness. We then induced AAAs in 16 swine using sequential balloon angioplasty and elastase/collagenase and calcium chloride treatment of the infrarenal segment. We monitored AAA induction and development using digital subtraction angiography. At 2 weeks after induction, after the AAAs had reached ∼66% arterial expansion, the swine were randomly assigned to 2 groups. In the treatment group, we delivered PGG to the aneurysmal aorta endoluminally using a weeping balloon and evaluated the AAA diameters using digital subtraction angiography for another 10 weeks. The control swine did not receive any treatment. For the safety evaluation, we collected blood and performed comprehensive metabolic panels and complete blood counts every 2 to 3 weeks for all the animals. The swine were routinely monitored for neurologic and physical attributes such as behavior, inactivity, alertness, appetite, discomfort, and weight gain. After euthanasia and full necropsy, we analyzed the AAA tissue samples for PGG content, elastic recoil, and histologic features. RESULTS: In vitro, a single 2.5-minute intraluminal delivery of 0.3% PGG to the swine aorta was sufficient for PGG to diffuse through the entire thickness of the porcine arterial tissues and to bind with high affinity to the elastic lamellae, as seen by positive iron chloride staining, a reduction of elastic recoil, and an increase in PGG content. In vivo, the control swine AAA tissues were thickened and showed the typical aspects of AAA, including chronic inflammation, adventitial reactivity, smooth muscle cell proliferation, elastic lamellae degradation, and medial and adventitial calcification. Similar aspects were noted in the PGG-treated arteries, except for the lack of calcification and an apparent diminished hyperplasia. PGG treatment was effective in reducing AAA expansion and reversing the process of AAA dilation by reducing the aortic diameters to ≤30% by week 12 (P < .05). PGG was specifically localized to the aneurysmal segments as seen by histologic examination, the reduction of elastic recoil, and an increase in PGG content. PGG treatment did not affect the swine's neurologic or physical attributes, weight, blood chemistry, blood cells, or functionality of remote organs. The control, untreated swine exhibited progressive increases in AAA diameters up to a mean value of 104%. CONCLUSIONS: Localized delivery of PGG to the aneurysmal aorta attenuated AAA growth and reversed the course of the disease in the swine AAA model. Such specificity for diseased tissue is unprecedented in nonoperative AAA treatment. This novel paradigm-shifting approach has the potential to revolutionize AAA management and save thousands of lives.

United Kingdom Survey of Culture-Negative Peritonitis and Dialysate Sampling Practice.

Peritonitis is a major cause of technique failure in peritoneal dialysis (PD) and accurate diagnosis ensures successful management and avoids unnecessary antibiotic exposure. United Kingdom (UK) registry data on peritonitis rates are not routinely reported. We conducted an electronic survey amongst senior PD nurses and microbiologists to obtain information about PD effluent sampling and processing practices in the UK. The survey was completed by 53 of 79 centres (67% response rate). The median annual culture-negative rate was 15% (range 5 - 38%). The main findings were wide variation in reported sampling volumes and processing methods that may in part explain the variation in culture-negative rates. Adherence to guidelines might reduce culture-negative rates informed by reporting data into national registries.

Broadband acoustic properties of a murine skull.

It has been well recognized that the presence of a skull imposes harsh restrictions on the use of ultrasound and optoacoustic techniques in the study, treatment and modulation of the brain function. We propose a rigorous modeling and experimental methodology for estimating the insertion loss and the elastic constants of the skull over a wide range of frequencies and incidence angles. A point-source-like excitation of ultrawideband acoustic radiation was induced via the absorption of nanosecond duration laser pulses by a 20 µm diameter microsphere. The acoustic waves transmitted through the skull are recorded by a broadband, spherically focused ultrasound transducer. A coregistered pulse-echo ultrasound scan is subsequently performed to provide accurate skull geometry to be fed into an acoustic transmission model represented in an angular spectrum domain. The modeling predictions were validated by measurements taken from a glass cover-slip and ex vivo adult mouse skulls. The flexible semi-analytical formulation of the model allows for seamless extension to other transducer geometries and diverse experimental scenarios involving broadband acoustic transmission through locally flat solid structures. It is anticipated that accurate quantification and modeling of the skull transmission effects would ultimately allow for skull aberration correction in a broad variety of applications employing transcranial detection or transmission of high frequency ultrasound.

Effects of the murine skull in optoacoustic brain microscopy.

Despite the great promise behind the recent introduction of optoacoustic technology into the arsenal of small-animal neuroimaging methods, a variety of acoustic and light-related effects introduced by adult murine skull severely compromise the performance of optoacoustics in transcranial imaging. As a result, high-resolution noninvasive optoacoustic microscopy studies are still limited to a thin layer of pial microvasculature, which can be effectively resolved by tight focusing of the excitation light. We examined a range of distortions introduced by an adult murine skull in transcranial optoacoustic imaging under both acoustically- and optically-determined resolution scenarios. It is shown that strong low-pass filtering characteristics of the skull may significantly deteriorate the achievable spatial resolution in deep brain imaging where no light focusing is possible. While only brain vasculature with a diameter larger than 60 µm was effectively resolved via transcranial measurements with acoustic resolution, significant improvements are seen through cranial windows and thinned skull experiments.

Volumetric tracking of migratory melanophores during zebrafish development by optoacoustic microscopy.

Unveiling mechanisms driving specification, recruitment and regeneration of melanophores is key in understanding melanin-related disorders. This study reports on the applicability of a hybrid focus optoacoustic microscope (HFOAM) for volumetric tracking of migratory melanophores in developing zebrafish. The excellent contrast from highly-absorbing melanin provided by the method is shown to be ideal for label-free dynamic visualization of melanophores in their unperturbed environment. We established safe laser energy levels that enable high-contrast longitudinal tracking of the cells over an extended period of developmental time without causing cell toxicity or pigment bleaching. Owing to its hybrid optical and acoustic resolution, the new imaging technique can be seamlessly applied for noninvasive studies of both optically-transparent larval as well as adult stages of the zebrafish model organism, which is not possible using other optical microscopy methods.

Improved optoacoustic microscopy through three-dimensional spatial impulse response synthetic aperture focusing technique.

Synthetic aperture focusing technique (SAFT) is effective in restoring lateral resolution of ultrasonic images for scans with focusing-related distortions. Although successfully applied in pulse-echo ultrasonics, the physical nature of an optoacoustic modality requires a modified algorithm to return accurate results. The SIR-SAFT method reported here uses the spatial impulse response (SIR) of the transducer to weight the contributions to the SAFT and is tailored to provide significant resolution and signal gains for out-of-focus sources in scanning optoacoustic microscopy systems. Furthermore, the SIR-SAFT is implemented in full three dimensions, applicable to signals both far of and at the focus of the ultrasonic detector. The method has been further shown to outperform conventional SAFT algorithms for both simulated and experimental optoacoustic data.

Functional real-time optoacoustic imaging of middle cerebral artery occlusion in mice.

BACKGROUND AND PURPOSE: Longitudinal functional imaging studies of stroke are key in identifying the disease progression and possible therapeutic interventions. Here we investigate the applicability of real-time functional optoacoustic imaging for monitoring of stroke progression in the whole brain of living animals. MATERIALS AND METHODS: The middle cerebral artery occlusion (MCAO) was used to model stroke in mice, which were imaged preoperatively and the occlusion was kept in place for 60 minutes, after which optoacoustic scans were taken at several time points. RESULTS: Post ischemia an asymmetry of deoxygenated hemoglobin in the brain was observed as a region of hypoxia in the hemisphere affected by the ischemic event. Furthermore, we were able to visualize the penumbra in-vivo as a localized hemodynamically-compromised area adjacent to the region of stroke-induced perfusion deficit. CONCLUSION: The intrinsic sensitivity of the new imaging approach to functional blood parameters, in combination with real time operation and high spatial resolution in deep living tissues, may see it become a valuable and unique tool in the development and monitoring of treatments aimed at suspending the spread of an infarct area.

Tri-component, mobile bearing, total ankle replacement: mid-term functional outcome and survival.

Tri-component, mobile bearing, uncemented, total ankle replacements were introduced after the high failure rates of cemented, highly constrained, first-generation, total ankle replacement implants. A total of 30 primary total ankle replacements in 29 patients (20 males and 9 females) were followed up in the present retrospective study for up to 13 (mean 5.1 ± 4) years. The postoperative functional and radiographic outcomes were measured. Failure was defined as revision of either of the components for any reason or conversion of the total ankle replacement to arthrodesis because of debilitating pain that did not resolve after surgery. Of the 29 patients, 2 underwent revision and 1 underwent arthrodesis. All 3 patients had the malpositioned talar implant revised. The mean American Orthopaedic Foot and Ankle Society score was 81 at 1 year postoperatively. Revision of the tibial or talar component for any reason or conversion of the ankle replacement to arthrodesis was considered failure for the survival analysis. Kaplan-Meier analysis showed a 5-year survival rate of 87.6%. The last failure occurred 23.3 months after surgery.

Possible tropical lakes on Titan from observations of dark terrain.

Titan has clouds, rain and lakes--like Earth--but composed of methane rather than water. Unlike Earth, most of the condensable methane (the equivalent of 5 m depth globally averaged) lies in the atmosphere. Liquid detected on the surface (about 2 m deep) has been found by radar images only poleward of 50° latitude, while dune fields pervade the tropics. General circulation models explain this dichotomy, predicting that methane efficiently migrates to the poles from these lower latitudes. Here we report an analysis of near-infrared spectral images of the region between 20° N and 20° S latitude. The data reveal that the lowest fluxes in seven wavelength bands that probe Titan's surface occur in an oval region of about 60 × 40 km(2), which has been observed repeatedly since 2004. Radiative transfer analyses demonstrate that the resulting spectrum is consistent with a black surface, indicative of liquid methane on the surface. Enduring low-latitude lakes are best explained as supplied by subterranean sources (within the last 10,000 years), which may be responsible for Titan's methane, the continual photochemical depletion of which furnishes Titan's organic chemistry.

An unusual case of severe high anion gap metabolic acidosis.

We present a case of high anion gap metabolic acidosis with an unusual aetiology in a 75-year-old lady with hypoglycaemia, encephalopathy and relatively preserved renal function. Full toxicology and biochemical analysis suggested that she had an inborn error of metabolism, riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency that can predispose to severe acidosis in situations where calorific intake is reduced. We believe this to be one of the few published cases and is remarkable for the presentation in late adulthood in addition to the requirement for emergency haemodialysis due to the severity of the metabolic disturbance.