Simulation of Aerosol and Droplet Spread during Upper Airway and Gastrointestinal Endoscopy.

BACKGROUND AND AIMS: Aerosols and droplets are the main vectors in transmission of highly contagious SARS-CoV-2. Invasive diagnostic procedures like upper airway and gastrointestinal endoscopy have been declared as aerosol-generating procedures. Protection of healthcare workers is crucial in times of the COVID-19 pandemic. METHODS: We simulated aerosol and droplet spread during upper airway and gastrointestinal endoscopy with and without physico-mechanical barriers using a simulation model. RESULTS: A clear plastic drape as used for central venous access markedly reduced visualized aerosol and droplet spread during endoscopy. CONCLUSION: A simple and cheap drape has the potential to reduce aerosol and droplet spread during endoscopy. In terms of healthcare worker protection, this may be important particularly in low- or moderate-income countries.

Outcome of kidney transplantations from ≥65-year-old deceased donors with acute kidney injury.

Kidney transplantation (KT) from donors with acute kidney injury (AKI) has been associated with delayed graft function (DGF) but similar graft survival compared with KT from donors without AKI. Kidneys from ≥65-year-old donors with comorbidities are more susceptible to cold ischemia time (CIT) and DGF and it is unknown whether such elderly kidneys with AKI can also be transplanted with satisfactory outcomes. All KTs from ≥65-year-old donors performed at our center from 1999 to 2019 (n = 233) were retrospectively analyzed and short- as well as long-term outcomes were compared for KTs from donors with (n = 64) and without AKI (n = 169). There were no significant differences regarding the frequency of DGF as well as the estimated glomerular filtration rate (eGFR) 1 and 3 years post-transplant between the no-AKI and the AKI group (DGF: no-AKI 30.2% vs. AKI 40.6%, P = .17; eGFR at 1-year: 31.9 ml/min/1.73 m2 vs. 35.5 ml/min/1.73 m2 , P = .32; at 3-years: 33.8 ml/min/1.73 m2 vs. 40.9 ml/min/1.73 m2 , P = .18; respectively). Death-censored graft survival and patient survival were also not significantly different. Multivariable Cox regression analysis did not identify AKI as a significant risk factor for graft loss or death. Following careful donor and recipient selection, kidneys from ≥65-year-old AKI donors may potentially be transplanted with satisfactory outcomes.

Impact of the explanting surgeon's impression of donor arteriosclerosis on outcome of kidney transplantations from donors aged ≥65 years.

PURPOSE: Careful donor selection is important for kidney transplantations (KT) from suboptimal donors aged ≥65 years. Several tools such as histopathological assessment of preimplant biopsies have been shown to predict allograft survival and can be applied for selection. Whether the explanting surgeon's appraisal is associated with outcomes of KTs from suboptimal donors is unknown. METHODS: We compared outcomes of KTs from ≥65-year-old deceased donors performed at our centre between 1999 and 2018 for which grading of macroscopic 'donor arteriosclerosis' (n=104) and 'organ quality' (n=208) as judged by the explanting surgeon and documented on the Eurotransplant kidney organ report was available. RESULTS: No association was observed between degree of macroscopic donor arteriosclerosis and death-censored graft survival in univariable or multivariable regression analyses. Compared to KTs from donors with no/mild arteriosclerosis, KTs from donors with moderate/severe arteriosclerosis were associated with a significantly impaired allograft function 3 months, 1 year and 3 years after transplantation (e.g. at 3 years: 176.8 µmol/l vs 137.0 µmol/l, P=0.003). Following multivariable regression analysis, these differences remained significant at 3 months and 3 years after KT. No association was observed between degree of macroscopic arteriosclerosis and mortality or primary non-function as well as no consistent association with delayed graft function and histological arteriosclerosis. Assessment of 'organ quality' was not associated with outcomes. CONCLUSION: Our data suggest that the explanting surgeon's assessment of donor arteriosclerosis is associated with allograft function. Larger studies and better standardization of kidney inspection after explantation are required to further explore the impact of surgeon's appraisal in KT.

Leg-heel chest compression as an alternative for medical professionals in times of COVID-19.

OBJECTIVE: To evaluate leg-heel chest compression without previous training as an alternative for medical professionals and its effects on distance to potential aerosol spread during chest compression. METHODS: 20 medical professionals performed standard manual chest compression followed by leg-heel chest compression after a brief instruction on a manikin. We compared percentage of correct chest compression position, percentage of full chest recoil, percentage of correct compression depth, average compression depth, percentage of correct compression rate and average compression rate between both methods. In a second approach, potential aerosol spread during chest compression was visualized. RESULTS: Our data indicate no credible difference between manual and leg-heel compression. The distance to potential aerosol spread could have been increased by leg-heel method. CONCLUSION: Under special circumstances like COVID-19-pandemic, leg-heel chest compression may be an effective alternative without previous training compared to manual chest compression while markedly increasing the distance to the patient.

Characteristics of Double-Lumen Tubes Determine Bronchial Airway Pressure.

OBJECTIVES: To determine pressure-flow characteristics of double-lumen tubes (DLTs) with an outer diameter of 26 to 41 French and calculate bronchial pressure in a model setup and using data from patients who underwent one-lung ventilation with a DLT. DESIGN: Prospective experimental study and retrospective analysis of clinical measurements. SETTING: University medical center. PARTICIPANTS: Lung model and patients. INTERVENTIONS: Flow rates and pressure gradients across Robertshaw-type DLTs (∆P(DLT)) were measured in a physical model and the DLT-specific resistance coefficients were calculated from ∆P(DLT) according to Rohrer's approach. Bronchial pressure was calculated from airway pressure and ∆P(DLT) in a lung model and using data from 72 patients who underwent thoracic surgery and direct bronchial pressure measurements. MEASUREMENTS AND MAIN RESULTS: ∆P(DLT) increased with decreasing outer diameter of the DLT and more than doubled during one- compared with two-lung ventilation (p<0.001). ∆P(DLT) differed between inspiration and expiration (p<0.05) and was higher across the tracheal lumen compared with the bronchial lumen (p<0.001). Root mean square differences between calculated and measured bronchial pressures were less than 0.7 cmH2O in the lung model and less than 1.2 cmH2O in the clinical measurements. CONCLUSIONS: The DLTs' pressure-flow characteristics differed considerably depending on size, mode of ventilation (one or two lung), direction of flow, and lumen for ventilation. Rohrer's approach allowed for sufficient calculation of the bronchial airway pressure during both one- and two-lung ventilation.

Beliefs, preferences, and acceptance of personal protective equipment for a shock room team in a tertiary care center.

BACKGROUND: During coronavirus disease of 2019 pandemic a standard usage of personal protective equipment (PPE) in healthcare was mandatory, while actually the usage of PPE is currently decreasing. This raises the question about the further use of PPE in the clinical setting because healthcare workers (HCW) are at greater risk of being infected with SARS-CoV-2 than the general population. The primary objective of this study is to determine the proportion of shock room team members approving the further use of PPE including a FFP2 respirator in simulation training and reality. The secondary objectives are to describe the expertise and difficulties faced while using PPE in the shock room care. METHODS: Fifty-four HCW participated in a shock room simulation training at a large urban tertiary care hospital in Germany, utilizing a PPE comprising an FFP2 mask, gloves, goggles, and gown. Subsequently, participants completed an online questionnaire featuring 15 questions presented on a 5-point Likert scale or as multiple-choice questions with predefined answers. RESULTS: Sixty-eight point five percent of our participants voted for an established standard PPE in shock room care. The largest fraction of our participants (40.7%) favors a standard PPE consisting of FFP2 mask, gown, and gloves. Less HCW (31.5%) want to wear PPE in shock room simulation training. Except for goggles we could not detect relevant difficulties faced while using PPE in the shock room environment. Incorrect use of PPE was observed in 14.8%. CONCLUSION: A majority of our participants favored a standard PPE including a FFP2 respirator in shock room care. In addition, we recommend the use of PPE in shock room simulation training, while further awareness of and training in proper use of PPE seems to be necessary to reduce risk of infectious diseases for HCW.

Implementing an interprofessional point-of-care ultrasound protocol for dyspneic patients in an emergency department as a blended learning concept-Feasibility of Employing Thoracic Ultrasound in Shortness of Breath.

Objective: Dyspnea is a common symptom in the Emergency Department, with a wide variety of differential diagnoses. Previous research has demonstrated the diagnostic accuracy of Point-of-Care Ultrasound (POCUS) in this field of interest. Our goal was to better establish sonography in our emergency department with a practicable and time effective method. Therefore, we implemented a sonography protocol in an interprofessional emergency team using blended learning as a modern didactic approach and evaluated the learning and teaching success. We named the study FETUS, which stands for "Feasibility of Employing Thoracic Ultrasound in Shortness of Breath." Methods: A demonstration of the POCUS protocol was given, followed by individual supervision during clinical routine. A written manual, a pocket card, and further materials for personal training supplemented the training. A post-training questionnaire measured several parameters regarding the training, e.g., subjective skill-acquisition or media use. Results: 32 medical and nursing staff participated in this study, 14 of whom completed the questionnaire. All training modalities offered were well received. A pre-post comparison of subjective sonographic competence shows a significant increase in both medical and nursing staff.The other items surveyed also indicate the success of the intervention undertaken. Conclusion: The use of different media as a blended learning approach can support the implementation of new measures in the ongoing working routine within an interprofessional team.

Weaning assessment of veno-arteriovenous (V-AV) extracorporeal membrane oxygenation (ECMO).

Currently, there is a lack of methods for simultaneous assessment of readiness for decannulation of the veno-venous (V-V) and veno-arterial (V-A) components during veno-arteriovenous (V-AV) extracorporal membrane oxygenation (ECMO) support. We describe a novel approach using a simultaneous off-sweep and controlled backflow test to assess readiness for decannulation from V-AV ECMO. This method needs testing in future clinical trials.

Mechanisms of limitation of oxygen delivery during veno-venous extracorporal membrane oxygenation.

Delivery of oxygen to the mitochondrium is a process involving multiple steps. We here present the integration of the mechanisms of oxygen delivery (DO2) during veno-venous (V-V) extracorporal membrane oxygenation (ECMO) into a holistic physiological model. The final steps of oxygen transport in this model are the convective transport of oxygen bound to hemoglobin in the arterial blood and the diffusion to the mitochondrium from the microcirculation. Limitation of DO2 may occur on both steps. In cases of severe respiratory failure without lung function, ECMO may provide the entire oxygen supply for the patients. If the cardiac output (CO) is significantly higher than the maximal ECMO flow, the addition of deoxygenated venous blood will lead to a low arterial oxygen saturation (SaO2). In this situation the convective transport of oxygen is mostly limited by the maximal ECMO flow. If a bi-caval dual lumen cannula is used, the recirculation may be very low. Lowering the CO in this situation will increase the arterial SaO2. An increased arterial SaO2 may increase the oxygen transport to the mitochondrium by diffusion. The hypothesis derived from this model is that lowering the CO during V-V ECMO support in the situation described above might increase DO2 to the tissues by improving oxygen diffusion.

[Recommendations for Education in Sonography in Prehospital Emergency Medicine (pPOCUS): Consensus paper of DGINA, DGAI, BAND, BV-ÄLRD, DGU, DIVI and DGIIN]. / Empfehlungen zur Sonografieausbildung in der prähospitalen Notfallmedizin (pPOCUS): Konsensuspapier von DGINA, DGAI, BAND, BV-ÄLRD, DGU, DIVI und DGIIN.

Point-of-care sonography is a precondition in acute and emergency medicine for the diagnosis and initiation of therapy for critically ill and injured patients. While emergency sonography is a mandatory part of the training for clinical acute and emergency medicine, it is not everywhere required for prehospital emergency medicine. Although some medical societies in Germany have already established their own learning concepts for emergency ultrasound, a uniform national training concept for the use of emergency sonography in the out-of-hospital setting is still lacking. Experts of several professional medical societies have therefore joined forces and developed a structured training concept for emergency sonography in the prehospital setting. The consensus paper serves as quality assurance in prehospital emergency sonography.

[Recommendations for Education in Sonography in Prehospital Emergency Medicine (pPOCUS): Consensus paper of DGINA, DGAI, BAND, BV-ÄLRD, DGU, DIVI and DGIIN]. / Empfehlungen zur Sonografieausbildung in der prähospitalen Notfallmedizin (pPOCUS): Konsensuspapier von DGINA, DGAI, BAND, BV-ÄLRD, DGU, DIVI und DGIIN.

Point-of-care sonography is a precondition in acute and emergency medicine for the diagnosis and initiation of therapy for critically ill and injured patients. While emergency sonography is a mandatory part of the training for clinical acute and emergency medicine, it is not everywhere required for prehospital emergency medicine. Although some medical societies in Germany have already established their own learning concepts for emergency ultrasound, a uniform national training concept for the use of emergency sonography in the out-of-hospital setting is still lacking. Experts of several professional medical societies have therefore joined forces and developed a structured training concept for emergency sonography in the prehospital setting. The consensus paper serves as quality assurance in prehospital emergency sonography.

Improving Emergency Department Patient-Physician Conversation Through an Artificial Intelligence Symptom-Taking Tool: Mixed Methods Pilot Observational Study.

BACKGROUND: Establishing rapport and empathy between patients and their health care provider is important but challenging in the context of a busy and crowded emergency department (ED). OBJECTIVE: We explore the hypotheses that rapport building, documentation, and time efficiency might be improved in the ED by providing patients a digital tool that uses Bayesian reasoning-based techniques to gather relevant symptoms and history for handover to clinicians. METHODS: A 2-phase pilot evaluation was carried out in the ED of a German tertiary referral and major trauma hospital that treats an average of 120 patients daily. Phase 1 observations guided iterative improvement of the digital tool, which was then further evaluated in phase 2. All patients who were willing and able to provide consent were invited to participate, excluding those with severe injury or illness requiring immediate treatment, with traumatic injury, incapable of completing a health assessment, and aged <18 years. Over an 18-day period with 1699 patients presenting to the ED, 815 (47.96%) were eligible based on triage level. With available recruitment staff, 135 were approached, of whom 81 (60%) were included in the study. In a mixed methods evaluation, patients entered information into the tool, accessed by clinicians through a dashboard. All users completed evaluation Likert-scale questionnaires rating the tool's performance. The feasibility of a larger trial was evaluated through rates of recruitment and questionnaire completion. RESULTS: Respondents strongly endorsed the tool for facilitating conversation (61/81, 75% of patients, 57/78, 73% of physician ratings, and 10/10, 100% of nurse ratings). Most nurses judged the tool as potentially time saving, whereas most physicians only agreed for a subset of medical specialties (eg, surgery). Patients reported high usability and understood the tool's questions. The tool was recommended by most patients (63/81, 78%), in 53% (41/77) of physician ratings, and in 76% (61/80) of nurse ratings. Questionnaire completion rates were 100% (81/81) by patients and 96% (78/81 enrolled patients) by physicians. CONCLUSIONS: This pilot confirmed that a larger study in the setting would be feasible. The tool has clear potential to improve patient-health care provider interaction and could also contribute to ED efficiency savings. Future research and development will extend the range of patients for whom the history-taking tool has clinical utility. TRIAL REGISTRATION: German Clinical Trials Register DRKS00024115; https://drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00024115.

Avoiding being stung or bitten - prey capture behaviors of the ant-eating Texas horned lizard (Phrynosoma cornutum).

Horned lizards (Phrynosoma) are specialized predators, including many species that primarily feed on seed harvester ants (Pogonomyrmex). Harvester ants have strong mandibles to husk seeds or defensively bite, and a venomous sting. Texas horned lizards possess a blood plasma factor that neutralizes harvester ant venom and produce copious mucus in the pharynx and esophagus, thus embedding and incapacitating swallowed ants. We used high-speed video recordings to investigate complexities of their lingual prey capture and handling behavior. Lizards primarily strike ants at their mesosoma (thorax plus propodeum of abdomen). They avoid the head and gaster, even if closer to the lizard, and if prey directional movement is reversed. Orientation of captured ants during retraction is with head first (rostral), thus providing initial mucus coating of the mandibles. Prey capture accuracy and precise handling illustrates the specificity of adaptations of horned lizards in avoiding harm, and the challenges lizards face when feeding on dangerous prey.

Exploration of strategies to reduce aerosol-spread during chest compressions: A simulation and cadaver model.

OBJECTIVE: To evaluate the effect of strategies to reduce the spread of simulated aerosol during chest compressions on manikin and cadaver experimental models. METHODS: To evaluate aerosol-spread we nebulized ultraviolet sensitive detergents into the artificial airway of a resuscitation dummy and performed CPR. The spread of the visualized aerosol was documented by a camera. In a further approach we applied nebulized detergents into the airways of human cadavers and detected the simulated spread on the same way. Among others we did recordings with undergoing compression-only-CPR, with a surgical mask or an oxygen mask on the patients face and with an inserted supraglottic airway device with and without a connected airway filter. RESULTS: Most aerosol-spread at the direction of the provider was visualized during compression-only-CPR. The use of a surgical mask and of an oxygen mask on the patient's face deflected the spread. Inserting a supraglottic airway device connected to an airway filter lead to a remarkable reduction of aerosol-spread. CONCLUSION: The early insertion of a supraglottic airway device connected to an airway filter before starting chest compression may be beneficial for staff protection during CPR.

Retinotectal ganglion cells in the zebrafish, Danio rerio.

The morphology of retinotectal ganglion cells was investigated by retrograde transport of dextran amines applied into the optic tectum in vitro. Based on criteria such as stratification pattern and size of the dendritic processes, as well as the shape and position of the soma within the dendritic field, three main groups of ganglion cell types with a total of nine different types were identified. The first group included monostratified cells, of which two types (Ma(2) and Mb(5)) may be ON- and OFF-variants, and the third (Mb(6)) had its dendritic field as a narrow band at the inner border of the inner plexiform layer. These three cells had the largest dendritic fields, with areas exceeding 40,000 microm(2). In two additional monostratified cells the dendrites were spread over the entire width of either sublamina a or sublamina b of the inner plexiform layer (Ma, Mb). They were of intermediate size with mean dendritic field areas between 10,000 and 20,000 microm(2). The second group contained two types of bistratified cells (Bb(4/5) and Bb(4,5/5,6)) with two distinct bands of dendritic stratifications in sublamina b. One of them had the smallest dendritic field (below 5,000,mm(2)) of all cell types in the sample. The diffuse cells of the third group had their dendrites across the entire width of the inner plexiform layer. The sample of retinotectal cells investigated in this study included types described previously (Mangrum et al. [2002] Vis Neurosci 19:767-779) but also new types not described previously.

Gradual photochemical-induced conversion of liquid polydimethylsiloxane layers to carbon containing silica coatings by VUV irradiation at 172 nm.

Thin liquid layers of polydimethylsiloxane (PDMS) were irradiated by VUV light under nitrogen atmosphere using a Xe(2)- excimer lamp. The irradiated layers were analyzed with infrared reflection absorption spectroscopy (IRRAS) and X-ray photoelectron spectroscopy (XPS), showing a gradual photochemical-induced conversion of the liquid PDMS to solid SiO(2)-like coatings. IRRAS measurements revealed a smooth frequency shift of the maximal absorption band from 1111 to 1231 cm(-1) with increasing irradiation energy density caused by a gradual shift from the asymmetric Si-O stretching vibration of PDMS to the longitudinal optical (LO) mode of SiO(2). The shift was found to be dependent on the applied irradiation energy density and the O/Si ratio in the film analyzed by XPS measurements. The atomic ratio of O/Si increases from 1:1 to about 2.5:1. At the same time, the atomic ratio of C/Si decreases from 2:1 down to 1:6.5. Images taken by high resolution field emission scanning electron microscopy (FESEM) and scanning force microscopy (SFM) show a smooth surface without cracks or pores. The controllable coating properties in combination with the possibility for local irradiation using masks are promising high potential for the coating technology.

Visual accommodation in vertebrates: mechanisms, physiological response and stimuli.

The mechanism and stimulation of the accommodative reflex in vertebrate eyes are reviewed. Except for lampreys, accommodation is brought about by intraocular muscles that mediate either a displacement or deformation of the lens, a change of the corneal radius of curvature or a combination of these mechanisms. Elasmobranchs have little accommodation and are emmetropic in water rather than hyperopic as commonly stated. Accommodation in teleosts and amphibians is well understood and achieved by lens displacement. The accommodative mechanism of amniotes is of considerable diversity and reflects different lifestyles rather than phylogenetical relationships. In all amniotes, the ciliary muscle never has a direct impact on the lens. It relaxes the tension applied to the lens by zonular fibers and/or ligaments. In birds and reptiles the ciliary muscle is usually split into two parts, of which the anterior portion changes the corneal radius of curvature. The deformation of the lens is generally achieved either by its own elasticity (humans, probably other mammals and sauropsids) or by the force of circular muscle fibers in the iris (reptiles, birds, aquatic mammals). In the second part of the paper, some of the current hypotheses about the accommodative stimulus are reviewed together with physiological response characteristics.

The cone photoreceptors and visual pigments of chameleons.

Visual pigments, oil droplets and photoreceptor types in the retinas of four species of true chameleons have been examined by microspectrophotometry. The species occupy different photic environments: two species of Chamaeleo are from Madagascar and two species of Furcifer are from Africa and the Arabian Peninsula. In addition to double cones, four spectrally distinct classes of single cone were identified. No rod photoreceptors were observed. The visual pigments appear to be mixtures of rhodopsins and porphyropsins. Double cones contained a pale oil droplet in the principle member and both outer segments contained a long-wave-sensitive visual pigment with a spectral maximum between about 555 nm and 610 nm, depending on the rhodopsin/porphyropsin mixture. Long-wave-sensitive single cones contained a visual pigment spectrally identical to the double cones, but combined with a yellow oil droplet. The other three classes of single cone contained visual pigments with maxima at about 480-505, 440-450 and 375-385 nm, combined with yellow, clear and transparent oil droplets respectively. The latter two classes were sparsely distributed. The transmission of the lens and cornea of C. dilepis was measured and found to be transparent throughout the visible and near ultraviolet, with a cut off at about 350 nm.

Displaced retinal ganglion cells project to the accessory optic system in the chameleon ( Chamaeleo calyptratus).

Retinal ganglion cells were successfully labelled in the chameleon by retrograde axonal transport of dextran amines that were applied to the nucleus of the basal optic root (nBOR) in an in vitro preparation. Labelled ganglion cells were restricted to the contralateral eye. Many cells were completely stained including their dendritic trees. With few exceptions, all cells had displaced somata that were located at the inner margin of the inner nuclear layer. The labelled ganglion cells had two to six primary dendrites that branched frequently and formed large unistratified dendritic trees within sublamina 1 of the inner plexiform layer. There was extensive overlap of the dendritic trees of neighbouring cells leading to an estimated coverage factor of 2-4. The dendritic field areas varied in size according to the retinal position of the cells and were highest in the central retina around the fovea with a maximum of 0.14 mm(2) and reached a second maximum at the retinal margin with values of 0.08-0.1 mm(2). The smallest dendritic areas (0.04-0.06 mm(2)) were measured midway between the fovea and retinal margin. The size of the soma area was not correlated to the dendritic field size and increased from 100 to 150 microm(2) near the fovea to 150-300 microm(2) at the retinal margin. There was no evidence for a retinotopic organisation of ganglion cell fibres within the nBOR. All cells were of uniform morphology that was identical to the type of nBOR-projecting displaced ganglion cell (DGC) described previously for the bird retina. Similar to birds, the labelled DGCs were the only source of retinal projection to the nBOR. A small fraction of cells had orthotopic somata located in the ganglion cell layer but were otherwise identical to the labelled DGCs. The similarity of chameleon nBOR-projecting ganglion cells to those described in avian retinas mirrors the close phylogenetic relationship of birds and lizards.