Heart rate and QRS duration as biomarkers predict the immediate outcome from pulseless electrical activity

Introduction Pulseless electrical activity (PEA) is commonly observed in in-hospital cardiac arrest (IHCA). Universally available ECG characteristics such as QRS duration (QRSd) and heart rate (HR) may develop differently in patients who obtain ROSC or not. The aim of this study was to assess prospectively how QRSd and HR as biomarkers predict the immediate outcome of patients with PEA. Method We investigated 327 episodes of IHCA in 298 patients at two US and one Norwegian hospital. We assessed the ECG in 559 segments of PEA nested within episodes, measuring QRSd and HR during pauses of compressions, and noted the clinical state that immediately followed PEA. We investigated the development of HR, QRSd, and transitions to ROSC or no-ROSC (VF/VT, asystole or death) in a joint longitudinal and competing risks statistical model. Results Higher HR, and a rising HR, reflect a higher transition intensity (“hazard”) to ROSC (p < 0.001), but HR was not associated with the transition intensity to no-ROSC. A lower QRSd and a shrinking QRSd reflect an increased transition intensity to ROSC (p = 0.023) and a reduced transition intensity to no-ROSC (p = 0.002). Conclusion HR and QRSd convey information of the immediate outcome during resuscitation from PEA. These universally available and promising biomarkers may guide the emergency team in tailoring individual treatment.publishedVersio

Current induced drag forces on cultivated sugar kelp

To obtain more knowledge of current induced drag forces on sugar kelp, towing tests with ropes containing cultivated sugar kelp was conducted. As freshwater may damage the kelp and cause changes in its mechanical response, tests were performed in a test facility containing seawater. A special purpose test rig was constructed for towing of ropes at different constant velocities through the water, thus simulating water current. The ropes were mounted horizontally and perpendicular to the towing direction. Several ropes, all 3 meters long, with either a medium level or high level of growth, were tested individually. The ropes with sugar kelp were collected from a seaweed farm prior to the experiments and tested with the kelp still attached to the ropes on which they were grown. The total drag forces on the ropes were measured along with the towing velocity. Based on the results from the experiments relations between drag forces, measured size, weight of the kelp and current velocity were found. The results also show signs of reconfiguration of the plants, i.e. adaption to the current flow to reduce the experienced loads. As a result, a power function with an exponent smaller than 2 can be used for modelling of the drag forces. The drag force seems to go towards a value proportional to the velocity squared for higher velocities, indicating that the plants might no longer be able to reduce the forces through reconfiguration. Results from this study expand the knowledge of drag forces on ropes with cultivated sugar kelp and may be implemented into a suitable numerical code for estimation of hydrodynamic loads on seaweed farms.acceptedVersio

Hydrodynamic Loads on Net Panels With Different Solidities

Drag forces on nets represent the largest contribution to hydrodynamic loads on traditional fish farms, and will have a large impact on total loads on new designs utilizing netting as containment method. Precise methods for estimation of drag loads are needed. This paper gives new knowledge on hydrodynamic forces acting on aquaculture nets. It presents results from towing tests, including updated drag and lift coefficients for Raschel knitted netting materials used in nets for aquaculture, and quantify wake effect. The results include high solidity nets and high towing velocities. It was found that drag loads were close to proportional with the netting solidity for netting solidities ranging from 0.15 to 0.32. The wake effect is quantified through the average velocity reduction factor, which is given as a linear function of solidity. Much of previously published data are close to the data found through these tests. However, for high solidity nets, the deviation is significant. Therefore, previously published data and models may overestimate drag loads for high solidity nets

Current induced drag forces on cultivated sugar kelp

To obtain more knowledge of current induced drag forces on sugar kelp, towing tests with ropes containing cultivated sugar kelp was conducted. As freshwater may damage the kelp and cause changes in its mechanical response, tests were performed in a test facility containing seawater. A special purpose test rig was constructed for towing of ropes at different constant velocities through the water, thus simulating water current. The ropes were mounted horizontally and perpendicular to the towing direction. Several ropes, all 3 meters long, with either a medium level or high level of growth, were tested individually. The ropes with sugar kelp were collected from a seaweed farm prior to the experiments and tested with the kelp still attached to the ropes on which they were grown. The total drag forces on the ropes were measured along with the towing velocity. Based on the results from the experiments relations between drag forces, measured size, weight of the kelp and current velocity were found. The results also show signs of reconfiguration of the plants, i.e. adaption to the current flow to reduce the experienced loads. As a result, a power function with an exponent smaller than 2 can be used for modelling of the drag forces. The drag force seems to go towards a value proportional to the velocity squared for higher velocities, indicating that the plants might no longer be able to reduce the forces through reconfiguration. Results from this study expand the knowledge of drag forces on ropes with cultivated sugar kelp and may be implemented into a suitable numerical code for estimation of hydrodynamic loads on seaweed farms

Radiopaque dyes allow vessel imaging in lung tissue using laboratory phase contrast micro-CT

Phase contrast micro-CT is a powerful technique allowing imaging of soft tissue at synchrotrons or using lab- oratory sources. The use of contrast agents is a useful approach when imaging vascular structures. However, common x-ray contrast agents typically rely on heavy metals to increase absorption, which may affect the phase contrast and cause artifacts in the reconstructed volumes. Thus, utilizing an agent with lower attenuation similar to soft tissue is clearly advantageous. Here, we evaluated different colored radiopaque solutions (tissue marking dyes) which had been injected into the vascular system of bovine lung samples, prior to embedding in paraffin. Scans were performed using a micro-focus x-tube calibrated to 10 µm spot size at 70 kV and a photon counting detector with a silicon sensor and 75 µm pixels. The resulting volumes have a voxel size of (25 µm)3, limited by the size of the samples, but sufficient to resolve the vascular system. Experiments confirmed that sufficient perfusion of the vessels with the dyes could be achieved, and the different dyes could be clearly discerned in the reconstructed volumes without causing artifacts allowing to clearly identify features in the soft tissue. Further, the findings were confirmed by histology.Keywords

Shunt-type plexiform lesions identified in the Sugen5416/Hypoxia rat model of pulmonary arterial hypertension using SPµCT

We recently described four distinct types of plexiform lesions in human idiopathic and familial pulmonary arterial hypertension (PAH) [1], visualising the three-dimensional lesion structure using synchrotron-based phase-contrast micro-CT (SPµCT). Two types, 1 and 2, are shunt-type lesions that connect pulmonary arteries to the bronchial circulation: type 1 to the vasa vasorum, and type 2 to peribronchial vessels. Type 3 lesions are found peripherally in the lung as spherical structures abruptly terminating the distal pulmonary artery/arteriole, and type 4 are characterised by recanalization of an occluded artery/arteriole. Our observation of type 1 and type 2 lesions in PAH supports previous work which demonstrated intrapulmonary bronchopulmonary anastomoses (IBAs) connected to plexiform lesions in human PAH, suggesting that shunting of blood can occur within lesions in the setting of supra-systemic pulmonary arterial pressure [2]. Further hemodynamic studies of distinct subtypes of plexiform lesions have been hampered by the lack of available animal models with plexiform lesions representative of the full range of lesion types found in human disease. Plexiform lesions have previously been described in the Sugen5416/Hypoxia rat model of pulmonary hypertension when time until sacrifice following hypoxia is extended to 13–14 weeks. Initially plexiform lesions were identified within the lumen as well as outside the vessel as aneurysm-like lesions [3], and recently the latter type was shown to form in supernumerary arteries [4]. However, neither study observed plexiform lesions communicating with the bronchial circulation, possibly because of methodological limitations of the histological analysis

Synchrotron-based phase-contrast micro-CT as a tool for understanding pulmonary vascular pathobiology and the 3-D microanatomy of alveolar capillary dysplasia

This study aimed to explore the value of synchrotron-based phase-contrast microcomputed tomography (micro-CT) in pulmonary vascular pathobiology. The microanatomy of the lung is complex with intricate branching patterns. Tissue sections are therefore difficult to interpret. Recruited intrapulmonary bronchopulmonary anastomoses (IBAs) have been described in several forms of pulmonary hypertension, including alveolar capillary dysplasia with misaligned pulmonary veins (ACD/MPV). Here, we examine paraffin-embedded tissue using this nondestructive method for high-resolution three-dimensional imaging. Blocks of healthy and ACD/MPV lung tissue were used. Pulmonary and bronchial arteries in the ACD/MPV block had been preinjected with dye. One section per block was stained, and areas of interest were marked to allow precise beam-alignment during image acquisition at the X02DA TOMCAT beamline (Swiss Light Source). A ×4 magnifying objective coupled to a 20-µm thick scintillating material and a sCMOS detector yielded the best trade-off between spatial resolution and field-of-view. A phase retrieval algorithm was applied and virtual tomographic slices and video clips of the imaged volumes were produced. Dye injections generated a distinct attenuation difference between vessels and surrounding tissue, facilitating segmentation and three-dimensional rendering. Histology and immunohistochemistry post-imaging offered complementary information. IBAs were confirmed in ACD/MPV, and the MPVs were positioned like bronchial veins/venules. We demonstrate the advantages of using synchrotron-based phase-contrast micro-CT for three-dimensional characterization of pulmonary microvascular anatomy in paraffin-embedded tissue. Vascular dye injections add additional value. We confirm intrapulmonary shunting in ACD/MPV and provide support for the hypothesis that MPVs are dilated bronchial veins/venules

Distinct types of plexiform lesions identified by synchrotron-based phase-contrast micro-CT

In pulmonary arterial hypertension, plexiform lesions are associated with severe arterial obstruction and right ventricular failure. Exploring their structure and position is crucial for understanding the interplay between hemodynamics and vascular remodeling. The aim of this research was to use synchrotron-based phase-contrast micro-CT to study the three-dimensional structure of plexiform lesions. Archived paraffin-embedded tissue samples from 14 patients with pulmonary arterial hypertension (13 idiopathic, 1 with known BMPR2-mutation) were imaged. Clinical data showed high-median PVR (12.5 WU) and mPAP (68 mmHg). Vascular lesions with more than 1 lumen were defined as plexiform. Prior radiopaque dye injection in some samples facilitated 3-D rendering. Four distinct types of plexiform lesions were identified: 1) localized within or derived from monopodial branches (supernumerary arteries), often with a connection to the vasa vasorum; 2) localized between pulmonary arteries and larger airways as a tortuous transformation of intrapulmonary bronchopulmonary anastomoses; 3) as spherical structures at unexpected abrupt ends of distal pulmonary arteries; and 4) as occluded pulmonary arteries with recanalization. By appearance and localization, types 1–2 potentially relieve pressure via the bronchial circulation, as pulmonary arteries in these patients were almost invariably occluded distally. In addition, types 1–3 were often surrounded by dilated thin-walled vessels, often connected to pulmonary veins, peribronchial vessels, or the vasa vasorum. Collaterals, bypassing completely occluded pulmonary arteries, were also observed to originate within plexiform lesions. In conclusion, synchrotron-based imaging revealed significant plexiform lesion heterogeneity, resulting in a novel classification. The four types likely have different effects on hemodynamics and disease progression