Altered blood gas tensions of oxygen and carbon dioxide confound coronary reactivity to apnea

Purpose: Arterial blood gases change frequently during anesthesia and intensive care. Apnea can occur during diagnostic exams and airway and surgical interventions. While the impact of blood gas levels on coronary blood flow is established, their confounding effect on coronary vasoreactivity in response to an apneic stimulus, especially in coronary artery disease, is not known. Methods: Six anesthetized control swine and eleven swine with coronary artery stenosis were examined. Nine different blood gas levels from a combination of arterial partial pressure of oxygen (70, 100, and 300 mmHg) and carbon dioxide (30, 40, and 50 mmHg) were targeted. Apnea was induced by halting controlled positive pressure ventilation for 3–30s, while the left descending coronary artery flow was measured and reported relative to apnea duration, and at the adjusted mean (12s). Results: At normoxemic-normocapnic blood gas levels, apnea increased coronary blood flow in proportion to the duration of apnea in the control (r = 0.533, p < 0.001) and stenosed groups (r = 0.566, p < 0.001). This culminated in a 42% (95% CI: 27–58) increase in controls (p < 0.001) and, to a lesser extent, 27% (15–40) in the presence of coronary artery stenosis (p < 0.001). Vasoreactivity was augmented by mild-hypoxemic levels [81% (65–97), and 66% (53–79) increase in flow respectively, p < 0.001 vs. normoxemia], but markedly reduced during hyperoxia (7.5% (−8.2–23) and 0.3% (−12–13), respectively, p < 0.001 vs. normoxemia). Conclusion: Alterations of blood oxygen and carbon dioxide affect coronary vascular reactivity induced by apnea in swine, which was attenuated further in the presence of coronary stenosis. Especially hyperoxia significantly reduces coronary blood flow and blunts coronary vascular reactivity

Call to action for global access to and harmonization of quality information of individual earth science datasets

Knowledge about the quality of data and metadata is important to support informed decisions on the (re)use of individual datasets and is an essential part of the ecosystem that supports open science. Quality assessments reflect the reliability and usability of data. They need to be consistently curated, fully traceable, and adequately documented, as these are crucial for sound decision- and policy-making efforts that rely on data. Quality assessments also need to be consistently represented and readily integrated across systems and tools to allow for improved sharing of information on quality at the dataset level for individual quality attribute or dimension. Although the need for assessing the quality of data and associated information is well recognized, methodologies for an evaluation framework and presentation of resultant quality information to end users may not have been comprehensively addressed within and across disciplines. Global interdisciplinary domain experts have come together to systematically explore needs, challenges and impacts of consistently curating and representing quality information through the entire lifecycle of a dataset. This paper describes the findings of that effort, argues the importance of sharing dataset quality information, calls for community action to develop practical guidelines, and outlines community recommendations for developing such guidelines. Practical guidelines will allow for global access to and harmonization of quality information at the level of individual Earth science datasets, which in turn will support open science

Call to action for global access to and harmonization of quality information of individual earth science datasets

Knowledge about the quality of data and metadata is important to support informed decisions on the (re)use of individual datasets and is an essential part of the ecosystem that supports open science. Quality assessments reflect the reliability and usability of data. They need to be consistently curated, fully traceable, and adequately documented, as these are crucial for sound decision-and policy-making efforts that rely on data. Quality assessments also need to be consistently represented and readily integrated across systems and tools to allow for improved sharing of information on quality at the dataset level for individual quality attribute or dimension. Although the need for assessing the quality of data and associated information is well recognized, methodologies for an evaluation framework and presentation of resultant quality information to end users may not have been comprehensively addressed within and across disciplines. Global interdisciplinary domain experts have come together to systematically explore needs, challenges and impacts of consistently curating and representing quality information through the entire lifecycle of a dataset. This paper describes the findings of that effort, argues the importance of sharing dataset quality information, calls for community action to develop practical guidelines, and outlines community recommendations for developing such guidelines. Practical guidelines will allow for global access to and harmonization of quality information at the level of individual Earth science datasets, which in turn will support open science

Thalamic Nuclei Localization Using fMRI for Image-Guided Thalamotomy in Movement Disorders

Thalamotomy and deep brain stimulation (DBS) are important surgical options for patients with tremor-dominant movement disorders. They have provided significant improvements to those with Parkinson’s disease (PD), essential tremor (ET), and dystonic tremor (DT) in their daily quality of life. Both neurosurgery techniques require presurgical imaging to localize targets for electrode placement. The thalamus is a common target for patients with uncontrollable tremor. It is made up of multiple, irregularly shaped nuclei with vague and almost indistinguishable topographies. Improving the localization of these nuclei prior to electrode implantation can potentially reduce surgery times and increase success rates. The use of magnetic resonance imaging (MRI) allows us to study soft tissue structures, such as the brain, noninvasively, with high resolution, and without using ionizing radiation. More recently, the functional activity and connections within the brain can be visualized using MRI sequences that detect signals highly correlated with neuronal activity, a technique called functional MRI (fMRI). In this thesis we aimed to localize specific thalamic nuclei using fMRI, by looking at task-based activations (TB-fMRI) and functional connections in the resting state (RS-fMRI), between the thalamus and the sensory and motor cortices in ET and tremor-dominant PD patients, as well as in healthy controls. Results showed that TB-fMRI and RS-fMRI each localized the motor regions of the thalamus to >10mm from expected motor thalamus locations obtained from surgical lesion locations and literature reported locations. There were no differences in localized motor thalamus locations between groups using either fMRI technique. However, the motor thalamus was more distinctly separated from the sensory thalamus using TB-fMRI. This may ultimately result in a more accurate thalamic mapping process prior to thalamic lesioning or DBS electrode implantation, shorten resulting surgical times and improve overall surgical outcome

Hyperoxia Exacerbates Myocardial Ischemia in the Presence of Acute Coronary Artery Stenosis in Swine.

BACKGROUND Current guidelines limit the use of high oxygen tension after return of spontaneous circulation after cardiac arrest, focusing on neurological outcome and mortality. Little is known about the impact of hyperoxia on the ischemic heart. Oxygen is frequently administered and is generally expected to be beneficial. This study seeks to assess the effects of hyperoxia on myocardia oxygenation in the presence of severe coronary artery stenosis in swine. METHODS AND RESULTS In 22 healthy pigs, we surgically attached a magnetic resonance compatible flow probe to the left anterior descending coronary artery (LAD). In 11 pigs, a hydraulic occluder was inflated distal to the flow probe. After increasing PaO2 to >300 mm Hg, LAD flow decreased in all animals. In 8 stenosed animals with a mean fractional flow reserve of 0.64±0.02, hyperoxia resulted in a significant decrease of myocardial signal intensity in oxygenation-sensitive cardiovascular magnetic resonance images of the midapical segments of the LAD territory. This was not seen in remote myocardium or in the other 8 healthy animals. The decreased signal intensity was accompanied by a decrease in circumferential strain in the same segments. Furthermore, ejection fraction, cardiac output, and oxygen extraction ratio declined in these animals. Changing PaCO2 levels did not have a significant effect on any of the parameters; however, hypercapnia seemed to nonsignificantly attenuate the hyperoxia-induced changes. CONCLUSIONS Ventilation-induced hyperoxia may decrease myocardial oxygenation and lead to ischemia in myocardium subject to severe coronary artery stenosis

Breathing Maneuvers as a Vasoactive Stimulus for Detecting Inducible Myocardial Ischemia - An Experimental Cardiovascular Magnetic Resonance Study.

BACKGROUND Breathing maneuvers can elicit a similar vascular response as vasodilatory agents like adenosine; yet, their potential diagnostic utility in the presence of coronary artery stenosis is unknown. The objective of the study is to investigate if breathing maneuvers can non-invasively detect inducible ischemia in an experimental animal model when the myocardium is imaged with oxygenation-sensitive cardiovascular magnetic resonance (OS-CMR). METHODS AND FINDINGS In 11 anesthetised swine with experimentally induced significant stenosis (fractional flow reserve <0.75) of the left anterior descending coronary artery (LAD) and 9 control animals, OS-CMR at 3T was performed during two different breathing maneuvers, a long breath-hold; and a combined maneuver of 60s of hyperventilation followed by a long breath-hold. The resulting change of myocardial oxygenation was compared to the invasive measurements of coronary blood flow, blood gases, and oxygen extraction. In control animals, all breathing maneuvers could significantly alter coronary blood flow as hyperventilation decreased coronary blood flow by 34±23%. A long breath-hold alone led to an increase of 97±88%, while the increase was 346±327% (p<0.001), when the long breath-hold was performed after hyperventilation. In stenosis animals, the coronary blood flow response was attenuated after both hyperventilation and the following breath-hold. This was matched by the observed oxygenation response as breath-holds following hyperventilation consistently yielded a significant difference in the signal of the MRI images between the perfusion territory of the stenosis LAD and remote myocardium. There was no difference between the coronary territories during the other breathing maneuvers or in the control group at any point. CONCLUSION In an experimental animal model, the response to a combined breathing maneuver of hyperventilation with subsequent breath-holding is blunted in myocardium subject to significant coronary artery stenosis. This maneuver may allow for detecting severe coronary artery stenosis and have a significant clinical potential as a non-pharmacological method for diagnostic testing in patients with suspected coronary artery disease

Development of an evidence-based educational resource in oncology: ‘Living safely with bone metastases’

Objective: To create an evidence-based patient education resource to better support cancer patients with bone metastases in carrying out safe movements during activities of daily living, to maintain their bone health and reduce the risk of fractures. Methods: A quality improvement project was conducted in three phases: Development of the Resource, Preliminary Feedback and Revision, and French Canadian Translation. Results: The educational resource Living Safely with Bone Metastases focuses on safe movement, activities of daily living, and exercise, organized within the sections Move with care, Stay safe in different environments and Follow an exercise program prescribed by a physiotherapist. Translation yielded a Canadian French version Vivre en toute sécurité avec des métastases osseuses. Conclusion: Living Safely with Bone Metastases is an accessible online and paper resource for patients and healthcare professionals, in order to promote ongoing disease management of individuals with bone metastases. Innovation: Cancer patients with bone metastases are at high risk of pathological fractures however resources on fracture prevention are lacking. Living Safely with Bone Metastases is an innovative health education resource that fills an important gap in oncology practice and has the potential to reduce the occurrence of fractures

Myocardial oxygenation response curve during the HVBH.

<p>Signal intensity increases globally during the HVBH in control animals (A), yet the animals with a stenosis (B) show a significant decrease in the LAD territory (blue), while the remote region (green) remains above baseline with a similar characteristic of the control animals.</p