In JoVE (1)

Other Publications (31)

Articles by Sarah Power in JoVE

 JoVE Behavior

Using Fiberless, Wearable fNIRS to Monitor Brain Activity in Real-world Cognitive Tasks

1Department of Medical Physics and Biomedical Engineering, Malet Place Engineering Building, University College London, 2Infrared Imaging Lab, Institute for Advanced Biomedical Technology (ITAB), Department of Neuroscience, Imaging and Clinical Sciences, University of Chieti-Pescara, 3Institute of Cognitive Neuroscience, Alexandra House, University College London


JoVE 53336

Other articles by Sarah Power on PubMed

Evaluation of Acridine in Nafion As a Fluorescence-lifetime-based PH Sensor

Applied Spectroscopy. Jan, 2003  |  Pubmed ID: 14610939

We report a novel fluorescence-lifetime-based pH sensing method that utilizes acridine incorporated into Nafion (AcNaf) as the fluorescent indicator. The AcNaf sensor is excited using a 380 nm light emitting diode (LED) and the fluorescence lifetimes are measured at 450 and 500 nm. The fluorescence behavior of acridine as a function of pH in aqueous phosphate buffers and incorporated into the Nafion membrane has been investigated. The results show that incorporating acridine into Nafion changes the apparent ground-state pKa from -5.45 to -9, while the apparent excited-state pKa* is only slightly changed (approximately 9.4 in 0.1 M phosphate buffer). The AcNaf film shows a good pH response with a change in average lifetime of approximately 19 ns (at an emission wavelength of 450 nm) over the pH 8 to 10 range. We also show that excited-state protonation does not occur in the AcNaf sensor film and that chloride quenching cannot occur because of the permselective nature of Nafion. We also discuss how the unique structure of Nafion affects the fluorescence behavior of acridine at various pH values and examine the impact of buffer concentration on apparent pKa and pH sensing ability.

Classification of Prefrontal Activity Due to Mental Arithmetic and Music Imagery Using Hidden Markov Models and Frequency Domain Near-infrared Spectroscopy

Journal of Neural Engineering. Apr, 2010  |  Pubmed ID: 20168001

Near-infrared spectroscopy (NIRS) has recently been investigated as a non-invasive brain-computer interface (BCI). In particular, previous research has shown that NIRS signals recorded from the motor cortex during left- and right-hand imagery can be distinguished, providing a basis for a two-choice NIRS-BCI. In this study, we investigated the feasibility of an alternative two-choice NIRS-BCI paradigm based on the classification of prefrontal activity due to two cognitive tasks, specifically mental arithmetic and music imagery. Deploying a dual-wavelength frequency domain near-infrared spectrometer, we interrogated nine sites around the frontopolar locations (International 10-20 System) while ten able-bodied adults performed mental arithmetic and music imagery within a synchronous shape-matching paradigm. With the 18 filtered AC signals, we created task- and subject-specific maximum likelihood classifiers using hidden Markov models. Mental arithmetic and music imagery were classified with an average accuracy of 77.2% +/- 7.0 across participants, with all participants significantly exceeding chance accuracies. The results suggest the potential of a two-choice NIRS-BCI based on cognitive rather than motor tasks.

A Cardiorespiratory Classifier of Voluntary and Involuntary Electrodermal Activity

Biomedical Engineering Online. 2010  |  Pubmed ID: 20184746

Electrodermal reactions (EDRs) can be attributed to many origins, including spontaneous fluctuations of electrodermal activity (EDA) and stimuli such as deep inspirations, voluntary mental activity and startling events. In fields that use EDA as a measure of psychophysiological state, the fact that EDRs may be elicited from many different stimuli is often ignored. This study attempts to classify observed EDRs as voluntary (i.e., generated from intentional respiratory or mental activity) or involuntary (i.e., generated from startling events or spontaneous electrodermal fluctuations).

On the Use of Peripheral Autonomic Signals for Binary Control of Body-machine Interfaces

Physiological Measurement. Nov, 2010  |  Pubmed ID: 20834114

In this work, the potential of using peripheral autonomic (PA) responses as control signals for body-machine interfaces that require no physical movement was investigated. Electrodermal activity, skin temperature, heart rate and respiration rate were collected from six participants and hidden Markov models (HMMs) were used to automatically detect when a subject was performing music imagery as opposed to being at rest. Experiments were performed under controlled silent conditions as well as in the presence of continuous and startle (e.g. door slamming) ambient noise. By developing subject-specific HMMs, music imagery was detected under silent conditions with the average sensitivity and specificity of 94.2% and 93.3%, respectively. In the presence of startle noise stimuli, the system sensitivity and specificity levels of 78.8% and 80.2% were attained, respectively. In environments corrupted by continuous ambient and startle noise, the system specificity further decreased to 75.9%. To improve the system robustness against environmental noise, a startle noise detection and compensation strategy were proposed. Once in place, performance levels were shown to be comparable to those observed in silence. The obtained results suggest that PA signals, combined with HMMs, can be useful tools for the development of body-machine interfaces that allow individuals with severe motor impairments to communicate and/or to interact with their environment.

Nanotechnology and Its Relationship to Interventional Radiology. Part II: Drug Delivery, Thermotherapy, and Vascular Intervention

Cardiovascular and Interventional Radiology. Aug, 2011  |  Pubmed ID: 20845040

Nanotechnology can be defined as the design, creation, and manipulation of structures on the nanometer scale. This two-part review is intended to acquaint the interventionalist with the field of nanotechnology, and provide an overview of potential applications, while highlighting advances relevant to interventional radiology. Part 2 of the article concentrates on drug delivery, thermotherapy, and vascular intervention. In oncology, advances in drug delivery allow for improved efficacy, decreased toxicity, and greater potential for targeted therapy. Magnetic nanoparticles show potential for use in thermotherapy treatments of various tumours, and the effectiveness of radiofrequency ablation can be enhanced with nanoparticle chemotherapy agents. In vascular intervention, much work is focused on prevention of restenosis through developments in stent technology and systems for localised drug delivery to vessel walls. Further areas of interest include applications for thrombolysis and haemostasis.

Nanotechnology and Its Relationship to Interventional Radiology. Part I: Imaging

Cardiovascular and Interventional Radiology. Apr, 2011  |  Pubmed ID: 20845041

Nanotechnology refers to the design, creation, and manipulation of structures on the nanometer scale. Interventional radiology stands to benefit greatly from advances in nanotechnology because much of the ongoing research is focused toward novel methods of imaging and delivery of therapy through minimally invasive means. Through the development of new techniques and therapies, nanotechnology has the potential to broaden the horizon of interventional radiology and ensure its continued success. This two-part review is intended to acquaint the interventionalist with the field of nanotechnology, and provide an overview of potential applications, while highlighting advances relevant to interventional radiology. Part I of the article deals with an introduction to some of the basic concepts of nanotechnology and outlines some of the potential imaging applications, concentrating mainly on advances in oncological and vascular imaging.

Taking NIRS-BCIs Outside the Lab: Towards Achieving Robustness Against Environment Noise

IEEE Transactions on Neural Systems and Rehabilitation Engineering : a Publication of the IEEE Engineering in Medicine and Biology Society. Apr, 2011  |  Pubmed ID: 20876031

This paper reported initial findings on the effects of environmental noise and auditory distractions on the performance of mental state classification based on near-infrared spectroscopy (NIRS) signals recorded from the prefrontal cortex. Characterization of the performance losses due to environmental factors could provide useful information for the future development of NIRS-based brain-computer interfaces that can be taken beyond controlled laboratory settings and into everyday environments. Experiments with a hidden Markov model-based classifier showed that while significant performance could be attained in silent conditions, only chance levels of sensitivity and specificity were obtained in noisy environments. In order to achieve robustness against environment noise, two strategies were proposed and evaluated. First, physiological responses harnessed from the autonomic nervous system were used as complementary information to NIRS signals. More specifically, four physiological signals (electrodermal activity, skin temperature, blood volume pulse, and respiration effort) were collected in synchrony with the NIRS signals as the user sat at rest and/or performed music imagery tasks. Second, an acoustic monitoring technique was proposed and used to detect startle noise events, as both the prefrontal cortex and ANS are known to involuntarily respond to auditory startle stimuli. Experiments with eight participants showed that with a startle noise compensation strategy in place, performance comparable to that observed in silent conditions could be recovered with the hybrid ANS-NIRS system.

Towards a System-paced Near-infrared Spectroscopy Brain-computer Interface: Differentiating Prefrontal Activity Due to Mental Arithmetic and Mental Singing from the No-control State

Journal of Neural Engineering. Dec, 2011  |  Pubmed ID: 21975364

Near-infrared spectroscopy (NIRS) has recently been investigated as a non-invasive brain-computer interface (BCI) for individuals with severe motor impairments. For the most part, previous research has investigated the development of NIRS-BCIs operating under synchronous control paradigms, which require the user to exert conscious control over their mental activity whenever the system is vigilant. Though functional, this is mentally demanding and an unnatural way to communicate. An attractive alternative to the synchronous control paradigm is system-paced control, in which users are required to consciously modify their brain activity only when they wish to affect the BCI output, and can remain in a more natural, 'no-control' state at all other times. In this study, we investigated the feasibility of a system-paced NIRS-BCI with one intentional control (IC) state corresponding to the performance of either mental arithmetic or mental singing. In particular, this involved determining if these tasks could be distinguished, individually, from the unconstrained 'no-control' state. Deploying a dual-wavelength frequency domain near-infrared spectrometer, we interrogated nine sites around the frontopolar locations (International 10-20 System) while eight able-bodied adults performed mental arithmetic and mental singing to answer multiple-choice questions within a system-paced paradigm. With a linear classifier trained on a six-dimensional feature set, an overall classification accuracy of 71.2% across participants was achieved for the mental arithmetic versus no-control classification problem. While the mental singing versus no-control classification was less successful across participants (62.7% on average), four participants did attain accuracies well in excess of chance, three of which were above 70%. Analyses were performed offline. Collectively, these results are encouraging, and demonstrate the potential of a system-paced NIRS-BCI with one IC state corresponding to either mental arithmetic or mental singing.

Thermal Imaging of the Periorbital Regions During the Presentation of an Auditory Startle Stimulus

PloS One. 2011  |  Pubmed ID: 22073302

Infrared thermal imaging of the inner canthi of the periorbital regions of the face can potentially serve as an input signal modality for an alternative access system for individuals with conditions that preclude speech or voluntary movement, such as total locked-in syndrome. However, it is unknown if the temperature of these regions is affected by the human startle response, as changes in the facial temperature of the periorbital regions manifested during the startle response could generate false positives in a thermography-based access system. This study presents an examination of the temperature characteristics of the periorbital regions of 11 able-bodied adult participants before and after a 102 dB auditory startle stimulus. The results indicate that the startle response has no substantial effect on the mean temperature of the periorbital regions. This indicates that thermography-based access solutions would be insensitive to startle reactions in their user, an important advantage over other modalities being considered in the context of access solutions for individuals with a severe motor disability.

Classification of Activity Engagement in Individuals with Severe Physical Disabilities Using Signals of the Peripheral Nervous System

PloS One. 2012  |  Pubmed ID: 22363432

Communication barriers often result in exclusion of children and youth with disabilities from activities and social settings that are essential to their psychosocial development. In particular, difficulties in describing their experiences of activities and social settings hinder our understanding of the factors that promote inclusion and participation of this group of individuals. To address this specific communication challenge, we examined the feasibility of developing a language-free measure of experience in youth with severe physical disabilities. To do this, we used the activity of the peripheral nervous system to detect patterns of psychological arousal associated with activities requiring different patterns of cognitive/affective and interpersonal involvement (activity engagement). We demonstrated that these signals can differentiate among patterns of arousal associated with these activities with high accuracy (two levels: 81%, three levels: 74%). These results demonstrate the potential for development of a real-time, motor- and language-free measure for describing the experiences of children and youth with disabilities.

Automatic Single-trial Discrimination of Mental Arithmetic, Mental Singing and the No-control State from Prefrontal Activity: Toward a Three-state NIRS-BCI

BMC Research Notes. 2012  |  Pubmed ID: 22414111

Near-infrared spectroscopy (NIRS) is an optical imaging technology that has recently been investigated for use in a safe, non-invasive brain-computer interface (BCI) for individuals with severe motor impairments. To date, most NIRS-BCI studies have attempted to discriminate two mental states (e.g., a mental task and rest), which could potentially lead to a two-choice BCI system. In this study, we attempted to automatically differentiate three mental states - specifically, intentional activity due to 1) a mental arithmetic (MA) task and 2) a mental singing (MS) task, and 3) an unconstrained, "no-control (NC)" state - to investigate the feasibility of a three-choice system-paced NIRS-BCI.

Automatic Detection of a Prefrontal Cortical Response to Emotionally Rated Music Using Multi-channel Near-infrared Spectroscopy

Journal of Neural Engineering. Apr, 2012  |  Pubmed ID: 22419117

Emotional responses can be induced by external sensory stimuli. For severely disabled nonverbal individuals who have no means of communication, the decoding of emotion may offer insight into an individual's state of mind and his/her response to events taking place in the surrounding environment. Near-infrared spectroscopy (NIRS) provides an opportunity for bed-side monitoring of emotions via measurement of hemodynamic activity in the prefrontal cortex, a brain region known to be involved in emotion processing. In this paper, prefrontal cortex activity of ten able-bodied participants was monitored using NIRS as they listened to 78 music excerpts with different emotional content and a control acoustic stimuli consisting of the Brown noise. The participants rated their emotional state after listening to each excerpt along the dimensions of valence (positive versus negative) and arousal (intense versus neutral). These ratings were used to label the NIRS trial data. Using a linear discriminant analysis-based classifier and a two-dimensional time-domain feature set, trials with positive and negative emotions were discriminated with an average accuracy of 71.94% ± 8.19%. Trials with audible Brown noise representing a neutral response were differentiated from high arousal trials with an average accuracy of 71.93% ± 9.09% using a two-dimensional feature set. In nine out of the ten participants, response to the neutral Brown noise was differentiated from high arousal trials with accuracies exceeding chance level, and positive versus negative emotional differentiation accuracies exceeded the chance level in seven out of the ten participants. These results illustrate that NIRS recordings of the prefrontal cortex during presentation of music with emotional content can be automatically decoded in terms of both valence and arousal encouraging future investigation of NIRS-based emotion detection in individuals with severe disabilities.

Intersession Consistency of Single-trial Classification of the Prefrontal Response to Mental Arithmetic and the No-control State by NIRS

PloS One. 2012  |  Pubmed ID: 22844390

Near-infrared spectroscopy (NIRS) has been recently investigated for use in noninvasive brain-computer interface (BCI) technologies. Previous studies have demonstrated the ability to classify patterns of neural activation associated with different mental tasks (e.g., mental arithmetic) using NIRS signals. Though these studies represent an important step towards the realization of an NIRS-BCI, there is a paucity of literature regarding the consistency of these responses, and the ability to classify them on a single-trial basis, over multiple sessions. This is important when moving out of an experimental context toward a practical system, where performance must be maintained over longer periods. When considering response consistency across sessions, two questions arise: 1) can the hemodynamic response to the activation task be distinguished from a baseline (or other task) condition, consistently across sessions, and if so, 2) are the spatiotemporal characteristics of the response which best distinguish it from the baseline (or other task) condition consistent across sessions. The answers will have implications for the viability of an NIRS-BCI system, and the design strategies (especially in terms of classifier training protocols) adopted. In this study, we investigated the consistency of classification of a mental arithmetic task and a no-control condition over five experimental sessions. Mixed model linear regression on intrasession classification accuracies indicate that the task and baseline states remain differentiable across multiple sessions, with no significant decrease in accuracy (p = 0.67). Intersession analysis, however, revealed inconsistencies in spatiotemporal response characteristics. Based on these results, we investigated several different practical classifier training protocols, including scenarios in which the training and test data come from 1) different sessions, 2) the same session, and 3) a combination of both. Results indicate that when selecting optimal classifier training protocols for NIRS-BCI, a compromise between accuracy and convenience (e.g., in terms of duration/frequency of training data collection) must be considered.

Insertion of Balloon Retained Gastrostomy Buttons: a 5-year Retrospective Review of 260 Patients

Cardiovascular and Interventional Radiology. Apr, 2013  |  Pubmed ID: 22869044

Radiologically inserted gastrostomy (RIG) is an established way of maintaining enteral nutrition in patients who cannot maintain nutrition orally. The purpose of this study was to evaluate the safety and efficacy of primary placement of a wide bore button gastrostomy in a large, varied patient population through retrospective review.

Automatic Single-trial Classification of Prefrontal Hemodynamic Activity in an Individual with Duchenne Muscular Dystrophy

Developmental Neurorehabilitation. 2013  |  Pubmed ID: 23030232

Brain-computer interfaces (BCIs) allow users to control external devices via brain activity alone, circumventing the somatic nervous system and the need for overt movement. Essential to BCI development is the ability to accurately detect and classify patterns of activation associated with different mental tasks. Here, we investigate the ability to automatically distinguish a mental arithmetic (MA) task from a natural baseline state in an individual with Duchenne muscular dystrophy (DMD) using signals acquired via multichannel near-infrared spectroscopy (NIRS). Using dual-wavelength NIRS, we interrogated nine sites around the frontopolar locations while the individual performed MA to answer multiple-choice questions within a system-paced paradigm. An encouraging overall classification accuracy of 71.1% was obtained, which is comparable to the average accuracy we previously reported for healthy individuals performing the same task. This result demonstrates the potential of NIRS-BCI based on task-induced prefrontal activity for use by individuals with DMD.

Dynamic Topographical Pattern Classification of Multichannel Prefrontal NIRS Signals

Journal of Neural Engineering. Aug, 2013  |  Pubmed ID: 23867792

Near-infrared spectroscopy (NIRS) is an optical imaging technique that has recently been considered for brain-computer interface (BCI) applications. To date, NIRS-BCI studies have primarily made use of temporal features of brain activity, derived from the time-course of optical signals measured from discrete locations, to differentiate mental states. However, functional brain imaging studies have indicated that the spatial distribution of haemodynamic activity is also rich in information. Thus, the progression of a response over both time and space may be valuable to brain state classification. In this paper, we investigate the implication of including spatiotemporal features in the single-trial classification of haemodynamic events for a two-class problem by exploiting this information from dynamic NIR topograms.

The Protocolised Management in Sepsis (ProMISe) Trial Statistical Analysis Plan

Critical Care and Resuscitation : Journal of the Australasian Academy of Critical Care Medicine. Dec, 2013  |  Pubmed ID: 24289513

The Protocolised Management in Sepsis (ProMISe) trial is an open, multicentre, randomised controlled trial (RCT) of the clinical effectiveness and cost-effectiveness of early, goal directed, protocolised resuscitation compared with usual resuscitation for patients presenting to emergency departments (EDs) in the United Kingdom with early signs of severe sepsis or septic shock. The rationale for the ProMISe trial derives from a single-centre United States RCT that reported a reduction in hospital mortality from 46.5% to 30.5%.

Incidence and Outcome of In-hospital Cardiac Arrest in the United Kingdom National Cardiac Arrest Audit

Resuscitation. Aug, 2014  |  Pubmed ID: 24746785

To report the incidence, characteristics and outcome of adult in-hospital cardiac arrest in the United Kingdom (UK) National Cardiac Arrest Audit database.

Vessel Wall Magnetic Resonance Imaging in Acute Ischemic Stroke: Effects of Embolism and Mechanical Thrombectomy on the Arterial Wall

Stroke; a Journal of Cerebral Circulation. Aug, 2014  |  Pubmed ID: 24964050

The aim of the study was to determine the effects of thromboembolism and mechanical thrombectomy on the vessel wall magnetic resonance imaging (VW-MRI) appearance of the intracranial arterial wall.

Outcome Prediction in Acute Stroke Patients Considered for Endovascular Treatment: a Novel Tool

Interventional Neuroradiology : Journal of Peritherapeutic Neuroradiology, Surgical Procedures and Related Neurosciences. May-Jun, 2014  |  Pubmed ID: 24976094

Functional outcome following emergent intra-arterial thrombectomy is variable and likely reflects the heterogeneous characteristics of acute stroke patients. The aims of our study were (1) to study which pre-treatment variables correlate with functional outcome and (2) to devise a tool which would reliably predict outcome. Prospective data of patients treated with intra-arterial mechanical thrombectomy in our institution between 2010 and 2012 were collected. A preliminary univariate analysis of baseline variables was performed and data outliers were identified by constructing scatter and box plots. Systematic bivariate analysis was then carried out using a linear regression model and the individual contributing weights of the variables to outcome calculated. The B and constant values from the regression were used to construct a predictive formula. Fifty-seven patients, 35 males (61.4%) and 22 females (38.6%) with a mean age of 62.3 years (range 26-87) were included in the cohort. Statistical correlations of baseline variables and functional outcome showed that age, National Institutes of Health Stroke Scale at presentation and CT leptomeningeal collaterals were strongly correlated (p<0.01), and were later included in the linear regression model. A tool was devised from the regression formula combining weighted inputs of the three variables. Regression statistics and residual analysis were then performed to assess the accuracy and reliability of the proposed tool. The proposed tool is easy to use and reliably predicts functional outcome prior to endovascular therapy. It may help clinical decision-making in the acute setting and offers 'tailor-made' outcome expectations.

Two Cases of Intraventricular Hemorrhage in Young Patients

Brain Pathology (Zurich, Switzerland). Jul, 2014  |  Pubmed ID: 25083535

Why Try to Predict ICU Outcomes?

Current Opinion in Critical Care. Oct, 2014  |  Pubmed ID: 25159474

To describe why the prediction of ICU outcomes is essential to underpin critical care quality improvement programmes.

Accessible or Inaccessible? Diagnostic Efficacy of CT-guided Core Biopsies of Head and Neck Masses

Cardiovascular and Interventional Radiology. Apr, 2015  |  Pubmed ID: 24938903

Tissue sampling of lesions in the head and neck is challenging due to complex regional anatomy and sometimes necessitates open surgical biopsy. However, many patients are poor surgical candidates due to comorbidity. Thus, we evaluated the use of CT guidance for establishing histopathological diagnosis of head and neck masses.

Comparison of Ultrasound-guided and Fluoroscopy-assisted Antegrade Common Femoral Artery Puncture Techniques

Cardiovascular and Interventional Radiology. Jun, 2015  |  Pubmed ID: 25338833

To prospectively compare the procedural time and complication rates of ultrasound-guided and fluoroscopy-assisted antegrade common femoral artery (CFA) puncture techniques.

Natural History and Management of Basilar Trunk Artery Aneurysms

Stroke; a Journal of Cerebral Circulation. Apr, 2015  |  Pubmed ID: 25712945

Basilar trunk aneurysms (BTAs), defined as aneurysms distal to the basilar origin and proximal to the origin of the superior cerebellar artery, are rare and challenging to manage. We describe the natural history and management in a consecutive series of BTAs.

Trial of Early, Goal-directed Resuscitation for Septic Shock

The New England Journal of Medicine. Apr, 2015  |  Pubmed ID: 25776532

Early, goal-directed therapy (EGDT) is recommended in international guidelines for the resuscitation of patients presenting with early septic shock. However, adoption has been limited, and uncertainty about its effectiveness remains.

Value of CT Angiography in Anterior Circulation Large Vessel Occlusive Stroke: Imaging Findings, Pearls, and Pitfalls

European Journal of Radiology. Jul, 2015  |  Pubmed ID: 25956493

Hyperacute stroke imaging is playing an increasingly important role in determining management decisions in acute stroke patients, particularly patients with large vessel occlusive stroke who may benefit from endovascular intervention. CT angiography (CTA) is an important tool in the work-up of the acute stroke patient. It reliably detects large occlusive thrombi in proximal cerebral arteries and is a quick and highly accurate method in identifying candidates for endovascular stroke treatment. In this article we review the imaging findings on CTA in acute large vessel occlusive stroke using a pictorial case based approach. We retrospectively reviewed CTA studies in 48 patients presenting with acute anterior circulation large vessel occlusive stroke who were brought for intra-arterial acute stroke intervention. We discuss and illustrate patterns of proximal intracranial arterial occlusion, collateralization to the occluded territory, as well as reviewing some important pearls, pitfalls and teaching points in CTA assessment of the acute stroke patient. Performed from the level of the aortic arch CTA also gives valuable information regarding the state of other vessels in the acute stroke patient, identifying additional significant vascular stenoses or occlusions, and as we illustrate, can demonstrate other clinically significant findings which may impact on patient management and outcome.

Regional Variation in Critical Care Provision and Outcome After High-risk Surgery

Intensive Care Medicine. Oct, 2015  |  Pubmed ID: 26202040

Evidence of variation in mortality after surgery may indicate preventable postoperative death. We sought to determine if regional differences in outcome were present in surgical patients admitted to critical care in the UK.

Early, Goal-Directed Resuscitation for Septic Shock

The New England Journal of Medicine. Aug, 2015  |  Pubmed ID: 26244314

Alternative Technique for Clot Retrieval: The "tip of the Iceberg" Technique

Interventional Neuroradiology : Journal of Peritherapeutic Neuroradiology, Surgical Procedures and Related Neurosciences. Dec, 2015  |  Pubmed ID: 26472639

We present a variation of the classical technique of stent retriever thrombectomy which we found helpful in two patients presenting with acute stroke. CT angiography in both patients demonstrated thrombus within a middle cerebral artery M2 branch. In both cases the occluded artery was not visualized on DSA and only the proximal tip of the clot could be seen as a filling defect "hanging" into the parent artery reminiscent of a "tip of an iceberg". Rather than selectively catheterizing the occluded branch we placed the stent retriever in the patent parent artery crossing only the tip of the clot. In both cases one pass of the stent retriever was sufficient to retrieve the whole clot by its tip and reopen the occluded branch. We suggest trying this technique whenever the clot is seated in the proximal part of a secondary branch such as an M2 segment of middle cerebral artery. This "tip of the iceberg" technique prevents the need to selectively catheterize the occluded branch which, if difficult, can prolong procedural and ischemic time.

Protocolised Management In Sepsis (ProMISe): a Multicentre Randomised Controlled Trial of the Clinical Effectiveness and Cost-effectiveness of Early, Goal-directed, Protocolised Resuscitation for Emerging Septic Shock

Health Technology Assessment (Winchester, England). Nov, 2015  |  Pubmed ID: 26597979

Early goal-directed therapy (EGDT) is recommended in international guidance for the resuscitation of patients presenting with early septic shock. However, adoption has been limited and uncertainty remains over its clinical effectiveness and cost-effectiveness.

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