All Publications
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Anesthetic Considerations for Liver Transplantation in a Patient with Mitochondrial Neurogastrointestinal Encephalopathy Syndrome
CUREUS
2019; 11 (6)
View details for DOI 10.7759/cureus.5038
View details for Web of Science ID 000475407900007
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Curricular Innovations for Medical Students in Palliative and End-of-Life Care: A Systematic Review and Assessment of Study Quality
JOURNAL OF PALLIATIVE MEDICINE
2015; 18 (4): 338-349
Abstract
Recent focus on palliative and end-of-life care has led medical schools worldwide to enhance their palliative care curricula.The objective of the study was to describe recent curricular innovations in palliative care for medical students, evaluate the quality of studies in the field, and inform future research and curricular design.The authors searched Medline, Scopus, and Educational Resource Information Center (ERIC) for English-language articles published between 2007 and 2013 describing a palliative care curriculum for medical students. Characteristics of the curricula were extracted, and methodological quality was assessed using the Medical Education Research Study Quality Instrument (MERSQI).The sample described 48 curricula in 12 countries. Faculty were usually interdisciplinary. Palliative care topics included patient assessment, communication, pain and symptom management, psychosocial and spiritual needs, bioethics and the law, role in the health care system, interdisciplinary teamwork, and self-care. Thirty-nine articles included quantitative evaluation, with a mean MERSQI score of 9.9 (on a scale of 5 to 18). The domain most likely to receive a high score was data analysis (mean 2.51 out of 3), while the domains most likely to receive low scores were validity of instrument (mean 1.05) and outcomes (mean 1.31).Recent innovations in palliative care education for medical students represent varied settings, learner levels, instructors, educational modalities, and palliative care topics. Future curricula should continue to incorporate interdisciplinary faculty. Studies could be improved by integrating longitudinal curricula and longer-term outcomes; collaborating across institutions; using validated measures; and assessing higher-level outcomes including skills, behaviors, and impact on patient care.
View details for DOI 10.1089/jpm.2014.0270
View details for Web of Science ID 000351274500008
View details for PubMedID 25549065
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Hypothermia Amplifies Somatosensory-evoked Potentials in Uninjured Rats
JOURNAL OF NEUROSURGICAL ANESTHESIOLOGY
2012; 24 (3): 197-202
Abstract
Temperature fluctuations significantly impact neurological injuries in intensive care units. As the benefits of therapeutic hypothermia continue to unfold, many of these discoveries are generated by studies in animal models undergoing experimental procedures under the influence of anesthetics. We studied the effect of induced hypothermia on neural electrophysiological signals of an uninjured brain in a rodent model while under isoflurane. Fourteen rats were divided into 2 groups (n=7 each), on the basis of electrode placement at either frontal-occipital or primary somatosensory cortical locations. Neural signals were recorded during normothermia (T=36.5 to 37.5°C), mild hypothermia (T=32 to 34°C), and hyperthermia (T=38.5 to 39.5°C). The burst-suppression ratio was used to evaluate electroencephalography (EEG), and amplitude-latency analysis was used to assess somatosensory-evoked potentials (SSEPs). Hypothermia was characterized by an increased burst-suppression ratio (mean±SD) of 0.58±0.06 in hypothermia versus 0.16±0.13 in normothermia, P<0.001 in frontal-occipital; and 0.30±0.13 in hypothermia versus 0.04±0.04 in normothermia, P=0.006 in somatosensory. There was potentiation of SSEP (2.89±1.24 times the normothermic baseline in hypothermia, P=0.02) and prolonged peak latency (N10: 10.8±0.4 ms in hypothermia vs. 9.1±0.3 ms in normothermia; P15: 16.2±0.8 ms in hypothermia vs. 13.7±0.6 ms in normothermia; P<0.001), whereas hyperthermia was primarily marked by shorter peak latencies (N10: 8.6±0.2 ms, P15: 12.6±0.4 m; P<0.001). In the absence of brain injury in a rodent model, hypothermia induces significant increase to the SSEP amplitude while increasing SSEP latency. Hypothermia also suppressed EEGs at different regions of the brain by different degrees. The changes to SSEP and EEG are both reversible with subsequent rewarming.
View details for DOI 10.1097/ANA.0b013e31824ac36c
View details for Web of Science ID 000305272400005
View details for PubMedID 22441433
View details for PubMedCentralID PMC3372632
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Study of the origin of short- and long-latency SSEP during recovery from brain ischemia in a rat model
NEUROSCIENCE LETTERS
2010; 485 (3): 157-161
Abstract
Somatosensory evoked potentials (SSEPs) have been established as an electrophysiological tool for the prognostication of neurological outcome in patients with hypoxic-ischemic brain injury. The early and late responses in SSEPs reflect the sequential activation of neural structures along the somatosensory pathway. This study reports that the SSEP can be separated into early (short-latency, SL) and late (long-latency, LL) responses using independent component analysis (ICA), based on the assumption that these components are generated from different neural sources. Moreover, this source separation into the SL and LL components allows analysis of electrophysiological response to brain injury, even when the SSEPs are severely distorted and SL and LL components get mixed. With the help of ICA decomposition and corrected peak estimation, the latency of LL-SSEP is shown to be predictive of long-term neurological outcome. Further, it is shown that the recovery processes of SL- and LL-SSEPs follow different dynamics, with the SL-SSEP restored earlier than LL-SSEP. We predict that the SL- and LL-SSEPs reflect the timing of the progression of evoked response through the thalamocortical pathway and as such respond differently depending upon injury and recovery of the thalamic and cortical regions, respectively.
View details for DOI 10.1016/j.neulet.2010.08.086
View details for Web of Science ID 000284017400004
View details for PubMedID 20816917
View details for PubMedCentralID PMC2997340
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Quantitative assessment of somatosensory-evoked potentials after cardiac arrest in rats: Prognostication of functional outcomes
CRITICAL CARE MEDICINE
2010; 38 (8): 1709-1717
Abstract
High incidence of poor neurologic sequelae after resuscitation from cardiac arrest underscores the need for objective electrophysiological markers for assessment and prognosis. This study aims to develop a novel marker based on somatosensory evoked potentials (SSEPs). Normal SSEPs involve thalamocortical circuits suggested to play a role in arousal. Due to the vulnerability of these circuits to hypoxic-ischemic insults, we hypothesize that quantitative SSEP markers may indicate future neurologic status.Laboratory investigation.University Medical School and Animal Research Facility.: Sixteen adult male Wistar rats.None.SSEPs were recorded during baseline, during the first 4 hrs, and at 24, 48, and 72 hrs postasphyxia from animals subjected to asphyxia-induced cardiac arrest for 7 or 9 mins (n = 8/group). Functional evaluation was performed using the Neurologic Deficit Score (NDS). For quantitative analysis, the phase space representation of the SSEPs-a plot of the signal vs. its slope-was used to compute the phase space area bounded by the waveforms recorded after injury and recovery. Phase space areas during the first 85-190 mins postasphyxia were significantly different between rats with good (72 hr NDS >or=50) and poor (72 hr NDS <50) outcomes (p = .02). Phase space area not only had a high outcome prediction accuracy (80-93%, p < .05) during 85-190 mins postasphyxia but also offered 78% sensitivity to good outcomes without compromising specificity (83-100%). A very early peak of SSEPs that precedes the primary somatosensory response was found to have a modest correlation with the 72 hr NDS subscores for thalamic and brainstem function (p = .066) and not with sensory-motor function (p = .30).Phase space area, a quantitative measure of the entire SSEP morphology, was shown to robustly track neurologic recovery after cardiac arrest. SSEPs are among the most reliable predictors of poor outcome after cardiac arrest; however, phase space area values early after resuscitation can enhance the ability to prognosticate not only poor but also good long-term neurologic outcomes.
View details for DOI 10.1097/CCM.0b013e3181e7dd29
View details for Web of Science ID 000280116500011
View details for PubMedID 20526197
View details for PubMedCentralID PMC3050516
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Evolution of somatosensory evoked potentials after cardiac arrest induced hypoxic-ischemic injury
RESUSCITATION
2010; 81 (7): 893-897
Abstract
We tested the hypothesis that early recovery of cortical SEP would be associated with milder hypoxic-ischemic injury and better outcome after resuscitation from CA.Sixteen adult male Wistar rats were subjected to asphyxial cardiac arrest. Half underwent 7min of asphyxia (Group CA7) and half underwent 9min (Group CA9). Continuous SEPs from median nerve stimulation were recorded from these rats for 4h immediately following CA, and at 24, 48, and 72h. Clinical recovery was evaluated using the Neurologic Deficit Scale.All rats in group CA7 survived to 72h, while only 50% of rats in group CA9 survived to that time. Mean NDS values in the CA7 group at 24, 48, and 72h after CA were significantly higher than those of CA9. The N10 (first negative potential at 10ms) amplitude was significantly lower within 1h after CA in rats that suffered longer CA durations. SEPs were also analyzed by separating the rats into good (NDS>or=50) vs. bad (NDS<50) outcomes at 72h, again showing significant difference in N10 and peak-to-peak amplitudes between the two groups. In addition, a smaller N7 potential was consistently observed to recover earlier in all rats.The diminished recovery of N10 is associated with longer CA times in rats. Higher N10 and peak-to-peak amplitudes during early recovery are associated with better neurologic outcomes. N7, which may represent thalamic activity, recovers much earlier than cortical responses (N10), suggesting failure of thalamocortical conduction during early recovery.
View details for DOI 10.1016/j.resuscitation.2010.03.030
View details for Web of Science ID 000279758500025
View details for PubMedID 20418008
View details for PubMedCentralID PMC2893290
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Characterization of Neurologic Injury using Novel Morphological Analysis of Somatosensory Evoked Potentials
32nd Annual International Conference of the IEEE Engineering-in-Medicine-and-Biology-Society (EMBC 10)
IEEE. 2010: 2798?2801
Abstract
This paper describes an innovative, easy-to-interpret, clinically translatable tool for analysis of Somatosensory Evoked Potentials (SSEPs). Unlike traditional analysis, which involves peak-to-peak amplitude and latency calculation, this method, phase space analysis, analyzes the overall morphology of the SSEP, and includes greater information. The SSEP is plotted in phase space (x-dot vs. x), which leads to an approximately spiral curve. The area swept out by this curve is termed the Phase Space Area (PSA). As PSA calculation involves numerical differentiation, we present a comparison of two different approaches to combat noise amplification: finite-window smoothing, and total variation regularization (TVR) of the numerical derivative. These methods are applied to simulated SSEPs. The efficacy of these methods in performing noise-reduction is assessed and compared with ensemble averaging. While TVR gives a reasonably robust approximation of the derivative, Gaussian smoothing of the derivative offers the best trade-off between the number of signal sweeps required to be averaged, close approximation of the SSEP derivative, and optimal estimation of the PSA. We validate this method by analyzing non-characteristic SSEPs that have indistinguishable peaks as is frequently seen in cases of underlying neurologic injury such as hypoxic-ischemic encephalopathy.
View details for Web of Science ID 000287964003051
View details for PubMedID 21095700
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Discovery of Long-Latency Somatosensory Evoked Potentials as a Marker of Cardiac Arrest Induced Brain Injury
SPRINGER. 2010: 101?4
View details for Web of Science ID 000307744700027
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EARLY INDICATION OF NEUROLOGICAL OUTCOMES AFTER CARDIAC ARREST USING QUANTITATIVE SOMATOSENSORY EVOKED POTENTIAL MONITORING
LIPPINCOTT WILLIAMS & WILKINS. 2009: A308
View details for Web of Science ID 000272509900599
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Neural Signals in Cortex and Thalamus during Brain Injury from Cardiac Arrest in Rats
Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society
IEEE. 2009: 5946?5949
Abstract
Previous research has shown that a characteristic burst-suppression (BS) pattern appears in EEG during the early recovery period following cardiac arrest (CA). To study cortical and subcortical neural activity underlying BS, extracellular activity in the parietal cortex and the centromedian nucleus of the thalamus and extradural EEG were recorded in a rodent CA model. Preliminary results show that during the BS, the cortical firing rate is extraordinarily high, and that bursts in EEG correlate to dense spikes in cortical neurons. An unexpected and novel observation is that 1) thalamic activity reappears earlier than cortical activity following CA, and 2) the correlation coefficient of cortical and thalamic activity rises during BS period. These results will help elucidate the mechanism of brain recovery after CA injury.
View details for Web of Science ID 000280543604212
View details for PubMedID 19965064
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Honors Biomedical Instrumentation - A Course Model for Accelerated Design
Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society
IEEE. 2009: 2015?2018
Abstract
A model for a 16-week Biomedical Instrumentation course is outlined. The course is modeled in such a way that students learn about medical devices and instrumentation through lecture and laboratory sessions while also learning basic design principles. Course material covers a broad range of topics from fundamentals of sensors and instrumentation, guided laboratory design experiments, design projects, and eventual protection of intellectual property, regulatory considerations, and entry into the commercial market. Students eventually complete two design projects in the form of a 'Challenge' design project as well as an 'Honors' design project. Sample problems students solve during the Challenge project and examples of past Honors projects from the course are highlighted.
View details for Web of Science ID 000280543601236
View details for PubMedID 19964766
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Information Theoretical Assessment of Neural Spiking Activity with Temperature Modulation
Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society
IEEE. 2009: 4990?4993
Abstract
Previous research has shown that hypothermia immediately after Cardiac Arrest (CA) improves neurological outcomes. In order to study how hypothermia affects neural spiking, cortical and subcortical neural activity was recorded from rodents. Consistent with previous findings, preliminary results show that the firing rate is proportional to the temperature. We also studied the information coded in the spike-timing information of individual neurons and observed that information content varies with temperature. Furthermore, there is an increased dependence between the cortex and sub-cortical structures such as the Thalamus during hypothermia. The latter is most likely an indicator of coupling between these highly connected structures in response to temperature manipulation leading to arousal after global cerebral ischemia.
View details for Web of Science ID 000280543603340
View details for PubMedID 19965028
