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Clinical Focus

  • Critical Care Medicine
  • Cardiothoracic Anesthesiology
  • Extracorporeal Membrane Oxygenation
  • Quality Improvement
  • Fellow

Honors & Awards

  • Frank H. Sarnquist Recognition Award, Department of Anesthesiology, Perioperative and Pain Medicine (2019)
  • Best case presentation (second prize), Western Anesthesia Regional Conference (2018)
  • Best presentation in category ?Perioperative Challenges and Emergencies?, Western Anesthesia Regional Conference (2016)
  • TRANSFORM Patient Safety Program Award, Stanford Hospital & Clinics (April 2015)
  • TRANSFORM Patient Safety Program Award, Stanford Hospital & Clinics (September 2014)
  • Best Educational Abstract, Department of Anesthesiology, Perioperative, and Pain Medicine (2014)
  • George M.L. Sommerman Engineering Graduate Student Teaching Assistant Award, Johns Hopkins University (2010)
  • Center for Leadership Education Teaching Assistant Award of the Year, Johns Hopkins University (2008)
  • Richard J. Jones Outstanding Academic Achievement Award in Biomedical Engineering, Johns Hopkins University (2008)

Professional Education

  • MD, Stanford University School of Medicine, Medicine (2014)
  • MSE, Johns Hopkins University, Biomedical Engineering (2010)
  • BS, Johns Hopkins University, Biomedical Engineering (2008)


All Publications

  • Perioperative Implications of the 2020 American Heart Association Scientific Statement on Drug-Induced Arrhythmias-A Focused Review. Journal of cardiothoracic and vascular anesthesia Vanneman, M. W., Madhok, J., Weimer, J. M., Dalia, A. A. 2021


    The recently released American Heart Association (AHA) scientific statement on drug-induced arrhythmias discussed medications commonly associated with bradycardia, supraventricular tachycardias, and ventricular arrhythmias. The foundational data for this statement were collected from general outpatient and inpatient populations. Patients undergoing surgical and minimally invasive treatments are a unique subgroup, because they may experience hemodynamic changes associated with anesthesia and their procedure, receive multiple drug combinations not given in either inpatient or outpatient settings, or experience postprocedural inflammatory syndromes. Accordingly, the generalizability of the AHA scientific statement to this perioperative population is unclear. This focused review highlights important aspects of the new AHA scientific statement and their application to the perioperative setting. The authors review medications frequently encountered and given by anesthesiologists and their risk of drug-induced arrhythmias and discuss common anesthetic and adjunctive medications and their associated risks of bradycardia, atrial fibrillation, torsades de pointes, and drug-induced Brugada syndrome. In many instances, the risk of arrhythmia reported by the AHA scientific statement in the general population appeared to be higher than found in perioperative arenas. Furthermore, the authors discuss the arrhythmia risk of additional medications commonly ordered or administered by anesthesiologists that are not included in the AHA scientific statement. As patient and procedural complexity increases and novel anesthetic combinations propagate, further research and observational studies will be required to delineate further perioperative risks for drug-induced arrhythmia.

    View details for DOI 10.1053/j.jvca.2021.05.008

    View details for PubMedID 34144871

  • The Use of Factor Eight Inhibitor Bypass Activity (FEIBA) for the Treatment of Perioperative Hemorrhage in Left Ventricular Assist Device Implantation. Journal of cardiothoracic and vascular anesthesia O'Donnell, C., Rodriguez, A. J., Madhok, J., Sharifi, H., Wang, H., O'Brien, C. G., Boyd, J., Hiesinger, W., Hsu, J., Hill, C. C. 2021


    OBJECTIVE: To test the hypothesis that factor eight inhibitor bypassing activity (FEIBA) can be used to control bleeding following left ventricular assist device (LVAD) implantation without increasing the 14-day composite thrombotic outcome of pump thrombus, ischemic cerebrovascular accidents, pulmonary embolism, and deep venous thrombosis.DESIGN: Retrospective cohort study.SETTING: Academic hospital.PARTICIPANTS: Three hundred nineteen consecutive patients who underwent LVAD implantation (December 1, 2009 to December 30, 2018).INTERVENTION: FEIBA administered to control perioperative hemorrhage.MEASUREMENTS AND MAIN RESULTS: The 82 patients (25.7%) in the FEIBA cohort had more risk factors for perioperative hemorrhage, such as lower preoperative platelet count (169 ▒ 66 v 194 ▒ 68?*?103/mL, p?=?0.004), prior cardiac surgery (36.6% v 21.9%, p?=?0.008), and longer cardiopulmonary bypass (CPB) time (100.3 v 75.2 minutes, p?=?0.001) than the 237 controls. After 16.6 units (95% CI: 14.3-18.9) of blood products were given, 992 units (95% CI: 821-1163) of FEIBA were required to control bleeding in the FEIBA cohort. Compared to the controls, there were no differences in the 14-day composite thrombotic outcome (11.0% v 7.6%, p?=?0.343) or mortality rate (3.7% v 1.3%, p?=?0.179). Multivariate logistical regression identified preoperative international normalized ratio (odds ratio [OR]: 1.30, 95% CI: 1.04-1.62) and CPB time (OR: 1.11, 95% CI: 1.02-1.20) as risk factors for 14-day thrombotic events, but FEIBA usage was not associated with an increased risk.CONCLUSIONS: In this retrospective cohort study, the use of FEIBA (1,000 units, 13 units/kg) to control perioperative hemorrhage following LVAD implantation was not associated with increases in mortality or composite thrombotic outcome.

    View details for DOI 10.1053/j.jvca.2021.04.030

    View details for PubMedID 34034934

  • Antithrombin in Extracorporeal Membrane Oxygenation: To Replenish or Not to Replenish? Critical care medicine Madhok, J., Ruoss, S. J. 2021; 49 (4): e480?e481

    View details for DOI 10.1097/CCM.0000000000004812

    View details for PubMedID 33731637

  • First lung and kidney multi-organ transplant following COVID-19 Infection. The Journal of heart and lung transplantation : the official publication of the International Society for Heart Transplantation Guenthart, B. A., Krishnan, A., Alassar, A., Madhok, J., Kakol, M., Miller, S., Cole, S. P., Rao, V. K., Acero, N. M., Hill, C. C., Cheung, C., Jackson, E. C., Feinstein, I., Tsai, A. H., Mooney, J. J., Pham, T., Elliott, I. A., Liou, D. Z., La Francesca, S., Shudo, Y., Hiesinger, W., MacArthur, J. W., Brar, N., Berry, G. J., McCarra, M. B., Desai, T. J., Dhillon, G. S., Woo, Y. J. 2021


    As the world responds to the global crisis of the COVID-19 pandemic an increasing number of patients are experiencing increased morbidity as a result of multi-organ involvement. Of these, a small proportion will progress to end-stage lung disease, become dialysis dependent, or both. Herein, we describe the first reported case of a successful combined lung and kidney transplantation in a patient with COVID-19. Lung transplantation, isolated or combined with other organs, is feasible and should be considered for select patients impacted by this deadly disease.

    View details for DOI 10.1016/j.healun.2021.02.015

    View details for PubMedID 34059432

  • Specific Considerations for Venovenous Extracorporeal Membrane Oxygenation During Coronavirus Disease 2019 Pandemic. ASAIO journal (American Society for Artificial Internal Organs : 1992) Guihaire, J. n., Owyang, C. G., Madhok, J. n., Laverdure, F. n., Gaillard, M. n., Girault, A. n., Lebreton, G. n., Mercier, O. n. ; 66 (10): 1069?72


    Extracorporeal membrane oxygenation (ECMO) is recognized as organ support for potentially reversible acute respiratory distress syndrome (ARDS). However, limited resource during the outbreak and the coagulopathy associated with coronavirus disease 2019 (COVID-19) make the utilization of venovenous (VV) ECMO highly challenging. We herein report specific considerations for cannulation configurations and ECMO management during the pandemic. High blood flow and anticoagulation at higher levels than usual practice for VV ECMO may be required because of thrombotic hematologic profile of COVID-19. Among our first 24 cases (48.8?▒?8.9 years), 17 patients were weaned from ECMO after a mean duration of 19.0?▒?10.1 days and 16 of them have been discharged from ICU.

    View details for DOI 10.1097/MAT.0000000000001251

    View details for PubMedID 33136589

  • Rescue of Nimodipine-Induced Refractory Vasoplegia With Hydroxocobalamin in Subarachnoid Hemorrhage: A Case Report. Critical care explorations Clifford, K. M., Madhok, J., Murray, N. M., Mohindra, V. 2020; 2 (10): e0205


    Background: We report a case of refractory vasoplegia after nimodipine administration that was unresponsive to triple vasopressor therapy and was rescued by IV hydroxocobalamin.Case Summary: An 84-year-old male presented comatose from a subarachnoid hemorrhage and developed severe hypotension unresponsive to three vasopressors following a single dose of enteral nimodipine. Multisystem point-of-care ultrasonography ruled out alternate etiologies of shock, indicating that this was likely a vasoplegic state caused by nimodipine. We administered 5 grams of IV hydroxocobalamin over 15 minutes due to the possibility of impaired nitric oxide metabolism as the driver of vasoplegia. This led to immediate improvement in hemodynamics and rapid discontinuation of vasopressors. The patient experienced chromaturia but no other adverse effects due to hydroxocobalamin.Conclusions: Nimodipine administration is a standard practice for patients with aneurysmal subarachnoid hemorrhage to reduce unfavorable outcomes from cerebral vasospasm. Although mild hypotension is a common side effect of nimodipine, in rare cases, it may become profound, leading to refractory vasoplegia. There is no evidence-base for reversal agents for nimodipine-induced vasoplegia, and this case is the first to demonstrate successful use of hydroxocobalamin as a potential rescue therapy. We also propose an algorithm for treatment of vasoplegia with consideration of medications that act on nitric oxide-mediated vasodilation and their side-effect profiles.

    View details for DOI 10.1097/CCE.0000000000000205

    View details for PubMedID 33063021

  • Rethinking sedation during prolonged mechanical ventilation for COVID-19 respiratory failure. Anesthesia and analgesia Madhok, J., Mihm, F. G. 2020

    View details for DOI 10.1213/ANE.0000000000004960

    View details for PubMedID 32398430

  • Mortality of Patients Requiring Escalation to Intensive Care within 24 Hours of Admission in a Mixed Medical-Surgical Population. Clinical medicine & research Leong, J. n., Madhok, J. n., Lighthall, G. K. 2020


    Delayed intensive care unit admissions are associated with increased mortality. We present a retrospective study looking at whether indirect admissions to the ICU within 24 hours of hospital admission were associated with increased mortality.Retrospective cohort study SETTING: Mixed medical-surgical ICU at a large tertiary United States Veterans Affairs (VA) Hospital System POPULATION: The patients were a mix of medical and surgical patients. Patients included both those directly admitted from the operating room as well as those escalated to the ICU after initial admission to the ward (indirect admission).All admissions to a medical-surgical ICU from 2008 to 2013 were included in the study. The database was queried for time and location where the admission originated. Separate lists were created for patients with severe sepsis, patients who transferred to the ICU within the first 24 hours, and patients who had rapid response or code team activations. Analysis was applied to the whole group and to medical and surgical subpopulations.A total of 3,862 ICU admissions were studied. Univariate analysis indicated an impact of delayed admission on whole group and surgical patients, however multivariate analysis indicated a significant effect of delayed admission on 1-year surgical mortality. Multivariate analysis also showed a consistent effect of age, ICU length of stay and cardiac arrest on mortality of both medical and surgical ICU patients.In a large retrospective study, surgical patients had increased 1-year mortality if they required escalation to the ICU within 24 hours of hospital admission. This result was not replicated in medical patients, possibly related to a burden of illness that could not be altered by earlier care.

    View details for DOI 10.3121/cmr.2019.1497

    View details for PubMedID 31959671

  • Traumatic Pneumothorax Presenting as a Subcutaneous "Airball". American journal of respiratory and critical care medicine Madhok, J. n., Madani, M. H., Leung, A. N., Mihm, F. n. 2020

    View details for DOI 10.1164/rccm.202006-2515IM

    View details for PubMedID 33197203

  • Catecholamine-induced cerebral vasospasm and multifocal infarctions in pheochromocytoma. Endocrinology, diabetes & metabolism case reports Madhok, J. n., Kloosterboer, A. n., Venkatasubramanian, C. n., Mihm, F. G. 2020; 2020


    We report the case of a 76-year-old male with a remote history of papillary thyroid cancer who developed severe paroxysmal headaches in the setting of episodic hypertension. Brain imaging revealed multiple lesions, initially of inconclusive etiology, but suspicious for metastatic foci. A search for the primary malignancy revealed an adrenal tumor, and biochemical testing confirmed the diagnosis of a norepinephrine-secreting pheochromocytoma. Serial imaging demonstrated multiple cerebral infarctions of varying ages, evidence of vessel narrowing and irregularities in the anterior and posterior circulations, and hypoperfusion in watershed areas. An exhaustive work-up for other etiologies of stroke including thromboembolic causes or vasculitis was unremarkable. There was resolution of symptoms, absence of new infarctions, and improvement in vessel caliber after adequate alpha-adrenergic receptor blockade for the management of pheochromocytoma. This clinicoradiologic constellation of findings suggested that the etiology of the multiple infarctions was reversible cerebral vasoconstriction syndrome (RCVS). Pheochromocytoma remains a poorly recognized cause of RCVS. Unexplained multifocal cerebral infarctions in the setting of severe hypertension should prompt the consideration of a vasoactive tumor as the driver of cerebrovascular dysfunction. A missed or delayed diagnosis has the potential for serious neurologic morbidity for an otherwise treatable condition.The constellation of multifocal watershed cerebral infarctions of uncertain etiology in a patient with malignant hypertension should trigger the consideration of undiagnosed catecholamine secreting tumors, such as pheochromocytomas and paragangliomas. Reversible cerebral vasoconstriction syndrome is a serious but reversible cerebrovascular manifestation of pheochromocytomas that may lead to strokes (ischemic and hemorrhagic), seizures, and cerebral edema. Alpha-adrenergic receptor blockade can reverse cerebral vasoconstriction and prevent further cerebral ischemia and infarctions. Early diagnosis of catecholamine secreting tumors has the potential for reducing neurologic morbidity and mortality in patients presenting with cerebrovascular complications.

    View details for DOI 10.1530/EDM-20-0078

    View details for PubMedID 32820130

  • Retrospective Analysis of Peri-Intubation Hypoxemia During the Coronavirus Disease 2019 Epidemic Using a Protocol for Modified Airway Management. A&A practice Madhok, J. n., Vogelsong, M. A., Lee, T. C., Wilson, J. G., Mihm, F. n. 2020; 14 (14): e01360


    This single-center retrospective study evaluated a protocol for the intubation of patients with confirmed or suspected coronavirus disease 2019 (COVID-19). Twenty-one patients were intubated, 9 of whom were found to have COVID-19. Adherence to the airway management protocol was high. COVID-19 patients had lower peripheral capillary oxygen saturation by pulse oximetry (Spo2) nadirs during intubation (Spo2, 73% [72%-77%] vs 89% [86%-94%], P = .024), and a greater percentage experienced severe hypoxemia defined as Spo2 ?80% (89% vs 25%, P = .008). The incidence of severe hypoxemia in COVID-19 patients should be considered in the development of guidelines that incorporate high-flow nasal cannula and noninvasive positive pressure ventilation.

    View details for DOI 10.1213/XAA.0000000000001360

    View details for PubMedID 33449537

  • Anesthetic Considerations for Liver Transplantation in a Patient with Mitochondrial Neurogastrointestinal Encephalopathy Syndrome. Cureus Madhok, J. n., Leong, J. n., Cohn, J. n. 2019; 11 (6): e5038


    Mitochondrial neurogastrointestinal encephalopathy (MNGIE) is a rare, complex mitochondrialádisorder with variable phenotypes caused by a defect in the TYMP gene that codes for the thymidine phosphorylase enzyme. Orthotopic liver transplantation (OLT) has been proposed as a curative option for patients by using the liver as a source to restore thymidine phosphorylase levels in the body. Anesthetic considerations for this syndrome have not been clearly outlined in the past. We describe the clinical presentation of a young woman with MNGIE, her perioperative assessment, and intraoperative management during liver transplantation.

    View details for DOI 10.7759/cureus.5038

    View details for PubMedID 31501730

    View details for PubMedCentralID PMC6721878

  • Curricular Innovations for Medical Students in Palliative and End-of-Life Care: A Systematic Review and Assessment of Study Quality JOURNAL OF PALLIATIVE MEDICINE DeCoste-Lopez, J., Madhok, J., Harman, S. 2015; 18 (4): 338-349


    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

  • Hypothermia Amplifies Somatosensory-evoked Potentials in Uninjured Rats JOURNAL OF NEUROSURGICAL ANESTHESIOLOGY Madhok, J., Wu, D., Xiong, W., Geocadin, R. G., Jia, X. 2012; 24 (3): 197-202


    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

  • Study of the origin of short- and long-latency SSEP during recovery from brain ischemia in a rat model NEUROSCIENCE LETTERS Wu, D., Anastassios, B., Xiong, W., Madhok, J., Jia, X., Thakor, N. V. 2010; 485 (3): 157-161


    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

  • Quantitative assessment of somatosensory-evoked potentials after cardiac arrest in rats: Prognostication of functional outcomes CRITICAL CARE MEDICINE Madhok, J., Maybhate, A., Xiong, W., Koenig, M. A., Geocadin, R. G., Jia, X., Thakor, N. V. 2010; 38 (8): 1709-1717


    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

  • Evolution of somatosensory evoked potentials after cardiac arrest induced hypoxic-ischemic injury RESUSCITATION Xiong, W., Koenig, M. A., Madhok, J., Jia, X., Puttgen, H. A., Thakor, N. V., Geocadin, R. G. 2010; 81 (7): 893-897


    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

  • 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) Madhok, J., Iyer, S., Thakor, N. V., Maybhate, A. IEEE. 2010: 2798?2801


    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

  • Discovery of Long-Latency Somatosensory Evoked Potentials as a Marker of Cardiac Arrest Induced Brain Injury Wu, D., Madhok, J., Choi, Y., Jia, X., Thakor, N. V., Herold, K. E., Bentley, W. E., Vossoughi, J. SPRINGER. 2010: 101?4
  • 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 Zhang, D., Choi, Y., Madhok, J., Jia, X., Koenig, M., Thakor, N. IEEE. 2009: 5946?5949


    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

  • Honors Biomedical Instrumentation - A Course Model for Accelerated Design Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society Madhok, J., Smith, R. J., Thakor, N. V. IEEE. 2009: 2015?2018


    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

  • Information Theoretical Assessment of Neural Spiking Activity with Temperature Modulation Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society Madhok, J., Jia, X., Choi, Y., Zhang, D., Thakor, N. IEEE. 2009: 4990?4993


    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

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