Joseph J. Korfhagen

A Novel Tool for Evaluation of Mild Traumatic Brain Injury Patients in the Emergency Department: Does Robotic Assessment of Neuromotor Performance Following Injury Predict the Presence of Postconcussion Symptoms at Follow-up?

OBJECTIVES Postconcussion symptoms (PCS) are a common complication of mild traumatic brain injury (TBI). Currently, there is no validated clinically available method to reliably predict at the time of injury who will subsequently develop PCS. The purpose of this study was to determine if PCS following mild TBI can be predicted during the initial presentation to an emergency department (ED) using a novel robotic-assisted assessment of neurologic function. METHODS All patients presenting to an urban ED with a chief complaint of head injury within the preceding 24 hours were screened for inclusion from March 2013 to April 2014. The enrollment criteria were as follows: 1) age of 18 years or greater, 2) ability and willingness to provide written informed consent, 3) blunt head trauma and clinical diagnosis of isolated mild TBI by the treating physician, and 4) blood alcohol level of <100 mg/dL. Eligible mild TBI patients were enrolled and their neuromotor function was assessed in the ED using a battery of five tests that cover a range of proprioceptive, visuomotor, visuospatial, and executive function performance metrics. At 3 weeks postinjury, participants were contacted via telephone to complete the Rivermead Post-Concussion Symptoms Questionnaire to assess the presence of significant PCS. RESULTS A total of 66 mild TBI patients were enrolled in the study with 42 of them completing both the ED assessment and the follow-up; 40 patients were included in the analyses. The area under the receiver operating characteristic curve (AUC) for the entire test battery was 0.72 (95% confidence interval [CI] = 0.54 to 0.90). The AUC for tests that primarily measure visuomotor and proprioceptive performance were 0.80 (95% CI = 0.65 to 0.95) and 0.71 (95% CI = 0.53 to 0.89), respectively. CONCLUSIONS The robotic-assisted test battery has the ability to discriminate between subjects who developed PCS and those who did not. Additionally, poor visuomotor and proprioceptive performance were most strongly associated with subsequent PCS.

Randomized Controlled Noninferiority Trial Comparing Daptomycin to Vancomycin for the Treatment of Complicated Skin and Skin Structure Infections in an Observation Unit

BACKGROUND Incidence of methicillin-resistant Staphylococcus aureus (MRSA) is increasing in complicated skin and skin structure infection (cSSSI) presenting to emergency departments (EDs). Treatment is heterogeneous and can require inpatient admission to an observation unit (OU). Vancomycin is commonly used in the OU for treatment, but increasing MRSA resistance to vancomycin suggests the need for alternatives. Daptomycin is an alternative but it is not known how it compares with vancomycin. OBJECTIVE This study tested the hypothesis that daptomycin is noninferior to vancomycin for the treatment of cSSSI in an OU, using a relative risk (RR) of 1.3 as the noninferiority limit. METHODS Subjects admitted to an ED-based OU with a diagnosis of cSSSI were eligible. Consenting subjects were randomized 1:1 to intravenous (i.v.) vancomycin at 15 mg/kg dosing every 12 h or i.v. daptomycin at 4 mg/kg once. Subjects were followed until they met objective criteria for discharge home or hospital admission. Discharged patients were prescribed 10-14 days of oral cephalexin and trimethoprim-sulfamethoxazole, or clindamycin if allergic to either of these medications. The primary endpoint was meeting objective discharge criteria with no change in antibiotic therapy or return to the ED for the same cellulitis within 30 days of OU discharge. RESULTS There were 100 patients enrolled. RR for satisfying the endpoint was 1.07 (95% confidence interval 0.58-1.98) for daptomycin compared with vancomycin. Hospital admission rates were 36% and 32% for daptomycin and vancomycin treatment, respectively. CONCLUSION Daptomycin was not inferior to vancomycin in the treatment of cSSSI in an OU.

Integration of New Technology for Research in the Emergency Department: Feasibility of Deploying a Robotic Assessment Tool for Mild Traumatic Brain Injury Evaluation

The objective of this paper is to demonstrate the effective deployment of a robotic assessment tool for the evaluation of mild traumatic brain injury (mTBI) patients in a busy, resource-constrained, urban emergency department (ED). Methods: Functional integration of new robotic technology for research in the ED presented several obstacles that required a multidisciplinary approach, including participation from electrical and computer engineers, emergency medicine clinicians, and clinical operations staff of the hospital. Our team addressed many challenges in deployment of this advanced technology including: 1) adapting the investigational device for the unique clinical environment; 2) acquisition and maintenance of appropriate testing space for point-of-care assessment; and 3) dedicated technical support and upkeep of the device. Upon successful placement of the robotic device in the ED, the clinical study required screening of all patients presenting to the ED with complaints of head injury. Eligible patients were enrolled and tested using a robot-assisted test battery. Three weeks after the injury, patients were contacted to complete follow-up assessments. Results: Adapting the existing technology to meet anticipated physical constraints of the ED was performed by engineering a mobile platform. Due to the large footprint of the device, it was frequently moved before ultimately being fully integrated into the ED. Over 14 months, 1423 patients were screened. Twenty-eight patients could not be enrolled because the device was unavailable due to operations limitations. Technical problems with the device resulted in failure to include 20 patients. A total of 66 mTBI patients were enrolled and 42 of them completed both robot-assisted testing and follow-up assessment. Successful completion of screening and enrollment demonstrated that the challenges associated with integration of investigational devices into the ED can be effectively addressed through a collaborative patient-oriented research model. Conclusion: Effective deployment and use of new robotic technology for research in an urban academic ED required significant planning, coordination, and collaboration with key personnel from multiple disciplines. Clinical Impact: A pilot clinical study on mTBI patients using the robotic device provided useful data without disrupting the ED workflow. Integration of this technology into the ED serves as an important step toward pursing active clinical research in an acute care setting.

Quantitative assessment of post-concussion syndrome following mild traumatic brain injury using robotic technology

Post-Concussion Syndrome (PCS) is a common sequelae of mild Traumatic Brain Injury (mTBI). Currently, there is no reliable test to determine which patients will develop PCS following an mTBI. As a result, clinicians are challenged to identify patients at high risk for subsequent PCS. Hence, there is a need to develop an objective test that can guide clinical risk stratification and predict the likelihood of PCS at the initial point of care in an Emergency Department (ED). This paper presents the results of robotic-assisted neurologic testing completed on mTBI patients in the ED and its ability to predict PCS at 3 weeks post-injury. Preliminary results show that abnormal proprioception, as measured using robotic testing is associated with higher risk of developing PCS following mTBI. In this pilot study, proprioceptive measures obtained through robotic testing had a 77% specificity (95CI: 46%-94%) and a 64% sensitivity (95CI: 41%-82%).

MW blood sample characterization using co-axial transmission line

Microwave Tomography (MWT) is being developed as an accurate detection of hemorrhagic strokes using microwaves. A transmission line technique is used to measure the relative permittivity of blood as a function of frequency and is presented to provide insight on an appropriate operating frequency for MWT. A response calibration method is used on a coaxial sample holder to accurately measure the scattering parameters of and characterization of liquid samples. This paper demonstrates the ability to accurately measure liquid samples by replacing the coaxial line dielectric with liquid. Experimental results from water and 99% isopropyl alcohol are compared against known values to provide verification of the coaxial airline to accurately measure blood samples in the microwave region.

In vivo testing of a non-invasive prototype device for the continuous monitoring of intracerebral hemorrhage.

BACKGROUND Intracerebral hemorrhage (ICH) is a stroke subtype with the highest mortality rate. Hematoma expansion and re-bleeding post-ICH are common and exacerbate the initial cerebral insult. There is a need for continuous monitoring of the neurologic status of patients with an ICH injury. NEW METHOD A prototype device for non-invasive continuous monitoring of an ICH was developed and tested in vivo using a porcine ICH model. The device consists of receiving and transmitting antennae in the 400-1000 MHz frequency range, placed directly in line with the site of the ICH. The device exploits the differences in the dielectric properties and geometry of tissue media of a healthy brain and a brain with an ICH injury. The power received by the receiving antenna is measured and the percent change in power received immediately after infusion of blood and 30 min after the infusion, allowing for the blood to clot, is calculated. RESULTS An increase in the received power in the presence of an ICH is observed at 400 MHz, consistent with previous in vitro studies. Frequency sweep experiments show a maximum percent change in received power in the 750-1000 MHz frequency range. COMPARISON WITH EXISTING METHODS Currently, CT, MRI and catheter angiography (CA) are the main clinical neuroimaging modalities. However, these techniques require specialized equipment and personnel, substantial time, and patient-transportation to a radiology suite to obtain results. Moreover, CA is invasive and uses intra-venous dye or vascular catheters to accomplish the imaging. CONCLUSIONS The device has the potential to significantly improve neurologic care in the critically ill brain-injured patient.

Effect of skull anatomy on intracranial acoustic fields for ultrasound-enhanced thrombolysis

Transcranial ultrasound improves thrombolytic drug efficacy in ischemic stroke therapy. The goal of this study was to determine the ideal ultrasound parameters for obtaining peak rarefactional pressures exceeding the stable cavitation threshold at the left anterior clinoid process (lACP) of the skull. This location is near the origin of the middle cerebral artery, a common site for ischemic stroke. For 0.5, 1.1 and 2.0-MHz ultrasound transducers, pulse repetition frequencies (PRF) ranging from 5.4-8.0 kHz were studied at a 50% duty cycle. Attenuation and ultrasound beam distortion were measured from a cadaveric human skull. Each transducer was placed near the left temporal bone such that the unaberrated maximum acoustic pressure would be located at the lACP. A hydrophone measured the acoustic field around the lACP. Free-field measurements were taken in the same locations to determine attenuation and beam focus distortion. For 5 skulls, the average pressure attenuation at the lACP was 68±19, 91±5.1, and 94...

Validation of a finite-difference acoustic propagation model of transcranial ultrasound

Adjuvant ultrasound exposure improves rtPA thrombolysis in stroke patients. Transmission of 120-kHz ultrasound through the temporal bone is efficient but exhibits skull-dependent distortion and reflection. Numerical models of acoustic propagation through human skull based on computed tomography (CT) data have been developed. The objective of our study was to validate a finite-difference model of transcranial ultrasound quantitatively. The acoustic fields from a two-element annular array (120 kHz and 60 kHz) were acquired in four ex-vivo human skulls with a calibrated hydrophone (10 kHz-800 kHz frequency range). The spatial distributions of the acoustomechanical properties of each skull were obtained from CT scans and used for simulations. Predicted acoustic fields and waveform shapes were compared with corresponding hydrophone measurements and were in good agreement. Transmitted wave amplitudes were systematically underestimated (14%) and reflected wave amplitudes were overestimated (30%). The acoustic im...