Papers by Eric Helfenbein
Circulation, Nov 22, 2011
Journal of Electrocardiology, Nov 1, 2021
Circulation, Nov 14, 2017
Circulation
Background: The advent of highly sensitive End-Tidal CO2 (ETCO2) sensors allows effective monitor... more Background: The advent of highly sensitive End-Tidal CO2 (ETCO2) sensors allows effective monitoring of intubated patients in EMS. Previous work has explored the use of ETCO2 monitoring in non-intubated patients with sensors placed in the nares. However, little is known about the effect of passive O2 delivery [nasal cannula (NC) or high-flow, non-rebreather mask (NRB)] on ETCO2 measurement. Objective: To compare ETCO2 measurements in non-intubated Traumatic Brain Injury (TBI) patients receiving O2 via NC vs. NRB in the field. Methods: A subset of cases from the EPIC EMS TBI Study (NIH-1R01NS071049) were evaluated (4/13-4/18). Non-intubated cases from 5 EMS agencies providing monitor data, including continuous ETCO2. Start and end segments were excluded to remove artifact from initiation (“ramp-up”) or termination of monitoring. Statistics: Wilcoxon rank-sum test, two-sample t-test, and Chi-squared test were used as appropriate. Linear regression compared continuous variables in adju...
Sensors, Apr 2, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
A systematic method for the improvement of the safety and reliability of automated guideway trans... more A systematic method for the improvement of the safety and reliability of automated guideway transit (AGT) vehicles via a failure detection algorithm is developed. This algorithm is based on the generalized likelihood ratio (GLR) method which detects failures by observing a departure of the vehicle system from an idealized linear vehicle model. The research explores the effect of model choice and complexity and the use of dual-redundant sensors on key detection performance issues. Detection ability of vehicle failures is demonstrated by vehicle simulations and experiments, and sensitivity to wind, grade, and maneuvers is examined. Detection methodology is developed for single AGT vehicles, and is extended to AGT systems employing vehicle-follower longitudinal control.
Circulation, 2016
Background: It is well established that prehospital hypoxia dramatically increases mortality in T... more Background: It is well established that prehospital hypoxia dramatically increases mortality in Traumatic Brain Injury (TBI). Thus, in EMS TBI research, case ascertainment and risk-adjustment are highly dependent upon documentation of in-field O2 saturation. Objective: To compare the rate of hypoxia identified by EMS personnel and documented in EMS patient care records (PCR) vs the actual rate of hypoxia recorded by continuous, non-invasive monitor in TBI. Methods: A subset of major TBI cases (moderate/severe) in the EPIC EMS TBI Study (NIH 1R01NS071049) were evaluated (3/30/13-6/26/15). Cases from 4 EMS agencies that report continuous monitor data (Philips MRx™) as part of EPIC were included. All monitor data available for post-hoc review were displayed and accessible to the providers during EMS care. We compared PCR documentation of hypoxia (O2 sat <90%) to actual recorded monitor data on each patient (Fisher’s Exact Test; α=0.05). Results: 77 cases were included [median age: 5...
Computers in Cardiology, 2005
ST elevation myocardial infarction (STEMI) in the right ventricle (RV) associated with right coro... more ST elevation myocardial infarction (STEMI) in the right ventricle (RV) associated with right coronary artery (RCA) occlusion is known to have high hospital mortality. The hypothesis tested in this study is: right precordial leads V4R and V5R help detect STEMI in the right ventricle. ECGs from 1,970 subjects were collected in Ruijin Hospital (n =1,342), Shanghai, China and Lund University Hospital, Lund (n = 565), Sweden. All ECGs were recorded with additional leads on the right precordial location in V4R and V5R. Our results show that the subjects with middle to upper RCA occlusion often show ST elevation in leads V4R and V5R and ST depression in lateral leads I, aVL, V5-V6, and are often undetected as STEMI or AMI in the standard 12-lead ECG. We conclude that adding V4R and V5R to standard ECG recording in assessing patients presenting with acute coronary syndrome is an easy and convenient way to increases the sensitivity of STEMI detection.
Computers in Cardiology, 2005, 2005
Normal ECG limits are age-dependent, particularly in infants and children, and diagnostic ECG cri... more Normal ECG limits are age-dependent, particularly in infants and children, and diagnostic ECG criteria are dependent on the availability of normal limits. As part of an ongoing study, we have evaluated selected ECG amplitudes and time intervals in a cohort of 1,166 healthy Chinese infants and children from Shanghai, China. We observe notable increases of QRS and QT intervals with age, a notable trend toward decreased R and increased S amplitudes in V2, and that T wave transition occurs at age 12 and that it occurs slightly earlier for males. We observe no notable gender differences in ECG parameters at age less than 12 years old, but that evolution differences begin to be manifested after age 8 years. The normal ECG limits in Asian infants and children are also compared with available data from North American infants and children.
Journal of Electrocardiology, 2011
ECG signals and conclusive diagnoses of perfusion imaging exerciseinduced ischemia. Conventional ... more ECG signals and conclusive diagnoses of perfusion imaging exerciseinduced ischemia. Conventional 10-second ECG signals were acquired from 1100 consenting subjects for the study. Relevant recurring morphology was isolated from the ECG segment from the peak of the QRS loop to the peak of the T loop by windowing, normalizing, and averaging to simulate the recurring shape of the "RT segment" in time domain. Harmonics were subsequently generated from the recurring RT segments by cosine transform, and a ratio of the frequency-domain harmonics, "Q4/P50," was computed for each of the 12 leads. For all 1100 subjects, standard examinations such as exercise stress tests with or without myocardial perfusion imaging (MPI) and coronary angiography were conducted as needed to form conclusive diagnoses of active ischemia. One-way analysis of variance (ANOVA) is conducted to group the ischemia "negative" and ischemia "positive" in which statistical significance is defined by a P level less than .05. In the grouping of the 1100 subjects based on conclusive diagnosis of ischemia, ANOVA of the Q4/P50 shows significance in all 12 leads except for leads III and V 2. Further analysis is done for the subset of 124 subjects who have undergone an MPI examination. In the grouping of these subjects for whom a conclusive MPI provided diagnosis of ischemia in any vessel territory, ANOVA of the Q4/P50 shows significance in leads I, II, aVR, V 1 , and V 6. Extending ANOVA to diagnoses by MPI vessel territory, the Q4/P50, given the limited numbers, shows significance in leads II and aVR for the RCA territory; in leads I, II, aVR, V 1 , V 5 , and V 6 for the left anterior descending territory; and in no lead as of yet for the LCx territory. This predictive method is potentially useful in the screening of ischemia using the conventional 12-lead resting ECG. Given the relatively small sample sizes, the quantitative ECG morphology indicators proposed in this study already achieve statistical significance in correlation with conclusive diagnoses of active ischemia.
The development and testing of incident detection algorithms was based on Los Angeles and Minneap... more The development and testing of incident detection algorithms was based on Los Angeles and Minneapolis freeway surveillance data. Algorithms considered were based on times series and pattern recognition techniques. Attention was given to the effects of geometrics, sensor configuration and weather, and methods were developed for detection malfunctioning sensors and for identifying the lane of an incident. This, the fourth volume, contains documentation of programs which can be implemented to provide the incident detection function in a real-time system, and programs which can be used for evaluating and calibrating incident detection algorithms. /FHWA/
Journal of Electrocardiology
Journal of Electrocardiology
Resuscitation, 2018
Aim: To study the influence of patient characteristics and unit ergonomics and human factors on t... more Aim: To study the influence of patient characteristics and unit ergonomics and human factors on the time to initiation of CPR. Methods: A single center study of children, 0 to 21 years old, admitted to an ICU who experienced cardiopulmonary arrest (CPA) requiring > 1 minute of chest compressions. Time of CPA was determined by analysis of continuous ECG, plethysmography, arterial blood pressure, and end-tidal CO 2 (EtCO 2) waveforms. Initiation of CPR was identified by the onset of cyclic artifact in the ECG waveform. Patient characteristics and unit ergonomics and human factors were examined including CPA cause, identification on the High-Risk Checklist (HRC), existing monitoring, ICU type, time of day, nursing shift change, and outcome.
Circulation, 2017
Background: Recent studies have shown that the lowest prehospital systolic blood pressure (SBP) i... more Background: Recent studies have shown that the lowest prehospital systolic blood pressure (SBP) is strongly associated with mortality across a remarkably wide range (far above 90 mmHg) in traumatic...
Circulation, 2018
Background: The advent of highly sensitive End-Tidal CO2 (ETCO2) sensors allows effective monitor... more Background: The advent of highly sensitive End-Tidal CO2 (ETCO2) sensors allows effective monitoring of intubated patients in many emergency care settings, including EMS. Previous work has explored the use of ETCO2 monitoring in non-intubated patients with sensors placed in the nares. However, nothing is known about the effect of passive oxygen delivery [nasal cannula (NC) or non-rebreather mask (NRB)] on ETCO2 measurement. Objective: To compare ETCO2 measurements in non-intubated Traumatic Brain Injury (TBI) patients receiving O2 via NC vs NRB in the prehospital setting. Methods: A subset of major TBI cases (CDC Barell Matrix Type-1) in the Excellence in Prehospital Injury Care (EPIC) TBI Study (NIH/NINDS-1R01NS071049; ClinicalTrials.gov-NCT01339702) were evaluated 4/13-3/17). Non-intubated cases from 6 EMS agencies providing monitor data (Philips MRx) were included when continuous ETCO2 data were available. Statistics: Two-tailed t test, α = 0.05. Results: The 104 included cases h...
Circulation, 2019
Objective: Little is known about End-Tidal CO 2 monitoring using nasal cannula sensors (NC-CO 2 )... more Objective: Little is known about End-Tidal CO 2 monitoring using nasal cannula sensors (NC-CO 2 ) in non-intubated patients. Objective: To describe the patterns of NC-CO 2 seen during the EMS care of spontaneously breathing major Traumatic Brain Injury (TBI) patients. Methods: Continuous NC-CO 2 data (Philips MRx™ monitors) were evaluated from non-intubated, major (moderate, severe, critical) TBI cases (4/13-5/17) in the EPIC TBI Study (NIH 1R01NS071049). Descriptive statistics were used to evaluate case and NC-CO 2 attributes. Results: Included were 92 cases [median age = 50 (range 10-91; 66% male)]. Median respiratory rate (RR) was >15/min in 87% of cases and >20/min in 53%. The highest median RR was 39. Sixteen cases (17%) had a median NC-CO 2 <20 mmHg, 37% (34) were 20-29, 18% (17) were 30-34, 25% (23) were 35-45. Two cases (2%) were 45-50, which has not been noted in this population previously. No case had a median NC-CO 2 >50. Several common NC-CO 2 patterns emerge...
Circulation, 2021
Background: Studies show that EMS patients are often inadvertently hyperventilated (HV), resultin... more Background: Studies show that EMS patients are often inadvertently hyperventilated (HV), resulting in hypocapnia. In TBI, HV markedly increases mortality. We evaluated continuous prehospital ETCO2 data in intubated TBI patients. Methods: Analysis of monitor data files (Philips MRx™) from a sample of intubated TBI cases in the EPIC Study (NIH-R01NS071049). Results: Among hundreds of cases, graphical display of continuous ETCO2 from 3 subjects dramatically exemplified commonly-occurring inadvertent HV. Fig 1 shows unrecognized HV lasting nearly 15 min. Fig 2 reveals nearly 14 min of increasing ventilatory rate and progressively worsening hypocapnia. Fig 3 shows nearly 4 min of HV that ends abruptly with clear, sudden recognition and slowing of ventilatory rate that leads to restoration of normal ETCO2 in only a few breaths. The corresponding EMS patient care records (PCR) failed to document the presence, severity, and duration of HV. Conclusions: In a study emphasizing prevention of H...
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Papers by Eric Helfenbein