Abstract 13048: A Simple Model to Describe the Relationship Between Compression Force and Depth During CPR

Aim: The relationship between force and depth during manual chest compressions depends on the patient and on the dynamics with which the rescuer applies the force. Force-depth models with many fitting parameters have been proposed making physical interpretation complicated. The aim of this work was to design a simpler force-depth model, accommodating anticipated differences in compression and recoil phases. Materials and Methods: Force and acceleration signals were extracted from out-of-hospital-cardiac arrest (OHCA) defibrillator recordings (TVF&R, OR, USA), equipped with CPR technology. Compression depth and velocity signals were computed from acceleration. We analyzed intervals of 20-s within the 1st min of chest compressions. Our model decomposes the applied force as the sum of an elastic and a damped term, considering different damping coefficients for the compression and recoil phases. Coefficient of elasticity was calculated at the instant of maximum compression depth (null velocity) and damping coefficients at the instants of maximum compression and recoil velocities. The estimated depth signal is shown in the figure. The goodness of the model was assessed through the determination coefficient R 2 . Results: We analyzed 1,074 compressions from 30 OHCA recordings. Median (IQR) compression depth was 4.6 (4.0-5.4) cm; compression rate was 107 (102–113) cpm; coefficient of elasticity was 100.67 (78.95–125.01) N/cm; compression damping coefficient was 2.57 (1.84–3.29) N/(cm/s) and recoil damping coefficient was 3.59 (2.58–4.90) N/(cm/s). Median R 2 was 0.993 (0.984–0.996). Conclusions: This model, derived using fewer parameters, could help with the interpretation of the mechanical properties of the chest during CPR. It may also be useful for the assessment of inter-patient differences with age, sex, and body constitution, as well as of the evolution of elasticity and damping of patient’s chest during the course of resuscitation.

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Assessing the relationship between release velocity, compression depth and decompression time in manual chest compressions

Resuscitation ◽

10.1016/j.resuscitation.2017.08.059 ◽

2017 ◽

Vol 118 ◽

pp. e20

Author(s):

Digna M. González-Otero ◽

Jesus Ruiz ◽

Sofía Ruiz de Gauna ◽

Jose Julio Gutierrez ◽

Mohamud Daya ◽

...

Keyword(s):

Chest Compressions ◽

Compression Depth ◽

The Relationship ◽

Decompression Time

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The Influence of Support Hardware and Piping System Seismic Response on Snubber Support Damping

Journal of Pressure Vessel Technology ◽

10.1115/1.2842329 ◽

1997 ◽

Vol 119 (4) ◽

pp. 451-456 ◽

Cited By ~ 2

Author(s):

C. Lay ◽

O. A. Abu-Yasein ◽

M. A. Pickett ◽

J. Madia ◽

S. K. Sinha

Keyword(s):

Seismic Response ◽

Fundamental Frequency ◽

Damping Ratio ◽

Damping Coefficient ◽

Piping System ◽

Nodal Displacement ◽

Damping Coefficients ◽

Fundamental Frequencies ◽

Piping Systems

The damping coefficients and ratios of piping system snubber supports were found to vary logarithmically with pipe support nodal displacement. For piping systems with fundamental frequencies in the range of 0.6 to 6.6 Hz, the support damping ratio for snubber supports was found to increase with increasing fundamental frequency. For 3-kip snubbers, damping coefficient and damping ratio decreased logarithmically with nodal displacement, indicating that the 3-kip snubbers studied behaved essentially as coulomb dampers; while for the 10-kip snubbers studied, damping coefficient and damping ratio increased logarithmically with nodal displacement.

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Study onYang-XuUsing Body Constitution Questionnaire and Blood Variables in Healthy Volunteers

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2016/9437382 ◽

2016 ◽

Vol 2016 ◽

pp. 1-7 ◽

Cited By ~ 7

Author(s):

Hong-Jhang Chen ◽

Yii-Jeng Lin ◽

Pei-Chen Wu ◽

Wei-Hsiang Hsu ◽

Wan-Chung Hu ◽

...

Keyword(s):

Healthy Subjects ◽

Logistic Regression Model ◽

Cross Validation ◽

Blood Biomarkers ◽

Metabolic Characteristics ◽

Body Constitution ◽

Leave One Out ◽

The Relationship ◽

Fold Cross Validation ◽

Blood Variables

Traditional Chinese medicine (TCM) formulates treatment according to body constitution (BC) differentiation. Different constitutions have specific metabolic characteristics and different susceptibility to certain diseases. This study aimed to assess theYang-Xuconstitution using a body constitution questionnaire (BCQ) and clinical blood variables. A BCQ was employed to assess the clinical manifestation ofYang-Xu. The logistic regression model was conducted to explore the relationship between BC scores and biomarkers. Leave-one-out cross-validation (LOOCV) and K-fold cross-validation were performed to evaluate the accuracy of a predictive model in practice. Decision trees (DTs) were conducted to determine the possible relationships between blood biomarkers and BC scores. According to the BCQ analysis, 49% participants without any BC were classified as healthy subjects. Among them, 130 samples were selected for further analysis and divided into two groups. One group comprised healthy subjects without any BC (68%), while subjects of the other group, named as the sub-healthy group, had three BCs (32%). Six biomarkers, CRE, TSH, HB, MONO, RBC, and LH, were found to have the greatest impact on BCQ outcomes inYang-Xusubjects. This study indicated significant biochemical differences inYang-Xusubjects, which may provide a connection between blood variables and theYang-XuBC.

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Abstract 439: Using the Time Interval Between R-Wave Detection and Maximum Compression Pressure to Target and Validate Delivery of Synchronized Chest Compressions During Pseudo Electro-Mechanical Dissociation

Circulation ◽

10.1161/circ.140.suppl_2.439 ◽

2019 ◽

Vol 140 (Suppl_2) ◽

Author(s):

Joshua W Lampe ◽

Jeff R Gould ◽

Karen L Moodie ◽

Zachary P Soucy ◽

Peter S Burrage ◽

...

Keyword(s):

Blood Flow ◽

Time Interval ◽

Hemodynamic Parameters ◽

Chest Compressions ◽

Compression Pressure ◽

Carotid Blood Flow ◽

Maximum Compression ◽

Local Maxima ◽

Blood Flows ◽

Mechanical Dissociation

Introduction: The treatment of pseudo electro-mechanical dissociation (P-EMD) with standard chest compressions leads to some compressions that interfere with blood flow created by ventricular contraction and others that are synergistic. We have previously reported that the hemodynamics generated by standard chest compressions (StdCPR) depended on the time interval between the R-wave and the maximum compression pressure (t_int). Our goal was to use the t_int to identify the optimal timing for compression synchronization and to validate the delivery of synchronized chest compressions. Methods: Eight animals underwent surgical preparation and were exposed to hypoxia to induce P-EMD. The treatment period was divided into eight 45 sec epochs during which the P-EMD was left untreated or was treated with StdCPR or chest compressions synchronized to the R-wave in the ECG (SyncCPR). For each heart beat t_int was calculated as t peak AOP - t Rwave , blood pressures were averaged, and blood flows were integrated. 1,598 chest compressions were analyzed. The location of local extrema in hemodynamic parameters as a function of positive t_int values were identified recursively by dividing the range of t_int values into increasing numbers of bins and determining which bin had the highest mean value. Results: Blood flows and pressures exhibited a non-linear dependence on t_int. The maximum CPP occurred at t_int = 90 ±2.3 ms. The maximum aortic pressure occurred at t_int = 70 ±2.3 ms. The minimum right atrial pressure occurred at t_int = 280 ±2.3 ms. The maximum carotid blood flow occurred at t_int = 100 ±2.3 ms. The maximum jugular blood flow occurred at t_int = 400 ±2.3 ms. Unsynchronized chest compressions resulted in a t_int of -21 ± 170 ms. Synchronized chest compressions resulted in a t_int of 119 ± 13 ms. Conclusions: Local maxima and minima during StdCPR were identified in several hemodynamic parameters, but the extrema were not perfectly co-located. It appears that a t_int of 90-100 ms could be optimal. SyncCPR were delivered at 119 ms, which is not far from the local maxima observed for CPP and carotid blood flow.

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Abstract P82: Implementation Of New Resuscitation Guidelines Takes One-and-a-half Year

Circulation ◽

10.1161/circ.118.suppl_18.s_1463 ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Jocelyn Berdowski ◽

Andra Schmohl ◽

Rudolph W Koster

Keyword(s):

Cardiac Arrest ◽

World Wide ◽

Prospective Observational Study ◽

Spontaneous Circulation ◽

Chest Compressions ◽

Return Of Spontaneous Circulation ◽

Resuscitation Guidelines ◽

Rhythm Analysis ◽

New Guidelines ◽

Hospital Cardiac Arrest

Objective- In November 2005, updated resuscitation guidelines were introduced world-wide, and will be revised again in 2010. This study aims to determine how long it takes to implement new guidelines. Methods- This was a prospective observational study. From July 2005 to January 2008, we included all patients with a non traumatic out-of-hospital cardiac arrest. Ambulance paramedics sent all continuous ECG registrations with impedance signal by modem. We excluded ECGs from patients with Return Of Spontaneous Circulation at arrival, incomplete ECG registrations, ECGs with technical deficits or with continuous chest compressions. The same guidelines needed to be used in over 75% of the registration time in order to be labeled. We classified ECGs as guidelines 2000 if the c:v ratio was 15:2, shock blocks were present and there was rhythm analysis after each shock; guidelines 2005 if the c:v ratio was 30:2, a single shock protocol was used and chest compressions was immediately resumed after shock or rhythm analysis in a no shock scenario. We accepted 10% deviations in the amount of compressions (13–17 for 2000 guidelines, 27–33 for 2005). Results- Of the 1703 analyzable ECGs, we classified 827 (48.6%) as guidelines 2000 and 624 (36.6%) as guidelines 2005. In the remaining 252 ECGs (14.8%) 31 used guidelines 1992, 137 applied guidelines 2000 with c:v ratio of 30:2 and 84 did not show distinguishable guideline usage. Since the introduction in November 2005, it took 17 months to apply new guidelines in over 80% of the cases (figure 1 ). Conclusion- Guideline changes are slowly implemented by professionals. This needs to be taken in consideration when new guideline revisions are considered.

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Letter by Shiyovich et al Regarding Article, “Resumption of Chest Compressions After Successful Defibrillation and Risk for Recurrence of Ventricular Fibrillation in Out-of-Hospital Cardiac Arrest”

Circulation Arrhythmia and Electrophysiology ◽

10.1161/circep.114.002333 ◽

2014 ◽

Vol 7 (6) ◽

pp. 1277-1277

Author(s):

Arthur Shiyovich ◽

Alexander Gerovich ◽

Amos Katz

Keyword(s):

Cardiac Arrest ◽

Ventricular Fibrillation ◽

Chest Compressions ◽

Hospital Cardiac Arrest

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Does bystander-initiated chest compressions-only result in better patient outcome than full cardiopulmonary resuscitation (CPR) for out-of-hospital cardiac arrest? Unexpected result from a post-hoc analysis of the DEFI 2005 Trial

Resuscitation ◽

10.1016/j.resuscitation.2010.10.010 ◽

2011 ◽

Vol 82 (1) ◽

pp. 130-131 ◽

Cited By ~ 1

Author(s):

Daniel Jost ◽

Descatha Alexis ◽

Isabelle Banville ◽

Catherine Verret ◽

Jean Pierre Carpentier

Keyword(s):

Patient Outcome ◽

Cardiac Arrest ◽

Cardiopulmonary Resuscitation ◽

Unexpected Result ◽

Chest Compressions ◽

Post Hoc Analysis ◽

Post Hoc ◽

Hospital Cardiac Arrest

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Leakage, Drag Power and Rotordynamic Force Coefficients of an Air in Oil (Wet) Annular Seal

Volume 7A: Structures and Dynamics ◽

10.1115/gt2017-63254 ◽

2017 ◽

Author(s):

Luis San Andrés ◽

Xueliang Lu

Keyword(s):

Test Data ◽

Volume Fraction ◽

Damping Coefficient ◽

Liquid Volume ◽

Pure Liquid ◽

Test Results ◽

Liquid Volume Fraction ◽

Force Coefficients ◽

Damping Coefficients ◽

Annular Seal

Wet gas compression systems and multiphase pumps are enabling technologies for the deep sea oil and gas industry. This extreme environment determines both machine types have to handle mixtures with a gas in liquid volume fraction (GVF) varying over a wide range (0 to 1). The gas (or liquid) content affects the system pumping (or compression) efficiency and reliability, and places a penalty in leakage and rotordynamic performance in secondary flow components, namely seals. In 2015, tests were conducted with a short length smooth surface annular seal (L/D = 0.36, radial clearance = 0.127 mm) operating with an oil in air mixture whose liquid volume fraction (LVF) varied to 4%. The test results with a stationary journal show the dramatic effect of a few droplets of liquid on the production of large damping coefficients. This paper presents further measurements and predictions of leakage, drag power, and rotordynamic force coefficients conducted with the same test seal and a rotating journal. The seal is supplied with a mixture (air in ISO VG 10 oil), varying from a pure liquid to an inlet GVF = 0.9 (mostly gas), a typical range in multiphase pumps. For operation with a supply pressure (Ps) up to 3.5 bar (a), discharge pressure (Pa) = 1 bar (a), and various shaft speed (Ω) to 3.5 krpm (ΩR = 23.3 m/s), the flow is laminar with either a pure oil or a mixture. As the inlet GVF increases to 0.9 the mass flow rate and drag power decrease monotonically by 25% and 85% when compared to the pure liquid case, respectively. For operation with Ps = 2.5 bar (a) and Ω to 3.5 krpm, dynamic load tests with frequency 0 < ω < 110 Hz are conducted to procure rotordynamic force coefficients. A direct stiffness (K), an added mass (M) and a viscous damping coefficient (C) represent well the seal lubricated with a pure oil. For tests with a mixture (GVFmax = 0.9), the seal dynamic complex stiffness Re(H) increases with whirl frequency (ω); that is, Re(H) differs from (K-ω2M). Both the seal cross coupled stiffnesses (KXY and −KYX) and direct damping coefficients (CXX and CYY) decrease by approximately 75% as the inlet GVF increases to 0.9. The finding reveals that the frequency at which the effective damping coefficient (CXXeff = CXX-KXY/ω) changes from negative to positive (i.e., a crossover frequency) drops from 50% of the rotor speed (ω = 1/2 Ω) for a seal with pure oil to a lesser magnitude for operation with a mixture. Predictions for leakage and drag power based on a homogeneous bulk flow model match well the test data for operation with inlet GVF up to 0.9. Predicted force coefficients correlate well with the test data for mixtures with GVF up to 0.6. For a mixture with a larger GVF, the model under predicts the direct damping coefficients by as much as 40%. The tests also reveal the appearance of a self-excited seal motion with a low frequency; its amplitude and broad band frequency (centered at around ∼12 Hz) persist and increase as the gas content in the mixture increase. The test results show that an accurate quantification of wet seals dynamic force response is necessary for the design of robust subsea flow assurance systems.

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