A New Paradigm for Human Resuscitation Research Using Intelligent Devices

Objectives: To develop new methods for studying correlations between the performance and outcome of resuscitation efforts in real-world clinical settings using data recorded by automatic devices such as automatic external defibrillators (AEDs), and to explore effects of shock timing and chest compression depth in the field. Methods: In 695 records of AED use in the pre-hospital setting, continuous compression data were recorded using AEDs capable of measuring sternal motion during compressions, together with timing of delivered shocks and the electrocardiogram. In patients who received at least one shock, putative return of spontaneous circulation (P-ROSC) was defined as a regular, narrow complex electrical rhythm \u3e 40 beats/min with no evidence of chest compressions at the end of the recorded data stream. Transient return of spontaneous circulation (t-ROSC) was defined as the presence of a post-shock organized rhythm \u3e 40 beats/min within 60 seconds, and sustained 30 seconds. 2x2 contingency tables were constructed to examine the association between these outcomes and dichotomized time of shock delivery or chest compression depth, using the Mood median test for statistical significance. Results: The probability of P-ROSC for first shocks delivered \u3c 50 seconds (the median time) after the start of resuscitation was 23%, versus 11% for first shocks \u3e 50 seconds (p=0.028, one tailed). Similarly, the probability of t-ROSC for shorter times to shock was 29%, compared to the 15% for delayed first shocks (p=0.016). For shocks occurring \u3e3 minutes after initiation of rescue attempts, the probability of t-ROSC with pre-shock average compression depth \u3e 5 cm was more than double that with compression depth \u3c 5 cm (17.7% vs. 8.3%, p=0.028). For shocks \u3e5 minutes the effect of deeper compressions increased (23.4% vs. 8.2%, p=0.008). Conclusions: Much can be learned from analysis of performance data automatically recorded by modern resuscitation devices. Use of the Mood median test of association proved to be sensitive, valid, distribution independent, noise-resistant, and also resistant to biases introduced by the inclusion of hopeless cases. Efforts to shorten the time to delivery of the first shock and to encourage deeper chest compressions after the first shock are likely to improve resuscitation success. Such refinements can be effective even after an unknown period of preceding downtime

Detection of spontaneous pulse using the acceleration signals acquired from CPR feedback sensor in a porcine model of cardiac arrest.

Reliable detection of return of spontaneous circulation with minimal interruptions of chest compressions is part of high-quality cardiopulmonary resuscitation (CPR) and routinely done by checking pulsation of carotid arteries. However, manual palpation was time-consuming and unreliable even if performed by expert clinicians. Therefore, automated accurate pulse detection with minimal interruptions of chest compression is highly desirable during cardiac arrest especially in out-of-hospital settings.To investigate whether the acceleration (ACC) signals acquired from accelerometer-based CPR feedback sensor can be used to distinguish perfusing rhythm (PR) from pulseless electrical activity (PEA) in a porcine model of cardiac arrest.Cardiac arrest was induced in 49 male adult pigs. ECG, arterial blood pressure (ABP) and ACC waveforms were simultaneously recorded during CPR. 3-second segments containing compression-free signals during chest compression pauses were extracted and only those segments with organized rhythm were used for analysis. PR was defined as systolic arterial pressure >60 mmHg and pulse pressure >10 mmHg, while PEA was defined as an organized rhythm that does not meet the above criteria for PR. Peak correlation coefficient (CCp) of the cross-correlation function between pre-processed ECG and ACC, was used to discriminate PR and PEA.63 PR and 153 PEA were identified from the total of 1025 extracted segments. CCp was significantly higher for PR as compared to PEA (0.440±0.176 vs. 0.067±0.042, p<0.01) and highly correlated with ABP (r = 0.848, p<0.001). The area under the receiver operating characteristic curve, sensitivity, specificity and accuracy were 0.965, 93.6%, 97.5% and 96.7% for the ACC-based automatic spontaneous pulse detection.In this animal model, the ACC signals acquired from an accelerometer-based CPR feedback sensor can be used to detect the presence of spontaneous pulse with high accuracy

Longitudinal Phase Space Improvement of a Continuous-Wave Photoinjector Toward X-ray Free-Electron Laser Application

The electron source still remains a major challenge for continuous-wave (CW) X-ray free-electron lasers (FELs). In this paper, we study the feasibility of an injection line based on a DC and superconducting radio-frequency (SRF) combined photocathode injector. We present a detailed investigation on the longitudinal phase space evolution of the electron beam along the injection line. We also analyze the main issues determining the high-order energy spread and current skewness. Based on the analysis, we propose to use a harmonic cavity as the buncher for the injection line. Simulation shows that an extracted electron beam with a normalized RMS emittance of 0.37 m, an RMS bunch length of 1.0 mm, a high-order RMS energy spread of 2.75 keV, and a current skewness of 0 can be obtained at the bunch charge of 100 pC. This study is meaningful to the design of the injection lines for short-wavelength CW FELs, including those based on normal-conducting very-high-frequency (VHF) guns or DC guns

Distinct Carbon and Nitrogen Metabolism of Two Contrasting Poplar Species in Response to Different N Supply Levels

Poplars have evolved various strategies to optimize acclimation responses to environmental conditions. However, how poplars balance growth and nitrogen deficiency remains to be elucidated. In the present study, changes in root development, carbon and nitrogen physiology, and the transcript abundance of associated genes were investigated in slow-growing Populus simonii (Ps) and fast-growing Populus euramericana (Pe) saplings treated with low, medium, and high nitrogen supply. The slow-growing Ps showed a flourishing system, higher &delta;15N, accelerated C export, lower N uptake and assimilation, and less sensitive transcriptional regulation in response to low N supply. The slow-growing Ps also had greater resistance to N deficiency due to the transport of photosynthate to the roots and the stimulation of root development, which allows survival. To support its rapid metabolism and growth, compared with the slow-growing Ps, the fast-growing Pe showed greater root development, C/N uptake and assimilation capacity, and more responsive transcriptional regulation with greater N supply. These data suggest that poplars can differentially manage C/N metabolism and photosynthate allocation under different N supply conditions

A comparison of mean arterial pressure (MAP), peak correlation coefficient (CCp) and heart rate (HR) between segments of pulseless electrical activity (PEA) and perfusing rhythm (PR) during chest compression pauses.

<p>A comparison of mean arterial pressure (MAP), peak correlation coefficient (CCp) and heart rate (HR) between segments of pulseless electrical activity (PEA) and perfusing rhythm (PR) during chest compression pauses.</p

Illustration of ECG, arterial blood pressure (ABP) and acceleration (ACC) signals recorded during cardiopulmonary resuscitation and segments extracted for pulseless electrical activity and perfusing rhythm discrimination.

<p>Illustration of ECG, arterial blood pressure (ABP) and acceleration (ACC) signals recorded during cardiopulmonary resuscitation and segments extracted for pulseless electrical activity and perfusing rhythm discrimination.</p

Spontaneous pulse detection based on cross-correlation function between ECG and acceleration (ACC) signals.

<p>Spontaneous pulse detection based on cross-correlation function between ECG and acceleration (ACC) signals.</p

The relationship between peak correlation coefficient (CCp) of cross-correlation function and mean arterial pressure (MAP).

<p>* and o represent pulseless electrical activity and perfusing rhythm respectively.</p