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A clinical method for monitoring cardiac output (CO) should be continuous, minimally invasive, and accurate. However, none of the conventional CO measurement methods possess all of these characteristics. On the other hand, peripheral arterial blood pressure (ABP) may be measured reliably and continuously with little or no invasiveness. We have developed a novel technique for continuously monitoring changes in CO by mathematical analysis of a peripheral ABP waveform. In contrast to the previous techniques, our technique analyzes the ABP waveform over time scales greater than a cardiac cycle in which the confounding effects of complex wave reflections are attenuated. The technique specifically analyzes 6-min intervals of ABP to estimate the pure exponential pressure decay that would eventually result if pulsatile activity abruptly ceased (i.e., after the high frequency wave reflections vanish). The technique then determines the time constant of this exponential decay, which equals the product of the total peripheral resistance and the nearly constant arterial compliance, and computes proportional CO via Ohm's law. To validate the technique, we performed six acute swine experiments in which peripheral ABP waveforms and aortic flow probe CO were simultaneously measured over a wide physiologic range. We report an overall CO error of 14.6%. Index Terms--Arterial blood pressure, arterial tree, cardiac output, distributed effects, hemodynamics, mathematical modeling, pulse contour analysis, system identification, wave reflections, Windkessel.

Background: Comparative morbidity after either sternotomy or non-resuscitative thoracotomy in penetrating cardiac injuries (PCI) is unknown. Methods: Retrospective review of adults with PCI who underwent either sternotomy or nonresuscitative thoracotomy using the National Trauma Data Bank 2007-2015. Since there is no unique International Classification of Diseases Procedure Coding System (ICD-PCS) codes assigned for resuscitative vs. non-resuscitative thoracotomy, and both procedures were coded as "thoracotomy", propensity score (PS) methods were applied to avoid inclusion of resuscitative thoracotomy. Results: Despite well PS matching on injury severity score the non-thoracotomy group compared to the sternotomy group had a significantly increased risk of mortality (30 percent vs 8 percent, p<0.0001). The morbidity differed as well--25 percent vs. 12 percent, p=0.0007. Conclusions: The differences in mortality in PCI patients who underwent non-resuscitative thoracotomy vs. sternotomy may be biased by unintentional inclusion of resuscitative thoracotomy. To accurately capture thoracotomy type, separate unique resuscitative and non-resuscitative thoracotomy procedure codes should be created in future revisions of the ICD codes. [ABSTRACT FROM AUTHOR]

This paper presents a novel method to identify the cardiovascular (CV) system using two distinct peripheral blood pressure (BP) signals. The method can characterize the distinct arterial path dynamics that shape each of the BP signals and recover the common central-flow signal fed to them. A Laguerre series data-compression technique is used to obtain a compact representation of the CV system, whose coefficients are identified using the multichannel blind system identification. A Laguerre model deconvolution algorithm is developed to stably recover the central-flow signal. Persistent excitation, model identifiability, and asymptotic variance are analyzed to quantify the method's validity and reliability, without using any direct measurement of central-flow input signal. Experimental results based on 7000 data segments obtained from nine swine subjects show that, for all the swine subjects under diverse physiologic conditions, the CV dynamics can be identified very reliably and the waveform of the central flow can be recovered stably from peripheral BP signals. [ABSTRACT FROM AUTHOR]

Background: Comparative morbidity after either sternotomy or non-resuscitative thoracotomy in penetrating cardiac injuries (PCI) is unknown., Methods: Retrospective review of adults with PCI who underwent either sternotomy or non-resuscitative thoracotomy using the National Trauma Data Bank 2007-2015. Since there is no unique International Classification of Diseases Procedure Coding System (ICD-PCS) codes assigned for resuscitative vs. non-resuscitative thoracotomy, and both procedures were coded as "thoracotomy", propensity score (PS) methods were applied to avoid inclusion of resuscitative thoracotomy., Results: Despite well PS matching on injury severity score the non-thoracotomy group compared to the sternotomy group had a significantly increased risk of mortality (30 percent vs 8 percent, p<0.0001). The morbidity differed as well-25 percent vs. 12 percent, p=0.0007., Conclusions: The differences in mortality in PCI patients who underwent non-resuscitative thoracotomy vs. sternotomy may be biased by unintentional inclusion of resuscitative thoracotomy. To accurately capture thoracotomy type, separate unique resuscitative and non-resuscitative thoracotomy procedure codes should be created in future revisions of the ICD PCS., (Copyright © 2021 by the American Health Information Management Association.)