Thomas Heldt

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W e report the establishment of the Multiparameter Intelligent Monitoring in Intensive Care II (MIMIC-II) research database that is notable for four factors: it is publicly and freely available to other research organizations upon request; it encompasses a diverse population of intensive care unit (ICU) patients; it contains high temporal resolution data,(More)
OBJECTIVE We sought to develop an intensive care unit research database applying automated techniques to aggregate high-resolution diagnostic and therapeutic data from a large, diverse population of adult intensive care unit patients. This freely available database is intended to support epidemiologic research in critical care medicine and serve as a(More)
The objective of this study is to develop a model of the cardiovascular system capable of simulating the short-term (< or = 5 min) transient and steady-state hemodynamic responses to head-up tilt and lower body negative pressure. The model consists of a closed-loop lumped-parameter representation of the circulation connected to set-point models of the(More)
Time-varying elastance models have been used extensively in the past to simulate the pulsatile nature of cardiovascular waveforms. Frequently, however, one is interested in dynamics that occur over longer time scales, in which case a detailed simulation of each cardiac contraction becomes computationally burdensome. In this paper, we apply circuit-averaging(More)
Intracranial pressure (ICP) is affected in many neurological conditions. Clinical measurement of pressure on the brain currently requires placing a probe in the cerebrospinal fluid compartment, the brain tissue, or other intracranial space. This invasiveness limits the measurement to critically ill patients. Because ICP is also clinically important in(More)
OBJECTIVE The value of different algorithms that estimate cardiac output (CO) by analysis of a peripheral arterial blood pressure (ABP) waveform has not been definitively identified. In this investigation, we developed a testing data set containing a large number of radial ABP waveform segments and contemporaneous reference CO by thermodilution(More)
Modern intensive care units (ICUs) employ an impressive array of technologically sophisticated instrumentation to provide detailed measurements of the pathophysiological state of each patient. Providing life support in the ICU is becoming an increasingly complex task, however, because of the growing volume of relevant data from clinical observations,(More)
To understand the sequence of hemodynamic events elicited by active (stand-up) and passive (head-up tilt, HUT) changes in posture, we monitored heart rate and arterial blood pressure continuously in ten healthy volunteers at rest, during rapid tilts (75 HUT over 2 secs), slow tilts (75 HUT over 50 secs), and stand tests. A marked initial transient drop in(More)
We describe a novel model-based approach to estimate cardiac output (CO) and total peripheral resistance (TPR) continuously from peripheral arterial blood pressure (ABP) waveforms. Our method exploits the intra-beat and inter-beat variability in ABP to estimate the lumped time constant of a beat-to-beat averaged Windkessel model of the arterial tree, from(More)
Circuit-based lumped parameter representations of the hemodynamic system are commonly used in teaching and research to analyze the system-level behavior of the circulation. While efficient numerical methods exist to solve the governing differential equations numerically, we present an analytical solution of a simplified hemodynamic model that is based on a(More)