The pulmonary artery catheter is routinely employed for hemodynamic monitoring of critically ill patients. This catheter permits the estimation of cardiac output (CO) via thermodilution and left heart filling pressure (i.e., left atrial pressure (LAP)) through pulmonary capillary wedge pressure (PCWP). However, these measurements are only obtained intermittently as an operator is required. On the other hand, pulmonary artery pressure (PAP) is measured continuously and automatically with the catheter. A few investigators have therefore proposed analysis techniques to continuously monitor CO from a PAP waveform. However, these techniques were not able to overcome the highly complex wave and inertial effects that corrupt PAP waveforms and were thus unsuccessful. Moreover, even though LAP is also a significant determinant of PAP, none of these techniques provided a means to monitor LAP. We have developed a one of a kind technique for continuously and automatically monitoring both CO and LAP by mathematical analysis of a PAP waveform. In contrast to all previous, related attempts, our technique analyzes the waveform over time scales greater than a cardiac cycle in which the complex wave and inertial effects cease to be a factor. We have conducted initial testing of the technique in nine intensive care unit (ICU) patients, and our results are in agreement with thermodilution and PCWP measurements. We propose further development and evaluation of the technique based on a growing database of ICU patients including hundreds of annotated pulmonary artery catheterization data sets.
Specific Aim 1 is to optimize the mathematical analysis technique. We will refine the technique by optimally incorporating the long time scale PAP information in the analysis.
Specific Aim 2 is to validate the technique with respect to the standard ICU measurements. We will statistically compare the CO and LAP estimated by the technique with thermodilution and PCWP over all, and under each, of the patient conditions (e.g., therapy, disease).
Specific Aim 3 is to compare the performance of the technique to all other competing analysis techniques. We will implement all competing PAP waveform analysis techniques, optimize their performance, and likewise comprehensively evaluate and compare them. Successful achievement of these specific aims may ultimately lead to continuous and automatic monitoring of CO and LAP in ICUs and operating and recovery rooms and thereby benefit the clinical management of those patients with indications for pulmonary artery catheterization. ? ?
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