Non-invasive Cardiovascular Monitoring Research Articles

Cardiovascular Disease and Sleep Disordered Breathing: Are Children Vulnerable?

Cardiovascular Disease and Sleep Disordered Breathing: Are Children Vulnerable?

Blind System Identification of Noncoprime Multichannel Systems and Its Application to Noninvasive Cardiovascular Monitoring

Multichannel blind system identification (MBSI) is a technique for estimating both an unknown input and unknown channel dynamics from outputs measured at different points of the system. MBSI is a powerful tool particularly for the identification and estimation of dynamical systems in which a sensor, for measuring the input, is difficult to place. MBSI algorithms, however, are not applicable unless the transfer functions of individual channels are coprime, i.e., sharing no common dynamics among the channels. This paper presents a MBSI method, called intermediate input identification (IIID), applicable to multichannel, noncoprime systems containing common dynamics. A variable is introduced to split the original multichannel system into coprime multichannel subsystems and the one consisting of common dynamics. A modified MBSI method is used for identifying the coprime distinct channel dynamics, while the common dynamics is identified based on its unforced response. Identifiability conditions using linear complexity are obtained for both known and unknown model structures. Uniqueness and other properties of the solution are examined. The IIID method is then applied to noninvasive monitoring of the cardiovascular system. The arterial network is modeled as a multichannel system where the blood flow generated by the left ventricle is the input and pressure profiles measured at different branches of the artery, e.g., brachial, carotid, and femoral arteries, are the outputs. While the direct measurement of the input requires a catheter to be inserted into the heart, the IIID method does not need invasive catheterization. It would allow us to estimate both the wave form of the input flow and the arterial channel dynamics from outputs obtained with noninvasive sensors placed at different branches of the arterial network. Numerical examples and simulations verify the major theoretical results and the feasibility of the method.

Non-invasive beat-to-beat blood pressure monitoring: new developments.

Continuous blood pressure monitoring is an essential prerequisite for any study on blood pressure variability. Invasive procedures are no longer acceptable for research projects in a clinical setting, and recently developed devices able to record blood pressure on a beat-by-beat basis in a non-invasive fashion may represent valuable alternative tools. This article will briefly review the available information on the most recent advances in this field. It will focus on further developments of the original technology for finger blood pressure monitoring introduced by Penáz, as well as on newer devices that have been proposed over the last few years for non-invasive cardiovascular monitoring both in research and in clinical studies.

Atlas of Cardiovascular Monitoring.

Assistant Professor, Cardiothoracic Anesthesiology and Critical Care MedicineDepartment of AnesthesiologyWake Forest University School of MedicineMedical Center BoulevardWinston-Salem, North Carolina 27157-1009pbrath@wfubmc.eduAtlas of Cardiovascular Monitoring.By Jonathan B. Mark. New York, Churchill Livingstone, 1998. Pages: 362. Price: $79.00. Accurate integration and interpretation of cardiovascular monitoring data are paramount to proper care of patients. However, this standard is not always met, as is evidenced by numerous studies during the past decade or so that question the safety and effectiveness of invasive hemodynamic monitoring. Whether this deficiency is caused by the monitor itself, improper usage, or inadequate education is open for debate, but the Atlas of Cardiovascular Monitoring by Jonathan Mark goes a long way toward combating the problem of inadequate education.The Atlas of Cardiovascular Monitoring consists of 20 relatively concise chapters, each followed by extensive examples of various tracings, waveforms, and diagrams that discuss invasive and noninvasive cardiovascular monitoring. The text is well-written, accurate, and thorough without being oppressive, which allows for quick review when needed. The strength of this book, however, is in the diagrams. The diagrams are clear and well-captioned enough to stand on their own, and complement the text. They extensively show normal physiologic, diseased, and artifactual states that are frequently (and infrequently) seen during the care of patients in both the operating room and the intensive care unit. The diagrams emphasize, as is stressed and repeated throughout the entire book, the more accurate picture seen when various monitoring methods are integrated together.The first two chapters discuss general definitions of monitoring and waveform interpretation and its relation to the cardiac cycle. Chapters 3–6 discuss the basic waveforms found when floating a pulmonary artery catheter, identification and interpretation of the wedge pressure, artifacts encountered and how to recognize them, and the prediction of left ventricular end-diastolic pressure in both normal and diseased states. The next three chapters discuss invasive and noninvasive arterial blood pressure measurement and interpretation and thoroughly explain the technical aspects of monitoring systems, damping coefficients, and the like. The next two chapters discuss basic electrocardiology (lead placement, systems, and selection) and electrocardiographic detection of myocardial ischemia, including limitations and artifacts. The next three chapters (12–14) integrate information discussed previously to combine electrocardiographic and hemodynamic data for more accurate detection of myocardial ischemia, heart rate, and heart rhythm. The final six chapters focus on pressure–volume relations, interactions between the respiratory and circulatory systems, and various pathophysiologic states, including valvular heart disease, pericardial disease, changes during cardiopulmonary bypass, and proper interpretation of intraaortic balloon counterpulsation data.The Atlas of Cardiovascular Monitoring is one of those books that should be on all bookshelves. It is applicable to all levels of training and is appropriate for anesthesiologists, intensivists, cardiologists, and surgeons who rely on cardiovascular monitoring for diagnosis and guidance of therapy. At $79.00, it is reasonably priced (especially considering the information contained within), and it is of reasonable size to fit in my briefcase along with my laptop and go from the office to the operating room to the intensive care unit and home, without wearing me down.

The effects of exposure to moderate altitude on cardiovascular autonomic function in normal subjects.

Cardiovascular responses to altitude have been studied on well-trained young subjects, generally at high altitudes (>4000 m). Less known are the effects of exposure to lower altitudes, easily reached by the general population. The aim of the study was to evaluate the effects of exposure to a moderate altitude (2950 m) on heart rate (HR), blood pressure (BP) profile, and cardiovascular autonomic function, and their correlation with hemoglobin oxygen saturation (HbO2S), in untrained subjects of a wide age range. Twenty-seven healthy normotensive subjects (age range 6-83; 8 children, 9 adults, and 10 elderly subjects) underwent a battery of noninvasive cardiovascular reflex tests and 24-h ambulatory BP monitoring. Corrected QT interval was also calculated. HbO2S was measured with a transcutaneous oxymeter. All measurements were performed at about 200 m (s.l.) and repeated at 2950 m. 24-h HR and systolic/diastolic BP mean values increased at 2950 m in children (% change respectively: 6.4 +/- 6.4, p<0.05; 6.5 +/- 4.0/13.5 +/- 6.9, p < 0.05), adults (4.9 +/- 8.1, NS; 6.0 +/- 5.1/8.1 +/- 5.8, p < 0.05), and elderly subjects (7.2 +/- 4.8, p < 0.05; 5.1 +/- 2.3/2.8 +/- 4.1, p < 0.05 for systolic BP only). Standard deviation of BP mean values increased during night-time in the adult group (p < 0.05). All subjects scored normal cardiovascular test results and no differences were observed after exposure to 2950m, at both 1 hour and 24 hours from arrival. After exposure to altitude, HbO2S decreased significantly in the three groups, both on arrival and after 24 hours. No correlation was found between changes in HbO2S and BP/HR responses, and cardiovascular test results. In conclusion, exposure to moderate altitudes, easily and often reached by the general population, causes a small but significant increase in BP and HR in healthy untrained subjects of a wide age range (6-83 years). Some physiological factors (eg, lower environmental temperature and lifestyle modification) together with hypoxia, possibly more than altered cardiovascular reactivity, seem responsible for this cardiovascular change. In terms of end-organ damage, the clinical relevance of this increase in BP and BP variability for repeated exposure is not known.

Book Review: Non-Invasive Cardiovascular Monitoring.

Book Review: Non-Invasive Cardiovascular Monitoring.

Book Review: Non-Invasive Cardiovascular Monitoring

Book Review: Non-Invasive Cardiovascular Monitoring

A Manual for Non-invasive Cardiovascular Monitoring

A Manual for Non-invasive Cardiovascular Monitoring

Effects of acute intravenous cocaine on cardiovascular function, human learning, and performance in cocaine addicts

Continuous non-invasive cardiovascular monitoring in eight healthy cocaine addicts receiving intravenous cocaine (0.325 mg/kg or 0.650 mg/kg) or placebo in double-blind, randomized, cross-over fashion demonstrated significant dose-dependent increases in pulse and mean arterial pressure following cocaine. Pulse and mean arterial pressure peaked 5 min post-cocaine injection and maximal response was sustained for a further 15 min and 35 min afterwards, respectively. Cocaine administration had no significant effect on peripheral oxygen saturation, and no clinically significant abnormalities of rhythm or conduction were seen on the electrocardiogram. These doses and method of single-dose intravenous cocaine administration, and our procedures for cardiovascular monitoring, appear relatively safe for laboratory studies of healthy cocaine addicts with no pre-existing cardiovascular disease. In addition, cocaine-taking (0.325 mg/kg i.v. and 0.650 mg/kg i.v.) was associated with enhanced attention (i.e. increased numbers of correct responses on the Rapid Visual Information Processing Task), but the trend towards reduced reaction time did not achieve statistical significance. Cocaine-taking resulted in a small but statistically insignificant improvement in learning on the Digit Symbol Substitution Task. These results suggest that cocaine-taking in rested subjects is associated with some cognitive enhancement.

Non-invasive Cardiovascular Monitoring

Non-invasive Cardiovascular Monitoring

Dysvascular Amputee Rehabilitation

Recognition of cardiac problems and their impact on the treatment of dysvascular amputees is important during rehabilitation because the energy demands and cardiac work loads of functional activities are substantially greater when performed by persons with amputation than when performed by control subjects. For this reason, monitoring the cardiovascular response to therapeutic exercise might be expected to enhance the medical and rehabilitative management of dysvascular amputees. In the present study, 31 amputees with peripheral vascular disease underwent continuous noninvasive dynamic cardiovascular monitoring during an initial physical therapy session. The sample had a mean age of 65 yr. There were 20 females. Twenty patients had unilateral below knee amputation. Fifty-two percent had a preamputation history of cardiac disease and six experienced major cardiovascular complications during rehabilitation. After a mean acute hospitalization of 20 days and a mean rehabilitation stay of 36 days, 11 patients were walking independently and 25 were discharged to home. During the monitored physical therapy session, patients achieved a mean maximum heart rate of 113 beats/min, mean maximum blood pressure of 159/81, mean maximum rate-pressure product of 14,546, and mean percent of age-predicted maximal heart rate of 73%. Seventeen (55%) patients demonstrated abnormalities during the monitored session, four of whom had no prior history of heart disease. These changes consisted predominantly of ST-T segment abnormalities, but also included exercise-induced arrhythmias and decreases in blood pressure. Patients with a history of heart disease demonstrated significantly more abnormalities during the monitored session than did those without a history of heart disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Non-invasive Cardiovascular Monitoring

Non-invasive Cardiovascular Monitoring

Noninvasive Clinical lnvestigation of the Cardiovascular System in the Critacaflly Ill

An understanding of fundamental principles of various modes of noninvasive cardiovascular monitoring is important in the investigation and management of acute cardiac illnesses found in the critically ill. The clinical application of electrocardiography, radiology, echocardiography, and nuclear medicine will be discussed as it applies to investigation and management of the cardiovascular system in these patients.