Biomedical subjects

Shannon Peck

Publications and source records attributed to Shannon Peck.

3 recordsLinked to original sources

PubMed2005

Search for disease-specific cardiovascular reactivity patterns: developing the methodology.

Aberrations of CVR (cardiovascular reactivity), an expression of autonomic function, lack specificity for a particular disorder. Recently, a CVR pattern particular to chronic fatigue syndrome has been observed. In the present study, we aimed to develop methodologies for assessing disease-specific CVR patterns. As a prototype, a population of 50 consecutive patients with FMF (familial Mediterranean fever) was studied and compared with control populations. A 10 min supine/30 min head-up tilt test with recording of the heart rate and blood pressure or the pulse transit time was performed. Five studies were conducted applying different methods. In each study, statistical analysis identified independent predictors of CVR in FMF. Based on regression coefficients of these predictors, a linear DS (discriminant score) was computed for every subject. Each study established an equation to assess CVR, calculate DS for FMF and determine the sensitivity and specificity of the DS cut-off. In each of the five studies, abnormal CVR was observed in FMF patients. The best accuracy (88% sensitivity and 90.1% specificity for FMF) was obtained by a method based on beat-to-beat heart rate and pulse transit time recordings. Data was processed by fractal and recurrence quantitative analysis with recordings in FMF patients compared with a mixed control population. Identification of disease-specific CVR patterns was possible with the methodologies described in the present study. In FMF, disease-specific CVR may be explained by the interplay between neuroendocrine loops specific to FMF with cardiovascular homoeostatic mechanisms. Recognition of disease-specific CVR patterns may advance the understanding of homoeostatic mechanisms and have implications in clinical practice.

Adult↗

PubMed2005

Cardiovascular reactivity in fibromyalgia: evidence for pathogenic heterogeneity.

OBJECTIVE: To evaluate disease-specific cardiovascular reactivity patterns in patients with fibromyalgia (FM) using a recently described method called fractal and recurrence analysis score (FRAS). METHODS: The study group included 30 women with FM, average age 46.7 years (SD 7.03). An age matched group of 30 women with other rheumatic disorders or having a dysautonomic background [chronic fatigue syndrome (CFS), non-CFS fatigue, neurally mediated syncope, and psoriatic arthritis (PsA)] served as controls. Subjects were evaluated with a head-up tilt test with beat-to-beat recording of the heart rate (HR) and pulse transit time. A 10-minute supine phase was followed by 600 cardiac cycles recorded on tilt. Data were processed by recurrence plot and fractal analysis. Variables acting as independent predictors of the cardiovascular reactivity were identified in FM patients versus controls. RESULTS: No statistically significant differences were found between the groups by univariate analysis comparing 92 variables of cardiovascular reactivity in FM patients compared to controls. CONCLUSION: Study of cardiovascular reactivity utilizing a head-up tilt test and processing the data using the FRAS method did not reveal a specific FM-associated abnormality. Our data confirm studies that utilized other methodologies and reached similar conclusions. Patients with FM represent a heterogenous group with respect to their pattern of cardiovascular reactivity.

Arthritis, Psoriatic↗

PubMed2004

Pulse transit time by R-wave-gated infrared photoplethysmography: review of the literature and personal experience.

OBJECTIVE: Pulse transit time (PTT) is the time it takes a pulse wave to travel between two arterial sites. A rela tively short PTT is observed with high blood pressure (BP), aging, arteriosclerosis and diabetes mellitus. Most methods used for measuring the PTT are cumbersome and expensive. In contrast, the interval between the peak of the R-wave on the electrocardiogram and the onset of the corresponding pulse in the finger pad measured by photoplethysmography can be easily measured. We review herein the literature and impart the experience at our institution on clinical applications of R-wave-gated photo-plethysmography (RWPP) as measurement of PTT. METHODS: The MEDLINE data base on clinical applications of RWPP was reviewed. In addition, studies performed in the author's institution are presented. RESULTS: When used as a surrogate for beat-to-beat BP monitoring, RWPP did not meet the level of accuracy required for medical practice (two studies). RWPP produced accurate and reproducible signals when utilized as a surrogate for intra-thoracic pressure changes in obstructive sleep apnea, as well as BP arousals which accompany central sleep apnea (five studies). In estimation of arterial stiffness, RWPP was unsatisfactory (one study). In assessment of cardiovascular reactivity, abnormal values of RWPP were noted in autonomic failure (one study), while disease-specific reactivity patterns were identified utilizing a method involving RWPP (two studies). CONCLUSIONS: In clinical practice, sleep-apnea may be accurately monitored by RWPP. RWPP seems to reflect autonomic influences and may be particularly well-suited for the study of vascular reactivity. Thus, further descriptions of disease-specific cardiovascular reactivity patterns may be possible with techniques based on RWPP. Other clinical uses of RWPP are investigational.

Blood Pressure↗