Biomedical subjects

A Koulouris

Publications and source records attributed to A Koulouris.

4 recordsLinked to original sources

PubMed2000

A decentralized multichannel length transformation algorithm and its parallel implementation for real-time ECG monitoring.

Multichannel algorithms have been developed for more accurate analysis of electrocardiograms (ECGs). Their benefit is the ability to use the information contained in all simultaneously acquired channels. In this paper we present a multichannel version of a nonsyntactic algorithm, based on length transformation. The proposed algorithm uses a decentralized schema for combining the results derived from each individual lead, instead of a global/centralized one (a spatial vector approach). Its performance was evaluated using the CSE database and real ECGs acquired by a 12-lead cardiograph. The results are also compared with previous-single-channel and multichannel-versions of the algorithm, showing a better performance. Since a multichannel algorithm is always a time-consuming task, it is rarely used in real-time monitoring systems. Motivated by this observation, we designed a parallel implementation of the proposed algorithm and tested its ability to be used in such systems.

Algorithms↗

PubMed1996

ECG handling on a telemedicine platform.

In this paper we present the principles of a new platform developed for handling ECG signals in a telemedicine setting. We focus on three basic services: an ECG file management system (acquisition, storage, transmission); ECG-oriented teleconferencing; and realtime transmission of ECGs over the telephone network. This work has been carried out in the context of national and EU-sponsored projects. Its main purpose was to help patients from remote or isolated areas, like small islands, with insufficient health-care services, to get appropriate and experienced medical care directly from large central hospitals. We present the design and the basic operations of the ECG handling system.

Cardiovascular Diseases↗

PubMed1992

Development of thyrotropin circadian rhythm in infancy.

Normal children and adults show a similar pattern of diurnal variation of TSH secretion with lower values at 1100 h and higher around 2300 h. The purpose of this study was to investigate the age of appearance of TSH circadian rhythm. In 57 fullterm infants 0-6 months old and in 37 premature infants 1-4 weeks old TSH was measured at 1030, 1100, 1130 h and 2230, 2300, and 2330 h. No diurnal rhythm was detected in both premature and fullterm infants less than 4 weeks of life. After the first month of life a significant difference between AM and PM values was observed in fullterm infants. In infants 1-2 months old mean +/- SEM AM and PM values were 2.8 +/- 0.2 and 3.5 +/- 0.4 mU/L, respectively (P less than 0.025), in infants 3-4 months old 3.0 +/- 0.6 and 4.1 +/- 0.8 (P less than 0.01) and in infants 5-6 months old 1.8 +/- 0.2 and 2.6 +/- 0.3 (P less than 0.0005). These data clearly indicate that the development of TSH circadian rhythm starts after the first month of life.

Circadian Rhythm↗

PubMed1991

A simple stress test for the evaluation of hypothalamic-pituitary-adrenal axis during the first 6 months of life.

In 33 normal infants, divided into 3 age groups (less than 1 month, 1-3 months, and 3-6 months) plasma cortisol was measured at 2230, 2300, and 2330 h. Baseline plasma cortisol at 2230 h. was, as expected, low in all infants, with mean +/- SEM values of 41 +/- 5, 72 +/- 14, and 97 +/- 17 nmol/L in each group, respectively. Thirty and 60 min after the painful stimulus of the venipuncture, plasma cortisol increased significantly (P less than 0.0005), reaching a maximum increase up to 458 +/- 50, 392 +/- 66, and 455 +/- 97 nmol/L in each age group, respectively. We conclude that in these infants the hypothalamic-pituitary-adrenal axis was functionally intact and responded to the painful stimulus of the venipuncture by a significant increase in plasma cortisol. This test may be used as a simple procedure for the evaluation of the integrity of the hypothalamic-pituitary-adrenal axis without the administration of pharmacological agents. Its usefulness, however, should be validated with patients having a disorder of the system.

Adrenal Glands↗