Biomedical subjects

Agostinho Rosa

Publications and source records attributed to Agostinho Rosa.

6 recordsLinked to original sources

PubMed2006

Visual and automatic cyclic alternating pattern (CAP) scoring: inter-rater reliability study.

The classification of short duration events in the EEG during sleep, as the A stage of the cyclic alternating pattern (CAP) is a tedious and error prone task. The number of events under normal conditions is large (several hundreds), and it is necessary to mark the limits of the events with precision, otherwise the time sensitive classification of the CAP phases (A and B) and specially the scoring of different types of A phases will be compromised. The objective of this study is to verify the feasibility of visual CAP scoring with only one channel of EEG, the evaluation of the inter-scorer agreement in a variety of recordings, and the comparison of the visual scorings with a known automatic scoring system. Sixteen hours of one channel (C4-A1 or C3-A2) of NREM sleep were extracted from eight whole night recordings in European Data Format and presented to the different scorers. The average inter-scorer agreement for all scorers is above 70%, the pair wise inter-scorer agreement found was between 69% up to 77.5%. These values are similar to what has been reported in different type studies. The automatic scoring system has similar performance of the visual scorings. The study also has shown that it is possible to classify the CAP using only one channel of EEG.

Electroencephalography↗

PubMed2005

[Violent behavior during sleep].

Cases of violent behavior during sleep have been reported in the literature. However, the incidence of violent behavior during sleep is not known. One epidemiological study showed that approximately 2% of the general population, predominantly males, presented violent behavior while asleep. In the present study, the authors describe clinical and medico-legal aspects involved in violent behavior investigation. Violent behavior refers to self-injury or injury to another during sleep. It happens most frequently following partial awakening in the context of arousal disorders (parasomnias). The most frequently diagnosed sleep disorders are REM behavior disorder and somnambulism. Violent behavior might be precipitated by stress, use of alcohol or drugs, sleep deprivation or fever.

Adult↗

PubMed2005

Heart rate variability, sympathetic and vagal balance and EEG arousals in upper airway resistance and mild obstructive sleep apnea syndromes.

BACKGROUND AND PURPOSE: We questioned the role of respiratory events in obstructive sleep apnea syndrome (OSAS) and of upper airway resistance syndrome (UARS) on heart rate (HR) during sleep, paying specific attention to the termination of the abnormal breathing events and examining the presence of arousals or termination with only central nervous system (CNS) activation. PATIENTS AND METHODS: Twenty patients, 10 with UARS and 10 with mild OSAS, were studied. A nocturnal polysomnogram was performed including measurement of respiratory variables and pulse transit time (PTT). According to the presence or absence of a PTT event indicative of autonomic nervous system (ANS) activation, 148 events were extracted after having been randomly chosen in each represented sleep stage, with or without an electroencephalogram (EEG) arousal >1.5s. RR interval (RRI) in electrocardiogram (ECG) recordings, as well as heart rate variability, was calculated during 60 and 120s, respectively. Period amplitude analysis (PAA) was applied for RR-interval analysis, and fast Fourier transformation (FFT) was applied to perform HR variability analysis. RESULTS: Visually scored EEG arousal was significantly associated with an increase in sympathetic index of heart rate, while PTT was associated with a drop in parasympathetic index, after the respiratory events. Patients with mild OSAS presented persistently shorter RRI when compared to patients with UARS. The latter also exhibited a significant decrease in parasympathetic index (High Frequency (HF)) at the termination of a respiratory event. CONCLUSION: The HF component was only significantly decreased in patients with UARS, which indicates a predominant involvement of the parasympathetic tone in patients with UARS in comparison to those with OSAS.

Adult↗

PubMed2005

Cyclic alternating pattern in peripubertal children.

STUDY OBJECTIVES: The aim of this study is to complement the data on the expression and characteristics of cyclic alternating pattern (CAP) events in children, specifically in the peripubertal age group of 8 to 12 years and to analyze the association of CAP events with arousals. The study of CAP and arousal is a useful tool for assessing sleep instability and fragmentation in children. DESIGN: Descriptive study. PARTICIPANTS: Ten sex-matched healthy children, aged 8 to 12 years, underwent standard polysomnography after 1 adaptation night in the sleep laboratory. Sleep stages, CAP, and arousals were analyzed according to standard international rules. RESULTS: The mean CAP rate was 62.1% +/- 10.8% and the mean CAP cycle duration, 24.6 +/- 2.1 minutes. CAP A1 phase was the most numerous (85.5% +/- 3.9%), whereas the A2 phase was 9.1% +/- 4.7%, and the A3 phase as 5% +/- 2.3%, (P < .01). Differences between boys and girls were detected by analysis of variance, namely increases of phase A2 and A3 subtypes in girls (P < .001). Stronger phase A1 subtype expression in slow-wave sleep was verified in both sexes. Positive correlation between electroencephalogram arousals and the sum of phase A2 and A3 subtypes was also present. The overall CAP rate is higher in this age group than the rate previously reported in children aged 6 to 10 years (62.1% +/- 10.8% vs 33.4% +/- 5.3%). CONCLUSIONS: Our study provides normative data on CAP in children aged 8 to 12 years and indicates that age and Tanner stages must both be considered when investigating peripubertal children.

Child↗

PubMed2004

Gray-scale image enhancement as an automatic process driven by evolution.

Image enhancement is the task of applying certain transformations to an input image such as to obtain a visually more pleasant, more detailed, or less noisy output image. The transformation usually requires interpretation and feedback from a human evaluator of the output result image. Therefore, image enhancement is considered a difficult task when attempting to automate the analysis process and eliminate the human intervention. This paper introduces a new automatic image enhancement technique driven by an evolutionary optimization process. We propose a novel objective criterion for enhancement, and attempt finding the best image according to the respective criterion. Due to the high complexity of the enhancement criterion proposed, we employ an evolutionary algorithm (EA) as a global search strategy for the best enhancement. We compared our method with other automatic enhancement techniques, like contrast stretching and histogram equalization. Results obtained, both in terms of subjective and objective evaluation, show the superiority of our method.

Journal Article↗

PubMed2002

Sleep and EEG power spectrum in post encephalitis hypersomnia: a case report.

The nocturnal recordings of breathing, and sleep and daytime multiple sleep latency tests over the 5 year follow-up of a patient with post encephalitis hypersomnia are presented. EEG power spectrum analysis was performed on the last polysomnographic recording, and the results were compared with those obtained for a matched control subject. The patient presented initially a hypoventilation syndrome controlled by nasal bilevel positive pressure at night. The syndrome progressively improved, but daytime sleepiness stayed unchanged with limited help from stimulants. Fast Fourier transformation analysis of the last nocturnal recording demonstrates a decrease in absolute power for all frequency bands in all sleep stages, but a cyclical presence of the NREM/REM.

Journal Article↗