Gonzalo César Gutiérrez-Tobal

• PhD
• PostDoc Position at University of Valladolid

The purpose of this study is to evaluate the usefulness of the boosting algorithm AdaBoost (AB) in the context of the sleep apnea-hypopnea syndrome (SAHS) diagnosis. We characterize SAHS in single-channel airflow (AF) signals from 317 subjects by the extraction of spectral and non-linear features. Relevancy and redundancy analyses are conducted thr...

Background: The vast majority of children around the world undergoing adenotonsillectomy for obstructive sleep apnea-hypopnea syndrome (OSA) are not objectively diagnosed with nocturnal polysomnography (NPSG) due to access availability and cost issues. Automated analysis of nocturnal oximetry (nSpO2), which is readily and globally available, could...

Complexity, costs, and waiting lists issues demand a simplified alternative for sleep apnea-hypopnea syndrome (SAHS) diagnosis. The blood oxygen saturation signal (SpO2) carries useful information about SAHS and can be easily acquired from overnight oximetry. In this study, SpO2 single-channel recordings from 320 subjects were obtained at patients’...

The ability of a cloud-driven Bluetooth oximetry-based algorithm to diagnose obstructive sleep apnoea syndrome (OSAS) was examined in habitually snoring children concurrently undergoing overnight polysomnography. Children clinically referred for overnight in-laboratory polysomnographic evaluation for suspected OSAS were simultaneously hooked to a B...

One major risk of paediatric sleep apnoea-hypopnoea syndrome (SAHS) is the development of cognitive impairments among affected children. Electroencephalography (EEG) is ordinarily used as part of polysomnography, the standard diagnostic test for SAHS. However, how SAHS changes overnight EEG, and its relationships with cognitive performance, remains...

Diabetic retinopathy (DR) is one of the leading causes of blindness globally. Several studies indicate that 90% of cases are preventable through early detection and appropriate treatment. Due to the increasing number of diabetic patients, the number of images that ophthalmologists have to manually analyze is becoming unaffordable. In this study, we...

Sleep spindles are microevents of the electroencephalogram (EEG) during sleep whose functional interpretation is not fully clear. To streamline the identification process and make it more replicable, multiple automatic detectors have been proposed in the literature. Among these methods, algorithms based on deep learning usually demonstrate superior...

Obstructive sleep apnea (OSA) in children is a prevalent and serious respiratory condition linked to cardiovascular morbidity. Polysomnography, the standard diagnostic approach, faces challenges in accessibility and complexity, leading to underdiagnosis. To simplify OSA diagnosis, deep learning (DL) algorithms have been developed using cardiac sign...

Deep-learning algorithms have been proposed to analyze overnight airflow (AF) and oximetry (SpO 2) signals to simplify the diagnosis of pediatric obstructive sleep apnea (OSA), but current algorithms are hardly interpretable. Explainable artificial intelligence (XAI) algorithms can clarify the models-derived predictions on these signals, enhancing...

La degeneración macular asociada a la edad (DMAE) es un trastorno que afecta a la mácula, una zona de la retina clave para la agudeza visual. La DMAE es una de las causas más frecuentes de ceguera en personas mayores de 60 años en los países desarrollados. Aunque se han propuesto tratamientos que frenan su desarrollo, su eficacia disminuye signific...

Background Obstructive sleep apnea (OSA) is a risk factor for metabolic syndrome (MetS) in adults, but its association in prepubertal children is still questionable due to the relatively limited cardiometabolic data available and the phenotypic heterogeneity. Objective To identify the role of OSA as a potential mediator of MetS in prepubertal chil...

The high prevalence of sleep apnea and the limitations of polysomnography have prompted the investigation of strategies aimed at automated diagnosis using a restricted number of physiological measures. This study aimed to demonstrate that thoracic (THO) and abdominal (ABD) movement signals are useful for accurately estimating the severity of sleep...

- Heart rate variability (HRV) is modulated by sleep stages and apneic events. Previous studies in children compared classical HRV parameters during sleep stages between obstructive sleep apnea (OSA) and controls. However, HRV-based characterization incorporating both sleep stages and apneic events has not been conducted. Furthermore, recently prop...

A growing number of studies have shown the strong relationship between sleep and different cognitive processes, especially those that involve memory consolidation. Traditionally, these processes were attributed to mechanisms related to the macroarchitecture of sleep, as sleep cycles or the duration of specific stages, such as the REM stage. More re...

The overnight polysomnography shows a range of drawbacks to diagnose obstructive sleep apnea (OSA) that have led to the search for artificial intelligence-based alternatives. Many classic machine learning methods have been already evaluated for this purpose. In this chapter, we show the main approaches found in the scientific literature along with...

Automated analysis of the blood oxygen saturation (SpO 2) signal from nocturnal oximetry has shown usefulness to simplify the diagnosis of obstructive sleep apnea (OSA), including the detection of respiratory events. However, the few preceding studies using SpO 2 recordings have focused on the automated detection of respiratory events versus normal...

Obstructive sleep apnea (OSA) is a multidi-mensional disease often underdiagnosed due to the complexity and unavailability of its standard diagnostic method: the polysomnography. Among the alternative abbreviated tests searching for a compromise between simplicity and accurateness, oximetry is probably the most popular. The blood oxygen saturation...

The airflow (AF) is a physiological signal involved in the overnight polysomnography (PSG) that reflects the respiratory activity. This signal is able to show the particularities of sleep apnea and is therefore used to define apneic events. In this regard, a growing number of studies have shown the usefulness of employing the overnight airflow as t...

Background Machine‐learning approaches have enabled promising results in efforts to simplify the diagnosis of pediatric obstructive sleep apnea (OSA). A comprehensive review and analysis of such studies increase the confidence level of practitioners and healthcare providers in the implementation of these methodologies in clinical practice. Objecti...

Previous studies have suggested that the typical slow oscillations (SO) characteristics during sleep could be modified in the presence of pediatric obstructive sleep apnea (OSA). Here, we evaluate whether these modifications are significant and if they may reflect cognitive deficits. We recorded the overnight electroencephalogram (EEG) of 294 pedia...

The gold standard approach to diagnose obstructive sleep apnea (OSA) in children is overnight in-lab polysomnography (PSG), which is labor-intensive for clinicians and onerous to healthcare systems and families. Simplification of PSG should enhance availability and comfort, and reduce complexity and waitlists. Airflow (AF) and oximetry (SpO2) signa...

Despite significant and meritorious research efforts over the last decades, the functions and evolutionary determinants of sleep remain one of the mysterious and relatively unexplored dimensions of physiology (Krueger et al, 2016). The recipe for deciphering such an attractive challenge in biology and medicine most probably includes ingredients suc...

Pediatric obstructive sleep apnea (OSA) is a prevalent disorder that disrupts sleep and is associated with neurocognitive and behavioral negative consequences, potentially hampering the development of children for years. However, its relationships with sleep electroencephalogram (EEG) have been scarcely investigated. Here, our main objective was to...

Overnight pulse oximetry has shown usefulness to simplify obstructive sleep apnea (OSA) diagnosis when combined with machine-learning approaches. However, the development and evaluation of a single model with ability to reach high diagnostic performance in both community-based non-referral and clinical referral cohorts are still pending. Since ense...

Sleep staging is of paramount importance in children with suspicion of pediatric obstructive sleep apnea (OSA). Complexity, cost, and intrusiveness of overnight polysomnography (PSG), the gold standard, have led to the search for alternative tests. In this sense, the photoplethysmography signal (PPG) carries useful information about the autonomous...

The author wishes to make the following correction to this paper [...]

Study Objectives Pediatric obstructive sleep apnea (OSA) affects cardiac autonomic regulation, altering heart rate variability (HRV). Although changes in classical HRV parameters occur after OSA treatment, they have not been evaluated as reporters of OSA resolution. Specific frequency bands (named BW1, BW2 and BWRes) have been recently identified i...

Pediatric obstructive sleep apnea (OSA) is a breathing disorder that alters heart rate variability (HRV) dynamics during sleep. HRV in children is commonly assessed through conventional spectral analysis. However, bispectral analysis provides both linearity and stationarity information and has not been applied to the assessment of HRV in pediatric...

Objective. Nested into slow oscillations (SOs) and modulated by their up-states, spindles are electrophysiological hallmarks of N2 sleep stage that present a complex hierarchical architecture. However, most studies have only described spindles in basic statistical terms, which were limited to the spindle itself without analyzing the characteristics...

This study focused on the automatic analysis of the airflow signal (AF) to aid in the diagnosis of pediatric obstructive sleep apnea (OSA). Thus, our aims were: (i) to characterize the overnight AF characteristics using discrete wavelet transform (DWT) approach, (ii) to evaluate its diagnostic utility, and (iii) to assess its complementarity with t...

Pediatric Obstructive Sleep Apnea (OSA) is a respiratory disease whose diagnosis is performed through overnight polysomnography (PSG). Since it is a complex, time-consuming, expensive, and labor-intensive test, simpler alternatives are being intensively sought. In this study, bispectral analysis of overnight airflow (AF) signal is proposed as a pot...

This study aims at assessing the usefulness of deep learning to enhance the diagnostic ability of oximetry in the context of automated detection of pediatric obstructive sleep apnea (OSA). A total of 3196 blood oxygen saturation (SpO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) signals fro...

Positional obstructive sleep apnea (POSA) is a major phenotype of sleep apnea. Supine-predominant positional patients are frequently characterized by milder symptoms and less comorbidity due to a lower age, body mass index, and overall apnea-hypopnea index. However, the bradycardia-tachycardia pattern during apneic events is known to be more severe...

En este estudio se evalúa la utilidad de una arquitectura deep learning basada en módulos Inception para mejorar la capacidad diagnóstica de la señal de saturación de oxígeno en sangre (SpO2) en la ayuda al diagnóstico de la apnea obstructiva del sueño (AOS) infantil. Estudios recientes demandan la aplicación de nuevas arquitecturas de deep learnin...

Este estudio se centra en el análisis automático de la señal de flujo aéreo monocanal (FA) para la ayuda en el diagnóstico de la Apnea Obstructiva del Sueño (AOS) infantil. En concreto, se ha evaluado la utilidad diagnóstica de las medidas extraídas de los diferentes niveles de descomposición obtenidos al aplicar la transformada wavelet discreta a...

El objetivo de este estudio fue evaluar la utilidad de la transformada wavelet de las señales de flujo aéreo (FA) y saturación de oxígeno en sangre (SpO2) para detectar la apnea obstructiva del sueño (AOS) infantil. Para ello, se emplearon las señales de 974 sujetos pediátricos con sospecha de padecer AOS, que se dividieron aleatoriamente en conjun...

Background: Classic spectral analysis of heart rate variability (HRV) in pediatric sleep apnea-hypopnea syndrome (SAHS) traditionally evaluates the very low frequency (VLF: 0-0.04 Hz), low frequency (LF: 0.04-0.15 Hz), and high frequency (HF: 0.15- 0.40 Hz) bands. However, specific SAHS-related frequency bands have not been explored. Methods: 1,738...

Introducción. El aislamiento impuesto durante la pandemia de COVID-19 podría influir en la adherencia a las terapias, especialmente en enfermos crónicos. El objetivo del estudio consistió en analizar el grado de cumplimiento de pacientes con síndrome de apnea obstructiva del sueño (SAOS) en tratamiento domiciliario con presión positiva continua (CP...

In this study, we use the overnight blood oxygen saturation (SpO2) signal along with convolutional neural networks (CNN) for the automatic estimation of pediatric sleep apnea-hypopnea syndrome (SAHS) severity. The few preceding studies have focused on the application of conventional feature extraction methods to obtain information from the SpO2 sig...

Spatial and frequency characterization of sleep spindles have been extensively addressed using M/EEG or fMRI recordings. However, its intraindividual variability across time has not been addressed. Here we propose to assess the intraindividual variability of sleep spindles in a time-resolved way by means of a trial-to-trial-variability (TTV) measur...

The reference standard to diagnose pediatric Obstructive Sleep Apnea (OSA) syndrome is an overnight polysomnographic evaluation. When polysomnography is either unavailable or has limited availability, OSA screening may comprise the automatic analysis of a minimum number of signals. The primary objective of this study was to evaluate the complementa...

The most appropriate physiological signals to develop simplified as well as accurate screening tests for obstructive sleep apnoea (OSA) remain unknown. This study aimed at assessing whether joint analysis of at-home oximetry and airflow recordings by means of machine-learning algorithms leads to a significant diagnostic performance increase compare...

Background and objective: In-laboratory overnight polysomnography (PSG) is the gold standard method to diagnose the sleep apnoea-hypopnoea syndrome (SAHS). PSG is a complex, expensive, labour-intensive and time-consuming test. Consequently, simplified diagnostic methods are desirable. We propose the analysis of the airflow (AF) signal by means of r...

Pediatric sleep apnea-hypopnea syndrome (SAHS) is a highly prevalent breathing disorder that is related to many negative consequences for the children's health and quality of life when it remains untreated. The gold standard for pediatric SAHS diagnosis (overnight polysomnography) has several limitations, which has led to the search for alternative...

The sleep apnea-hypopnea syndrome (SAHS) is a chronic respiratory disorder of high prevalence among children (up to 4%). Nocturnal polysomnography (PSG) is the gold standard method to diagnose SAHS, which is a complex, expensive, and time-consuming test. Consequently, alternative simplified methods are demanded. We propose the analysis of the respi...

RATIONALE. Obstructive sleep apnea (OSA) in children is a highly prevalent disease that hampers their cognitive development while also increasing the risk of behavioral disturbances. Sleep fragmentation and intermittent hypoxia have been implicated in these adverse outcomes. Even though EEG is used to evaluate sleep architecture during polysomnogra...

This study focuses on the at-home Sleep apnea-hypopnea syndrome (SAHS) severity estimation. Three percent oxygen desaturation index \( (ODI_{3} ) \) from nocturnal pulse-oximetry has been commonly evaluated as simplified alternative to polysomnography (PSG), the standard in-hospital diagnostic test. However, \( ODI_{3} \) has shown limited ability...

Chronic obstructive pulmonary disease (COPD) is one of the most prevalent lung diseases worldwide. COPD patients show major dysfunction in cardiac autonomic modulation due to sustained hypoxaemia, which has been significantly related to higher risk of cardiovascular disease. Obstructive sleep apnoea syndrome (OSAS) is a frequent comorbidity in COPD...

Background The gold standard for pediatric sleep apnea hypopnea syndrome (SAHS) is overnight polysomnography, which has several limitations. Thus, simplified diagnosis techniques become necessary. Objective The aim of this study is twofold: (i) to analyze the blood oxygen saturation (SpO2) signal from nocturnal oximetry by means of features from t...

Actual AHI from PSG and values of all the extracted features from the SpO2 signal (ODI3, statistical moments, PSD, and DWT features) of each subject in the optimization set. (XLSX)

The number of times each feature was selected with FCBF in the optimization set. (XLSX)

Actual AHI from PSG, values of all the extracted features from the SpO2 signal (ODI3, statistical moments, PSD, and DWT features), and the classification scores of LR, SVM, and MLP of each subject in the cross-validation set. (XLSX)

FULL-TEXT VIEW-ONLY VERSION of the paper: http://rdcu.be/HbJ1 Purpose: A variety of statistical models based on overnight oximetry has been proposed to simplify the detection of children with suspected obstructive sleep apnea syndrome (OSAS). Despite the usefulness reported, additional thorough comparative analyses are required. This study was ai...

Este estudio se centra en la caracterización del síndrome de la apnea-hipopnea del sueño (SAHS) infantil en el EEG nocturno. Para ello, se ha realizado un análisis espectral sobre los registros de 294 sujetos pediátricos (5-9 años) seleccionados en escuelas infantiles. El análisis espectral derivó en la definición de dos nuevas bandas de interés: i...

Background: Increasing accessibility to diagnostic resources would enable early detection of obstructive sleep apnea syndrome (OSAS) in children. Portable oximetry and automated signal processing techniques could speed up diagnosis. Aims and objectives: To assess symbolic dynamics as a reliable technique to characterize complex fluctuations of por...

Objective: To evaluate whether detrended fluctuation analysis (DFA) provides information that improves the diagnostic ability of the oximetry signal in the diagnosis of paediatric sleep apnoea-hypopnoea syndrome (SAHS). Approach: A database composed of 981 blood oxygen saturation (SpO2) recordings in children was used to extract DFA-derived feat...

Objective: This study is aimed at assessing symbolic dynamics as a reliable technique to characterise complex fluctuations of portable oximetry in the context of automated detection of childhood obstructive sleep apnoea-hypopnoea syndrome (OSAHS). Approach: Nocturnal oximetry signals from 142 children with suspected OSAHS were acquired using the...

Pediatric sleep apnea-hypopnea syndrome (SAHS) is a highly prevalent respiratory disorder that may impose many negative effects on the health and development of children. Due to the drawbacks of overnight polysomnography (PSG), the gold standard diagnosis technique, automated analysis of nocturnal oximetry has emerged as a simplified alternative. I...

This study aims at assessing the bispectral analysis of blood oxygen saturation (SpO2) from nocturnal oximetry to help in pediatric sleep apnea-hypopnea syndrome (SAHS) diagnosis. Recent studies have found excessive redundancy in the SAHS-related information usually extracted from SpO2, while proposing only two features as a reduced set to be used....

Overnight oximetry has been proposed as an accessible, simple, and reliable technique for obstructive sleep apnea syndrome (OSAS) diagnosis. From visual inspection to advanced signal processing, several studies demonstrated the usefulness of oximetry as screening tool. Technical advances increased the diagnostic ability of oximetry. Currently, high...

Background and objective: The aim of this study was to assess the utility of bispectrum-based oximetry approaches as a complementary tool to traditional techniques in the screening of pediatric sleep apnea-hypopnea syndrome (SAHS). Methods: 298 blood oxygen saturation (SpO2) signals from children ranging 0-13 years of age were recorded during ov...

The discrimination of early Alzheimer’s disease (AD) and its prodromal form (i.e., mild cognitive impairment, MCI) from cognitively healthy control (HC) subjects is crucial since the treatment is more effective in the first stages of the dementia. The aim of our study is to evaluate the usefulness of a methodology based on electroencephalography (E...

Background The coexistence of obstructive sleep apnea syndrome (OSAS) and chronic obstructive pulmonary disease (COPD) leads to increased morbidity and mortality. The development of home-based screening tests is essential to expedite diagnosis. Nevertheless, there is still very limited evidence on the effectiveness of portable monitoring to diagnos...

Actual AHI from PSG, ODI3, ODI4, and estimated AHI from the proposed oximetry-based MLP ANN both in the hospital and at home of each subject in the non-COPD test dataset. (XLSX)

Actual AHI from PSG, ODI3, ODI4, and estimated AHI from the proposed oximetry-based MLP ANN both in the hospital and at home of each subject in the COPD test dataset. (XLSX)

The aim of this paper is to evaluate the evolution of irregularity and variability of airflow (AF) signals as sleep apnoea-hypopnoea syndrome (SAHS) severity increases in children. We analyzed 501 AF recordings from children 6.2 ± 3.4 years old. The respiratory rate variability (RRV) signal, which is obtained from AF, was also estimated. The propos...

In the sleep apnea-hypopnea syndrome (SAHS) context, airflow signal plays a key role for the simplification of the diagnostic process. It is measured during the standard diagnostic test by the acquisition of two simultaneous sensors: a nasal prong pressure (NPP) and a thermistor (TH). The current study focuses on the comparison of their spectral co...

Sleep apnea hypopnea syndrome (SAHS) is a highly prevalent respiratory disorder that may cause many negative consequences for the health and development of children. The gold standard for diagnosis is the overnight polysomnography (PSG), which is a high cost, complex, intrusive, and time-demanding technique. To improve the early detection of pediat...

Untreated paediatric obstructive sleep apnoea syndrome (OSAS) can severely affect the development and quality of life of children. In-hospital polysomnography (PSG) is the gold standard for a definitive diagnosis though it is relatively unavailable and particularly intrusive. Nocturnal portable oximetry has emerged as a reliable technique for OSAS...

STUDY OBJECTIVES: Nocturnal oximetry has become known as a simple, readily available, and potentially useful diagnostic tool of childhood obstructive sleep apnea (OSA). However, at-home respiratory polygraphy (HRP) remains the preferred alternative to polysomnography (PSG) in unattended settings. The aim of this study was twofold: (1) to design and...

Resumen El Síndrome de la Apnea Hipopnea del Sueño (SAHS) es un trastorno respiratorio que puede originar consecuencias muy negativas para la salud de los niños. El test diagnóstico estándar es la polisomnografía (PSG), que es compleja, de elevado coste y disponibilidad limitada. El objetivo de este estudio es analizar la capacidad diagnóstica de l...

Resumen El Síndrome de la Apnea Hipopnea del Sueño (SAHS) es un trastorno respiratorio que puede originar consecuencias muy negativas para la salud de los niños. El test diagnóstico estándar es la polisomnografía (PSG), que es compleja, de elevado coste y disponibilidad limitada. El objetivo de este estudio es analizar la capacidad diagnóstica de l...

Este estudio evalúa la capacidad diagnóstica de la señal de flujo aéreo monocanal para ayudar a identificar el Síndrome de Apnea-Hipopnea del Sueño (SAHS) pediátrico. Se han analizado 501 registros procedentes de niños (6.21±3.41 años). Se ha propuesto una metodología en tres etapas: (i) análisis espectral, (ii) selección de características relevan...

Background. The development of home-based screening tests in sleep apnoea-hypopnoea syndrome (SAHS) diagnosis is essential to increase the accessibility to diagnostic facilities. Chronic obstructive pulmonary disease (COPD) is very prevalent among SAHS patients. However, almost all studies assessing home-based screening tests for SAHS excluded pati...

Background. Paediatric obstructive sleep apnoea-hypopnoea syndrome (OSAHS) has emerged as a frequent and concerning medical condition in the past 2-3 decades. In-laboratory overnight polysomnography (PSG) is the gold standard diagnostic technique but is complex and relatively inaccessible. Objectives. Blood oxygen saturation (SpO2) from nocturnal o...

Sleep apnea-hypopnea syndrome (SAHS) is a chronic sleep-related breathing disorder, which is currently considered a major health problem. In-lab nocturnal polysomnography (NPSG) is the gold standard diagnostic technique though it is complex and relatively unavailable. On the other hand, the analysis of blood oxygen saturation (SpO2) from nocturnal...

This paper aims at evaluating a novel multiclass methodology to establish Sleep Apnea-Hypopnea Syndrome (SAHS) severity by the use of single-channel athome oximetry recordings. The study involved 320 participants derived to a specialized sleep unit due to SAHS suspicion. These were assigned to one out of the four SAHS severity degrees according to...

The relationship between sleep apnoea–hypopnoea syndrome (SAHS) severity and the regularity of nocturnal oxygen saturation (SaO2) recordings was analysed. Three different methods were proposed to quantify regularity: approximate entropy (AEn), sample entropy (SEn) and kernel entropy (KEn). A total of 240 subjects suspected of suffering from SAHS to...

El síndrome de apnea-hipopnea del sueño (SAHS) es un trastorno respiratorio relacionado con el sueño de elevada prevalencia. Si no se diagnostica correctamente puede tener graves consecuencias en la calidad de vida y en la salud de los pacientes. En el presente estudio se ha diseñado y evaluado un nuevo protocolo de screening de pacientes basado en...