C-Trend parameters and possibilities of federated learning

Abstract. In this observational study, federated learning, a cutting-edge approach to machine learning, was applied to one of the parameters provided by C-Trend Technology developed by Cerenion Oy. The aim was to compare the performance of federated learning to that of conventional machine learning. Additionally, the potential of federated learning for resolving the privacy concerns that prevent machine learning from realizing its full potential in the medical field was explored. Federated learning was applied to burst-suppression ratio’s machine learning and it was compared to the conventional machine learning of burst-suppression ratio calculated on the same dataset. A suitable aggregation method was developed and used in the updating of the global model. The performance metrics were compared and a descriptive analysis including box plots and histograms was conducted. As anticipated, towards the end of the training, federated learning’s performance was able to approach that of conventional machine learning. The strategy can be regarded to be valid because the performance metric values remained below the set test criterion levels. With this strategy, we will potentially be able to make use of data that would normally be kept confidential and, as we gain access to more data, eventually develop machine learning models that perform better. Federated learning has some great advantages and utilizing it in the context of qEEGs’ machine learning could potentially lead to models, which reach better performance by receiving data from multiple institutions without the difficulties of privacy restrictions. Some possible future directions include an implementation on heterogeneous data and on larger data volume.C-Trend-teknologian parametrit ja federoidun oppimisen mahdollisuudet. Tiivistelmä. Tässä havainnointitutkimuksessa federoitua oppimista, koneoppimisen huippuluokan lähestymistapaa, sovellettiin yhteen Cerenion Oy:n kehittämään C-Trend-teknologian tarjoamaan parametriin. Tavoitteena oli verrata federoidun oppimisen suorituskykyä perinteisen koneoppimisen suorituskykyyn. Lisäksi tutkittiin federoidun oppimisen mahdollisuuksia ratkaista yksityisyyden suojaan liittyviä rajoitteita, jotka estävät koneoppimista hyödyntämästä täyttä potentiaaliaan lääketieteen alalla. Federoitua oppimista sovellettiin purskevaimentumasuhteen koneoppimiseen ja sitä verrattiin purskevaimentumasuhteen laskemiseen, johon käytettiin perinteistä koneoppimista. Kummankin laskentaan käytettiin samaa dataa. Sopiva aggregointimenetelmä kehitettiin, jota käytettiin globaalin mallin päivittämisessä. Suorituskykymittareiden tuloksia verrattiin keskenään ja tehtiin kuvaileva analyysi, johon sisältyi laatikkokuvioita ja histogrammeja. Odotetusti opetuksen loppupuolella federoidun oppimisen suorituskyky pystyi lähestymään perinteisen koneoppimisen suorituskykyä. Menetelmää voidaan pitää pätevänä, koska suorituskykymittarin arvot pysyivät alle asetettujen testikriteerien tasojen. Tämän menetelmän avulla voimme ehkä hyödyntää dataa, joka normaalisti pidettäisiin salassa, ja kun saamme lisää dataa käyttöömme, voimme lopulta kehittää koneoppimismalleja, jotka saavuttavat paremman suorituskyvyn. Federoidulla oppimisella on joitakin suuria etuja, ja sen hyödyntäminen qEEG:n koneoppimisen yhteydessä voisi mahdollisesti johtaa malleihin, jotka saavuttavat paremman suorituskyvyn saamalla tietoja useista eri lähteistä ilman yksityisyyden suojaan liittyviä rajoituksia. Joitakin mahdollisia tulevia suuntauksia ovat muun muassa heterogeenisen datan ja suurempien tietomäärien käyttö

Advances in Clinical Neurophysiology

Including some of the newest advances in the field of neurophysiology, this book can be considered as one of the treasures that interested scientists would like to collect. It discusses many disciplines of clinical neurophysiology that are, currently, crucial in the practice as they explain methods and findings of techniques that help to improve diagnosis and to ensure better treatment. While trying to rely on evidence-based facts, this book presents some new ideas to be applied and tested in the clinical practice. Advances in Clinical Neurophysiology is important not only for the neurophysiologists but also for clinicians interested or working in wide range of specialties such as neurology, neurosurgery, intensive care units, pediatrics and so on. Generally, this book is written and designed to all those involved in, interpreting or requesting neurophysiologic tests

Aerospace Medicine and Biology - A continuing bibliography with indexes

Annotated bibliography and indexes on Aerospace Medicine and Biology - Dec. 196

Autonomic nervous system biomarkers from multi-modal and model-based signal processing in mental health and illness

Esta tesis se centra en técnicas de procesado multimodal y basado en modelos de señales para derivar parámetros fisiológicos, es decir, biomarcadores, relacionados con el sistema nervioso autónomo (ANS). El desarrollo de nuevos métodos para derivar biomarcadores de ANS no invasivos en la salud y la enfermedad mental ofrece la posibilidad de mejorar la evaluación del estrés y la monitorización de la depresión. Para este fin, el presente documento se estructura en tres partes principales. En la Parte I, se proporciona unaintroducción a la salud y la enfermedad mental (Cap. 1). Además, se presenta un marco teórico para investigar la etiología de los trastornos mentales y el papel del estrés en la enfermedad mental (Cap. 2). También se destaca la importancia de los biomarcadores no invasivos para la evaluación del ANS, prestando especial atención en la depresión clínica (Cap. 3, 4). En la Parte II, se proporciona el marco metodológico para derivar biomarcadores del ANS. Las técnicas de procesado de señales incluyen el análisis conjunto de la variabilidad del rítmo cardíaco (HRV) y la señal respiratoria (Cap. 6), técnicas novedosas para derivar la señal respiratoria del electrocardiograma (ECG) (Cap. 7) y un análisis robusto que se basa en modelar la forma de ondas del pulso del fotopletismograma (PPG) (Ch. 8). En la Parte III, los biomarcadores del ANS se evalúan en la quantificacióndel estrés (Cap. 9) y en la monitorización de la depresión (Ch. 10).Parte I: La salud mental no solo está relacionada con ese estado positivo de bienestar, en el que un individuo puede enfrentar a las situaciones estresantes de la vida, sino también con la ausencia de enfermedad mental. La enfermedad o trastorno mental se puede definir como un trastorno emocional, cognitivo o conductual que causa un deterioro funcional sustancial en una o más actividades importantes de la vida. Los trastornos mentales más comunes, que muchas veces coexisten, son la ansiedad y el trastorno depresivo mayor (MDD). La enfermedad mental tiene un impacto negativo en la calidad de vida, ya que se asocia con pérdidas considerables en la salud y el funcionamiento, y aumenta ignificativamente el riesgo de una persona de padecer enfermedades ardiovasculares.Un instigador común que subyace a la comorbilidad entre el MDD, la patologíacardiovascular y la ansiedad es el estrés mental. El estrés es común en nuestra vida de rítmo rapido e influye en nuestra salud mental. A corto plazo, ANS controla la respuesta cardiovascular a estímulos estresantes. La regulación de parámetros fisiológicos, como el rítmo cardíaco, la frecuencia respiratoria y la presión arterial, permite que el organismo responda a cambios repentinos en el entorno. Sin embargo, la adaptación fisiológica a un fenómeno ambiental que ocurre regularmente altera los sistemas biológicos involucrados en la respuesta al estrés. Las alteraciones neurobiológicas en el cerebro pueden alterar lafunción del ANS. La disfunción del ANS y los cambios cerebrales estructurales tienen un impacto negativo en los procesos cognitivos, emocionales y conductuales, lo que conduce al desarrollo de una enfermedad mental.Parte II: El desarrollo de métodos novedosos para derivar biomarcadores del ANS no invasivos ofrece la posibilidad de mejorar la evaluacón del estrés en individuos sanos y la disfunción del ANS en pacientes con MDD. El análisis conjunto de varias bioseñales (enfoquemultimodal) permite la cuantificación de interacciones entre sistemas biológicos asociados con ANS, mientras que el modelado de bioseãles y el análisis posterior de los parámetros del modelo (enfoque basado en modelos) permite la cuantificación robusta de cambios en mecanismos fisiológicos relacionados con el ANS. Un método novedoso, quetiene en cuenta los fenómenos de acoplo de fase y frecuencia entre la respiración y las señales de HRV para evaluar el acoplo cardiorrespiratorio no lineal cuadrático se propone en el Cap. 6.3. En el Cap. 7 se proponen nuevas técnicas paramejorar lamonitorización de la respiración. En el Cap. 8, para aumentar la robustez de algunas medidas morfológicas que reflejan cambios en el tonno arterial, se considera el modelado del pulso PPG como una onda principal superpuesta con varias ondas reflejadas.Parte III: Los biomarcadores del ANS se evalúan en la cuantificación de diferentes tipos de estrés, ya sea fisiológico o psicológico, en individuos sanos, y luego, en la monitorización de la depresión. En presencia de estrés mental (Cap. 9.1), inducido por tareas cognitivas, los sujetos sanos muestran un incremento en la frecuencia respiratoria y un mayor número de interacciones no lineales entre la respiración y la seãl de HRV. Esto podría estar asociado con una activación simpática, pero también con una respiración menos regular. En presencia de estrés hemodinámico (Cap. 9.2), inducido por un cambio postural, los sujetos sanos muestran una reducción en el acoplo cardiorrespiratoriono lineal cuadrático, que podría estar relacionado con una retracción vagal. En presencia de estrés térmico (Cap. 9.3), inducido por la exposición a emperaturas ambientales elevadas, los sujetos sanos muestran un aumento del equilibrio simpatovagal. Esto demuestra que los biomarcadores ANS son capaces de evaluar diferentes tipos de estrés y pueden explorarse más en el contexto de la monitorización de la depresión. En el Cap. 10, se evalúan las diferencias en la función del ANS entre elMDD y los sujetos sanos durante un protocolo de estrés mental, no solo con los valores brutos de los biomarcadores del ANS, sino también con los índices de reactividad autónoma, que reflejan la capacidad deun individuo para afrontar con una situación desafiante. Los resultados muestran que la depresión se asocia con un desequilibrio autonómico, que se caracteriza por una mayor actividad simpática y una reducción de la distensibilidad arterial. Los índices de reactividad autónoma cuantificados por cambios, entre etapas de estrés y de recuperación, en los sustitutos de la rigidez arterial, como la pérdida de amplitud de PPG en las ondas reflejadas, muestran el mejor rendimiento en términos de correlación con el grado de la depresión, con un coeficiente de correlación r = −0.5. La correlación negativa implicaque un mayor grado de depresión se asocia con una disminución de la reactividadautónoma. El poder discriminativo de los biomarcadores del ANS se aprecia también por su alto rendimiento diagnóstico para clasificar a los sujetos como MDD o sanos, con una precisión de 80.0%. Por lo tanto, se puede concluir que los biomarcadores del ANS pueden usarse para evaluar el estrés y que la distensibilidad arterial deteriorada podría constituir un biomarcador de salud mental útil en el seguimiento de la depresión.This dissertation is focused on multi-modal and model-based signal processing techniques for deriving physiological parameters, i.e. biomarkers, related to the autonomic nervous system (ANS). The development of novel approaches for deriving noninvasive ANS biomarkers in mental health and illness offers the possibility to improve the assessment of stress and the monitoring of depression. For this purpose, the present document is structured in three main parts. In Part I, an introduction to mental health and illness is provided (Ch. 1). Moreover, a theoretical framework for investigating the etiology of mental disorders and the role of stress in mental illness is presented (Ch. 2). The importance of noninvasive biomarkers for ANS assessment, paying particular attention in clinical depression, is also highlighted (Ch. 3, 4). In Part II, themethodological framework for deriving ANS biomarkers is provided. Signal processing techniques include the joint analysis of heart rate variability (HRV) and respiratory signals (Ch. 6), novel techniques for deriving the respiratory signal from electrocardiogram (ECG) (Ch. 7), and a robust photoplethysmogram(PPG)waveform analysis based on amodel-based approach (Ch. 8). In Part III, ANS biomarkers are evaluated in stress assessment (Ch. 9) and in the monitoring of depression (Ch. 10). Part I:Mental health is not only related to that positive state ofwell-being, inwhich an individual can cope with the normal stresses of life, but also to the absence of mental illness. Mental illness or disorder can be defined as an emotional, cognitive, or behavioural disturbance that causes substantial functional impairment in one or more major life activities. The most common mental disorders, which are often co-occurring, are anxiety and major depressive disorder (MDD). Mental illness has a negative impact on the quality of life, since it is associated with considerable losses in health and functioning, and increases significantly a person’s risk for cardiovascular diseases. A common instigator underlying the co-morbidity between MDD, cardiovascular pathology, and anxiety is mental stress. Stress is common in our fast-paced society and strongly influences our mental health. In the short term, ANS controls the cardiovascular response to stressful stimuli. Regulation of physiological parameters, such as heart rate, respiratory rate, and blood pressure, allows the organism to respond to sudden changes in the environment. However, physiological adaptation to a regularly occurring environmental phenomenon alters biological systems involved in stress response. Neurobiological alterations in the brain can disrupt the function of the ANS. ANS dysfunction and structural brain changes have a negative impact on cognitive, emotional, and behavioral processes, thereby leading to development of mental illness. Part II: The development of novel approaches for deriving noninvasive ANS biomarkers offers the possibility to improve the assessment of stress in healthy individuals and ANS dysfunction in MDD patients. Joint analysis of various biosignals (multi-modal approach) allows for the quantification of interactions among biological systems associated with ANS, while the modeling of biosignals and subsequent analysis of the model’s parameters (model-based approach) allows for the robust quantification of changes in physiological mechanisms related to the ANS. A novel method, which takes into account both phase and frequency locking phenomena between respiration and HRV signals, for assessing quadratic nonlinear cardiorespiratory coupling is proposed in Ch. 6.3. Novel techniques for improving the monitoring of respiration are proposed in Ch. 7. In Ch. 8, to increase the robustness for some morphological measurements reflecting arterial tone changes, the modeling of the PPG pulse as amain wave superposed with several reflected waves is considered. Part III: ANS biomarkers are evaluated in the assessment of different types of stress, either physiological or psychological, in healthy individuals, and then, in the monitoring of depression. In the presence of mental stress (Ch. 9.1), induced by cognitive tasks, healthy subjects show an increment in the respiratory rate and higher number of nonlinear interactions between respiration and HRV signal, which might be associated with a sympathetic activation, but also with a less regular breathing. In the presence of hemodynamic stress (Ch. 9.2), induced by a postural change, healthy subjects show a reduction in strength of the quadratic nonlinear cardiorespiratory coupling, whichmight be related to a vagal withdrawal. In the presence of heat stress (Ch. 9.3), induced by exposure to elevated environmental temperatures, healthy subjects show an increased sympathovagal balance. This demonstrates that ANS biomarkers are able to assess different types of stress and they can be further explored in the context of depression monitoring. In Ch. 10, differences in ANS function between MDD and healthy subjects during a mental stress protocol are assessed, not only with the raw values of ANS biomarkers but also with autonomic reactivity indices, which reflect the ability of an individual to copewith a challenging situation. Results show that depression is associated with autonomic imbalance, characterized by increased sympathetic activity and reduced arterial compliance. Autonomic reactivity indices quantified by changes, from stress to recovery, in arterial stiffness surrogates, such as the PPG amplitude loss in wave reflections, show the best performance in terms of correlation with depression severity, yielding to correlation coefficient r = −0.5. The negative correlation implies that a higher degree of depression is associated with a decreased autonomic reactivity. The discriminative power of ANS biomarkers is supported by their high diagnostic performance for classifying subjects as having MDD or not, yielding to accuracy of 80.0%. Therefore, it can be concluded that ANS biomarkers can be used for assessing stress and that impaired arterial compliance might constitute a biomarker of mental health useful in the monitoring of depression.<br /

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 297)

This bibliography lists 89 reports, articles and other documents introduced into the NASA scientific and technical information system in April, 1987

Sleep and Breathing in Preterm Infants : Polysomnography Studies on the Effects of Caffeine and Supplemental Oxygen

Sleep-disordered breathing in preterm infants is common and is a prominent issue in neonatal care. Preterm infants express breathing pauses called apneas, and periodic breathing (PB) consisting of repetitive intervals of short apneas and periods of hyperpnea. Apneas are commonly divided into central, obstructive, and mixed depending on the presence of absence of breathing effort. Central apneas show no airflow nor any breathing attempts. Obstructive apneas show breathing attempts in which airflow is restricted due to collapsed upper airways. Mixed apneas are a combination of these two, usually commencing as a central apnea, followed by obstructive breaths. In clinical neonatal practice, apneas are commonly not divided into central, obstructive, or mixed. Apneas in these infants are considered pathologic if they cause significant hypoxia, or bradycardia, or last for over 15 to 20 seconds. These respiratory pauses are called apnea of prematurity (AOP) irrespective of the presence or absence of upper airway obstruction. The use of the concept of AOP is not necessarily relevant as varying apnea types respond to different treatment methods. The significance of PB in preterm infants is disputed. PB causes intermittent hypoxia, which can, for example, lead to increased appearance of apneas and can impair preterm infants’ development. The approach of treatment depends on the degree of sleep-disordered breathing and on the treating center. Treatment modalities vary: invasive ventilatory support, high-flow nasal cannulas, continuous positive airway pressure, oxygen therapy, and methylxanthines such as caffeine or theophylline. In preterm infants, caffeine reduces the number of apneas and PB, and reduces the need for mechanical ventilation. It also promotes development. Supplemental oxygen stabilizes breathing and enhances oxygenation. Whereas the effect of supplemental oxygen is mediated through the peripheral chemoreceptors, the effect of caffeine as a breathing stimulant is most likely mediated through the stimulation of the central respiratory centers. Despite caffeine’s routine use in clinical practice, its effects on sleep and respiratory control in preterm infants are yet to be well established. Caffeine has a general stimulative effect on the central nervous system, and in adults and older children it increases alertness and prevents falling asleep; in preterm infants such an effect is not evident. Sleep in preterm infants differs significantly from sleep in older infants, children, and adults. Preterm infants spend most of their time asleep without any circadian rhythm. In contrast to later in life, their sleep is occupied by 40 to 60% of rapid-eye movement (REM) sleep compared, later in life, to around 15%. REM sleep is susceptible to disturbance, and in premature infants, respiratory disorders and intensive care with medical equipment and procedures interfere with sleep, especially with REM sleep. The development of sleep, sleep stages, and especially REM sleep are fundamental for normal development. Thus, knowledge about the effect of treatments on sleep in preterm infants is vital. This thesis study is based on polysomnographic data in late-preterm infants. We studied 21 preterm infants cared for in the neonatal wards of Helsinki University Hospital between 2013 and 2018. These infants were estimated by the pediatrician in charge of their care to need commencing of caffeine treatment for apneas or the presence of long periods of PB. We performed full polysomnography (PSG) studies in three phases: 1) at baseline prior to any intervention, 2) on supplemental oxygen, and 3) on the day after initiation of caffeine citrate treatment The analysis of the PSG studies comprised explicit sleep analysis, analysis of breathing disorders such as apneas and PB, arousals, and heart rate, and the effects of supplemental oxygen and of caffeine on these events. The results of this thesis study showed that sleep of preterm infants was fragmented by frequent arousal-type phenomena. Apneas seemed to have no disturbing effect on sleep and apneas rarely ended in an arousal from sleep. Therefore, apnea termination seems to be independent from arousal in preterm infants. Supplemental oxygen appeared to mildly increase arousal in response to AOP-defined apneas. Hypoxia did not effectively cause arousals in preterm infants. However, caffeine increased the rate of arousal in response to hypoxia. Caffeine and supplemental oxygen did not affect sleep, and despite acting as a respiratory stimulant, caffeine caused no notable central nervous system stimulation. The infants presented with long, AOP-defined apneas mainly in REM sleep, independent of their PB. These AOP-defined apneas were mostly of a mixed type with a considerably long central apnea before obstructive breathing efforts commenced, and they were to some degree affected by caffeine treatment. PB emerged as a state of mild hyperventilation, it appeared dominantly in non-REM sleep, and it caused intermittent hypoxia. Conventional oxygen saturation measurement with long averaging intervals may often miss this intermittent hypoxia. PB and subsequent intermittent hypoxia showed effective dampening with caffeine, and even greater dampening with supplemental oxygen. In conclusion, in preterm infants, sleep-disordered breathing consisted of PB in NREM sleep and long apneas either during falling asleep or in REM sleep. Long apneas were most often mixed apneas commencing as central apneas but continuing as upper airway obstruction. PB shared characteristics similar to those evident later in life. It appeared as a state of mild hyperventilation and responded both to supplemental oxygen and to caffeine. Caffeine did not appear to be a general central nervous system stimulant in preterm infants, which should further reassure us as to its use in such infants.Ennenaikaisesti syntyneillä lapsilla eli keskosilla unenaikaiset hengityshäiriöt ovat yleisiä ja ne ovat yksi keskosten hoidon keskeisistä ongelmista. Näitä hengityshäiriöitä ovat mm. hengityskatkokset eli apneat sekä jaksottainen eli periodien hengitys, joka koostuu toistuvista lyhyiden sentraalisen apneoiden ja niiden välissä olevien ylihengitysjaksojen sykleistä. Apneat jaetaan yleisesti sentraalisiin, tukoksellisiin (obstruktiivisiin) ja sekamuotoisiin sen perusteella, liittykö niihin hengitysyrityksiä vai ei. Kliinisessä käytännössä keskosilla ja vastasyntyneillä apneatyyppien jakoa ei tavanomaisesti tehdä. Heillä apneat arvioidaan merkittäviksi, jos niihin liittyy hapetustason tai syketason merkittävää laskua tai niiden kesto on yli 15–20 sekuntia. Kuitenkin eri apneatyyppien hoitoon tehoavat parhaiten eri hoitomenetelmät. Keskosilla esiintyvän jaksottaisen hengityksen merkitys on kiistelty ja sen normaalivaihtelua ei varmuudella tunneta. Jaksottaiseen hengitykseen on todettu liittyvän lyhyitä intermittoivia hapenpuutejaksoja. Tällaisen intermittoivan hapenpuutteen on todettu liittyvän keskosilla mm. apneoiden lisääntymiseen sekä heikompaan kehitykseen. Kuitenkin sen merkityksestä keskosten kehitykseen on eriäviä arvioita. Keskosten hengityshäiriöiden yleisiä hoitomuotoja ovat vaikeusasteen mukaan hengityskonehoito, ylipainehengityshoito, korkeavirtausviiksihoito, happihoito ja kofeiinilääkitys. Keskosilla kofeiini vähentää apneoiden määrää, tasoittaa hengitystä, vähentää hengityskonehoidon tarvetta sekä parantaa keskosten kehitystä. Myös lisähappi tasoittaa keskosten hengitystä. Lisähappi vaikuttaa hengitykseen perifeeristen hapen ja hiilidioksidin aistinelimen, karotiskerästen, toiminnan lamaamisen kautta. Kofeiini puolestaan tehostaa hengitystä ja sen vaikutus välittyy ilmeisesti pääosin keskushermoston hengityskeskusten kautta. Aikuisilla ja vanhemmilla lapsilla kofeiini aktivoi keskushermostoa ja lisää valvetta. Kofeiinin rutiininomaisesta käytöstä huolimatta tietomme sen vaikutuksista keskosten nukkumiseen ja unen laatuun on vähäistä. Keskoset nukkuvat suurimman osan ajastaan, ja heidän unestaan valtaosa on vilke- eli REM-unta. REM-uni on herkkä häiriintymään ja keskoskaudella hengityshäiriöt sekä tehohoito häiritsevät unta, etenkin REM-unta. Unen ja sen eri vaiheiden, etenkin REM-unen, häiriintyminen haittaa normaalia kehitystä. Siten tieto keskosilla käytettävien hoitojen vaikutuksesta uneen on tärkeää. Tämä väitöskirjatyö pohjautuu keskosilla tehtyihin laajoihin unitutkimuksiin (polysomnografia, PSG). Tutkimme HUS Helsingin Yliopistollisen sairaalan Jorvin ja Kätilöopiston sairaaloiden vastasyntyneiden osastoilla 21 keskosta vuosina 2013–2018. Näillä lapsilla oli todettu merkittäviä apneoita tai taipumus runsaaseen periodiseen hengitykseen, minkä vuoksi heille suunniteltiin kliinisin perustein kofeiinihoidon aloitusta. Teimme näille lapsille laajat unitutkimukset kolmessa vaiheessa: 1) lähtötilanteessa ennen interventiota, 2) lisähapen annon aikana ja 3) kofeiinihoidon aloittamista seuraavana päivänä. Rekisteröintien pohjalta arvioimme tutkittavien unta ja sen eri vaiheita, hengityshäiriöitä (apneoita ja jaksottaista hengitystä) ja niiden esiintymistä eri univaiheissa sekä lisähapen ja kofeiinin vaikutusta. Tämän väitöskirjatyön tulokset osoittavat, että keskoslasten uni oli toistuvien spontaanien havahtumisten vuoksi huomattavan paljon pirstaleisempaa kuin silminnähden arvioituna. Apneoilla ei näyttänyt olevan unta häiritsevää vaikutusta, ja apneat ja hapenpuutejaksot päättyivät harvoin havahtumiseen. Apneoiden päättyminen vaikuttaa olevan keskosilla havahtumisesta riippumatonta, mikä johtunee ensisijaisesti keskosille ominaisista alhaisista vasteista hapenpuutteeseen. Lisähappi vaikutti hieman lisäävän havahtumisia pidempiin apneoihin. Hapenpuute ei ollut tehokas herättäjä, mutta kofeiini lisäsi siihen havahtumista. Kofeiini ja lisähappi eivät vaikuttaneet uneen. Johtopäätöksenä toteamme, että vaikka kofeiini toimi hengitystä stimuloivana lääkkeenä, se ei aiheuttanut merkittävää keskushermoston stimulaatiota näillä keskosilla, mikä edelleen vahvistaa kofeiinin turvallisuutta keskosten hengityshäiriöiden hoidossa. Tutkituilla keskosilla esiintyi yksittäisiä pitkiä keskosten apneoiksi määriteltyjä apneoita (apnea of prematurity, AOP) pääosin REM-unen aikana, erillään jaksottaisesta hengityksestä. Nämä apneat olivat pääosin sekamuotoisia, mutta usein niiden obstruktiivista osiota edelsi pitkä sentraalisen apnean osio. Kofeiini vähensi hieman näitä sekamuotoisia apneoita. Periodinen hengitys näyttäytyi hyperventilaatiotilana ja esiintyi pääosin rauhallisessa (NREM) unessa, ollen samankaltaista kuin myöhemmällä iällä. Siihen liittyi säännönmukaisesti toistuvat hapenpuutejaksot. Nämä jaksot jäävät huomaamatta, jos veren happikyllästeisyyden mittalaitteessa (pulssioksimetri) käytetään kliinisessä käytössä tavanomaista, pitkää keskiarvoistusaikaa. Kofeiini ja erityisesti lisähappi vähensivät huomattavasti periodista hengitystä ja niihin liittyneitä hapenpuutejaksoja

Medical microprocessor systems

The practical classes and laboratory work in the discipline "Medical microprocessor systems", performed using software in the programming environment of microprocessors Texas Instruments (Code Composer Studio) and using of digital microprocessors of the Texas Instruments DSK6400 family, and models of electrical equipment in the environment of graphical programming LabVIEW 2010.Лабораторний практикум з програмування та побудови медичних мікропроцесорних систем, який викладено у навчальному посібнику допомагає накопичувати й ефективно використовувати отриману інформацію з теоретичного курсу на всіх стадіях навчального процесу, що є важливим для підготовки магістрів та необхідною ланкою у науковому пізнанні практичних основ біомедичної електроніки.The laboratory workshop on the programming and construction of medical microprocessor systems, which is outlined in the tutorial, helps to accumulate and effectively use the information obtained from a theoretical course at all stages of the educational process, which is important for the preparation of masters and a necessary link in the scientific knowledge of the practical basics of biomedicine.Лабораторный практикум по программированию и построению медицинских микропроцессорных систем, который изложен в учебном пособии помогает накапливать и эффективно использовать полученную информацию из теоретического курса на всех стадиях учебного процесса, что важно для подготовки магистров и является необходимым звеном в научном познании практических основ биомедицинской электроники