Sami Nikkonen

Sami Nikkonen
University of Eastern Finland | UEF · Department of Applied Physics

Ph.D.

About

30
Publications
3,232
Reads
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199
Citations
Additional affiliations
November 2020 - present
University of Eastern Finland
Position
  • PostDoc Position
November 2020 - present
Kuopio University Hospital
Position
  • PostDoc Position
September 2017 - November 2020
University of Eastern Finland
Position
  • Researcher
Education
November 2017 - November 2020
University of Eastern Finland
Field of study
  • Applied Physics
September 2012 - June 2017
University of Eastern Finland
Field of study
  • Applied Physics

Publications

Publications (30)
Article
Background and objective Many sleep recording software used in clinical settings have some tools to automatically analyze the blood oxygen saturation (SpO2) signal by detecting desaturations. However, these tools are often inadequate for scientific research as they do not provide SpO2 signal-based parameters which are superior in the estimation of...
Article
Full-text available
Background: Obstructive sleep apnea (OSA) is associated with vascular diseases from which stroke and sudden cardiac death are the most significant ones. It is known that disturbances of the autonomic nervous system and electrocardiographic changes are seen in patients with a previous cerebrovascular event. However, the pathophysiological cascade b...
Article
Full-text available
Novel diagnostic markers for obstructive sleep apnea beyond the apnea–hypopnea index (AHI) have been introduced. There are no studies on their association with markers of subclinical myocardial injury. We assessed the association between novel desaturation parameters and elevated cardiac troponin I and T. Participants with polysomnography (498) fro...
Article
We have previously developed an ambulatory electrode set (AES) for the measurement of electroencephalography (EEG), electrooculography (EOG), and electromyography (EMG). The AES has been proven to be suitable for manual sleep staging and self-application in in- home polysomnography (PSG). To further facilitate the diagnostics of various sleep disor...
Article
Sleep disorders form a massive global health burden and there is an increasing need for simple and cost-efficient sleep recording devices. Recent machine learning-based approaches have already achieved scoring accuracy of sleep recordings on par with manual scoring, even with reduced recording montages. Simple and inexpensive monitoring over multip...
Article
Full-text available
Intermittent hypoxaemia is a risk factor for numerous diseases. However, the reverse pathway remains unclear. Therefore, we investigated whether pre‐existing hypertension, diabetes or cardiovascular diseases are associated with the worsening of intermittent hypoxaemia. Among the included 2,535 Sleep Heart Health Study participants, hypertension (n...
Article
Full-text available
Study Objectives Obesity, older age, and male sex are recognized risk factors for sleep apnea. However, it is unclear whether the severity of hypoxic burden, an essential feature of sleep apnea, is associated with the risk of sleep apnea worsening. Thus, we investigated our hypothesis that the worsening of sleep apnea is expedited in individuals wi...
Article
Full-text available
The diagnosis of obstructive sleep apnea is based on daytime symptoms and the frequency of respiratory events during the night. The respiratory events are scored manually from polysomnographic recordings, which is time-consuming and expensive. Therefore, automatic scoring methods could considerably improve the efficiency of sleep apnea diagnostics...
Article
Full-text available
Low long-term heart rate variability (HRV), often observed in obstructive sleep apnea (OSA) patients, is a known risk factor for cardiovascular diseases. However, it is unclear how the type or duration of individual respiratory events modulate ultra-short-term HRV and beat-to-beat intervals (RR intervals). We aimed to examine the sex-specific chang...
Article
Full-text available
Current diagnostics of sleep apnea relies on the time-consuming manual analysis of complex sleep registrations, which is impractical for routine screening in hospitalized patients with a high probability for sleep apnea, e.g. those experiencing acute stroke or transient ischemic attacks (TIA). To overcome this shortcoming, we aimed to develop a con...
Article
Background As nocturnal hypoxemia and heart rate variability are associated with excessive daytime sleepiness (EDS) related to OSA, we hypothesize that the power spectral densities (PSD) of nocturnal pulse oximetry signals could be utilized in the assessment of EDS. Thus, we aimed to investigate if PSDs contain features that are related to EDS and...
Article
Full-text available
A common symptom of obstructive sleep apnea (OSA) is excessive daytime sleepiness (EDS). The gold standard test for EDS is the multiple sleep latency test (MSLT). However, due to its high cost, MSLT is not routinely conducted for OSA patients and EDS is instead evaluated using sleep questionnaires. This is problematic however, since sleep questionn...
Article
Full-text available
Study Objectives Accurate identification of sleep stages is essential in the diagnosis of sleep disorders (e.g. obstructive sleep apnea, OSA) but relies on labor-intensive EEG-based manual scoring. Furthermore, long-term assessment of sleep relies on actigraphy differentiating only between wake and sleep periods without identifying specific sleep s...
Article
Full-text available
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Article
Full-text available
Background Diagnostics of obstructive sleep apnea (OSA) is based on apnea-hypopnea index (AHI) determined as full-night average of occurred events. We investigate our hypothesis that intra-night variation in the frequency of obstructive events affects diagnostics and prognostics of OSA and should therefore be considered in clinical practice. Metho...
Article
Full-text available
The identification of sleep stages is essential in the diagnostics of sleep disorders, among which obstructive sleep apnea (OSA) is one of the most prevalent. However, manual scoring of sleep stages is time-consuming, subjective, and costly. To overcome this shortcoming, we aimed to develop an accurate deep learning approach for automatic classific...
Article
Full-text available
The severity of obstructive sleep apnea (OSA) is classified using apnea-hypopnea index (AHI). Accurate determination of AHI currently requires manual analysis and complicated registration setup making it expensive and labor intensive. Partially for these reasons, OSA is a heavily underdiagnosed disease as only 7% of women and 18% of men suffering f...
Poster
Full-text available
Severity of obstructive sleep apnea (OSA) is conventionally classified using apnea-hypopnea index which is determined by manually scoring sleep recordings. This makes the determination of OSA severity expensive and labor intensive. Therefore, the aim of this study was to train an artificial neural network for easy and automatic estimation of OSA se...
Poster
Full-text available
Apnea-hypopnea index (AHI) is determined as full night average and therefore hides the possible intra-night variations in OSA severity. In this study, we analyzed sleep recordings from 1989 patients with suspected OSA and calculated the number and severity of individual respiratory events first 6 hours of sleep. The frequency of respiratory events,...
Conference Paper
Obstructive sleep apnea (OSA) is a highly prevalent disease with severe health consequences. The severity of OSA is estimated with apnea-hypopnea-index (AHI). OSA is often treated with continuous positive airway pressure (CPAP). The aim of the current work was to create a numerical simulator showing benefits of different levels of usage of CPAP tre...
Article
The severity of obstructive sleep apnea is clinically assessed mainly using the apnea–hypopnea index. Based on the apnea–hypopnea index, patients are classified into four severity groups: non‐obstructive sleep apnea (apnea–hypopnea index < 5); mild (5 ≤ apnea–hypopnea index < 15); moderate (15 ≤ apnea–hypopnea index < 30); and severe obstructive sl...
Article
Objective: Adherence to continuous positive airway pressure (CPAP) is often limited. The aim of the current work was to create a simulation tool to enable determination of the individual CPAP therapy time required to normalize apnea-hypopnea index (AHI) (<5 events h-1) in a cohort of OSA patients. Approach: Polygraphic studies of 1989 consecutiv...
Conference Paper
Introduction Obstructive sleep apnea (OSA) is a common disease with severe health consequences most commonly treated with continuous positive airway pressure (CPAP) device. However, the adherence to CPAP treatment is often limited and the usage of the CPAP device can be only around 4 h per night after 1 month usage (Chai-Coetzer et al., 2013). Poss...
Conference Paper
Type 1 diabetes is a metabolic disorder, which has been associated with decreased heart rate variability (HRV) and increased risk for adverse cardiac events. The aim of this paper was to examine HRV dynamics during a cardiorespiratory exercise test. 13 male subjects with type 1 diabetes (age 33.0±6.7 years) and 25 healthy male controls (age 33.7±7....

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