Detection and Assessment of Sleep-Disordered Breathing with Special Interest of Prolonged Partial Obstruction

Sleep-disordered breathing (SDB) has become more common and puts more strain on public health services than ever before. Obstructive sleep apnea (OSA) and its health consequences such as different cardiovascular diseases are nowadays well recognized. In addition to OSA, attention has recently been paid to another SDB; prolonged partial obstruction. However, it is often undiagnosed and easily left untreated because of the low number of respiratory events during polysomnography recording. This patient group has found to present with more atypical subjective symptoms than OSA patients.Polysomnography (PSG) is considered to be the gold standard in reference methods in SDB diagnostics. PSG is a demanding and laborious multichannel recording method and often requires subjects to spend one night in a sleep laboratory. There is long tradition in Finland to use mattress sensors in SDB diagnostics. Recently, smaller electromechanical film transducer (Emfit) mattresses have replaced the old Static Charge-Sensitive Bed (SCSB) mattresses. However, a proper clinical validation of Emfit mattresses in SDB diagnostics has not been carried out.In this work, the use of Emfit recording in the detection of sleep apneas, hypopneas, and prolonged partial obstruction with increased respiratory effort was evaluated. The general aim of the thesis is to develop and improve the diagnostic methods for sleep-related breathing disorders.Comparisons with both PSG with nasal pressure recording and transesophageal pressure were made. Special attention was paid to the existence of the spiking phenomenon in the Emfit mattress in relation to changes in negative intrathoracic pressure in estimating increased respiratory effort. This entails monitoring the esophageal pressure as a part of nocturnal polysomnography. The recording method is demanding and uncomfortable and is usually not used with ordinary sleep laboratory patients. Thus, reliable and easy indirect quantification methods for respiratory effort are needed in clinical work. According to the results presented in this work, the Emfit signal reveals increased respiratory effort as well as apneas/hypopneas.To find out the prevalence and consequences of prolonged partial obstruction among sleep laboratory patients was another aim of this thesis. This was done by retrospective analyses of sleep laboratory patients from one year. The prevalence of patients with prolonged partial obstruction was 11%. They were as sleepy as OSA patients, but their life quality was worse, as assessed by a survey. These results, along with the findings of the heart rate variation evaluation carried out in this thesis, suggest that prolonged partial obstruction and OSA should be considered as different entities of SDB.With the Emfit mattress sensor, the SDB types can be differentiated, which is expected to enhance the accuracy of diagnostics. However, there is increasing need for easy and cheap screening methods to evaluate nocturnal breathing. In this respect, the usability of compressed tracheal sound signal scoring in SDB screening was estimated. The method reveals apneas and hypopneas but, according to the present findings, it can also be used in the detection of prolonged partial obstruction. The findings encourage the use of compressed tracheal sound analysis in screening different SDB.The analysis of sleep recordings is still based on a doctor’s subjective and visual estimation. To date, no generally accepted and sufficiently reliable automatic analysis method exists. Robust, automatic quantification methods with easier techniques for non-invasive sleep recording would enable the analysis methods to be also used for screening purposes. In this technology-orientated world, people could take much more responsibility and take care of themselves better by following their own biosignals and by changing their health habits earlier. The need for good sleep as a necessity for good life and health is widely recognized

Unenaikaisen hengitysäänen ja ruokatorvipaineen yhteydestä

Tavoitteet: Uniapnean ja pitkäkestoisen ylähengitystieahtauman diagnosoimiseen tarvitaan helppoja, halpoja ja luotettavia testejä. Tutkimme kaulalla olevan mikrofonin luotettavuutta diagnostiikassa vertaamalla sitä kultaiseen standardiin eli ruokatorvipaineeseen. Pilottiluonteisen selvityksemme perusteella oletuksena oli, että HeLSA-signaalin plain-vaiheen aikana ruokatorvipaine olisi normaali eli yli -8 cmH2O. Toisena oletuksena oli, että thick-vaiheen aikana ruokatorvipaine olisi alle -8 cmH2O. Kolmantena oletuksena oli, että thin-vaiheen aikana ruokatorvipaine olisi myös alle -8 cmH2O. Menetelmät: Aineisto koostui 20 unilaboratoriossa nukkuneesta henkilöstä. Potilaille tehtiin laaja unipolygrafia ja heiltä mitattiin myös ruokatorvipaine ja yönaikaista hengitysääntä mikrofonilla. Hengitysääni muutettiin kompressoiduksi HeLSA-dataksi, josta thin, thick ja plain vaiheet luokiteltiin. Saadusta datasta tutkittiin ruokatorvipaineen pienin arvo kunkin epokin aikana, sekä prosenttiosuus ajasta jolloin ruokatorvipaine oli alle -8 cmH2O. Tulokset: Thin, thick ja plain -epokkien pienimmät ruokatorvipainearvot eivät eronneet tilastollisesti toisistaan (p=0,097). Prosenttiosuus ajasta jolloin ruokatorvipaine oli alle -8 cmH2O thin-, thick- ja plain-epokeissa vaihteli epokkien välillä tilastollisesti merkittävästi (p=0,05). Tarkemmassa analyysissä ei ollut tilastollista merkitsevyyttä thin vs. thick, thin vs. plain vai thick vs. plain. Päätelmät: Ruokatorvipaine, ja siis rintakehän sisäinen paine on erilainen erityyppisen hengitysäänen aikana. Hengitysäänen muodon analysoiminen visuaalisesti on helppoa. Tämä työ viittaa siihen suuntaan, että kompressoidun hengitysäänen muoto voisi toimia helppona merkkinä hengityksen öisestä ahtautumisesta

Tracheal Breath Sounds - instrumentation and origin

Tässä työssä tehtiin kirjallisuuskatsaus trakeasta kuultavien hengitysäänien instrumentointiin, normaaleihin ja epätavallisiin trakeasta kuultaviin ääniin. Katsauksessa havaittiin, että hengitysäänten rekisteröintiin käytettävien sensoreiden suunnittelulla voidaan vaikuttaa rekisteröityihin ääniin. Erityisesti ilmakytkettyjen kontaktimikrofonien ilmakammiolla voi olla suuri vaikutus mitattuihin ääniin. Normaalien trakeahengitysäänien alkuperä on aeroakustinen. Ilmavirtauksen nopeuden kasvaessa laminaarinen virtaus irtautuu henkitorven seinämästä ja virtaukseen syntyy pyörteitä. Virtaus on muuttunut turbulenttiseksi. Kun nämä pyörteet kulkeutuvat kapeikon läpi, mikä voi olla pelkkä muutos henkitorven poikkipinta-alassa, osa pyörteen liike-energiasta muuttuu akustiseksi häiriöksi. Tämän lisäksi kirjallisuuskatsauksessa tutkittiin epätavallisten trakeasta kuultavien hengitysäänten syntyä. Avoimen, osittain ahtautuneen ja kokonaan ahtautuneen hengitystien tapaukset tarkasteltiin erikseen Sterling-vastusmallin avulla. Kuorsausta ja kudosvärinää havaittiin tilanteessa, jolloin hengitystie oli osittain ahtautunut. Pirkanmaan sairaanhoitopiirin unilaboratoriossa käytetylle trakeaäänien rekisteröintilaitteistolle tehtiin laatumittauksia. Mittauksissa havaittiin, että mikrofonissa oli hieman harmonista vääristymää ja käytetyn äänikortin taajuusvaste ei ollut suora, kun näytteenottotaajuutena oli 11kHz. Yhteenvetona voidaan sanoa, että eri tutkimusryhmien tulisi käyttää laadultaan korkeatasoisia mittalaitteita, kun trakeasta kuuluvia hengitysääniä rekisteröidään. Jos näin toimittaisiin, korkealaatuinen trakea-hengitysääni voisi tuoda uutta tietoa unen hengitysfysiologiaan liittyen. Nykyisessä tilanteessa eri tutkimusryhmien mittaukset eivät ole täysin vertailukelpoisia keskenään ja tämän vuoksi tieteellistä luotettavuutta on vaikea saavuttaa

Aerospace Medicine and Biology: A continuing bibliography with indexes (supplement 141)

This special bibliography lists 267 reports, articles, and other documents introduced into the NASA scientific and technical information system in April 1975

Assessment of graded changes in the central nervous system, during general anaesthesia and surgery in man, using the auditory evoked response

The thesis examines the use of the auditory evoked response (AER) to measure 'depth of anaesthesia'. The historical background to general anaesthesia is reviewed. Developments in recording the evoked responses with particular reference to the auditory evoked response and the factors which influence this are described. The effects of increasing concentrations of six general anaesthetic agents (halothane, enflurane, isoflurane, etomidate, Althesin and propofol) on the brainstem and early cortical auditory evoked responses and the modification of these effects by surgical stimulation were investigated. The AER as an indicator of 'awareness' was also assessed. These studies showed that all six general anaesthetics produced qualitatively similar changes in the early cortical section of the AER. These were increases in latency and reductions in amplitude of the waves Pa and Nb with increasing concentrations of anaesthetics. The amplitude changes were partially reversed during surgery. Only the inhalation anaesthetics (halothane, enflurane and isoflurane) produced changes in the brainstem response. The latencies of waves III and V and their interpeak intervals increased with increasing anaesthetic concentrations. These changes were not reversed during surgery. The latency of the early cortical wave Nb, emerged as a possible indicator of 'awareness' in that, in a group of patients anaesthetised with nitrous oxide and oxygen prior to general surgery, latencies below 44.5 ms were associated with a positive response using the isolated forearm technique. In a second study,during Caesarian section surgery, latencies below 44.5 ms occurred more frequently following delivery in patients in whom anaesthesia was maintained with nitrous oxide-opiate anaesthesia only, compared to those to whom an enflurane supplement was given. These findings and their theoretical implications are examined in the light of the literature. The practical application of the technique as a clinical monitor of anaesthetic depth is discussed

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 144

This bibliography lists 257 reports, articles, and other documents introduced into the NASA scientific and technical information system in July 1975

Models and Analysis of Vocal Emissions for Biomedical Applications

The MAVEBA Workshop proceedings, held on a biannual basis, collect the scientific papers presented both as oral and poster contributions, during the conference. The main subjects are: development of theoretical and mechanical models as an aid to the study of main phonatory dysfunctions, as well as the biomedical engineering methods for the analysis of voice signals and images, as a support to clinical diagnosis and classification of vocal pathologies

Models and Analysis of Vocal Emissions for Biomedical Applications

The MAVEBA Workshop proceedings, held on a biannual basis, collect the scientific papers presented both as oral and poster contributions, during the conference. The main subjects are: development of theoretical and mechanical models as an aid to the study of main phonatory dysfunctions, as well as the biomedical engineering methods for the analysis of voice signals and images, as a support to clinical diagnosis and classification of vocal pathologies