The mission is to carry out basic, applied and translational research in biomedical engineering.

Cardiovascular and Respiratory System Research

Respiratory Sinus Arrhythmia Component Extraction by Combining LMS and PCA Derived Respiration. Respiratory sinus arrhythmia (RSA) is a phenomenon where the heart rate changes synchronously with respiration. We devised a method to produce ECG derived surrogate respiration that can be used as a reference signal in an LMS adaptive filter to extract the RSA component from cardiovascular signals. A surrogate respiration signal is obtained by principal component analysis applied to QRS complexes. A method minimizing residual energy is used to select an optimal PC component for the surrogate. Results indicate that one PC is adequate as respiration reference for the adaptive filter and that the ECG-based surrogate produces comparable results to the actual respiration signal.

Continuous Assessment of Nasal Airflow Resistance by Adaptive Modelling. A method to assess nasal airflow resistance was introduced that provides a continuous resistance value, and applies a novel minimally obtrusive measurement technique. The continuous pressure recording is produced with a nasopharyngeal catheter inserted 8 cm deep along the floor of one nasal cavity and the flow recording is produced with respiratory effort bands. A least-mean-square (LMS) extension for the resistance model by Broms is developed that dynamically adapts to the time-varying characteristics of the nasal functioning, and produces the continuous resistance values. Experimental results are shown that demonstrate the uniqueness and applicability of the new technique in assessing the differences between normal and symptomatic patients, and the effect of nasal treatment on patients.

Central Nervous System Research

Electroencephalogram-based depth of anaesthesia measurement. Increasing concentrations of anaesthetics in the blood induce a continuum of neurophysiological changes, which reflect on the EEG. A novel method was developed to estimate the phase of the continuum using the feature data extracted from the EEG. In the method, the feature data calculated from EEG sequences corresponding to continuously deepening anaesthesia are considered to form a one-dimensional nonlinear manifold in the multidimensional feature space. Utilizing a recently proposed algorithm, Isomap, the dimensionality of the feature data is reduced to achieve a one-dimensional embedding, representing this manifold, and thereby the continuum of neurophysiological changes during induction of anaesthesia. The proposed method provides a novel approach assessing neurophysiological changes during anaesthesia and offers potential for the development of more advanced systems for the depth of anaesthesia monitoring.

Usually, general anaesthesia is induced with a combination of drugs. In addition to the hypnotic agent, such as propofol, opioids are often used due to their synergistic hypnotic and analgesic properties. A novel technology for separating the anaesthetic effects of propofol and an ultra-short-acting opioid, remifentanil, using the spectral features of EEG was proposed. Including the detection of the presence of opioids to the estimated effect of propofol significantly improves the determination of the clinical state of the patient.

Musculoskeletal System Research

In our osteoporotic fracture risk study, we have shown that the risk of trochanteric fractures could be discriminated, based on the standard clinical bone mineral density (BMD) based criterion, whereas cervical fracture cases would remain under-diagnosed if solely using this criterion. Instead, geometrical risk factors are able to discriminate cervical fracture cases even among individuals with high BMD. We also showed that dual-energy digital radiography (DEDR) can be applied for the assessment of bone density. In future, combining BMD measurements using DEDR with structural and geometrical information available on digital radiographs could enable a more comprehensive assessment of bone.

Using the finite element method, we analysed the principal strain distributions, and computed the strain ratio for strain patterns over the cervical and trochanteric regions. Using this novel methodology, we were able to predict the hip fracture type with an accuracy of 85%.

Using the accelerometer-based technology, we have now developed a novel index DIS (Daily Impact Score) for assessing the osteogenic response of daily physical activity. A patent application was filed on the new method. In future, we will test if a similar index can be developed for assessing the response of exercise to other health outcomes as well, like osteoarthritis, glucose tolerance etc. We performed a joint bone exercise study in Sendai, Japan, that is now finished and the results have been published. Using our physical activity measurement technology, we were able to show that even a short exercise session during the working day has positive effects for bone, if the intensity of exercise is high.

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Personnel

 

External Funding

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Selected Publications

Ahola R, Korpelainen R, Vainionpää A & Jämsä T (2010) Daily impact score in long-term acceleration measurements of high-impact exercise. J Biomech 43(10): 1960-1964.

Finnilä M, Zioupos P, Herlin M, Miettinen HM, Simanainen U, Håkansson H, Tuukkanen J, Viluksela M & Jämsä T (2010) Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure on bone material properties. J Biomech 43(6): 1097-1103.

Heikkinen J, Jansson-Verkasalo E, Toivanen J, Suominen K, Väyrynen E, Moilanen I & Seppänen T (2010) Perception of basic emotions from speech prosody in adolescents with Asperger syndrome Logopedics Phoniatrics Vocology, 35(3): 113-120.

Herlin M, Kalantari F, Stern N, Sans D, Larsson S, Viluksela M, Tuomisto JT, Tuomisto J, Tuukkanen J, Jämsä T, Lind PM & Håkansson H (2010) Quantitative characterization of changes in bone geometry, mineral density and biomechanical properties in two rat strains with different Ah-receptor structure after long-term exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin. Toxicology 273(1-3): 1-11.

Hyytinen-Oinas MK, Ylitalo K, Karsikas M, Seppänen T, Raatikainen MJ, Uusimaa P, Huikuri HV & Perkiömäki JS (2010) Electrocardiographic abnormalities and ventricular tachyarrhythmias after myocardial infarction. Scandinavian Cardiovascular Journal, May 28, Epub ahead: 1-9.

Isojärvi H, Keinänen-Kiukaanniemi S, Kallio M, Kaikkonen K, Jämsä T, Korpelainen R (2010) Serum triglycerides, fitness and physical activity are associated to peripheral nervous system function in overweight adults. Med Sci Sports Exerc 42(7): 1241-1245.

Karjalainen T, Göransson H, Viinikainen A, Jämsä T & Ryhänen J (2010) Nickel-titanium wire as a flexor tendon suture material. An ex vivo study. J Hand Surg Eur 35(6): 469-744.

Kenttä T, Karsikas M, Junttila J, Perkiömäki J, Seppänen T, Kiviniemi A, Nieminen T, Lehtimäki T, Nikus K, Lehtinen R, Viik J, Kähönen M & Huikuri H (2010) QRS-T morphology measured from exercise electrocardiogram as a predictor of cardiac mortality. Europace, in print. On-line doi: 10.1093/europace/euq461.

Kiviniemi A, Tiinanen S, Hautala A, Seppänen T, Norton K, Frances M, Nolan R, Huikuri H, Tulppo M & Shoemaker J (2010) Low-frequency oscillations in R-R interval and blood pressure across the continuum of cardiovascular risk. Autonomic Neuroscience: Basic and Clinical 158(1-2): 92-99.

Kiviniemi A, Tiinanen S, Huikuri H, Hautala A, Seppänen T, Mäkikallio T & Tulppo M (2010) Frequency of slow oscillations in arterial pressure and R-R intervals during muscle metaboreflex activation. Autonomic Neuroscience 152(1-2): 88-95.

Koivumäki J, Thevenot J, Pulkkinen P, Salmi JA, Kuhn V, Lochmüller EM, Link TM, Eckstein F & Jämsä T (2010) Association of strain distribution with the occurrence of cervical vs. trochanteric hip fractures. Med Biol Eng Comput 48: 711-717.

Korpelainen R, Keinänen-Kiukaanniemi S, Nieminen P, Heikkinen J, Väänänen K & Korpelainen J (2010) Long-term outcomes of exercise: follow-up of a randomized trial in older women with osteopenia. Arch Intern Med. 170(17): 1548-1556.

Kortelainen J, Väyrynen E, Seppänen T (2010) Isomap approach to EEG-based assessment of neurophysiological changes during anesthesia. IEEE Transactions on Neural Systems and Rehabilitation Engineering, In press. DOI: 10.1109/TNSRE.2010.2098420.

Niu KJ, Heikkinen R, Guo H, Korpelainen R, Uchimaru J, Vainionpää A, Sato K, Sakai A, Salo S, Komatsu S, Jämsä T & Nagatomi R (2010) Effect of office-based high-impact exercise on bone mineral density in healthy premenopausal women: The Sendai Bone Health Concept Study. J Bone Miner Metab 28(5): 568-577.

Pulkkinen P, Partanen J, Jalovaara P & Jämsä T (2010) BMD T-score discriminates trochanteric fractures from unfractured controls, whereas geometry discriminates cervical fracture cases from unfractured controls of similar BMD. Osteopor Int 21(7):1269-1276.

Rantalainen T, Nikander R, Heinonen A, Multanen J, Häkkinen A, Jämsä T, Kiviranta I, Linnamo V, Komi PV & Sievänen H (2010) Neuromuscular performance and body mass as indeces of bone loading in premenopausal and postmenopausal women. Bone 46: 964-969.

Rantanen A, Laukka S, Lehtihalmes M & Seppänen T (2010) Heart rate variability (HRV) reflecting from oral reports of negative experience. Procedia Social and Behavioral Sciences, 5:483-487.

Seppänen T, Koskinen M, Seppänen TM & Alho O-P (2010) Addendum to ‘Continuous assessment of nasal airflow resistance by adaptive modeling’ technical repeatability. Physiol Meas 31: 1547-1551.

Seydou F & Seppänen T (2010) Recovery of potential singularities in ultrasound imaging. International Review of Physics, October.
Tahvanainen PS, Lammentausta E, Pulkkinen P, Tervonen O, Jämsä T & Nieminen MT (2010) Dual-energy digital radiography for the assessment of bone mineral density. Acta Radiol 51(5): 543-548.

Thevenot J, Pulkkinen P, Kuhn V, Eckstein F & Jämsä T (2010) Bilateral asymmetries in hip related to experimental fracture type. Calcif Tissue Int 87: 203-210.

Tölli H, Kujala S, Levonen K, Jämsä T & Jalovaara P (2010) Bioglass as a carrier for reindeer bone protein extract in the healing of rat femur defect. J Mater Sci Mater Med 21(5): 1677-1684.

Väyrynen E, Toivanen J & Seppänen T (2010) Classification of emotion in spoken Finnish using vowel-length segments: Increasing reliability with a fusion technique. Speech Communication, doi:10.1016/j.specom.2010.09.007.