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Kristian Solem

Publications and source records attributed to Kristian Solem.

2 recordsLinked to original sources

An efficient method for handling ectopic beats using the heart timing signal.

The problem of analyzing heart rate variability in the presence of ectopic beats is revisited. Based on the integral pulse frequency modulation model and the closely related heart timing signal, a new technique is introduced which corrects for the occasional presence of ectopic beats. The correction technique, which involves the occurrence times of a certain number of beats preceding the ectopic beat, is computationally very efficient. From actual heart rate data, the results show that the new technique is associated with a much lower computational complexity (flops reduced by a factor of about 3000) than the original heart timing technique, while producing similar performance. It is also shown that the power spectrum and related clinical indices obtained by the new technique are more accurately estimated than by other methods.

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An electrocardiogram-based method for early detection of abrupt changes in blood pressure during hemodialysis.

Clinical techniques for early detection of acute hypotension during conventional hemodialysis treatment are lacking, even though intradialytic hypotension is the most common acute complication. In this article, intradialytic hypotension is identified by means of signal analysis of data recorded at two clinics. The database consists of 30 treatments with concurrently acquired signals: the 12-lead electrocardiogram, continuous blood pressure, hematocrit, oxygen saturation, relative blood volume, and important hemodialysis variables. This article presents two characteristics, a heart rate turbulence (HRT) measure called turbulence slope (TS), and the LF/HF ratio, which provide information, at the beginning of hemodialysis treatment, on the patient's propensity to hypotension (TS: p = 0.0038, and LF/HF ratio: p = 0.0028). The authors also present a novel dynamic echocardiography-based method for detecting intradialytic hypotension using complementary information on heart rate variability (HRV) and ectopic beat patterns. These two types of information reflect different mechanisms of cardiac activity. It is essential that both types are used for the detection of hypotension, because HRV analysis is inappropriate when several ectopic beats are present. The proposed dynamic echocardiography-based method offers early identification of the cases with acute intradialytic hypotension of the database.

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