Development of sirs depresses heart rate variability

Abstract

43 Development of sirs depresses heart rate variability Naoki Matsumaru , Kunihiro Shirai , Yoko Kawamura , Yasunari Yokota , Keisuke Kumada , Shinji Ogura a Advanced Critical Care Center, Gifu University Hospital, Gifu, Japan Department of Information Science, Faculty of Engineering, Gifu University, Gifu, Japan Objectives: Heart rate variability (HRV) has been investigated as a noninvasive diagnostic for the onset of sepsis. Because the development of a systemic inflammatory response syndrome (SIRS) has been considered a sign of sepsis, we compared HRV values of the intensive care unit (ICU) patients depending on the SIRS state. Methods: From the bedside monitoring system, vital data of patients admitted in ICU were downloaded. Sampling rate of electrocardiogram data is 500 Hz, and HRV is calculated from that. Abnormal heartbeats and trends were eliminated using a stochastic model as described in (IFMBE Proc 2011;35:552–555), and the power spectrum is derived using autoregressive model. As an estimate of HRV, we used the integral value within 0.04 and 0.4 Hz. Vital signs regarding SIRS criteria, that is, heart rate, respiration rate, and core temperature, are recorded every 10 seconds, 0.1 Hz.We arranged the data frequency of HRV value and vital data to be 0.017 Hz (1 data per minute). For every minute, the state of the patients either SIRS positive or negative can be determined, excluding the white blood cell counts. Thus, HRV values can be categorized as SIRS positive or negative. To calculate HRV values for each patient in the state of SIRS positive and negative, we took the median of those categorized, respectively, for the whole term of ICU stay. Statistical tests used IBM SPSS ver. 19 (SPSS, Chicago, Ill). Results: The number of patients registered was 49, and the average length of ICU stay was 31.4 days, ranging from 3 to 113 days. The average age of those patients was 64.3 years. There was no specific disease as registration criteria, but 34 patients of 49 had sepsis. According to Wilcoxon signed rank test with the sample size of 49, difference between the HRV values for SIRS positive vs negative is significant (P b .05). The HRV value for SIRS positive is approximately 2.2% lower than that for SIRS negative on average. In 61.2% of patients, the difference is less than 10%. The percentage of patients to show higher HRV for SIRS positive than that for negative was only 20.4%. Conclusions: Our analysis shows that the HRV value will decrease when a SIRS develops in ICU patients, consistent with previous results (Nihon Rinsho. 2004 Dec;62(12):2285–90; PLoS ONE. 2009;4:e6642, IFMBE Proc. 2011;35:552–555), reporting a decrease of HRV before sepsis. Such observations require HRV to reduce in association with SIRS development, as shown in this study, because SIRS development has been used as an indication of sepsis occurrence. For the purpose of sepsis diagnostics, however, further investigation is necessary. Our result implies that HRV always decreases as SIRS develops, not only with sepsis. We suggest taking temporal characteristics of decreasing HRV into consideration. Adjusting frequency range targeting particularly to sepsis is another idea. http://dx.doi.org/10.1016/j.jcrc.2012.10.059