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Cardiology Research and Practice
Volume 2018, Article ID 1590217, 8 pages
https://doi.org/10.1155/2018/1590217
Research Article

Increases in Heart Rate Variability Signal Improved Outcomes in Rapid Response Team Consultations: A Cohort Study

1Department of Critical Care Medicine, King Faisal Specialist Hospital & Research Centre, Riyadh 11211, Saudi Arabia
2Section of Electrophysiology, Heart Center, King Faisal Specialist Hospital & Research Centre, Riyadh 11211, Saudi Arabia
3College of Medicine, Alfaisal University, P.O. Box 50927, Riyadh 11533, Saudi Arabia
4Department of Critical Care Medicine, king Faisal Specialist Hospital & Research Centre, Riyadh 11211, Saudi Arabia
5Department of Nursing, King Faisal Specialist Hospital & Research Centre, Riyadh 11211, Saudi Arabia
6National Biotechnology Center, King Faisal Specialist Hospital & Research Centre, Riyadh 11211, Saudi Arabia

Correspondence should be addressed to Nawal Salahuddin; moc.liamg@lawan.nidduhalas

Received 16 September 2017; Revised 17 December 2017; Accepted 28 December 2017; Published 1 March 2018

Academic Editor: Senol Dane

Copyright © 2018 Nawal Salahuddin et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background. Reduced heart rate variability (HRV) indicates dominance of the sympathetic system and a state of “physiologic stress.” We postulated that, in patients with critical illness, increases in HRV might signal successful resuscitation and improved prognosis. Methods. We carried out a prospective observational study of HRV on all patients referred to the rapid response team (RRT) and correlated with serial vital signs, lactate clearance, ICU admission, and mortality. Results. Ninety-one patients were studied. Significantly higher HRV was observed in patients who achieved physiological stability and did not need ICU admission: ASDNN 19 versus 34.5, ; rMSSD 13.5 versus 25, ; mean VLF 9.4 versus 17, ; mean LF 5.8 versus 12.4, ; and mean HF 4.7 versus 10.5, . ROC curves confirmed the change in very low frequencies at 2 hours as a strong predictor for ICU admission with an AUC of 0.772 (95% CI 0.633, 0.911, ) and a cutoff value of −0.65 associated with a sensitivity of 78.6% and a specificity of 61%. Conclusions. Reduced HRV, specifically VLF, appears closely related to greater severity of critical illness, identifies unsuccessful resuscitation, and can be used to identify consultations that need early ICU admission.