Delta Entropy of Heart Rate Variability Along with Deepening Anesthesia

• Published in: Anesthesia and analgesia Vol. 112; no. 3; pp. 587 - 592
• Main Authors: Mäenpää, Mika, Laitio, Timo, Kuusela, Tom, Penttilä, Jani, Kaisti, Kaike, Aalto, Sargo, Hinkka-Yli-Salomäki, Susanna, Scheinin, Harry
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD International Anesthesia Research Society 01.03.2011; Lippincott Williams & Wilkins
• Subjects: Adult; Anesthesia; Anesthesia - adverse effects; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Biological and medical sciences; Delta Rhythm - drug effects; Delta Rhythm - physiology; Electrocardiography - drug effects; Electrocardiography - methods; Entropy; Heart Rate - drug effects; Heart Rate - physiology; Humans; Male; Medical sciences; Methyl Ethers - adverse effects; Monitoring, Intraoperative - methods; Propofol - adverse effects; Young Adult; Heart rate; Anesthesia; Entropy; Variability
• ISSN: 0003-2999; 1526-7598; 1526-7598
• DOI: 10.1213/ANE.0b013e318208074d

Conventional time and frequency domain measures of heart rate variability (HRV) are strongly influenced by anesthetic drugs, and are therefore not able to detect subtle changes in HRV, even during light anesthesia. Approximate entropy of R-R intervals is an HRV measure that has a tendency to decrease during anesthesia, but it is severely compromised by low-frequency variations of the signal. However, the negative effect of the low-frequency variations can be eliminated by differentiating the R-R interval tachogram before analysis. We designed this study to investigate characteristics of a novel HRV measure, named δ entropy (dEn), during deepening anesthesia. Eight healthy subjects were anesthetized with sevoflurane and 8 with propofol in a stepwise manner using 3 escalating concentrations (2%, 3%, and 4% end-tidal concentration and 7.4 ± 1.7, 12.3 ± 2.6, and 18.3 ± 5.0 μg/mL plasma concentration, respectively) at 30-minute intervals. A third group of 8 subjects received a supramaximal IV dose of glycopyrrolate without anesthesia to examine the effect of cardiac vagal activity on dEn. We computed dEn at baseline, during each step of anesthesia and during the anticholinergic blockade. The dEn decreased along with deepening levels of sevoflurane and propofol anesthesia up to 33% (95% confidence interval [CI] 21%-44%) and 38% (95% CI 28%-48%), respectively. At each anesthesia level, dEn differed significantly (P < 0.05) from that measured at the preceding level, similarly in both the sevoflurane and propofol groups. Parasympathetic blockade by glycopyrrolate was found to decrease dEn by 17% (95% CI 6%-28%). The dEn is a novel HRV measure able to detect subtle sympathetic- and parasympathetic-mediated alterations in HRV both during deepening levels of sevoflurane and propofol anesthesia and during exceedingly deep anesthesia.