CC BY
18UDC 612.173; 517.988
ENTROPY MONITORING IN MEDICINE
Mohammad Omer, G.M. Amanbaeva International Higher School of Medicine, Bishkek, Kyrgyzstan
Abstract
Entropy is a basic concept of physics, with analogues in communication theory and other fields. We review applications of entropy in medical research, under the Entropy measurement is to be used as an adjunct to other physiological parameters. With Entropy used together with other monitored parameters, such as the hemodynamic measurements andNMT, you can get a complete picture of the patient status combined on one screen. Entropy is a measure of irregularity in any signal. The Entropy Module measures these changes by quantifying the irregularity of EEG and FEMG signals. Titration of anesthetics to Entropy Guideline should be done in context of patient status and treatment plan. In the current paper we describe uses of entropy in medical research.
Keywords: entropy, entropy monitoring, EEG, ECG, frequency.
Introduction
In science, the term 'entropy' was introduced by Clausius in 1865, meaning a ratio of heat to temperature, denoted S. According to the second law of thermodynamics, heat flows spontaneously from hot bodies to cold ones, and not the reverse, and this implies that S always increases. In 1877, Boltzmann used a molecular approach to derive an equivalent form, which depends on the number W of microscopic states consistent with the macroscopic state of a system: S=klog(W), where k is Boltzmann's constant.
Entropy is a measure of disorder or randomness or the tendency of a system to move toward randomness. Diminished capacity for spontaneous change, as occurs in the psyche in aging [ 1 ]. It is used in adult and pediatric patients > 2 years to monitor the state of the brain by data acquisition of electroencephalograph (EEG) and frontal electromyography (FEMG) signals. The spectral entropies, Response Entropy (RE) and State Entropy (SE), are processed EEG and FEMG variables.
In adult patients, Response Entropy (RE) and State Entropy (SE) may be used to monitor the effects of certain anesthetic agents, which may help the user to titrate anesthetic drugs according to the individual
needs of adult patients. Furthermore, in adults, the use of Entropy parameters may be associated with a reduction of anesthetic use and faster emergence from anesthesia. The Entropy measurement is to be used as an adjunct to other physiological parameters [2].
Now we will consider the application to medical research of a physical principle which is based on a concept closely linked to that of entropy.
Entropy Monitoring
Entropy is a measure of irregularity in any signal. During general anesthesia, EEG changes from irregular to more regular patterns as anesthesia deepens. Similarly, FEMG quiets down as the deeper parts of the brain are increasingly saturated with anesthetics. The Entropy Module measures these changes by quantifying the irregularity of EEG and FEMG signals.
The Entropy parameters in EEG:
There are two Entropy parameters: the fast-reacting Response Entropy (RE) and the State Entropy (SE). State Entropy consists of the entropy of the EEG signal calculated up to 32 Hz while Response Entropy includes high frequencies up to 47Hz. Consequently, the fast frontal EMG (FEMG) signals
Address for Correspondence: Mohammad Omer Is' year student of Medical Faculty of ERPC "International University of Kyrgyzstan " email :m. omer959(a),hotmail. com
enable a fast response time for RE. Parameter Frequency rate
Display range Response Entropy, RE0.8 < f < 47 Hz 0-100
State Entropy, SE 0.8 < f< 32 Hz 0 - 91
Response Entropy (display range 0-100):
Response Entropy is sensitive to the activation of facial muscles, (i.e., FEMG). Its response time is very fast; < 2 seconds. FEMG is especially active during the awake state but may also activate during surgery. Facial muscles may also give an early indication of emergence, and this can be seen as a quick rise in RE.
State Entropy (display range 0 - 91): The State Entropy value is always < Response Entropy. During general anesthesia, the hypnotic effect of certain
anesthetic drugs on the brain may be estimated by State Entropy value. SE is less affected by sudden reactions to the facial muscles because it is mostly based on the EEG signal. Neuromuscular blocking agents (NMBA), administered in surgically appropriate doses are not known to affect the EEG, but are known to have an effect on the EMG.
Entropy monitoring is used to titrate anesthetic drugs based on individual patient needs
Use Entropy monitoring helps to control recovery and improve preoperative process Integrated information. With entropy used together with other monitored parameters, such as the hemodynamic measurements gives a full picture of the patient status combined on one screen. All the values are stored for trending and information management purposes.
Example:
Each anesthetic drug has its own EEG signature that reflects its site of action [3]: Propofol acts at the GABA receptor and has this signature:
Ketamine acts at the NMDA receptor:
Dexmedetomidine acts at the locus coeruleus:
Spindles
Rhythms of EEG in different conditions of entropy monitoring [4]. Normal Waves
Awake with mental activity Beta 14-30 Hz
Awake and resting Alpha 8-13 Hz
Sleeping Theta 4-7 Hz
Deep sleep 1 sec Delta < 3.5 Hz
Waves of an Epileptic patient [5]
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The examples of pathological superimposed transients (SITs) of interictal epileptic discharges (IED) seen in canine epilepsy patients.
A. Spike activity (arrows) in C3, C4 leads. In monopolar montage the amplitudes in C3, C4 are the highest, in bipolar a reversed polarity is seen (spikes
directed towards each other, (arrows)).
B. Poly-spikes activity (arrows) significantly stand out from the background activity (BGA). Due to Entropy, we can differentiate between ordered and disordered Waves/Rhythms and its spikes.
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Entropy in ECG [6], a typical ECG waveform shown below describes a series of waves that are labelled asP, Q, R, S and T. P wave is followed by QRS complex and then a trailing T wave.
> The P wave reflects atrial depolarization
> Q, R, and S waves represent the ventricular depolarization
> Hie T wave corresponds to Ventricular repolarization
> The U wave is of indeterminate origin
> The ECG has a frequency range is 0.05Hz -100 Hz
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ECG signal as shown below from a normal healthy individual Arterial Fibrillation (AF): is a result of multiple activations, sweeping around the atrial
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myocardium. The AF represents absence of P waves. Instead of P waves, fibrilliform "F" waves with a rate higher than 350 bpm are present. The interval between successive QRS complexes is not constant. A typical AF waveform is as below. Based on the frequency of the QRS complexes, AF canbe differentiated from Bradycardia or Tachycardia.
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Congestive Heart Failure (CHF): is a condition in which the heart muscle is not strong enough, to pump sufficient oxygen-rich blood to the body. Insufficient pumping of the blood from the heart
Conclusion
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Entropy, which Shaip spotlights on in a biomedical framework, drives the bearing of all concoction responses towards scatter. This ground-breaking procedure has a few preferences over choices, for example, GARP, and is effectively accessible through the product made openly accessible by the creators. With Entropy we can tell if the individual is in Bradycardia, tachycardia, have a tumor, an aneurysm or some other perilous well-being conditions.
References
1. About Entropy, (n.d.) Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. (2003). Retrieved from https.'//medical dictionary.thefreedictionary.corn/About+Entropy
2. GEHealthcare. Entropy, GEHealthcare, 2016, www.gehealthcare.co.uk/-/jssmedia/76841dd076a54dd5blaa26e21cl0e4cf.pdf?la= en-gb.
3. Assessing approachesfor brain function monitoring. (2017,
August 22). Medscape.
https://www.medscape.org/viewarticle/857986_transcript
4. Abhang, Priyanka, and Dr. Bharti WGawali. "Fig. 4. EEG
Waves for Different Signals." ResearchGate, 1 Aug. 2018, www, researchgate. net/figure/EEG-waves-for-different-
leads to the accumulation of the fluid in the lungs and other organs. CHF is most common in elderly of age > 70 years [6].
signals_fig4_281801676.
5. The examples of pathological superimposed transients (SITs) of... (2018, August 1). ResearchGate. https://www, researchgate. net/iigure/The-examples-of-pathological- superimposed-transients-SITs-of-interictal-epileptic_fig4_303888312
6. Application of entropy techniques in analyzing heart rate variability using ECG signals, (n.d.). ResearchGate. https://www.researchgate.net/publication/331062390_Ap
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