Open Access e-Journal Cardiometry No.16 May 2020
We should mention that Cardiometry is a fine diagnostics tool to assess heart life expectancy. Our experts, using Cardiocode in “red zones” in intensive care units, have confirmed effectiveness of noninvasive measuring of the hemodynamics data on the cardiovascular system performance in critical patients with different severity degrees. The medical staff involved had a possibility not only to monitor the state in each critical patient, but also to predict and control the progression of a disease. We are going to publish some results of this pilot study in our next issues. We should mention that Cardiometry is a fine diagnostics tool to assess heart life expectancy. Our experts, using Cardiocode in “red zones” in intensive care units, have confirmed effectiveness of noninvasive measuring of the hemodynamics data on the cardiovascular system performance in critical patients with different severity degrees. The medical staff involved had a possibility not only to monitor the state in each critical patient, but also to predict and control the progression of a disease. We are going to publish some results of this pilot study in our next issues.
Figure 1. Pulse shape in “smart biphasic pulse» at a load of 25,50, 100 and 125 ohmsFigure 2. Diagram of "an adaptive biphasic pulse" at a load of25, 50, 100, 125 ohmsFigure 3. Diagram of the SCOPE pulse at a load of 25, 50 and100 ohmsFigure 4. Diagram of “an orbital” pulse with an energy of 200 Jat a load of 25, 50, 100, 125 ohmsFigure 4 shows that the signals are characterized bya prolonged pulse duration (up to 35 ms with a highresistance). Previously it was assumed that it was impossibleto efficiently use the technology in patientshaving a high resistance. However, some studies in animalshave demonstrated the opposite. Studied were 6dogs weighing 21.6 to 34.5 kg, and it was found thatthe defibrillation threshold was from 20 to 30 J, whichwas comparable with the biphasic defibrillator with avoltage of 2 kV. Patients with a high resistance weremodeled with an additional resistor of 32 ohms, thethreshold defibrillation rose to 34.3 J. Despite the obtainedresults, which are not typical to humans, developersbelieve that the orbital biphasic pulses may beapplicable to humans.Figure 5 gives a "multipulse" discharge type, whichdemonstrates a feature to represent each phase in theform of pulses with a frequency of 5 kHz and a pulse/pause ratio of 1: 1. Finally, the single-phase pulse studieshave shown that such pulses behave as a closed signalof a medium current strength [19,20]. As is known,the pulse energy depends on the square of the current,and a pulse interruption leads to an increase in energyrequirements. This is compensated by the fact that thedeclared pulse duration is closer to the minimum necessaryfor the cardiomyocytes excitation, in comparisonwith the biphasic pulse shapes as discussed above.Figure 5 gives an illustration of fundamental differencesbetween the "multipulse" discharge from thepreviously described discharge techniques, but in factthis is a standard bipolar exponentially truncated signal.The protocol of the energy increase recommendedby the developers implies starting with 90 J and maximizingup to 180 J. The energy of 180 J is positioned asa "threefold energy margin”.Used is the so-called STAR discharge which representsa biphasic pulse. It has long been consideredto be optimal from the standpoint of the structure ofthe second phase, which consequently implementsthe theory of "a charge balance". The patents describea debatable discrete equivalent circuit diagram andsome findings associated therewith [21,22]. Impedanceis mentioned as an additional feature, althoughits importance cannot be underestimated [23]. Thesefacts do not allow us considering the "STAR pulse” asa relevant pulse circuitry.As a “linear” pulse described is a pulse, which inthe first phase is close to a rectangular pulse with aconstant current of 15A. It is emphasized that the timeis constant for any allowable resistance. This is sup-82 | Cardiometry | Issue 16. May 2020
Figure 5. Diagram of “a multipulse” signal with an energy of 200 Jat a load of 25 and 100 ohmsFigure 6. Diagram of “a linear” pulse with an energy of 200 J ata load of 25, 50, 100 and 125 ohmsFigure 7. Diagram of “a biphasic” pulse at a load of 25, 50, 100and 125 ohmsported by the results of the pulse test, presented in Figure6 herein.Thanks to the constant current density the efficacyconsiderably increases, especially in the patients witha low resistance. The patients with a high resistance,in their turn, are exposed to a standard bipolar pulse,which is relatively shorter than the above one. Fromthe standpoint of engineering, the pulse shaping isprovided with the use of serially connected resistors,the required set of which is switched depending onthe patient’s actual impedance [24]. An imperfectionof this circuit is a high voltage, when discharging tolow resistance, despite the stated CCT system.The "biphasic" pulse peculiarity is a programmableswitch, which allows changing the ratios of the deliveredenergy. In the design settings, the developers preset theratio of energies as 90% in the first and the remaining10% in the second phase. When testing the signal, thefirst pulse duration always is 4 ms, which is the optimaltime to complete repolarization according to numerousstudies [15]. As it is the case with the previous signal,this can be realized at high voltage charging only. Diagramsof pulse with an energy of 200 J at a load of 25,50, 100 and 125 ohms are given in Figure 7 herein.ConclusionsConsidering the conducted analysis of the existing developmentsin the field of external defibrillation, theapplicable recommendations on cardiopulmonary resuscitation,and the results of the theoretical research,we may arrive at conclusions as follows:1. Optimal is the biphasic pulse of rectangular shape,that provides a constant current density of 14 -16 A,delivered in 4 -5 ms. The maintenance of these parameterscan be achieved using the current stabilizationtechnology.2. According to the recommendations, the startingcharge for adults is 150 J, with a possibility of increasingit up to 360J. The conducted studies on the presentedbiphasic pulses demonstrate the possibility of achievinggeneral repolarization with lower values of energy,but it is necessary to have an engineering solution todeliver the maximum energy of 360J.3. The ratios between the first phase and the secondphase of the pulses in external biphasic defibrillatorsunder consideration show significant differences, butall of them have been implemented in clinically approveddefibrillators. So, we can conclude that the issueon the ratio between the phases remains on the agendaas a subject for further research.Statement on ethical issuesResearch involving people and/or animals is in fullcompliance with current national and internationalethical standards.Conflict of interestNone declared.Author contributionsThe authors read the ICMJE criteria for authorship andapproved the final manuscript.Issue 16. May 2020 | Cardiometry | 83
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Figure 5. Diagram of “a multipulse” signal with an energy of 200 J
at a load of 25 and 100 ohms
Figure 6. Diagram of “a linear” pulse with an energy of 200 J at
a load of 25, 50, 100 and 125 ohms
Figure 7. Diagram of “a biphasic” pulse at a load of 25, 50, 100
and 125 ohms
ported by the results of the pulse test, presented in Figure
6 herein.
Thanks to the constant current density the efficacy
considerably increases, especially in the patients with
a low resistance. The patients with a high resistance,
in their turn, are exposed to a standard bipolar pulse,
which is relatively shorter than the above one. From
the standpoint of engineering, the pulse shaping is
provided with the use of serially connected resistors,
the required set of which is switched depending on
the patient’s actual impedance [24]. An imperfection
of this circuit is a high voltage, when discharging to
low resistance, despite the stated CCT system.
The "biphasic" pulse peculiarity is a programmable
switch, which allows changing the ratios of the delivered
energy. In the design settings, the developers preset the
ratio of energies as 90% in the first and the remaining
10% in the second phase. When testing the signal, the
first pulse duration always is 4 ms, which is the optimal
time to complete repolarization according to numerous
studies [15]. As it is the case with the previous signal,
this can be realized at high voltage charging only. Diagrams
of pulse with an energy of 200 J at a load of 25,
50, 100 and 125 ohms are given in Figure 7 herein.
Conclusions
Considering the conducted analysis of the existing developments
in the field of external defibrillation, the
applicable recommendations on cardiopulmonary resuscitation,
and the results of the theoretical research,
we may arrive at conclusions as follows:
1. Optimal is the biphasic pulse of rectangular shape,
that provides a constant current density of 14 -16 A,
delivered in 4 -5 ms. The maintenance of these parameters
can be achieved using the current stabilization
technology.
2. According to the recommendations, the starting
charge for adults is 150 J, with a possibility of increasing
it up to 360J. The conducted studies on the presented
biphasic pulses demonstrate the possibility of achieving
general repolarization with lower values of energy,
but it is necessary to have an engineering solution to
deliver the maximum energy of 360J.
3. The ratios between the first phase and the second
phase of the pulses in external biphasic defibrillators
under consideration show significant differences, but
all of them have been implemented in clinically approved
defibrillators. So, we can conclude that the issue
on the ratio between the phases remains on the agenda
as a subject for further research.
Statement on ethical issues
Research involving people and/or animals is in full
compliance with current national and international
ethical standards.
Conflict of interest
None declared.
Author contributions
The authors read the ICMJE criteria for authorship and
approved the final manuscript.
Issue 16. May 2020 | Cardiometry | 83
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