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Figure 1 ecg and haemooxin readings shown by the patient's guardian
All ecgs collect heart telecommunications through electrodes connected to specific parts of the body, with only a few milligrams of heart telecommunications generated by the body, and through electrodes connected to specific positions of the body, they observe the activity of the heart electrical activity from different angles, each of which can be shown and printed as an output channel of the ecg. Each channel represents the difference between the two electrodes or the difference between a particular electrode and the average voltage of several electrodes, and the combination of the electrodes can show more channels than the electrodes. These corridors are generally referred to as “guidelines” (or “channels”), and a 12-conductor ecg device has 12 separate graphic display channels. Based on different applications, the number of conduits can be selected between 1 and 12. The problem is that guidance lines connected to electrodes are sometimes also referred to as conduits, which can be confusing, since ecgs of the 12-conductor (12-channel) require only 10 electrodes (10-line) and therefore carefully judge the “links” used。
In addition to biological signals, most ecgs detect two artificial signals in which an implanted pacemaker (known as a “pacing” signal) is the most important. The pace signal is fairly short, ranging from tens of microseconds to milliseconds, ranging from millimetres to near 1 v. Typically, ecg must simultaneously detect the presence of pace signals to prevent interference with other heart telecommunications. The second artificial signal is used to detect "conductor decomposition", i. E. Poor exposure to electrodes. Many ecgs are required to give warning instructions in case of poor electro-code exposure. For this purpose, the ecg equipment produces a signal to measure resistance between electrodes and humans and thus detect the presence of a guidance line. Measuring signals can be either communication or direct flow or can be used in combination. Some ecgs can also detect the frequency of respiration by analysing resistance when the conductor is released. The decomposition of the conductor should be continuously detected and should not prevent accurate measurements of the heart telecommunications。
Figure 2 shows the ecg's overall functional framework. If ecg is divided into a digitally converted front end (afe) and “the rest” of the data to be analysed, displayed, stored and transmitted, it is easier to understand the ekg requirements for electrons. Afe usually has the same basic requirements, with differences in conductivity, signal authenticity, disturbance inhibition, etc. Depending on the specific functional needs, the “remote” of the system varies widely, with typical features including monitors, hard copy printing, wireless (rf) connections and battery charging。
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Figure 2
Conduit (foster)
One of the most significant characteristics is a lead number, with some ecg having only one lead and others up to 12 lead. Ten electrodes are required for the most commonly used 12-conductor ecg, nine of which are used to collect telecommunications numbers, and the tenth is connected to the right leg (rl) and is driven by ecg circuits to reduce comodular voltage. The nine input electrodes are one electrode each for the left arm (la), one for the right arm (ra) and one for the left leg (ll), and six electrodes (v1-v6) for the front-heart ( chest) area. Each conductor or heart television map represents the difference in voltage between an electrode and another electrode or group of electrodes, and if the electrode is assembled, the average voltage is taken. The average of six lead links to the three electrodes, ra, la and ll, as one side of the difference, is v1-v6 on the other side of the six differentials, respectively. Three leads originate from the difference between the average values of ra, la, ll and each of the other two electrodes. The remaining three guides were measured using ra, la and ll as separate differentials. Six guides based on ra, la and ll contain similar information, but are shown in different ways. Since the information is redundant, there is no need to measure all six conduits, and some channel data can be calculated using dsp data analysis for other corridors。
The 12-link system is the most common but not the only option described here. In addition, the 12 lead ecg may also be used as a 5 lead, 3 lead or 1 lead system. The key is to switch arrays and average circuits when more than one lead is required。
Simulate frontend (afe)
The main function of afe is to digitize the heart telecommunications, which is complex because of the need to suppress the rf signal sources, pace signals, guidance detached detection signals, powerful interferences such as industrial fusion signals and other muscle signals and electronic noise. In addition, the mvolt-class heart telecommunications code may be superimposed on hundreds of mvolts of direct loss transfer voltage voltage combined with inter-channel comodular voltage, which may exceed 1 v. The electrodes connected to the patient's body must not create a shock hazard or interfere with other medical devices connected to the patient. The effective frequency range of ecgs is to some extent related to applications, usually between 0. 05 hz and 100 hz。
Afe's second function is to be able to detect pace signals, guide-link drops, breathing frequencies and patient resistance, and detection takes place simultaneously or almost simultaneously on several corridors. In addition, most ecg equipment needs to be recovered quickly when the heart is defibrillated, but because the defibration of the heart leads to saturation of the front end circuits and the recharge capacity, these convalescent circuits may extend the recovery time。
Afe structure
The afe architecture has a significant systemic impact, and the enhanced architecture described below provides high authenticity within a wider frequency by introducing high-precision, high-speed adc (module/number converter). Capability coupling is not used, but is driven as rl by dac (number/modulator), allowing afe to recover quickly from tremors or radio frequency interference. Digital pace signals allow for the analysis of pace data, thereby reducing erroneous pace-pacing instructions and even detecting defects in the pacemaker or the connective parts. On the other hand, it is important to take into account the expensive meta-devices needed to enhance the system and the high power consumption. In contrast, simplified afes are cheaper and battery life is longer, while other characteristics differ very little。
Enhanced afe and dsp afe: high performance adc (as shown in figure 3) is required to meet ecg test requirements, allowing the quantification of nine electrodes at the same time, with no noise accuracy of up to 20 degrees at 200 ks/s sampling rates. A digital signal processor (dsp) is then used to calculate each conductor signal, to isolate the pace signal, the conductor drop signal and the breathing signal, and to filter out the interference frequency signal. The dsp also calculates the signal strength required for the number/modulator (dac) drive of the rl electrodes. This afe structure requires the level of each channel of the modular/digital conversion (adc) device. There is also a need for buffers to isolate adc sample capacitors and high resistance electrodes. Such programmes, while meeting the measurement indicator requirements, do not meet the cost and cost of most applications。
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Simplified afe: the low end aef series are characterized as single channel, consumption class ecg. The afe of these equipments uses a condensed circuit that binds the input signal to a low-intensity differential amplifier and gives it to adc of 10, 120 s/s sampling rates. Capable coupling circuits can remove the direct loss tunes entered and low-through filter filters can filter the pace signals. The equipment is usually powered by batteries and has only one channel, so there is no co-modular voltage. Typical ecg equipment afe: the circuits used by most ecg equipment are in between. The instrument amplifier (ia) is often used to suppress comodular voltages, eliminate comodular noises such as work frequency interference and provide a buffer for adc sampled capacitors, which can filter pace and drop detection signals and then send them to adc for sampling, digital conversion. In some cases, telecommunication numbers and direct loss are directly converted through a high-precision adc. In other cases, high-transform filters or dacs are used to remove the direct loss tunes so that a typical 12-bit accuracy adc can be used for sampling, digital conversion, as shown in figure 4. Each channel can be equipped with an adc or one adc can be shared across multiple corridors for digital conversion. Re-use of adc causes a small temporal deviation between corridors, and the degree of acceptance depends on the specific application. If a pacemaker signal is to be detected, it can be extracted from a high-through filter, then amplified, then amplified and tested on a comparator circuit。
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Ecg equipment type telemetry ecg
Telemetric ecg systems are used for continuous monitoring of mobile patients in clinical settings. They include an esg and a central station with a wireless (rf) transceiver function to collect and analyse patient monitoring data through wireless reception. Some telemetry systems also provide additional data (e. G., blood oxygen values) that are used to validate treatment effects or adjust treatment options and to warn against potential problems。
Many telemetry systems have only five conduits, and it is difficult to cope with the mobility of patients if they have 12. Typically, patients use equipment for several consecutive days, and therefore more such equipment uses single-use batteries. Other ecgs can also increase telemetry, although “telemetry ecg” refers specifically to mobile units that can be carried within hospitals and send data to local receiving stations. For the design of the system, low utility, low noise and small size are considered key。
Holter guardian
Dr. Newman holt invented a mobile monitor to collect data and upload them to other systems for analysis. Unlike telemetry equipment, these monitors do not require a central receiving station and can be used in the home, outdoors or anywhere else. For holter ecg custodians, because the 12-link monitor cannot move, in most cases the number will not exceed five. Data are generally transferred from the custodian by memory cards and, of course, by usb disk or other means. Most patients only need to be monitored for one or two days, and when the patient is required to participate in certain pharmacological studies, special long-term custody is used, which may take one year or more. The main requirements for the design of the holter ecg monitor are low utility, low noise and small size。
Consumption category ecg
These low-end ecgs can easily be attached to their arms and people can perform ecg checks at home, and these devices can save data and display on-screens. Data can also be transmitted to the rehabilitation centre via computer or telephone lines. Some instruments have multiple electrodes attached, while others have only two electrodes installed on the shell. The inner electrodes can be pressured on the chest or placed on two electrodes. The resulting electrocardiograms, which may not be of good quality, provide an effective way for people to monitor their own situation and collect electrocardiograms in exceptional circumstances. Consumer ekgs are designed primarily for cheap and small sizes。
Automation defibrillator (aed)
Aed equipment is installed mostly in public places (such as shopping malls, gymnasiums and offices) to respond to emergencies in the public sphere. These devices can be used immediately in the event of a heart attack, releasing a high-energy electrical pulse to the chest, and a pacemaker's heart and restoring it to normal heart rate. If used at an inappropriate time, pulse shocks can put life at risk and ecg must therefore be functionally capable of preventing such accidents. Aed generally has only one conductor and its electrodes are used both to release high pressure pulses and to collect heart telecommunications. The rationale for aed equipment is illustrated in figure 5。
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Aed may be put on hold for months or years, and the equipment is often used without professionally trained personnel who are not aware of the equipment, even if it is problematic. When the aed is needed, it is necessary to turn on the engine, perform a series of self-checks to confirm that the functionality is intact, and then run for a short period of time. All electrocardiogram data and defibrillation information need to be recorded for subsequent analysis. The use of problematic aeds outweighs the benefits, so reliability and self-diagnosis are the first considerations in aed design。
Diagnostic ecg
The diagnostic ecg equipment is used in hospitals and doctors ' offices to provide high-quality ecg testing, which can test all of the ecgs and create hard copy output. These devices use high performance afe, which can generally improve ecg detection quality by adjusting the gain and selecting the appropriate filter. Owing to the large size of the equipment, there is space to perform additional functions, such as built-in printers, various communication interfaces, large-scale monitors, etc. They typically use communication power and are usually backed up with chargeable batteries. The key to designing diagnostic ecgs is low noise, high resistance to interference and flexibility。
Patient custody
Patient monitors are used to monitor vital signs (pulse, breathing rate, blood pressure, body temperature, etc.) as well as ecg functions, and also to monitor blood oxygen, carbon dioxide levels. The integration of these functions into a single device would make the operating room simpler and more user-friendly. The afe for the patient watch is similar to the diagnostic ecg, but meets the rf inhibition requirement because during the operation, it is subject to high-intensity rf interference with electro- and americ ion condensation (apc) equipment. In addition, the ability to recover rapidly from heart defibrillation operations is an essential requirement for such afes. Work-use is also an important indicator because of the use of communication power and the availability of backup batteries in the patient watch. The shell must be waterproof and clean, which, of course, affects cooling corridors, and therefore the problem of dissipation must also be considered. In addition to working and spreading heat, the key to the design of the patient watch is rf inhibition and low noise indicators。
