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Choice ECG Monitor Observer MD100A Reference
Choice Observer ECG / EKG Monitor MD100A Documents
Observer MD100A Operational Manual in PDF format
Observer MD100A Quick Operation Guide in PDF format
Keep-It-Easy System User Manual: Software guide in PDF format
Understanding the MD100A Result
ECG Graph
The ECG graph follows the standard convention of 25 mm/s paper speed. Each small square represents 0.04 sec (40 msec) in time and 0.1 mV in voltage. Each large block represents 200 msec and one second interval takes up 5 large blocks. A heart rate of 60 bps would have 5 large blocks per cycle; a heart rate of 75 bps would have 4 large blocks per cycle.
Measurement Positions

ECG cable configurations for Lead I, II, and III
| LEAD | Cable | Body |
|---|---|---|
| I | RA | RA |
| LA | LA | |
| LL | LL | |
| II | RA | RA |
| LA | LL | |
| LL | LA | |
| III | RA | LA |
| LA | LL | |
| LL | RA |
Cable configuration: LA: positive, RA: negative, LL: neutral
Body position (see picture above):
- RA: Under clavicle, next to right shoulder
- LA: Under clavicle, next to left shoulder
- LL: At left of underbelly
An ECG machine is simply a highly sensitive voltmeter for measuring voltages between two points at your body. With proper placement of electrodes, one can obtain readings of the full 12 channels, albeit one channel at a time. See 12-lead ECG Monitor for more details.
ECG Arrhythmia Analysis
The following list of outputs was obtained from a recent email exchange with the manufacturer.
30-second measurement
- 84 - Stable waveform
- 3 - Suspected Sinus halted beat
- 4 - Suspected fast beat
- 6 - Suspected slow beat
- 7 - Suspected missing beat
- 9 - Suspected Repeating early beat
- 10 - Suspected trigeminy
- 11 - Suspected bigeminy
- 12 - Suspected R wave on T wave
- 14 - Suspected Twin early beat
- 15 - Suspected early beat
- 20 - Suspected the other arrhythmia
- 21 - Poor signal, try again
Continuous measurement
Note: Text in parenthesis is my interpretation of the code.
- V FIB (ventricular fibrillation)
- A FIB (artia fibrillation))
- ASYSTOLE (asystole)
- TACHY ( tachycardia)
- VTACHY (ventricular tachycardia)
- BRADY (bradycardia)
- MISSBEAT (missing beats)
- FREQPVC (frequent PVC)
- RUNPVC (run of PVC, PVC cluster)
- TRIGEMIN (PVCs that occur at intervals of 2 normal beats to 1 PVC)
- BIGEMINY (PVCs that occur after every normal beat)
- R On T (R waves interrupting T waves)
- INTERPVC (ventricular parasystole???)
- COUPLET (two PVCs in a row)
- PVC (premature ventricular contraction))
Tips from other users
Tight connectors. To ensure proper contact, it may take some "unreasonable amount of force" and wriggling to fully insert the connector into the socket. However, after a few insertions, the connector is "trained" so the insertion would be much easier.
Loose cable connection. Good connection is essential to obtain a good ECG graph. When you plug the ECG cable into MD100A, make sure the plug is in all the way as shown in the left diagram below. When looking from the bottom of a MD100A, the ridge on the plug is mostly hidden. The socket may be tight and require some maneuvering to push the plug in. The right diagram below is an example when the plug is not in properly.

Other measurement positions. Readings can also be taken from other positions. For example, placing one electrode on the right palm and another electrode on the left calf (inner) would generate a reading corresponding to LEAD II. You can experiment with different positions using the basic 12 leads configuration as starting points.
Connection or synchronization problem. See Connecting the device to PC for more information.
UserDA.txt. If you run into problem with this file, it may be corrupted. Find and delete the file. Replace it with an empty one.
12-lead ECG readings. See Using a single-channel EKG machine to simulate a 12-lead ECG monitor for more details.
For more information on electrocardiogram, visit our ECG / EKG Monitor Resource Center.
Email report. To email the report, save the report to a file. To save to a file, print the report to "Microsoft XPS Documenter Writer," not your regular printer. Use a PDF printer if you prefer a PDF file.
Sample Report

The box labeled "Analyze Result" on the upper right corner shows the result the arrhythmia analysis.
Technical Data (MD100A1)
ECG Measurement:
- Channel amount: 1 (difference input)
- Measuring electrodes: Four integrative metal electrode, or three ECG electrode pieces connected to the ECG cable mount with selected ECG cable (optional).
- Three Measuring parts: The signals measured can be I lead (between right and left hand) and approximate II lead or III lead (between the both hands and the chest).
- Signal bandwidth: 0.5Hz-75Hz
- Sampling rate: 200Hz
- Heart rate measuring range: 30bpm-240bpm
- Heart rate measuring accuracy: 30~100bpm: ±2bpm; 101~240bpm: ±4bpm
Note: The signals measured by the device positioned from the right hand and left hand is lead I on a standard surface ECG. The signals measured by the device positioned from the right hand and left chest best approximates a frontal plane lead such as lead II on a standard surface ECG.
Display Mode:
- Display screen type: 160 x 240 dot matrix single color LCD.
- Dimension of display area: 70mm x 45mm
- Backlight: LCD back light
Dimension and Weight:
- Dimension: 136mm x 84mm x 21mm(Length x Width x Height)
- Weight: 100g (Not including Two AAA batteries)
Operating Environment:
- Operation Temperature: 5°C~40°C
- Atmosphere Pressure Range: 86kPa-106kPa
- Operation Humidity: ≤93%
- Operation Voltage: DC 3V (+0.3V, -0.8V); 2 AAA batteries
Storage Environment
- Storage Temperature: -20°C~40°C
- Storage Humidity: ≤80%
Data Storage:
- Every record stores ECG data for 30 seconds.
- The device can store 200 items of ECG strips records at most.
Product Accessories:
- 2 AAA Batteries
- Pouch
- Warranty card
- ECG cable (optional)
- Data cable
- Data Management Software
- Instruction manual
- Quick Operation Guide
Classification: According to the type of protection against electric shock, it can be classified as internally power equipment. its application type is CF and it is the movable common facility with no defibrillator or protection.
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