Trouble shooting of ECG monitor

The monitor plays an important role in the whole monitoring process. Since the monitor works continuously for almost 24 hours, its failure rate is also high. Common failures and troubleshooting methods are introduced as follows:

1. No display at boot

Trouble phenomenon:

When the instrument is turned on, there is no display on the screen and the indicator light does not light; when an external power supply is connected, the battery voltage is low, and then the machine automatically shuts down; when the battery is not connected, the battery voltage is low, and then automatically shuts down, even if the machine is charged, it is useless.

Inspection Method:

? When the instrument is not connected to AC power, check whether the 12V voltage is low. This fault alarm indicates that the output voltage detection part of the power supply board has detected a low voltage, which may be caused by a failure of the detection part of the power supply board or a failure of the output of the power supply board, or it may be caused by a failure of the back-end load circuit.

?When the battery is installed, this phenomenon indicates that the monitor is working on battery power supply and the battery power is basically exhausted, and the AC input is not working normally. The possible reason is: the 220V power socket itself has no electricity, or the fuse is blown.

? When the battery is not connected, it is judged that the rechargeable battery is broken, or the battery cannot be charged due to the failure of the power board/charge control board.

Method of exclusion:

Connect all connection parts reliably, connect AC power to charge the instrument.

2. White screen, flower screen

Trouble phenomenon:

There is a display after booting up, but a white screen and a blurred screen appear.

Inspection Method:

A white screen and a flickering screen indicate that the display screen is powered by an inverter, but there is no display signal input from the main control board. An external monitor can be connected to the VGA output port on the back of the machine. If the output is normal, the screen may be broken or the connection between the screen and the main control board may be bad; if there is no VGA output, the main control board may be faulty.

Method of exclusion:

Replace the monitor, or check whether the main control board wiring is secure. When there is no VGA output, the main control board needs to be replaced.

3. ECG without waveform

Trouble phenomenon:

If the lead wire is connected and there is no ECG waveform, the display shows “electrode off” or “no signal receiving”.

Inspection Method:

First check the lead mode. If it is a five-lead mode but only uses a three-lead connection, there must be no waveform.

Secondly, on the premise of confirming the position of the heart electrode pads and the quality of the heart electrode pads, interchange the ECG cable with other machines to confirm whether the ECG cable is faulty, whether the cable is aging, or the pin is broken. .

Third, if the ECG cable failure is eliminated, the possible cause is that the “ECG signal line” on the parameter socket board is not in good contact, or the ECG board, the ECG main control board connection line, or the main control board is faulty.

Method of exclusion:

(1) Check all the external parts of the ECG lead (the three/five extension cords in contact with the human body should be connected to the corresponding three/five contact pins on the ECG plug. If the resistance is infinite, it indicates that the lead wire is open. , The lead wire should be replaced).

(2) If the ECG display waveform channel displays “No signal receiving”, it means there is a problem with the communication between the ECG measurement module and the host, and this prompt still persists after turning off and on, and you need to contact the supplier.

4. Unorganized ECG waveform

Trouble phenomenon:

The ECG waveform has large interference, and the waveform is not standard or standard.

Inspection Method:

(1) First of all, the interference from the signal input terminal should be eliminated, such as patient movement, heart electrode failure, aging of the ECG lead, and poor contact.

(2) Set the filter mode to “Monitoring” or “Surgery”, the effect will be better, because the filter bandwidth is wider in these two modes.

(3) If the waveform effect under the operation is not good, please check the zero-ground voltage, which is generally required to be within 5V. A ground wire can be pulled separately to achieve a good grounding purpose.

(4) If the grounding is not possible, it may be the interference from the machine, such as the poorly done ECG shielding. At this time, you should try to replace the accessories.

Method of exclusion:

Adjust the ECG amplitude to an appropriate value, and the entire waveform can be observed.

5. ECG baseline drift

Trouble phenomenon:

The baseline of the ECG scan cannot be stabilized on the display screen, sometimes drifting out of the display area.

Inspection Method:

(1) Whether the environment in which the instrument is used is humid, and whether the inside of the instrument is damp;

(2) Check the quality of the electrode pads and whether the parts where the human body touches the electrode pads are cleaned.

Method of exclusion:

(1) Turn on the instrument continuously for 24 hours to discharge moisture by itself.

(2) Replace good electrode pads and clean the parts where the human body touches the electrode pads.

6. Respiration signal is too weak

Trouble phenomenon:

The respiratory waveform displayed on the screen is too weak to observe.

Inspection Method:

Check whether the ECG electrode pads are placed correctly, the quality of the electrode pads, and whether the body contacting the electrode pads is cleaned.

Method of exclusion:

Clean the parts of the human body that touch the electrode pads, and place the electrode pads of good quality correctly.

7. ECG is disturbed by electrosurgical knife

Trouble phenomenon: The electrosurgery is used in the operation, and the electrocardiogram interferes when the negative plate of the electrosurgery contacts the human body.

Inspection method: Whether the monitor itself and the electric knife shell are well grounded.

Remedy: Install a good grounding for the monitor and electric knife.

8. SPO2 has no value

Trouble phenomenon:

During the monitoring process, there is no blood oxygen waveform and no blood oxygen value.

Inspection Method:

(1) Change a blood oxygen probe. If it doesn’t work, the blood oxygen probe or the blood oxygen extension cord may be faulty.

(2) Check if the model is correct. Mindray’s blood oxygen probes are mostly MINDRAY and Masimo, which are not compatible with each other.

(3) Check whether the blood oxygen probe is flashing in red. If there is no flashing, the probe component is faulty.

(4) If there is a false alarm for blood oxygen initialization, it is a failure of the blood oxygen board.

Method of exclusion:

If there is no flashing red light in the finger probe, it may be that the wire interface is in poor contact. Check the extension cord and the socket interface. In areas with cold temperatures, try not to expose the patient’s arm to avoid affecting the detection effect. It is not possible to perform blood pressure measurement and blood oxygen measurement on the same arm, so as not to affect the measurement due to compression of the arm.

If the blood oxygen display waveform channel displays “No signal receiving”, it means that there is a problem with the communication between the blood oxygen module and the host. Please turn off and then turn on again. If this prompt still exists, you need to replace the blood oxygen board.

9. SPO2 value is low and inaccurate

Trouble phenomenon:

When measuring human blood oxygen saturation, the blood oxygen value is sometimes low and inaccurate.

Inspection Method:

(1) The first thing to ask is whether it is for a particular case or general. If it is a special case, it can be avoided as much as possible from the precautions of blood oxygen measurement, such as patient exercise, poor microcirculation, hypothermia, and long time.

(2) If it is common, please replace a blood oxygen probe, it may be caused by the failure of the blood oxygen probe.

(3) Check whether the blood oxygen extension cord is damaged.

Method of exclusion:

Try to keep the patient stable. Once the blood oxygen level is lost due to hand movements, it can be considered normal. If the blood oxygen extension cord is broken, replace one.

10. NIBP under-inflated

Trouble phenomenon:

The blood pressure measurement time reports “cuff too loose” or the cuff is leaking, and the inflation pressure cannot be filled (below 150mmHg) and cannot be measured.

Inspection Method:

(1) There may be a real leak, such as cuffs, air ducts, and various joints, which can be judged by “leak detection”.

(2) The patient mode is incorrectly selected. If an adult cuff is used but the monitoring patient type uses a neonate, this alarm may occur.

Method of exclusion:

Replace the blood pressure cuff with good quality or choose a suitable type.

11. NIBP measurement is not accurate

Trouble phenomenon:

The deviation of the measured blood pressure value is too large.

Inspection Method:

Check whether the blood pressure cuff is leaking, whether the pipe interface connected with blood pressure is leaking, or whether it is caused by the difference of subjective judgment with the auscultation method?

Method of exclusion:

Use NIBP calibration function. This is the only standard available to verify the correctness of the NIBP module calibration value at the user’s site. The standard deviation of pressure tested by NIBP at the factory is within 8mmHg. If it exceeds, the blood pressure module needs to be replaced.

12. Module communication is abnormal

Trouble phenomenon:

Each module reports “communication stop”, “communication error”, and “initialization error”.

Inspection Method:

This phenomenon indicates that the communication between the parameter module and the main control board is abnormal. First, plug and unplug the connection line between the parameter module and the main control board. If it does not work, consider the parameter module, and then consider the failure of the main control board.

Method of exclusion:

Check whether the connection line between the parameter module and the main control board is stable, whether the parameter module is set correctly, or replace the main control board.