Patient Monitor As One Of The Most Commonly Used Medical Devices

- Jun 21, 2018-

As one of the most commonly used medical devices, the Patient monitor is widely used in various clinical departments and has a high frequency of use. Therefore, the number of failures is relatively large. To ensure the normal operation of the Patient monitor, not only can the patient provide comprehensive Patient monitoring, but also improve the efficiency of the medical staff, and provide important and effective information for disease analysis and diagnosis.

The following describes how to troubleshoot and troubleshoot common Patient monitoring problems with the Patient monitor.

First, ECG-related failures

The Patient monitoring of the ECG of the Patient monitor is the process of detecting the potential difference formed by the bioelectric current generated on the body surface by using the ECG lead to detect and receive the electrical excitation of the heart. There are two common types of Patient monitor failures:

Symptom: After the human body is correctly connected to the ECG electrode, the Patient monitor prompts "no signal reception" or "electrode dropout."

Fault analysis and exclusion: The Patient monitor prompts "no signal reception" or "electrode dropout", which is usually caused by the electrode falling off, damage, or malfunction of the ECG module. The ECG analog signal generator can be used for detection.

Exclusion procedure: Correctly connect ECG analog signal generator and ECG lead wire, and start detection.

(1) If the waveform and numerical value of the ECG signal are normal, the Patient monitor and the ECG lead are normal. Check whether the electrode and the human body are connected properly. If the electrode is peeled off or the pad is used for too long, it will result in no display of the ECG waveform.

(2) If there is no waveform or numerical display of the ECG signal, it is necessary to judge whether the ECG lead wire is intact. Replaceable ECG leads are tested again. If the fault is removed, the original ECG leads are damaged and need to be replaced.

(3) If the fault has not been removed after replacing the ECG lead wire, you should suspect that the ECG module is faulty and you need to disassemble it for maintenance or replacement.

Symptoms: ECG signal scan baseline can not be displayed on the screen, drift indefinite; abnormal ECG waveform or interference, measured value is not allowed.

Failure analysis and exclusion: ECG baseline drift, abnormal waveforms, inaccurate measurements, generally associated with external interference or machine settings.

Exclusion steps:

(1) Check whether the patient's electrode pads are clean and moist. If necessary, use alcohol to clean the skin.

(2) Check whether the electrode pads are connected properly or melted because they are used for too long. They need to be replaced. It is generally recommended that the pads should be replaced within about 3 hours.

(3) The inside of the machine is damp, and it needs to be continuously turned on for 24 hours for drying.

(4) Move the machine to a place with less electromagnetic interference and restart the observation to eliminate the influence of electromagnetic interference from peripheral machines.

(5) Check whether the machine AC power supply has a grounding wire. If it is not connected, it must be reconnected.

(6) Check whether the selected ECG filtering method or power frequency setting is correct. If it is not correct, select the appropriate filtering method and power frequency (usually set to 50Hz).

Second, SPO2 related faults

The Patient monitor measures SPO2 using the absorbance characteristics of Hb and HbO2-εcd in the blood and the lambdaier's law I=I0e (where I and I0 are incident and transmitted light intensities, respectively, ε, c, d are Material absorption coefficient, solution concentration, and light passage path are achieved. There are two kinds of common faults:

Symptoms: In the normal power-on condition, there is no blood oxygen waveform and digital display. Failure analysis and exclusion: no blood oxygen waveform and digital display, generally due to the blood oxygen probe damage or blood oxygen module failure.

Exclusion procedure: connect the oxygen probe properly and start the test.

(1) Determine if the blood oxygen probe is intact. You can check if the diode light in the probe is normal or replace it with a new one. If it is determined that the probe is damaged, it needs to be replaced. There are generally two types of damage to the PO2 probe:

1 finger sets in the light-emitting diode or photodiode burned;

2 The inner conductor of the connector is desoldered. At this time, the connector can be unscrewed and the circuit re-welded.

(2) Check that the machine probe connection port and its wiring are normal. Dropping or loosening of the probe's ports or connected lines, connectors, can cause the probe to fail. At this point, you need to disassemble the port and the line to re-fix the probe detection.

(3) If the possible failures mentioned in the previous two steps have been eliminated and the machine still does not have a blood oxygen waveform and a digital display, the oxygen module should be considered for failure and need to be repaired or replaced.

Symptoms: Blood oxygen waveforms and figures are displayed, but the waveform interference is large or the blood oxygen measurement is inaccurate.

Failure analysis and exclusion: blood oxygen waveform interference or measurement values are not accurate, generally caused by external environmental factors.

Exclusion procedure: Exclude the interference of the patient's own activity, make the patient quiet and test. Care should be taken to detect the effects of light in the environment. From the light absorption characteristics of HbO2 and Hb shown in Fig. 1 and Lambertian's law (I=I0e), it can be seen that when strong light (especially red light and infrared light) is irradiated in the detection environment, I0 and I may be changed. , resulting in inaccurate measurements.

Also pay attention to the effect of the dye. If a patient is injected with a stain before performing SPO2 measurements, the blood concentration (c) and the absorbance coefficient (ε) will change, affecting the final measurement.

Finally, avoid measuring with the NIBP on the same side or using the same finger for a long time. When the SPO2 probe cuff is pressed against the same finger for a long time, and the compression force of the cuff on the arm is measured by the NIBP measurement, blood flow of the finger may be poor, which may cause measurement errors and patient discomfort.