Faulty Analysis Method of A Patient Monitor | NIBP Fault Analysis and Troubleshooting
The monitor measures NIBP using the vibration wave method. During the measurement process, the pulsation of the blood vessel wall caused by the blood flow will generate a gas vibration wave in the cuff, and the vibration wave will be transmitted to the pressure sensor in the machine through the trachea to detect the cuff pressure in real-time. There are two common faults:
Fault 1: When performing NIBP measurement, it prompts "cuff error", "air pump leak" or pressure error alarm. It is generally caused by airway leakage, blockage, or failure of the blood pressure module pump and air release valve.
(1) Check that the extension tube and cuff are not obviously damaged or folded and blocked, and need to be replaced if necessary.
(2) Check whether the extension tube is tightly connected with the cuff and the port of the machine. If necessary, clean the port with alcohol.
(3) The air pipe in the machine falls off or becomes loose, causing air leakage. At this time, the machine needs to be disassembled to reconnect and reinforce the internal pipe.
(4) Troubleshoot the air pump and air release valve on the NIBP module.
①Air pump detection: Remove the air pump and connect it to the 12V DC power supply to test whether the air pump works and the air output is normal. If it is not normal, the air pump is damaged and needs to be replaced;
②Bleed valve detection: Dust accumulation in the valve will cause the valve to be closed loosely or the airway in the valve to be blocked, which will cause the monitor to indicate air leakage fault or pressure error alarm respectively. At this time, the air valve can be removed, and the inside of the valve can be cleaned with a syringe. Replace the bleed valve or the NIBP module if necessary.
Fault 2: The external air circuit is intact, and it can be filled and deflated normally, but there is no blood pressure value or the blood pressure value is inaccurate.
(1)Choose an appropriate size cuff, remove the body surface barrier and squeeze out the gas in the cuff before binding the cuff. If the cuff is too loose or too tight, the gas in the cuff will not be able to feel the pulsation of the blood vessel wall normally and generate vibration waves, resulting in inaccurate blood pressure measurement or inaccurate measurement.
(2) The influence of the patient's own activities is excluded. One of the main disadvantages of using the vibration wave method to measure NIBP is that it is easily disturbed by external vibration. Therefore, the NIBP measurement should be carried out in a calm state.
(3) The cuff binding position and patient posture should be correct. The results of the study show that for every 10cm difference between the position measured by NIBP and the height of the heart, the measured blood pressure value will differ by about 8mmHg. Therefore, when measuring NIBP, the measurement position should be kept at the same height as the heart.
(4) The failure of the blood pressure module should be considered. Damage to the pressure sensor or signal processing system in this module will result in no measurement results or inaccurate measurement values. In this case, the module needs to be disassembled for maintenance or replacement.