1. The role and significance of the monitor
- The monitor is one of the most popular medical devices in clinical monitors and is necessary equipment for emergency departments, operating rooms, and ICUs.
- The monitor measurement the physiological parameters. And also monitors and processes the medication and the conditions before and after the operation.
- The
use of monitors provides a basis for doctors to diagnose and formulate medical
plans and reduce the mortality rate of critically ill patients.
2, The classification of medical monitoring equipment
- Classified by detection parameters: single-parameter monitors and multi-parameter monitors
- Classified by the scope of use: bedside monitors, central monitors, and discharged monitors
- Classified by instrument structure-function: integrated monitor and plug-in monitor
3, the principle of commonly used monitoring parameters
ECG
- The amplitude range of the ECG signal: 0.01-5mV.
- The frequency range of the ECG signal: 0.05-100Hz, 90% of the ECG frequency energy concentrates between 0.25Hz-40Hz.
- European standard R, L, F, N, C, corresponding colors: red, yellow, green, black, white.
- The American standard by RA, LA, LL, RL, and V. The corresponding colors are white, black, red, green, and brown. The five-lead method is to increase the driving electrode and the chest electrode based on the three-lead.
ECG measurement
The ECG electrodes are placed at two points separated by a certain distance on the body surface. These two points constitute a lead, and the connection between the two points represents the axis and has directionality.
ECG and ECG monitoring methods
- 12-lead ECG: Features: less interference from exercise than traditional ECG, requirement: accurate placement of each lead
- 3, 5-lead ECG monitoring
Clinical Significance of ECG Monitoring
- Heart rhythm monitoring:
- Heart rate monitoring:
- Causes
of increased heart rate: hypoxia, fever, early drop in blood pressure, blood
loss, pain, medication.
Causes of slow heart rate: extreme hypoxia, myocardial ischemia, cariostatic drug poisoning, critical illness, ventricular fibrillation, arrest, conduction block, hyperkalemia
Blood oxygen saturation
Oxygen is indispensable in life activities. The Oxygen combines with the hemoglobin in the blood and moves to all tissues in the body.
SpO2: Hemoglobin combined with oxygen in arterial blood accounts for the percentage of total hemoglobin. The range of SpO2 for healthy adults is 94% to 100%.
The measurement principle of blood oxygen saturation
We assume that only arterial blood has pulsatile characteristics to solve the light absorption effect of tissue and venous blood. The expansion of small arteries when pulsating increases the length of the light path. At the same time, it also increases the degree of light absorption.
Influencing factors of SpO2 measurement
- Hypoperfusion: shock, hypothermia, drug influence
- Motion interference (Masimo algorithm)
- Nails: anemia, stains, light interference
More about Spo2 reading -- What Influence Spo2 reading
Non-invasive blood pressure
The non-invasive blood pressure measurement adopts the oscillation method. Then deflate the cuff gradually in the form of linear (3-5mmHg) or step deflation (6-15mmHg), and process the pulsation signal in the air circuit with the pressure sensor and corresponding amplification, filter circuit, A/D, etc. to convert the original signal to digital wave display.
Factors affecting the accuracy of blood pressure measurement
- The cuff is too big or too small.
- The cuff is placed incorrectly.
- Patients with arrhythmia.
- The patient's movement during measurement.
- The patient is in severe shock, hypothermia, etc.
- Patients connected to artificial heart-lung machine.
- The patient's blood pressure changes drastically during the measurement.
Invasive blood pressure
Principle of pressure measurement
It uses the principle of equal pressure transmission of liquid to achieve direct blood pressure measurement.
Method
Using an arterial cannula to guide the blood pressure and its changes in the arteries to the pressure sensing surface of the pressure-sensitive sensor through a pipeline containing saline, and then the pressure-sensitive sensor linearly converts the pressure signal in the artery into an electrical signal
Precautions
- Reset the machine before starting monitoring, and at least once a day (zero-reset after each cable is unplugged)
- Place the sensor at the same level as the heart
- Disposable sensors or caps cannot be re-sterilized or reused.
0 Comments