The monitor is a device or system that can measure and control the physiological parameters of patients, and can be compared with the known set values, and if it exceeds the standard, it can give an alarm.
Monitoring parameters
electrocardiogram
Electrocardiogram is one of the most basic monitoring items of monitoring instruments. Electrocardiogram signals are obtained through electrodes, which are disposable AGCI button electrodes.
heart rate
Heart rate refers to the number of heartbeats per minute. Heart rate measurement is to measure instantaneous heart rate and average heart rate according to ECG waveform.
The average heart rate of healthy adults in quiet state is 75 beats/min, and the normal range is 60- 100 beats/min. Under different physiological conditions, the heart rate can be as low as 40-50 beats/min and as high as 200 beats/min.
Heart rate alarm range of the monitor: the lower limit is 20- 100 beats/min, and the upper limit is 80-240 beats/min.
breathe
Breathing refers to monitoring the patient's breathing frequency, that is, breathing frequency. Breathing frequency is the number of breaths in a unit time, and the unit is minutes.
When breathing calmly, the neonatal rate is 60-70 beats/min, and the adult rate is 12- 18 beats/min.
There are two measurement methods for respiratory monitoring: thermal measurement and impedance measurement.
Thermal respiration measurement is to put a thermistor at the nostril. When the airflow passes through the thermistor, the thermistor is subjected to heat exchange by the flowing airflow, and the resistance value changes, thus measuring the respiratory frequency.
Impedance respiration measurement is based on the fact that the muscles of the chest and arms are alternately relaxed, the chest is also alternately deformed, and the electrical impedance of the body tissue is alternately changed. Respiratory impedance (pulmonary impedance) has a certain relationship with vital capacity, and pulmonary impedance increases with the increase of vital capacity. Impedance respiration measurement is designed according to the change of pulmonary impedance.
In monitoring measurement, respiratory impedance electrode is used together with ECG electrode, that is, ECG electrode detects ECG signal and respiratory impedance at the same time.
Invasive blood pressure
Invasive blood pressure refers to monitoring patients' central venous pressure, left atrial pressure, cardiac output and cardiac floating catheter.
Central venous pressure refers to the great thoracic venous pressure or the right atrium, which can better reflect the overall venous return than local venous pressure. The pressure of normal people is 6.7- 10.7 kPa, and that of patients with heart failure can reach 22.7KPA.
Venous catheters were inserted from jugular vein and femoral vein, and entered the junction of superior and inferior vena cava and right atrium through great vein, and the central venous pressure was measured.
Left atrial pressure can indicate the filling and discharging ability of left ventricle. Left heart failure, looking around and increasing left atrial pressure can cause pulmonary congestion and emphysema, but the cardiac output also increases. Therefore, monitoring and maintaining proper left atrial pressure is extremely important for maintaining cardiac output.
The left atrial pressure is measured indirectly by inserting a cardiac catheter into the pulmonary artery to measure the pulmonary artery pressure, or by inserting a cardiac catheter directly into the left atrium through the junction of the left upper pulmonary vein and the left atrium.
Non-invasive blood pressure
Non-invasive blood pressure monitoring adopts Coriolis sound detection method, and brachial artery is blocked with inflatable cuff. A series of sounds with different tones will appear during the pressure drop at the blocking end. Systolic blood pressure and diastolic blood pressure can be judged according to pitch and time, which is Coriolis sound.
When listening, the microphone acts as a sensor. When the cuff pressure is higher than the systolic pressure, the blood vessels are squeezed, the blood under the cuff stops flowing, and there is no signal from the microphone. When the microphone detects the first Kirchhoff sound, the corresponding pressure of the cuff is systolic pressure. Then the microphone measures Kirchhoff sound from silent stage to silent stage, and the corresponding pressure of the cuff is diastolic pressure.
cardiac output
Cardiac output is an important index to measure cardiac function. In some pathological conditions, the cardiac output is reduced, which makes the body's nutritional supply insufficient. Cardiac output is the amount of blood injected into the heart every minute. It is to inject a certain amount of indicator into blood in a certain way, and then measure the change of indicator after diffusion in blood to calculate cardiac output.
There are two methods to measure cardiac output: Fick method and thermal dilution method.
Fick's method takes oxygen in open blood circulation as an index. Because the oxygen exchange between pulmonary capillaries and alveoli is proportional to pulmonary blood flow, cardiac output can be measured by measuring the oxygen concentration of pulmonary artery and pulmonary vein.
Thermal dilution method takes cold physiological saline as indicator and Swan-Ganz floating catheter with thermistor as heart catheter. Thermistor was placed in pulmonary artery, and cold saline was injected into right atrium to calculate cardiac output.
temperature
Body temperature reflects the result of body metabolism and is one of the conditions for normal functional activities. The temperature inside the body is called the "body core temperature", which reflects the condition of the head or trunk. Generally measured from the mouth, armpit and rectum. According to the statistics of China people, the temperature of the mouth is 36.7-37.7 degrees, the temperature of the armpit is 36.9-37.4 degrees, and the temperature of the rectum is 36.9-37.9 degrees.
pulse
Pulse is a phenomenon that arterial blood vessels pulsate periodically with the contraction and contraction of the heart. Pulse includes changes of various physical quantities such as intravascular pressure, volume, displacement and wall tension.
Photoelectric volume pulse measurement is the most common in monitoring measurement. The sensor consists of a light source and a photoelectric transducer, which is clamped on the fingertip or auricle of the patient. The light source is selected with a certain wavelength selective to oxygenated hemoglobin in arterial blood, and it is best to use light-emitting diodes, and its spectrum is 6 *10-7 *10m. This beam of light passes through the peripheral blood vessels of the human body and moves when it moves.
When the congestion volume of the pulse changes, the transmittance of this beam of light changes, and the light transmitted or reflected by the tissue is received by the photoelectric converter, converted into electrical signals and sent to the amplifier for amplification and output, thus reflecting the volume change of arterial blood vessels.
Pulse is a signal that changes periodically with heartbeat, and arterial volume also changes periodically. The signal change period of photoelectric converter is pulse rate.
vitality
Blood gas monitoring mainly refers to partial pressure of oxygen (PO2), partial pressure of carbon dioxide (Pco2) and oxygen saturation (Spo2).
Oxygen and carbon dioxide exist in blood in two States: physical dissolution and chemical combination. It is precisely because of the existence of chemical combination that the ability of blood to transport O2 and Co2 is greatly improved.
Po2 is a measure of oxygen content in arterial blood vessels. Pco2 is a measure of carbon dioxide content in venous blood vessels.
In the transport of O2, O2 mainly exists in red blood cells in the form of combining with hemoglobin, and the dissolved amount is extremely small. Therefore, the maximum oxygen content bound by hemoglobin per 100 ml of blood is called oxygen content (OCP), and the actual oxygen content bound by hemoglobin is called oxygen content (OCN).
Oxygen saturation is the ratio of oxygen content to oxygen capacity.
The monitoring of oxygen saturation is also measured by photoelectric method, and the sensor is the same as the pulse detector. When Po2 in blood is high, the blood is bright red, and when Po2 is low, the blood is dark red. The photoelectric converter has a low-pass characteristic. When light passes through blood with different Po2, the photoelectric converter receives light with different frequencies. Because of the low-pass characteristic of photoelectric converter, light with different frequencies has different sensitivity when passing through photoelectric converter. By measuring the sensitivity of photoelectric converter, Po2 can be determined, and then Spo2 can be determined according to the oxygen dissociation curve.