Monitor is a device or system to measure and control the patient's physiological parameters, and can be compared with the known set values, if there is an exceedance of the standard can be issued an alarm.
Monitoring Parameters
Electrocardiogram
Electrocardiogram is one of the most basic monitoring items of the monitor, and the electrocardiogram signals are obtained through the electrodes, and the electrodes used for monitoring are disposable AS-AGCI button electrodes.
Heart rate
Heart rate is the number of heart beats per minute. Heart rate measurement is based on the electrocardiogram waveform and determines the instantaneous and average heart rates.
The average heart rate in a healthy adult is 75 beats/minute in a quiet state, with a normal range of 60-100 beats/minute. Under different physiologic conditions, the heart rate can be as low as 40-50 beats/min and as high as 200 beats/min.
Monitor heart rate alarm range: the low limit is 20-100 beats/min, and the high limit is 80-240 beats/min.
Respiration
Respiration refers to the respiratory rate of the monitoring patient, i.e. respiratory rate. The respiratory rate is the number of times the patient breathes in a unit of time, in minutes.
When breathing calmly, it is 60-70 breaths/minute for newborns and 12-18 breaths/minute for adults.
There are two types of measurements for respiratory monitoring: thermal and impedance
Thermal respiratory measurements are made with a thermistor placed at the nostrils. When airflow passes through the thermistor, it is subjected to heat exchange from the flowing airflow and the resistance value changes, thus the respiratory rate is measured.
Impedance type respiratory measurement is based on the human respiratory movement, the chest and arm muscles alternately flaccid, the thorax is also alternately deformed, the electrical impedance of the muscle tissue is also alternately changed, the respiratory impedance (pulmonary impedance) and the lung capacity of the existence of a certain relationship between the lung impedance with the increase in lung capacity and increase. Impedance respiratory measurement is designed according to the change of pulmonary impedance.
In monitoring measurements, the respiratory impedance electrode is used in conjunction with the cardiac electrode, i.e., the cardiac electrode detects both the cardiac signal and the respiratory impedance.
Invasive blood pressure
Invasive blood pressure is the monitoring of the patient's central venous pressure, left atrial pressure, cardiac output, and cardiac floatation catheter.
Central venous pressure is the large thoracic venous pressure or right atrial, which is more reflective of overall venous return than local venous pressure, which is 6.7-10.7 KPA in normal subjects and up to 22.7 KPA in patients with heart 3 failure .
Central venous pressure is measured by inserting an intravenous catheter from the jugular vein and femoral vein, and entering the junction of the superior and inferior vena cava and the right atrium through the large vein.
Left atrial pressure can indicate the ability of the left ventricle to fill and discharge, left heart failure, the left look forward to the ventricle's blood discharge is reduced, the left atrial pressure is elevated, can cause pulmonary stasis and emphysema,,, but the cardiac discharge is also increased. Therefore, monitoring and maintaining an appropriate left atrial pressure is extremely important for maintaining cardiac output.
Left atrial pressure is measured indirectly by inserting a cardiac catheter into the pulmonary artery and measuring pulmonary artery pressure, or by inserting a cardiac catheter directly into the left atrium through the left upper pulmonary vein-left atrial junction.
Noninvasive blood pressure
Noninvasive blood pressure monitoring uses the Koch sound detection method, using an inflatable cuff to block the brachial artery, a series of sounds with different pitches will appear during the drop in pressure at the end of the block, and the systolic and diastolic blood pressure can be determined according to the pitch and time, which are the Koch sounds.
When monitoring, a microphone is used as the sensor. When the cuff pressure is higher than the systolic pressure, the blood vessels are compressed, the blood under the cuff stops flowing, and there is no signal from the microphone. When the microphone measures the first kurtosis tone, the pressure corresponding to the cuff is systolic pressure. Then the microphone measures the kyphotic tone from the decrescendo phase to the silent phase, and the pressure corresponding to the cuff is the diastolic pressure.
Cardiac output
Cardiac output is an important measure of cardiac function, which is reduced in certain pathologic conditions, leaving the muscle with an inadequate supply of nutrients. Cardiac output is the amount of blood ejected from the heart per minute, and it is measured by injecting a certain amount of indicator into the bloodstream in a certain way, and after diffusion in the bloodstream, the change in the indicator is measured to calculate the cardiac output.
There are two methods of measuring cardiac output: the FICK method and the thermodilution method.
The FICK method uses oxygen as an indicator in the open circulation, and since the amount of oxygen exchanged between the pulmonary capillaries and alveoli is directly proportional to the pulmonary blood flow, cardiac output can be measured by measuring the oxygen concentration in the pulmonary arteries and pulmonary veins.
The thermodilution method uses cold saline as the indicator and a Swan-Ganz floating catheter with a thermistor as the cardiac catheter. The thermistor is placed in the pulmonary artery and cold saline is injected into the right atrium to calculate cardiac output.
Body Temperature
Body temperature reflects the results of the body's metabolism and is one of the conditions for normal functional activity. The temperature inside the body is called "body core temperature", reflecting the condition of the head or trunk, generally measured from the mouth, armpit, rectum, the Chinese statistics show that the oral temperature of 36.7-37.7 degrees, the axillary temperature of 36.9-37.4 degrees, rectal temperature of 36.9-37.9 degrees. -37.9 degrees.
Pulse
Pulse is the phenomenon of arterial blood vessels periodically pulsating with the heart's expansion and contraction, and it involves a variety of physical quantities such as changes in intravascular pressure, volume, displacement, and wall tension.
Optoelectronic volumetric pulse measurement is the most common of the monitoring measurements. The sensor consists of a light source and an optoelectronic transducer, which is clamped to the patient's fingertip or auricle. Light source selection of arterial blood oxygenated hemoglobin selectivity of a certain wavelength, preferably with light-emitting diodes, its spectrum in 6 * 10-7 * 10 M. This beam of light through the peripheral vasculature of the human body, when the dynamic
vein congestion changes in the volume, changing the transmittance of this beam of light, the optoelectronic converter to receive the light through the organization of the transmittance or reflection of the light, transformed into an electrical signal sent to the amplifier and output, thus reflecting the arterial pulse, and then the light is sent to the amplifier. The light is then converted into an electrical signal and sent to an amplifier for amplification and output, thus reflecting the change in arterial blood vessel volume.
The pulse is a signal that changes periodically with the heart's beat, and the volume of the arterial vessels also changes periodically, and the period of change of the signal from the photoelectric converter is the pulse rate.
Blood gases
Blood gas monitoring is primarily defined as partial pressure of oxygen (PO2), partial pressure of carbon dioxide (Pco2), and oxygen saturation (Spo2).
Oxygen and carbon dioxide exist in the blood in two states, physically dissolved and chemically bound, and it is the chemical binding that makes the blood's ability to transport O2 and Co2 so much greater.
Po2 is a measure of the amount of oxygen in arterial blood vessels, and Pco2 is a measure of the amount of carbon dioxide in venous blood vessels.
In O2 transportation, O2 mainly exists with hemoglobin in the form of binding in the red blood cells, the amount of dissolved is very small, so per 100 ml of blood, the maximum amount of hemoglobin-bound oxygen is called Oxygen Content (OCP), the amount of oxygen that hemoglobin is actually combined with the amount of oxygen is called Oxygen Content (OCN).
Blood oxygen saturation is the ratio of oxygen content to oxygen capacity.
Monitoring of oxygen saturation is also measured by photoelectric method, with the same sensor as for pulse measurement. Blood is bright red when Po2 is high and dark red when Po2 is low. The photoelectric converter has a low-pass characteristic. When light passes through blood with different Po2, the photoelectric converter accepts different frequencies of light, and due to the low-pass characteristic of the photoelectric converter, different frequencies of light pass through the photoelectric converter with different sensitivities. By measuring the sensitivity of the photoelectric converter, Po2 can be determined, and then Spo2 can be determined according to the oxygen separation curve.