What Is a Medical Monitor?

A monitor is a device or system that measures and controls a patient's physiological parameters and can be compared with known set values, and an alarm can be issued if there is an excess.

Chinese name: Monitor
Function: A method to measure and control patient physiological parameters

Instrument classification: Portable monitor, plug-in monitor
maintenance: Remove dirt with absolute alcohol

Monitor Instrument Introduction

Monitor meaning

A medical monitor is a device or system that measures and controls a patient's physiological parameters and can compare it with known set values. If there is an excess, an alarm can be issued. The monitor must continuously monitor the patient's physiological parameters for 24 hours, detect changes in trends, point out critical situations, and provide the basis for emergency treatment and treatment by doctors to minimize complications and achieve the purpose of relieving and eliminating the disease. In addition to measuring and monitoring physiological parameters, the use of the monitor also includes monitoring and processing of medication and conditions before and after surgery.

With the steady growth of the medical device market in our country, medical monitors have also been used mainly for the care of critically ill patients in the past, and have developed into the current monitoring of ordinary wards. Even basic-level medical units and community medical units have also raised application requirements.

In 2009, the penetration rate of medical monitors in China was only 20%. The penetration rate of medical monitors is positively related to the living standards of a country. In 2009, China's per capita GDP was 3678 US dollars. Judging from the compound growth rate of China's per capita GDP in the past 20 years, the compound annual growth rate of the penetration rate of medical monitors in China in the next 5 years is about 8.01%. From the perspective of the long-term development of the industry, with the further improvement of the industry's research and development level and the further improvement of China's medical security system, high-end products will gradually become the mainstream.

The monitor is different from the monitoring and diagnostic equipment. It must continuously monitor the patient's physiological parameters for 24 hours, detect changes in trends, point out critical situations, and provide a basis for emergency treatment and treatment by doctors to minimize complications, achieve relief and eliminate the disease the goal of.

In addition to measuring and monitoring physiological parameters, the use of the monitor also includes monitoring and processing of medication and conditions before and after surgery.

The standard 6 parameters of the monitor are ECG, breathing, non-invasive blood pressure, blood oxygen saturation, pulse, and temperature. In addition, optional parameters include: invasive blood pressure, end-respiratory carbon dioxide, respiratory mechanics, anesthetic gas, cardiac output (invasive and non-invasive), dual-frequency EEG index, and so on.

Clinical application of the monitor: during surgery, after surgery, trauma care, coronary heart disease, critically ill patients, newborns, premature infants, hyperbaric oxygen chambers, delivery rooms, etc.

Monitor instrument classification

According to the structure, it is divided into four categories: portable monitors, plug-in monitors, telemetry monitors, and HOLTER (24-hour dynamic electrocardiogram) ECG monitors.

They are divided into three categories according to their functions: bedside monitors, central monitors, and out-of-hospital monitors (telemetry monitors).

Bedside monitor is an instrument that is connected to the patient at the bedside. It can continuously monitor various physiological parameters or certain states of the patient, display alarms or records, and it can also form a central monitor. Work as a whole.

The central monitor is also called the central system monitor. It is composed of a main monitor and a number of bedside monitors. The main monitor can control the work of each bedside monitor and monitor the situation of multiple monitored objects simultaneously An important task is to complete the automatic recording of various abnormal physiological parameters and medical records.

The out-of-hospital monitor (telemetry monitor) enables patients to carry a small electronic monitor that can continuously monitor certain physiological parameters of patients inside and outside the hospital for non-real-time inspection by doctors.

Monitor monitoring parameters

Monitor ECG

ECG is one of the most basic monitoring items of monitoring equipment. ECG signals are obtained through electrodes. Monitoring electrodes are disposable AS-AGCI button electrodes.

Monitor heart rate

Heart rate is the number of times your heart beats per minute. Heart rate measurement is based on the ECG waveform to determine the instantaneous heart rate and average heart rate.

Healthy adults have an average heart rate of 75 beats / min in a quiet state, 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 the highest can be 200 beats / min.

Monitor heart rate alarm range: low limit of 20-100 times / min, high limit of 80-240 times / min.

Monitor breath

Respiration refers to the breathing rate of the monitored patient, which is the breathing rate. Respiratory frequency is the number of times a patient breathes in a unit of time, and the unit is minutes.

When breathing quietly, the newborn is 60-70 beats / min and the adult is 12-18 beats / min.

There are two measurement methods for respiratory monitoring: thermal and impedance

Thermistor breathing measurement uses a thermistor placed on the nostril. When the airflow passes through the thermistor, the thermistor is heat-exchanged by the flowing airflow, the resistance value changes, and the frequency of the breath is measured.

Impedance respiration measurement is based on the human body's breathing movement, the chest and arm muscles alternately relax, the thorax also deforms alternately, and the electrical impedance of the body tissue changes alternately. There is a certain relationship between respiratory impedance (lung impedance) and lung capacity. Lung impedance varies with the lungs. The capacity increases. Impedance breathing measurement is designed based on changes in lung impedance.

In monitoring measurement, the respiratory impedance electrode is used in combination with the ECG electrode, that is, the ECG electrode and the respiratory impedance are detected simultaneously.

Monitors have invasive blood pressure

Invasive blood pressure refers to the central venous pressure, left atrial pressure, cardiac output, and cardiac floating catheter of a monitored patient.

Central venous pressure refers to the large thoracic venous pressure or right atrium. It reflects the entire venous return situation more than local venous pressure. It is 6.7-10.7 KPA in normal people and 22.7 KPA in patients with heart failure.

The central venous pressure is measured by inserting it from the jugular vein and femoral vein with a venous catheter, and entering the superior and inferior vena cava through the large vein to the junction of the right atrium to measure the central venous pressure.

Left atrial pressure can indicate the capacity of the left ventricle to fill and drain. Left heart failure, left and right ventricle blood volume reduction, left atrial pressure increase, can cause pulmonary congestion and emphysema, but 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 by inserting a cardiac catheter into the pulmonary artery and measuring the pulmonary artery pressure to indirectly measure the left atrial pressure, or by inserting the cardiac catheter directly into the left atrium through the left upper pulmonary vein and the left atrium.

Non-invasive blood pressure monitor

Non-invasive blood pressure monitoring uses Coriolis sound detection method, using an inflatable cuff to block the brachial artery, a series of different tones will appear during the pressure drop of the obstruction. According to the tone and time, systolic and diastolic blood pressure can be judged. Coriolis.

When monitoring, a microphone is used as a sensor. When the cuff pressure is higher than the systolic pressure, the blood vessels are squashed, the blood under the cuff stops flowing, and the microphone has no signal. When the microphone detects the first coriolis, the pressure corresponding to the cuff is the systolic pressure. The microphone then measured the chorus from the attenuation phase to the silent phase, and the corresponding pressure on the cuff was diastolic pressure.

Monitor cardiac output

Cardiac output is an important indicator of cardiac function. Under certain pathological conditions, cardiac output decreases, resulting in insufficient nutritional supply of the body. Cardiac output is the amount of blood ejected by the heart per minute. It is measured by injecting a certain amount of indicator into the blood in a certain way, and measuring the change in indicator to diffuse the blood to calculate the cardiac output.

There are two methods for measuring cardiac output: FICK method and thermal dilution method.

The FICK method uses oxygen as an indicator in open blood circulation. Since the amount of oxygen exchange between the pulmonary capillary and the alveoli is proportional to the pulmonary blood flow, the cardiac output can be measured by measuring the oxygen concentration of the pulmonary arteries and pulmonary veins.

The thermal dilution method uses cold physiological saline as an indicator and a Swan-Ganz floating catheter with a thermistor as a cardiac catheter. The thermistor was placed in the pulmonary artery and cold saline was injected into the right atrium to calculate the cardiac output.

Monitor temperature

Body temperature reflects the result of the body's metabolism and is one of the conditions for the body to perform normal functional activities. The temperature inside the body is called "core temperature", which reflects the condition of the head or trunk. It is generally measured from the mouth, axilla, and rectum. According to statistics from the Chinese, the oral temperature is 36.7-37.7 degrees, the underarm temperature is 36.9-37.4 degrees, and the rectal temperature 36.9-37.9 degrees.

Monitor pulse

Pulse is a phenomenon in which arterial blood vessels periodically pulsate with the contraction of the heart. Pulses include changes in various physical quantities such as intravascular pressure, volume, displacement, and wall tension.

Photovoltaic volume pulse measurement is the most common in monitoring measurement. The sensor consists of a light source and a photoelectric converter. It is clamped on the patient's fingertips or auricle. The light source selects a certain wavelength that is selective for oxyhemoglobin in arterial blood. It is best to use light-emitting diodes, whose spectrum is 6 * 10-7 * 10M. This beam of light passes through the human peripheral blood vessels and moves

When the pulse congestion volume changes, the light transmittance of this beam is changed. The photoelectric converter receives the light transmitted or reflected by the tissue, and converts it into an electrical signal for amplifier amplification and output, thereby reflecting the volume change of the arterial blood vessel.

The pulse is a signal that changes periodically with the pulsation of the heart, and the arterial blood vessel volume also changes periodically. The signal change period of the photoelectric converter is the pulse rate.

Monitor blood gas

Blood gas monitoring mainly refers to partial oxygen pressure (PO2), partial pressure of carbon dioxide (Pco2), and blood oxygen saturation (Spo2).

Oxygen and carbon dioxide exist in the blood in two states: physical dissolution and chemical bonding. It is because of the chemical bonding that the blood's ability to transport O2 and Co2 is greatly improved.

Po2 is a measure of the oxygen content in arterial blood vessels. Pco2 is a measure of the amount of carbon dioxide in a vein.

In O2 transportation, O2 mainly exists in red blood cells in a combined form with hemoglobin, and the amount of dissolution is extremely small. Therefore, the maximum amount of hemoglobin-bound oxygen per 100ml of blood is called oxygen content (OCP). The quantity is called the Oxygen Content (OCN).

Blood oxygen saturation is the ratio of oxygen content to oxygen capacity.

The monitoring of blood oxygen saturation is also measured by the photoelectric method, the sensor and the pulse are the same. When Po2 is high in the blood, 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 the blood of different Po2, the photoelectric converter accepts light of different frequencies. Due to the low-pass characteristic of the photoelectric converter, light of different frequencies has different sensitivities through the photoelectric converter. By measuring the sensitivity of the photoelectric converter, Po2 can be measured, and then Spo2 can be measured according to the oxygen ionization curve.

Monitor maintenance

Monitor Overview

"The monitor can simultaneously and continuously monitor the patient's ECG, blood pressure, breathing, temperature and other parameters, providing a good way for medical staff to comprehensively, intuitively and timely grasp the patient's condition. As the hospital gradually moves towards modernization, More monitors will enter the clinic and become the most commonly used medical equipment in the ward. Therefore, it is very important to maintain and maintain the monitors. Only by doing a good job of maintenance and maintenance can the monitors be in good working condition. At the same time, it can reduce the failure rate, extend the life of various sensors, components and the whole machine, thereby reducing the cost of treatment in the hospital. In summary of previous work experience, the maintenance and maintenance of the monitor mainly has the following aspects:

The monitor usually works continuously for a long time, and it is easy to cause premature aging or even damage to the internal components due to the high temperature inside the machine. Therefore, we must do a good job of cleaning inside and outside the machine to ensure that the machine has good heat dissipation and ventilation. In a few months, check the filter on the main unit and clean the dust on it. At the same time, check the surface of the operation panel and display, and remove the dirt with anhydrous alcohol to prevent corrosion of these important parts. Every six months to one year, the shell of the machine must be disassembled to remove the dust inside the machine. At the same time of dust removal, each module and component in the machine can be inspected by using intuitive methods such as "see, smell, touch". Sensor maintenance and maintenance: Due to the characteristics of the sensor itself and the patient's part being detected are often in motion, it is a component that is easily damaged and an important component that is relatively expensive. In order to extend their useful life and reduce the cost of treatment, we should do a good job of maintaining them. Communicate frequently with medical staff to guide them in the proper operation and maintenance of monitors and sensors. Do not fold or pull the sensor transmission lead; do not drop or touch the sensor's probes such as blood oxygen saturation probes, temperature, invasive blood pressure and other probes. For non-invasive blood pressure cuffs, the host cannot measure at this time when it is not tied to the patient, so as to avoid damaging the inflated airbag. For long-term monitoring of the monitor without monitoring blood oxygen saturation, you can turn off this function by adjusting the system configuration. If this machine has this setting or unplugs the interface between the blood oxygen saturation and the host, the monitor Generally, each sensor is connected through an interface, thereby extending the service life of such sensors. The sensor probe is easily contaminated with various dirt such as sweat and blood stains. In order to avoid corrosion of the probe and affect measurement, the probe should be cleaned regularly according to the method provided in the user manual.

Monitor system maintenance

Improper or even wrong monitoring system settings can often cause problems for healthcare workers. For example: there are ECG waveforms, but no heart rate; blood pressure cannot be measured in patients with hypertension; various parameters are displayed normally, but the alarm keeps on, etc. These may be caused by incorrect system settings. Therefore, the system must be frequently checked and maintained to ensure the reliability and optimality of monitoring, that is, the best configuration. Although there are various monitors and the specific methods of system setting are different, most of them have the following aspects: Patient information In these information, it should be noted that the "patient type" should be selected correctly. Generally divided into adults, children, newborns, they use different measurement schemes, if the wrong choice will affect the accuracy of the measurement, or even unable to measure. For example, non-invasive blood pressure may not be detected and display errors.

Monitor function settings

The best effect is achieved by adjusting the function settings of each parameter. For example, adjust the amplitude and speed to make it easy to observe the displayed waveforms; use various bandwidth filtering functions to eliminate interference at different frequencies such as power frequency and EMG; and set the display channel, system clock, alarm volume, screen brightness, etc. Wait. The alarm configuration correctly sets the upper and lower limit alarm values of each parameter. So as not to cause false negatives. Of course, with the continuous development of the monitor, more new materials and new technologies will be applied to it. We must continue to learn, explore in the work, improve and develop the maintenance and maintenance work of the monitor "

Various brands and models of monitor pictures (8 photos)