Everything There Is to Know About Anesthesia Monitors
The induction and maintenance of anesthesia for a surgical procedure is a complex process that needs solid knowledge and skills. The principle of anesthesia monitoring is simply awareness of all healthy and unhealthy patients' parameters and carefully watching vital signs for any changes. When patients are under anesthesia for surgical procedures, some likely physiological changes could occur regarding the anesthetic drugs used, which directly affects the central nervous system. These changes are monitored by a digital device "anesthesia monitor," which gives a digital reading for all concerned vital signs to track changes regularly and predict any disturbances early in the process. It helps the surgical team have the proper intervention for the patient, restore and keep the patient's vital signs at a healthy level throughout the procedure.
The anesthesia monitor used in the surgery monitor process has specific settings that represent standard vital signs of a patient during surgery. Other tools for postoperative or preoperative monitoring have different configurations, according to the case, the nature of the process, and the patient's conditions. The device includes multiple measuring tools attached to the patient to read and measure the needed parameters like temperature, pulse, oxygen saturation, blood pressure, and an ECG to understand heart functionality. All of them display on a digital screen. They have an alarm system that gives warnings when one or more unpleasant changes occur.
History of anesthesia monitor
In 1950, Himmelstein and Scheiner invented the first physiological monitor device called "Cardiotachoscope" and deployed in surgeries. The cardiotachoscope set the standard and the fundamentals for most future systems; these standards include a CRT to view ECG with automated alarms to detect low heart rates. In the early 1960s, manufacturers started to produce complete physiologic monitoring systems. Top suppliers were Burdick, Birtcher, Dallons, and Air Shields. In 1983, Arrhythmia analysis became available in procedures to help early detection of serious changes in heart functionality.
In the 1990's Siemens SC 9000 was developed to fit both operation rooms and emergency, with a customized configuration for each one.
In the 2000s, Internet connection became available to assist functions in all devices.
Indications to use anesthesia monitor
The monitoring device functions primarily to screen vital signs throughout a surgical procedure.
The main parameters recorded during surgery are:
1- Blood Pressure
Measurement is by an inflatable blood pressure cuff placed around one upper arm.
2- Oxygen Saturation
Measurement is by a small noninvasive device called a pulse oximeter, which is attached to the patient's finger and measures arterial oxygen saturation (SpO2) and heart rate.
3- Heart Rhythm
Measurement is by an ECG, by placing electrodes on the chest, arms, and legs. Then electrodes are attached to a device that translates the electrical activity of the cardiac muscles into a graphical line that is displayed on the screen or printed on paper.
Body Temperature is measured by a temperature probe attached to a thermometer and inserted through the mouth into the conscious patient's esophagus to detect the internal body temperature.
5- Carbon dioxide Saturation
Measured by a device called "Capnography," the capnography system works by sensitively detecting the carbon dioxide concentration in exhaled breath, with warnings if the concentration changes to harmful levels. This process secures an early detection and correction to severe changes in respiration when a patient is under anesthesia throughout the surgery.
Other monitoring systems could be applied depending on the case's needs, the nature of the surgical procedure, the patient's medical condition, and the type of anesthesia used prior and during the procedure (induction and maintenance anesthesia).
Complications of using anesthesia monitor
Generally, the system of surgery monitoring rarely produces complications because of the minimal error profile. However, there could be complications when placing invasive devices in the body; these invasive tools could be:
1- Intra-esophageal temperature probe
The temperature probe needs to be inserted from the esophagus to measure the internal body temperature.
2- Diagnostic catheters
Insertion of catheters into specific arteries or veins to give an accurate measure for blood pressure or to measure heart functions, which needs special cautions in the process of insertion, setting, and removal.
3- Trans-esophageal echocardiograph
It is inserted through the esophagus by a thin endoscopic tube, using an ultrasound transducer, which provides a clear imaging and a full recording for heart functions and a recorded diagnosis throughout the surgery. This technique is needed when lungs and ribs are problematic for the normal echo, and can't give precise imaging.
It is best to perform all the invasive techniques while the patient is sedated under general anesthesia, performed with accuracy, and removed if any life-threatening complications occur.
General specifications of Anesthesia monitor Device
Most monitor brands should have a group of basic requirements to provide the needed functions in the operation room, thus should include:
1- Large and clear digital LED color display
2- Electronic medical record connectivity
3- Storage capacity for data
4- Printing function
5- Blood pressure display
6- Mean arterial pressure measuring capability
7- Heart rates display
8- Dual temperature display
9- Respiration rate display
10-Pulse Oximetry SpO2 connection and oxygen saturation display
These specifications are the bare minimum for a standard vision of a surgery monitor to perform in the operating room. Still, there are other functions that you can add to the anesthesia monitor depending on your needs. Contact the manufacturer and ask for available options and add-ons
Many companies offer full customization for their monitoring products.
How anesthesia monitor works
Surgery monitors work by reading accurate vital signs using measuring devices attached to the patient during a surgical operation. The readings are translated into a digital display which appears on a monitor as graphical lines and numerical readings. The anesthesia monitor is set to configurations to produce alarm warnings whenever one or more parameters are changing dramatically or are not at normal levels. These warnings help physicians make appropriate early decisions and make the needed medical or surgical intervention to correct the problem and avoid complications. These probable vital sign changes are screened wisely for (respiration, circulation, temperature, oxygen saturation, pulse, blood pressure), and other necessary parameters could be added depending on the nature of the procedure. The device is usually connected to EMR to record and document all the data to the patient's medical record, to use it for the post-operation care, and future surgical operations.
The main parameters to be assessed during surgery:
1- Respiratory Parameters
Check regularly that the endotracheal tube is open, continuous, and has no accumulation of fluids
- Respiratory rate, and depth
Healthy Respiratory Rate is 10-20 breaths/minute, normal inspiration lasts up to 1-1.5 seconds, and normal expiration lasts up to 2-3 seconds.
-Oxygen saturation (SpO2)
Healthy Oxygen Saturation level (SpO2) is 95-100%, and this number represents oxygen-saturated hemoglobin, which indicates how lungs are functioning with delivering oxygen to the blood.
2- Cardiovascular Parameters
- Heart rate and heart rhythm
Healthy Heart Rate is 80-120 Beat/Minute. Bradycardia may indicate an excessive anesthetic level or a response to vagal stimulation. At the same time, tachycardia may represent an indication of surgical stimulation.
Heart rate should always be monitored with high consideration to pulse strength and quality.
- Arterial blood pressure:
Normal Blood Pressure is 120/80 mm Hg, and Normal Mean Arterial Pressure is between 70-90 mmHg. A mean arterial pressure lower than 60mm Hg is a red flag and may cause tissue hypo-perfusion. And this sign may indicate excessive anesthetic depth.
3- Body Temperature
4- Anesthetic depth
Market Leaders of anesthesia monitors
1- Infinium Medical
Top Products: OMNI Series
2- Winmate Computer manufacturing company
Top Products: Healthcare Multi-touch Monitor/ Healthcare 4K-UHD Monitor
3- Welch Allyn Medical device company
Top Products: Welch Allyn vital signs monitor 3000 series/ 6000 series
4- Schiller Medizintechnik GmbH
5- GE Healthcare Manufacturing company
6- American Diagnostic Corporation ADG
7- Mortara Instrument, Inc.
It is always essential to know the key standards you need to meet in your operation setting. Choosing the right anesthesia monitor and model can significantly improve clinical outcomes of surgical procedures, minimize errors, and enhance intervention efficacy.
After choosing the right monitor, you should set the configuration according to the place for deployment. Surgical operative rooms require different configurations than the emergency room and intensive care unit.
Secure a regular check and maintenance to the surgery anesthesia monitor device to guarantee a high-end performance and less dysfunction during use. The attachments should be compatible with the monitor specifications and the overall guidelines by your regional healthcare authority standards.
Remember, while assessing patients, the numbers on the screen are essential to be in the normal levels. The small changes may also be an early indicator that the patient's vital signs are on the way to decompensation. Early intervention is critically important to prevent further complications, so do not wait until the parameters give an absolute abnormal value, and screen for changes earlier in the process.