Read it in one article! Emergency rescue plan for high field strength MRI operation anesthesia

In the early 1990s, intraoperative magnetic resonance imaging (iMRI) began to be used in neurosurgery, making it possible for neurosurgeons to perform operations under the guidance of immediate MRI
.

Through real-time scanning combined with neuronavigation, it can guide the surgeon to accurately locate the diseased tissue, accurately remove the tumor, protect the nerve function as much as possible, and prevent postoperative complications to the greatest extent

In the early 1990s, intraoperative magnetic resonance imaging (iMRI) began to be used in neurosurgery, making it possible for neurosurgeons to perform operations under the guidance of immediate MRI

However, there are many foreign literature reports on iMRI-related safety issues, such as bringing non-magnetic compatible compressed gas cylinders, wheelchairs, stretchers, and surgical transfer beds into the magnetic field.

Safety risk and zone management of high field intensity MRI environment during operation Safety risk and zone management of high field intensity MRI environment during operation

Safety risks in a strong magnetic field environment

Safety risks in a strong magnetic field environment Safety risks in a strong magnetic field environment Safety risks in a strong magnetic field environment

Intraoperative MRI is a high-risk imaging.
Common risks involve projection effects and biological effects caused by special physical environments such as static magnetic fields, gradient magnetic fields, and radio frequency pulses, which bring unique safety issues, as well as adverse reactions of contrast agents, refrigerant leaks, etc.
fire and noise
.

If not handled properly, it can cause equipment damage, or even casualties

Intraoperative MRI is a high-risk imaging.

According to different magnetic properties, all substances (including metals and alloys) can be divided into two categories:

Ferromagnetic materials: including ferromagnetic materials and ferrimagnetic materials, their permeability is much greater than that of vacuum, such as metallic iron, cobalt, nickel and their alloys and ferrite materials, which can be attracted by the main magnetic field;

Ferromagnetic materials: including ferromagnetic materials and ferrimagnetic materials, their permeability is much greater than that of vacuum, such as metallic iron, cobalt, nickel and their alloys and ferrite materials, which can be attracted by the main magnetic field;

Weakly magnetic materials: including diamagnetic and paramagnetic metals and alloys, their permeability is close to the permeability of vacuum
.

Diamagnetic substances commonly include metallic bismuth, zinc, gold, silver, copper, manganese, mercury, etc.

Weakly magnetic materials: including diamagnetic and paramagnetic metals and alloys, their permeability is close to the permeability of vacuum

Zoning management of high field strength MRI environment during operation Zoning management of high field strength MRI environment during operation

The 2017 edition of the "Consensus of Chinese Experts on Safety Management of Magnetic Resonance Imaging" can divide the range of activities of various personnel in iMRI-OR and DR into 4 areas according to magnetic field strength, use function and safety level:

The 2017 edition of the "Consensus of Chinese Experts on Safety Management of Magnetic Resonance Imaging" can divide the range of activities of various personnel in iMRI-OR and DR into 4 areas according to magnetic field strength, use function and safety level:

Zone I (General Control Zone): This zone includes all completely open areas
.

Zone I (General Control Zone): This zone includes all completely open areas
.

Zone Ⅱ (transition zone): This zone is the place where people can freely enter and exit Zone I and the strictly controlled Zone III
.

Zone Ⅱ (transition zone): This zone is the place where people can freely enter and exit Zone I and the strictly controlled Zone III
.

Area Ⅲ (strictly controlled area): Located outside the 5G line
.

Access to Zone III is strictly restricted, focusing on preventing personnel not related to surgery and inspection and ferromagnetic items/equipment from being brought in

Area Ⅲ (strictly controlled area): Located outside the 5G line

Area IV (core or scanning area): Located within the 5G line, this area is equivalent to the MR scanning room

All anesthesiologists and other staff should receive education on the safety of the MRI operating environment and specific education on the characteristics of the MR equipment used in the hospital
.

The special impact of the high-field MRI system during the operation on the human body

The special effect of the intraoperative high field strength MRI system on the human body The special effect of the intraoperative high field strength MRI system on the human body

Although there is no concern about radiation radiation in the iMRI environment, since the magnet is always in the "open" state, there are still concerns about occupational exposure in this environment for a long time
.
In summary, the impact of high-field-strength magnetic fields on the human body is reflected in:

Although there is no concern about radiation radiation in the iMRI environment, since the magnet is always in the "open" state, there are still concerns about occupational exposure in this environment for a long time
.
In summary, the impact of high-field-strength magnetic fields on the human body is reflected in:

Strong static magnetic field: The strength of the magnet is positively correlated with the field strength of the magnet
.
The body may have some sensory reactions under a strong magnetic field, such as vomiting, dizziness, metallic smell, and magneto-optical hallucinations (short flashes when the eyeballs move quickly), etc.
, which are quite different from one individual to another;

Strong static magnetic field: The strength of the magnet is positively correlated with the field strength of the magnet
.
The body may have some sensory reactions under a strong magnetic field, such as vomiting, dizziness, metallic smell, and magneto-optical hallucinations (short flashes when the eyeballs move quickly), etc.
, which are quite different from one individual to another;

Gradient magnetic field that changes with time: It can cause the human body to generate induced electromotive force, cause some physiological and pathological reactions, produce skin allergies, nerve excitement or muscle twitching, and can produce peripheral nerve excitement (such as tingling or percussion sensation) under sufficient strength.
It even causes heart excitement or ventricular fibrillation in very rare cases;

Gradient magnetic field that changes with time: It can cause the human body to generate induced electromotive force, cause some physiological and pathological reactions, produce skin allergies, nerve excitement or muscle twitching, and can produce peripheral nerve excitement (such as tingling or percussion sensation) under sufficient strength.
It even causes heart excitement or ventricular fibrillation in very rare cases;

The heating effect of radio frequency (RF): During MRI, electromagnetic energy is converted into heat in the body, which increases the temperature of the tissues.
The monitoring wires on the patient's body (such as body temperature, ECG connecting wires, etc.
) can be broken, knotted or too long.
It is overheated and burns the patient;

The heating effect of radio frequency (RF): During MRI, electromagnetic energy is converted into heat in the body, which increases the temperature of the tissues.
The monitoring wires on the patient's body (such as body temperature, ECG connecting wires, etc.
) can be broken, knotted or too long.
It is overheated and burns the patient;

Noise: Various noises (82 ~ 115 dB) are generated during MRI operation.
Sober patients may have irritability, language communication disorder, anxiety, short-term hearing loss, etc.
, which may cause temporary or permanent hearing damage;

Noise: Various noises (82 ~ 115 dB) are generated during MRI operation.
Sober patients may have irritability, language communication disorder, anxiety, short-term hearing loss, etc.
, which may cause temporary or permanent hearing damage;

Contrast agent: The main gadolinium-containing contrast agent used to increase the image contrast may have toxic side effects, such as allergic reactions, liver and kidney damage
.

Contrast agent: The main gadolinium-containing contrast agent used to increase the image contrast may have toxic side effects, such as allergic reactions, liver and kidney damage
.

The basic procedure, safety hazards and treatment of intraoperative high-field MRI anesthesia

The basic procedure, safety hazards and handling of intraoperative high-field MRI anesthesia

iMRI can be applied to all stages of surgery, such as before the operation after induction of anesthesia, during the operation, and after the operation
.
During this period, the anesthesiologist needs to carefully check whether the anesthesia machine, monitoring equipment and the display terminal in the control room are operating normally
.
Adjust the depth of anesthesia according to the patient's specific conditions to meet the conditions of stable vital signs, quietness, and lack of intraoperative awareness during MRI scanning
.
For critically ill patients whose vital signs are difficult to maintain, they should consult with the surgeon, weigh the pros and cons, and decide whether to perform, delay or cancel the intraoperative MRI scan
.

iMRI can be applied to all stages of surgery, such as before the operation after induction of anesthesia, during the operation, and after the operation
.
During this period, the anesthesiologist needs to carefully check whether the anesthesia machine, monitoring equipment and the display terminal in the control room are operating normally
.
Adjust the depth of anesthesia according to the patient's specific conditions to meet the conditions of stable vital signs, quietness, and lack of intraoperative awareness during MRI scanning
.
For critically ill patients whose vital signs are difficult to maintain, they should consult with the surgeon, weigh the pros and cons, and decide whether to perform, delay or cancel the intraoperative MRI scan
.

Various electronic noises in the operating room may affect the quality of the iMRI signal.
In order to minimize the interference of various electrical equipment in the operating room, the AC power of the anesthesia machine, infusion pump, monitor and other equipment may be stopped during iMRI.
Power supply and switch to battery power supply
.
Therefore, it is necessary to ensure that the anesthesia equipment has sufficient power reserve before the iMRI scan
.

Various electronic noises in the operating room may affect the quality of the iMRI signal.
In order to minimize the interference of various electrical equipment in the operating room, the AC power of the anesthesia machine, infusion pump, monitor and other equipment may be stopped during iMRI.
Power supply and switch to battery power supply
.
Therefore, it is necessary to ensure that the anesthesia equipment has sufficient power reserve before the iMRI scan
.

MRI anesthesia operation routine

Routine MRI Anesthesia Operation Routine MRI Anesthesia Operation Routine MRI Anesthesia Operation Routine

1.
Any doctor who undertakes MRI anesthesia must undergo safety screening and there is no MRI contraindication
.

1.
Any doctor who undertakes MRI anesthesia must undergo safety screening and there is no MRI contraindication
.

2.
All doctors involved in MRI anesthesia must be trained and assessed and strictly abide by various management regulations
.

2.
All doctors involved in MRI anesthesia must be trained and assessed and strictly abide by various management regulations
.

3.
The patient must be visited before the operation.
In addition to the routine information, the patient must be informed of the particularity of the MRI and various instructions, and the safety screening form must be filled in and signed item by item
.

3.
The patient must be visited before the operation.
In addition to the routine information, the patient must be informed of the particularity of the MRI and various instructions, and the safety screening form must be filled in and signed item by item
.

4.
Preoperative preparation.
Due to changes in the surgical position, scanning is often performed after anesthesia and head nail fixation.
Especially in the case of temporary decisions, there are often rush preparations.
At this time, the patient's anesthesia is in the adjustment period, and some anesthesia Items in the induction period such as laryngoscopes, stethoscopes, needles and surgical items are easily left in the magnetic field, leading to dangerous situations
.

4.
Preoperative preparation.
Due to changes in the surgical position, scanning is often performed after anesthesia and head nail fixation.
Especially in the case of temporary decisions, there are often rush preparations.
At this time, the patient's anesthesia is in the adjustment period, and some anesthesia Items in the induction period such as laryngoscopes, stethoscopes, needles and surgical items are easily left in the magnetic field, leading to dangerous situations
.

5.
During the operation, a joint safety inspection by surgeons, anesthesiologists, radiologists, patrol and instrument nurses is required, focusing on preventing the omission of instruments at the surgical site, aseptic protection of incisions, control of the depth of anesthesia, microscopes and other non-magnetic compatible items To ensure the safety of scanning
.

5.
During the operation, a joint safety inspection by surgeons, anesthesiologists, radiologists, patrol and instrument nurses is required, focusing on preventing the omission of instruments at the surgical site, aseptic protection of incisions, control of the depth of anesthesia, microscopes and other non-magnetic compatible items To ensure the safety of scanning
.

6.
For patients undergoing scans after surgery, they usually decide to scan temporarily to determine whether there are complications such as severe bleeding, and they are often transferred from the ordinary operation room
.
The anesthesiologist must carry out strict safety screening and notification of patients and other medical staff entering the examination room, focusing on understanding the patient's special medical history, surgical conditions, and special indwellings inside and outside the body after the operation
.

6.
For patients undergoing scans after surgery, they usually decide to scan temporarily to determine whether there are complications such as severe bleeding, and they are often transferred from the ordinary operation room
.
The anesthesiologist must carry out strict safety screening and notification of patients and other medical staff entering the examination room, focusing on understanding the patient's special medical history, surgical conditions, and special indwellings inside and outside the body after the operation
.

7.
In case of emergency, it must be handled in accordance with relevant prompts and plans
.

7.
In case of emergency, it must be handled in accordance with relevant prompts and plans
.

Emergency and handling

Emergencies and handling of emergencies and handling

The possible emergencies in iMRI-OR include: (1) Medical emergencies (such as cardiac arrest); (2) Environmental emergencies (including mechanical failure, fire and object ejection)
.
When a sudden situation (such as cardiac arrest) occurs: ①If necessary, immediately give the patient cardiopulmonary resuscitation and transfer the patient out of Zone IV to a pre-planned safe area near the MRI room; ②Call for help
.
iMRI team members must have the comprehensive ability to deal with emergency situations individually, such as unexpectedly difficult airways, hemorrhagic shock, severe allergies, and cardiac arrest
.

The possible emergencies in iMRI-OR include: (1) Medical emergencies (such as cardiac arrest); (2) Environmental emergencies (including mechanical failure, fire and object ejection)
.
When a sudden situation (such as cardiac arrest) occurs: ①If necessary, immediately give the patient cardiopulmonary resuscitation and transfer the patient out of Zone IV to a pre-planned safe area near the MRI room; ②Call for help
.
iMRI team members must have the comprehensive ability to deal with emergency situations individually, such as unexpectedly difficult airways, hemorrhagic shock, severe allergies, and cardiac arrest
.

The planned safe area should contain the following first aid equipment: (1) Defibrillator; (2) Multifunctional monitor; (3) Emergency vehicle equipped with rescue drugs, airway equipment, oxygen and aspirator
.
This safe area should be selected as close as possible to Zone IV to reduce the delay in recovery
.

The planned safe area should contain the following first aid equipment: (1) Defibrillator; (2) Multifunctional monitor; (3) Emergency vehicle equipped with rescue drugs, airway equipment, oxygen and aspirator
.
This safe area should be selected as close as possible to Zone IV to reduce the delay in recovery
.

Such as fire, catapults and other items to develop appropriate contingency plans for emergencies that may occur
.
Team members must receive iMRI anesthesia training, be familiar with the characteristics and procedures of the work environment, and conduct regular stress plan drills
.
Repeated simulation training
.
The basic procedures and treatments of various medical treatment plans are similar to those of ordinary surgery.
The important and special point is to attach great importance to the particularity of the magnetic field environment, pay attention to safety, and avoid secondary injuries
.
When dealing with emergencies, a staff member needs to be designated to collect blood, deliver surgical and anesthesia appliances, and screen new iMRI-OR staff for assistance
.
For anesthesiologists, special attention should be paid to avoid putting non-magnetic compatible compressed gas cylinders (which may be used when transporting patients) into the magnetic field
.

Such as fire, catapults and other items to develop appropriate contingency plans for emergencies that may occur
.
Team members must receive iMRI anesthesia training, be familiar with the characteristics and procedures of the work environment, and conduct regular stress plan drills
.
Repeated simulation training
.
The basic procedures and treatments of various medical treatment plans are similar to those of ordinary surgery.
The important and special point is to attach great importance to the particularity of the magnetic field environment, pay attention to safety, and avoid secondary injuries
.
When dealing with emergencies, a staff member needs to be designated to collect blood, deliver surgical and anesthesia appliances, and screen new iMRI-OR staff for assistance
.
For anesthesiologists, special attention should be paid to avoid putting non-magnetic compatible compressed gas cylinders (which may be used when transporting patients) into the magnetic field
.

Special emergency treatment:

Special emergency treatment: Special emergency treatment:

(1) Disposal of large magnetic substances (such as gas cylinders, stretchers, wheelchairs, etc.
) adsorbed by magnets
.
First move the patient out of the magnet for placement and proper treatment, and contact the MRI manufacturer as soon as possible
.
If the patient is severely compressed by a large magnetic substance, immediately press the Rundown Unit switch to quench the magnet
.
The magnetic field will be demagnetized after 2 to 3 minutes, and the patient will be removed from the magnet for emergency treatment
.
After the magnet is quenched, it will take multiple working days to resume normal operation, and the maintenance is expensive;

(1) Disposal of large magnetic substances (such as gas cylinders, stretchers, wheelchairs, etc.
) adsorbed by magnets
.
First move the patient out of the magnet for placement and proper treatment, and contact the MRI manufacturer as soon as possible
.
If the patient is severely compressed by a large magnetic substance, immediately press the Rundown Unit switch to quench the magnet
.
The magnetic field will be demagnetized after 2 to 3 minutes, and the patient will be removed from the magnet for emergency treatment
.
After the magnet is quenched, it will take multiple working days to resume normal operation, and the maintenance is expensive;

(2) Disposal of machine failure timeout
.
If there is a patient being scanned, first move the patient out of the scanning room for proper treatment
.
In high-field MRI inspections, a very low temperature is required to maintain the magnetic field, and liquid helium is used to maintain this temperature
.
When a quench occurs and the machine is shut down in an emergency, the liquid helium is quickly heated and transformed into a gaseous state
.
This cooling gas needs to pass through the exhaust pipe and be discharged into the atmosphere.
Once the discharge pipe is blocked, helium is discharged to the inspection area, where low oxygen and high pressure will occur
.

(2) Disposal of machine failure timeout
.
If there is a patient being scanned, first move the patient out of the scanning room for proper treatment
.
In high-field MRI inspections, a very low temperature is required to maintain the magnetic field, and liquid helium is used to maintain this temperature
.
When a quench occurs and the machine is shut down in an emergency, the liquid helium is quickly heated and transformed into a gaseous state
.
This cooling gas needs to pass through the exhaust pipe and be discharged into the atmosphere.
Once the discharge pipe is blocked, helium is discharged to the inspection area, where low oxygen and high pressure will occur
.

The application of iMRI has benefited patients, but the special environment and process have brought certain problems to the perioperative period
.
The smooth development and operation of iMRI-OR requires the full cooperation of team members.
Anesthesiologists are responsible for ensuring patient safety.
Strict regulations, standardized training, good working habits and meticulous intraoperative observations are important for patient safety.
Guaranteed
.

The application of iMRI has benefited patients, but the special environment and process have brought certain problems to the perioperative period
.
The smooth development and operation of iMRI-OR requires the full cooperation of team members.
Anesthesiologists are responsible for ensuring patient safety.
Strict regulations, standardized training, good working habits and meticulous intraoperative observations are important for patient safety.
Guaranteed
.

references

references

1.
Chinese Medical Association of Anesthesiology .
Intraoperative high-field M R the I management expert consensus anesthesia surgery (2020).
Anesthesia safety and quality control , 2021.
DOI: 10 .
3969 /j .
issn .
2096 - 2681 .
2021 .
01 .
001

1.
Chinese Medical Association of Anesthesiology .
Intraoperative high-field M R the I management expert consensus anesthesia surgery (2020).
Anesthesia safety and quality control , 2021.
DOI: 10 .
3969 /j .
issn .
2096 - 2681 .
2021 .
01 .
001 1.
Chinese Medical Association of Anesthesiology .
Intraoperative high-field M R the I management expert consensus anesthesia surgery (2020).
Anesthesia safety and quality control , 2021.
DOI: 10 .
3969 /j .
issn .
2096 - 2681 .
2021 .
01 .
001

2.
The Quality Management and Safety Management Group of the Radiology Branch of the Chinese Medical Association, and the Magnetic Resonance Imaging Group of the Radiology Branch of the Chinese Medical Association .
Magnetic resonance imaging safety management experts from China know [ J ].
Chinese Journal of Radiology, 2017 , 51 (10): 725 - 731 .
DOI: 10 .
3760 /cma .
j .
issn .
1005 - 1201 .
2017 .
10 .
003 .

2.
The Quality Management and Safety Management Group of the Radiology Branch of the Chinese Medical Association, and the Magnetic Resonance Imaging Group of the Radiology Branch of the Chinese Medical Association .
Magnetic resonance imaging safety management experts from China know [ J ].
Chinese Journal of Radiology, 2017 , 51 (10): 725 - 731 .
DOI: 10 .
3760 /cma .
j .
issn .
1005 - 1201 .
2017 .
10 .
003 2.
Quality Management and Safety Management Group of Radiology Branch of Chinese Medical Association, Magnetic Resonance Imaging Group of Radiology Branch of Chinese Medical Association .
Magnetic resonance imaging safety management experts from China know [ J ].
Chinese Journal of Radiology, 2017 , 51 (10): 725 - 731 .
DOI: 10.
3760 /cma .
j .
issn .
1005 - 1201 .
2017 .
10 .
003 .
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