【Topics in Pediatric Anesthesia】Application of MRI Technology

MRI technology application The human body is very rich in water, and different tissues have different water content
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MRI technology is a technology that detects the internal structure of the human body by identifying the distribution of hydrogen atom signals in water molecules
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The MRI instrument will provide two gradient magnetic fields perpendicular to the main magnetic field, so that the distribution of the magnetic field in the human body will change with the change of the spatial position.
Each position will have a magnetic field with different strengths and different directions.
In this way, hydrogen atoms located in different parts of the human body will respond to different radio frequency field signals.
By recording this response and performing calculation processing, the information of the distribution of water molecules in space can be obtained, thereby obtaining images of the internal structure of the human body
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MRI technology is a non-invasive detection technology.
Compared with X-ray penetration technology and radiography technology, MRI has no radiation effect on the human body.
Compared with ultrasonic detection technology, MRI is clearer and can display more details.
In addition, compared with other imaging technologies , MRI can not only show tangible solid lesions, but also can determine the functional changes of the brain, heart, liver and other diseases
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Due to different principles, the contrast of CT imaging of soft tissue is not high, and the contrast of MRI imaging of soft tissue is much higher than that of CT
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This makes MRI particularly suitable for imaging brain tissue
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There are no biological adverse effects directly caused by MRI magnetic fields, but the strong magnetic fields necessary for MRI have the potential to create several serious dangers
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The most significant effect in the MRI cabin is the effect of the magnetic field on the associated objects
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Rejection of implanted biological devices and other ferromagnetic components poses a related hazard
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There are several problems in providing sedation or anesthesia for children undergoing MRI examination: (1) the operator is not easy to access and directly observe the child, especially when examining the child's head; (2) ferromagnetic objects need to be completely excluded; (3) The strong magnetic field and changes in RF current cause the monitoring equipment to be interfered or malfunctioned, and the usual anesthesia machines and monitors cannot be used in the cabin; ④ Emergency personnel can enter the cabin, but their activities are restricted
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Some manufacturers produce MRI-compatible anesthesia machines
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Various breathing circuits have been successfully used in MRI chambers to support breathing with MRI-compatible ventilators
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Due to the inaccessibility of the child's airway during MRI scanning, the limitation of the magnetic hole, and the influence of the loud noise during the scan, the evaluation of the child is limited, so deep sedation/analgesia is not recommended
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MRI does not require special anesthesia techniques, MRI examinations are not very painful, and solid drug regimens tend to be moderately sedated
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Introduced several plans in our hospital for children who are going to undergo MRI examination to go to the sedation center for pre-examination evaluation, and determine the choice of sedation plan and explain the precautions with their families
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Precautions In addition to the risk of anesthesia outside the operating room, there are also special properties of magnetic field work, such as whether body implants can be assessed for inspection
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Newborns, premature infants 1.
Newborns, premature infants, 1 to 3 months old children can generally complete the examination by themselves by sleep, and sometimes they can be assisted by wrapping to increase the sense of security of infants and young children
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Chloral hydrate 2.
Oral or enema chloral hydrate is suitable for children who are less than 20kg.
According to the examination, sleep deprivation (ex.
8 point examination, sleep at 12 o'clock later, get up at 5 o'clock) fasting is not specially emphasized, but eat less
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Don't fall asleep without checking
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20 minutes before the examination to the enema room to prepare the enema
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Ask the family members of the patient to hug and sleep
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Observe the child's lip color and whether the drug is discharged from the anus
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After falling asleep, simple monitoring of SPO2 was performed, and the examination was performed when it was confirmed that the child was in deep sleep
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Oral bitter and spicy taste is generally unacceptable to children
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However, the enema has anal stimulation, and the rectal reactive contraction has a high probability of expelling the drug
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The literature on this protocol reports mixed success rates
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Through the cases in our hospital, we can only say that sleep deprivation and eating less can improve the success rate
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Propofol 3.
Intravenous use of propofol is suitable for children with unsuccessful enema, no recent severe pneumonia, and airway difficulties to be excluded
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Before the examination, the fasting water was prescribed according to the requirements of the fasting water before the operation
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The MRI examination room of our hospital is equipped with corresponding degaussing monitoring and anesthesia machines to ensure safety
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The examination technician will also place a breathing sensing device in the abdomen, and the anesthesiologist can see the breathing wave of the child.
If a long-term examination is required, there are corresponding extension tubes and infusion equipment
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This program has a high success rate, almost 100%
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Midazolam 4.
Oral midazolam has recently been carried out in our hospital.
The fasting water is the same as the preoperative fasting water requirements, and there is no additional opening of peripheral veins, which is highly accepted by parents
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The success rate is currently observable
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JUST ENJOY THE LIFE is a simulated nuclear magnetic room toy house in our hospital, which has the sound of nuclear magnetic operation when scanning the code, and allows the older children to adapt to the environment.
JUST ENJOY THE LIFE is a recovery room specially set up for nuclear magnetic resonance
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Reference Books: Selected Typical Cases of Pediatric Surgery Anesthesia Editor-in-Chief Zhang Jianmin Notes: Wu Yajun Typesetting: Rou Rou — END —