By setting limits and establishing a uniform protocol, radiologists can feel secure in administering pediatric sedation for MR scans. In a presentation at the recent Clinical Magnetic Resonance Society conference, Dr. Steven Breiter of Advanced Radiology in Baltimore shared his strategy for why, when, and how sedation should be incorporated into an MR examination in the pediatric population.
Breiter also discussed the results of a program he implemented, tracking over 6,000 MR exams with sedation performed between 1991 and 1997. He spoke at the CMRS conference in San Francisco in June.
"The most important thing is to have a program. You can't just decide that you're just going to do sedation without having thought about it in advance," he said. "It doesn't work safely and you are going to have a bad outcome some day."
Generally, radiologists should only offer conscious sedation to induce calm. Deep sedation, or any level of unconsciousness that may require intubation, should remain in the hands of anesthesiologists, Breiter said.
In addition, sedation should be handled and monitored by the radiology staff from beginning to end. Breiter advised against jump-starting the process by having a parent sedate the child at home.
"I'm strongly opposed to people giving sedation at home and then driving over. This baby is then in a car seat with the head slumped forward," he explained. "The baby falls asleep and it occludes the airway and you can't do anything about it."
Breiter's sedation program consists of six main steps: Pre-sedation screening, consent, pre-sedation preparation, sedation, monitoring, and post-sedation care.
Children between one month to six years are candidates for sedation depending on their general health, level of anxiety, and language skills. A child with good verbal skills may get by on an explanation and conversation alone, Breiter said. Consulting with the patient's pediatrician also can shed light on how apprehensive the child may be.
Based on a risk-classification scale designed by the American Society of Anesthesiology, radiologists are safe in sedating children who are either normally healthy or have a mild systemic disease. Patients who are severely ill or moribund should be managed by anesthesiologists.
RISK-CLASSIFICATION SCALE FOR PEDIATRIC SEDATION
Class 1: Normally healthy patient
Class 2: Patient with mild systemic disease
Class 3: Patient with severe systemic disease
Class 4: Patient with severe systemic disease that is a constant threat to life
Class 5: Moribund patient who is not expected to survive 24 hours
Informed consent is a controversial issue, Breiter conceded, but he added that he always obtains parental consent prior to sedation, which gives him the opportunity to explain the risks and benefits of the procedure.
One drawback of consent is that the parent may agree to the exam, have it arranged, and then have a change of heart, resulting in an empty slot on the MR schedule. But "if you are going to do pediatric sedation, that's (a chance) that you are going to have to live with," he said.
The most stringent protocol dictates no clear liquid four hours before the exam and no solid foods eight hours before. However, Breiter said the rules can be tempered. He recommended clear liquids up to two hours before sedation for any age.
"An important facet is to have a sleepy child before the sedation. I usually tell parents that they should keep the kid up late at night and then wake them up early in the morning. It makes for a tired kid."
Along with a clinical history from the referring physician, a radiologist would do well to undertake a physical review, checking for the following: restrictive air disease in the respiratory system, allergies, GI reflux, dehydration, and anatomic issues, such as a large tongue combined with a small chin. When such a child is sedated in a supine position, the tongue could roll back and obstruct the airway, he said.
The choice of sedation agent is generally based on age, weight, neurological status, and previous sedation experience. Breiter said he preferred either chloral hydrate or pentobarbital sodium. But whatever the drug of choice, he recommended that radiologists avoid experimenting with sedation agents.
"The key is to pick two or three drugs, get comfortable with them and stick to them," Breiter said. "There's no reason to try and learn about all these different drugs."
For children age two or younger, Breiter uses at least 50 mg/kg of chloral hydrate. For children age three or older whose weight-based dosage would exceed the maximum of two grams of chloral hydrate, he opts for pentobarbital sodium.
During pre-sedation, baseline vital signs should be watched. The vital signs, pulse oximetry, and respiratory effort should be checked and followed into the recovery period.
Before the patient is discharged, he or she should be near their normal level of response. Breiter said he checks all the reflexes, including the gag reflex, by having the patient drink water.
Parents should be instructed to keep the patient hydrated. Letting them know that their child will probably sleep for several hours after the exam will alleviate anxiety.
"You can prevent a lot of panic by telling them about residual drowsiness. By the next day, the kid is pretty much back to normal," he said. Parents also should be informed what kind of sedation agent was used for emergency or future reference.
A follow-up call should be made the day after the exam to check on the patient and answer any questions.
Finally, Breiter suggested that radiologists develop a database in order to monitor their sedations. Based on the 6,093 cases logged into his database, Breiter could take note of his technique's strengths and weaknesses. Out of 4,700 sedations, he found only 19 complications. However, during one six-month period, the rate of incomplete exams jumped dramatically when the one nurse trained in sedation left the hospital.
"After that, we had (nurses on rotation) who were not familiar with sedation," he said. "By tracking our experience, we built up a history as a radiology department. We learned where we were failing and where we were succeeding."
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