There was a time when determining how to sedate a child for a CT of the head was a major factor to consider in determining the risk-benefit ratio for obtaining the study. With the speed of today’s new multi-slice CT machines this decision-making process has all but been eliminated. However, as in all other areas of medicine, nothing is ever absolute, and there still are scenarios that will require the sedation of a child for a diagnostic study.
After evaluating this article, participants will be able to:
1. Incorporate strategies into practice for the safe sedation of children undergoing radiological studies
2. Utilize sedative/hypnotic medications safely and effectively in pediatric patients
3. Avoid pitfalls associated with pediatric, procedural sedation
There was a time when determining how to sedate a child for a CT of the head was a major factor to consider in determining the risk-benefit ratio for obtaining the study. With the speed of today’s new multi-slice CT machines this decision-making process has all but been eliminated. However, as in all other areas of medicine, nothing is ever absolute, and there still are scenarios that will require the sedation of a child for a diagnostic study. In addition to the occasional head CT, there are other longer CT studies as well as an increasing number of MRI studies obtained through the ED that will require a child’s cooperation.
Monitoring during procedural sedation is second nature to all emergency department personnel, but it is worth repeating that all patients, regardless of age will require appropriate cardiovascular observation as part of their sedation process. At the very least, continuous pulse oximetry should begin prior to initiation of the sedation process and continue until the patient is fully recovered. Cardiac and blood pressure monitoring are also commonly used for most ED patients. Continuous capnometry is being studied and although it may identify earlier apnea or hypoventilation, it really has not been proven to impact patient outcomes. In most of the studies to date, the capnography did identify hypoventilation, but no actions were taken unless hypoxia actually developed. The one procedure where capnometry may be of value is in prolonged MRI studies where the patient is not in immediate view of any of the staff.
Just as CT scanners themselves have evolved so has the field of pediatric sedation. Gone are the days of one drug fits all. The introduction of newer sedation agents has provided emergency care providers with a wide array of pharmacologic options.
At its core, eliciting cooperation for a CT or MRI involves convincing a child to remain motionless for an essentially painless procedure. In children old enough to understand the concept of a bribe, various deals may be stuck to permit successful completion of the procedure. Distraction techniques may work in younger children for some studies, but for anything longer than a head CT, some type of pharmacologic agent will be required.
Virtually every sedative agent has been successfully used in the management of children undergoing diagnostic studies. For those children in need of emergent imaging, some form of vascular access will already be in place and any of the parenteral sedative agents may be used.
Propofol is the fastest of the IV sedative medications, demonstrating a virtually immediate onset time and a recovery time of 8-10 minutes. For short studies a single bolus 0f 1 mg/kg may be used but for longer procedures such as MRI studies a continuous infusion is better. If a bolus technique is to be used, the drug should be administered just prior to moving the patient from the stretcher onto the CT gantry. This will allow the sedative effect to peak just prior to beginning the study and recovery to begin just after the scanning is completed. (See table)
At the present time the ED formularies offer emergency physicians a wide variety of options for the sedation of children undergoing CT scans and other diagnostic studies. There is no one agent that is the drug of choice for procedural sedation in any particular circumstance. There are only viable options. At left are some of the pharmacologic options and their doses for procedural sedation. (click to enlarge)
Ketamine is another agent that can be used for procedural sedation in a child undergoing a CT study. Contrary to prior beliefs, ketamine does not elevate intracranial pressure and in fact has been shown to be neuro-protective in cases of head injuries. In addition ketamine has evolved as a viable treatment option for patients with status epilepticus. Both of these findings now make ketamine an ideal choice for CT scan sedations in children with acute CNS problems.
Remifentanil is an ultra short acting opioid analgesic with potency equal to that of fentanyl.
Remifentnail has been used successfully for diagnostic sedations, although its more common use is for painful procedures. If used it must be administered as a continuous infusion as its half life is too short to be useful as a bolus injection. Clinical experience with remifentanil has shown that in very agitated children, the drug is less effective but, can be very effective if combined with an anxiolytic dose of lorazepam.
Although the benzodiazepines, and midazolam in particular, are used commonly in adults, their efficacy in children is very limited. Midazolam, in the typical dosing range, has variable sedative effects and in many children has a dis-inhibitory action leading to combative agitated children and frustrated nurses and X-ray techs. For this reason midazolam is not a good choice for the sedation of children for diagnostic studies. In contrast, lorazepam has a more reliable action and can be used for sedation, although it will lead to prolonged sedation.
Pentobarbital is a very reliable sedative agent that is underutilized in the emergency department. Like propofol, this drug has a very rapid onset, on the order of 1-2 minutes, but lasts much longer, up to 2-4 hours. The recommended protocol for this drug is to bring 5 mg/kg to the child’s bedside. Because of its longer duration of action, it can be given with the child still in the ED. Half of the dose (2.5 mg/kg) is given as an IV bolus. The child is observed for 1 minute, but a 3-4 minute observation period is probably safer. If the child is still awake after the observation period ½ of the loading dose is given (1.25 mg/kg) followed by another observation period. If the child is still not adequately sedated the final dose is given (1.25 mg/kg). In clinical practice, that final dose is rarely if ever needed.
Other less commonly used intravenous sedatives that have been described include dexmedetomidine, methohexital, and thiopental.
In some children a parenteral drug may be preferred, even though an intravenous access is not required. In these patients there are a number of very good options.
Intramuscular ketamine and pentobarbital both are reliably safe and effective. Midazolam has been well described as an intramuscular treatment for seizures, but is not commonly recommended for procedural sedation. Diphenhydramine is a very viable option that is not commonly recognized for procedural sedation. Most children, especially those who have been enthusiastically crying will require just a t
ouch of sedation to put them to sleep. (Only emergency personnel can appreciate the image of an enthusiastically crying toddler).
Experience has shown that in these children, diphenhydramine works very well. It should be recognized that all of the cardiorespiratory complications that can occur with intravenous medications can also occur with the intramuscular route. As such, all the monitoring precautions used with IV sedation should be applied to the child receiving IM medications.
In children with painful conditions, subcutaneous morphine will both treat their pain and provide sedation. Morphine is unique in that it is absorbed faster sub Q than IM. This is useful to know, since a much smaller needle may be used for subcutaneous injections than for intramuscular injections.
It should be stressed that a child with a painful condition will require some form of analgesic to cooperate for any procedure. Unless the child’s pain is addressed, either with an analgesic or local anesthetic, the discomfort from the injury will override the effectiveness of any pure sedative. Many of the opioid analgesics produce sedation as a side effect and use of these drugs can address both the pain management issues and elicit cooperation for the diagnostic study.
Oral and Trans-Mucosal Agents.
Oral agents are most commonly used for elective procedures mainly because most emergency personnel are too impatient to administer the drugs and wait for them to take effect.
Midazolam, pentobarbital and again diphenhyramine all will produce effective sedation and sleep within about 30 minutes of administration. As with other routes, midazolam can be variable in it’s action with children.
Chloral hydrate is another viable option for an oral agent for pediatric sedation. That is correct, chloral hydrate. Contrary to prevailing beliefs, chloral hydrate is actually one of the safest and most reliable oral sedation agents for children. In head-to-head studies with other sedatives, chloral hydrate either matches or outperforms these agents. The only limitation with chloral hydrate is that some residual effects can last up to 48 hours, so parents should be warned to maintain close supervision for an extended time following administration of this agent.
Rectally-administered medications have also been used for pediatric sedation. Ketamine, midazolam, diazepam and chloral hydrate have all been used via this route. The results with these drugs have been mixed at best. One drug that is reliably used rectally for sedation is methohexital. Delivered as a solution, it is readily absorbed with sleep generally produced within 5 minutes or less. Because the sedation may be profound with this route, all the general precautions used with the intravenous administration of methohexital apply with the rectal route as well.
Emergency physicians generally do not provide sedation for elective outpatient procedures, but on occasion the EP may need to write such a prescription. In those circumstances, the capabilities of the outpatient facility to properly monitor the child must be assured before even considering out of hospital sedation. At a minimum, a clinician skilled in pediatric vascular access and airway support must be continuously present along with the appropriate age specific resuscitation equipment. The sedative should not be given until the child has arrived at the imaging site. Following completion of the procedure the child must be observed until complete return of all airway and respiratory reflexes. Deaths secondary to airway obstruction while in the car seat on the ride home are well documented in children undergoing outpatient sedations.
One nice technique if it can be arranged is to schedule the test after the child has been sleep deprived overnight. This is a bit challenging for the parents, but if a child can be kept up from midnight until morning, they will generally sleep through whichever test is scheduled at 8:00 am without any need for medications*.
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