Sedation/anxiolysis for pediatric imaging

Most pediatric imaging procedures do not require sedation. There are patients, though, who will require some level of sedation in order to obtain a meaningful imaging study. The reasons for sedation are many but include anxiety, painful condition (such as fracture), age of the child (younger children tend to be less cooperative), or study length. Lengthy studies (e.g., extensive magnetic resonance imaging of the brain or spine), studies with painful procedures, children with complex medical conditions in which sedation may be problematic (such as those with cardiac or pulmonary issues), children with tenuous airways or impending airway compromise, or children with medical conditions that the clinician is not familiar or comfortable with should prompt consultation with a pediatric anesthesiologist (or an anesthesiologist who is comfortable and qualified to treat children, including those with complex medical conditions). If such consultation is not available, then consideration should be given to transferring the child to the nearest pediatric facility for the study and further care.

An excellent adjunctive resource to encourage patient cooperation, improve patient comfort, and complete a required imaging study is a child life specialist. Child life specialists use distraction and coping techniques at an age-appropriate level and have been shown to be beneficial in relieving anxiety and increasing cooperation in pediatric patients and to increase family satisfaction with care.

The Guidelines for Monitoring and Management of Pediatric Patients Before, During, and After Sedation for Diagnostic and Therapeutic Procedures state that the goals of sedation are as follows :

• 1.

  To guard the patient’s safety and welfare.

• 2.

  To minimize physical discomfort and pain.

• 3.

  To control anxiety, minimize psychological trauma, and maximize the potential for amnesia.

• 4.

  To modify behavior and/or movement so as to allow the safe completion of the procedure.

• 5.

  To return the patient to a state in which discharge from medical/dental supervision is safe, as determined by recognized criteria.

Training and credentialing for pediatric sedation should be held by all personnel involved in the sedation procedure. Appropriate equipment for pediatric patients should be available, keeping in mind that requirements vary from child to child, with age, weight, and underlying medical conditions and usage during the sedation process being given consideration. The American Academy of Pediatrics (AAP), the American Academy of Dentistry, the American College of Emergency Medicine, and the Society of Anesthesiologists have all issued guidelines and recommendations addressing best practices for pediatric sedation outside of the operating room by nonanesthesiologists. Continuous monitoring before, during, and after the sedation is indicated; monitoring during sedation should, preferably, be performed by personnel not directly involved in the sedation itself. Studies have noted that despite improvement in pediatric sedation practices, there is a persistent rate (although low) of life-threatening events, including apnea, airway obstruction, and laryngospasm.

Patient safety should always be a priority before, during, and after the sedation process. Sedation outside of the operating theater in an emergency department setting is safe and practical, but there are associated risks. Children younger than 6 years of age are particularly at high risk for sedation-related adverse events due to effects on respiratory drive and protective airway reflexes. ^, Clinicians should have the clinical skills necessary to rescue patients from an unintended deeper level of sedation, which can occur in the course of the sedation process. A study looking at sedation and general anesthesia for pediatric patients undergoing computed tomography or magnetic resonance imaging found the rate of hypoxemia to be 2.9% and that respiratory events were more likely to occur in children with an American Society of Anesthesiologists (ASA) class of III or IV. Prompt recognition of an event and intervention occurred, and no children had sequelae as a result of their respiratory event, highlighting the importance of proper training of sedation personnel and the availability of appropriate equipment. Interestingly, this study also highlighted the problem of inadequate sedation in their study population. The quality of the scans obtained was deemed not optimal in nearly one-third (29%) of patients, the time of sedation to the initiation of the scanning procedure was significantly longer, and some imaging procedures had to be rescheduled, contributing to increased cost and inconvenience to the patients’ families due to inadequate patient sedation. The authors proposed the identification of children who are at risk for sedation failure prior to the initiation of sedation and, in these cases, considering general anesthesia for their imaging procedure.

Risk factors for inadequate sedation or failure of sedation include older children, children with higher ASA class, and use of a single agent (benzodiazepines), highlighting that some populations may require general anesthesia. General anesthesia should also be considered in patients with more complex medical conditions (such as congenital heart disease) and in those where the provider is concerned that the patient may be more likely to experience complications from sedation or have inadequate sedation.

Several factors are associated with adverse events and complications from sedation, including inconsistent physiologic monitoring, inadequate presedation evaluation, lack of an independent sedation observer, medication errors, and inadequate recovery procedures. All personnel involved in sedation should have skills in pediatric resuscitation and airway management, specialty-dependent guidelines should be adopted for sedation procedures, and appropriate medications and age-specific equipment should be readily available.

The guidelines promulgated by the AAP and the American College of Emergency Medicine provide general recommendations to help ensure patient safety :

• 1.

  Appropriate patient selection

• 2.

  A responsible guardian (preferably two adults) to accompany the child

• 3.

  Appropriate sedation facility, including personnel and equipment to rescue the decompensating child

• 4.

  Back-up emergency services, if the sedation is taking place outside of the hospital setting

• 5.

  Personnel, medications, and equipment available onsite that is immediately accessible

• 6.

  Appropriate documentation, including informed consent outlining the indications, benefits, risks, and alternative options of the sedation procedure

• 7.

  Documentation before, during, and after sedation. Weight should be recorded in kilograms and any known drug allergies should be noted.

Proper patient selection for sedation is an important step in ensuring safety and a successful sedation experience. While there is no screening test that has the ability to predict sedation complications, there are resources available to the clinician to help guide the sedation process. The ASA classification can be useful to help select which patients are candidates for sedation.

This classification system is not intended to predict risk per se, but increasing ASA classification has been associated with increased perioperative mortality. ^, In the pediatric emergency department setting, an ASA classification of II or higher was associated with a higher incidence of hypoxia. Children who have an ASA classification of III or greater, an anatomy that could potentially complicate sedation (such as Pierre Robin sequence, Prader Willi syndrome, or other craniofacial developmental abnormalities), or any other anatomical or developmental issues should have anesthesiology or subspecialty consultation before sedation. ^{, ,}

It is important that the clinician has a validated, clinically useful method for assessing the quality and depth of sedation for patients undergoing sedation. The AAP, American College of Radiology, and the ASA have adopted four levels of procedural sedation. ^, The Pediatric Sedation State Scale is a widely used measure of the effectiveness and quality of sedation. Parameters such as control of pain, anxiety, movement, and adverse effects were taken into account in the development of this proposed scale. Another useful scale that is simple to apply clinically and has been validated in pediatric patients is the University of Michigan Sedation Scale. ^, Other sedation scales used to assess the depth of sedation include the Observer’s Assessment of Alertness/Sedation scale, which has been validated in children but has limited ability to differentiate between deeper levels of sedation. ^, The Vancouver Sedative Recovery Scale is able to differentiate deeper levels of sedation but is one of the more complex scales available, potentially making clinical application difficult. ^,

Much debate has been made on the necessity of nil per os (NPO) status and the ability to engage in sedation. There are NPO guidelines that are used to determine when it is considered safe to administer various levels of sedation and anesthesia in patients undergoing elective procedures. ^, The concern is whether the risk for aspiration or other adverse event is increased when administering sedation for radiologic or other procedures when a patient has not been NPO for a given length of time. There has been differing guidance among professional societies addressing NPO status and sedation in a setting that is considered more urgent or emergent. ^, A very large study of nearly 140,000 children, conducted by the Pediatric Sedation Research Consortium, examined the relationship of NPO status and aspiration events (defined as an episode of emesis accompanied by a change in respiratory status of the patient or a new radiographic finding). NPO status was known for 107,947 patients, where 25,401 (23.5%) were non—NPO patients. NPO status was defined as no solid food intake for 8 hours, no nonclear fluid intake for at least 6 hours, and no intake of clear liquids for at least 2 hours. Aspiration occurred in 8 of 82,546 NPO patients compared to 2 of 25,401 non—NPO patients. Major complications occurred in 46 of 82,546 NPO patients compared to 15 of 25,401 non—NPO patients. In summary, aspiration was uncommon (<1 event per 10,000 patients) and NPO status for liquids and solids was not an independent predictor of major complications or aspiration. While debate continues regarding sedation and NPO status in the pediatric population and the incidence of aspiration or adverse effects is low, the clinician should consider the indications, urgency, risks, and benefits of sedation for imaging studies.

If the decision is made to utilize sedation in the emergency department or urgent care setting, there are a variety of agents available. Clinicians should be familiar with the indications, benefits, risks, side effects, and pharmacokinetics of whatever agent (or agents) they choose to utilize for sedation and/or anxiolysis. When considering agents, the lowest dose needed with the highest therapeutic index to accomplish imaging should be selected. Long-acting agents are rarely indicated for imaging studies and should generally be avoided. If an imaging study is particularly lengthy, such as magnetic resonance imaging of the brain and complete spine, then anesthesiology should be consulted. Options include analgesic agents, sedative-hypnotic (anxiolytic) agents, and agents in their own categories, such as ketamine, propofol, and nitrous oxide.

Once sedation is completed, patients should be monitored (heart rate, respiratory rate, pulse oximetry, and blood pressure) for return to baseline status. Once patients have returned to their baseline mental and ambulatory status, they may be discharged. Discharge instruction appropriate to the agent and level of sedation used should also be provided to the patient’s caregiver.