Pediatric Procedural Sedation, Analgesia, and Anxiolysis
Ketamine
Dissociative procedural sedation is frequently utilized in pediatric patients, for which ketamine is usually the agent of choice given its fast onset of action, multiple modes of administration, and robust pediatric safety data. Ketamine is a unique agent because of its sedative, analgesic, and paralytic-like properties. A phencyclidine derivative, ketamine exerts its effect by binding to the N-methyl-D-aspartate receptor, and may be given IM or IV, with usual dosing of 1 to 1.5 mg/kg IV, or 2 to 4 mg/kg IM. Unlike other sedatives, there is a “dissociation threshold” for ketamine, and further dosing does not increase its effects.16
Because of multiple observations and reported cases of airway complications in infants younger than 3 months of age, it is not recommended for routine use in this age group. While ketamine-associated infant airway events are thought by some experts to not be specific to ketamine (and more representative of infant differences in airway anatomy and laryngeal excitability), risks seem to outweigh benefits for routine use in this cohort.16
Ketamine is known to exaggerate protective airway reflexes and can cause laryngospasm, so it is best avoided during procedures that cause a large amount of pharyngeal stimulation. The overall rate of ketamine-induced pediatric laryngospasm is low in the general population (0.3%), and when it does occur, can usually be treated easily with assisted ventilation and oxygenation.17
Prior concerns of ketamine increasing intracranial pressure (ICP) have been shown not to be the case by recent data, which in fact demonstrate that ketamine may instead actually lower ICP.18
For many pediatric centers, including the authors’, ketamine is a first-line agent to facilitate head and/or neck CT in otherwise uncooperative children. Emesis is the most common side effect of ketamine, but the incidence can be significantly reduced by pretreating the patient with ondansetron.19 Though ketamine may also be combined with propofol, there is no robust pediatric-specific evidence showing any benefits of this practice.
Nitrous Oxide
Nitrous oxide (N2O), the most commonly used inhaled anesthetic agent used in the pediatric ED, provides analgesia, sedation, anterograde amnesia, and anxiolysis. It can be given in mixtures of 30% to 70% N2O with oxygen, has a rapid onset of action (<1 minute), and there is rapid recovery after cessation. In patients older than 5 years of age, N2O is usually given via a demand valve system, which will fall off the patient’s face if he or she becomes overly sedated.
Nitrous oxide is usually very well tolerated with few serious events, the most common being emesis.20 Absolute contraindications to its use are few and include pneumothorax, pulmonary blebs, bowel obstruction, air embolus, and a recent history of intracranial or middle ear surgery.
Intranasal Analgesia
Intranasal (IN) analgesics are becoming increasingly popular for pediatric procedures because of their rapid onset of action compared with oral medications, without the need for IV or “needle” access prior to administration.
Intranasal Fentanyl. The EP should use a mucosal atomizer when administering midazolam or fentanyl via the IN route. The atomizer transforms these liquid drugs into a fine spray, which increases surface area, improving mucosal absorption and central nervous system concentrations when compared with IN administration via dropper.21
In a study by Klein et al,22 IN midazolam effectively provided sedation, with more effective diminution of activity and better overall patient satisfaction than with either oral or buccal midazolam. Intranasal midazolam causes a slight burning sensation, and some patients report initial discomfort after administration. The half-lives of IN and IV midazolam are very similar (2.2 vs 2.4 hours).23Intranasal Fentanyl. IN fentanyl is an excellent alternative to IV pain medications for patients in whom there is no IV access. When given at a dose of 1.7 mcg/kg, IN fentanyl produces analgesic effects similar to that of morphine 0.1 mg/kg.
The only reported adverse effect associated with IN fentanyl has been a bad taste in the mouth.24 Another study of children aged 1 to 3 years showed a significant decrease in pain in 93% of children at 10 minutes, and 98% of children at 30 minutes, with no significant side effects.25
Intranasal fentanyl is a great choice for initial and immediate pain control in children with suspected long bone fractures, and is especially useful in facilitating their comfort during radiographic imaging.
Managing a Child for Radiographic Imaging
To facilitate a relatively rapid procedure such as obtaining plain films or a CT scan, anxiolysis, rather than analgesia, is required. Given its quick and predictable onset of action, IN midazolam is an excellent choice for pediatric patients requiring imaging studies. If, however, a mucosal atomizer is not available for IN drug delivery and the patient is already in radiology and requires emergent imaging studies, oral midazolam should not be given as an alternative because of its delayed onset of action. In such cases, placing an IV line and administering IV propofol offers the best chance of achieving quick and effective anxiolysis to obtain the images required to exclude clinically important injuries.
