Summary
The provision of anesthesia to children requires unique considerations. The limited airway anatomy, their exceptional reaction to pathology or instruments and therefore possible functional incompetence may be even dangerous during ear, nose and throat interventions. While the anesthetist is physically close to the child at all times during surgery, this “protective proximity” no longer exists after the intervention is complete, although threats to the child’s breathing capabilities continue during the postoperative period. These factors influence modes of anesthesia and the drugs to be used.
Postoperative pain therapy is an essential part of the perioperative care in patients of all ages, and more so in a sick or traumatized child. Appropriate pain control ultimately determines whether or not the outcome will be favorable (complete recovery vs. morbidity and vs. mortality), as well as length of hospital stay, and costs. Otolaryngologic surgery inevitably poses special challenges to the young patient’s ability to cope with upper airway restrictions if inadequate types or doses of analgesics, especially opioids, are used. This also holds true preoperatively, in cases of trauma or selected endocrinologic conditions. Pain assessment in children is thus as essential as it is in adults. However, while verbal and written self-assessments are applicable for grown-ups, pictograms provide a feasible protocol for children starting at 3 years of age. Additional recommended scores have been found reliable pain assessment in younger children, with the aim of replacing or refining the judgment of others regarding the child’s pain status.
This chapter will discuss various aspects of anesthesia and perioperative care in the pediatric population. It will discuss pain expression at various ages, and appropriate drugs and their protocols, adverse events that must be identified and prevented, and modes of age-specified pain assessments.
3 Special Considerations in Pediatric Anesthesia and Pain Control
3.1 Introduction
Children at any age are subject to otolaryngological (ORL) interventions, which are the most common surgeries in this cohort. ENT (ear, nose, and throat) interventions involving the airways may pose life-threatening episodes. These are especially critical because pediatric airways compared to adult airways are smaller and much less robust to resist sudden obstruction. Furthermore, airways of smaller children will react more intensely, and abrupt vagal response may ensue. At the time of the scheduled operation, children frequently suffer from accompanying illnesses such as upper respiratory tract infection (URTI), obstructive sleep apnea (OSA), rhinitis, and various viral infections. These illnesses lead to increased anesthesia risks because of the intensity of their response to anesthetics or surgical stimuli. Pain irritates the respiratory system as well, via its neuro-hormonal and immunological components; the choice of pain management following specific procedures, e.g., tonsillectomy, may be limited. Thus, whenever discussing pediatric ENT anesthesia and perioperative pain control, airway protection is a concern to the anesthetist who needs to walk the child through a safe perioperative process with as little discomfort and pain as possible.
3.2 Perioperative Considerations
3.2.1 Airway Risks versus Safety
ENT interventions are of different types and complexities; even if not emergent ones, they are seldom done in a healthy child. The most frequent operations between the age of 2 and 5 years are auricular paracentesis and adeno- and/or tonsillectomy. 1 Other interventions may include insertion of ventilation tubes, conchotomy, otopexy, tympanoplasty, myringoplasty, and functional endoscopic sinus surgery (FESS). As a rule, surgery that comprises large areas of the face or oral cavity may pose significant risk to the patient’s airways. Oral or facial SOL removal, or trauma, is considered a major surgery in adults as well. These interventions require special attention, including pre-incisional team case-debate, especially in pediatric patients.
The different types of interventions are out of the scope of this chapter; the cardinal anesthesia aspects that are relevant to pediatric ENT procedures are:
Emergency vs. scheduled intervention.
Extensive vs. limited area of intervention.
Surgery that involves or not the child’s airways.
Previous airways status, e.g., chronic URTI, asthma, whizzing, or external treatment (irradiation).
These outlooks will be briefly highlighted as the discussion proceeds.
Airway control is a top priority in the child. From the anesthesia point of view, the following circumstances are valid a s absolute contraindications for ambulatory otorhinolaryngology (ORL) operations: 2 – 5
Chronic comorbidity with unstable course.
Disease with need of prolonged monitoring.
Increased risk of postoperative bleeding.
3.2.2 Detriments in the ENT Pediatric Population
Common causes are the URTI that are viral infections (e.g., rhino-, corona-, influenza, etc.). The invasion of the virus into the epithelium and the mucous membrane of the respiratory system leads to an inflammatory response, followed by edema, excessive secretions, containing tachykinins and neuropeptides, and bronchial (smooth muscle) constriction (“bronchial hyper-reactivity”). There is characteristic hyper-reactive response of the respiratory tract to endotracheal tube (ETT) insertion and to volatile anesthetics, e.g., desflurane. 6 At the same time, a major advantage of desflurane over other inhalational agents is that its blood-gas partition coefficient (0.42) is lower than the others’, predicting rapid induction and recovery from desflurane-based general anesthesia (GA). However, due to the above-mentioned airway irritation, possibly leading to breath holding, coughing, excessive secretions, and laryngospasm, 7 its use in such subpopulation is not recommended.
The “airway susceptibility” is characterized by productive cough, purulent secretion from the nose, shortness of breath, and fever, all causing perioperative respiratory adverse events (AEs), 8 lasting >6 weeks. Neither blood count nor acute phase parameters, such as C-reactive protein (CrP) or procalcitonin (PCT), are of value in predicting the outcome of an infection or perioperative complication risk. 2 , 9
There are potential characteristic risks for respiratory AEs:
Patient influences:
Age: Younger kids are more susceptible than older ones; history of premature birth is an additional factor.
Associated respiratory illnesses: URTI ≤2 weeks, recurrent wheezing, current/past asthma, nocturnal dry cough, wheezing during exercise, hay fever, current/past eczema, family history of asthma, and passive/active smoker are all deteriorating issues.
Other Bronchopulmonary diseases: Bronchopulmonary dysplasia (BPD), cystic fibrosis.
Diverse pathologies: Previous history of apnea, OSA, obesity, syndromes associated with airway obstruction (e.g., Down syndrome), anemia (hematocrit <30%), unfasted patient.
Surgical factors: Shared airway procedures (e.g., ENT + dental + upper airways); blood or secretions present or expected in upper airways; sudden surgical stimulation; emergency procedure.
Anesthesia-related factors: Premedication with benzodiazepines (BZD) (e.g., midazolam); topical airway use of lidocaine; inhalational induction of anesthesia; invasive airway management (ETT > laryngeal mask airway [LMA] > facemask); less experienced anesthetist with airway management; insufficient supervision ratio for trainees (e.g., supervisor absence during critical periods of anesthesia); desflurane administration; high-dose opioid administration; administration of neuromuscular blocking agents; low nurse-to-patient ratio in the recovery area (<1:1); mixed anesthetic clinical practice (adult/pediatric > solely pediatric). All these are to be considered perioperatively by the anesthetist. 10
3.3 Perioperative Anesthesia Considerations in the ENT Child
The following few safety key points in the ENT pediatric population are worth memorizing:
In the spontaneously breathing child, if respiration is not disabling/dangerous, it is best to secure ventilation and oxygenation until the anesthetist takes over.
Avoid excessive BZDs and opioids pre- and postoperatively so that respiration and cooperation are reduced.
Always titter analgesia; always monitor drugs’ effects.
ENT perioperative anesthetic and pain considerations in the pediatric cohort will be discussed for the following three specific periods:
Preoperative evaluation and preparation for anesthesia.
Intraoperative anesthesia/analgesia regimens.
Postoperative patient-tailored adequate pain treatment and prevention of AEs.
The reader is referred to a detailed review regarding perioperative anesthesia considerations. 11 In their Clinical Practice Guidelines for Pediatric Tonsillectomy of the French Society of ENT and Head and Neck Surgery (SFORL 2009), the authors highlight aspects that reflect outcome, starting with the appropriate indications for tonsillectomy, and the eventuality of OSA, all during the preoperative assessment. The surgical techniques to be used are important, as well as the intervention being performed in an in- or out-patient facility, modes of postoperative follow-up, and how to manage complications.
3.3.1 Preoperative Evaluation and Preparation for Anesthesia
Any patient requiring anesthesia is subject to physician-patient interview, physical examination, auxiliary testing if necessary, and explanatory discussion, all taking place before obtaining the patient’s consent. All preoperative phases of preparation of the child involve parents’ or guardian’s participation. Indeed, the intimate relationship between the two affects the overall acceptance of the unfamiliar and frightening environment and refusal expressible by the child. Thus, psychological (= non-pharmacological) and pharmacological approaches are essential for the smooth transition of the child from his known, secure, and loving surrounding into an unfamiliar environment that may upset the child.
Standardized Provision of Detailed History
This is the most important screening instrument used to prepare patients for anesthesia. 12 Earlier reports have offered various standardized questionnaires; they are helpful, sometimes even essential. Besides providing information regarding organ dysfunction, allergies, passive smoking, previous exposure to anesthetics, and their eventual consequences, parents need to also provide relevant behavioral and medical information about the child. 12
Important issues relevant to the operated child are obesity and metabolic syndrome, which represent problematic current public health issues worldwide. In a recent National Health and Nutrition survey, it was suggested that 17% of the children and adolescents in the United States are obese and overweight, 13 – 15 compared to ~20% of the European obese and overweight children. 16 , 17 The WHO defines pediatric overweight and obesity according to standard deviations (BMI Z-scores) from the mean adult BMI values, whereas the United States defines BMI ≥85th percentile as overweight and BMI ≥95th percentile as obesity. 18 Pediatric obesity is a special challenge to the anesthetist mainly due to respiratory, pharmacological, and metabolic changes. 19 , 20
Physical Examination
This should focus on signs and symptoms that may be relevant to anesthesia, above all the respiratory and cardiac systems, with emphasis on auscultation. Since ENT surgery may involve the upper respiratory system, particular attention should be paid to its examination. The anatomy of the face and the skull should also be considered. It is important to allow the child to have a break when possible, in-between examinations, which would minimize confounding information and excessive agitation. It is highly advisable to conduct the exam while the primary caregiver stays next to the child. Early team sessions, and meetings with the guardian who delivers informative and behavioral experiences, are essential. 21 – 23
History of Bronchial Asthma and URTI
Asthma is the most common condition in childhood that warrants particular attention, and therefore meticulous questioning and auscultation. Preoperative X-ray of the lung is not diagnostic in children with asthma. 24 Existing algorithms help in individual decision when an intervention should be postponed in a child with URTI/asthma, and for how long. 6 , 8 , 25 Briefly, in the presence of watery or purulent congestion, and where airways are not involved during surgery conducted by an expert or ETT is not part of the surgical plan, one may proceed. If fever or malaise or purulent congestion is detected, that is where risks overweigh benefits, surgery should be postponed for 10 to 14 days and the child then re-examined. Recent (<30 days) asthmatic breakthrough and pulse therapy need to be analyzed individually; airway functioning and breathing conditions must be thoughtfully evaluated before a decision is made. This is because non-emergency pediatric interventions, especially ENT ones, are dangerous, possibly lethal, if performed during periods of airway irritation. Systemic steroid pretreatment for asthmatic patients, especially those treated with systemic steroid within previous 6 months, was suggested upon intervening for nasal polyp, otolaryngological and oral surgery. 26 These children should not be operated under ambulatory conditions.
Obstructive Sleep Apnea (OSA)
The obese child is another concern for the anesthetist. 27 Adenotonsillectomy (ATE) is one of the most frequent surgical interventions in children with OSA. 28 This combination of illnesses still lacks guidelines and recommendations of care. 29 The risk for postoperative hypoxia 30 and the known increased sensitivity to µ-receptor-agonist opioids 31 are to be judiciously considered in all children, especially in those suffering from URTI, OSA, or obesity. In a pilot study aiming at identifying perioperative risk factors for respiratory complications in children with ATE with heavy OSA, the presence of only 1 out of 4 risk factors led to an increase in ~35% of complication rates vs. children without any risk. They require strict follow-up and preoperative preparations if factors are known by history. 32 The above-mentioned 4 risk factors are:
Age < 2 years.
Intraoperative laryngospasm or other airway reactions.
Postoperative occurrences of SpO2 <90%.
Apnea-hypopnea index (AHI) >24.
Interval between Vaccination and Intervention
There are currently no evidence-based recommendations regarding such intervals. 33 Common clinical attitude recommends 5- to 7-day interval.
Blood Sampling
Blood sampling induces considerable stress in the child; it should be carried out only when necessary. 34 Indeed, a systematic review found that routine laboratory examinations deliver no additional information after a conscientiously carried out history or clinical examination that showed no pathologies which would influence the anesthetist’s decision-making. 34 Nevertheless, preoperative evaluation of the hemostatic and coagulation system is crucial in ORL patients, in order to minimize the risk of postoperative bleeding. The most common coagulation pathology in childhood is the autosomal dominant inherited von Willebrand syndrome; 35 , 36 specific consultation is warranted. Finally, for those with known or newly onset cardiac disease, the anesthetist should consult a pediatric cardiologist before final decisions regarding surgery and anesthesia are taken. 12
3.3.2 Trauma Patients
Trauma to facial soft tissue or bones, infection, or SOL involving facial muscles or oral cavity frequently limits the opening of the mouth, and may obstruct air passage through the glottis, mainly due to inflammation, edema, and hemorrhage, and may induce trismus of the masseter muscles (tonic contraction of the muscles of mastication, “lock-jaw”). Myofascial pain syndrome (previously known as myofascial pain and dysfunction syndrome [MFPDS]) may follow spasm of the masticatory muscles (medial, internal and lateral, or external pterygoids, temporalis, and masseter). Such pain may also intensify trismus. The limitation in opening the mouth is a “warning sign” to any sort of deep uncontrolled sedation—not analgesia, which, if adequately administered, rather moderates these pain-potentiated phenomena. The current practice to rely on the Mallampati score is better played down in such cases because unexpected airway obstruction may hide beyond an incomplete oropharyngeal opening.
Upon attending those admitted to the emergency department (ED), a quick, safe, multi-task, and integrating approach would enable appropriate analgesia and diagnostic procedures before further decision is made. Under these circumstances, maintenance of spontaneous breathing is the rule of thumb during any analgesic treatment. The best mode of sedating and reducing pain is the use of a safe pharmacological approach that would comfort the child, and minimize refusal, like during the placement of an IV line (if not placed by pre-hospital staff). In case the child does not allow it because of fear or anxiety, or is uncooperative for any reason, it should be corrected immediately, except when those are signs of hypoxia. LA paste (e.g., Emla cream, a lidocaine and prilocaine topical compound) is worth applying to the back of the hand/foot, so that a few minutes later a vein can be painlessly accessed. This would allow not only injecting measured doses of medications, but also administering fluids if necessary. It is recommended not to use large doses of BZDs or opioids IV in face/oral traumatized or burnt children, especially those who require ED observation or transfer to the imaging department. As mentioned below, rectal (PR), sublingual, or intranasal (IN) administration of drugs (e.g., ketamine) is worth using in the absence of an IV line. 37 Drug titration that aims at reaching a low grade of sedation—where the child is calm, painless, and arousable—is best, provided oxygen is supplemented, SpO2 is monitored, and an anesthetist/pediatrician monitors the patient all the way from the time the sedative is administered to the induction of anesthesia or panned awakening. An airway device and a laryngoscope must be placed next to any sedated ENT patient.
Oncological Interventions: Anesthesia Considerations
Tumor of the superior chest, the thymus, or surrounding lymph nodes can easily compress the superior vena cava, causing venous stasis. Signs of superior vena cava syndrome (SVCS), including swelling and cyanosis of the upper body, and symptoms of the superior mediastinal syndrome (SMS), associated with cardiopulmonary stress or dyspnea and cough, dysphagia, orthopnea, and hoarseness, although none are of acute severity, may worsen respiration following sedation or analgesics administration. Tracheostomy may be necessary—and therefore tools should be ready for use—if optimal ventilation or oxygenation require assisted ventilation obtainable via ETT or LMA.
The presence of a tumor in the oral cavity or near the airways, or a history of past or recent radiation therapy to the head, face, or neck, is risky to the patient’s life. 38 Effects of past head or neck irradiation include fibrosis and stiffness of soft tissues, which can lead to limited mouth opening, neck extension, or oropharyngeal manipulation. Such chronic (or recent) changes also may include airway mucosal fibrosis, chronic subglottic edema, supra- and subglottic narrowing, or stenosis, growth retardation of cartilaginous structures of the larynx or hypoplasia of the jaw in children of any age, xerostomia, and chondronecrosis of the epiglottis, the arytenoids, and the trachea. 39 – 41 These medical records require full attention of the teams; imaging of the areas is an essential source of information and provision of safety data, so that the anesthetist may not be surprised and the child endangered upon inducing GA.
Since radiation habitually alters neck anatomy, thus affecting airway management, Delbridge et al 41 reported that smaller ETTs than those predicted (by age and weight) were required in adults whose neck had been irradiated in infancy, due to significant tracheal stenosis. Giraud et al 42 reported of the use of LMAs in adults who had earlier received oral or cervical radiotherapy. The authors found a high rate of restricted mouth opening as well, difficulty with LMA insertion, and laryngeal collapse, making ventilation with an LMA difficult or even impossible. Specific complications in children, however, have not been reported, probably because such outcomes after irradiation require time to develop. Nevertheless, when caring for a child who has undergone radiotherapy to the neck, similar potential airway difficulties must be kept in mind during preoperative examination and upon inducing anesthesia to the patient. Psychological preparation of the child and the guardian (see below) enables focusing on the consequences and their correlates in this subpopulation.
High-dose chemotherapy and total body irradiation (TBI), as for hematopoietic stem cell transplantation (HSCT), may cause mucositis of sufficient severity to jeopardize airways’ patency, because of pseudomembrane formation, supraglottic edema, bleeding, and aspiration of blood and secretions, all contributing to malfunctioning airway reflexes. 43 , 44 When discussing how to manage the airways, 44 besides the need to have their clear picture, one needs to avoid airway trauma and maintain the oral mucosa constantly wet. 38 Even when mucositis is not severe, radiation therapy, glucocorticoids, chemotherapy, and chronic graft versus host disease (CGVHD) that are often combined can provoke airway mucosa damage because of its friability. All these need to be reported and evidenced preoperatively, much before instrumenting the airways. The oral cavity and dental areas should be handled in a precautious and highly attentive manner. 45 The original lesions and those following instrumentation generate soaring pain that needs attention preoperatively. Patients should be kept in hospital for a judicious postoperative surveillance.
Endocrine and Neuroendocrine Tumors
These tumors include thyroid tumors (30%, adenomas and carcinomas) and pituitary tumors (20%, craniopharyngiomas and pituitary adenomas). Carcinoma of the thyroid usually presents with a single thyroid nodule. 46 Craniopharyngiomas, which are the most common pituitary tumor, frequently cause headaches, visual disturbances, and pan-hypopituitarism, including diabetes insipidus. 47 The former may affect free approach to the airways; they need to be evidenced by X-ray of CT, whereby description of airways format and exact width of the trachea need to be obtained preoperatively.
The use of corticosteroids is discussed next.
Preoperative Decision-Making
As occurring in adults, surgery may accompany decisional conflicts among the medical staff, parenteral uncertainty, and the fear from negative consequences, so that emotional distress and delays in decision-making at any step of the course may come up. 48 Interestingly, a decisional regret may reflect earlier postoperative complications. 49 , 50 Shared decision-making is thus recommended to improve quality of care and satisfaction, as well as patient’s or parent’s anxiety, decreasing the health care system costs as well. 48 – 52
It is therefore relevant that while patients and caregivers should provide medical history and health details minutely, they should also be provided with all information and instructions regarding the nature of the procedure, benefits, risks, and expected postoperative course of the intervention. Discussion of anesthesia details, including tracheostomy, when applicable, involves perioperative emotional support that should be provided to patients and families; a preoperative meeting with a communication and/or feeding specialist for post-interventional rehabilitation may then be necessary as well. 53 , 54
Fasting Regulations
Guidelines for preoperative fasting times before elective interventions are currently well defined: 12 , 55 – 57 6 h for food, 4 h for milk/breast milk/formula diet, and 2 h or less for clear liquids (water, tea, clear juices, lemonade). The latter option (≤2 h) positively affects the child both physically and psychologically.
Non-Pharmacological Preoperative Preparation
Periprocedural psychological evaluation is essential in the pediatric population. When supporting their children perioperatively, 58 parents sense helplessness and are anxious; these are transmitted to their children (of any age). 59 Parents’ coaching and application of emotional pre-interventional preparation are therefore of positive potential benefits. 60
Specific methodologies, inducing psychological embracement, that aim at reducing mothers’ and children’s built-up fear are beyond the scope of this discussion. It is, however, essential to point out that these are to be addressed before surgery, thus avoiding untrue promises to the child or parents. 53 , 54
Pre-interventional preparation of the mature, and even the less mature, child, by visual description of the interventional steps decreases the stress and anxiety associated with the procedure. This should be performed in a quiet environment, with the availability of cognitive-behavioral interventions among participants. If the child is hospitalized, the meeting should be held away from the child’s room. 61 Explanations and illustrations of postoperative pain and the ways to control it are an essential component in this gathering.
Based on the case, every anesthesia team must decide for itself regarding whether anesthesia should be induced in the presence of the parents or not. While no clear clinical advantage has been evidenced using this approach, 62 , 63 the Modified Yale Preoperative Anxiety Scale has shown that children who were allowed to be accompanied also by a clown showed significantly lower anxiety scores. 64 These opportunities should be discussed with the child preoperatively.
Preoperative Pharmacological Preparation
Preoperative pharmacological approaches aim at coadjuvating the mother-child tranquility, thus strengthening the child’s confidence and acceptance of the sites of intervention (emergency medicine, operating room [OR], day-care area, or out of the OR suite). It has been proven that a calm child is accompanied by a calm parent, the latter reflecting on the former’s behavior and vice versa. While explanations, discussions, and assurances can generate calm and cooperation, and a grown-up child can also benefit from them, pharmacological aid will optimize the child’s serenity. The pharmacological approach consists of various sedatives administered ahead of the time of the intervention, titrated to the desired stage of tranquility while communication is preserved and vital functions remain unaffected. Importantly, if preoperative pain is present and is scored high by the child, its control is an integral part of reduction in tension and hindrance. Noteworthy is the fact that combining drugs of various neuropharmacological activities may potentiate each other; this may be undesired, and the child’s surveillance is necessary while cautiously augmenting the doses. 65
It has been stated that more than 3 weeks of exogenous corticosteroid therapy (>20 mg/d prednisone or equivalent) can produce measurable suppression and inability to self-generate stress response for up to 1 year. 66 Although the need for, and benefit of, intraoperative “stress dose” corticosteroid therapy has been questioned, 66 – 70 preoperatively obtaining the history of dosage, duration, and last use of exogenous corticosteroids is warranted. With this information, the anesthetist can better decide whether a stress dose of steroids will be necessary. 66
Variable lengths of glucocorticoid-induced adrenal suppression have been reported in the pediatric oncology literature as well, 71 – 77 ranging from 2 to 8 months. Such a variance may reflect varying glucocorticoid protocols, doses, and tapering protocols. In a study of 24 children who were treated with prednisolone, persistent adrenal suppression was measured in 46% of the cohort at 2 weeks, and 13% of children 20 weeks after cessation of prednisolone. 75 The stress response being unpredictable, steroid coverage need to be provided during stressful conditions 1 to 2 months after cessation of glucocorticoids. 71 The usual replacement regimen is 1 to 2 mg/kg of hydrocortisone (Solu-Cortef) or of dexamethasone (0.05–0.1 mg/kg) IV. 78 Preoperative multidisciplinary consultation should therefore be held to decide perioperative use of corticosteroids. 61
Premedication
Various drugs were found efficacious in lessening children’s anxiety in the pre-procedural period. Best sedative status is attained after IV/PR/IN/intraoral bolus administration of certain drugs: the effect is achieved almost immediately, where the degree of needs vs. effects and the duration of action are timely pre-determined. Unlike past use of oral drugs (e.g., chloral hydrate, diazepam), whose clinical sedative effects were long and unpredictable, current protocols provide pharmacological certainty as well as patient’s safety. Following are few examples.
Midazolam
This is a short-acting anxiolytic, which can be administered either IV/IM, orally, rectally, or intranasally. 79 , 80 Nevertheless, midazolam has recently been challenged due to both the amnesic and undesirable cognitive postoperative effects it may induce, 81 and increased risk of post-sevoflurane agitation (when combined). 82 , 83 The use of the drug remains at the anesthetist’s discretion.
Alfa2 Agonists
Clonidine is rather a viable alternative: 84 it produces better early postoperative pain relief (especially when combined with other analgesics), and reduces shivering and postoperative confusion and agitation compared to midazolam. 85 Furthermore, similarly to its handling in adults, IV BZDs (mostly midazolam) are currently rarely used preoperatively, rather intraoperatively.
When pre-ENT procedure MRI is required, although the procedure is not painful but lasts relatively long, and there is need for a calm and immobile patient within a tunnel-like apparatus, and where noise may annoy or frighten the child, some sedation is warranted. Parents are rarely permitted to stay aside the bed during the entire examination. The efficacious use (infusion) of dexmedetomidine, an alfa2 agonist, has been reported to cause no delay in discharging the child home. Besides within-the-normal-range slight changes in blood pressure (BP) and heart rate (HR) induced by the drug, no other untoward effects were noted, particularly those related to respiration and maintenance of patent airways. 86 – 89 It also provides an opioid-sparing effect and lowers emergence delirium compared to other drug combinations. 90 Comparatively, CT imaging is currently an ultra-short procedure so that children can be left alone for a very brief period and may need no sedation, unless uncooperative. Finally, the unwanted effects of dexmedetomidine may include initial hypertension, hypotension, and rare nausea, bradycardia, atrial fibrillation, and hypoxia, all occurring mostly during or shortly after the drug’s loading dose and depending on its rate of infusion. 91 Such overdose may also cause first- or second-degree atrioventricular block (AVB). Nevertheless, it was reported at a dose 60-time higher than the prescribed dose that was infused to a small child (<6 month) for 1 h during imaging. No hypotension, hypertension, and changes in HR or in respiration/oxygenation were noted. Safe discharge was delayed by 2 h after discontinuation of the infusion. 92 Dexmedetomidine exhibits linear kinetics when infused in dose ranges of 0.2 to 0.7 µg/kg/h for <24 h (as approved by the FDA). For pharmacokinetics and dynamics of the drug see; 93 doses are specified in ▶ Table 3.1.
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