5: Topics in Pediatric Physiology

Topics in Pediatric Physiology

The treatment of children presents particular challenges to the health care professional. The body of the pediatric patient is not simply a miniaturized version of his or her adult counterpart; child physiology and anatomy significantly differ from that of adults. Pediatric dentists must consider these differences when making therapeutic choices about young patients, especially when treatment includes drug therapy. Route and rate of drug administration, dosage, onset and duration of action, and possibility of toxicity all are influenced by the unique physiology of childhood.

This chapter will review basic principles of pediatric physiology—including pharmacokinetic characteristics—and anatomy. For the sake of simplicity, the material will be presented by organ system. Because a comprehensive review of these subjects is beyond the scope of this chapter, the text stresses only the principles that differ significantly from those of the adult patient. Wherever possible, clinical applications to pediatric dentistry are made.

Respiratory System (Figure 5-1)

Anatomy

Several anatomic features of the pediatric respiratory tract predispose the young patient to obstruction and collapse of both large and small airways. A child’s upper respiratory tract is prone to obstruction at several sites. The narrow nasal passages, tongue/oral cavity disproportion, and decreased airway diameter characteristic of infants and young children predispose this patient population to partial or complete upper airway obstruction (Figure 5-2).1,2 Additional risk may be generated by routine office procedures: a tightly clamped mask over the nares, a mouth pack depressing the oral cavity floor, or a retractor posteriorly displacing the tongue all may increase the likelihood of upper airway obstruction. The secretions and edema associated with upper respiratory infections also can compromise the pediatric airway and should be kept in mind when an acutely ill child reports for an elective procedure. Bronchospasm, laryngospasm, acute subglottic edema with stridor, intraoperative and perioperative hypoxia, atelectasis, and postextubation croup are among the complications of anesthesia that are reported after the child with respiratory infection has surgery, particularly involving intubation. In the past, most clinicians recommended postponement of an elective procedure until the child had been free of symptoms for 1 week. Although there is no consensus on indications for canceling an elective procedure without endotracheal intubation, literature suggests that signs and symptoms of lower tract involvement such as fever of 38° C (100.4° F) or higher, lethargy, productive cough, wheezing, or tachypnea, in addition to a history of asthma, are more commonly associated with anesthesia-related morbidity. Similarly, if a bacterial infection is suspected, patients should be placed on antibiotic therapy and their procedure postponed for at least 4 weeks.35 Children with airway anomalies as part of a genetic syndrome should be approached with special caution (Table 5-1). Children with a history of prolonged endotracheal intubation may have subglottic stenosis and thus may be prone to airway obstruction. In addition, extremely obese children (body mass index higher than 40) may have airway problems related to excessive neck tissue.6,7

image TABLE 5-1

Congenital Conditions and Associated Clinical Features Pertaining to Airway

Pierre Robin sequence Micrognathia, macroglossia, glossoptosis, cleft lip and palate
Treacher Collins syndrome (mandibulofacial dysostosis) Auricular and ocular defects, zygomatic and mandibular hypoplasia or aplasia, microstomia, choanal atresia, palatopharyngeal incompetence, cleft palate
Crouzon syndrome Craniofacial synostosis, towering skull with proptosis, maxillary hypoplasia, beaked nose, high arched palate and malocclusion, cleft lip and/or palate, cervical vertebral fusions
Apert syndrome (acrocephalosyndactyly) Craniofacial synostosis, maxillary hypoplasia, prognathism, cleft palate, tracheobronchial cartilaginous anomalies, cervical vertebral fusions
Goldenhar syndrome (hemifacial microsomia) Auricular and ocular defects, zygomatic and mandibular hypoplasia, occipitalization of atlas, cleft lip and/or palate, velopharyngeal insufficiency and narrowed pharyngeal airway, cervical vertebral fusions
Down syndrome (trisomy 21) Narrow nasopharynx, large tonsils and adenoids, macroglossia, poorly developed or absent bridge of the nose, small subglottic area, microcephaly, cervical spine abnormalities, atlantoaxial subluxation, broad short neck, obesity
Klippel-Feil syndrome Congenital fusion of a variable number of cervical vertebrae, restriction of neck movement, cleft palate
Beckwith-Wiedemann syndrome (infantile gigantism) Macroglossia, predisposition for development of various neoplasms involving the head and neck
Cherubism (familial fibrous dysplasia) Tumerous lesions in the mandible and maxilla with intraoral masses, limited jaw closure and tongue displacement
Cretinism (congenital hypothyroidism) Macroglossia, compression of the trachea, deviation of larynx/trachea, laryngeal nerve palsies, paradoxical vocal cord motion
Cri du chat syndrome (deletion 5p syndrome) Microcephaly, micrognathia, laryngeomalacia, stridor, cleft lip and/or palate, short neck, hemivertebrae
Von Recklinghausen disease (neurofibromatosis) Tumors may occur in the larynx and right ventricle outflow tract, cervical spine abnormality, tongue lesions and macroglossia
Hurler syndrome (mucopolysaccharidosis I) Gargoyle facies, enlarged tongue, small mouth, profuse and thick secretions, upper airway obstruction due to infiltration of lymphoid tissue, abnormal tracheobronchia cartilages, stiff joints, kyphoscoliosis
Hunter syndrome (mucopolysaccharidosis II) Similar but less severe than those seen with Hurler syndrome
Pompe disease (glycogen storage disease II) Macroglossia, muscle deposits, respiratory muscle weakness
Prader-Willi syndrome Severe obesity, hypotonia
Osteogenesis imperfecta Long bone and spine deformities, short neck, joint hyperextensibility, hypoplastic maxilla, occipitalization of upper cervical vertebrae
Moebius syndrome (congenital facial diplegia) Hypoplastia of tongue and mandible, upper midfacial protrusion, high or cleft palate, microstomia, hypotonia creates swallowing difficulty, lack of facial expression, drooling, aspiration risk
Saethre-Chotzen syndrome Craniosynostosis, facial asymmetry, maxillary hypoplasia, narrow highly-arched palate, cleft palate, cervical vertebral fusions
Rubenstein-Taybi syndrome Facial deformation, highly arched palate, micrognathia, bifid uvula, palatal clefting, macroglossia, joint hyperflexibility, high potential for collapse of laryngeal walls
de Lange syndrome (Brachmann–de Lange syndrome) Severe growth deficiency, recurrent respiratory infections, depressed nasal bridge, highly arched palate, short muscular neck, micrognathia, cleft palate, prone to regurgitation and aspiration

From Waage NS, Baker S, Sedano HO: Pediatric conditions associated with compromi/>

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Jan 14, 2015 | Posted by in Pedodontics | Comments Off on 5: Topics in Pediatric Physiology
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