Abstract
This chapter provides a brief overview for the patient with thoracic insufficiency syndrome. The author discusses the pathophysiology of thoracic insufficiency syndrome and the Vertical Expandable Prosthetic Titanium Rib insertion procedure. The complex perioperative consideration in these children are presented from the anesthesia perspective.
A two-year-old boy is scheduled for placement of a vertical expandable prosthetic titanium rib (VEPTR) system for progressive thoracic insufficiency syndrome in the setting of unilateral thoracic hypoplasia. His past medical history includes a staged repair of a tracheoesophageal fistula and a protracted hospital stay in the newborn period, including a tracheostomy that remained in place until about 1 year of age. His current medications include metoprolol and preoperative vancomycin. His current vital signs are: blood pressure 86/52 mmHg; heart rate 110/min and regular; respiratory rate 37/min; temperature 36.5ºC; SpO2 93% on room air. Physical exam reveals an alert and anxious child with normal facial structures. He has a tracheostomy scar. He is not flaring, but he is using his left-sided accessory muscles of breathing. He has right-sided neck torticollis but his airway exam is otherwise unremarkable.
Chest radiograph demonstrates scoliosis with a curve of 100 degrees in the thoracic spine and left sided lung volumes four times smaller than the right side (Figure 49.1).
What Is Thoracic Insufficiency Syndrome?
Thoracic insufficiency syndrome results from any condition that alters thoracic development and results in decreased lung growth. The normal thorax has two important functions: to maintain a constant and normal lung volume and to effortlessly change this volume. Lung volume depends on thoracic spine height and an equally broad and wide enough rib cage. Ventilation (lung volume exchange) depends on normal bilateral diaphragm excursion, rib orientation (recall the bucket handle mechanism) and functioning of the secondary muscles of respiration. The components of the normal thorax consist of the spine, sternum, ribs, secondary muscles of respiration, and diaphragm.
Lung development depends on normal thoracic growth, which entails a coordinated increase in thoracic spine height, and symmetrical enlargement of the rib cage that requires both rib growth and the correct orientation of the ribs. The thoracic spine lengthens by about 1.5 cm/year for the first five years of life, then slows down to about 0.5 cm/year until it experiences another growth spurt of 1.2 cm/year from 11–15 years of age. In the first two years of life, the rib cage is square shaped, the ribs are orientated horizontally and grow in length. Between two and 10 years of age it courses downward and forms an oval-shaped thoracic cross-section. There is a rapid increase in rib growth after the age of 10 years until the child reaches maturity; the final cross-section of the thorax is rectangle shaped.
The diagnosis of thoracic insufficiency is made when the patient has physiologic signs of respiratory impairment, a decrease in chest wall mobility, and worsening lung volumes on imaging. If obtained, pulmonary function tests demonstrate a restrictive pattern with a smaller than predicted vital capacity.
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