CHAPTER 58: Restrictive Disease of the Respiratory System

KEY POINTS

• Scoliotic curves greater than 100° may cause dyspnea; curves greater than 120° are associated with alveolar hypoventilation and cor pulmonale.

• Biphasic positive airway pressure may be effective in patients with acute hypercapnic respiratory failure.

• Low tidal volumes and high respiratory rates likely minimize the risk of barotrauma during mechanical ventilation; however, gradual institution of anti-atelectasis measures may improve gas exchange and static compliance.

• Nocturnal hypoxemia is common and may contribute to cardiovascular deterioration; routine polysomnography is recommended.

• Strategies for management of patients with chronic ventilatory failure include daytime intermittent positive pressure ventilation, nocturnal noninvasive ventilation, and ventilation through tracheostomy.

• Acute deterioration in respiratory status can occur from disease progression, upper and lower respiratory tract infections, congestive heart failure, failure to clear secretions, atelectasis, aspiration, and pulmonary embolism.

• Most patients with chest wall deformity survive their first episode of acute respiratory failure.

• Patients with idiopathic pulmonary fibrosis admitted to the ICU with acute respiratory failure have an extremely poor prognosis.

• If mechanical ventilation is deemed appropriate, the use of low tidal volumes and high respiratory rates during mechanical ventilation likely minimize ventilator-induced lung injury.

• Idiopathic pulmonary fibrosis is typically refractory to pharmacotherapy.

• Lung transplantation is a viable option in selected patients with end-stage fibrosis.

Thoracic cage deformity and pulmonary fibrosis both result in a restrictive limitation to breathing. Although relatively rare in the context of pulmonary intensive care, these disorders present unique challenges that complicate ICU management. In this chapter, we describe the pathophysiologic derangements in cardiopulmonary function associated with these disorders and how they affect management during acute illness. A primary goal of this chapter is to offer a strategy for cardiovascular management and mechanical ventilation that minimizes the risk of ventilator-induced complications and maximizes the chance for early, successful extubation. Many of these recommendations are grounded more on general precepts than on disease/disorder-specific evidence.

PATIENTS WITH THORACIC CAGE DEFORMITY

Although a number of disorders can deform and restrict the movement of the respiratory system (Table 58-1), kyphoscoliosis (KS) is the prototypical cause of severe thoracic deformity. Kyphoscoliosis is the combination of kyphosis (posterior deformity of the spine) and scoliosis (lateral deformity of the spine). It is far more common than isolated cases of kyphosis or scoliosis, placing over 200,000 people in the United States at risk of developing respiratory failure.¹ Most cases are idiopathic and begin in childhood.² Other cases result from congenital defects, connective tissue disease, poliomyelitis, thoracoplasty, syringomyelia, vertebral and spinal cord tumors, and tuberculosis.

The pathophysiologic consequences of KS correlate with the degree of spinal curvature, but there is considerable variability.^1-3 Patients with severe deformity can lead ...