Anesthetic Considerations in Scoliosis

SCOLIOSIS

Pathophysiology

Scoliosis is lateral rotation and curvature of the ver-tebrae and a deformity of the rib cage. It can have many etiologies, including idiopathic, congenital, neuromuscular, and traumatic. Scoliosis can affect cardiac and respiratory function. Elevated pul-monary vascular resistance from chronic hypoxia causes pulmonary hypertension and right ventricu-lar hypertrophy. Respiratory abnormalities include reduced lung volumes and chest wall compliance. Pao₂ is reduced as a result of ventilation/perfusion mismatching, whereas an increased Paco₂ signals severe disease.

Anesthetic Considerations

Preoperative evaluation may include pulmonary function tests, arterial blood gases, and electrocar-diography. Corrective surgery is complicated by the prone position, significant blood loss, and the possibility of paraplegia. Spinal cord function can be assessed by neurophysiological monitoring (somatosensory and motor evoked potentials) or by awakening the patient intraoperatively to test lower limb muscle strength. Patients with severe respiratory disease often remain intubated postoperatively. Patients with scoliosis due to muscular dystrophy arepredisposed to malignant hyperthermia, cardiac arrhythmias, and untoward effects of succinylcho-line (hyperkalemia, myoglobinuria, and sustained muscular contractures).