PULMONARY-FUNCTION AFTER SPINAL SURGERY FOR IDIOPATHIC SCOLIOSIS

Respiratory function was assessed in 20 patients with idiopathic scoliosis undergoing spinal surgery (median age, 15 years; range, 11-34 years; median preoperative vital capacity, 67%; range, 28-109% predicted). Ten patients underwent anterior spinal surgery through a thoracotomy incision, seven of whom had posterior spinal surgery as a second-stage procedure. The other ten had posterior spinal surgery as their initial operation. Postoperatively, three patients had clinical evidence of respiratory complications. Daytime oxygen saturation was reduced throughout the first postoperative week, with no significant difference between anterior and posterior spinal surgery. Hypercapnia was unusual and generally mild. Vital capacity was reduced significantly 1 week after both anterior and posterior spinal surgery (P < 0.05). The median vital capacity 1 week after anterior spinal surgery was 45% of preoperative values compared with 78% after posterior surgery (P < 0.05). Inspiratory muscle strength, as assessed by sniff mouth pressure, was 56% of preoperative values 1 week after anterior spinal surgery (P < 0.05) and 85% after posterior spinal surgery (not significant). Vital capacity, but not sniff mouth pressure, remained significantly reduced 6 weeks after surgery. Oxygen saturation should be monitored noninvasively during the first week after both anterior and posterior spinal surgery even in patients at low risk of developing respiratory complications.