How Is Pulmonary Function and Exercise Tolerance Affected in Patients With AIS Who Have Undergone Spinal Fusion?

Abstract

Prospectively enrolled AIS patients who underwent spinal fusion, with 2 year follow-up. To evaluate the cardiovascular fitness and activity level in patients with AIS pre- and post-spinal fusion and to determine if initial curve magnitude or pulmonary function is predictive of exercise capacity. Researchers have tried to link pulmonary function testing (PFT) to exercise capacity; the results are mixed. Some report no improvement in PFTs or aerobic activity after surgical correction, and PFT measures were not predictive of exercise capacity. Conflicting results have shown Vo_2max results to fall within normal range in AIS patients while PFTs show minimal impairment. AIS patients underwent PFT and oxygen consumption (VO₂) testing during a submaximal graded exercise test (GXT) pre- and post-spinal fusion. Vo_2max was predicted in those patients who completed the test to 85% of maximal heart rate. Pre- to postoperative changes were assessed and then compared to age-matched control subjects. Correlations between Vo_2max and curve severity, pulmonary function, and activity level were assessed. Thirty-seven patients participated. Vo_2max was predicted in 23 patients pre- and postoperation. There was a significant reduction in Vo_2max postfusion (39.5 ± 6.5 mL/kg/min vs 42.1 ± 8.1 mL/kg/min, p = .033); however, compared with controls (40.5 ± 6.5 mL/kg/min), all data were within the normal range (p > .05). AIS patients reporting high activity had significantly greater Vo_2max than those reporting low activity both pre and postoperatively, but this difference only met statistical significance preop (p < .05). Curve magnitude and PFT measures were not found to correlate with Vo_2max (p > .05). Vo_2max in patients with AIS is within normal range both pre- and postfusion. Pulmonary limitations are accommodated for with a slightly increased breathing rate and a slightly reduced overall workload. Activity level rather than curve severity affects Vo_2max outcomes following fusion in AIS.