Cardiopulmonary Function Changes In Patients With Ankylosing Spondylitis Kyphosis After Pedicle Subtraction Osteotomy

Objective:(1) To evaluate the preoperative cardiopulmonary function in patients with ankylosing spondylitis (AS) kyphosis before the pedicle subtraction osteotomy (PSO); (2) To follow the postoperative cardiopulmonary function in patients with AS kyphosis after the PSO; (3) To analyze the postoperative changes and the possible correlation.Methods:(1) To collect the general data, full-length spine x-ray films in natural standing position, pulmonary function tests (PFT), breath-holding time (BHT), echocardiographic measurements, resting heart rate (RHR), and active capacity score (ACS) in 36 AS patients before the PSO. (2) To follow the PFT, BHT, RHR, ACS, full-length spine x-ray films in natural standing position and echocardiographic measurements at 1 year postoperatively. (3) The statistical analysis was conducted between the pre- and postoperative cardiopulmonary parameters. Furthermore, to analyze the possible correlation in postoperative changes.Results:(1) 14 AS patients had normal left ventricular diastolic function before operation while there were 25 patients at 1-year follow-up. The clinical improvement rate was 72.2%. The preoperative RHR was 85.9 ± 12.5 beats per minute, whereas it was reduced to 71.8 ± 9.7 beats per minute at 1-year follow-up. The E/A ratio was increased from 1.02±0.36 preoperatively to 1.24 ± 0.27 at 1-year follow-up. (2) 3 AS patients had normal pulmonary function test before operation while there were 21 patients at 1-year follow-up. The clinical improvement rate was 79.3%. The BHT before surgery was 31.8 ± 9.8 s while the postoperative BHT was increased to 42.5 ± 9.3 s. The percent predicted vital capacity (PredVC%) and percent predicted forced vital capacity(PredFVC%) were increased to 79.6 ± 7.2% and 80.6 ± 6.4%. (3) The ACS was improved from 47.4 ± 18.2 points preoperatively to 78.3 ± 12.6 points at 1-year follow-up. (4) The improved BHT, PredVC% and PredFVC% had a positive correlation with the correction of GK (r=0.5428,0.5864 and 0.8143, respectively).Conclusion:The postoperative cardiopulmonary function in patients with AS kyphosis was significantly improved at 1-year follow-up. And the improved pulmonary function had a positive correlation with the kyphosis correction.