Should postoperative pulmonary function be a criterion that affects upper instrumented vertebra selection in adolescent idiopathic scoliosis surgery?

Pulmonary function in children and adolescents with untreated idiopathic scoliosis: a systematic review with meta-regression analysis

BACKGROUND CONTEXT

One of the controversies in untreated idiopathic scoliosis is the influence of curve size on respiratory function. Whereas scoliosis patients with curves over 90 to 100 degrees are agreed to be at risk for cardiorespiratory failure in later life, the impairment of curves below 90 degrees is generally considered mild. Although various studies showed that pulmonary function is affected in patients with scoliosis, quantification of the relation between curve size and pulmonary function is lacking.

PURPOSE

This systematic review with meta-regression analysis aims to characterize the relation between pulmonary function tests and scoliosis severity in children and adolescents with idiopathic scoliosis.

STUDY DESIGN

Systematic review with meta-regression analysis.

METHODS

Pubmed, Embase, Cochrane, and CINAHL were systematically searched until November 3, 2020, for original articles that reported (1) severity of scoliosis quantified in Cobb angle, and (2) pulmonary function tests in children and adolescents with untreated idiopathic scoliosis. Exclusion criteria were other types of scoliosis, non-original data, post-treatment data, and case reports. All study designs were included, and relevant study details and patient characteristics were extracted. The primary outcome was the effect of Cobb angle on pulmonary function as expressed by the slope coefficient of a linear meta-regression analysis.

RESULTS

A total of 126 studies, including 8,723 patients, were retrieved. Meta-regression analysis revealed a statistically significant inverse relation between thoracic Cobb angle and absolute and predicted forced vital capacity in 1 second, forced vital capacity, vital capacity, and total lung capacity. For these outcomes, the slope coefficients showed a decrease of 1% of the predicted pulmonary function per 2.6 to 4.5 degrees of scoliosis. A multivariable meta-regression analysis of potential confounders (age, year of publication, and kyphosis) hardly affected the majority of the outcomes.

CONCLUSION

This meta-regression analysis of summary data (means) from 126 studies showed an inverse relationship between the thoracic Cobb angle and pulmonary function. In contrast to previous conclusions, the decline in pulmonary function appears to be gradual over the full range of Cobb angles between <20 and >120 degrees. These findings strengthen the relevance of minimizing curve progression in children with idiopathic scoliosis.

Does pulmonary function improve after surgical correction of adult idiopathic scoliosis?

PURPOSE

The aim was to investigate pulmonary function after surgical correction of adult idiopathic scoliosis.

METHODS

This study included 146 adult scoliosis patients aged 20-50 years (main curve in thoracic spine). Respiratory function was assessed as predicted forced vital capacity (%FVC) and the ratio of forced expiratory volume in 1 s / FVC (%FEV₁) preoperatively and 2 years postoperatively and classified as a normal function (≥ 80%), mild impairment (≥ 65% and < 80%), and moderate impairment (< 65%).

RESULTS

Preoperative %FVC and %FEV₁ were 85.3% and 85.4%, which were 81.5% and 87.5% at 2 years post-surgery. The preoperative %FVC was mild and moderate in 39 (26.7%) and 12 patients (11.6%), respectively. The %FVC significantly improved (+ 6.2% ± 11.4%, P < 0.001) postoperatively for moderate severity but significantly decreased postoperatively (- 6.4% ± 9.4%, P < 0.001) for normal function. The preoperative %FEV₁ was mild and moderate in 27 (18.5%) and 0 patients, respectively. The %FEV1 significantly improved postoperatively (6.3% ± 5.3%, P < 0.001) for mild severity but did not significantly change for normal severity. Twenty-three (15.8%) and 41 (28.1%) patients showed improved ⊿%FVC and ⊿% FEV₁ > 5%. Logistic regression analysis showed that preoperative %FVC and %FEV₁ severities were independent factors affecting postoperative recovery of %FVC (OR 0.95) and %FEV₁ (OR 0.85).

CONCLUSION

Pulmonary function improved in patients with preoperative pulmonary impairment of < 65% in %FVC and < 80% in %FEV₁, and the real improvement was limited to patients with severe preoperative impairment.

Does Posterior Scoliosis Correction Improve Respiratory Function in Adolescent Idiopathic Scoliosis? A Systematic Review and Meta-analysis

STUDY DESIGN

A systematic review and meta-analysis.

OBJECTIVES

Pulmonary dysfunction is often advocated among the indications for surgical correction of adolescent idiopathic scoliosis (AIS). Previous studies have discussed the effect of scoliosis correction on respiratory function without reaching a definitive conclusion: Some showed that the respiratory function can improve after scoliosis surgery without defining the precise role of anterior, posterior, and combined approaches on this improvement; furthermore, the majority of these studies did not take normal growth into account. As a result, the role of surgery remains to be clarified. The object of the present study was to synthesize the current knowledge regarding changes in respiratory function after posterior corrective surgery for AIS.

METHODS

A comprehensive systematic search was performed to identify all relevant studies in the following electronic databases: MEDLINE, EMBASE, CINAHL (EBSCO). We focused on the studies (1) that discussed posterior fusion surgery for AIS without thoracoplasty, (2) that discussed comparisons of pre- and postoperative percent-predicted values of forced vital capacity (%FVC) or forced expiratory volume (%FEV), and (3) with minimum 2-year follow-up. Forest plots were depicted and Z value was calculated as a test for overall effect.

RESULTS

Ten studies (6 prospective and 4 retrospective studies) met our inclusion criteria. The overall effect showed that there was no significant difference in %FVC or %FEV between pre- and postoperative measurements (very low evidence).

CONCLUSIONS

Posterior correction surgery for mild to moderate AIS patients showed no significant improvement of postoperative respiratory function measured by relative, percent-predicted values at minimum 2-year follow-up.

Predicting massive transfusion in adolescent idiopathic scoliosis patients undergoing corrective surgery: Association of preoperative radiographic findings

Corrective surgery with a posterior approach for adolescent idiopathic scoliosis (AIS) is often accompanied by considerable bleeding. Massive transfusion after excessive hemorrhage is associated with complications such as hypothermia, coagulopathy, and acid-base imbalance. Therefore, prediction and prevention of massive transfusion are necessary to improve the clinical outcome of AIS patients. We aimed to identify the factors associated with massive transfusion in AIS patients undergoing corrective surgery. We also evaluated the clinical outcomes after massive transfusion.We included and analyzed AIS patients who underwent corrective surgery with a posterior approach from January 2008 to February 2015. We retrospectively reviewed the electronic medical records of 765 consecutive patients. We performed multivariable logistic regression analysis to assess the factors related to massive transfusion. Furthermore, we compared the effects of massive transfusion on clinical outcomes, including postoperative morbidity and hospital stay.Of 765 patients, 74 (9.7%) received massive transfusion. Body mass index (odds ratio [OR] 0.782, 95% confidence interval [CI] 0.691-0.885, P < .001) and the number of fused vertebrae (OR 1.322, 95% CI 1.027-1.703, P = .03) were associated with massive transfusion. In the comparison among the different Lenke curve types, Lenke type 4 showed the highest prevalence of massive transfusion. Patients in the massive transfusion group showed a higher incidence rate of postoperative morbidity and prolonged hospital stay.Massive transfusion was required in 9.7% of AIS patients who underwent corrective surgery with a posterior approach. A lower body mass index and higher number of fused vertebrae were associated with massive transfusion. Massive transfusion is related to poor clinical outcomes in AIS patients.

Effect of Surgical Approach on Pulmonary Function in Adolescent Idiopathic Scoliosis Patients: A Systemic Review and Meta-analysis

STUDY DESIGN

Systemic review and meta-analysis.

OBJECTIVE

To analyze the effect of spinal fusion and instrumentation for adolescent idiopathic scoliosis (AIS) on absolute pulmonary function test (PFTs).

SUMMARY OF BACKGROUND DATA

Pulmonary function is correlated with severity of deformity in AIS patients and studies that have analyzed the effect of spinal fusion and instrumentation on PFTs for AIS have reported inconsistent results. There is a need to analyze the effect of spinal fusion on PFTs with stratification by surgical approach.

METHODS

Our analysis included 22 studies. Cohen's d effect sizes were calculated for absolute PFT outcome measures with 95% confidence intervals (CI). Meta-analyses were performed at each postoperative time frame for six homogeneous surgical approaches: (i) combined anterior release and posterior fusion with instrumentation; (ii) combined video assisted anterior release and posterior fusion with instrumentation without thoracoplasty; (iii) posterior fusion with instrumentation without thoracoplasty; (iv) anterior fusion with instrumentation and without thoracoplasty; (v) video assisted anterior fusion with instrumentation without thoracoplasty; and (vi) any scoliosis surgery with additional thoracoplasty.

RESULTS

Anterior spinal fusion with instrumentation, any scoliosis surgery with concomitant thoracoplasty, or video-assisted anterior fusion with instrumentation for AIS had similar absolute PFTs at their 2 year postoperative follow up compared with their preoperative PFTs (effect sizes ranging from -0.2-0.2 with all CI crossing "0"). Posterior spinal fusion with instrumentation (with or without an anterior release) demonstrated small to moderate increases in PFTs 2 years postoperatively (effect sizes ranging from 0.35-0.65 with all CI not crossing "0").

CONCLUSION

Anterior fusion with instrumentation, regardless of the approach, and any scoliosis surgery with concomitant thoracoplasty do not lead to significant change in pulmonary functions 2 year after surgery. Posterior spinal fusion with instrumentation (with or without an anterior release) resulted in small to moderate increases in PFTs.

LEVEL OF EVIDENCE

N/A.

Three-dimensional computed tomography for assessing lung morphology in adolescent idiopathic scoliosis following posterior spinal fusion surgery

OBJECTIVE

To evaluate the changes in lung morphology in subjects with adolescent idiopathic scoliosis (AIS) following posterior spinal fusion surgery.

METHODS

From April 2009 to August 2013, 30 AIS patients (nine males and 21 females) were enrolled in this study. All scans were obtained with the patient in the supine position and the breath held in deep inspiration and performed both before and after surgery. Syngo software was used to manage the computed tomography scan imaging and to calculate the lung volume, lung height and pulmonary cross-sectional area in the apical vertebral plane.

RESULTS

Left lung, right lung and total lung volumes and convex to concave lung volume ratio did not change significantly after corrective surgery. There was a statistically significant improvement in left lung and right lung heights after posterior spinal fusion surgery. However, the pulmonary cross-sectional area in the apical vertebrae plane was smaller postoperatively than preoperatively.

CONCLUSIONS

This study showed that lung height in AIS patients increased significantly immediately postoperatively whereas lung volume did not change significantly. Thoracic symmetry was improved postoperatively in these patients.