Normative Data of Pulmonary Function Tests and Measures

Normative Data of Pulmonary Function Tests and Measures of Chest Development: Is a T 1 -T 12 Height of 22 cm Adequate? June Smith, MPH Megan Kerstein James Gregory, MD Scott J. Luhmann, MD Department of Orthopaedic Surgery Washington University School of Medicine

Introduction • Shortening of the spine from T 1 -T 12 has deleterious effects on PFTs – Karol et al, JBJS 2008 • Mean age at surgery 3. 3 yrs; 59% of T spine fused • FEV 1 & FVC at 14. 6 yr f/u: 55 -58% predicted – Emans et al, SRS 2004 • Inverse relationship between %-predicted PFTs at f/u and either # levels fused or earlier age at fusion. • There has been suggestion a T 1 -T 12 height of 22 cm at skeletal maturity is adequate for pulmonary function

Study Purpose • To develop normative data on PFTs and radiographic measures of chest development in “normal” patients. • To determine if T 1 -T 12 height of 22 cm is adequate, based on normative PFT values, at skeletal maturity.

Methods • St. Louis Children’s Hospital Pulmonology database – All patients who underwent PFT testing – PFT values of greater than 90%, consist of patients with minimal to mild asthma – Exclusion: any chest wall or spine deformity • Cross-referenced to Radiology database to identify all identified patients who had a chest radiograph within 2 months of PFT testing.

Sample Chest Radiograph: 16 y/o Female presenting with shortness of breath with exercise

Methods • Initial query of Pulmonology database: 1797 PFT studies • After cross-referencing with Radiology database: – 149 patients with 149 data points – Mean age 12. 4 years (7. 1 to 18. 4 years)

Methods # Patients by Gender in Each Age Group 45 40 35 30 25 20 15 10 5 0 Under 10 years <10 yrs 10 -12 years 10 -11 yrs Females Mean age 8. 7 yrs 11. 1 yrs 12 -14 years 12 -13 yrs 14+ years >14 yrs Males 12. 8 yrs 15. 8 yrs

Methods • PFT data – Absolute FVC – %-predicted FVC – Absolute FEV 1 – %-predicted FEV 1 • Chest Radiographs – T 1 -T 12 length *Taken from the GSSG Measurement Guide – Coronal Chest Width (CCW) – Space Available for the Lung (SAL)

Results: Entire Cohort • Radiographic Measures (means) – T 1 -T 12: 25. 6 cm – CCW: 25. 5 cm – SAL: 19. 0 cm bilateral • PFTs (means) – Absolute FEV 1: 2. 69 l – %-predicted FEV 1: 106. 9% – Absolute FVC: 2. 97 l – Mean %-predicted FVC: 103. 9%

Results FVC and FEV values by Age 4. 50 4. 00 3. 50 Liters Female FVC Male FVC 3. 00 Female FEV 1 Male FEV 1 2. 50 2. 00 1. 50 Under 10 <10 yrs Mean age 8. 7 yrs 10 -12 years 12 -14 years 10 -11 yrs 12 -13 yrs 11. 1 yrs 12. 8 yrs 14+ years >14 yrs 15. 8 yrs

Results T 1 -T 12 LENGTH STRATIFIED BY AGE Female T 1 -T 12 Length Male T 1 -T 12 Length Female Height Male Height 200. 00 160. 77 T 1 -T 12 Length (cm) 29. 0 129. 00 149. 13 156. 82 144. 69 27. 0 129. 64 173. 53 162. 74 29. 70 28. 62 26. 87 140. 00 100. 00 80. 00 24. 22 60. 00 24. 26 23. 0 40. 00 21. 50 20. 00 21. 19 21. 0 Under 10 <10 yrs Mean age 160. 00 120. 00 26. 72 25. 0 180. 00 8. 7 yrs 0. 00 10 -12 years 12 -14 years 10 -11 yrs 12 -13 yrs 11. 1 yrs 12. 8 yrs 14+ years >14 yrs 15. 8 yrs h. EIGHT (CM) 31. 0

Results Female Coronal Chest Width Coronal chest width (cm) 30. 0 Male Coronal Chest Width 149. 13 129. 64 28. 0 Female Height 160. 77 156. 82 173. 53 Male Height 180. 00 162. 74 29. 98 27. 20 27. 52 26. 0 120. 00 100. 00 24. 98 24. 0 22. 0 160. 00 144. 69 129. 00 200. 00 25. 41 80. 00 23. 91 60. 00 22. 64 21. 98 40. 00 20. 0 Mean age Under 10 <10 yrs 8. 7 yrs 10 -12 years 10 -11 yrs 12 -14 years 12 -13 yrs 14+yrs years >14 11. 1 yrs 12. 8 yrs 15. 8 yrs 0. 00 h. EIGHT (CM) 32. 0 CORONAL CHEST WIDTH STRATIFIED BY AGE

Results Space Available Stratified by Age 29. 0 27. 0 25. 0 23. 0 22. 54 21. 44 21. 0 19. 97 19. 53 19. 0 18. 18 17. 77 17. 0 16. 01 15. 0 Mean age 15. 20 Under 10 <10 yrs 10 -12 years 10 -11 yrs 12 -14 years 12 -13 yrs 14+ years >14 yrs 8. 7 yrs 11. 1 yrs 12. 8 yrs 15. 8 yrs Female SAL Male SAL

Results • Subcohort: Patients with T 1 -T 12 height of 22 -24 cm – 21 patients (11 female, 10 male)

Results Mean FVC FEV 1 Age Height Weight FVC% FEV 1/FVC CCW T 1 -T 12 HT SAL L R 2. 17 l 1. 97 l 9. 68 136. 90 33. 98 103. 95 108. 24 91. 00 23. 33 22. 83 16. 16 16. 32 Std. Minimu Deviation m 0. 33 l 1. 67 l 0. 31 l 1. 50 l 1. 39 7. 58 7. 97 120. 00 6. 18 22. 40 12. 99 90. 00 14. 98 92. 00 2. 65 88. 00 1. 50 21. 08 0. 60 22. 11 1. 98 12. 11 1. 62 13. 06 Maximu m 2. 88 l 2. 83 l 11. 90 152. 00 46. 00 139. 00 155. 00 98. 00 26. 58 23. 99 18. 56

Results • Spirometric standards for healthy adult lifetime nonsmokers, by Gore et al, were utilized to assess the impact of T 1 -T 12 shortening on PFT values. • Input: – Mean absolute FEV 1 and FVC values for the subcohort – Mean height of 14+ females (163. 41 cm) and 14+ males (168. 7 cm)

Results • 15 year old females – FEV 1 %-predicted: – FVC %-predicted: 46% 44% • 15 y/o males – FEV 1 %-predicted: 43% – FVC %-predicted: 42%

Limitations • “Normals” had minimal to mild asthma • Does not take into consideration radial expansion of the chest during maturity CORONAL CHEST WIDTH STRATIFIED BY AGE Female Coronal Chest Width Male Coronal Chest Width 31. 0 29. 98 29. 0 27. 0 25. 0 23. 0 21. 0 24. 98 23. 91 27. 20 25. 56 27. 56 22. 64 21. 98 Under 10 10 -12 yrs years 10 -11 12 -14 12 -13 years yrs 14+ years

Conclusion • T 1 -T 12 height at skeletal maturity of 22 cm may not be enough to guarantee patients will have an asymptomatic pulmonary status in adulthood. • Though this analysis does not take into consideration radial expansion of the chest during maturity, the %-predicted FEV 1 and FVC values are concerning, and deserve further analysis. • Plea for collaboration to expand deepen this data.

Thank You