Abstract

Background: Adults and children with sickle cell disease (SCD) often have a restrictive pattern of pulmonary function and decreased DLCO. Echocardiography-determined tricuspid regurgitation jet velocity (TRV) ≥2.5 m/s occurs in about 30% of adults with SCD and is associated with increased mortality. Its prevalence and significance in children has not been established. We prospectively evaluated pulmonary function tests and their relationship to TRV in a multicenter study of children with SCD.

Methods: Patients with SCD (Hb SS, SC, Sb thalassemia or other major sickling phenotypes) aged 7 to 20 years were evaluated clinically and with spirometry, plethysmography, diffusing capacity, and echocardiography under basal circumstances. Controls were matched by ethnicity, sex and age to every sixth patient with SCD studied.

Results: Pulmonary function testing was performed in 115 of 267 children enrolled in the study as of August 2007 (93 had SCD and 22 were controls). TRV was measurable in 71 patients and 18 controls who had pulmonary function tests performed. FEV1 and FVC were significantly lower in children with SCD compared to controls and TRV was significantly higher, but FV1/FVC and TLC were not different. Among children with SCD, a higher TRV was associated with lower values for FEV1, FVC FEV1/FVC and TLC but not DLCO.

Conclusions: Similar to adults, pediatric patients with SCD had lower FEV1 and FVC than controls but almost identical FEV1/FVC suggesting restrictive lung dysfunction. In contrast to adults, DLCO was not lower among pediatric SCD patients than controls. Lower FEV1/FVC, a marker of obstructive lung dysfunction, correlated with higher TRV as did lower FVC and TLC, markers of restrictive lung dysfunction.

Table I.

Summary of pulmonary function tests. Results in mean (SD) unless otherwise indicated

SCD (n = 71)Control (n = 18)P
*N = 52 **N = 9 ***n = 59 ****n = 13 
Age (years) 13 (4) 12 (4) 0.2 
Females in no. and % 30 (42%) 13 (72%) 0.023 
FEV1 (% predicted) 89 (16) 99 (16) 0.025 
FVC (% predicted) 93 (16) 104 (17) 0.018 
FEV1/FVC (%) 84 (7) 84 (6) 0.9 
TLC (% predicted) 89 (15)* 98 (18)** 0.2 
Residual volume (% predicted) 105 (39)* 117 (46)** 0.5 
DLCO adjusted for hemoglobin (% predicted) 99 (20)*** 88 (12)**** 0.019 
TR velocity (m/sec) 2.3 (0.3) 2.1 (0.3) 0.021 
SCD (n = 71)Control (n = 18)P
*N = 52 **N = 9 ***n = 59 ****n = 13 
Age (years) 13 (4) 12 (4) 0.2 
Females in no. and % 30 (42%) 13 (72%) 0.023 
FEV1 (% predicted) 89 (16) 99 (16) 0.025 
FVC (% predicted) 93 (16) 104 (17) 0.018 
FEV1/FVC (%) 84 (7) 84 (6) 0.9 
TLC (% predicted) 89 (15)* 98 (18)** 0.2 
Residual volume (% predicted) 105 (39)* 117 (46)** 0.5 
DLCO adjusted for hemoglobin (% predicted) 99 (20)*** 88 (12)**** 0.019 
TR velocity (m/sec) 2.3 (0.3) 2.1 (0.3) 0.021 
Table II.

Spearman Correlation of Pulmonary Function Tests with TRV in SCD Patients

NRP value
FEV1 (% predicted) 71 −0.299 0.011 
FVC (% predicted) 71 −0.257 0.030 
FEV1/FVC (%) 71 −0.257 0.030 
TLC (% predicted) 52 −0.263 0.060 
DLCO adj. for hemoglobin (% predicted) 59 −0.098 0.2 
NRP value
FEV1 (% predicted) 71 −0.299 0.011 
FVC (% predicted) 71 −0.257 0.030 
FEV1/FVC (%) 71 −0.257 0.030 
TLC (% predicted) 52 −0.263 0.060 
DLCO adj. for hemoglobin (% predicted) 59 −0.098 0.2 

Author notes

Disclosure: No relevant conflicts of interest to declare.