Introduction and Objectives WHO Functional class (FC) is an important tool in the management of patients with pulmonary arterial hypertension. There is an increasing awareness of pulmonary hypertension (PH) as a complication of Sickle cell disease (SCD). We wished to evaluate functional class and gas transfer (diffusion capacity DLCOc, KCOc) in patients with SCD (HbSS) with and without PH based on trans thoracic echocardiogram.
Methods 32 patients were reviewed and their functional class was determined. Trans thoracic echocardiograms were reviewed in these patients for evidence of PH (defined as a tricuspid regurgitation jet velocity TRV ≥ 2. 5 m/s). Haematological and lung function data were also reviewed. Only patients in steady state and without a crisis in the preceding 2 weeks were included.
Results Of patients with PH 36% (5/14) were FC ≥3 compared to 6% (1/18) without PH. There was a significant difference in functional class in patients with and without PH on echocardiogram (p<0.05). There was a significant correlation between TRV and WHO functional class (p=0.002, r= 0.54). The correlation between TRV and functional class remained significant after correction for haemoglobin. Mean haemoglobin was 8.3±1.3 g/dl in those with PH and 10.1±1.4 g/dl in those without PH (p=0.001). Neither PH nor FC was associated with parenchymal abnormalities visible on CT and/or chest radiograph. PH was also associated with a lower diffusion capacity (DLCOc mmol/min/kPa: 3.60±0.79 vs 7.60±2.66, p=0.034) and a lower diffusion capacity corrected for alveolar volume (KCOc mmol/min/kPa/l: 1.04±0.31 vs 1.96±0.3, p=0.034). TRV was significantly correlated with DLCOc only (p=0.036 r= −0.79).
Conclusion Although patients with Sickle cell disease may have a number of reasons to account for their breathlessness, functional class and measurements of gas transfer may be useful markers in screening patients for pulmonary hypertension regardless of low steady state anaemia.