**9. PH in Cystic Fibrosis (CF)**

PH prevalence in CF population remains uncertain with figures as high as 21-59%. A retro‐ spective study of 179 pre-transplant CF patients revealed that 38.5% had PH with a RHC mean PAP of ≥ 25 mmHg [98]. In a recent series of 57 CF patients with advanced lung disease considered for lung transplant, 36 (63.2%) had PH [99]. Patients with PH were significantly more hypoxaemic than those without PH. A small number of patients (4) had more marked PH with mean PAP ≥40 mmHg [99].

PH develops as a consequence of alveolar hypoxemia and progressive destruction of the lung parenchyma and pulmonary vascular bed. However, other mechanisms may also be involved. An early study of the prevalence and impact of PH in adult patients with CF reported PH in 7 of 17 patients (41%) with stable but severe lung disease. PH correlated with declining FEV1, diurnal and nocturnal oxygen saturation [4]. However, Doppler echocardiography, although used routinely as an initial screening test to estimate PAP, may frequently be inaccurate and some studies report poor correlation with right heart catheter measures [99]. The clinical impact of PH in most CF patients' management is unclear, although a trend towards worsening mortality has been observed in some small studies.

No properly conducted studies of PH management in CF have been reported.
