Pulmonary function test (PFT) abnormalities of primary pulmonary hypertension (PPH) include mild restrictive defects, reduced carbon monoxide diffusing capacity, and recently reported, small airway disease (SAD). We studied the relationship between small airways disease , airways responsiveness and its association with PHTN.
Records of all patients with PHTN [primary and those with collagen vascular disorders ] were reviewed. Air trapping was defined as RV/TLC > 30%, and SAD was diagnosed when forced expiratory flow between 25% to 75% of the vital capacity [FEF 25–75%] was < 65% predicted value. Airways responsiveness was defined as an increase in FEV1> 15% or FEF 25 –75% > 25% post inhaled Albuterol. Association between sex and FEF 25-75% (<65 or ≥65% of predicted) and RV/TLC(≤30%or >30%) was examined using the chi-square test. Comparison of age and DLCO% by FEF 25 –75% group (<65 %or ≥65% ) and RV/TLC(≤30%, or >30%) was made using the Mann-Whitney test.
60 patients were retrospectively studied [Females (n=44), Males (n=16)]. RV/TLC was reported in 53/60 [< 30 in 8 vs, > 30 in 45], but there was no statistical difference between age , sex and DLCO in these groups.The FEF 25-75% was available for 60 patients . SAD was observed in 33 [55%] . Airways responsiveness occurred in 12/33 patients. The patients with FEF 25-75% < 65% predicted were older [ 59.5 vs. 49.4 years ; p <0.02] and had lower DLCO [43.5% vs. 55.7% ;P< 0.01].
SAD is common in patients with PPH and correlates with impairment in DLCO. A significant proportion of these patients had bronchial hyperreactivity. High RV/TLC, an indicator of premature airway closure, may be present in some of these patients .
Clinician’s awareness of potential presence of bronchial reactivity and institution of appropriate therapy may impact on a patients well being. Measurement of expiratory flow rates along with bronchodilator testing is recommended when evaluating patients with PHTN.
A. Kyprianou, None.