Comparison of exhaled and nasal nitric oxide and exhaled carbon monoxide levels in bronchiectatic patients with and without primary ciliary dyskinesia
Primary ciliary dyskinesia (PCD) is associated with chronic airway inflammation resulting in bronchiectasis. The levels of exhaled nitric oxide (eNO), carbon monoxide (eCO) and nasal NO (nNO) from bronchiectatic patients with PCD (n=14) were compared with those from patients with non-PCD bronchiectasis without (n=31) and with cystic fibrosis (CF) (n=20) and from normal subjects (n=37) to assess the clinical usefulness of these measurements in discriminating between PCD and other causes of bronchiectasis. Exhaled NO levels were lower in patients with PCD than in patients with non-PCD non-CF bronchiectasis or healthy subjects (median (range) 2.1 (1.3-3.5) ppb v 8.7 (4.5-26.0) ppb, p<0.001; 6.7 (2.6-11.9) ppb, p<0.001, respectively) but not lower than bronchiectatic patients with CF (3.0 (1.5-7.5) ppb, p>0.05). Nasal levels of nNO were significantly lower in PCD patients than in any other subjects (PCD: 54.5 (5.0-269) ppb, non-PCD bronchiectasis without CF: 680 (310-1000) ppb, non-PCD bronchiectasis with CF: 343 (30-997) ppb, control: 663 (322-1343) ppb). In contrast, eCO levels were higher in all patient groups than in control subjects (PCD: 4.5 (3.0-24.0) ppm, p<0.01, other bronchiectasis without CF: 5.0 (3.0-15.0) ppm, p<0.001; CF: 5.3 (2.0-23.0) ppm, p<0.001 v 3.0 (0.5-5.0) ppm). Low values in both eNO and nNO readings (<2.4 ppb and <187 ppb, respectively) identified PCD patients from other bronchiectatic patients with a specificity of 98% and a positive predictive value of 92%. The simultaneous measurement of eNO and nNO is a useful screening tool for PCD.