Diagnostic accuracy and distress associated with oropharyngeal suction in cystic fibrosis

Background: Early detection of bacterial pathogens in the lower airway is an important part of managing CF. This study aimed to assess the diagnostic accuracy of oropharyngeal suction (OPS) samples in obtaining airway bacterial cultures in young children with cystic fibrosis (CF), and the level of child distress caused by obtaining OPS samples. Methods: Young children with CF undergoing broncho-alveolar lavage (BAL) as part of concurrent research or routine annual surveillance were studied. OPS was performed by stimulating a cough and suctioning the back of the oropharynx in the awake child to replicate clinical practice. BAL of the right upper, middle and lingula lobes was then performed. Samples were sent for standard bacterial culture. The child's distress during OPS was rated using the Groningen Distress Scale (1 = calm, 2 = timid/nervous, 3 = serious distress but still under control, 4 = serious distress with loss of control, 5 = panic). Results: There were 65 paired samples obtained from 39 children (21 boys, mean age on day of first sampling was 34.1 months, SD 19.1 months). For Pseudomonas aeruginosa, specificity, sensitivity, NPV and PPV with 95% CI were 98% (87–99), 75% (20–96), 98% (91–98) and 60% (15–93%) respectively. In all age groups combined, median level of distress was 3 (IQR 2–4), with distress highest in 2 and 3 year olds, with a median of 4 (IQR 3–4). Conclusion: OPS has diagnostic utility in determining the absence of organisms in the lower airway, with specificity for P.aeruginosa detection of 98%. However, a positive OPS result is not necessarily a good indicator of lower airway infection. Distress levels were high during OPS, mostly in 2 and 3 year olds.