Abstract
BACKGROUND: Nasal tracheal aspiration (NTA) is a frequently used diagnostic method to assess of infections in the lower airways. However, the validity of the method has not previously been compared to bronchoalveolar lavage (BAL) in non-intubated children with a lung disease. We hypothesised that NTA performed by health professionals using the nares vocal cord distance to be placed at the entrance of the trachea, will result in same finding of bacteria in the lower airways as the gold standard of BAL. METHODS: In a prospective study, 173 paired samples of NTA and BAL were obtained between June 2016 to August 2018. Samples were collected from all patients undergoing bronchoscopy with spontaneous breathing during general anaesthesia. This study compares the microbiological results from the cultures obtained by investigating complete concordance i.e. identical pathogenic bacteria and coherence i.e. absence or presence of pathogenic bacteria growth between NTA and BAL. RESULTS: Samples were collected in 164 patients, 158 children between 21 days and 18 years of age and six young adults still treated at the paediatric department. The overall similarity (complete agreement) was found in 49% [41-56], sensitivity was 35% [27-45], specificity was 66% [55-76], positive predictive value was 36% [27-46] and negative predictive value was 64% [54-64] concerning complete pathogenic bacteria concordance. If we only considered coherence growth of pathogenic bacteria, similarity was 71% [63-79], sensitivity was 74% [64-81], specificity was 66% [55-76], positive predictive value was 75% [65-82] and negative predictive value was 65% [54-75]. Patients with cystic fibrosis showed a similarity of 88% [73-95], a sensitivity of 92% [76-99], a specificity of 71% [36-95], a positive predictive value of 92% [76-99] and a negative predictive value of 71% [36-95] concerning coherence growth of pathogenic bacteria. CONCLUSION: The study indicates that NTA compared to BAL as the gold standard is not clinically useful to assess positive findings of specific bacteria in the lower airway tract. Statistically significantly increased sensitivity and positive predictive value were found in cystic fibrosis patients concerning coherence growth. The clinical usage of NTA remains important as negative findings are of clinical value. However, BAL continues to be preferred as a significantly superior diagnostic tool.