The Validity of Peak Nasal Inspiratory Flow as
a Screening Tool for Nasal Obstruction
Valin Rujanavej MD*, Kornkiat Snidvongs MD*,
Supinda Chusakul MD*, Songklot Aeumjaturapat MD*
Affiliation :
* Department of Otolaryngology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
Background : The peak nasal inspiratory flow (PNIF) is used as an outcome measure in post-treatment clinical and research
evaluation. It is simple and cost effective. The validity of the use as a screening tool has never been assessed.
Objective : To assess its validity and to define the cut-off point of determining the nasal obstruction
Material and Method: The nasal patency of 141 ambulatory subjects with or without sino-nasal diseases was measured by
the PNIF and active anterior rhinomanometry. Inclusion criteria was all subjects aged 18 to 75-years-old, sinonasal diseases/
symptoms(nasal congestion, nasal discharge, nasal polyp, deviated nasal septum, nasal tumor, inferior turbinate hypertrophy,
sinusitis, and allergic rhinitis), instant sensation of nasal obstruction, and nasal endoscopy finding were recorded. All
subjects signed written consent. Compared with the active anterior rhinomanometry as the gold standard, the sensitivity,
specificity, likelihood ratio, positive predictive value, and negative predictive value of the PNIF was analyzed. The cut-off
point of nasal obstruction was defined from the Receiver Operating Characteristic curve analysis. The agreement between
the PNIF and the stuffiness and between the PNIF and the presence of sino-nasal diseases were assessed by using Kappa.
Results : With the cut-off point of 90 L/min, the sensitivity of the peak nasal inspiratory flow was 0.87 (0.753-0.989). The
specificity was 0.52 (0.429-0.617). The negative predictive value was 0.93 (0.872-0.997). The positive predictive value
was 0.34 (0.237-0.446). The likelihood ratio was 1.81 (1.438-2.318). The mean of the PNIF in normal subjects was
97.11 31.15. The agreement between the PNIF and the instant sensation of nasal blockage was 0.14 (-0.024-0.321) and
the agreement between the PNIF and the sino-nasal diseases was 0.09 (-0.083-0.265).
Conclusion : The PNIF, regarding the cut-off point of 90 L/min, revealed good sensitivity and high negative predictive value
but it had low specificity and low positive predictive value. The nasal peak flow did not agree well with the subjects’ symptoms
of blockage and sino-nasal diseases.
Keywords : Peak nasal inspiratory flow, Active anterior rhinomanometry (AAR), Cut point, Sensitivity, Specificity, Receiver
operating characteristic curve analysis
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