Removing nasal valve obstruction in peak nasal inspiratory flow measurement Martyn L. Barnes, MBBS, and Brian J. Lipworth, MD Background: Peak nasal inspiratory flow (PNIF) measurements are used to evaluate nasal obstruction and as a surrogate for disease activity in allergic rhinitis and other nasal complaints. This measurement can give erroneous results when forced inspiration leads to nasal valve collapse. Objective: To determine the effects of 2 different nasal stents (Sinuscone and Nozovent) on valve collapse and repeatability of PNIF measurements. Methods: Repeated measurements of PNIF were obtained in 74 individuals with and without 2 different nasal stents: Sinuscone and Nozovent. Results: The mean (95% confidence interval) improvement in PNIF was 1.7 L/min (-2.4 to 5.8 L/min; P = .42) with Nozovents and 25.4 L/min (11.4 to 39.4 L/min; P = .001) with Sinuscones. The PNIF coefficient of variation for repeatability was 11.6% without stents, 16.0% using Nozovents, and 10.4% using Sinuscones. Conclusions: Sinuscones, but not Nozovents, significantly improved PNIF. Repeatability of PNIF measurements was worse with Nozovents and only marginally improved with Sinuscones. Ann Allergy Asthma Immunol. 2007;99:59–60. INTRODUCTION One of the greatest criticisms of peak nasal inspiratory flow (PNIF) measurement is the propensity for nasal valve col- lapse in forced inspiration, 1,2 leading to erroneously low mea- surements in individuals who may have very little nasal obstruction during normal tidal breathing. In an attempt to eliminate this error from the measurement, we made assess- ments of PNIF with and without 2 different nasal stents, quantifying effects on PNIF measurements and their repeat- ability in the same patients. We hypothesized that the use of nasal stents would not only reduce erroneous measurements and increase PNIF but also potentially improve the repeat- ability of the measure itself. METHODS We took 3 measurements with and without nasal stents for each of 2 different stent types (Nozovent [Pharmacure Healthcare AB, Va ¨stra Fro ¨lunda, Sweden] and Sinuscone [Sanostec, Beverly, Massachusetts]) (Fig 1). Participants were taken from study volunteers and patients in screening at the Asthma and Allergy Research Group, University of Dundee, including patients with intermittent or persistent allergic rhinitis. All the study participants gave informed consent, and each study was given a favorable opinion by the Tayside Committee on Medical Research Ethics, Dundee. Retrospective inclusion of data from screening volunteers was approved by the institution’s Caldicott Guardian and was, therefore, exempt from further ethical review. Means and 95% confidence intervals (CIs) were obtained for PNIF baseline values using 1-sample t tests. Improve- ments vs baseline for each stent were tested using paired- sample t tests. Coefficients of variation for within-subject repeatability were calculated for the 3 repeated measurements and represent test-retest repeatability across less than 5 min- utes. RESULTS Three repeated measurements with and without stents were obtained for 23 individuals using Sinuscones and 51 using Nozovents. Nozovent data were not available for 6 additional individuals who could not insert or keep the stents in position for the measurement. Sinuscones were more reliably adopted, and measurements were obtained for all participants. Mean PNIF without stents was 131 L/min (95% CI, 116 to 147 L/min) for the Sinuscone group and 121 L/min (95% CI, 104 Asthma and Allergy Research Group, Department of Medicine and Thera- peutics, Ninewells Hospital and Perth Royal Infirmary, University of Dundee, Dundee, Scotland. Authors have nothing to disclose. This research was funded by a departmental university grant. It received no financial support from the pharmaceutical and allied industries. Received for publication November 18, 2006. Received in revised form February 21, 2007. Accepted for publication March 2, 2007. Figure 1. Sinuscone (top) and Nozovent (bottom) nasal stents. VOLUME 99, JULY, 2007 59