North African reference equation for peak nasal inspiratory flow M DENGUEZLI BOUZGAROU 1,2 , H BEN SAAD 1,3 , A CHOUCHANE 1,2 , I BEN CHEIKH 1,2 , A ZBIDI 1,2,3 , J F DESSANGES 4 , Z TABKA 1,2,3 1 Laboratory of Physiology, Faculty of Medicine, Sousse ‘Ibn El Jazzar’, 2 Physiopathological Exploration of Chronic Cardiorespiratory and Metabolic Disease Research Unit and, 3 Physiology and Functional Exploration Service, Farhat Hached Hospital, Sousse, Tunisia, and 4 Respiratory Functional Exploration Service, Cochin Hospital, Paris, France Abstract Aim: To assess, in healthy North African subjects, the applicability and reliability of a previously published reference equation and normal values for peak nasal inspiratory flow, and to calculate a peak nasal inspiratory flow reference equation in this population. Subjects and methods: Anthropometric data were recorded in 212 volunteers (100 females and 112 males) aged 13– 27 years. Peak nasal inspiratory flow was measured several times. Univariate and multiple linear regression analyses were used to determine the reference equation. Results: The previously published reference equation and normal values did not reliably predict peak nasal inspiratory flow in the study population. In our subjects, the reference equation (r 2 = 30 per cent) for peak nasal inspiratory flow (l/min) was 1.4256 × height (m) + 33.0215 × gender (where 0 = female, 1 = male) + 1.4117 × age (years) - 136.6778. The lower limit of normal was calculated by subtracting from the peak nasal inspiratory flow reference value (84 l/min). Conclusion: This is the first published study to calculate a reference equation for peak nasal inspiratory flow in North African subjects. This equation enables objective evaluation of nasal airway patency in patients of North African origin. Key words: Nasal Cavity; Ethnic Groups; Nasal Obstruction Introduction Nasal obstruction is a common manifestation of rhini- tis. 1 This problem is difficult to quantify directly from clinical examination, so objective assessments such as rhinomanometry and acoustic rhinometry are commonly used. 1,2 However, these methods require complex, expensive equipment and highly trained operators. Subjective assessment of patient symptoms via questionnaires is also useful for diagnostic and research purposes. 1 However, subjective and objective measurements of nasal obstruction do not always corre- late. 1,3 Therefore, a simple, objective measurement of nasal airflow would be a very useful tool for assessing nasal patency. 4 The peak nasal inspiratory flow (PNIF) meter is a simple, cheap, noninvasive tool for this purpose. 3 –5 Furthermore, several authors have shown that PNIF is a reproducible measurement useful for the evaluation of nasal airway obstruction. 6,7 Starling-Schwanz et al. have demonstrated a good correlation between PNIF and the subjective sensation of nasal patency in young adults. 1 Interpretation of PNIF data relies upon comparison of measured values with predicted values available from published reference equations or normal value tables. However, to our knowledge, reference equations or normal values have only been established in two populations: Italian subjects aged 16– 84 years (PNIF reference equation, Ottaviano et al.), 8 and Greek chil- dren aged five to 18 years (normal PNIF values, Papachristou et al.). 9 However, neither of these studies provided prospective verification for their study populations, nor proposed a method of interpret- ing the measured PNIF (e.g. using a lower limit of normal, or a fixed percentage below which PNIF values would be considered abnormal). The need for reference equations specific to North African populations has been demonstrated for spirometry, 10–15 6-minute walk distance 16,17 and fat- free mass data. 18 The applicability and reliability of Accepted for publication 27 September 2010 The Journal of Laryngology & Otology, 1 of 8. MAIN ARTICLE © JLO (1984) Limited, 2011 doi:10.1017/S0022215111000181