REFERENCE VALUES FOR SNIFF NASAL INSPIRATORY PRESSURE IN HEALTHY CHILDREN: A MULTICENTER STUDY
child, respiratory muscles, reference values.
Introduction: The sniff nasal inspiratory pressure (SNIP) is an easy to perform test that estimates esophageal pressure and predicts inspiratory muscle strength, being complementary to maximal inspiratory and expiratory pressure measurements (MIP and MEP, respectively). In Brazil, its reference values for children have not yet been proposed. Objective: To propose SNIP prediction equations for healthy Brazilian children and determine the reference values for this population. Methods: A multicenter (Natal, Recife e Belo Horizonte), cross-sectional observational study was carried out to evaluate healthy children 6 to 12 years of age incomplete, of both sexes. They were stratified into three subgroups (6-7, 8-9, 10-11 years) within each sex. All performed after anamnesis with sociodemographic and anthropometric evaluation (percentile), the spirometry test, followed by the measurement of respiratory muscle strengths, composed of MIP (Functional Residual Capacity (FRC) and Residual Volume (RV)), MEP and SNIP. Finally, two 6-minute walk tests (6MWT) were performed to assess functional exercise capacity. Statistical analysis: We used the Kolmogorov-Smirnov test for normality of the data, and the t test to test the intergroup relations and one-way ANOVA for intragroup analyzes. Linear regression analysis was used to obtain predictive equations for the independent variables that correlate with nasal inspiratory pressure. Results: A total of 135 children were evaluated in the Natal center, of which 118 were included in the study. Girls achieved slightly higher SNIP values in boys (91.3 ± 21.2 vs 89.4 ± 19.6), but without statistical significance. While the values of MIPFRC, MIPVR and MEP were significantly higher in males (p = 0.039, p = 0.009 and p = 0.025, respectively). In boys, the SNIP correlated positively with height (cm) (r = 0.254)., while in girls, with weight and percentile (r = 0.233, r = 0.276) respectively. Thus, the following equations were generated for the male and female, respectively: SNIP = 21,257 + 0,497 * heightcm; SNIP = 72.12% + 0.230 * weightkg + 0.167 * percentile. Conclusions: According to what was found from linear regression, the variables that influenced SNIP in girls were weight and percentile, and in boys only height, results found for healthy Brazilian children in the city of Natal.