Comparison between a national and a foreign manovacuometer for nasal inspiratory pressure measurement

Background: The measurement of nasal inspiratory pressure, known as the sniff test, was developed as a new test of inspiratory muscle strength, mainly used in neuromuscular conditions. The test is easy to be performed and noninvasive. Despite the clinical importance of assessment of nasal inspiratory pressure a national equipment is not available to assess it. Objectives: To compare a national with a foreign manovacuometer in assessing the nasal inspiratory pressure (sniff test) in healthy subjects. Methods: 18 subjects were evaluated (age 21.44 +/- 2.8 years, BMI 23.4 +/- 2.5 kg/m(2), FVC 102.1 +/- 10.3% pred, FEV1 98.4 +/- 1% pred). We performed two measures of nasal inspiratory pressure using two different manovacuometer: a national and a foreign. All subjects performed the tests at the same time of day, in different days being the order of the testes established randomly. It was used the paired t test, Pearson correlation and the Bland-Altman plots for statistical analysis considering a 5% significance level. Results: The averages observed for the two measures of nasal pressures were 125 +/- 42.4 cmH(2)O for the foreign equipment, and 131.7 +/- 28.7 cmH(2)O for the national equipment. The Pearson correlation showed significant correlation between the means with a coefficient of r=0.63. The t test showed no significant differences between both measurements (p>0,05). The BIAS +/- SD found in Bland-Altman plot analysis was 7 cmH(2)O with limits of agreement between -57.5 cmH(2)O and 71.5 cmH(2)O. Conclusion: The results suggest that the national electronic device is feasible and safe to the sniff test measurement in healthy subjects.