Determining Minimum Number of Attempts to Achieve Repeatability of Sniff Nasal Inspiratory Pressure Measures

Background:

The measurement of respiratory muscle strength is assessed using the maximal inspiratory pressure (MIP), the maximal expiratory pressure (MEP), and sniff nasal inspiratory pressure (SNIP). Presently, no guidelines specify the minimum number of SNIP attempts needed to achieve repeatability of this measure. Thus, the purpose of this study was to determine the minimum numbers of attempts of SNIP measures to achieve repeatability.

Methods:

This was a secondary analysis of data from a cross-sectional study of 85 subjects free of acute cardiopulmonary disease who were admitted to general medical and surgical floors of an acute care hospital. Up to 10 SNIP attempts using the MicroRPM were made by each subject to achieve acceptable and repeatable results. Demographic information and the number of attempts it took to achieve the highest SNIP and repeatable SNIP measures within 10% were recorded. Frequency and median values of attempts were computed.

Results:

Of the 70 (82%) subjects who achieved repeatable SNIP values, slightly more were female (57.1%) and from minority backgrounds: African American (48.6%), Hispanic (18.6%). The mean (SD) age was 51.1 y (15.9) with a range of 19-86. The mean peak SNIP value was 61.8 cm H₂O (28) with a range of 3-129. The median (IQR) number of attempts to achieve the highest SNIP value was 6 (4-8) and the earliest median repeatability attempt was a 7 (6-8).

Conclusions:

It appears that many hospitalized general medical and surgical patients can achieve repeatable SNIP maneuvers. A total of 8 attempts may be needed to allow most subjects to achieve their highest value. Publishing a standard specifying the minimum number of SNIP attempts could improve the precision of SNIP measurements.

Number of Attempts Needed to Achieve Highest SNIP Value and SNIP Repeatability (n = 70)