Intra-rater reliability of measuring diaphragm thickness utilising ultrasound imaging by a non-sonographer practitioner

Abstract

BACKGROUND: As the primary muscle of ventilation, the diaphragm has a pivotal role in breathing, and in maintaining homeostasis for all other body systems. There have been several previous studies assessing reliability of measuring diaphragm muscle thickness using ultrasound imaging (USI) by qualified sonographers, however, no previous study has investigated reliability of measurement by a rehabilitation practitioner. Additionally, no evaluation has been done to determine a link between diaphragm thickness and breathing measures

AIMS: (1) To investigate the reliability of diaphragm thickness measurements utilising USI by a non-sonographer (‘novice operator’); and (2) To evaluate the correlation between diaphragm thickness measurements including contractility and dysfunctional breathing as measured by the Self Evaluated Breathing Questionnaire (SEBQ) and the Nijmegen Questionnaire (NQ)

METHODS: High-resolution, B-mode ultrasound was utilised to execute a standardized protocol for repeated thickness measurements of diaphragm muscle. A convenience sample of 25 participants (13 males, 12 females, mean ± SD age = 27 ±7.2 years, height 172.6 ± 9.3cm, body mass 79 ± 14.5 and a mean SEBQ and NQ score of 14.9 ± 11.2 and 13.3 ± 7.2, respectively) attended two sessions, separated by an interval of approximately 2 weeks. Intraoperator reliability was calculated for all thickness measurements obtained by the novice USI operator.

RESULTS: The novice operator demonstrated ‘very high’ intra-operator reliability for diaphragm muscle thickness measurements during all stages of breathing except for maximal inspiration on the right (all other ICCs >0.8). However it was apparent that diaphragm contractility may not be an adequate measure of diaphragm function as measured by the SEBQ and NQ.

CONCLUSION: Within this study, the novice operator demonstrated acceptable reliability for diaphragm muscle thickness measurements using USI. The novice operator demonstrated very high intra-operator reliability for diaphragm measurements during quiet exhalation on both sides and at the level of maximal inspiration on the left.