Impact of respiration on abdominal pain thresholds in healthy subjects - A pilot study.

Objectives: Pressure algometry is a validated method for objectively quantifying pain sensitivity in musculoskeletal disorders, particularly useful for diagnosis and monitoring of treatment responses. However, its application to abdominal pain sensitivity remains insufficiently standardized, especially regarding the influence of physiological factors such as respiration. This study investigated the impact of respiratory phase (inhalation vs exhalation) on abdominal pressure pain thresholds (PT) to support the development of standardized assessment protocols.

Methods: Thirty-one healthy medical students were recruited for the study. Each participant underwent three assessments of the abdominal PT with varying respiration phases. Furthermore, intraclass correlation coefficients (ICCs) were estimated to quantify the reliability of PT measurements.

Results: The respiration phase has a significant impact on the PT, which was found to be significantly lower during exhalation than during inhalation (431 ± 177 vs 492 ± 186 kPa, p = 0.0003). The pressure application rate (PAR) for the expiratory measurements was significantly lower compared to the inspiratory PAR (112 ± 56 vs 130 ± 63 kPa/s, p = 0.0007). Both ICCs had similar magnitudes (close to 0.9). No significant difference in PT was found between sexes.

Conclusions: Our study underscores the impact of respiration on pain perception, revealing increased abdominal PT during inhalation. A standardized approach is needed for abdominal PT assessment to guarantee its success in diagnostic and therapeutic evaluations.