Abstract

INTRODUCTION Limb and respiratory muscle weakness acquired in the intensive care unit (ICU) are commonly associated with longterm functional impairments. However, the extent to which axial muscles might be affected remains poorly understood. Therefore, this study aims to explore the association between axial muscle performance assessed through a supine bridging activity and physical function across critical illness recovery. Secondarily, we investigated the predictability of the supine bridging activity with the walking ability. METHODS Prospective observational study of patients who walked independently before admission and were mechanically ventilated for >= 48 hours in a Chilean medical ICU. The assessment session, conducted on awakening, ICU discharge, and high-dependency unit (HDU) discharge, included the supine bridging activity (performance scored from 0 to 5, with higher scores representing better performance, and lifting duration in seconds) and walking ability. Performance over-time was compared by Friedman's test for multiple comparisons (Bonferroni corrections). Logistic regressions were used to explore the association of supine bridging activity with in-hospital walking ability. We also produced a Receiver Operating Characteristic curve for the predictability of walking ability. RESULTS We enrolled 33 adults, completing 86 supine bridging activity assessments across time points. Supine bridging activity performance improved significantly overtime, with a median (P25 to P75) of 2 (1 to 4) on awakening, 3 (1 to 5) at ICU discharge, and 5 (2 to 5) at HDU discharge (p<0.001). Higher supine bridging activity scores on awakening were associated with a significantly higher likelihood of walking at HDU discharge (odds ratio: 12.17; 95%CI: 1.36 to 108.68; p=0.025). Lifting >14.5 seconds during the supine bridging activity at awakening predicted walking ability at HDU discharge (area under the curve=0.77). CONCLUSIONS Supine bridging activity performance on awakening was associated with walking ability post ICU discharge, with potential implications on rehabilitation interventions aimed at improving axial muscle strength from early stages of critical illness.