[Dynamic changes of diaphragm and limb skeletal muscle in patients with sepsis assessed by bedside ultrasound and their correlation with blood urea/creatinine ratio].

Objective: To investigate the dynamic changes of diaphragm and limb skeletal muscle in patients with sepsis by bedside ultrasound and their correlation with the ratio of blood urea/creatinine ratio (UCR) in 7 days after intensive care unit (ICU) admission.

Methods: A prospective observational study was conducted. A total of 55 patients with sepsis admitted to ICU of General Hospital of Ningxia Medical University from June 2022 to February 2023 were selected as the research objects. General information, laboratory indicators [urea, serum creatinine (SCr), and UCR] on days 1, 4, and 7 of ICU admission, and prognostic indicators were observed. Bedside ultrasound was used to assess the dynamic changes of diaphragm morphology [including diaphragmatic excursion (DE), end-inspiratory diaphragm thickness (DTei), and end-expiratory diaphragm thickness (DTee)] on days 1, 4, and 7 of ICU admission, as well as limb skeletal muscle (quadriceps femoris) morphology [including rectus femoris-muscle layer thickness (RF-MLT), vastus intermedius-muscle layer thickness (VI-MLT), and rectus femoris-cross sectional area (RF-CSA)]. Diaphragm thickening fraction (DTF) and RF-CSA atrophy rate were calculated, and the incidence of diaphragm and limb skeletal muscle dysfunction was recorded. The correlation between ultrasound morphological parameters of diaphragm and quadriceps and UCR at each time points in 7 days after ICU admission was analyzed by Pearson correlation.

Results: A total of 55 patients with sepsis were included, of which 29 were in septic shock. As the duration of ICU admission increased, the incidence of diaphragm dysfunction in patients with sepsis increased first and then decreased (63.6%, 69.6%, and 58.6% on days 1, 4, and 7 of ICU admission, respectively), while the incidence of limb skeletal muscle dysfunction showed an increasing trend (54.3% and 62.1% on days 4 and 7 of ICU admission, respectively), with a probability of simultaneous occurrence on days 4 and 7 of ICU admission were 32.6% and 34.5%, respectively. The UCR on day 7 of ICU admission was significantly higher than that on day 1 [121.77 (95.46, 164.55) vs. 97.00 (70.26, 130.50)], and RF-CSA atrophy rate on day 7 was significantly higher than that on day 4 [%: -39.7 (-52.4, -22.1) vs. -26.5 (-40.2, -16.4)]. RF-CSA was significantly lower on day 7 compared to day 1 [cm²: 1.3 (1.0, 2.5) vs. 2.1 (1.7, 2.9)], with all differences being statistically significant (all P < 0.05). Pearson correlation analysis showed that RF-CSA on day 7 of ICU admission was negatively associated with the UCR on the same day (r = -0.407, P = 0.029).

Conclusions: Diaphragmatic dysfunction in patients with sepsis occurred early and can be improved. Limb skeletal muscle dysfunction occurred relatively later and progresses progressively. The RF-CSA on day 7 of ICU admission may be a reliable measure of limb skeletal muscle dysfunction in patients with sepsis, can be an indicator of early identification and diagnosis of ICU-acquired weakness (ICU-AW). Continuous loss of muscle mass occurring in septic patients is mainly associated with persistent organismal catabolism, and undergoes significant changes around a week in ICU.