The relationship between disease severity and mortality risk in critical care patients with respiratory muscle strength, muscle biomechanical properties and muscle architecture

Aims: Long-term immobilization in critical care (CC) patients negatively affects the respiratory and musculoskeletal systems. Increased disease severity may worsen these systems, but the relationship with muscle strength, biomechanics, and architecture is unclear. Understanding these effects is essential for developing effective physiotherapy strategies. Methods: CC patients who were not on mechanical ventilation were included. Disease severity and mortality risk of was evaluated with the Acute Physiology and Chronic Health Evaluation II (APACHE II) score. The respiratory muscle strength was recorded by maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP). Ultrasonographic measurements were taken from quadriceps femoris (QF) for muscle thickness. Muscle tone was recorded from the rectus femoris (RF) and vastus lateralis (VL) with myotonometer. Results: 31 CC patients with an age of 65.42±8.84 were included. Positive correlation between APACHE II score and right-left VL muscle tone (p=0.041, r=0.370, p=0.294, r=0.195, respectively) and right-left RF muscle tone (p=0.039, r=0.372, p=0.020, r=0.415); A negative correlation was detected between APACHE II score and right-left QF muscle thickness (p=0.001, r=-0.569, p=0.005, r=-0.493) and MIP and MEP (p=0.028, r=-0.394, p=0.045, r=-0.363). Conclusion: An increase in disease severity negatively affects respiratory muscle strength, muscle biomechanics, and muscle architecture. Future studies investigating the impact of respiratory physiotherapy on these parameters may highlight the effect of physiotherapy approaches on clinical state in CC.