To determine the relationship between cumulative fluid balance, muscle mass quality, and strength in critically ill patients under deep sedation and mechanical ventilation.
This retrospective observational study was conducted in the ICU at Clínica Alemana, Chile. Patients over 18 years old who required deep sedation, mechanical ventilation, and a minimum stay of 24 hours were included.
Muscle quality was assessed in the quadriceps using the Heckmatt scale, and ultrasound measurements were performed with a Philips iu22 ultrasound machine. The measurements were carried out by a certified physiotherapist. Muscle strength was measured using the MRC-SS scale. Daily fluid balance was calculated as the difference between fluids administered and eliminated. For statistical analysis, the Permutation Test was applied to assess the relationship between fluid balance and muscle quality, and the Spearman coefficient was used to evaluate the relationship between fluid balance and muscle strength.
The study included 50 patients with a mean age of 51 ± 14 years, an average APACHE II score of 20 (range 15 to 25), and a mean duration of mechanical ventilation of 5 ± 1.6 days.
The mean initial fluid balance was 1095.1 ml, while the mean final fluid balance reached 2691.96 ml. Regarding muscle quality, measured using the Heckmatt scale, the initial median was 2, and the final median was 3. The analysis performed using the Permutation Test showed a significant difference between cumulative fluid balance and muscle quality, with a p-value of 0.0018.
Muscle strength, measured by the MRC-SS scale upon awakening, had a mean of 35.3. The final cumulative fluid balance and muscle strength showed a Spearman's rho = -0.78 and a p-value of 0.005.
The study concludes that cumulative fluid balance is associated with a decrease in muscle quality and greater muscle weakness.
This study has key implications for clinical practice and physiotherapy management. The results show that cumulative fluid balance affects muscle quality and strength in critically ill patients, highlighting the need for more precise fluid management in the ICU. Ultrasound, along with fluid balance monitoring, could be routinely integrated to improve clinical outcomes.
In terms of management and policies, the study could drive the creation of protocols that incorporate fluid balance assessment into physiotherapy decision-making.
Ultrasound
ICU-acquired weakness
