Effect of high or low protein nutrition on diaphragm thickness using ultrasonography in mechanically ventilated intensive care patients

Background: Diaphragmatic dysfunction is associated with difficulties from weaning and have worse patient outcomes in intensive care unit (ICU). It is still not clear how to prevent diaphragmatic dysfunction. Protein may be one of the modifiable factors that can prevent diaphragmatic dysfunction. We aimed to compare the effects of low protein and high protein support on diaphragm thickness using ultrasonography in mechanically ventilated patients in the ICU. Methods: This study was performed in intensive care patients over the age of 18 who were mechanically ventilated and administered enteral nutrition. Patients were randomly (using a computer-generated list: 1/1 block randomization) allocated to low protein group (1.1 g/kg/day) or a high protein group (1.5 g/kg/day). The patients’ demographics, diagnosis and comorbidities, length of stay (APACHE II), NRS 2002 scores were recorded on the first day of intubation. Diaphragm thickness and mid arm muscle circumference measurements were taken on the 1st, 7th, and 14th days on mechanically ventilation and day of weaning. Results: 42 Intubated critically ill patients (age 69 ± 15 years, 12 women/30 men) enrolled in this study. Demographics BMI, Apache II score, duration of mechanical ventilation, length of intensive care stay and hospital stay were not different between groups. The diaphragm thickness measured on the 7th day was 1.81 ± 0.29 mm (n=21) in low protein group and 2.00 ± 0.23 mm (n=21) in the high protein group (p= 0.028). The diaphragm thickness measured on the weaning day were 1.73 ± 0.14 mm (n=9) and 2.01 ± 0.21 mm (n=10) in the low protein group and in the high protein group respectively (p= 0.004). Conclusions: Large-scale and long-term studies on this subject may help reveal the differences between the high protein and low protein support for ICU patients.