How is the energy requirement for ALS calculated?
Body weight and height are important when calculating energy requirements. Body weight is set in relation to the patient’s height. The relationship between body weight and height is determined in the body mass index (BMI).
The BMI is calculated as body weight in kg/(height in meters)². For a person with a height of 1.7 m and a weight of 80 kg, the BMI is calculated as follows: 80 kg/(1.7)2 = 24.7 kg/m2. A BMI below 18.5 kg/m² is considered underweight and in need of treatment. Falling below this limit should be avoided or treated. Regardless of the absolute value of the BMI, the relative decrease in BMI should also be taken into account. A decrease in BMI of more than 10 % compared to the initial weight should lead to targeted nutritional advice and an assessment of energy requirements.
If the energy balance is negative, the BMI falls below the limit range or the BMI steadily decreases, the use of high-calorie liquid nutrition or tube feeding (if a PEG is present) is necessary.