How to Calculate TPN With the Mifflin Equation

If you are hospitalized for a condition that prevents you from eating, you still need a source of calories and nutrients. Your doctor may prescribe total parenteral nutrition (TPN), providing your sustenance through an intravenous catheter in your arm. The medical staff uses numerous factors to determine the specific makeup of your TPN. They may use the Mifflin equation, which estimates a patient's basal metabolic rate based on age, weight, gender and height.

Instructions

• 1

  Determine the height (in centimeters), the weight (in kilograms), the age and the gender of the patient. Use the variables "w," "h" and "a" for weight, height and age in the following equations.

• 2

  Use this equation for men: (10 x w) + (6.25 x h) - (5 x a) + 5. This is an estimate of the basal metabolic rate, the amount of calories the patient would burn on a daily basis with no activity at all.

• 3

  Use this equation for women: (10 x w) + (6.25 x h) - (5 x a) - 161.

• 4

  Adjust the basal metabolic rate for the amount of activity the patient takes part in. You'll need to multiply by a factor that will increase as the level of activity goes up. Multiply by 1.2 for a sedentary patient with little or no exercise and up to 1.9 for a patient who engages in hard physical exercise for several hours a day every day. In most cases, a patient on TPN will tend to be moderately to extremely sedentary, so it's unlikely that a large activity factor will be warranted.

• 5

  Remember that the Mifflin equation estimates only the number of calories a patient needs based on physical characteristics and activity. Appropriate levels of various nutrients are also extremely important in designing a TPN regimen for a patient, and the nutritive needs may vary from patient to patient.