Manual of Clinical Nutrition

Parenteral Nutrition Support for Adults

Manual of Clinical Nutrition Management B- 57 Copyright © 2013 Compass Group, Inc.

Table B-7: Monitoring Hospitalized Patients Receiving CPN (18, 44)
Metabolic or Clinical Parameter Monitoring Frequency
Blood glucose Every 6 hours until stable; 100 to 150 mg/dL in
critically ill patients (6,16,20,44) and 140 to 180 mg/dL
in critically ill diabetic patients (19)
Electrolytes (Na, K, Cl), CO 2 , blood urea nitrogen,
creatinine, Mg, Caa, phosphorus

Baseline, daily until stable, then two or three times per
week
Total bilirubin, liver function tests (alanine
aminotransferase, aspartate aminotransferase, and
alkaline phosphatase)

Baseline, daily until stable, then weekly

Complete blood cell count with differential Baseline, then weekly
Prothrombin time/partial thromboplastin time Baseline, then weekly
Albuminb Baseline, then as needed (>21 days)
Prealbuminb Baseline, then weekly
Transferrinb Baseline, then weekly
Nitrogen balance As needed
Weight Daily until stable, then two or three times per week
Vital signs (temperature, pulse, blood pressure,
respiratory rate)

Every 8 hours as needed

a Half of total calcium (Ca) is protein bound; therefore, during hypoalbuminemia, the true calcium status may not be represented by
measuring serum calcium levels. There is a 0.8 mg/dL decrease in the total concentration of serum calcium for each 1.0 mg/dL decrease
in the albumin concentration below 4.0 g/dL. Correct serum calcium can be estimated by the following formula: Ca++ (mg/dL) = Measured
Ca++ (mg/dL) + 0.8  [4.0 – Albumin (g/dL)] (44). However, this formula provides only an estimate and a review of the evidence suggests
this formula may actually overestimate the corrected calcium concentration in critically ill patients (45). When an accurate evaluation is
needed, the ionized calcium level should be obtained (44).^

b (^) The levels of acute phase hepatic proteins (albumin, prealbumin, and transferrin) can decrease by as much as 25% as a result of acute or
chronic inflammatory conditions and are no longer reliable indicators in critically ill patients. This decrease impacts their usability in
determining nutrition repletion. If inflammatory markers (eg, C-reactive protein) indicate an inflammatory metabolism, these proteins
may not be reliable indicators of nutritional status. Acute phase hepatic proteins may only be reliable when malnutrition is not
complicated by inflammatory metabolism caused by acute or chronic disease.
See Section III: Clinical Nutrition Management, Parenteral Nutrition: Metabolic Complications of Central
Parenteral Nutrition and Calculating Total Parenteral Nutrition.
Transitional Feeding^ (6)
Cyclic CPN: The infusion of CPN over a limited amount of time (usually 12 to 18 hours) is called cyclic CPN.
Cyclic CPN is indicated for patients who are metabolically stable and for patients who require long-term CPN,
such as patients who receive CPN at home. One advantage of cyclic CPN is that feedings more closely
resemble physiologic (discontinuous) feedings, which may reduce the hepatic toxicity associated with
continuous feedings. Another advantage is improved quality of life, because the patient is free from CPN
equipment during the day.
Transition to cyclic is best done over 2 to 4 days by reducing the infusion time in increments of 4 to 6 hours.
Cyclic TPN should be tapered up 1 to 2 hours (for patients with DM or hyperglycemia) to decrease
hyperglycemia and hypoglycemia (46).
Parenteral to enteral: When the patient is transitioned from parenteral support to enteral support, the tube
feeding can be initiated at full strength (10 to 3 0 mL/hour). As the rate of tube feeding is increased, the rate of
parenteral nutrition is proportionately decreased. Tapering of parenteral formula can begin when enteral tube
feedings are providing 33% to 50% of nutrient requirements. Once enteral tube feedings are well tolerated and
provide more than 60% of energy requirements and 100% of fluid requirements, parenteral nutrition can be
discontinued (6).
Parenteral to oral: When patients are transitioned from parenteral support to an oral diet, oral intake is
started as clear liquids and then progressed in a stepwise fashion to an appropriate diet as tolerated. Nutrient
intake studies should document the adequacy of oral intake. The total parenteral nutrition should be tapered to
half of the original rate when the patient is eating 50% of the total estimated energy needs. The CPN should be
discontinued when oral intake consistently meets 60% of estimated nutrient needs and 100% of fluid needs (6).
If oral intake does not progress to adequate amounts, enteral nutrition should be considered in lieu of PPN or
CPN (6).