Fluids, Electrolytes, Acid-Base Disorders, and Nutrition Support
Patient Cases
amino acids, and 60 g of lipid daily. She has normal renal and hepatic function. Her most recent ABG from
the morning shows a pH of 7.30, Pco2 55 mm Hg, Po2 96 mm Hg, and HCO3 31 mEq/L. Her fingerstick BG
values from the past 24 hours are 180–200 mg/dL. Which would be best to recommend regarding her PN?
Questions 11–12 pertain to the following case.
A 60-year-old man (weight 65 kg; about 90% IBW) is admitted for acute pancreatitis. After 4 days, he still
has significant abdominal pain and distension without resolution. He has a fever, and blood/urine cultures are
obtained. A CT scan of the abdomen reveals an ileus and an intra-abdominal abscess. He is given a goal PN regi-
men containing 300 g of dextrose, 70 g of amino acids, and 40 g of 20% lipids daily.
SCCM/ASPEN (2016) (JPEN J Parenter Enteral Nutr. 2016;40:159-211): Early EN should be initiated
within 24 to 48 hours in the critically ill patient who is unable to maintain volitional intake once the
patient is hemodynamically stable. It is suggested that very early EN (within 4-6 hours, if possible) be
initiated in a patient with burn injury.
early rather than a complete fast or only intravenous glucose in critically ill patients with sepsis or septic
shock who can be fed enterally.
ESPEN ICU guidelines (2023) (Clin Nutr. 2023;42:1671-1689): If oral intake is not possible and there are
no contraindications to EN, EN should be initiated within 48 hours rather than delaying EN or initiating
PN.
Summary: The data are confusing because several studies have used different times for the definition
of early nutrition therapy: 24, 36, 48, and 72 hours. Most evidence-based clinicians would suggest that
EN therapy be initiated for most patients within 48 hours of ICU admission and no later than 72 hours.
Surgical ICU patients, including those with trauma and thermal injury, have been more consistently
shown to benefit from early EN than medical ICU patients, for whom results are more variable.