Fluids, Electrolytes, Acid-Base Disorders, and Nutrition Support

patients had no comorbidities and barely met the criteria for high nutrition risk with an NRS-2002

score of 3 for most patients).

ESPEN ICU guidelines (2023) (Clin Nutr. 2023;42:1671-1689): The safety and benefits of PN should

be weighed on a case-by-case basis for patients who do not tolerate EN at goal. When EN is not

feasible for patients at high nutrition risk or those who are severely malnourished, initiation of

low-dose PN should be carefully considered and balanced against the risks of overfeeding and

refeeding.

Summary: When to initiate SPN in a critically ill patient remains controversial. The 2016 SCCM/

ASPEN guidelines recommend that SPN be considered in all patients unable to receive at least 60%

of target EN by 7–10 days, and the 2022 ASPEN guidelines recommend against SPN initiation prior

to day 7 of ICU admission. However, supporting evidence has notable limitations. Many of the

patients in the Casaer study should not have been given PN in the first place as it was not indicated.

The majority of those patients were discontinued from ventilator support within 2 or 3 days, able

to eat, and discharged from the ICU within 4 to 5 days. This study is a reminder that PN should

not be given indiscriminately to patients as supported by the VA Cooperative Trial (1991) because

PN resulted in increased infectious complications in perioperative GI cancer patients who were not

malnourished as opposed to improved morbidity when given to those who were malnourished. The

Heidegger data showed a benefit from supplemental PN in a sicker patient population than Casaer

et al.’s population. Short-term supplemental PN may be indicated for patients who are anticipated

to have prolonged duration of inability to use GI tract, anticipated prolonged duration of ICU stay,

and who are either malnourished or who have a high level of catabolism. An evaluation of selected

studies that support and question the use of supplemental PN was recently published (Nutr Clin

Pract 2018;33:359-69).