Stephen A. McClave

Patients with hematological malignancies (HMs) are more frequently admitted now than in the past to the intensive care unit (ICU) due to more aggressive approaches in primary therapy of HMs and the need for critical care support. Pathophysiological alterations derived from HMs and the different hematological therapies, such as chemotherapy, negatively affect gastrointestinal (GI) function, metabolism, and nutrition status. Further, malnutrition strongly influences outcomes and tolerance of the different hematological therapies. In consequence, these critically ill patients frequently present with malnutrition and pathophysiological alterations that create challenges for the delivery of medical nutrition therapy (MNT) in the ICU. Frequent screening, gauging tolerance, and monitoring nutrition status are mandatory to provide individualized MNT and achieve nutrition objectives. The present review discusses how HM impact GI function and nutrition status, the importance of MNT in patients with HM, and specific considerations for guidance in providing adequate MNT to these patients when admitted to the ICU.

The early provision of soluble/insoluble fiber to the patient who is critically ill has been controversial in the past. Especially in the setting of hemodynamic instability, dysmotility, or impaired gastrointestinal transit, fear of inspissation of formula with precipitation of nonocclusive mesenteric ischemia (NOMI)/nonocclusive bowel necrosis (NOBN) limited its utilization by medical and surgical intensivists. The incidence of NOMI/NOBN has been estimated at 0.2%–0.3% for all intensive care unit (ICU) patients receiving enteral nutrition (EN), and the occurrence of inspissated formula is even less. The science supporting a benefit from providing fiber has recently increased exponentially. The fermentation of soluble fibers leading to the production of short chain fatty acids supports gut barrier function, modulates immune responses, and promotes refaunation of commensal organisms. The “butyrate effect” refers to local (gastrointestinal tract) and systemic anti‐inflammatory responses mediated by the M2 polarization of macrophages, inhibition of histone deacetylase, and stimulation of ubiquitous G protein receptors. Both soluble and insoluble fiber have been shown to promote intestinal motility, reduce feeding intolerance, and shorten hospital length of stay. The benefit of providing dietary fiber early upon admission to the ICU outweighs its minimal associated risk. The point at which the intensivist determines that is safe to initiate EN, both soluble and insoluble fiber should be included in the enteral formulation.