When Is It Appropriate to Use Arginine in Critical Illness?

In health, arginine is considered a nonessential amino acid but can become an essential amino acid (ie, conditionally essential amino acid) during periods of metabolic or traumatic stress as endogenous arginine supply is inadequate to meet physiologic demands. Arginine depletion in critical illness is associated with impairments in microcirculatory blood flow, impaired wound healing, and T-cell dysfunction. The purpose of this review is to (1) describe arginine metabolism and role in health and critical illness, (2) describe the relationship between arginine and asymmetric dimethylarginine, and (3) review studies of supplemental arginine in critically ill patients.