The Safety of Arginine in the Critically Ill Patient: What Does the Current Literature Show?

Arginine, a semi-essential amino acid, is found to decrease under several conditions of critical illness, either due to decreased intake, mucosal absorption or de novo synthesis, and/or concomitantly increased demand. Under stressful situations, several metabolic, inflammatory, and immunological pathways are also triggered, impacting how nutrients may be utilized. In particular, arginine may be degraded by arginase or nitric oxide synthase, leading to different end products which per se influence the patient’s hemodynamic status and response to pathogens. Furthermore, the critically ill patient undergoes a variety of insults that may be marked solely by a physiological response to trauma (e.g., the major gastrointestinal surgical patient) or a more complicated scenario marked by severe sepsis. Nonetheless, several animal and clinical studies have addressed the various critically ill conditions and concluded that supplemental arginine appears safe and potentially beneficial. Several questions still need to be addressed regarding optimal dosing and timing of delivery.