Immunomodulatory effects of anesthetic agents in perioperative medicine

Anesthetics comprise a heterogeneous group of drugs with multiple functions and mechanisms of action, which are not yet fully elucidated. In the clinical setting, it is difficult to isolate the effects of anesthetic agents from those of surgical stress itself or of other individual covariates. For this reason, several methods involving human immune cells and animal models have been used to study the effects of anesthetic agents on the immune system. The immunomodulation caused by anesthetic agents may lead to distinct consequences: suppression of the immune response, preventing or minimizing further distal organ injury; or suppression of the host immune reaction, which can lead to unacceptably increased risk of opportunistic infections. This review discusses the perioperative inflammatory response and the immunomodulatory properties of the most commonly used anesthetic agents in the perioperative period, addressing both their effects and proposed mechanisms of action on the innate immune system, including: biochemical and cellular defenses; barriers such as the endothelium and epithelium; biological macromolecules; domain proteins; specific cell types; and molecules such as cytokines and chemokines, which coordinate the host defense process. The immunomodulatory consequences of general anesthesia are complex. Immunosuppression can lead to beneficial effects, reducing systemic and local inflammation, or negative effects, which result in increased risk of infection. Anesthesiologists should choose the most appropriate agents based on the immune status of each patient.