ANESTHESIA AND PERIOPERATIVE IMMUNE FUNCTION

Innate and acquired immunity plays a pivotal role in the host defense response. Pain, stress, necrotic tissue and invading microorganisms ar e known modulators of the complex immune response of patients undergoi ng major surgery. Anaesthesia itself or perioperative interventions of the anaesthesiologist may substantially alter the immune function wit h potential impact on the postoperative course. For instance, transfus ion of allogenic blood and administration of dopamine or metoclopramid e may interfer with immunity. Stress and pain are associated with immu ne tolerance, increased susceptibility to infection and tumor spreadin g in animal models. Thus, anaesthesia may - through modulation of the neurohumoral stress response - indirectly affect immunity of the surgi cal patient. In particular epidural anaesthesia and/or administration of epidural or spinal opioids seem to attenuate the stress response wi th beneficial effects an cellular and humoral immunity. In addition, a naesthetics, such as etomidate, propofol, or thiopentone and opioid an algesics may directly affect function of immune competent cells. Howev er, these actions may only be apparent with high or supraclinical conc entrations and/or long-term exposure. Regarding the latter,evidence su ggests that long-term sedation using thiopentone in neurosurgical pati ents is paralleled by infectious complications in a dose-dependent man ner. At present, no data a re available regarding the significance of the observed alterations associated with various anaesthetic procedure s of the incidence of postoperative complications associated with impa ired immunity, such as infection or metastatic spreading in oncologica l surgery.