IMMUNOMODULATION - AN IMPORTANT CONCEPT IN MODERN ANESTHESIA

This review summarises evidence for immunomodulatory effect of drugs a dministered peri-operatively. The clinical significance of the balance of pro- and anti-inflammatory cytokines may be seen in certain diseas e states, for example, meningococcal meningitis and Lyme arthritis. Th is balance may be altered peri-operatively. Traditionally, these chang es are considered to be due to the stress response of surgery, the res ponse to cardiopulmonary bypass, or endotoxaemia. This review presents in vitro evidence suggesting that drugs modulating this cytokine bala nce include non-steroidal anti-inflammatory agents, phosphodiesterase inhibitors and opioids, acting through effects on intracellular cyclic messenger systems. An important consequence of the pro-inflammatory c ytokine activity is increased adhesion of neutrophils. Aspects of this process may be inhibited by avoiding low blood flow states, by reduci ng adhesion molecule expression (for example by use of pentoxifylline) , or by use of negatively charged anions such as heparin. Neutrophil a ctivity is generally depressed by intravenous anaesthetic induction ag ents, but is enhanced by opioids. Natural killer cell activity, which is involved in immunity against tumour cells and virally infected cell s is transiently depressed by volatile anaesthetic agents and opioids. In contrast catecholamines enhance natural killer cell activity. Wher eas decrease in immunoglobulin levels occur peri-operatively, this is not thought to be as a result of drugs at clinically used concentratio ns but rather due to haemodilution.