Immune response in infants undergoing application of cast: comparison of halothane and balanced anesthesia.

Purpose: To study the immunological effects of two types of anesthesia on the immune response in infants during a minimally stressful surgical procedure.

Methods: The effects of inhalational halothane (halothane + N2O + O2, spontaneous breathing, n = 12) and conventional balanced anesthesia (thiopental + N2O + O2 + fentanyl + vecuronium, mechanical ventilation, n = 12) on immune function were measured in a crossover study in 12 infants undergoing application of casts to the lower extremity or hip joint. Leukocyte and differential counts, lymphocyte subpopulations, spontaneous lymphocyte proliferative responses as well as responses to phytohemagglutinin (PHA), concavalin A (ConA) and pokeweed mitogen (PWM), and serum cortisol concentration were measured before, immediately after and four hours after the end of anesthesia.

Results: Halothane anesthesia was associated with a higher percentage of T helper cells than conventional balanced anesthesia [47.1+/-1.8 (SEM)%, 48.1+/-2.3% and 50.7+/-1.9% before, immediately and four hours after anesthesia vs. 45.7+/-1.7%, 44.0+/-2.3% and 45.1+/-1.9%, respectively, by groups, P<0.05]. Leukocyte count and the percentages of activated T cells, natural killer cells and B cells showed similar alterations in both groups, and no alterations were observed in the percentages of T lymphocytes or T cytotoxic cells. Lymphocyte transformation response to PWM was decreased four hours after anesthesia in the halothane but not in the balanced anesthesia group.

Conclusion: Anesthesia of short duration during minimal surgical stress alters lymphocyte subpopulations and lymphoproliferative responses in infants and, furthermore, halothane anesthesia and balanced anesthesia have different effects.