Painful regional anaesthesia induces an immunological stress reaction: the model of retrobulbar anaesthesia

Abstract

Background and objective Laboratory stress studies found that acute psychological stresses may elicit changes in leukocyte numbers similar to those occurring in physical stresses. Both types of stress evoke – mainly by release of catecholamines – leukocytosis resulting from a release of natural killer cells (NK-cells), of CD8⁺ T-cells, of monocytes and of neutrophils. However, there is little proof that laboratory stress models can be applied to daily clinical routines. As a likely inductor of an immunological stress response the setting of retrobulbar anaesthesia prior to intraocular surgery permits the study of a short-term painful anaesthetic procedure under highly standardized conditions. This was examined in 16 female patients.

Methods Counts of leukocyte subsets, serum cortisol and cardiovascular variables were measured 30 min and 1 min prior to retrobulbar anaesthesia as well as 2, 15 and 45 min afterwards.

Results The setting of retrobulbar anaesthesia induced an increase in total leukocytes [+380 cells μL⁻¹; P < 0.01 (means; significance level)] mainly due to rising counts of neutrophils (+241 cells μL⁻¹, P < 0.01). Of all lymphocyte subpopulations, natural killer cells increased most markedly (+64 cells μL⁻¹; P < 0.01). Furthermore, the retrobulbar block induced an increase in systolic arterial pressure (+15.2 mmHg; P < 0.01).

Conclusion These changes in immunological and cardiovascular variables are considered to be elements of a sympatho-adrenal stress reaction; catecholamines are considered to induce a demargination of leukocytes by binding to β₂-adrenoceptors and by modifying the avidity state of adhesion molecules.