Autonomic nervous system activity during autologous blood donation for orthognathic surgery.

Purpose: The aim of this study was to assess by means of power spectral analysis the immediate response of autonomic regulation that occurs with postural change from supine to sitting position (modified head-up tilt test [m-HUT]) during autologous blood donation (ABD) and postphlebotomy infusion.

Patients And Methods: We investigated 37 healthy adults who required preoperative ABD before elective orthognathic surgery. Measurements were conducted with m-HUT during ABD and postphlebotomy infusion. The data were analyzed using the maximum entropy method and the difference between supine and tilt was determined by analysis of variance.

Results: When m-HUT was conducted at the resting state, cardiac parasympathetic nervous activity was significantly decreased, whereas cardiac and vascular sympathetic nervous activities were significantly increased. When m-HUT was conducted following blood collection, cardiac parasympathetic nervous activity showed a tendency to increase, whereas vascular sympathetic nervous activity was significantly increased. These changes were not observed during postphlebotomy infusion.

Conclusions: The m-HUT, which involves postural change from supine to sitting position, may be useful for observing autonomic nervous activity in the clinical setting. ABD carries the risk of imbalance of autonomic regulation. However, postphlebotomy infusion may reduce this imbalance.