The aim of this study was to investigate the effect of blood volume reduction (300 – 400 mL) on circulation and Heart Rate Variability (HRV), by using autologous blood donation as a model of blood volume change. In 33 adult subjects (56.3 ± 15.9yrs) with no circulatory, respiratory, or neurologic disease, we measured Blood Pressure (BP) and electrocardiographic parameters during autologous blood donation. We divided the subjects into 3 groups according to age (10–30 yrs, 40–50 yrs, and 60–80 yrs) and into 2 groups according to blood donation experience. In all age groups, the Low‐Frequency power/High‐Frequency power ratio (LF/HF) increased, and the HF power decreased during autologous blood donation. Additionally, during autologous blood donation, the 60–80 yrs age group exhibited the highest variation in HRV. In non‐experienced group, LF/HF decreased after autologous blood donation. Further, 1 subject developed Vaso‐Vagal Reaction (VVR). LF/HF was markedly higher in this subject than in the other subjects before autologous blood donation. After autologous blood donation, the decrease in LF/HF in the subject with VVR was similar that of subjects in the non‐experienced group. In the subject with VVR, BP decreased significantly, and the Heart Rate (HR) did not increase after autologous blood donation. In contrast, in the other subjects, BP decreased mildly and HR increased after autologous blood donation.
A high glycemic status increases the risk for autonomic dysfunction and cardiovascular failure. The aim of this study was to investigate time-dependent changes in the autonomic response and cardiovascular dynamics and the association between the level of hemoglobin A1c (HbA1c) and autonomic response during blood volume reduction. The study population consisted of 26 preoperative participants who were scheduled for autologous blood donation (200-400 mL of whole blood) for intraoperative or postoperative use. These participants without circulatory, respiratory, or brain disease and diabetes mellitus were grouped according to their HbA1c levels: < 6.5% (n = 18) and ≥ 6.5% (n = 8). We measured blood pressure (BP) and analyzed heart rate variability (HRV) to quantify cardiac autonomic regulation throughout blood donation. During blood volume reduction, which was about 10% of the circulating blood volume, the BP and heart rate varied within normal ranges in both groups. The high-frequency (HF) component, an index of parasympathetic nerve activity, and the ratio of low-frequency (LF) to HF components (LF/HF), an index of sympathetic nerve activity, significantly decreased and increased with the progression of blood volume reduction, respectively, in the HbA1c < 6.5% group. In contrast, in the HbA1c ≥ 6.5% group, the HF component did not significantly change, and the increase in the LF/HF ratio was delayed. Time-dependent changes in HRV were related to blood volume reduction only in the HbA1c < 6.5% group. Thus, elevated HbA1c levels are associated with the decrease in the autonomic response induced by blood volume reduction.
Hyperglycemia has been reported as a risk factor for autonomic dysfunction. However, the changes in autonomic nerve activity that occur in hyperglycemic patients during blood volume reduction are unclear. This study aimed to investigate the impact of hyperglycemia (HbA1c 蠅 6.5%) on autonomic nerve activity and cardiovascular dynamics during blood volume reduction (300‐400 mL), by using autologous blood donation as a model of mild blood loss. We compared the impact of hyperglycemia and non‐hyperglycemia on heart rate variability, including circulatory regulation, in 17 patients (mean age 60.9 ± 13.6 years) with no circulatory, respiratory, or cranial nerve disease. During autologous blood donation, none of the patients experienced significant changes in blood pressure or heart rate. In non‐hyperglycemia, the low frequency/high frequency component ratio (LF/HF) significantly increased (p < 0.05) and HF decreased during autologous blood donation. In hyperglycemia, LF/HF and HF responses were lower than in non‐hyperglycemia. These results show that hyperglycemia impaired autonomic regulation during a blood volume reduction of approximately 10% of the circulatory blood volume. This suggests that circulatory failure may be more common in hyperglycemic patients than in non‐hyperglycemic patients during moderate or severe blood volume reduction.
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