Background：Hemodynamic instability is a frequent adverse effect following administration of dexmedetomidine (DMED). In this study, we evaluated the incidence of DMED-induced hemodynamic instability and its predictive factors in clinical regional anesthesia practice.
Method: One hundred sixteen patients who underwent orthopedic upper limb surgery under brachial plexus block with intravenous DMED administration were retrospectively identified. The primary outcome was the incidence of DMED-induced hemodynamic instability. The participants were allocated to a stable or unstable group by their hemodynamic instability status. Patients' characteristics were compared between the groups. The relationship between the potential risk factors and development of DMED-induced hemodynamic instability was analyzed with a logistic regression model.
Result: DMED-induced hemodynamic instability was observed in 14.7% of patients (17/116). The unstable group had more women than the stable group (76.5% vs. 39.4%, P = 0.010). When patients were classified into four subgroup according to body mass index (underweight, normal weight, overweight, and obesity), there was significant difference in the composition of the subgroups in the two groups (P = 0.008). In univariate analysis, female sex, obesity, and pre-existing hypertension were significant predictors of DMED-induced hemodynamic instability. Multivariate analysis demonstrated that female sex (adjusted OR 3.86, CI 1.09; 13.59, P = 0.036) and obesity (adjusted OR 6.41, CI 1.22; 33.57, P = 0.028) were independent predictors of DMED-induced hemodynamic instability.
Conclusion: Female and obese patients are more likely to have hemodynamic instability following intravenous DMED administration in clinical regional anesthesia practice. This study suggests that DMED dose may be diminished to prevent hypotensive risk in these populations.