Impact of Nonselective and Selective α-1 Adrenergic Blockers on the Sedative Efficacy of Dexmedetomidine in Urologic Surgery: A Prospective, Observational Study

Abstract

BACKGROUND This study aimed to compare the impact of a-1 adrenergic blockers - nonselective (alfuzosin, doxazosin, and terazosin) and selective (silodosin and tamsulosin) - on the sedative effects of the alpha-2 adrenergic agonist dexmedetomidine (DMT) in patients undergoing urologic surgery. The primary outcome was the sedative effect of DMT as determined by the bispectral index (BIS) and Modified Observer's Assessment of Alertness/Sedation (MOAA/S) scale scores. MATERIAL AND METHODS One hundred eighteen patients undergoing elective urologic surgery with spinal anesthesia were recruited. Patients were assigned based on their medication status to group N (no medication; n=33), group NS (nonselective alpha-1 blocker; n=27), or group S (selective alpha-1 blocker; n=58). Mean blood pressure (MBP), heart rate (HR), oxygen saturation (SpO₂), BIS, and MOAA/S scale scores were recorded at 5-minute (min) intervals after DMT administration. RESULTS Group NS had significantly higher BIS scores than groups N and S at 25 min (P=0.045) and 30 min (P=0.030) after DMT administration, indicating lower sedation levels. MBP significantly differed between the 3 groups at all time points, with group N experiencing a lower MBP than groups NS and S. No significant differences were found between the groups in MOAA/S scale scores, SpO₂, or HR. CONCLUSIONS Nonselective alpha-1 adrenergic blockers can reduce the sedative effects of DMT. Consequently, there may be a need for individualized anesthesia management considering the specific subtype of alpha-1 adrenergic blocker medication.

Figure 1

Study flow diagram. Design of the study to compare the impact of different types of α−1 adrenergic blockers on the sedative effects of the α−2 adrenergic agonist dexmedetomidine in 118 patients undergoing urologic surgery. Group N – no medication group; Group NS – nonselective α−1 blocker medication group; Group S – selective α−1 blocker medication group. This Figure was created by MS PowerPoint, version 2016, Microsoft.

Figure 2

The changes in the bispectral index (BIS) (A), Modified Observer’s Assessment of Alertness/Sedation (MOAA/S) scale (B), heart rate (HR) (C), and mean blood pressure (MBP) (D) after dexmedetomidine administration. After dexmedetomidine administration, group NS showed less sedation than groups N and S, as evidenced by higher BIS scores at 25 and 30 minutes. Group N consistently had lower MBP than groups NS and S. However, the MOAA/S scale and HR were similar across all groups. Data are presented as the median and interquartile range (IQR). * P<0.05 (group NS vs groups N and S) and ** P<0.01 (group N vs groups NS and S). ART-RMANOVA, aligned rank transformed ANOVA. Group N – no medication group; Group NS – nonselective α−1 blocker medication group; Group S – selective α−1 blocker medication group. BIS – bispectral index; MOAA/S scale – Modified Observer’s Assessment of Alertness/Sedation scale; HR – heart rate; MBP – mean blood pressure. This figure was created by MedCalc, version 20, MedCalc Software, Ltd.