Anesth Pain Med.  2018 Jul;13(3):264-270. 10.17085/apm.2018.13.3.264.

The effects of loading dose administration rate of dexmedetomidine on sedation and dexmedetomidine requirement in elderly patients undergoing spinal anesthesia

• Kung HC
• Cheng CC
• Kang DH
• Jeong HJ
• Shin YS
• Kim DS
• Ryu SJ
• Kim KH
• Kim JD

• KMID: 2436033
• DOI: http://doi.org/10.17085/apm.2018.13.3.264

Abstract

BACKGROUND
This study evaluated the effect of decrease in loading dose administration rate of dexmedetomidine (DMT) on sedation and DMT requirement in elderly patients.
METHODS
Fifty-eight patients over 65 years old with ASA I-II who were planned to receive DMT sedation during spinal anesthesia were randomly assigned to two groups. Group S (n = 29) received a 0.5 µg/kg DMT loading dose over 20 minutes, while group C (n = 29) received the DMT loading dose over 10 minutes. Then, both groups received a continuous infusion of 0.4 µg/kg/h. The sedative status was recorded before and at 5, 10, 15, 20, 25, and 30 minutes after administration of DMT and at the end of the anesthesia according to the Ramsay sedation scale (RSS). Also, the time to reach RSS-3 (patients asleep, responsive to commands) and the dose of DMT until reaching RSS-3 were recorded.
RESULTS
The time to reach RSS-3 was similar between the two groups (group S = 16.0 ± 4.3 minutes vs. group C = 15.5 ± 4.2 minutes, P = 0.673). However, the DMT required to reach RSS-3 in group S was significantly lower than that in group C (23.3 ± 7.1 vs. 32.5 ± 6.0 µg, P < 0.001). There was no difference in RSS between the two groups from the administration of DMT to the end of the anesthesia (P = 0.927).
CONCLUSIONS
Decreasing the administration rate of the DMT loading dose did not delay the onset of RSS-3 sedation and reduced the DMT requirement in elderly patients.

Keyword

Adrenergic alpha-2 receptor agonists; Aged; Dexmedetomidine; Hypnotics and sedatives; Spinal anesthesia

MeSH Terms

Adrenergic alpha-2 Receptor Agonists
Aged*
Anesthesia
Anesthesia, Spinal*
Dexmedetomidine*
Humans
Hypnotics and Sedatives
Adrenergic alpha-2 Receptor Agonists
Dexmedetomidine
Hypnotics and Sedatives

Figure

• 

  Fig. 1 Simulated time courses of plasma dexmedetomidine concentrations after a loading dose of 0.5 μg/kg over 10 or 20 minutes, and after zero-order infusion at the rate of 0.4 μg/kg/h for 50 or 40 minutes in a hypothetical patient weighing 60 kg. The pharmacokinetic parameters used in the simulations were obtained from results of Iirola et al. [14] and Angst et al. [15]. RSS: Ramsey sedation scale.

• 

  Fig. 2 Changes in Ramsey sedation scale (RSS). Graph shows the mean values and standard deviations. Group S: a loading dose of dexmedetomidine (DMT) of 0.5 μg/kg over 20 minutes, followed by a continuous infusion of 0.4 μg/kg/h. Group C: a loading dose of DMT of 0.5 μg/kg over 10 minutes, followed by a continuous infusion of 0.4 μg/kg/h. There was no significant difference between the two groups (P = 0.927). BA: before administration of DMT, A5, A10, A15, A20, A25, A30: 5, 10, 15, 20, 25 and 30 minutes after administration of DMT, EA: end of anesthesia.

• 

  Fig. 3 Changes in mean arterial pressure (MAP). Graph shows the mean values and standard deviations. Group S: a loading dose of dexmedetomidine (DMT) of 0.5 μg/kg over 20 minutes, followed by a continuous infusion of 0.4 μg/kg/h. Group C: a loading dose of DMT of 0.5 μg/kg over 10 minutes, followed by a continuous infusion of 0.4 μg/kg/h. A significant effect of time (P < 0.001) and no significant interaction between time and group (P = 0.422) are shown. BA: before administration of DMT, A: immediately after administration of DMT, A10, A20, A30: 10, 20 and 30 minutes after administration of DMT, EA: end of anesthesia.

• 

  Fig. 4 Changes in heart rate (HR). Graph shows the mean values and standard deviations. Group S: a loading dose of dexmedetomidine (DMT) of 0.5 μg/kg over 20 minutes, followed by a continuous infusion of 0.4 μg/kg/h. Group C: a loading dose of DMT of 0.5 μg/kg over 10 minutes, followed by a continuous infusion of 0.4 g/kg/h. A significant effect of time (P < 0.001) and no significant interaction between time and group (P = 0.247) are shown. BA: before administration of DMT, A: immediately after administration of DMT, A10, A20, A30: 10, 20 and 30 minutes after administration of DMT, EA: end of anesthesia.

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