Endoscopy 2014; 46(09): 817
DOI: 10.1055/s-0034-1377782
Letters to the editor
© Georg Thieme Verlag KG Stuttgart · New York

Reply to Xu et al.

Ban Seok Lee
,
Junghee Ryu
,
Sang Hyub Lee
Further Information

Publication History

Publication Date:
29 August 2014 (online)

We thank Xu et al. for their perceptive comments. They mention that dexmedetomidine exhibits an analgesic effect as well as a sedation effect, and that the duration of action of midazolam is too long for use in endoscopic retrograde cholangiopancreatography (ERCP). They also indicate that the clearance of dexmedetomidine could decrease with increasing severity of hepatic impairment, which was not mentioned in our report, and that the absolute value of the bispectral index may vary between individuals.

First, as we mentioned in our article, dexmedetomidine alone may be insufficient for sedation and analgesia during ERCP. In a previous study [1], 91.7 % of patients who underwent ERCP with dexmedetomidine alone needed additional analgesia during the procedure. As for midazolam, it is widely used as a sedative for ERCP, colonoscopy, and even esophagogastroduodenoscopy in current practice [2] [3]. ERCP is a complex procedure requiring relatively more time than other parallel procedures, and a clinically important disadvantage of dexmedetomidine is the slow onset time of sedation [4].

Second, dexmedetomidine is a high-extraction drug, therefore clearance is mainly affected by hepatic blood flow and less by liver enzyme activity or protein binding [5]. The volume of distribution of dexmedetomidine may be affected by plasma albumin concentration because dexmedetomidine is highly (94 %) bound to plasma proteins [6]. According to previous results, however, clearance of dexmedetomidine is associated with liver blood flow and not albumin concentration [7]. In our study, two patients with alcoholic liver cirrhosis were excluded from enrollment due to alcohol dependency, which was a defined exclusion criterion, and there were no participants with hemodynamic instability or decompensated hepatic failure leading to alteration in albumin level in the study population.

Finally, we agree with the comment regarding individual variability of the bispectral index evaluation. Due to this weakness, the bispectral index score was used as a secondary outcome measure instead of the primary outcome variable in our study.

 
  • References

  • 1 Muller S, Borowics SM, Fortis EA et al. Clinical efficacy of dexmedetomidine alone is less than propofol for conscious sedation during ERCP. Gastrointest Endosc 2008; 67: 651-659
  • 2 Cohen LB, Wecsler JS, Gaetano JN et al. Endoscopic sedation in the United States: results from a nationwide survey. Am J Gastroenterol 2006; 101: 967-974
  • 3 Triantafillidis JK, Merikas E, Nikolakis D et al. Sedation in gastrointestinal endoscopy: current issues. World J Gastroenterol 2013; 19: 463-481
  • 4 Panzer O, Moitra V, Sladen RN. Pharmacology of sedative-analgesic agents: dexmedetomidine, remifentanil, ketamine, volatile anesthetics, and the role of peripheral Mu antagonists. Anesthesiol Clin 2011; 29: 587-605, vii
  • 5 Valitalo PA, Ahtola-Satila T, Wighton A et al. Population pharmacokinetics of dexmedetomidine in critically ill patients. Clin Drug Investig 2013; 33: 579-587
  • 6 Chrysostomou C, Schmitt CG. Dexmedetomidine: sedation, analgesia and beyond. Expert Opin Drug Metab Toxicol 2008; 4: 619-627
  • 7 Iirola T, Ihmsen H, Laitio R et al. Population pharmacokinetics of dexmedetomidine during long-term sedation in intensive care patients. Br J Anaesth 2012; 108: 460-468