Introduction
Gastrointestinal endoscopy plays a very important role in the diagnosis
and treatment of gastrointestinal diseases. To facilitate the work of
the gastroenterologist and provide patient comfort, patients are given
sedation during the endoscopic procedures [1,2]. Propofol is a
popular drug during gastrointestinal endoscopy because of its rapid
onset, short duration of action, and minimal adverse effects [3-7].
However, propofol may result in sedation-related adverse events such as,
respiratory depression and hypotension [8]. Adjuvants are usually
needed in endoscopic procedures in order to decrease the propofol dosage
and adverse events [9,10]. Dexmedetomidine, a α2receptor agonist, could be an ideal adjuvant to propofol for endoscopy
because it provides both analgesia and sedation without respiratory
depression [11]. However, the bradycardia caused by dexmedetomidine
was often reported [12-16]. Nonaka T et al. [16]
demonstrated that that the incidence of bradycardia (defined as a pulse
rate ≤ 45 bpm) in the combination of dexmedetomidine with propofol group
was higher than that in the propofol alone group (37.9% vs. 10.3%).
Whether dexmedetomidine is an ideal adjuvant drug to propofol during
gastrointestinal endoscopy is worthy of our further study.
In the present study, we hypothesized that dexmedetomidine could reduce
the median effective concentration (EC50) of TCI
propofol during gastrointestinal endoscopy. The primary endpoint was to
determine the EC50 of TCI propofol with different doses
of dexmedetomidine. The secondary endpoint was to compare the effects of
different doses of dexmedetomidine on heart rate (HR) and mean arterial
pressure (MAP) during gastrointestinal endoscopy.