In this study, our data showed that a dexmedetomidine-based sedation regimen provided a superlative degree of safety, with minimal respiratory inhibition during ERCP with no downstream effects on procedural efficacy when compared with propofol sedation.
ERCP is an essential diagnostic and therapeutic method for biliary and pancreatic diseases, generally conducted under anesthesia due to its painful and time-consuming properties. Sedation without intubation administered by an anesthesiologist appears to be the most recommended strategy for ERCP due to a reduced incidence of adverse discharge [15]. Propofol is the mainstay sedative for sedation without intubation during gastrointestinal endoscopy for its outstanding characters of potent action, rapid onset, and fast recovery [16]. However, doubts concerning its sedation-related side effects hinders its widespread clinical application, particularly during ERCP for elderly populations and those requiring prone positions. Indeed, previous studies reported a high incidence of hypotension (4.8–19%) and hypoxemia or apnea (3.3–60.7%) under propofol sedation during ERCP [6, 14, 17, 18]. Dexmedetomidine is a highly selective α-2-adrenoceptor agonist with sedative, analgesic, and anxiolytic properties. Balanced dexmedetomidine administration with opioids and benzodiazepine could be an alternative and safer method to propofol during advanced endoscopic procedures. However, to our knowledge, the data are limited on the sedation efficacy and safety of dexmedetomidine combined with opioids and benzodiazepine administration when compared with propofol during ERCP.
Several controlled randomized trials investigated the sedation efficacy of dexmedetomidine combined with opioids and benzodiazepines during ERCP procedures [4, 19]. Lu et al. [4] demonstrated that 95% of patients completed ERCP without discomfort and additional sedative-use under dexmedetomidine and remifentanil anesthesia. Ikeda and colleagues [19] showed that combination treatments with dexmedetomidine and benzodiazepines provided high-quality sedative effects with rare excessive movement. Consistent with previous results, all patients in our study achieved the targeted RSS sedation level, and completed the procedure without premature termination. Moreover, RSS sedation levels and BIS scores were similar between groups after bolus administration with no significant differences in the requirement of rescue agents.
A previous meta-analysis reported that propofol provided a higher level of satisfaction when compared with dexmedetomidine in patients undergoing gastrointestinal endoscopy [20], while another meta-analysis demonstrated a higher satisfaction of endoscopic performers were rated for dexmedetomidine-based sedation when compared with propofol [21]. In the present study, we demonstrated comparable satisfaction levels among endoscopic performers and patients when different anesthetic agents were used. Such a discrepancy may be attributed to the synergistic effects of opioids and benzodiazepines when added to dexmedetomidine sedation [10]. Additionally, the effect of suppressing gastric motility with dexmedetomidine-based sedation may contributed to the improved endoscopist satisfaction when compared with propofol [11]. Above all, our study showed that both sedating regimens provided equivalent sedation efficacy with relatively satisfactory levels of sedation.
It was worth noting that sedation depth was transiently deeper at T1 in the PRO group compared to the DEX group. This was due to the rapid onset of propofol activity, which was further verified by the shorter onset time of targeted sedation in the PRO group compared to the DEX group. In terms of shorter onset times, this may be a double-edged sword for sedation. As shown in Fig. 4, MAP and RR were significantly lower in the PRO group at T1. This finding reflected the narrow therapeutic index of propofol and the risk of cardiovascular complications especially during the induction period. This indicated a difficulty in controlling cardiorespiratory stability with propofol, especially in the elderly, by an unexperienced anesthesiologist or under nurse-guided sedation [22]. In contrast, patients in the DEX group had a faster recovery than the PRO group due to the unusual property of its arousable sedation [10]. Patients in the DEX group were aroused immediately by name calling or a shake stimulus after ERCP. Additionally, dexmedetomidine enabled patients to achieve an Aldrete score of 9 at procedure end, and to leave the operation room within 2 min.
Respiratory and cardiovascular suppress are well-known as the side effects of propofol. The features that differentiate dexmedetomidine from propofol are the maintenance of spontaneous breathing and the avoidance of profound cardiovascular compromise during sedation. In our study, MAP was lower after induction but higher during the recovery period under propofol sedation when compared with dexmedetomidine. The short elimination half-life of propofol may be responsible for these differences, in contrast, dexmedetomidine has a relatively slow elimination with cumulative effects leading to a prolonged cardiovascular depression [23]. Consequently, dexmedetomidine and propofol may have similar hypotension risks which may occur throughout the procedure. Dose-dependent respiratory depression is another major concern for propofol treatment [6]. In our study, airway manipulation due to transient hypoxemia was required in 29% of patients, while 81% of cases exhibited a respiratory rate < 10 bpm in the PRO group. Though no different effects on SpO2 were observed between the two segments, fluctuations in values were obvious under propofol sedation. These results agreed with Yang et al. [24] who showed that 28% of patients experienced hypoxemia during propofol sedation. For dexmedetomidine, its major issue is bradycardia resulting from α 2-adrenoceptor activation, and we observed a lower heart rate in the DEX group throughout the study, which could be immediately reversed by the treatment with atropine.
In recent years, several case reports suggested an association between short-term exposure to propofol and acute pancreatitis [25, 26], therefore propofol sedation has raised additional concerns for increasing PEP risks. Our ERCP procedure lasted for 25 min on average and our results showed that such a short-term exposure to propofol exhibited similar risk than application of dexmedetomidine in terms of PEP, consistent with Li et al. [27]. Furthermore, previous investigations indicated that dexmedetomidine may provide superior anti-inflammatory effects and decrease infection risks [28]. However, no significant differences in the incidence of post-ERCP infections were observed between groups. Based on these data, propofol or dexmedetomidine sedation are comparatively safe anesthetics strategy for ERCP without increasing additional risks of ERCP-related adverse events.
The standard recommendation for dexmedetomidine administration method is somewhat complicated, as the loading dose should be given over 10 min followed by an infusion rate of 0.7–1.4 µg•kg− 1•h− 1[12]. However, data from previous studies demonstrated that 0.5 µg•kg− 1 dexmedetomidine could be used as a bolus within 30 s in patients, without causing any substantial hemodynamic compromise [18, 29]. Therefore, a 0.6 µg•kg− 1 loading dose of dexmedetomidine over 2 min, alternating with sufentanil and midazolam, were used in our study.
Our study had several limitations. (1) The endoscopist was assumed to be blinded to group assignment, but it was still uncertain whether they could identify sedative agents in terms of physical property differences between dexmedetomidine and propofol. Therefore, we could not completely eliminate the personal bias when they answered questionnaires. (2) Our study included patients with ASA status I–III and < 80 years old in a single center. Older age and an ASA status of III or higher were demonstrated to be independent predictors of developing SRAEs under propofol sedation [24]. Additionally, the beneficial effects of dexmedetomidine-based sedation may have been more apparent in critically ill patients, this factor may have skewed our results.