Gastroscopy is an invasive procedure, generally performed under procedural sedation to ensure patient comfort. The protocol utilized aims to achieve rapid induction, precise effect, stable hemodynamics, rapid recovery, and minimal adverse reactions (1–3). Patients undergoing gastroscopy often experience complications related to the cardiovascular or respiratory systems, making it challenging to perform the procedure safely and effectively while maintaining stable hemodynamics and minimizing respiratory depression (4). Hence, the selection of appropriate sedatives is crucial.

Propofol stands out as one of the most commonly used sedatives in various endoscopic procedures due to its high lipid solubility, rapid crossing of the blood–brain barrier, quick onset of action, and short recovery period (5, 6). A multicenter study revealed that approximately 30% of gastrointestinal endoscopies were conducted using propofol (7). However, respiratory and circulatory depression and injection pain represent the most common side effects of propofol, significantly limiting its usage. Etomidate, another widely used sedative in clinical practice, shares similar properties with propofol and finds extensive application in gastroscopy (8). It is a short-acting intravenous drug that offers distinct advantages in hemodynamics and respiration compared to propofol, with minimal impact on heart rate and blood pressure, rendering it safe for use in patients with unstable cardiovascular systems (9). Its rapid onset, short recovery time, stable hemodynamics, and mild respiratory depression provide reliable procedural sedation conditions for comfortable medical procedures (10). Although etomidate has a lower incidence of respiratory arrest and hypoxemia, as well as reduced injection pain, and does not increase the risk of postoperative nausea and vomiting, it does exhibit a higher occurrence of myoclonus and postoperative nausea and vomiting (11).

Observations indicate that the pharmacological characteristics of etomidate and propofol complement each other, and researchers have tried to highlight the benefits of both drugs and reduce the adverse reactions produced by single drug use by using a combination of etomidate and propofol. Nevertheless, considerable controversy surrounds the optimal ratio of the two drugs in the mixture, leading to potential variations in sedative effects and the incidence of adverse reactions such as hypotension, respiratory depression, myoclonus, and postoperative nausea and vomiting. Consequently, this study employed an etomidate/propofol mixture for sedation during gastroscopy to investigate the appropriate ratio of the two drugs.

With the increasing demand for gastroscopy examinations due to the widespread use of gastrointestinal endoscopy, ensuring patient comfort while addressing new challenges for medical professionals becomes paramount. Anesthetic drugs play a pivotal role in achieving this balance. The study suggests that the use of an etomidate/propofol mixture (especially EP2 group, 10 mL propofol + 10 mL etomidate) could result in better hemodynamic stability during gastroscopy compared to propofol alone. This could be particularly beneficial for patients with cardiovascular concerns or those at higher risk of hemodynamic instability.

Propofol stands out as the primary agent in painless gastroscopy procedures due to its rapid onset, short duration of action, and swift recovery, along with its ability to mitigate postoperative nausea and vomiting (12). However, its respiratory depressant effects may lead to severe hypoxemia post-injection in susceptible patients (13). Furthermore, propofol’s potential to induce significant hypotension poses risks of compromised organ perfusion, increasing the likelihood of cardiovascular incidents (14). Additionally, propofol may cause injection pain, which may be related to direct stimulation of blood vessels or indirect stimulation of bradykinin and prostaglandin production (15, 16). It may even lead to serious complications such as acute refractory bradycardia leading to arrest (17). In our investigation, the incidence of hypotension following propofol administration alone reached 50%, with 55.5% reporting injection pain, and a proportion of low SpO₂ below 90% as high as 18.5%. Etomidate acts primarily by enhancing the activity of the neurotransmitter GABA (gamma-aminobutyric acid) at its receptor in the central nervous system (18) and maintains more stable hemodynamics compared to many other sedatives, such as propofol. This characteristic renders etomidate particularly suitable for elderly patients with unstable circulation (19, 20) and exhibits a significantly lower incidence of injection pain compared to propofol (21). Despite these advantages, sole administration of etomidate can precipitate muscle spasms, postoperative nausea and vomiting, muscle pain, and potentially diminish adrenal function among other adverse reactions (22). Therefore, relying solely on etomidate for medical procedural sedation aimed at comfort might not be optimal. Exploring combination regimens that include etomidate plus other drug could offer a more balanced approach to procedural sedation, reducing adverse effects while enhancing patient comfort and safety.

Propofol also enhances GABAergic neurotransmission, thereby producing sedative effects (23, 24). Due to its pharmacological properties, the combination of propofol and etomidate presents a suitable solution for optimizing sedation during gastroscopy procedures. The synergistic effect of both drugs has been shown to mitigate adverse reactions associated with the individual application of propofol or etomidate, rendering the combination not only safer but also more effective (25, 26). In our study, we explored different volume ratios in the etomidate/propofol combination, including a 1:2 ratio (EP1 group) and a 1:1 ratio (EP2 group). The results demonstrated a noteworthy reduction in hemodynamic changes, muscle spasms, and injection pain compared to the separate use of propofol. Interestingly, the percentage decrease in mean arterial pressure (MAP) was more pronounced in the propofol group (P group) at 19.1%, compared to 18.8% in the EP1 group and 13.8% in the EP2 group. The incidence of hypotension followed a similar trend, with 50% in the P group, 31.5% in the EP1 group, and 11.1% in the EP2 group. From a hemodynamic perspective, our findings suggest that a higher proportion of etomidate contributes to more stable hemodynamics and a lower incidence of hypotension. Respiratory outcomes also favored the combination approach, as all three groups exhibited a decrease in SpO2, with the most significant decrease observed in the propofol group. At the T2 time point, the SpO2 levels in the EP1 and EP2 groups were higher than those in the P group (p < 0.05), and the incidence of hypoxemia in the EP1 and EP2 groups was significantly lower (18.5% vs. 3.7% vs. 3.7%). These results support the notion that combining propofol and etomidate of the 1:1 ratio in achieving stable hemodynamics and minimizing hypotension during gastroscopy procedures. However, there are also studies with different views. Lina et al. (27) reported a lower incidence of adverse reactions with a 1:2 volume ratio compared to the 1:1 ratio. Of course, the choice of etomidate/propofol ratio should consider factors such as patient characteristics, procedural complexity, treatment goals, drug dosage, and administration speed, these factors influence the outcome of the study (28–30). Patients with comorbidities or increased sensitivity to sedatives may benefit from lower etomidate doses to minimize hemodynamic instability (31, 32). Conversely, in lengthy or challenging procedures, a higher propofol concentration may be warranted to ensure adequate sedation depth.

Propofol is the main factor causing injection pain. Despite the administration of dezocine at a dose of 50ug/kg before administration of the sedatives, the P group exhibited a substantial incidence of injection pain at 55.5%, while the EP1 and EP2 groups showed significantly lower rates at 27.8% and 5.5%, respectively. Notably, the EP2 group demonstrated a notable reduction in injection pain incidence, suggesting a correlation with the etomidate mixture ratio. Higher etomidate ratios were associated with lower injection pain rates, potentially due to etomidate’s ability to diminish vascular intima stimulation (33). Additionally, our study revealed that although the P group had a higher proportion of injection pain, it mainly presented as mild pain [with a Visual Analog Scale (VAS) score of 1–3], not requiring any specific intervention.

This study has some limitations. Firstly, we have chosen the ASA I/II classification and an age range of 18–65 years, encompassing a wide demographic. The exclusion of high-risk populations may limit the generalizability of our findings, as different populations may exhibit varied responses to propofol/etomidate. Our primary focus on monitoring MAP changes after sedative administration may impact the adequacy of the sample size assessment. we recognize that the limitation in sample size may have affected the generalizability and reliability of our results. In future studies, we plan to increase the sample size of different populations to ensure a more representative dataset, thereby enhancing the credibility of our research findings. Second, the study details the incidence of adverse events such as hypotension and hypoxemia but does not fully explore all potential adverse reactions that could be associated with the sedative protocols used. A more comprehensive analysis of adverse events would provide a fuller safety profile of the sedative regimens. Third, the study only investigated a limited range of two ratios of etomidate/propofol, while there are infinite possible ratios. Other ratios may produce different effects, so future research could consider expanding the ratio range to comprehensively evaluate the effects of this drug combination. Therefore, further research is necessary to address these limitations.

The use of a mixture of 10 mL etomidate and 10 mL propofol (at a 1:1 ratio) combined with dezocine for painless gastroscopy demonstrates hemodynamic stability, a low incidence of adverse reactions. These findings suggest its potential for clinical application and anesthesiologists should consider incorporating the 1:1 etomidate-propofol combination into their sedation protocols during gastrointestinal endoscopy, especially for patients who may be at a higher risk of hypotension or other adverse effects when using propofol alone.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The studies involving humans were approved by Medical Ethics Committee of the Shunde Hospital of Southern Medical University. The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study.

ST: Writing – original draft. YuZ: Data curation, Writing – review & editing. XL: Writing – review & editing, Methodology. YiZ: Writing – review & editing, Data curation, Investigation. ZZ: Writing – review & editing, Conceptualization.