Effects of non-intubation anesthesia based on a fentanyl-reduced regimen on hypoxemia during bronchoscopy for older patients: study protocol for a randomized controlled trial
Study Protocol

Effects of non-intubation anesthesia based on a fentanyl-reduced regimen on hypoxemia during bronchoscopy for older patients: study protocol for a randomized controlled trial

An Xie1, Xianjie Zhang1, Jia Han1, Rui Zhou2 ORCID logo

1Department of Anesthesiology, Deyang People’s Hospital, Deyang, China; 2Shanghai Key Laboratory of Anesthesiology and Brain Functional Modulation, Translational Research Institute of Brain and Brain‑Like Intelligence, Clinical Research Center for Anesthesiology and Perioperative Medicine, Department of Anesthesiology and Perioperative Medicine, Shanghai Fourth People’s Hospital, School of Medicine, Tongji University, Shanghai, China

Contributions: (I) Conception and design: A Xie, R Zhou; (II) Administrative support: J Han, X Zhang; (III) Provision of study materials or patients: A Xie; (IV) Collection and assembly of data: A Xie; (V) Data analysis and interpretation: A Xie; (VI) Manuscript writing: All authors; (VII) Final approval of manuscript: All authors.

Correspondence to: An Xie, MD. Department of Anesthesiology, Deyang People’s Hospital, No. 173, Section 1 of North Taishan Road, Jingyang District, Deyang 618000, China. Email: 15802821332@163.com.

Background: Older patients are more likely to suffer from cardiopulmonary events during sedation-based bronchoscopy. It is important to balance the inhibition of stress and cardiopulmonary function, particularly for the elderly. This randomized controlled trial aims to investigate a fentanyl-reduced regimen on hypoxemia during bronchoscopy for older patients.

Methods: Eligible patients will be randomly allocated to the study group or control group. Medication regimen for the study group is remimazolam 0.2 mg/kg + esketamine 0.3 mg/kg + fentanyl 0.5 µg/kg, whereas those in the control group will receive remimazolam 0.2 mg/kg + fentanyl 1.5 µg/kg. Remimazolam 0.05 mg/kg will serve as top-ups for both groups. The primary outcome is the incidence of hypoxemia during bronchoscopy. The secondary outcomes include rates of successful examination, awakening time, discharge time, quality of recovery, satisfactory scores of patients and the endoscopist, incidences of hypotension or hypertension and body movement (cough, swing of the limbs, etc.).

Discussion: The present study aims to assess the effects of a fentanyl-reduced protocol on bronchoscopy for older patients. The results are supposed to be that the fentanyl-reduced regimen can provide sufficient sedation for geriatric bronchoscopy with fewer adverse events, which is worthy of clinical adoption.

Trial Registration: The trial has been registered at Chinese Clinical Trial Registry (ChiCTR2400084672).

Keywords: Esketamine; remimazolam; hypoxia; bronchoscopy; older patients

Submitted Mar 05, 2025. Accepted for publication May 22, 2025. Published online Jul 18, 2025.

doi: 10.21037/jtd-2025-475

Introduction

Bronchoscopy is widely used worldwide. It is an important means for the diagnosis and treatment of respiratory diseases, but it is also an invasive operation where patients may feel stressed and suffocated, and may suffer from a violent cough, laryngeal spasm, arrhythmia and even cardiac arrest (1-4). Thus, the procedure is usually performed under deep sedation or even general anesthesia. Due to the decline in respiratory and circulatory function, concomitant diseases and increased susceptibility to sedatives, older patients often face greater risks during fiberoptic bronchoscopy. Therefore, stable and effective anesthesia during fiberoptic bronchoscopy in the elderly has attracted much attention. Both the American College of Chest Physicians and the British Thoracic Society have proposed that topical anesthesia with lidocaine, sedation with propofol or benzodiazepines, and analgesia with opioids are the current consensus for fiberoptic bronchoscopy anesthesia (5,6). However, propofol and opioids often lead to the suppression of cardiovascular and respiratory systems, which adds extra risks for the elderly (7,8).

Remimazolam, a novel benzodiazepine sedative and short-acting γ-aminobutyric acid A (GABAA) receptor agonist, has been approved for sedation or anesthesia (9,10). In a prospective multicenter study, moderate sedation with remimazolam has been confirmed to be effective and safe for adults during bronchoscopy (11). In this study, remimazolam induced less hypotension and injection pain compared to propofol. Moreover, previous studies have demonstrated that remimazolam is safer than propofol for the elderly in gastrointestinal endoscopy (12,13). However, hypoxia and hypotension occur during the examination (14-16). This may be attributed to the concomitant use of opioids.

Esketamine, the dextrorotatory enantiomer of ketamine and a non-competitive N-methyl-D-aspartic acid (NMDA) receptor antagonist, is a commonly used anesthetic and analgesic. Owing to its strong analgesic effect, esketamine has been investigated as an opioid-free anesthesia (17,18). Moreover, the combination of esketamine and propofol is superior to remifentanil or fentanyl with propofol during bronchoscopy for adults (19,20). However, the incidence of choke is significantly higher without opioids (19). A sub-anesthetic dose of esketamine was successfully used as an adjuvant to propofol-remifentanil-induced anesthesia for pediatric bronchoscopy and was reported to reduce the cough scores (21).

Considering the particularity of bronchoscopy, endoscopists and anesthesiologists must manage a shared airway, which makes airway management difficult. During the examination, the bronchoscope partially obstructs the airway, and pulse oxygen saturation (SpO2) desaturation readily occurs during the operation, especially for the elderly (22). Thus, it is vital to achieve an optimal balance between sedation/analgesia and cardiopulmonary stability. In the present study, we hypothesized that a fentanyl-reduced regimen (combination of remimazolam, esketamine and fentanyl) could reduce the incidence of hypoxemia for geriatric patients undergoing bronchoscopy. We present this article in accordance with the SPIRIT reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-475/rc) (23).

Methods

Study overview

This study was designed as a single-center, randomized controlled trial. Flowchart of this study is shown in Figure 1 and trial schedule referring to the SPIRIT is displayed in Table 1. The study will be conducted in line with the Declaration of Helsinki and its subsequent amendments (24) at Deyang People’s Hospital, a tertiary hospital in Sichuan Province, China. The study (Protocol version 2.0) was approved by the Ethics Committee of Deyang People’s Hospital on 31 July 2023 (Protocol version 2.1; Document number 2023-03-011-K01) and was revised on 12 October 2024 (Document number 2023-03-011-K02). Written informed consent will be acquired from every participant before starting the study procedure. The study was registered at the Chinese Clinical Trial Registry (ChiCTR) under identifier ChiCTR2400084672.

Figure 1 Flowchart of this study.

Table 1

Trial schedule according to the SPIRIT recommendations

Time point Study period
Enrollment Allocation During bronchoscopy During recovery 1st post-examination day
Enrollment
   Eligibility screening X
   Informed consent X
   Allocation X
Interventions
   (I) Remimazolam 0.2 mg/kg + esketamine 0.3 mg/kg + fentanyl 0.5 μg/kg X
   (II) Remimazolam 0.2 mg/kg + fentanyl 1.5 μg/kg X
Assessments
   Basic variables X
   Incidence of hypoxia X
   Adverse events X
   Rate of successful examination X
   Awakening time X
   Discharge time X
   Satisfactory score X
   Quality of recovery X

SPIRIT, Standard Protocol Items: Recommendations for Interventional Trials.

Inclusion criteria

  • Patients who are going to undergo an elective bronchoscopy (endoscopic examination and alveolar washing) under sedation with an age between 65 and 85 years old;
  • The American Society of Anesthesiologists (ASA) classification is between grade I and grade III;
  • The body mass index (BMI) is between 18 and 28 kg/m2;
  • Patients who are able to understand the study process, communicate effectively with researchers and sign the written informed consent.

Exclusion criteria

  • Severe cardiovascular diseases, such as poorly controlled hypertension, coronary heart disease, chronic obstructive pulmonary disease and cardiopulmonary failure, etc.;
  • Difficult airway or hypoxemia before enrollment;
  • Head trauma or presence of central nervous system or psychiatric disorders;
  • Drug and/or alcohol abuse;
  • Allergic to the study drugs;
  • Glaucoma or increased intraocular pressure;
  • Severe hematological diseases;
  • Significant abnormality of liver and kidney function (the index is more than twice the normal value).

Recruitment plan

Considering the particularities of bronchoscopy under sedation, all patients must undergo a pre-anesthesia evaluation. So, the recruitment will be performed by the anesthesiologists during the pre-anesthesia evaluation. There will be a printed poster in the evaluation room. No additional recruitment advertisements will be distributed.

Randomization and blinding

An independent investigator will use SPSS 23.0 to generate random numbers and the numbers will be encoded as the study group and control group. A 1:1 allocation ratio will be maintained between the groups. The randomization scheme will be kept in sealed opaque envelopes by the randomization personnel. The envelopes will be opened in sequence of enrollment by the anesthesiologist who takes charge of the anesthesia procedure. Remimazolam (Yichang Humanwell Pharmaceuticals Co., Ltd., Yichang, China), esketamine (Jiangsu Hengrui Pharmaceuticals Co., Ltd., Lianyungang, China) and fentanyl (Yichang Humanwell Pharmaceuticals Co., Ltd.) will be prepared in the same injection syringes (10 mL) and labeled with small letters. Observational investigators assessing outcomes, patients and data analysts will be blinded to grouping.

Study procedure

All patients who need an elective bronchoscopy are required to have a pre-anesthesia evaluation. After a systematic evaluation, the investigators will introduce this study to eligible patients. If they agree to participate in the study, they will be enrolled after signing the informed consent.

All patients will be fasting for solids for 8 hours and fasting for liquids for 2 hours before examination. After entering the preparation room, the venous access of the upper limbs will be opened. The patients will be placed in the supine position upon entering the examination room, and blood pressure, electrocardiograph and SpO2 will be monitored. Oxygen will be supplied by a mask at a rate of 6 L/min. The anesthesia machine, laryngeal mask, and other rescue equipment and medicine will be on call. After pre-oxygenation, anesthesia induction will be initiated. The control group will be administered remimazolam 0.2 mg/kg intravenously 3 min before the start of bronchoscopy, and fentanyl 1.5 µg/kg 1 min later. The study group will be intravenously injected with remimazolam 0.2 mg/kg 3 min before the initiation of examination, and esketamine 0.3 mg/kg + fentanyl 0.5 µg/kg 1 min later. Process of anesthesia induction will be protected by an opaque screen, so that the observational investigator in the examination room cannot infer the group. Fiberoptic bronchoscopy will be performed by experienced bronchoscopists after the absence of eyelash reflex and body move. Lidocaine hydrochloride (2%) 5 mL will be locally sprayed through the bronchoscope biopsy port when entering the glottis, carina, and left and right main bronchus. The modified alertness/sedation score (MOAA/S) was used to assess sedation degree. Remimazolam 0.05 mg/kg will be added if body motion, cough, swallow or MOAA/S >2 occurs during the operation. When SpO2 is below 90%, jaw thrust maneuver will be performed. Manual ventilation will be further used for unimproved oxygenation. If it does not work, the endoscopist will withdraw the bronchoscope until SpO2 is stable above 95%. Vasoactive drugs will be applied to maintain the fluctuation of blood pressure within 20% of the baseline.

After the examination, patients will be transferred to the post-anesthesia care unit (PACU) accompanied by the observational investigator. Recovery procedure will be in accordance with standard care practice. When the Steward score (25) reaches more than 4 points, patients are allowed to leave. The Quality of Recovery-15 rating scale (QoR-15) (26) will be collected via visit or phone call on the 1st post-examination day.

When there are severe complications, anesthesia accidents, or other circumstances that the endoscopist or the investigators deem it inappropriate to proceed, the cases will be stopped, documented and reported to the officials. Consequently, the blinding will be abolished. Study-related adverse events will be treated free of charge.

Outcomes

Basic data

Demographic data, such as the age, sex, body mass, height, BMI, baseline SpO2 and ASA status, will be recorded during eligibility evaluation. Intraoperative data, such as SpO2 value after pre-oxygenation, the duration of bronchoscopy, the type of bronchoscopy, the times of top-ups and the dosage of drugs, will be documented by the observational investigator.

Primary outcome

The primary outcome of this study is the incidence of hypoxia during sedation. Hypoxia is defined as SpO2 <90%.

Secondary outcomes

The times of jaw thrust maneuver and manual ventilation;

  • Rate of successful examination. Success is defined as that the examination is not abandoned due to sedation;
  • Awakening time: the time from the last dose of anesthetics to the time when the patient can respond to open eyes;
  • Discharge time: the time from awakening to meeting the discharge criteria (Steward score >4);
  • Quality of recovery: the scores of QoR-15 rating scale;
  • Satisfactory scores of patients and the endoscopist: 0 to 10 points (extremely unsatisfactory to extremely satisfactory);
  • Adverse events during sedation and post-anesthesia recovery: incidence of hypotension or hypertension (defined as the change of blood pressure >20% of baseline); incidence of body movement (cough, swing of the limbs, etc.); incidence of laryngospasm; the degree of salivation:
    • Grade 0: the oral mucosa is dry and no saliva can be seen;
    • Grade 1: the mucosa is slightly moist and there is no accumulation of saliva;
    • Level 2: obvious saliva accumulation, requiring intermittent aspiration;
    • Level 3: a large amount of saliva gushes out and requires frequent suction.

Sample size calculation

The sample size was based on the incidence of intraoperative hypoxemia of the pilot study. In our pilot study, the incidence of intraoperative hypoxia was 30% in the control group and 15% in the study group. Given a two-side α of 0.05, a power level of 0.85, the sample size ratio of 1:1, and a 10% dropout rate, 148 individuals should be recruited in each group. The calculation was performed by an independent investigator using SPSS 23.0.

Statistical analyses

Statistical analyses will be performed using SPSS 23.0. All case report forms will be collected by two independent investigators who do not participate in data analysis. The data will be logged into Excel by the two data keepers in a double-check mode. Private information including name and medical record number will not be included into the database. Data access will be kept by the Department of Technology of our institution.

Firstly, the parameters will be divided into two categories: quantitative data and qualitative data. Normality will be applied to quantitative data by Kolmogorov-Smirnov test. Normal data will be presented as mean ± standard deviation and analyzed using the Student’s t-test. Non-normal data will be shown as median (25th percentile, 75th percentile) and analyzed using the Wilcoxon rank-sum test. The Fisher’s exact test or chi-square test will be used to analyze qualitative data which will be presented as number and percentage. The significance level is 0.05.

Patients who do not finish the examination due to various reasons will not be included into the final analyses. Sensitivity analysis will be employed to analyze QoR-15 if there are dropout cases.

Discussion

According to the world population report, the proportion of the elderly (≥65 years old) is estimated to rise from 10% in 2022 to 16% in 2050 (27). This means that an increasing number of older adults may undergo a bronchoscopy for the diagnosis and treatment of respiratory diseases. Therefore, safety and risk management of bronchoscopy for the elderly should be paid much more attention.

Opioid-free strategies have been reported in intraoperative analgesia, postoperative analgesia, gastrointestinal endoscopy and bronchoscopy (19,28-30). In the study conducted by Nie et al. (19), esketamine 0.2 mg/kg was used in bronchoscopy and was considered to have advantages over remifentanil 0.5 µg/kg when combined with propofol. However, when we used this protocol, some patients experienced persistent coughing even though performed with lidocaine anesthesia. Since the stimulation of bronchoscopy is intensive, opioids are effective to inhibit the stress and are recommended by most of the guidelines (6,31,32). Therefore, we tried an opioid-reduced rather than an opioid-free project, which is in line with the British Thoracic Society recommendation (6).

The present study aims to assess the effects of a fentanyl-reduced protocol on bronchoscopy for older patients. Owing to the efficiency and safety of remimazolam and esketamine, and less suppression on cardiopulmonary system (7,12,20,21), this fentanyl-reduced protocol is consisted of remimazolam, esketamine and a low dose of fentanyl. We will evaluate the efficiency and safety, especially the suppression of respiratory function. The results are supposed to provide a novel option for gerontic bronchoscopy. However, as a single-center study, the results may have limited generalizability. Future multi-center validation will be performed if it is worth promotion.

Acknowledgments

We appreciate support from the Endoscopy Center of Deyang People’s Hospital.

Footnote

Reporting Checklist: The authors have completed the SPIRIT reporting checklist. Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-475/rc

Peer Review File: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-475/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-475/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study will be conducted in line with the Declaration of Helsinki and its subsequent amendments at Deyang People’s Hospital, a tertiary hospital in Sichuan Province, China. The study (Protocol version 2.0) was approved by the Ethics Committee of Deyang People’s Hospital on 31 July 2023 (Protocol version 2.1; Document number 2023-03-011-K01) and was revised on 12 October 2024 (Document number 2023-03-011-K02). Written informed consent will be acquired from every participant before starting the study procedure.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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Cite this article as: Xie A, Zhang X, Han J, Zhou R. Effects of non-intubation anesthesia based on a fentanyl-reduced regimen on hypoxemia during bronchoscopy for older patients: study protocol for a randomized controlled trial. J Thorac Dis 2025;17(7):5388-5395. doi: 10.21037/jtd-2025-475

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