Skip to main content

Dexmedetomidine versus propofol sedation in flexible bronchoscopy: a randomized controlled trial

Abstract

Background

Dexmedetomidine (DEX), is a highly selective alpha2 adrenoceptor (α2-AR) agonist, successfully used in various procedures including flexible bronchoscopy. Randomized controlled trials (RCTs) evaluating DEX sedation during bronchoscopy report equivocal results regarding respiratory and hemodynamic outcomes.

Methods

We conducted an RCT to evaluate the efficacy and safety of dexmedetomidine compared to propofol for sedation during bronchoscopy. The primary outcome was the number of desaturation events, secondary outcomes were transcutaneous Pco2 level, hemodynamic adverse events and physician and patient satisfaction.

Results

Overall, 63 patients were included, 30 and 33 in the DEX and propofol groups, respectively. The number of desaturation events was similar between groups, median (IQR) 1 (0–1) and 1 (0–2) in the DEX and control groups, respectively (P = 0.29). Median desaturation time was 1 (0–2) and 1 (0–3) minutes in the DEX and control groups, respectively (P = 0.48). Adverse events included hypotension, 33% vs 21.1% in intervention and control groups, respectively (P = 0.04), bradycardia, cough, and delayed recovery from sedation. Total adverse events were 22 and 7 in DEX and propofol groups, respectively (P = 0.009).

Conclusion

Dexmedetomidine sedation during bronchoscopy did not show differences in oxygen saturation and transcutaneous CO2 level in comparison to propofol. Moreover, DEX sedation required a significantly higher number of rescue boluses, due to inadequate sedation and was associated with a higher rate of adverse events.

Trial registration NCT04211298, registration date: 26.12.2019.

Peer Review reports

Background

Fiberoptic bronchoscopy (FOB) is commonly used for the diagnosis and management of a variety of lung diseases [1, 2]. The procedure is usually performed under sedation, with a selection of available methods to provide different depths and lengths of sedation, according to the type of procedure and operator preference [3, 4]. Dexmedetomidine (DEX) is a highly selective alpha2 adrenoceptor (α2-AR) agonist, it has sedative, anxiolytic and analgesic qualities. Following intravenous administration, DEX has a distribution half-life of six minutes and a terminal elimination half-life (t½) of approximately two hours. Reported adverse events include both hypotension and hypertension, bradycardia, dry mouth and nausea [5, 6]. DEX has been successfully used in a wide array of procedures including colonoscopy, endoscopic retrograde cholangio-pancreatography (ERCP), laparoscopic procedures, shockwave lithotripsy, awake carotid endarterectomy, retinal surgery and in pediatric patients [7,8,9,10,11,12,13,14,15]. In 2012 Ryu et al. conducted the first randomized controlled trial (RCT) that evaluated the use of DEX during bronchoscopy. The DEX group had a significantly lower rate of desaturation events, with no between group difference in level of sedation, oxygen saturation, mean arterial pressure and heart rate [16]. During the period from 2012 to 2021 eleven more RCTs were conducted to evaluate DEX during bronchoscopy, in comparison to propofol, midazolam and fentanyl, in various combinations. While some of these trials reported a lower rate of desaturation events and an adequate sedation level, others reported no difference in desaturation events, a higher rate of hemodynamic adverse events and an inferior level of patient sedation and bronchoscopist satisfaction [17,18,19,20,21,22,23,24,25,26,27]. Therefore, DEX sedation for bronchoscopy is considered an emerging method for sedation during bronchoscopy. However, whether DEX sedation conveys a lower rate of desaturation events or adequate sedation level is yet to be determined. In this study we conducted an RCT to evaluate the efficacy and safety of dexmedetomidine sedation in comparison to propofol sedation during bronchoscopy.

Methods

We conducted a single center, RCT, that compared the use of dexmedetomidine to propofol, as the main drug for sedation during bronchoscopy. Patients were recruited between December 2019 to April 2020 and from January to May 2021. During these time intervals adult patients (age > 18 years) who were scheduled to undergo Bronchoscopy at Rabin Medical Center (RMC) in Israel, were offered to participate in the study. Exclusion criteria included: known or suspected allergy to any of the study drugs, seizure disorder, renal impairment (with serum creatinine > 2 mg/dL) or hepatic impairment (elevated liver enzymes > 2 times normal levels), hemodynamic instability (bradycardia with HR < 50 bpm or hypotension with SBP < 90 mmHg), or seriously ill patients with American Society of Anesthesiologists’ (ASA) physical status above III. The study was approved by RMC institutional review board (IRB) (RMC-0312-19) and registered in a clinical trial registry (NCT04211298, registration date: 26.12.2019). All methods were carried out in accordance with the CONSORT guidelines and regulations. After signing an informed consent form, the patient was randomized with computer generated random numbers, sealed in opaque envelopes, to either DEX group or propofol group.

Sedation protocol

An anesthesiologist was present throughout each procedure and oversaw monitoring and sedation protocol in all cases, a pulmonologist and a nurse were also present in all procedures. The number of procedures each day was between 3 to 4. Monitoring included continuous electrocardiography, pulse oximetry, transcutaneous PCO2 and automated noninvasive blood pressure recordings. All patients received supplemental nasal oxygen at 2–5 l/min. The port of entry was usually nasal, laryngeal mask airway (LMA) was used in endobronchial ultrasonography (EBUS) procedures. Rigid bronchoscopy was not used in this study. The sedation protocols for both groups included a loading dose of fentanyl 1 mcg/kg and midazolam 1 mg. Patients randomized to the DEX group received a loading dose of 1 mcg/kg over 15 min followed by a continuous intravenous infusion at a rate of 0.5 mcg/kg/h. Patients in the propofol group received a dose of 0.5–1 mg/kg for induction over 1 min followed by a maintenance infusion in a dose of 100–200 mcg/kg/min. In both groups bolus doses of propofol of 0.1–0.5 mg/kg were given for insufficient sedation. Topical anesthesia on the vocal cord and carina, with 1% lidocaine, was used in all patients.

Outcomes

The primary outcomes were the number of de-saturation events, during bronchoscopy and the time in which the oxygen saturation level decreased under 90%. Secondary outcomes were the Richmond Agitation Sedation Scale (RASS), level of transcutaneous PCO2 (PcCO2), blood pressure, number of propofol boluses given for insufficient sedation, length of procedure and adverse events. Bronchoscopist satisfaction level and patient discomfort were also evaluated on a scale of 1 to 5. For physician satisfaction 5 represents high satisfaction and 1 poor satisfaction. For patient discomfort 5 represents no discomfort and 1 maximal discomfort.

Statistical analysis

The baseline characteristics and secondary outcomes were analyzed with the student’s t-test, chi-square test and the Mann–Whitney U test, as appropriate. The primary outcome was analyzed with the chi-square test for the number of desaturation events and with the Mann–Whitney U test for the time in which desaturation was recorded. A P-value of 0.05 was considered as significant. Statistical analysis was conducted with the SPSS version 27 software. Sample size was calculated with WINPEPI software, the primary outcome evaluated was the number of desaturation events per patient. Assuming a variance of 1.5 events and to detect a mean difference of 1 event with an alpha of 0.05 and a power of 80%, a sample size of 48 patients (24 in each group) is required.

Results

Overall, 63 patients were included in the current study, 30 patients in the DEX group and 33 in the propofol group. Mean age in the intervention and control groups was 58.76 ± 15.09 and 62.96 ± 9.69, respectively (P = 0.19). Weight, ASA score and baseline CO2 were similar between groups. Male sex was more common in the propofol group, 69% vs 43% in the control and intervention groups, respectively (P = 0.03). Three patients in the propofol group were chronically treated with neuro-psychiatric medication in comparison to zero patients in the DEX group (P = 0.16). There was no difference in the distribution of COPD, IHD, CHF between treatment groups. Procedure types were balanced between groups (Table 1). The number of desaturation events was similar between groups, median (IQR) 1 (0–1) and 1 (0–2) in the intervention and control groups, respectively (P = 0.29). The median desaturation time was 1 (0–2) and 1 (0–3) minutes in the intervention and control groups respectively (P = 0.48). The median rise in PcCO2 was 18.45 (14.70–22.97) and 20.65 (15.37–30.07) mm/Hg and the median time in which PcCO2 was above 50 mm/Hg was 17.5 (14.12–27.12) and 19.5 (7.75–29.75) minutes in the intervention and control groups, respectively (P = 0.46 and P = 0.94). The median RASS score was − 2 [(− 3) to (− 2)] and − 3 [(− 3) to (− 2)] for the DEX and propofol groups, respectively (P = 0.01). Patients in the DEX group required a median of 2.5 (2–5) propofol rescue boluses during the procedure in comparison to 2 (1.0–2.5) boluses in the propofol group (P = 0.01), the median of total propofol dose of additional rescue boluses was 90 mg (50–109) and 58 mg (42–106.5) in the DEX and propofol groups, respectively (P = 0.18). Median procedure time was 20 (8–35) and 21 (15–27.5) minutes in the intervention and control groups, respectively (P = 0.70). Adverse events included hypotension, 33% vs 21.1% in the intervention and control groups, respectively (P = 0.04), post-procedural hypotension, bradycardia, cough and delayed recovery from sedation. The total number of adverse events was 22 in the DEX group and 7 in the propofol group (P = 0.009) (Table 2). The median score of physician satisfaction from sedation during procedure was 4.5 (4–5) and 5 (5–5) and the median score of patient discomfort was 5 (4.5–5) and 5 (5–5) in the intervention and control groups, respectively (P = 0.01 and P = 0.1).

Table 1 Demographic and baseline clinical characteristics
Table 2 Clinical outcomes for the intervention (dexmedetomidine) and control (propofol) groups

Discussion

In this study we have evaluated dexmedetomidine sedation during bronchoscopy and whether its mechanism of action, which does not involve central respiratory drive depression, has a favorable effect on the respiratory and hemodynamic adverse events. The results showed, that in comparison to propofol sedation, there was no difference in oxygen saturation, both in the number of desaturation events and in the total desaturation time (in which the oxygen saturation was lower than 90%). The level of CO2 was also similar between treatment groups, there was no difference in the median rise in PcCO2 during procedure and in the total time period in which the PcCO2 level was above 50 mm/Hg. The DEX group however, showed inferior performance in the adequacy of sedation, with a significantly higher RASS score and a significantly higher number of propofol rescue boluses during the procedure. Moreover, use of DEX was associated with a significantly higher frequency of hypotension events and total adverse events. Finally, the level of physician satisfaction was significantly lower in the DEX group.

A review of the literature shows 12 published RCT’s that evaluated DEX sedation for bronchoscopy [16,17,18,19,20,21,22,23,24,25,26,27]. Four trials evaluated DEX for conscious sedation and administered the drug only once at the beginning of the procedure [17, 23, 25, 26]. The largest of these trials by Zhang et al. reported a lower rate of desaturation events in the DEX group however, with a higher rate of adverse events, correspondingly to the current trial. One trial evaluated DEX for general anesthesia and the other 7 trials evaluated DEX for moderate/deep sedation, of these, five reported no difference in the rate of desaturation events, correspondingly to the current trial. While two trials reported a significantly lower rate of desaturation events with DEX [16, 20] (Table 3). The reported rate of adverse events varies between trials, some report a higher rate with DEX, as seen in the current trial, while some report lower rates. These inconsistences between trials can be explained by different dosing, additional drugs used for sedation, different comparators, and types of procedures. In the current trial we used midazolam and fentanyl for induction and propofol rescue boluses in both arms. The use of additional drugs can introduce potential confounding factors, (e.g., paradoxical agitation with benzodiazepine and respiratory drive depression, due to fentanyl and propofol use). Nonetheless, these confounding factors would not likely significantly impact the results regarding respiratory outcomes or have increased the rate of adverse events. Additional outcomes evaluated in the current study, included the level of sedation obtained and bronchoscopist satisfaction. For these we found DEX was inferior to propofol. Conversely, most other similar trials reported no difference in the level of sedation, apart from one trial that reported superior sedation with DEX in comparison to midazolam [19,20,21,22].

Table 3 Literature review—randomized controlled trials who evaluated dexmedetomidine sedation in flexible bronchoscopy procedures

The current combined evidence cannot afford us to ascertain whether DEX sedation is superior to other sedation regimens used during bronchoscopy. Nonetheless, this trial contributes to the growing body of evidence, together with a group of small RCTs, albeit demonstrating inconclusive results regarding DEX sedation during bronchoscopy. Additional large RCT’s are warranted to characterize the groups of patients and types of procedures that will confer the most benefit from DEX sedation. Moreover, since Dexmedetomidine is intended to assist in patients with high respiratory risk, it should also be evaluated with noninvasive respiratory assistance, such as high flow nasal cannula and CPAP/BiPAP devices [28, 29].

The main limitations of this study are its small sample size, lack of blinding, the use of additional drugs for sedation and inclusion of heterogenous types of procedures. However, all procedures were done with moderate sedation and although additional drugs for sedation were used, the sedation regimen and dosing were identical in all patients.

In conclusion, DEX sedation during bronchoscopy did not show differences in oxygen saturation and transcutaneous CO2 level in comparison to propofol. Moreover, DEX sedation required a significantly higher number of rescue boluses, due to inadequate sedation and was associated with a higher rate of adverse events.

Availability of data and materials

The datasets used and/or analyzed during the current study available from the corresponding author on reasonable request.

Abbreviations

DEX:

Dexmedetomidine

RCT:

Randomized controlled trials

IQR:

Inter quartile range

CI:

Confidence interval

FOB:

Fiberoptic bronchoscopy

ERCP:

Endoscopic retrograde cholangio-pancreatography

RMC:

Rabin medical center

IRB:

Institutional review board

PcCO2:

Transcutaneous carbon dioxide partial pressure

COPD:

Chronic obstructive pulmonary disease

IHD:

Ischemic heart disease

CHF:

Chronic heart failure

CPAP:

Continuous positive airway pressure

BiPAP:

Bilevel positive airway pressure

References

  1. Du Rand IA, Blaikley J, Booton R, Chaudhuri N, Gupta V, Khalid S, et al. Summary of the British Thoracic Society guideline for diagnostic flexible bronchoscopy in adults. Thorax. 2013;68(8):786–7.

    Article  Google Scholar 

  2. American Thoracic Society. Medical Section of the American Lung Association. Position paper on guidelines for fiberoptic bronchoscopy in adults. Am Rev Respir Dis. 1987;136(4):1066.

    Article  Google Scholar 

  3. Sarkiss M. Anesthesia for bronchoscopy and interventional pulmonology: from moderate sedation to jet ventilation. Curr Opin Pulm Med. 2011;17(4):274–8.

    Article  Google Scholar 

  4. Goudra BG, Singh PM, Borle A, Farid N, Harris K. Anesthesia for advanced bronchoscopic procedures: state-of-the-art review. Lung. 2015;193(4):453–65.

    Article  CAS  Google Scholar 

  5. Barends CRM, Absalom A, van Minnen B, Vissink A, Visser A. Dexmedetomidine versus Midazolam in procedural sedation. A systematic review of efficacy and safety. PLoS ONE. 2017;12(1):e0169525.

    Article  Google Scholar 

  6. Naaz S, Ozair E. Dexmedetomidine in current anaesthesia practice—a review. J Clin Diagn Res JCDR. 2014;8(10):GE01-04.

    PubMed  Google Scholar 

  7. Goyal R, Hasnain S, Mittal S, Shreevastava S. A randomized, controlled trial to compare the efficacy and safety profile of a dexmedetomidine-ketamine combination with a propofol-fentanyl combination for ERCP. Gastrointest Endosc. 2016;83(5):928–33.

    Article  Google Scholar 

  8. Eberl S, Preckel B, Bergman JJ, van Dieren S, Hollmann MW. Satisfaction and safety using dexmedetomidine or propofol sedation during endoscopic oesophageal procedures: a randomised controlled trial. Eur J Anaesthesiol. 2016;33(9):631–7.

    Article  CAS  Google Scholar 

  9. Zhang X-K, Chen Q-H, Wang W-X, Hu Q. Evaluation of dexmedetomidine in combination with sufentanil or butorphanol for postoperative analgesia in patients undergoing laparoscopic resection of gastrointestinal tumors: a quasi-experimental trial. Medicine (Baltimore). 2016;95(50):e5604.

    Article  CAS  Google Scholar 

  10. Lu Z, Li W, Chen H, Qian Y. Efficacy of a Dexmedetomidine-Remifentanil combination compared with a Midazolam-Remifentanil combination for conscious sedation during therapeutic endoscopic retrograde cholangio-pancreatography: a prospective, randomized, single-blinded preliminary trial. Dig Dis Sci. 2018;63(6):1633–40.

    Article  CAS  Google Scholar 

  11. Kinugasa H, Higashi R, Miyahara K, Moritou Y, Hirao K, Ogawa T, et al. Dexmedetomidine for conscious sedation with colorectal endoscopic submucosal dissection: a prospective double-blind randomized controlled study. Clin Transl Gastroenterol. 2018;9(7):167.

    Article  Google Scholar 

  12. Ghali A, Mahfouz AK, Ihanamäki T, El Btarny AM. Dexmedetomidine versus propofol for sedation in patients undergoing vitreoretinal surgery under sub-Tenon’s anesthesia. Saudi J Anaesth. 2011;5(1):36–41.

    Article  Google Scholar 

  13. Jalowiecki P, Rudner R, Gonciarz M, Kawecki P, Petelenz M, Dziurdzik P. Sole use of dexmedetomidine has limited utility for conscious sedation during outpatient colonoscopy. Anesthesiology. 2005;103(2):269–73.

    Article  CAS  Google Scholar 

  14. Cooper L, Candiotti K, Gallagher C, Grenier E, Arheart KL, Barron ME. A randomized, controlled trial on dexmedetomidine for providing adequate sedation and hemodynamic control for awake, diagnostic transesophageal echocardiography. J Cardiothorac Vasc Anesth. 2011;25(2):233–7.

    Article  CAS  Google Scholar 

  15. Kaygusuz K, Gokce G, Gursoy S, Ayan S, Mimaroglu C, Gultekin Y. A comparison of sedation with dexmedetomidine or propofol during shockwave lithotripsy: a randomized controlled trial. Anesth Analg. 2008;106(1):114–9.

    Article  CAS  Google Scholar 

  16. Ryu JH, Lee SW, Lee JH, Lee EH, Do SH, Kim CS. Randomized double-blind study of remifentanil and dexmedetomidine for flexible bronchoscopy. Br J Anaesth. 2012;108(3):503–11.

    Article  CAS  Google Scholar 

  17. Zhang Q, Zhou J, He Q, Guan S, Qiu H, Xu X, et al. Dexmedetomidine combined with midazolam infusion guided by bispectral index during bronchoscopy. Clin Respir J. 2021. https://doi.org/10.1111/crj.13383.

    Article  PubMed  PubMed Central  Google Scholar 

  18. Yuan F, Fu H, Yang P, Sun K, Wu S, Lv M, et al. Dexmedetomidine-fentanyl versus propofol-fentanyl in flexible bronchoscopy: a randomized study. Exp Ther Med. 2016;12(1):506–12.

    Article  CAS  Google Scholar 

  19. Lin T-Y, Huang Y-C, Kuo C-H, Chung F-T, Lin Y-T, Wang T-Y, et al. Dexmedetomidine sedation for endobronchial ultrasound-guided transbronchial needle aspiration, a randomised controlled trial. ERJ Open Res. 2020. https://doi.org/10.1183/23120541.00064-2020.

    Article  PubMed  PubMed Central  Google Scholar 

  20. St-Pierre P, Tanoubi I, Verdonck O, Fortier L-P, Richebé P, Côté I, et al. Dexmedetomidine versus Remifentanil for monitored anesthesia care during endobronchial ultrasound-guided transbronchial needle aspiration: a randomized controlled trial. Anesth Analg. 2019;128(1):98–106.

    Article  CAS  Google Scholar 

  21. Kumari R, Jain K, Agarwal R, Dhooria S, Sehgal IS, Aggarwal AN. Fixed dexmedetomidine infusion versus fixed-dose midazolam bolus as primary sedative for maintaining intra-procedural sedation during endobronchial ultrasound-guided transbronchial needle aspiration: a double blind randomized controlled trial. Expert Rev Respir Med. 2021;15:1597–604.

    Article  CAS  Google Scholar 

  22. Kim J, Choi SM, Park YS, Lee C-H, Lee S-M, Yoo C-G, et al. Dexmedetomidine versus midazolam for sedation during endobronchial ultrasound-guided transbronchial needle aspiration: a randomised controlled trial. Eur J Anaesthesiol. 2021;38(5):534–40.

    Article  CAS  Google Scholar 

  23. Magazine R, Venkatachala SK, Goneppanavar U, Surendra VU, Guddattu V, Chogtu B. Comparison of midazolam and low-dose dexmedetomidine in flexible bronchoscopy: a prospective, randomized, double-blinded study. Indian J Pharmacol. 2020;52(1):23–30.

    Article  CAS  Google Scholar 

  24. Li H, Zhang N, Zhang K, Wei Y. Observation of the clinical efficacy of dexmedetomidine in flexible bronchoscopy under general anesthesia: clinical case experience exchange. J Int Med Res. 2019;47(12):6215–22.

    Article  Google Scholar 

  25. Riachy M, Khayat G, Ibrahim I, Aoun Z, Dabar G, Bazarbachi T, et al. A randomized double-blind controlled trial comparing three sedation regimens during flexible bronchoscopy: dexmedetomidine, alfentanil and lidocaine. Clin Respir J. 2018;12(4):1407–15.

    Article  CAS  Google Scholar 

  26. Goneppanavar U, Magazine R, Periyadka Janardhana B, Krishna Achar S. Intravenous dexmedetomidine provides superior patient comfort and tolerance compared to intravenous Midazolam in patients undergoing flexible bronchoscopy. Pulm Med. 2015;2015:727530.

    Article  Google Scholar 

  27. Liao W, Ma G, Su QG, Fang Y, Gu BC, Zou XM. Dexmedetomidine versus midazolam for conscious sedation in postoperative patients undergoing flexible bronchoscopy: a randomized study. J Int Med Res. 2012;40(4):1371–80.

    Article  CAS  Google Scholar 

  28. Korkmaz Ekren P, Basarik Aydogan B, Gurgun A, Tasbakan MS, Bacakoglu F, Nava S. Can fiberoptic bronchoscopy be applied to critically ill patients treated with noninvasive ventilation for acute respiratory distress syndrome? Prospective observational study. BMC Pulm Med. 2016;16(1):89.

    Article  Google Scholar 

  29. Combe BL, Messika J, Labbé V, Razazi K, Maitre B, Sztrymf B, et al. High-flow nasal oxygen for bronchoalveolar lavage in acute respiratory failure patients. Eur Respir J. 2016;47(4):1283–6.

    Article  Google Scholar 

Download references

Acknowledgements

The authors express their gratitude to Ms. Dalia Dawn Orkin for her English language editing services.

Funding

None.

Author information

Authors and Affiliations

Authors

Contributions

BP, BK, SK and KA collected the data, MRK, DR and BP performed the procedures, SI and BP performed the statistical analysis and wrote the manuscript. MRK, DR and YS revised the manuscript. All authors read and approved the final manuscript.

Corresponding author

Correspondence to Barak Pertzov.

Ethics declarations

Ethics approval and consent to participate

Subjects have given their written informed consent. The study protocol has been approved by the institutes’ Ethical Review Board (RMC-0312-19). The study protocol was registered in a clinical trial registry (NCT04211298, registration date:26/12/2019). https://clinicaltrials.gov/ct2/show/NCT04211298.

Consent for publication

Not applicable.

Competing interests

The authors have no competing interests to declare.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Pertzov, B., Krasulya, B., Azem, K. et al. Dexmedetomidine versus propofol sedation in flexible bronchoscopy: a randomized controlled trial. BMC Pulm Med 22, 87 (2022). https://doi.org/10.1186/s12890-022-01880-9

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: https://doi.org/10.1186/s12890-022-01880-9

Keywords