Abstract

Background

Nasotracheal intubation (NTI) is frequently used during oral and maxillofacial surgeries [1].Various complications, especially epistaxis and damage to the airway, can occur during NTI [2]. Fiberoptic bronchoscopy-guided NTI is associated with less epistaxis and better navigability and has a lower redirection rate [3].In other studies, compared with the Macintosh laryngoscope, fiberoptic bronchoscopy-guide NTI resulted in a lower rate of sore throat and significantly shortened the total intubation time and the McGrath MAC laryngoscope improved the field of view during intubation and shortened the intubation time [4, 5].

The Disposcope endoscope (Dexscope^TM, Yangzhou Dex Medical Device Co., Ltd., Yangzhou, China) is a medical device used for endotracheal intubation. Its wire tube body is made of flexible memory metal and can be bent easily during surgery; this enables doctors to adjust it to the optimum angle for each patient and situation (Fig. 1, A and B). Compared to the Macintosh laryngoscope, the Disposcope endoscope has a higher success rate in endotracheal intubation and provides a better view of the glottis; it also has a shorter intubation time and causes fewer dental injuries when used to imitate intubation on a manikin wearing a semi-rigid neck collar [6]. In trauma patients wearing a semi-rigid neck collar, the Disposcope endoscope demonstrated a promising ability to guide successful endotracheal intubation [6]. Another study showed that the Disposcope endoscope could also be applied successfully in double-lumen tube placement [7].

In line with previous findings, our pilot study shows the Disposcope endoscope-guided NTI is convenient and effective. We hypothesized that the Disposcope endoscope would be as effective as fiberoptic bronchoscopy in guiding NTI.

Methods

In a pilot study (10 patients in total), the time to complete NTI (NTI time) was significantly longer in the fiberoptic group than in the Disposcope group (43.0 ± 13.4 s vs 24.0 ± 3.2 s). To achieve 95 % power of the test and a α-error of 5 %, the total sample size was 8 patients per group using G*Power 3.1.9.4 software. Sixty adult patients rated American Society of Anaesthesiologists (ASA) I and II who were scheduled to undergo elective oral and maxillofacial surgery requiring NTI under general anaesthesia were selected. We excluded patients from our study if he or she fell into any of the following categories: (1) younger than 18 years old or older than 80 years old; (2) body mass index (BMI) ≥ 30 kg/m²; (3) preoperative Mallampati score of III or higher; (4) a history of nasal abnormality (e.g., nasal trauma, surgery, obstruction, and polyps); (5) undergoing anticoagulation therapy; (6) an oral malignant tumour or difficulty anticipated in airway management; (7) diagnosed as having a mental disorder; and (8) presented with activity in the cervical vertebra. None of the patients were premedicated, and standard monitoring equipment was used in the operating room. All study subjects were randomized by a research blinding to the study with an envelope containing the randomization number an group information to the following two groups (n = 30 per group) to determine the airway device that would be used to guide NTI: the fiberoptic bronchoscopy-guided group (fiberoptic group) or the Disposcope endoscope-guided group (Disposcope group).

General anaesthesia was induced with 1.5-2 mg/kg intravenous propofol and 0.3 μg/kg sufentanil, and muscle relaxation was achieved by intravenous administration of 0.15 mg/kg cisatracurium. Size and patency were estimated by fiberoptic bronchoscopy (Pentax FI-10BS, Pentax Corporation, Tokyo, Japan) in each nostril. Before intubation, manual ventilation was performed with 100 % oxygen via a facemask for 3 minutes. Five drops of 1 % ephedrine solution were instilled into the larger nasal cavities to prevent bleeding. Males and females were intubated with 6.5-mm and 6.0-mm wire-reinforced tracheal tubes, respectively (TUORen Medical Equipment Co., Henan, China) with high-volume, low-pressure cuffs. Anaesthesia was maintained with propofol and remifentanil at a rate of 0.1-0.15 mg/kg/min and 0.1-0.2 μg/kg/min, respectively.

In the fiberoptic group, intubation was performed with the one-hand manoeuvre [8]. In the Disposcope group, the depth of the wire transfer that was lubricated with aseptic liquid paraffin for insertion was pre-measured to ensure that its tip of did not exceed the tube before NTI, and the shape of the wire transfer was curved by the operator before NTI. Then, an aseptic suction catheter (OD, 5.33 mm, TUORen Medical Equipment Co., Henan, China) lubricated with aseptic liquid paraffin was inserted through the tracheal tube (Fig. 1, C and D). The tip of the catheter was directed ventrally, and the tracheal tube was then advanced through the nasopharynx until the placed-depth arrived at 15 cm. The suction catheter was withdrawn after the steps above were completed. Then, the operator used the thumb and index finger of one hand to lift the mandible during the intubation [6]. The whole process flowed as shown above Fig. 2 (A-F). All intubations were performed by an anaesthesiologist who was familiar with both techniques and had 15 years of experience and a trained assistant. Minute adjustments in ventilation were performed to keep end-tidal CO₂ pressures at 35 - 45 mmHg after intubation.

The NTI time, which was defined as the time from when the fiberoptic bronchoscope or aseptic suction catheter was inserted into the nasal cavity to the time at which the tracheal tube was correctly inserted through the glottis, was recorded.

Epistaxis was recorded by an investigator blinded to group assignment using direct laryngoscopy five minutes after completing NTI and was scored as one of four grades according to the following modified criteria: no epistaxis (no blood observed on either the surface of the tube or the posterior pharyngeal wall); mild epistaxis (blood apparent on the surface of the tube or posterior pharyngeal wall); moderate epistaxis (pooling of blood on the posterior pharyngeal wall); and severe epistaxis (a large amount of blood in the pharynx impeding nasotracheal intubation and necessitating urgent orotracheal intubation) [9].

Each patient received 0.1 μg/kg sufentanil intravenously for postoperative analgesia upon the completion of the operation. Neuromuscular blockade was reversed using neostigmine (1 mg) and atropine (0.5 mg), and the trachea was extubated when the patient was awake. At 15 minutes, 1 h and 24 h after extubation, the patients were asked to rate their nasal pain on a visual analogue scale (VAS) according to a 10-cm vertical score ranging from 0 = no pain to 10 = worst pain imaginable by an independent anaesthetist who was unaware of which method had been used for NTI.

The study protocol was reviewed and approved by the Institutional Research Ethics Committee of The First People’s Hospital of Hefei (No. 2016-6) on 3 March 2016. The study was also registered in the Chinese Clinical Trial Registry (www.chictr.org.cn, ChiCTR-IPR-17011462). Informed written consent was obtained from all patients in this study, and that this study was conducted in accordance with the Declaration of Helsinki.

Data are expressed as the mean (SD). Parametric data were compared between groups by analysis of variance and post hoc testing. The mean difference and the 95% confidence interval (CI) of the mean difference were calculated. Categorical data were analyzed using Fisher’s exact test.The relative risks of the proportion of categorical data and 95% CI were calculated. Statistical significance was assumed if P values of < 0.05. All statistical analyses were performed with the Statistical Package for Social Sciences (SPSS) software 13.0.

Results

Sixty patients consented to participate in the study. Fig. 3 shows the CONSORT flow diagram for patient inclusion. There were no significant differences between the groups in patient age, height, weight, BMI, ASA scores, or Mallampati scores or the sex ratio or duration of tracheal tube indwelling time (Table 1).

The time to complete NTI (NTI time) was significantly longer in the fiberoptic group than in the Disposcope group (38.4 sec vs 24.1 sec; mean difference, 14.2 sec; 95% CI, 10.4 to 18.1) (Table 2).

Mild epistaxis (nasal bleeding) was observed in 8 patients in the fiberoptic group and 7 patients in the Disposcope group (26.7% vs 23.3%, respectively; relative risk, 1.2; 95% CI, 0.4 to 3.9). No moderate or severe epistaxis occurred in either group (Table 2).

Furthermore, no obvious nasal pain was reported at any time point after extubation in the Disposcope endoscope group, and there was no significant difference between the two groups (data not shown).

Discussion

Fiberoptic bronchoscopy-guided NTI is a well-established and safe technique with a high success rate and low morbidity. In this study, both fiberoptic bronchoscopy and Disposcope endoscope-guided NTI were successfully completed without any severe adverse reactions. However, the Disposcope endoscope, which is a video laryngoscope, required less transaction time than were required when using fiberoptic bronchoscopy. This is the first study in which the Disposcope endoscope was used for NTI.

Fiberoptic bronchoscopy-guided NTI performed via the nasal route is a favoured and popular procedure. Shih et al [8]. reported that performing the one-hand manoeuvre was not only time-saving but also reduce the need for assistance in patients requiring fiberoptic bronchoscopy-guided NTI for reasons other than a difficult airway. However, they suggested that the one-hand manoeuvre was not suitable for novices, and a trained assistant should always be available in case of finger and hand fatigue or other unpredictable conditions [8]. Head tilt with chin lift techniques provide adequate airway support for patients with and without limited mouth opening [10]. In this study, the NTI time were significantly lower in the Disposcope group than in the fiberoptic group. The main reasons were as follows. First, the wire tube body of Disposcope endoscopy was rigidly, then the full use of the left hand (or right hand depending on personal preference) was available to lift the mandible to perform a chin lift. Second, in the fiberoptic group, we needed to use the left hand to help during wire tube body insertion because of its softness, and in most cases, we spent a longer period of time finding the glottis.

Previous studies have discussed many ways to reduce the risk of epistaxis during NTI in the clinic. First, data have shown that less epistaxis occurred during NTI and intubation was faster in the right than in the left nostril, an effect related to the anatomy of structures located on the posterior nasopharyngeal wall; thus, the right nostril should be chosen if patency appears to be equal on both sides of the nose [1, 11, 12]. It was also reported that measurement of the nasal flow rate is a useful clinical method for choosing which nostril to use for NTI [13]. Second, using a Parker Flex-Tip tube not only helps to minimize the incidence of nasal mucosal trauma during nasotracheal intubation but may also increase patient safety and comfort [14]. Another study reported that using a stylet-Parker tube enhanced the ease of insertion through the nasopharynx and reduced the risk of epistaxis during NTI [15]. In contrast, Earle et al [9]. found that compared to a standard tube, a Parker tube did not significantly reduce epistaxis during NTI. Therefore, stylet-Parker tubes were not used in our study. Furthermore, performing NTI under suction catheter guidance represents a simple and effective method for smoothly introducing a nasal endotracheal tube and reducing nasal bleeding during NTI [16]. In other studies, the placement of a bougie through a nasopharyngeal airway may also act to protect the nasal mucosa and guide the tracheal tube and was associated with less epistaxis as well as better navigability and a lower redirection rate [3, 17]. In the present study, no moderate or severe epistaxis occurred in either group, perhaps for the following reasons: each nostril was preestimated for size and patency by fiberoptic bronchoscopy, and five drops of 1 % ephedrine solution were instilled into the larger nasal cavities to prevent bleeding. Then, NTI was performed under the guidance of suction catheters. Moreover, the use of wire-reinforced tracheal tubes and aseptic suction catheters may also decrease the incidence of epistaxis.

In the Disposcope group, a rigid wire transfer was inserted into the tube during NTI. However, in this study, no obvious nasal pain was reported at each time point after extubation in the Disposcope group, and there was no significant difference between the groups. We hypothesized that the wire-reinforced tracheal tubes may have protected the nasal mucosa and the whole nasal passage during the surgery. In previous studies, the fiberoptic group was associated with a lower rate of sore throat after NTI than was found when using the Macintosh laryngoscope [4]; we didn’t observe the rate of sore throat in our study for some surgeries about vocal cords.

Admittedly, there are several limitations to our study that should be considered. First, fiberoptic bronchoscopy-guided NTI is widely known for its effectiveness in patients who have difficult airways. Unfortunately, patients with preoperative Mallampati scores of III or greater were excluded from our study because we aimed to evaluate two methods of guided NTI in selective oral and maxillofacial surgeries. Therefore, further study will be needed to confirm this effect, and we will be working on this issue. Furthermore, the NTI time is also probably not clinically important when the difference is only a dozen seconds, which may not indicate clear superiority but may suggest an optimal choice. However, we considered it necessary in case of an emergency.

Conclusion

NTI can be successfully completed using fiberoptic bronchoscopy or a Disposcope endoscope as a guide without any severe adverse reactions. However, the Disposcope endoscope, which is a video laryngoscope, required less transaction time than were required when using fiberoptic bronchoscopy.

Abbreviations

NTI: Nasotracheal intubation; ASA: American Society of Anaesthesiologists; BMI: body mass index; VAS: visual analogue scale

Declarations

Acknowledgments

The authors would like to thank all the staff of Department of Anesthesiology, The First People’s Hospital of Hefei, Anhui Medical University for being helpful in conducting and finishing this research.

Funding

No funding was obtained for this study.

Availability of data and materials

The datasets analysed during the current study are available from the corresponding author on reasonable request.

Author’s contributions

Junma Yu, Rui Hu, Lining Wu and Peng Sun were responsible for the study design and planning. Junma Yu and Rui Hu were responsible for the study. Junma Yu and Zhi Zhang performed the data analysis. Junma Yu and Zhi Zhang wrote the paper. All authors participated in revising the paper.

Ethics approval and consent to participate

This study protocol was approved by the Institutional Research Ethics Committee of The First People’s Hospital of Hefei (No. 2016-6) and was registered in the Chinese Clinical Trial Registry (www.chictr.org.cn, ChiCTR-IPR-17011462). Written informed consent was obtained from all patients.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no compting interests.

References

1. Sanuki T, Hirokane M, Kotani J. Epistaxis during nasotracheal intubation: a comparison of nostril sides. J Oral Maxillofac Surg. 2010; 68(3): 618-21.
2. Kihara S, Komatsuzaki T, Brimacombe J R,  Yaguchi Y, Taguchi N, Watanabe S. A silicone-based wire-reinforced tracheal tube with a hemispherical bevel reduces nasal morbidity for nasotracheal intubation. Anesth Analg. 2003; 97(5): 1488-91.
3. Kwon MA, Song J, Kim S, Ji SM, Bae J. Inspection of the nasopharynx prior to fiberoptic-guided nasotracheal intubation reduces the risk epistaxis. J Clin Anesth. 2016; 32: 7-11.
4. Tachibana N, Niiyama Y, Yamakage M. Less postoperative sore throat after nasotracheal intubation using a fiberoptic bronchoscope than using a Macintosh laryngoscope: A double-blind, randomized, controlled study. J Clin Anesth. 2017; 39: 113-7.
5. Sato Boku A , Sobue K , Kako E , Tachi N, Okumura Y, Kanazawa M, Hashimoto M, Harada J. The usefulness of the McGrath MAC laryngoscope in comparison with Airwayscope and Macintosh laryngoscope during routine nasotracheal intubation: a randomaized controlled trial. BMC Anesthesiol. 2017; 17(1):160.
6. Park SO, Shin DH, Lee KR, Hoog DY, Kim EJ, Baek KJ. Efficacy of the Disposcope endoscope, a new video laryngoscope, for endotracheal intubation in patients with cervical spine immobilisation by semirigid neck collar: comparison with the Macintosh laryngoscope using a simulation study on a manikin. Emerg Med J. 2013; 30(4): 270-4.
7. Chen PT, Ting CK, Lee MY, Cheng HW, Chan KH, Chang WK. A randomised trial comparing real-time double-lumen endobronchial tube placement with the Disposcope® with conventional blind placement. Anaesthesia. 2017; 72(9): 1097-106.
8. Shih CK, Wu CC, Ji TT. One-hand maneuver to facilitate flexible fiber-optic bronchoscope-guided nasotracheal intubation insedated patients. Acta Anaesthesiol Taiwan. 2015; 53(4): 150-1.
9. Earle R, Shanahan E, Vaghadia H, Sawka A, Tang R. Epistaxis during nasotracheal intubation: a randomized trial of the Parker Flex-Tip™ nasal endotracheal tube with a posterior facing bevel versus a standard nasal RAE endotracheal tube. Can J Anaesth. 2017; 64(4): 370-5.
10. Cheng KI, Yun MK, Chang MC, Lee KW, Huang SC, Tang CS, Chen CH. Fiberoptic bronchoscopic view change of laryngopharyngeal tissues by different airway supporting techniques: comparison of patients with and without open mouth limitation. J Clin Anesth. 2008; 20(8): 573-9.
11. Boku A, Hanamoto H, Hirose Y, Kudo C, Morimoto Y, Sugimura M, Niwa H. Which nostril should be used for nasotracheal intubation: the right or left? A randomized clinical trial. J Clin Anesth. 2014; 26(6): 390-4.
12. Takasugi Y, Futagawa K, Konishi T, Morimoto D, Okuda T. Possible association between successful intubation via the right nostril and anatomical variations of the nasopharynx during nasotracheal intubation: a multiplanar imaging study. J Anesth. 2016; 30(6): 987-93.
13. Lim HS, Kim D, Lee J, Son JS, Lee JR, Ko S. Reliability of assessment of nasal flow rate for nostril selection during nasotracheal intubation. J Clin Anesth. 2012; 24(4): 270-4.
14. Sanuki T, Hirokane M, Matsuda Y, Sugioka S, Kotani J. The Parker Flex-Tip™ tube for nasotracheal intubation: the influence on nasal mucosal trauma. Anaesthesia. 2010; 65(1): 8–11.
15. Sugiyama K, Manabe Y, Kohjitani A. A styletted tracheal tube with a posterior-facing bevel reduces epistaxis during nasal intubation: a randomized trial. Can J Anaesth. 2014; 61(5): 417-22.
16. Morimoto Y, Sugimura M, Hirose Y, Taki K, Niwa H. Nasotracheal intubation under curve-tipped suction catheter guidance reduces epistaxis. Can J Anaesth. 2006; 53(3): 295-8.
17. Abrons R O, Vansickle R A, Ouanes J P. Seldinger technique for nasal intubation: a case series. J Clin Anesth. 2016; 34: 609-11.

Tables

Table 1 Patients’ characteristics and duration of anesthesia

Values are expressed as number or mean (SD)

Table 2 NTI time and the epistaxis incidence in the groups

Values are expressed as number, proportion (%) or mean (standard deviation). Relative risk are calculated for categorical data. CI = confidence interval