Introduction
Patients undergoing maxillofacial surgery frequently undergo nasotracheal intubation. Nasotracheal intubation is associated with complications such as epistaxis, nasal septal injury, turbinate fracture, blood aspiration, and airway obstruction [1]. Among these, epistaxis is the most common complication. Damage to the Kiesselbach’s plexus in the anterior portion of the nasal septum, rather than injury of the turbinates, induces epistaxis in the majority of cases [2–4]. Epistaxis can occasionally induce life-threatening complications [5,6]. Thus, various strategies such as the administration of nasal decongestants and lubricants, optimal nostril selection, and optimizing the selection of nasotracheal tube materials have been devised to reduce the incidence of epistaxis [1]. However, despite the implementation of these prevention strategies and efforts [7–12], epistaxis remains a frequent and troublesome complication. The association between the side of the nostril being intubated and the direction of the bevel or tip of the nasotracheal tube may affect the incidence of epistaxis and duration of intubation [13–15]. Compared to the right nostril, nasotracheal intubation via the left nostril is associated with a higher incidence of epistaxis (19% vs. 42%; 11% vs. 44%) [13,14]. However, patients undergoing right-sided maxillofacial surgery, such as reconstruction surgery, open reduction, and internal fixation, or excision in the right maxillofacial region, often require nasotracheal intubation via the left nostril.
Previous studies have investigated the efficacy of various nasotracheal tube rotation techniques for safe and effective nasotracheal intubation. A 90° anticlockwise pre-rotation of the standard nasotracheal tube reduced impingement and increased the first attempt success rate in previous studies [16,17]. Furthermore, compared with conventional methods, this rotation reduced the incidence of epistaxis during left nasotracheal intubation [18].
A 180˚ rotation of the tube, rather than a 90° anticlockwise rotation, may prevent the injury of the nasal septum with the Kiesselbach’s plexus during left nasotracheal intubation. We hypothesized that a 180˚ reverse bevel and tip direction of the nasotracheal tube would reduce the incidence of epistaxis in patients undergoing videolaryngoscopy-guided nasotracheal tube insertion via the left nostril. Thus, this study aimed to compare the incidence of epistaxis between the conventional method and the 180˚ reverse tube method in patients undergoing nasotracheal tube insertion via the left nostril.
Materials and Methods
This study was approved by the Institutional Review Board of Asan Medical Center, Seoul, Republic of Korea (approval number: 2021-1453). Written informed consent was obtained from all participants. The trial was registered at the Clinical Research Information Service (registration number: KCT0006672) before participant enrollment. This trial was conducted in accordance with the original study protocol. The procedures were conducted in accordance with the Helsinki Declaration-2013.
Participants
Patients who met the following inclusion criteria were enrolled in this study between November 2021 and September 2023: age 20–79 years, American Society of Anesthesiologists physical status I–III, and requiring nasotracheal intubation via the left nostril owing to undergoing right-sided maxillofacial surgery. Patients with a history of recent upper respiratory infection; external nasal deformities, such as loss of skin elastosis and structural support in the osseocartilaginous framework; bleeding tendency; history of anticoagulant use; history of recurrent epistaxis; history of nasal surgery; predicted difficult airway for nasotracheal intubation, such as obstruction of the nasal cavity, severe septal deviation, restricted mouth opening, limited neck extension, and pharyngeal pathology; risk of regurgitation; and airway obstruction at or below the level of the larynx or thyromental distance of less than 6 cm were excluded from this study. Airway examinations and a review of facial computed tomography images were conducted before patient enrollment to exclude patients who met the exclusion criteria.
Randomization, concealment, and blinding
The participants were randomized before commencing recruitment. The first investigator generated a random number table using web-based randomization software (Random Allocation Software version 1.0®, Mahmood Saghaei, Isfahan University of Medical Sciences). Eligible participants were allocated to the control or reverse group. The second investigator inserted the nasotracheal tube after confirming the randomization code and assessed the outcomes of nasotracheal intubation such as the incidence and severity of epistaxis. The third investigator assessed the intraoperative outcomes, and the fourth investigator assessed the postoperative outcomes.
Study protocol
The eligible patients were educated on postoperative nasal pain, nasotracheal intubation-related complications, and the patient satisfaction scale before the surgery. The patients were monitored according to the institutional standards on entering the operating room. General anesthesia was induced using thiopental after pre-oxygenation with 100% oxygen. Rocuronium was administered, followed by mask ventilation using sevoflurane in 100% oxygen for 3 min. Two puffs of xylometazoline 0.1% nasal spray (Otrivin 0.1%®, Novartis) were applied to the nasal mucosa in the left nostril after the patient lost consciousness [19]. Nasal Ring, Adair and Elwyn (RAE) (Mallinckrodt Preformed Nasal RAE tube®, Covidien) tubes with an internal diameter of 7.0 mm and 6.0 mm were used for men and women, respectively. The nasotracheal tube was placed in a bottle containing sterile normal saline at 45°C in a warming cabinet for 30 min to facilitate thermosoftening. The nasotracheal tube in the sterile normal saline bottle was removed from the cabinet during mask ventilation for intubation. The nasotracheal tube was withdrawn from the normal saline bottle and lubricated with water-soluble jelly immediately before intubation.
Nasotracheal intubation was performed after the patient had lost consciousness and the train-of-four count was 0. All intubation procedures were performed by one anesthesiologist skilled in videolaryngoscopy-guided nasotracheal intubation in this study. The nasal RAE tube was inserted via the left nostril with the following bevel directions: the conventional bevel direction (control group) or the reverse bevel direction (reverse group). The nasotracheal tube was gently introduced into the left nostril in the conventional bevel direction in the control group. The bevel of the nasotracheal tube faced the opposite side of the nasal septum, with the leading edge (i.e., the tip) of the bevel of the nasotracheal tube pointed toward the nasal septum (Fig. 1A). The nasotracheal tube was gently introduced into the left nostril in the 180˚ reverse bevel and tip direction in the reverse group. The bevel of the nasotracheal tube faced the nasal septum, with the leading edge of the bevel of the nasotracheal tube pointing away from the nasal septum (Fig. 1B). The nasotracheal tube was advanced into the nasal cavity after the insertion of the tip via the left nostril and passed into the oropharynx. The nasotracheal tube was withdrawn slightly if resistance was encountered, and reinsertion was attempted twice using the same method initially assigned to the group. Unsuccessful left nasotracheal intubation after two attempts was deemed a failure; right nasotracheal intubation or orotracheal intubation was considered in such cases.
The videolaryngoscope (KoMAC®, Korea Medical Devices Co., Ltd.) was inserted once the tip of the nasotracheal tube had entered the pharynx in both groups. The tube was advanced from the oropharynx to the glottis inlet after determining the severity of epistaxis via videolaryngoscopy. Magill forceps were used when needed. The placement of the tube in the trachea was confirmed based on the breathing sounds on auscultation and square-wave on capnography.
Assessments
Nasotracheal intubation variables such as the severity of epistaxis, overall nasotracheal intubation success, first attempt nasal passage success, and total passage time were assessed [11,13]. The severity of epistaxis visualized via videolaryngoscopy was evaluated using the following four-point scale: no epistaxis, mild epistaxis (blood present only on the nasotracheal tube), moderate epistaxis (pooling of blood in the pharynx), and severe epistaxis (pooling of blood in the pharynx sufficient to impede intubation) [7,12]. The incidence of epistaxis was defined as the presence of mild to severe epistaxis. The overall success of nasotracheal intubation was defined as successful nasotracheal intubation under videolaryngoscopy-guidance in two attempts [11]. First attempt nasal passage success was defined as the passage of the tube from the left nostril to the pharynx in one attempt.
Intraoperative and postoperative variables such as duration of anesthesia, duration of surgery, postoperative nasal pain, postoperative persistent epistaxis, nasotracheal intubation-related complications, and duration of hospitalization were assessed. Postoperative nasal pain was assessed at 1 h postoperatively using the numeric rating scale [7]. Postoperative persistent epistaxis was defined as the confirmed presence of epistaxis after the completion of surgery [7]. Postoperative persistent epistaxis and the incidence of nasotracheal intubation-related postoperative complications such as nasal septal injury, turbinate avulsion, turbinate fracture, or blood aspiration were assessed on postoperative day 1. The duration of hospitalization was defined as the period from the day of the surgery to the day of discharge. Nasotracheal intubation-related patient satisfaction was assessed using a seven-point Likert scale at 1 h postoperatively, with each score indicating the following: 1 = strongly dissatisfied, 2 = moderately dissatisfied, 3 = slightly dissatisfied, 4 = neutral, 5 = slightly satisfied, 6 = moderately satisfied, and 7 = extremely satisfied [20].
Statistical analysis
This study was a superiority trial that aimed to evaluate the effect of 180˚ reverse bevel and tip direction during left nasotracheal intubation on the incidence of epistaxis. The incidence of left nasotracheal intubation-related epistaxis was 44.0% [8]. Based on our experience, the use of the 180˚ reverse bevel and tip direction technique for left nasotracheal intubation reduced the incidence of epistaxis by approximately 70%. Therefore, it was assumed that the reverse bevel and tip direction for left nasotracheal intubation would decrease the incidence of epistaxis by 70.0% (44.0% vs. 13.2%). Sample size calculation was based on this assumption; our sample size calculation showed that 33 patients in each group would be necessary to attain statistical significance, with two-sided α = 0.05 and β = 0.2. Thirty-seven patients were included in each group considering a dropout rate of 10%.
Enrollment was ceased when the target sample size was obtained. The analyses were performed on an intention-to-treat basis. All enrolled patients who were randomly allocated to receive the intervention were included in the analysis. Data are expressed as mean ± standard deviation (SD), median (Q1, Q3), number (proportion), relative risk, 95% CI, absolute risk reduction, or number needed to treat, as appropriate. This study focused on the incidence of epistaxis as the primary outcome measure that was compared using the chi-square test. Continuous variables were compared using the independent t-test or Mann-Whitney U test, as appropriate. Categorical variables were compared using the chi-square test or Fisher’s exact test, as appropriate. All P values were two-sided, with P values < 0.05 indicating statistical significance. All statistical analyses were performed using MedCalc (MedCalc version 11.3.3.0®, MedCalc Software Ltd.) and SPSS (SPSS version 21.0.0®, IBM Corporation).
Results
Among the 104 patients assessed for eligibility during the enrollment process, 30 patients, comprising 25 patients who met the exclusion criteria and five patients who declined participation, were excluded. The patients meeting the exclusion criteria included those with external anatomical changes (n = 5), those with a history of anticoagulant use (n = 4), those with a history of recurrent epistaxis (n = 2), those with a history of nasal surgery (n = 9), and those with a predicted difficult airway for nasotracheal intubation (n = 5). The remaining 74 randomized patients (including two patients in the control group and one patient in the reverse group who did not receive the allocated intervention) were included in the final analysis (Fig. 2).
The characteristics of the patients in both groups were similar (Table 1). The incidence of epistaxis in the reverse group was significantly lower than that in the control group (9 [24.3%] vs. 20 [54.1%], P = 0.009; relative risk: 0.45, 95% CI [0.24, 0.85], absolute risk reduction: 29.8%, number needed to treat: 3) (Fig. 3). The severity of epistaxis in the reverse group was significantly lower than that in the control group (P = 0.002, Table 2). Failure of left nasotracheal intubation occurred in one and two patients in the reverse and the control groups, respectively; these patients were intubated via the right nostril. The overall nasotracheal intubation success rate did not differ between the reverse and control groups; however, the first attempt nasal passage success in the reverse group was significantly higher than that in the control group (78.4% vs. 54.1%, P = 0.027; relative risk: 1.44, 95% CI [1.17, 1.78], absolute risk reduction: 24.3%, number needed to treat: 4). The total passage time did not differ between the two groups.
The duration of anesthesia and surgery did not differ between the reverse and control groups (170 [121, 313] min vs. 151 [93, 239] min, P = 0.275; 120 [72, 252] min vs. 108 [52, 173] min, P = 0.320, respectively). Postoperative nasal pain at 1 h after surgery was significantly lower in the reverse group than that in the control group (2 ± 1 vs. 4 ± 2, P < 0.001). Postoperative persistent epistaxis, nasal septal injury, turbinate fracture, or blood aspiration were not observed in either group. No significant differences were observed between the reverse and control groups in terms of the duration of hospitalization (2 [1, 5] days vs. 3 [1, 5] days, P = 0.604). Nasotracheal intubation-related patient satisfaction score at 1 h postoperatively in the reverse group was significantly higher than that in the control group (6 [5, 6] vs. 4 [3, 6], P < 0.001).
Discussion
This study revealed that left nasotracheal intubation with a 180˚ reverse bevel and tip direction resulted in a significant decrease in the incidence and severity of epistaxis. The first attempt nasal passage success rate was higher in the reverse group. Moreover, the reverse bevel and tip direction decreased postoperative nasal pain. Nasotracheal intubation-related postoperative complications were not encountered in either group.
Epistaxis is a frequent complication of nasotracheal intubation. Previous studies have reported that the incidence of epistaxis during nasotracheal intubation ranges from 18% to 77% [21]. Several strategies have been proposed to prevent the incidence of epistaxis, including the use of nasal decongestants and lubricants, the selection of optimal nostril, and optimizing the material of the nasotracheal tube [1,18]. Recent studies comparing different nasotracheal tube materials have demonstrated that the choice of tube material can reduce the incidence of epistaxis. For instance, compared with conventional tubes or spiral tube, the use of velvet-soft polyvinyl chloride tube significantly reduced the incidence of epistaxis [22,23].
The selection of the right or left nostril plays a crucial role in the prevention of epistaxis. Selection of the right nostril is advocated to reduce the incidence of epistaxis induced by nasotracheal intubation when the patency of the nostrils is unclear. The incidence of epistaxis among patients who underwent nasal intubation via the left nostril was higher than that among those who underwent intubation via the right nostril in previous studies [13–15]. This difference can be attributed to the relationship between the position of the bevel of the endotracheal tube and the nasal septum. The bevel of the tube is located on the left side of the tube, while the leading edge of the bevel is positioned on the right side of the tube. When left nasotracheal intubation is performed, therefore, the leading edge of the bevel points toward the nasal septum that is the main site of epistaxis. Based on these considerations, numerous studies suggest opting for intubation via the right nostril to minimize the incidence of epistaxis [13,14,24]. However, situations frequently arise where left nasotracheal intubation becomes imperative owing to the specific surgical site, leading to a heightened risk of epistaxis. Therefore, it is essential to identify optimal approaches for reducing the incidence of epistaxis during left nasotracheal intubation.
The incidence of epistaxis during left nasotracheal intubation was significantly lower in the reverse group than that in the control group in the current study. Additionally, the severity of epistaxis was lower in the reverse group. Whether the tube bevel should face the turbinate or the septum to reduce the incidence of epistaxis during nasotracheal intubation remains unclear. Previous studies have recommended making the bevel face the turbinate, with the tip of the tube positioned against the septum, to reduce the risk of trapping the tip on a turbinate that can result in tearing or dislocation during nasotracheal intubation [25]. However, recent studies on the association between the nostril side and the incidence of epistaxis during nasotracheal intubation have demonstrated that the tube bevel should face the nasal septum, with the leading edge of the bevel pointing away from the nasal septum, to prevent the incidence of epistaxis [13,14,24]. These findings are consistent with those of the current study. Furthermore, a 90° anticlockwise rotation of the nasotracheal tube decreased the incidence of epistaxis during nasotracheal intubation [18]. This can be attributed to the relation of the nasal septum with the Kiesselbach’s plexus. The Kiesselbach’s plexus that is located in the anterior part of nasal septum is the most common site of epistaxis [2]. Moreover, it is often injured during nasotracheal intubation with the nasotracheal tube bevel and tip [26]. The tracheal tube should be inserted into the nasal cavity with the leading edge of the bevel on the lateral side of the naris to avoid the incidence of epistaxis [26]. The 180˚ reverse bevel and tip direction of the nasotracheal tube in this study seemed to cause lesser injury to the septum as the reverse tube bevel faced the septum and the leading edge of the bevel was positioned on the opposite side of the septum, resulting in a lower incidence of epistaxis in left nasotracheal intubation.
Nasotracheal intubation-related patient satisfaction in the reverse group was significantly higher than that in the control group in the current study. This may be attributed to the decrease in postoperative nasal pain associated with lesser nasal injury in the reverse group. All participants of this study underwent right-sided maxillofacial surgery, and it may be difficult to completely distinguish surgical site pain and nasal pain. Nevertheless, this can be overcome with strict education prior to study enrollment [7].
The reverse bevel and tip direction of the nasotracheal tube in the left nostril in the current study is similar to the conventional bevel direction of nasotracheal tube at the right nostril; thus, both right nostril nasotracheal intubation with the conventional bevel direction and left nasotracheal intubation with the reverse bevel and tip direction can reduce the incidence of epistaxis. To the best of our knowledge, this is the first study to evaluate the effect of reverse bevel and tip direction of the nasotracheal tube on the incidence of epistaxis during left nasotracheal intubation.
Our study has several limitations. Firstly, epistaxis during nasotracheal intubation was defined using a videolaryngoscopy-based four-point scale. Numerous definitions have been proposed for epistaxis, and the definition used in this study seems to be subjective. However, akin to our study, numerous previous studies have used the four-point epistaxis scale [8–13,17]. Furthermore, videolaryngoscopy, not direct laryngoscopy, was used to ensure a more accurate assessment of epistaxis in the current study. Therefore, the definition of epistaxis used in the current study can be considered reasonable. Secondly, the effect of nasal cycle was not considered [27]. The physiologic nasal cycle can affect nasal obstruction or epistaxis. However, mucosal decongestant were applied to reduce mucosal congestion induced by the nasal cycle [28]. Furthermore, the effect of the nasal cycle was likely minimal as this was a randomized controlled trial. The nature of the study ensured that variables such as the nasal cycle were similarly distributed between the groups. Lastly, secondary outcomes such as epistaxis severity, overall nasotracheal intubation success, first attempt nasal passage success, total passage time, postoperative nasal pain, nasotracheal intubation-related complications, and nasotracheal intubation-related patient satisfaction were evaluated. Therefore, this study is expected to provide valuable information not only on the incidence of epistaxis but also on aspects related to nasotracheal intubation. Nevertheless, further research on a broader range of outcomes is warranted.
In conclusion, reversing the bevel and tip direction of the nasotracheal tube led to a decrease in the incidence and severity of epistaxis, along with a reduction in postoperative nasal pain, in left nasotracheal intubation. Moreover, this modification increased the first attempt nasal passage success and patient satisfaction. These findings imply that implementing the reverse bevel and tip direction of the nasotracheal tube may be an effective strategy for decreasing the incidence of epistaxis in patients undergoing left nasotracheal intubation.
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