In this study, using E or T as a vasoconstrictor, we observed no difference in the frequency and degree of bleeding between the groups. Factors influencing the frequency of bleeding may include the patient’s sex and the years of experience of the intubator. However, in this study, both groups had similar characteristics, which is ideal for proper investigation if the potential bleeding occurrence was only associated with the vasoconstrictor.
Nasal bleeding due to NTI is mostly caused by damaging of the venous plexus in the middle nasal mucosa, the curvature of the nasal septum, and adenoid enlargement [16]. In addition, nasal bleeding during NTI can obstruct the airway patent and cause serious complications such as airway obstruction. Considering that persistent bleeding can also affect the operative field, every effort should be made to prevent bleeding whenever possible. Vasoconstrictors are used to achieve local hemostasis by constricting the intramucosal capillaries and reducing blood flow, thereby expanding the nasal volume and facilitating the passage of the intubation tube through the nasal cavity [16].
Epinephrine is the most common vasoconstrictor for local hemostatic purposes, with recommended concentrations of 0.1–0.02% [17]. Previous studies [11, 18] using E to prevent nasal bleeding reported hemorrhage rates of 37% [11] and 60% [18], which are considerably higher than the 12.5% of nasal bleeding observed in the present study. This discrepant finding may be attributed to the concentration of E, nasal stenosis, and left-right differences in the nasal cavity used. Note that both previous studies [11, 18] used an E concentration of 0.01%, whereas in our study we used a concentration of 0.02%. Although some blood pressure fluctuation was observed before and after use of E, it was not clinically problematic, and the 0.02% concentration could be used without problems. Furthermore, E has an onset of action of 5 min and lasts for 1 h [18]. For practical reasons, we set a time of 2 min (instead of 5 min) and we found that a 2-min period was sufficient to achieve hemostasis.
In this study, as patients were undergoing dental surgery, a computed tomography of the facial area was taken in all cases prior to the study. Therefore, it was possible to include nasal stenosis as an exclusion criterion for the current study. Hence, despite the 4-year average intubation experience, the passage of the intubation tube was smooth and performed at once in all patients. Moreover, all patients were intubated using the right nasal cavity, as we have previously reported less epistaxis in the right nasal cavity compared with the left nasal cavity [7]. Unlike the current study, Sonan et al [18] used the left nasal cavity for intubation, but it is unclear which nasal cavity was used in the study by Jaegyok et al.[11] We believe that the above three factors contributed to the lower percentage of bleeding observed in our study than in the previous studies [11, 18].
In contrast, we also used T as a vasoconstrictor in this study. T stimulates alpha-2 receptors and constricts local blood vessels in the nasal cavity, eliminating hyperemia and swelling of the nasal mucosa [19]. There are reports that nasal T infusion improves rhinitis [20] and sleep apnea [21]. To the best of our knowledge, there are no reports regarding use of T for preventing nasal bleeding during NTI. Our findings indicate that T is as effective as E regarding prevention of nasal bleeding during NTI. The blood pressure fluctuation observed in the present study during the use of both drugs is due to the sympathetic stimulating effects of both drugs. Although the blood pressure fluctuations in both groups were clinically safe, E increased blood pressure more than T, suggesting that E stimulates alpha receptors more strongly than T within the concentrations used in this study. Although patients with hypertension were excluded from the study, the use of both drugs increased blood pressure of normotensive patients, suggesting the need for extremely careful judgment while using these drugs in hypertensive patients.
In the present study, we also found that the use of both drugs did not induce arrhythmias. It has also been reported that the use of E for the prevention of nasal bleeding usually has a minimal effect on circulation in many patients [22, 23]. However, sudden tachycardia was reported when E was used to prevent nasal bleeding [14]. In that study, it was assumed that severe tachycardia was triggered by submucosal migration of an epinephrine-soaked swab. Hence, even at normal concentrations of E, when the mucous membrane is injured by swabs or other means, it is important to consider that a rapid increase of concentration of E in the blood may induce arrhythmia. In the present study, total intravenous anesthesia was used in all patients. However, previous studies reported a decrease in the arrhythmia range of E in combination with volatile anesthetics with halogenated anesthetics ranging from halothane to sevoflurane [24, 25]. Therefore, attention should be given to variations in circulation dynamics while using E.
The major limitation of this study is the exclusion of patients with nasal stenosis; different results could be expected if patients with nasal stenosis were included. However, mixing of patients with and without nasal stenosis in the same trial must be avoided. This issue should be investigated in future studies.
In conclusion, nasal treatment with E or T shows no difference in nasal bleeding during NTI. Although no arrhythmia associated with E was observed in this study, it has been reported in the literature. Therefore, as the frequency and degree of nasal bleeding were comparable, nasal treatment with T could reduce the risk of NTI.