INTRODUCTION
Nasotracheal intubation is commonly used to maintain the airway under general anesthesia during dental surgery. This technique minimizes interference of the surgical view caused by the tracheal tube (TT) and facilitates surgical access. However, advancing the TT through the nasal passage can traumatize the highly vascular nasal mucosa, often causing epistaxis or even life-threatening complications, such as airway obstruction [1].
Children are more vulnerable to epistaxis due to smaller nasal apertures, narrow nasal cavities, hypertrophied turbinates, and enlarged adenoids [2]. Therefore, caution should be exercised to avoid epistaxis when performing nasotracheal intubation in children. Common methods for reducing epistaxis include warming the TT, applying topical vasoconstrictors, and lubricating the TT [1,3,4]. Despite these modifications, nasotracheal intubation remains associated with nasal trauma and epistaxis.
In a study aimed at identifying risk factors associated with epistaxis during nasotracheal intubation, Sim et al. [3] found that difficult transit of the TT through the nasal passage was the only independent risk factor for epistaxis. Conventional nasotracheal intubation was performed blindly during the TT transit through the nasal passage. In the present study, we tested a guide-based method using an esophageal temperature probe (ETP) to facilitate nasal passage of the TT and reduce epistaxis during nasotracheal intubation in children.
METHODS
This study was approved by the Institutional Review Board (IRB) of the Jeju National University Hospital (IRB No. 2021-06-011) and registered with the Korea Clinical Research Information Service (No. KCT0008972). Written informed consent from the parents and written assent from the children were obtained preoperatively.
Forty-eight children were assessed for eligibility. Ultimately, this study included 42 patients 3-12 years of age, with an American Society of Anesthesiologists physical status of 1 or 2, and requiring nasotracheal intubation for dental surgery (Fig. 1). Patients in whom difficult airway management was anticipated, and those with a history of nasopharyngeal surgery or recurrent epistaxis, were excluded.
No preanesthetic medication was administered. On entering the operating room, patients underwent electrocardiography, non-invasive blood pressure measurements, pulse oximetry, and capnography. After induction of general anesthesia with thiopental (5 mg/kg) and neuromuscular blockade with rocuronium (0.6 mg/kg), the lungs were ventilated with 6% sevoflurane in 100% oxygen.
The most patent nostril, as determined by the patient, was selected for intubation. If both nostrils appeared similar, the right nostril was used to initiate intubation. During mask ventilation, the nasal cavity was packed with swabs soaked in dilute epinephrine. The size of the TT (ShileyTM Lo-Contour Oral/Nasal Tracheal Tube Cuffed Reinforced; Covidi-en, Dublin, Ireland) was selected according to the equation: (age [years]/4)+3 [5]. The TT was softened by dipping it into warm water and lubricated with sterile water-soluble lubricant.
Eligible patients were randomly allocated to the guidance group (group G) or conventional group (group C). In group G, the ETP (ST ProbeTM 9 Fr; S&S Med, Gunpo, Korea) was first inserted into the TT so that the ETP protruded from the distal end of the TT (Fig. 2). The tip of the ETP was inserted through the nostril along the floor of the nose until it reached the oropharynx. The TT was advanced along the ETP, while holding the proximal ETP to prevent further forward movement. Once the TT reached the oropharynx, the ETP was removed and intubation was completed using direct laryngoscopy. In group C, the TT was conventionally inserted without the ETP using a blind nasal passage technique.
Attempts at nasal passage were also recorded. If the attempt took more than 90 seconds or pulse oximetry dropped to <95%, the patient received mask ventilation before the second attempt. If successful nasal passage was not achieved within two attempts, it was considered a failure, and orotracheal intubation was performed. The time to nasal passage was measured from the insertion of the TT into the nostril until it passed into the oropharynx, and was recorded as the sum of the times of the two attempts.
The anesthesiologist who performed the intubation evaluated the navigability during the transit through the nasal passage and categorized as smooth (minimal feeling of obstruction) or impinged (any feeling of obstruction) [6]. Another anesthesiologist, who did not attend the nasotracheal intubation, assessed the extent of epistaxis as mild (no blood or blood on the TT only) or obvious (some blood pooling in the pharynx) [7].
Based on the results of a previous study, 7 which reported a 34% difference between the groups regarding impinged navigability in children, the calculated sample size was 21 patients per group, with an alpha error of 0.05 and a power of 0.8. To compare variables, the chi-squared or Fisher’s exact test was used for categorical data, and the Mann-Whitney test was used for numerical data. All data were analyzed using SPSS version 20.0 (IBM, Armonk, NY, USA) and differences with P<0.05 were considered to be statistically significant.
RESULTS
There were no significant differences in patient characteristics between the groups. The success rate of nasotracheal intubation was 100% in both groups. The time to nasal passage was similar between the groups.
The frequency of impinged navigability during the transit through the nasal passage was significantly lower in group G than that in group C (38.1% vs. 71.4%; P=0.030). The frequency of obvious epistaxis was also significantly lower in group G than that in group C (14.3% vs. 47.6%; P=0.019) (Table 1).
DISCUSSION
This randomized study evaluated the use of the ETP to guide nasotracheal intubation in children undergoing dental surgery. The ETP-guided group experienced approximately 30% less nasal bleeding and had significantly easier navigation than the conventional group. These findings suggest that using an ETP as a guide may minimize nasal trauma and enhance the ease and safety of nasotracheal intubation in children.
Epistaxis is the most common complication during nasotracheal intubation, with an incidence ranging from 18% to 77% [8-10]. This complication is mainly caused by mucosal trauma from the rigid tip or sharp-edged Murphy eye of the TT as it passes through the narrow passage [11,12]. The risk for damage increases with larger tube sizes or when resistance is encountered during insertion, leading to trauma of the nasal mucosa and turbinates [3]. While most cases of epistaxis are minor, severe cases can obstruct the airway, obscure the view during intubation, and even lead to life-threatening situations [13]. Therefore, preventing epistaxis is crucial, and various methods have been studied to mitigate this complication by facilitating smoother passage of the tube through the nasal passages.
Common methods for reducing epistaxis include warming the TT, applying topical vasoconstrictors, and lubricating the TT [1,3,4]. Recently, several guide-based methods have been used to reduce epistaxis, each with its own advantages and limitations. Red rubber catheters significantly reduced moderate-to-severe epistaxis. However, this method often leads to longer intubation times and requires an additional step to remove the catheter orally [14,15]. The nasogastric tube method also effectively reduced epistaxis and improved the ease of navigation [16]. However, these results were based on studies involving adult patients, making it difficult to generalize the findings to pediatric patients. The use of suction catheters reduced epistaxis and improved the ease of navigation. However, the rigid and sharp tip of the suction catheter can cause nasal mucosal trauma during insertion, limiting its effectiveness in minimizing nasal bleeding [17].
The present study found that using the ETP as a guide offers several advantages over previous methods. The flexibility, small diameter, and soft tip of the ETP helps reduce resistance through the nasal passage and minimizes nasal trauma. Previous studies have demonstrated that resistance during nasotracheal intubation significantly increases the risk for epistaxis, with an incidence of 71% when resistance occurs compared with 12% without resistance [3,18]. The characteristics of the ETP enable smoother navigation through the nasal cavity. This approach may be especially beneficial for children, whose smaller and more delicate nasal passages are more susceptible to injuries.
The present study had some limitations. First, we did not use quantitative measures to assess the ease of navigation or the amount of epistaxis. These outcomes were subjectively evaluated by the practitioners and may have introduced variability. Second, we did not measure postoperative nasal pain, which is an essential aspect of patient comfort and satisfaction. The inclusion of standardized pain assessments in future investigations could provide a more comprehensive understanding of patient outcomes.
In summary, nasotracheal intubation guided by the ETP is an effective technique to facilitate smooth passage of the TT and reduce epistaxis in children. This technique should be encouraged for routine use during nasotracheal intubation in children due to its advantages, simplicity, and availability.
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