2. Materials and Methods
nasal bleeding, epistaxis, oropharyngeal tumor, fracture, ’s loss of consciousness, glottis, nasal airflow, nasal pain, abnormal coagulopathy, nasal trauma
NASAL BLEEDING, AIDS, SECONDARY, CAVITY, EPISTAXIS, BENDING
The study protocol was approved by the Institutional Review Board of Chonnam National University Hospital (CNUH-2020-242), and registered in the Clinical Research Information Service of the Korea National Institute of Health in the Republic of Korea (KCT0005987), which belongs to the World Health Organization Registry Network. Written informed consent was obtained from all the patients. Adult patients who were scheduled to undergo oral and maxillofacial surgery requiring nasotracheal intubation were included in the study. Patients with an American Society of Anesthesiologists (ASA) physical status >III, age <20 years, body mass index (BMI) ≥ 35, abnormal coagulopathy, oropharyngeal tumor, a known or predicted difficult airway, a history of nasal trauma, and previous basal skull fracture or surgery were excluded. The enrolled patients were randomly allocated to either the NG (nasogastric) group or SC (suction catheter) group, using a computer-generated randomization code; the allocation rate was 1:1. Pre-operatively, an airway examination was performed, including determining Mallampati grade (I–IV), mouth opening limitation, neck extension limitation, nasal or oral anatomical abnormalities, neck circumference, and thyromental distance. The nostrils were selected by examining the patient’s obstructive symptom and nasal airflow when breathing through the right and left nostrils alternately. Before the patient entered the operating room, the intubating equipment for each group was prepared which included Polar™ Preformed Tracheal Tubes (Smith Medical, Dublin, OH, USA), a Nasogastric Tube (12Fr, Yushin medical, Bucheon, Republic of Korea), or the Mallinckrodt Broncho-Cath Kit Suction Catheter (10Fr, Mallinckrodt, Raleigh, NC, USA). The preformed nasotracheal tube was initially selected based on gender (internal diameter 6.5 mm for females and 7.0 mm for males). When the patient arrived at the operating room, by comparing the diameter of the patient’s nostrils and the tube, a 0.5 mm smaller tube was prepared if the diameter of the nostril was small.The patient was not administered pre-medication before entering the operating room. In the operating room, standard intraoperative monitoring equipment, such as electrocardiogram, pulse oximetry, non-invasive blood pressure measurement, and capnography were applied to all patients. All patients took the sniffing posture in the supine position. The height of the bed was adjusted so that the patient’s head was positioned between the intubator’s umbilicus and the epigastrium. Patients were preoxygenated with 100% oxygen at 3 min. General anesthesia was induced with propofol at 1.5~2.0 mg/kg, and 0.1~1.0 mcg/kg/min of remifentanil was injected according to the patient’s hemodynamic response. When the patient’s loss of consciousness was confirmed, 0.6 mg/kg of rocuronium was injected to facilitate intubation. In each group, a nasogastric tube or a suction catheter coated with water-soluble jelly was placed in a preformed nasotracheal tube lubricated with water-soluble jelly. If the guiding device is too long, it is difficult to remove it, and if it is too short, there is a possibility that the tube cannot be guided. As shown in The nasogastric tube or suction catheter together with the preformed nasotracheal tube was inserted into the nostril, and entered along the nasal floor toward the posterior nasopharyngeal wall. Once the suction catheter or the nasogastric tube passed through the nasal cavity to the vocal cord, the preformed nasotracheal tube was introduced into the nasal cavity through the guidance tool, and the guiding suction catheter or nasogastric tube was removed. The preformed nasotracheal tube was then intubated to the trachea through a direct laryngoscope. If necessary, the tube was introduced into the glottic inlet using Magill forceps. Proper intubation was confirmed by inflating the nasotracheal tube cuff, auscultation, and continuous monitoring of the end-tidal COThe number of manipulations during intubation in the nasal cavity was measured using the following method. During intubation, a preformed nasotracheal tube was first inserted into the lower pathway (1st manipulation). If the nasotracheal tube could not enter due to resistance, the tube was redirected more caudally (2nd manipulation). If the tube still could not enter, it was slightly redirected in the cephalic direction (3rd manipulation). When the first intubation failed, intubation was attempted through the other nostril in the same way. Each insertion attempt was recorded. Moreover, the navigability (smooth, resistance, obstructed) required to insert the tube into the oropharynx from the nasal cavity was recorded. After a preformed nasotracheal tube entered the oropharynx, the degree of nasal bleeding was evaluated through a direct laryngoscope using a 4-point scale (no epistaxis; mild epistaxis: blood on the tracheal tube only; moderate epistaxis: blood pooling in the pharynx; or severe epistaxis: blood in the pharynx sufficient to impede intubation. The use of the Magill forceps, neck extension, tube rotation, backward, upward, and rightward pressure (BURP) manipulation, and Cormack grading of the glottis during direct laryngoscope insertion of the tube into the trachea were documented.The insertion time from the nostril to the oropharynx and total intubation time were calculated by recording the time when the tip of the nasogastric tube or suction catheter began to be inserted into the nostril, the time when the tip of the nasotracheal tube entered the oropharynx, and the time when the first end-tidal COThe primary outcome of this study was the total intubation time. The secondary outcomes were the degree of nasal bleeding at intubation through a direct laryngoscope, the number of manipulations in the nasal cavity, navigability, the use of Magill forceps, nasotracheal tube pathway in the nasal cavity, nasal pain, and persistent epistaxis at PACU.The possibility that physical characteristics such as bending deformation of the suction catheter and nasogastric tube may affect tube guidance was also considered. Accordingly, an investigation of this variable at Chonnam National University Engineering Practice Education Center was requested. A stress relaxation test was performed as the 3-point bending test using the DMA 2980 Dynamic Mechanical Analyzer. The relaxation modulus was measured for 10 min while applying 0.1% strain (change in shape and volume that occurs when an object is subjected to an external force) at 35 ℃ to the suction catheter and the nasogastric tube, respectively. The force applied while removing the aids from the preformed nasotracheal tube was also assessed. The force was measured 5 times for each preformed nasotracheal tube-guiding device combination. Three different sizes (6.00 mm, 6.5 mm, and 7.00 mm) of the nasotracheal tube were tested.The sample size was calculated by measuring the total time required for tracheal intubation in a pilot study. The total time for tracheal intubation under suction catheter guidance was 53.73 ± 16.43 s, and under nasogastric tube guidance was 62.6 ± 15.09 s. Using G*Power 3.1.9.4, the sample size of 51 patients per group was calculated for 80% power and α-error of 5% (two-tailed test). Considering a dropout rate of 10%, it was calculated that 57 patients per group, and a total of 114 patients, were needed. SPSS for Windows ver. 21.0 (SPSS Inc., Chicago, IL, USA) was used for statistical analysis. The Shapiro–Wilk test was performed to examine the assumption of normality. Student’s 