Nasotracheal intubation is an established airway management technique in patients undergoing throat and oral surgery. Narrow nasal passages and septal deviation occasionally complicate advancement of the nasotracheal tube. The rigid tube tip, with its sharp-edged Murphy eye, may increase the risk for nasopharyngeal injury. Accordingly, the nasal and pharyngeal mucosa is often traumatized, and severe bleeding occasionally occurs (1–3). Blood in the oropharynx reduces the view at laryngoscopy, which makes intubation more difficult.
Elwood et al. (4) reported a decrease in severity of nasopharyngeal bleeding when performing a catheter-guided nasotracheal intubation in children. However, the incidence of bleeding was not reduced with this maneuver.
Our hypothesis was that in adults, passage to the oropharynx can be facilitated by a Wendl tube (red rubber nasopharyngeal airway) acting as a soft and flexible ““pathfinder”” for the rigid endotracheal tube. Because the tip of the endotracheal tube (inner diameter [ID], 7.0 mm) fits exactly into the trailing end of the Wendl tube (28 Ch) and covers the Murphy eye almost completely, minimal tube contamination with blood and mucus is suggested. Accordingly, we performed a randomized, controlled trial with blinded assessment of nasopharyngeal bleeding and contamination of the tip of the endotracheal tube associated with the traditional and our “pathfinder” technique.
After approval by the institutional human investigation committee board and obtaining written, informed consent from all subjects, 60 patients, aged 20–60 yr, ASA grades I–II, who were scheduled for elective oral surgery, were enrolled in the study. Patients with a documented history of difficult intubation and those in whom physical examination suggested a potentially difficult airway or even indicated a need for awake intubation were excluded from the study. Additional exclusion criteria were any contraindications to nasotracheal intubation, such as abnormal coagulation status or recurrent epistaxis, gastroesophageal reflux requiring rapid-sequence induction, and latex allergy.
By drawing lots, patients were randomly allocated to one of the two study groups. In the control group (RAE;n = 30), conventional nasal intubation was performed with a RAE™ tube (ID, 7.0 mm; Mallinckrodt Medical, Athlone, Ireland). Patients in the treatment group (RAE + Wendl;n = 30) were intubated with a RAE™ tube guided by a Wendl tube (red rubber nasopharyngeal airway with an adjustable flange; 28 Ch; Willy Rüsch AG, Kernen, Germany;Fig. 1).
Before anesthesia, the patients were instructed to compare their nasal airflow while alternately breathing through the right and left nostril. The considered nostril was chosen for nasotracheal intubation.
Anesthetics were standardized for all patients. After premedication with clorazepate (0.3 mg/kg) and the administration of a local vasoconstrictor (0.3 mL of oxymetazoline 0.05%) in the operating room, general anesthesia was induced with thiopental (5 mg/kg), sufentanil (0.4 μg/kg), and 5% desflurane. To guarantee sufficient relaxation, rocuronium (0.6 mg/kg) was administered. After the induction of general anesthesia, a Wendl tube was lubricated with approximately 0.5 mL of lidocaine 2% gel and inserted into the more patent nostril.
In the control group, the Wendl tube was retrieved from the nose before passage to the oropharynx was attempted with the RAE™ tube. To standardize the intubation, all anesthesiologists were instructed to avoid any possibly helpful maneuver (e.g., rotation of the endotracheal tube). In the treatment group, the Wendl tube was kept in position, and only its adjustable flange was removed. Afterward, we inserted the tip of the endotracheal tube into the trailing end of the Wendl tube. Subsequently, the rigid RAE™ tube was advanced under visual control to the oropharynx, guided by the soft and flexible Wendl tube. As soon as the endotracheal tube was observed in the oropharynx, the Wendl tube was disconnected and removed with Magill forceps. Ease of nasal passage and retrieval of the “pathfinder” were evaluated by the anesthesiologist assigned to the case, according to the following classification system: 1, easy; 2, medium; 3, difficult; 4, impossible.
An anesthesiologist not aware of the procedure remained outside the room until the endotracheal tube was positioned in the oropharynx and the Wendl tube was removed. Then, contamination of the tube tip with blood and mucus was graded immediately, and the blood detected in the oropharynx was classified by this blinded observer: 1, no blood or mucus; 2, some blood or mucus; 3, a lot of blood or mucus.
In both groups, intubation was finally completed during direct laryngoscopy. A Magill forceps was used to help the endotracheal tube pass the glottis, if required. Throughout the operation, anesthesia was maintained with 4%–6% desflurane in an oxygen/air mixture and repeated administration of sufentanil (0.1 μg/kg), if clinically indicated.
Throughout the study, intubations were performed by four experienced residents with practical and theoretical skills in nasotracheal intubation. A staff anesthesiologist served as the same blinded observer in all cases.
In the postoperative anesthesia care unit, patients received 0.1 mg/kg of piritramide, if required. Six hours after surgery, an anesthesiologist blinded to the study design asked the patients to rate their nasal pain with a visual analog scale (0, no pain; 10, most severe pain).
For statistical analysis, SigmaStat 2.03 software (SPSS Inc., Chicago, IL) was used. Ordinal end points were compared by using the Mann-Whitney U-test, proportions by using the χ2 test, and continuous end points by using Student’s t-test. For all tests, P < 0.05 was considered to be statistically significant. Data are expressed as median (25th and 75th percentile), number, or mean ± sem, as appropriate.
We studied 60 patients. There were no significant differences in demographic data for the two study groups with respect to age, sex, weight, height, ASA status (Table 1), perioperative prescription of nonsteroidal antiinflammatory drugs, or opioids administered in the postoperative anesthesia care unit.
Nasopharyngeal passage of the endotracheal tube was initially impossible in four patients in the control group. These patients were successfully intubated with the “pathfinder” technique, according to the procedure of the treatment group. For this reason, these patients had to be excluded from evaluation of contamination of the tube tip, pharyngeal bleeding, and nasal pain score. In the treatment group, no problems occurred during nasopharyngeal passage, and nasotracheal passage was successful on the first attempt.
Intubation with the Wendl-guided technique facilitated nasal passage (P = 0.004). The incidence (P < 0.001) and severity (P = 0.001) of bleeding, as well as postoperative nasal pain (P = 0.036), were clearly diminished in the treatment group. Tube contamination with blood and mucus was significantly decreased (P < 0.001 each) (Table 2). Retrieval of the Wendl tube was judged as easy (1 [1; 2]) by all anesthesiologists. No case of cuff damage after intubation was noted. No patient experienced epistaxis in the postanesthesia care unit or on the ward.
The major finding of our study was that there was less bleeding and minimal tube contamination during nasopharyngeal passage in the intervention group. Typical complications associated with nasotracheal intubation are nosebleeds, which result from lesions of the nasal and/or pharyngeal mucosa caused by the rigid tip or the sharp-edged Murphy eye of conventional endotracheal tubes (1–3). Blind nasal passage can lead to partial excision of nasal mucous membranes and even of a turbinate (5). The topography of the nasopharynx forces the advancing endotracheal tube to bend sharply and increases the risk of a submucosal via falsa, possibly progressing to a retropharyngeal abscess (6).
Before this study, we tried to minimize nasopharyngeal trauma in accordance with published recommendations (7,8). Thus, all our patients received vasoconstrictors in the nostrils before nasotracheal intubation was attempted. We consequently identified the more patent nostril by comparing airflow (9). Furthermore, we always dilated the identified nostril by inserting a Wendl tube temporarily. Lidocaine 2% gel was applied to the Wendl tube to protect nasal mucous membranes and to reduce postoperative nasal pain. Nevertheless, we still noted a considerable frequency of particularly troublesome nosebleeds that required repeated topical administration of vasoconstrictors. However, the patients already felt comfortable with that procedure of nasotracheal intubation (see the visual analog scale score for nasal pain in the control group;Table 2).
A soft and flexible nasopharyngeal airway traverses the nasopharynx atraumatically (10) and finds the best way to the oropharynx, typically along the floor of the nasal cavity. The trailing end of the 28-Ch Wendl tube (outer diameter, 9.3 mm; ID, 6.9 mm) exactly fits the tip of the RAE™ tube (ID, 7.0 mm). Thus, we speculated on minimizing nasopharyngeal trauma by using this tube assembly, which is characterized by a soft and flexible front part that acts as a “pathfinder” for the more rigid back part.
Because the sharp-edged Murphy eye is covered almost completely by the Wendl tube, we also expected a reduction of blood and mucus contamination of the tip and the lumen of the endotracheal tube. The “pathfinder” technique proved to be of clinical relevance. It facilitates nasopharyngeal passage of the endotracheal tube and reduces nasopharyngeal bleeding and postoperative nasal pain. We also found a remarkably reduced contamination of the tube tip and the inner lumen of the endotracheal tube.
Because of the increasing risk of nasal and/or pharyngeal trauma, the anesthesiologist assigned to the case was instructed to exert only moderate force during nasopharyngeal passage. This might explain why nasopharyngeal passage was initially impossible in four patients of the control group and why we did not observe any case of persistent nosebleeds in our study.
Our “pathfinder” technique can be considered as a modification of a previously described procedure, in which a 16F Jacques red rubber catheter was used for nasopharyngeal passage of an endotracheal tube (11). The only prospective evaluation of this technique was performed in children (4). The authors of this recently published investigation reported a decrease in severity of nasopharyngeal bleeding when a catheter-guided nasotracheal intubation with an endotracheal tube softened with warm water was performed. However, the incidence of bleeding could not be reduced. The incidence and severity of bleeding were determined by swabbing the posterior pharynx with a folded 4 × 4 in. gauze and Magill forceps immediately after intubation. Subsequently, a blinded observer inspected the gauze for blood and tissue. This method might be more sensitive to detect discrete bleeding than sole inspection of the tube tip and the oropharynx, as we did in our study. However, children are not “little adults.” To pass the nasopharynx of a child atraumatically is challenging because of the vulnerable mucous membrane. For this reason, we think that our data obtained in adults should not be compared with the data of Elwood et al. (4).
One can speculate whether a red rubber catheter (11) or a Wendl tube provides the better guide for the nasotracheal tube. A 16F catheter intended for single catheterization of an adult’s bladder has an outer diameter of 5.33 mm, whereas a 28-Ch Wendl tube measures 9.3 mm. The smaller catheter may enter the passage between the middle and inferior turbinate (middle meatus), which is typically narrower compared with the larger passage between the inferior turbinate and the nasal surface of the palate (inferior meatus) (8). However, it is more likely that the larger Wendl tube finds the best way through the nasal cavity. In addition, the larger Wendl tube may dilate the nasal passage more effectively, indicating that the use of a Wendl tube seems to be more favorable.
Although our technique provides advantages compared with the traditional procedure, we emphasize that the endotracheal tube should never be drawn back after the Wendl tube has disappeared into the nostril, because this may lead to disconnection of the Wendl tube from the tip of the endotracheal tube during nasal passage. With the Wendl tube still in the nose, advancing the guideless endotracheal tube negates the advantages of the technique. The best guidance for nasopharyngeal passage of smaller-sized endotracheal tubes must be established by using smaller-sized Wendl tubes that snugly fit the tip of the endotracheal tube.
Typically, the Wendl tube creases in the hypopharynx; less frequently, it enters the esophagus. Rarely, the tip of the Wendl tube passes through the glottis, as can be expected because of the topography of the hypopharynx. There is a potential risk of losing the Wendl tube if the endotracheal tube is advanced blindly. Therefore, the Wendl tube must be identified in the oropharynx before nasal passage of the endotracheal tube is attempted. However, if losing the Wendl tube is still a concern, one may use Magill forceps to bring the tip of the Wendl tube out of the patient’s mouth before completing nasopharyngeal passage. This modification of the technique used in our study minimizes the risk. After this study, we performed the “pathfinder” technique in approximately 400 patients, and none of the Wendl tubes became a foreign body. Provided that this technique is performed correctly, it is safe.
Use of a green-colored nasopharyngeal airway (Willy Rüsch AG) would facilitate recognition of the tube in the pharynx. This device is made of a latex-free material (Wirupren™), and hence the “pathfinder” technique can be used even in patients with latex allergy.
Our technique is less expensive compared with an esophageal stethoscope (12) or an intraluminal balloon (1) used as obturators of the endotracheal tube. In addition, inevitable contamination of the inner lumen by retraction of such devices or a suction catheter (used as a guide) can be avoided.
The significantly reduced tube contamination in our study might be associated with a decreased risk of airway infections, especially in patients with multimorbidity and immunodeficiency. Although our study does not provide any data for this hypothesis, it is clinical pragmatism to avoid or at least minimize contamination of the endotracheal tube whenever possible.
Because thermosoftening of the endotracheal tube with warm saline reduces epistaxis and nasal damage (3), further improvement of the “pathfinder” technique seems possible. However, our main concern must be primum nihil nocere. For this reason, it is advisable to make any effort to reduce nasopharyngeal trauma.
The authors thank N. Jeffery and T. Roe (Department for Cranio-Maxillofacial Surgery, University of Münster, Münster, Germany) for helpful critical review of the manuscript.