The use of a nasogastric tube to facilitate nasotracheal intubation: a randomised controlled trial

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1 Original Article doi: /anae The use of a nasogastric tube to facilitate nasotracheal intubation: a randomised controlled trial C.-W. Lim, 1 S.-W. Min, 2 C.-S. Kim, 2 J.-E. Chang, 3 J.-E. Park 1 and J.-Y. Hwang 4 1 Resident, Department of Anaesthesiology and Pain Medicine, Seoul National University Hospital, Seoul, Korea 2 Professor, 3 Fellow and 4 Assistant Professor, Department of Anaesthesiology and Pain Medicine, SMG-SNU Boramae Medical Center, Seoul, Korea Summary During nasotracheal intubation, the tracheal tube passes through either the upper or lower pathway in the nasal cavity, and it has been reported to be safer that the tracheal tube passes though the lower pathway, just below the inferior turbinate. We evaluated the use of a nasogastric tube as a guide to facilitate tracheal tube passage through the lower pathway, compared with the conventional technique (blind insertion of the tracheal tube into the nasal cavity). A total of 60 adult patients undergoing oral and maxillofacial surgery were included in the study. In 20 out of 30 patients (66.7%) with the nasogastric tube-guided technique, the tracheal tube passed through the lower pathway, compared with 8 out of 30 patients (26.7%) with the conventional technique (p = 0.004). Use of the nasogastric tube-guided technique reduced the incidence and severity of epistaxis (p = 0.027), improved navigability (p = 0.034) and required fewer manipulations (p = 0.001) than the conventional technique.... Correspondence to: J.-Y. Hwang mistyblue15@naver.com Accepted: 30 January 2014 Introduction In nasotracheal intubation, the tracheal tube passes through either the upper or the lower pathway in the nasal cavity [1]. The upper pathway is a passage between the middle and inferior turbinates, whereas the lower pathway lies along the nasal floor, underneath the inferior turbinate (Fig. 1). The middle turbinate is part of the ethmoid bone, which is a fragile, porous and vascular structure attached to the cribriform plate [2]. Moreover, it plays an important role in inspired airflow regulation, humidification and olfaction [2, 3]. Trauma to the middle turbinate may result in fracture, massive bleeding, cerebrospinal fluid rhinorrhea or olfactory nerve dysfunction [4, 5], and the lower pathway may be a safer passage for tracheal tube placement. However, a nasal preformed tracheal tube, even when thermosoftened, has been reported to be more likely than a flexible reinforced tube to pass through the upper pathway [1]. A nasogastric tube is a flexible plastic tube inserted through the nose into the stomach for feeding or administering drugs, or the drainage of gastric contents. In common with a reinforced tracheal tube, it may be likely to pass through the lower pathway when inserted into the nasal cavity [1]. Thus, we hypothesised that the placement of a preformed tracheal tube in the lower pathway could be facilitated by a nasogastric tube, acting as a soft and flexible guide, and compared the incidence of tracheal tube placement in the lower pathway and nasotracheal intubation-related 2014 The Association of Anaesthetists of Great Britain and Ireland 591

2 Lim et al. Nasogastric tube to facilitate nasotracheal intubation (a) (b) Figure 1 Pathways for nasotracheal intubation in the nasal cavity: (a) frontal view; (b) lateral view. complications of the nasogastric tube-guided technique with those of a conventional technique. Methods This study was approved by the Ethics Committee of our hospital. Written informed consent was obtained from all the patients. The trial was registered at the Clinical Research Information Service (KCT ). Adult patients undergoing oral and maxillofacial surgery requiring nasotracheal intubation were enrolled. Patients were not studied if they had a known or predicted difficult airway, oropharyngeal tumour, bleeding diathesis, a history of nasal trauma or basal skull fracture, or were at risk of aspiration. Patients were randomly allocated to one of the following two groups: nasotracheal intubation using a conventional technique (that is, blind insertion of the nasotracheal tube into the nasal cavity); or the nasogastric tube-guided technique. This was done using a computer-generated random number chart (Random Allocation Software, ver. 1.0; Isfahan University of Medical Sciences, Isfahan, Iran) with a block size of 4 and a 1:1 allocation ratio, by an investigator not clinically involved in the study. When patients were transferred to the operating room, assignments were determined using an opaque sealed envelope opened by another investigator with no clinical involvement in the study. Before anaesthesia, patients were instructed to compare their nasal airflow while alternately breathing through the right and left nostrils. The more patent nostril was chosen for nasotracheal intubation. If nasal patency was equal in both nostrils, we chose the nostril for intubation at random. Using a fibreoptic endoscope through the selected nostril, the presence of any intranasal abnormality was assessed. If there was an abnormality, the other nostril was examined and the more normal and patent one was used. No premedication was administered to the patient. Standard monitoring included electrocardiogram, pulse oximetry, gas analyser and non-invasive blood pressure monitoring. After pre-oxygenation with 100% oxygen, anaesthesia was induced using propofol 1.5 mg.kg 1, followed by rocuronium 0.6 mg.kg 1. During manual mask ventilation using sevoflurane 6 8% in 100% oxygen, two cotton swabs soaked in topical adrenaline 0.1% were applied to the nasal mucosa in the selected nostril for vasoconstriction. Internal diameter 7.0-mm and 6.5-mm nasal RAE tracheal tubes (Mallinckrodt Medical, Athlone, Ireland) were used for men and women, respectively. Thermosoftening of the tracheal tube was done by putting them into sterile isotonic saline maintained at 40 C. The tracheal tube was withdrawn from the saline bottle and lubricated with water-soluble jelly. The preformed tracheal tube was oriented with its concavity facing caudad for both techniques. With head extension, the conventional technique was performed by advancing the tube following the nasal floor to the posterior nasopharyngeal wall. In the nasogastric tube-guided technique, a lubricated nasogastric tube was inserted into the preformed tracheal tube (16 Fr for 6.5-mm tubes and 18 Fr for 7.0-mm tubes) and positioned with its tip protruding about 20 cm from the distal end of the tracheal tube (Fig. 2). The nasogastric tube was lubricated with water-soluble jelly and inserted into the nasal cavity along the floor of the nose in an attempt to advance it along the lower path The Association of Anaesthetists of Great Britain and Ireland

3 Lim et al. Nasogastric tube to facilitate nasotracheal intubation Anaesthesia 2014, 69, Figure 2 A nasal preformed tracheal tube with a nasogastric tube within it. way. After the nasogastric tube passed through the nose, the tracheal tube was advanced along the nasogastric tube, and then the nasogastric tube was retrieved from the nose. During tracheal tube insertion into the nasal pathway using both techniques, the tracheal tube was directed along the nasal floor in an attempt to advance it along the lower pathway (manipulation 1). If some resistance was encountered, the tracheal tube was redirected slightly more caudad (manipulation 2). If resistance was still felt, the tracheal tube was redirected slightly more cephalad in the nasal cavity (manipulation 3) [1]. If the tracheal tube could not be advanced in the nasal pathway, it was withdrawn and inserted into the other nostril in the same way. After the tracheal tube was advanced into the oropharynx, the severity of epistaxis was evaluated under direct laryngoscopy 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) [6]. Tracheal intubation was performed, if required, using Magill forceps. All intubations were performed by two anaesthesiologists. The number of manipulations and navigability through the nasal passage (defined as smooth, slight resistance or impinged) were recorded. The pathway taken by the tracheal tube was assessed using a fibreoptic endoscope alternately above and below the tracheal tube in the nostril. If the identification of the pathway was difficult, the patient was excluded from the study. In the recovery room, the presence of persistent nasal bleeding was evaluated. Nasal pain was graded using a 100- mm visual analogue scale. Our primary aim in this study was to compare the incidence of tracheal tube placement in the lower pathway. Secondary outcomes included the number of manipulations required, the incidence and severity of epistaxis, navigability during the tracheal tube insertion, and postoperative nasal pain and bleeding. A sample size calculation was performed using the Power Analysis and Sample Size software (2005, NCSS, Kaysville, UT, USA). According to a previous study in which the incidence of improper placement of the preformed tracheal tube in the nasal cavity was 80% [1], considering that a clinically significant reduction in improper tracheal tube placement was 40% in absolute terms, 28 patients were required for each group to achieve a significance level of 95% with a power of 80%. Thus, 31 patients per group were enrolled to compensate for possible dropouts. The SPSS software (ver. 20, IBM Inc., Armonk, NY, USA) was used for statistical analyses. The pathway in which the tracheal tube was placed, the number of manipulations, the severity of epistaxis and navigability during the tracheal tube insertion were compared using Fisher s exact test. A value of p < 0.05 was considered to indicate statistical significance. Results In total, we screened 70 patients between March and October Six patients did not meet the inclusion criteria and two patients declined to participate. The remaining 62 patients were randomly allocated, and two patients were then eliminated due to difficult intubation. Thus, data from 60 patients were analysed (Fig. 3). The tracheal tubes were inserted successfully through the selected nostril in all patients. Patients characteristics, selected nostril and anaesthetic time are presented in Table 1. The Magill forceps was used in 21 patients with the conventional technique and 19 patients with the nasogastric tube-guided technique (p = 0.785). In 20 out of 30 patients (66.7%) with the nasogastric tube-guided technique, the tracheal tube passed through the lower pathway, compared with 8 out of The Association of Anaesthetists of Great Britain and Ireland 593

4 Lim et al. Nasogastric tube to facilitate nasotracheal intubation Figure 3 Flow diagram for study. Table 1 Characteristics of patients undergoing nasotracheal intubations with either conventional or nasogastric tube-guided approaches. Values are number or median (IQR [range]). Conventional technique (n = 30) Nasogastric tube-guided technique (n = 30) Age; years 42 (30 57 [21 65]) 41 (27 60 [21 67]) Male/female 15/15 17/13 Weight; kg 62.9 ( [ ]) 67.2 ( [ ]) Height; cm ( [ ]) ( [ ]) ASA 1/2 21/9 23/7 Nostril (right/left) 15/15 17/13 Anaesthetic time; min 175 ( [ ]) 177 ( [ ]) patients (26.7%) with the conventional technique (p = 0.004). The use of the nasogastric tube-guided technique reduced the incidence and severity of epistaxis (p = 0.027), improved navigability (p = 0.034) and required fewer manipulations (p = 0.001) than the conventional technique (Table 2). Postoperative persistent bleeding and nasal pain were similar between the two groups (Table 2). Discussion This study has shown that the nasogastric tube-guided technique facilitated the passage of the tracheal tube through the lower nasal pathway and improved navigability with fewer manipulations, reducing the incidence and severity of epistaxis during nasotracheal intubation. Preformed nasal tubes are commonly used for nasotracheal intubation. However, it has been reported that they pass mainly through the upper pathway, even when thermosoftened [1]. In our study, the tracheal tube passed through the upper pathway in 73.3% of patients where the thermosoftened preformed tracheal tube was inserted using the conventional technique, consistent with a previous report [1]. However, when the preformed tracheal tube was inserted into the nasal cavity using a nasogastric tube, the tracheal tube passed through the lower pathway more frequently than with the conventional technique. It is assumed that the pliable and flexible nasogastric tube passed preferentially through the lower pathway. The previous study reported that the reinforced tracheal tube passed through the lower pathway more frequently than a The Association of Anaesthetists of Great Britain and Ireland

5 Lim et al. Nasogastric tube to facilitate nasotracheal intubation Anaesthesia 2014, 69, Table 2 Characteristics of nasotracheal intubations with either conventional or nasogastric tube-guided approaches. Values are number (proportion) or median (IQR [range]). Conventional technique (n = 30) Nasogastric tube-guided technique (n = 30) p value Pathway Upper 22 (73.3%) 10 (33.3%) Lower 8 (26.7%) 20 (66.7%) Navigability Smooth 14 (46.7%) 23 (76.7%) Slight resistance 10 (33.3%) 6 (20.0%) Impinged 6 (20.0%) 1 (3.3%) Epistaxis None 4 (13.3%) 14 (46.7%) Mild 13 (43.3%) 9 (30.0%) Moderate 11 (36.7%) 7 (23.3%) Severe 2 (6.7%) 0 (0.0%) Number of manipulations 1 10 (33.3%) 24 (80.0%) (40.0%) 5 (16.7%) 3 8 (26.7%) 1 (3.3%) Nasal pain (visual analogue score) 25 (20 40 [10 60]) 20 (10 30 [0 50]) Persistent nasal bleeding 5 (16.7%) 1 (3.3%) preformed tracheal tube due to the flexibility of the reinforced tracheal tube [1]. However, there are advantages of a preformed tracheal tube over the reinforced one for nasotracheal intubation. A preformed tracheal tube has a natural curvature, and thus it is easier to navigate the preformed tube from oropharynx into the laryngeal inlet. On the other hand, softer tracheal tubes such as reinforced ones tend to move along the posterior pharyngeal wall rather towards the laryngeal inlet, and it can be difficult to navigate them into the vocal cord without using Magill forceps [7]. Such use of Magill forceps may cause injury to the oropharyngeal mucosa [8] or the tracheal tube cuff [9]. For nasotracheal intubation, additional distance is required for proper positioning at the nares; the reinforced tube may be too short for nasotracheal intubation in some patients. Furthermore, although the preformed tracheal tube is designed to reduce kinking of the tube by a preformed curvature, the wire reinforcement does not extend to the proximal connector, and kinking may occur at this point [10]. In our study, the nasogastric tube-guided technique was advantageous because while a preformed tracheal tube passed through the nasopharynx, the nasogastric tube acted as a guide for the lower pathway; then, after retrieving the nasogastric tube, the preformed tracheal tube could easily be advanced towards the laryngeal inlet. Upon insertion of a nasogastric tube into one pathway, migration of the tracheal tube to another pathway might be prevented because the medial border of the inferior turbinate is close to the nasal septum. In patients with a large nasal cavity, the tracheal tube may not end up within one pathway, but between the two pathways. However, in our study, all tracheal tubes were observed within one of the two pathways, consistent with the previous study [1]. Nasotracheal intubation is required in patients undergoing head and neck surgery for surgical approaches, but it is more traumatic than orotracheal intubation [11]. The most common complication following nasotracheal intubation is epistaxis [12]. This results from nasopharyngeal mucosal injury or traumatic fracture when a rigid tracheal tube tip or a sharp-edged Murphy eye of a nasal preformed tracheal tube passes through the narrow passages [4, 5, 13]. Thus, smooth transit of the tracheal tube through the nasal passageway is essential to reduce the incidence of epistaxis [14]. Currently, thermosoftening [15], the use of vasoconstrictors [6, 16] and lubrication are widely used to reduce nasal bleeding following nasotracheal intubation. Several strategies have also been suggested to prevent epistaxis during nasotracheal intubation, including obturation of the tracheal tube [17], and using a nasopharyngeal airway [18] or a red rubber 2014 The Association of Anaesthetists of Great Britain and Ireland 595

6 Lim et al. Nasogastric tube to facilitate nasotracheal intubation catheter [19] as a guide. The use of an oesophageal stethoscope-obturated tracheal tube was effective in preventing epistaxis associated with nasotracheal intubation by obturating the Murphy-tipped tracheal tube [17]. In Enk et al. s study [18], the investigators inserted the tip of the tracheal tube into the trailing end of a red rubber nasopharyngeal airway and the tube was advanced under visual control to the oropharynx, guided by the airway. After the tracheal tube was observed in the oropharynx, the nasopharyngeal airway was disconnected and removed using Magill forceps. Using this method, the incidence and severity of nasal bleeding decreased significantly when compared with the control group. The use of a red rubber catheter has also been reported to guide a tracheal tube and reduce the severity of nasal bleeding in children [19]. A nasopharyngeal airway and a red rubber catheter act as a soft and flexible guide for the rigid tracheal tube, but they should be disconnected and withdrawn from the oropharynx with a Magill forceps. Thus, there are potential risks in disconnecting the nasotracheal tube or losing the guided nasopharyngeal airway or rubber catheter during intubation. In contrast, during a nasogastric tube-guided insertion, after a nasogastric tube is used as a guide, it is pulled back out of the nostril, and does not go further down the airway. In our study, using a nasogastric tube-guided insertion, the incidence and severity of epistaxis were reduced because the tracheal tube tends to pass through the lower pathway and the conventional, Murphy-tipped preformed tracheal tube was obturated with a nasogastric tube. Also, in this study, postoperative nasal pain was similar between the groups, although one might expect the use of nasogastric tube-guided technique to be less traumatic than the conventional technique. Possibly, the acute postoperative pain from the surgical procedures might have confounded the measurement of postoperative nasal pain. We acknowledge limitations to our study. First, the anaesthesiologists who performed the intubation were aware of the nasotracheal tube insertion technique. Second, the thermosoftened tracheal tube should be used immediately after withdrawal from the warm saline bottle to prevent stiffening on cooling; however, in the nasogastric tube-guided technique, a few seconds were required to insert a nasogastric tube into the thermosoftened tracheal tube. Nevertheless, the incidence and severity of epistaxis using the nasogastric tube-guided technique decreased significantly compared with the conventional group. In conclusion, using a nasogastric tube to guide a preformed tracheal tube through the nasal cavity improved both the placement of the tracheal tube in the lower pathway and the navigability, with fewer manipulations, reducing the incidence and severity of epistaxis. Competing interests No external funding and no competing interests declared. References 1. Ahmed-Nusrath A, Tong JL, Smith JE. Pathways through the nose for nasal intubation: a comparison of three endotracheal tubes. British Journal of Anaesthesia 2008; 100: Ogle OE, Weinstock RJ, Friedman E. Surgical anatomy of the nasal cavity and paranasal sinuses. Oral and Maxillofacial Surgery Clinics of North America 2012; 24: Lane AP. Nasal anatomy and physiology. Facial Plastic Surgery Clinics of North America 2004; 12: Moore DC. Middle turbinectomy: a complication of IMPROPER nasal intubation? Anesthesiology 2000; 92: Williams AR, Burt N, Warren T. Accidental middle turbinectomy: a complication of nasal intubation. 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