Asymptomatic intranasal abnormalities influencing the choice of nostril for nasotracheal intubation

Transcription

1 British Journal of Anaesthesia 83 (6): (1999) Asymptomatic intranasal abnormalities influencing the choice of nostril for nasotracheal intubation J. E. Smith 1 * and A. P. Reid 2 1 Department of Anaesthesia and 2 Department of Otolaryngology, University Hospital Birmingham, Selly Oak Hospital, Birmingham B29 6JD, UK ^Corresponding author We have studied the prevalence of intranasal abnormalities that may influence the choice of nostril for intubation, using the fibreoptic laryngoscope, in 60 oral surgery patients presenting for nasotracheal intubation under general anaesthesia, who had no symptoms or signs of nasal obstruction. Videotape recordings were made during each nasendoscopy and later analysed by an anaesthetist and an otolaryngologist. A total of 68% of patients had intranasal abnormalities (10% bilateral and 58% unilateral) which resulted in one nostril being more patent than the other and therefore considered more suitable for intubation. The most common abnormality was deviated nasal septum which occurred in 57% of the study group; 22% were minor deviations, 13% were major deviations and 22% were impactions. Other abnormalities were simple spurs, unilateral polyp and hypertrophy of the inferior turbinate. In view of the relatively high incidence of intranasal pathology revealed on endoscopic examination, anaesthetists should consider using the fibreoptic laryngoscope to select the best nostril when performing nasotracheal intubation. BrJAnaesth 1999; 83:882-6 Keywords: intubation nasotracheal, complications; complications, nasal abnormalities Accepted for publication: July 9, 1999 Nasotracheal intubation may sometimes cause nasal reduce the frequency of nasal injury. Unfortunately, a trauma. 1 The most frequent complication is epistaxis, which characteristic feature of many septal deviations is that they may occasionally be troublesome, even when vasoconstric- do not disturb nasal function appreciably and therefore the' tors, a smaller, softened, well-lubricated tube and careful nostrils seem equally patent to the patient. 7 Hence there manipulations are used. More seriously, there have been may be few clinical signs and no history of the deformity reports of partial and even total avulsions of middle and which means that it may be difficult to diagnose at the inferior turbinates. 2 " 5 More rarely, an amputated turbinate preoperative visit. may obstruct the nasotracheal tube, further jeopardizing Fibreoptic endoscopy of the nasal cavities is a good way patient safety. 6 of assessing nasal anatomy and this procedure is used Pre-existing nasal pathology may render the nose more widely as a diagnostic tool in otolaryngology clinics, susceptible to trauma during nasal intubation. It is therefore However, there are no reports of the use of this technique essential to enquire specifically about symptoms related to to assess the nostrils before nasotracheal intubation, nasal function and to assess the patency of each nostril Nasendoscopy may be helpful in the selection of the more in patients requiring this type of intubation. Intranasal patent nostril in patients with asymptomatic unilateral nasal abnormalities may be bilateral or unilateral and may produce pathology and it might also identify which nostril is least a significant degree of nasal obstruction which impedes affected, if any, in bilateral nasal pathology. However, passage of the tracheal tube to a greater or lesser extent, before this examination can be recommended as a routine For example, the presence of nasal polyps may result in procedure before nasotracheal intubation, it would be useful bilateral nasal obstruction whereas deviation of the nasal to establish the incidence of unsuspected nasal abnormseptum or a unilateral septal spur may result in unilateral alities. It would also be useful to know the causes and obstruction. Septal deviations are believed to be extremely to estimate the severity of unilateral and bilateral nasal common 7 whereas nasal polyps are less common. It is obstruction in this group of patients, therefore possible that the incidence of unilateral obstruction This observational study was designed to identify the is higher than that of bilateral obstruction. If this were the prevalence of normal and abnormal nasal anatomy in case, selection of the most patent nostril for intubation may asymptomatic oral surgery patients presenting for naso- British Journal of Anaesthesia

2 Choice of nostril for nasotracheal intubation tracheal intubation using the fibreoptic laryngoscope. We determined how often one nostril was considered more suitable for intubation than the other and specified the reasons why particular nostrils were preferred. In particular we attempted to identify abnormalities that might be expected to predispose patients to a significantly higher risk of severe injury if excessive force was used to intubate the abnormal nostril. Inferior turbinate Floor of Pathway 1 Pathway 2 Nasal nose airspace I Fibrescope Patients and methods The study was approved by the South Birmingham Local Research Ethics Committee and all patients gave informed, written consent. We studied 60 consecutive patients requiring nasotracheal intubation for elective oral surgery under.general anaesthesia. They were ASA I or II, aged yr, not morbidly obese and with no history of oesophageal reflux. Each patient was asked the following questions to determine their suitability for the study: (1) Do you have any difficulty in breathing through your nose? (2) Can you breathe clearly through both nostrils? (3) Can you breathe equally through both nostrils or is one nostril clearer than the other? Only patients who reported being able to breathe easily and equally through both nostrils were studied. The patency of both nostrils was confirmed by palpating the passage of air through each nostril during expiration when the contralateral nostril was occluded. Any patient with a history of nasal obstruction or nasal trauma was excluded. Approximately 30 min before and then approximately 5 min before induction of anaesthesia, two sprays of xylometazoline were applied to the nasal mucosa of each nostril with a Rogers Crystal Spray as the patient inhaled. Electrocardiogram, indirect arterial pressure, arterial oxygen saturation and carbon dioxide concentrations were monitored. Glycopyrrolate jug was administered i.v. and patients were treated with 100% oxygen. Anaesthesia was induced with fentanyl 1 (ag kg" 1 and propofol 2.5 mg kg" 1 followed by atracurium 0.5 mg kg" 1, and the patient's lungs were ventilated with isoflurane in oxygen using a face mask attached to a Bain system until neuromuscular block was complete. Each nostril in turn was examined with an Olympus LF2 fibreoptic laryngoscope (diameter 4 mm) attached to an endoscopic video camera system and a videotape recorder. Videotape recordings of the endoscopies were made following General Medical Council guidelines. Initially the endoscopic views at anterior rhinoscopy were compared, and then the posterior parts of both nasal cavities were examined. The fibrescope was passed both underneath and alongside the inferior turbinate in each nostril and any resistance to the passage of the instrument along these two pathways was noted (Fig. 1). Finally, fibrescope-guided nasotracheal intubation was performed through the most patent nostril and subsequently anaesthesia and surgery proceeded normally. The videotape recordings were later analysed by an Middle turbinate' Superior turbinate Septum Fig 1 Diagrammatic coronal section through the mid-nose showing the two main pathways for nasal endoscopy. The endoscopist is standing behind the head of the supine patient, so the floor of the nose is seen at the top of the visual field. Most of the airspace in the nasal cavity is near the floor of the nose, so the floor of the nose is the most important landmark which should be identified during every endoscopy. Pathway 1 lies along the floor of the nose, underneath the inferior turbinate, from the base of the septum laterally. Pathway 2 lies alongside the inferior turbinate, between the inferior turbinate and the septum. In this position, the view of the floor of the nose is often lost in mid-cavity, but usually the lower edge of the middle turbinate appears at the bottom of the visual field and the fibrescope advances along the lower border of this structure. anaesthetist and otolaryngologist. Nasal abnormalities were classified as follows 7 : (1) Simple spurs-sharp angulations of the septum which usually occurred at the junction of the vomer below and the septal cartilage above. A simple spur did not impact with the lateral wall of the nose. (2) Deviations-more generalized lateral displacements of the septum, when the septum bulged into the nostril and significantly reduced the size of the ipsilateral nasal cavity. They were ' C- or 'S'-shaped, in the vertical or the horizontal plane, and usually involved both cartilage and bone. (3) Other pathological features, for example hypertrophy of the turbinates, polyps, septal perforations, tumours, etc. Septal deviations were further classified as follows: (1) No septal deviation-symmetrical, equal-sized nostrils. (2) Minor septal deviation-a lateral deflection which significantly reduced the size of the nasal cavity but did not obstruct the passage of the fibrescope. (3) Major septal deviation-which did obstruct the passage of the fibrescope. (4), defined as a marked angulation of the septum with a spur which lay in contact with the lateral wall of the nose. 883

3 Smith and Reid The number of noses where one nostril was more patent and considered more suitable for intubation than the other nostril, and the reasons why the particular nostril was preferred were recorded. An assessment was made of the number of noses in which anatomical anomalies in one nostril were considered to expose the patient to a significantly higher risk of serious nasal injury, if the abnormal nostril had been intubated. Results Patient characteristics are shown in Table 1. The majority of patients were undergoing either surgical excision of impacted third molar teeth or dental extractions. Seven patients who gave a history of unilateral nasal obstruction on the preoperative visit and one patient who was noted to have a blocked nostril on clinical examination were not studied. The videotape review of the 60 endoscopies by an otolaryngologist and an anaesthetist confirmed that at the time of endoscopy, the anaesthetist had correctly selected the best nostril for intubation in all noses where one nostril was more suitable than the other; 41 (68%) patients had intranasal abnormalities that resulted in one nostril being more patent than the other, and therefore more suitable for intubation, rather than noses with equally patent nostrils (32%) (Table 2). Thirty-five (58%) patients had unilateral abnormalities and six (10%) had bilateral abnormalities (Table 2). In each of the six patients with bilateral abnormalities, one nostril was considered to be less severely affected than the other, so a preferred nostril was still identified. Three of the bilateral abnormalities were the result of an S-shaped septum in the horizontal plane. Further details of the six patients with bilateral abnormalities are given in Table 3. In the majority of the 41 patients with intranasal abnormalities, access through the nostrils was impeded by the presence of a deviated nasal septum. In other patients, simple spurs, hypertrophy of the inferior turbinate and a unilateral nasal polyp restricted free passage (Table 2). Table 4 shows the prevalence of the three types of septal deviation in the 60 patients (in patients with S-shaped septa, the predominant deviation only is given). More nasal septa were deviated to the left than to the right (21 vs 13) but this was not statistically significant (Fisher's exact test). As might be expected, endoscopies performed on nasal cavities with any of the three types of septal deviation were technically more difficult than those performed on normal nasal cavities. However, simple spurs and hypertrophies of the inferior turbinate did not usually complicate the performance of endoscopy. Thirteen patients had impacting spurs and 10 patients had simple (non-impacting) spurs. Four simple spurs were considered to reduce the patency of the nostril to such an extent that the other nostril was preferred for intubation. Of the remaining simple spurs, five were associated with septal deviations and the sixth was associated with a nasal Table 1 Patient characteristics (mean (SD or range) or number) No. Age (yr) Weight (kg) Sex (F/M) Scheduled surgery (16-57) 69.0 (16.1) 37/23 Excision of impacted third molar teeth, 44 Dental extractions, 9 Other, 7 Table 2 Number (%) of patients considered to have equally suitable nostrils lor intubation and number (%) who had a more patent nostril and therefore a preferred nostril for intubation. The number (%) of each type of obstructive abnormality is given [95% confidence intervals] Nostrils equally suitable One nostril preferred Main reasons for preference Unilateral abnormality Bilateral abnormality Total Septal deviation Simple spur Polyp Inferior turbinate hypertrophy 19 (32) [20-44] 35 (58) [ ] 6 (10) 41 (68) [ ] [56-80] 34 (57) [ ] 4(7) 1 (2) 2(3) Table 3 Details of each nostril in patients with bilateral intranasal abnormalities Patient No. Abnormality Preferred nostril Comment nostril Right nostril Minor deviation Major deviation Major deviation Large polyp Minor deviation Right S-shaped septum S-shaped septum S-shaped septum. Pathway alongside left inferior turbinate was clear 884

4 Choice of nostril for nasotracheal intubation polyp. These six spurs were not considered to be the decisive factors in the choice of nostril for intubation. The initial anterior rhinoscopy successfully selected the best nostril for intubation in 55 patients (92%). However, in five patients (8%), anterior rhinoscopy alone was misleading as significant abnormalities, including impactions and major deviations, were revealed only when the posterior parts of the noses were examined. Patients with impactions (13), major septal deviations (eight) and a unilateral nasal polyp (one) represented 37% of the study group and were considered to have deformities which might have rendered them more vulnerable to significant nasal trauma if the abnormal nostril had been intubated with excessive force. The two pathways through each nostril (Fig. 1) were examined in 60 patients. In 30 of these 240 pathways, passage of a 4-mm diameter fibrescope was impeded, as shown in Table 5. Sixteen patients had one pathway blocked, four had two pathways blocked and two had three pathways blocked. Of the two patients who had three pathways blocked, the clear pathway was underneath the inferior turbinate in one patient and alongside the inferior turbinate in the other. Discussion We have demonstrated that a relatively high proportion of oral surgery patients presenting for nasotracheal intubation have significant intranasal deformities, even though they give no history of nasal obstruction and when both nostrils appear patent on clinical examination. We also demonstrated that it is possible for anaesthetists to select accurately and consistently the best nostril for intubation, when one nostril is more suitable than the other. As 68% of patients had one nostril that was considered to be more patent and more suitable for intubation than the other on endoscopic examination, we suggest that preliminary nasendoscopy before intubation may have a role in the anaesthetic assessment and management of maxillofacial patients. It is important to emphasize however that our study did not determine if selecting nostrils with the fibrescope resulted in less trauma Table 4 Number (%) of patients with the three types of septal deviation [95% confidence intervals] No deviation 26 (43) [ ] Minor septal deviation 13 (22) [ ] Major septal deviation 8(13) [ ] s 13 (22) [ ] to nasal tissues than traditional Macintosh intubation, and we do not present evidence to support or refute this hypothesis. Further studies are required to investigate if selecting nostrils endoscopically significantly reduces the morbidity associated with this type of intubation. The study was designed to detect obstruction caused by the bony skeleton of the nose rather than that caused by congestion of mucous membranes as a result of the nasal cycle. The nasal cycle is the physiological variation in nasal airway patency seen in normal individuals. 8 It is caused by engorgement of the turbinates and occurs in an alternating cycle on each side of the nose up to five or six times each day. We temporarily abolished this cycle in our participants by administering a vasoconstrictor (xylometazoline) to the nasal mucosa. Nasal septal deviation is known to be an extremely common condition, 7 particularly in the leptorrhine (Greek, long and narrow) type of nose found in Caucasians, and it was the most frequent abnormality found in our study. In many patients, septal deviations are asymptomatic and the individual is unaware of their presence. They do not appear to disturb nasal function appreciably and do not require surgical treatment. One situation where septal deviations may cause problems is during nasal intubation. Minor septal deviations, as defined in this study, are unlikely to be associated with serious nasal trauma. Major deviations, where passage of a 4-mm diameter fibrescope is prevented, or impactions where an angulated septum and spur lie in contact with the lateral nasal wall were present in 35% of our patients. It is conceivable that these may be associated with an increased risk of significant nasal injury if excessive force is used to advance the tracheal tube through the affected nostril. It is remarkable that patients with these major abnormalities do not sustain injuries more frequently during Macintosh intubation where the anaesthetist is blind to the anatomical features of the nasal cavities. One explanation may be that with experience, anaesthetists develop an acute sense of how much pressure they can exert safely on the tracheal tube. As they approach this threshold pressure, they abandon that side of the nose and try the other side. It is possible however that miscalculations will occur, even in the most skilful hands. A technique that enables rapid, reliable and safe identification of nasal abnormalities before intubation is preferable to one that relies on trial and error. However, it is important to emphasize that the diagnosis of nasal abnormalities is a new aspect of fibreoptic endoscopy for most anaesthetists, and therefore as in learning any new skill, practice and experience are required for consistent success. Table 5 Number of times advancement of the fibrescope was blocked along the two pathways through each nostril in the 60 patients Right nostril pathways nostril pathways Underneath inferior turbinate (pathway 1) Alongside inferior turbinate (pathway 2) Underneath inferior turbinate (pathway 1) Alongside inferior turbinate (pathway 2) 885

5 Smith and Reid Septal deviations may be the result of direct trauma to the nose but Gray 9 believes that most cases are explained by the birth moulding theory. Abnormal intrauterine posture may result in compressive forces acting on the nose and maxilla. Further displacement may occur during parturition after which subsequent growth of the nose accentuates the asymmetries. Moulding pressures are believed to be most severe in persistent occipitoposterior positions, less severe in occipitoanterior positions and minimal in elective Caesarean section deliveries. However, recent studies by Harkavy and Scanlon, 10 Hartikainen-Sorri and colleagues 11 and Kent and colleagues have questioned the validity of the birth moulding theory. The initial endoscopic anterior rhinoscopy gave an accurate indication of the most patent nostril in the majority of cases. However, in five (8%) patients, anterior rhinoscopy was misleading because of abnormalities in the posterior nasal cavity. Hence when one nostril appears more patent at anterior rhinoscopy, it is still necessary to examine the whole of the nostril before making a selection. Anterior rhinoscopy is best regarded as giving a provisional selection, subject to further examination of the nostril. While studying pathological changes associated with short-term nasal intubation, O'Connell, Stevenson and Stokes 14 used traditional anterior rhinoscopy, presumably with the aid of a nasal speculum, performed before operation by an otolaryngologist to identify pre-existing abnormalities that might cause difficult nasotracheal intubation. One hundred patients were examined and 11 patients were found to have significant deviations by their criteria. They did not report impactions or spurs. There appears to be a discrepancy between their findings (incidence of 11 % septal deviations) and our findings (total incidence 58%). The fact that we used a flexible endoscope to perform a detailed examination of the whole nasal cavity (the videotape record of which could be viewed repeatedly if necessary) rather than performing a simple anterior rhinoscopy probably accounts for the increased detection rate in our study. The primary reason for the anaesthetist to develop fibreoptic skills is to manage difficult intubation. But fibreoptic nasal and oral intubation can also be used in patients who do not present difficulties. Using the fibrescope to facilitate nasal intubation may have advantages over traditional nasal intubation using the Macintosh laryngoscope, provided the anaesthetist is skilled in fibreoptic techniques. Fibreoptic nasotracheal intubation can be performed as quickly or even more quickly than Macintosh nasotracheal intubation 15 (although fibreoptic orotracheal intubation takes significantly longer than Macintosh orotracheal intubation). 16 It simplifies the management of grades 3 and 4 direct laryngoscopies, as defined by Cormack and Lehane. It avoids the possibility of dental damage. It permits a preliminary nasendoscopy which can diagnose or exclude nasal pathology and enable selection of the most patent nostril for intubation, possibly reducing the incidence of nasal trauma. It enables the carina to be identified so that bronchial intubation can be avoided. Anaesthetists who are experienced infibreopticendoscopy should thus consider using fibrescope-guided intubation as their standard technique for securing nasotracheal intubation in suitable maxillofacial patients. References 1 Bainton CR. Complications of managing the airway. In: Benumof JL, ed. 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