A comparison of two silicone-reinforced tracheal tubes with different bevels for use with the intubating laryngeal mask

Seventy consecutive patients were randomly allocated for intubation through the intubating laryngeal mask airway using a straight reinforced silicone tracheal tube with either a conventional or a modified bevel. The conventional bevel was firm, wedge-shaped and with a leading edge at the side. The modified bevel was soft, hemispherical and with a leading edge in the midline. The intubating laryngeal mask position was adjusted until optimal ventilation was obtained and intubation was attempted using the randomised device. If tactile resistance was felt, a predetermined sequence of adjusting manoeuvres were utilised before a subsequent attempt. The first-attempt successful intubation rate with the conventional bevel was 23/37 (62%) and with the modified bevel was 28/33 (85%). The second-attempt successful intubation rate for the conventional bevel was 12/37 (32%) and for the modified bevel was 4/33 (12%). Intubation failed after three attempts for one patient in each group. Fewer overall intubation attempts were required with the modified bevel (p = 0.033). We conclude that intubation success rates through the intubating laryngeal mask with a straight silicone-reinforced tube are higher with a soft, hemispherical bevel with a leading edge in the midline compared with the firm, wedge-shaped bevel with a leading edge at the side.     

Risk factors for epistaxis during nasotracheal intubation

We performed a study to confirm which risk factors are significantly associated with epistaxis during nasotracheal intubation. One hundred patients who underwent nasotracheal intubation were included. Risk factors for epistaxis were analysed using the multiple logistic regression analysis with stepwise variable selection method. Epistaxis was most likely to occur if transit of the tube through the nasal passage was difficult (P=0.0001, odds ratio 625, 95% confidence interval 3.14-14.26). On the other hand, age and gender, obesity, smoking, tube size, repeated attempts of intubation, and intubation performed with the aid of Magillforceps were not significantly related with risk of epistaxis. The presence of nasal anatomical abnormalities also did not correlate significantly with epistaxis. Strategies to ensure smooth transit of the tube through the nasal passageways are essential to reduce the incidence of epistaxis.     

Conventional tracheal tubes for intubation through the intubating laryngeal mask airway

The laryngeal mask airway (LMA)-Fastrach silicone wire-reinforced tracheal tube (FTST) was specially designed for tracheal intubation through the intubating LMA (ILMA). However, conventional tracheal tubes have been successfully used to accomplish tracheal intubation. We designed this study to evaluate the success rate of blind tracheal intubation through the ILMA by using the FTST, the Rusch polyvinyl chloride tube (PVCT), and the Rusch latex armored tube (LAT). One-hundred-fifty healthy adults of ASA physical status I and II who were undergoing elective surgery under general anesthesia were randomly allocated into three groups. FTST (n=50), prewarmed PVCT (n=50), and LAT (n=50) were used for tracheal intubation. Ease of tracheal intubation was assessed by the time taken, the number of attempts, and the number of maneuvers required for success. In addition, numbers of failed intubation attempts and times taken for ILMA removal were also recorded. After surgery, the incidence of trauma, sore throat, and hoarseness was noted. Significantly more frequent success in tracheal intubation was achieved with the PVCT and FTST (96%) compared with the LAT (82%) (P <0.05). Tracheal intubation on the first attempt was similar with the PVCT and FTST (86%) and was significantly more frequent than with the LAT (52%) (P <0.05). Esophageal placement was significantly more frequent with the LAT (29.7%) when compared with the PVCT and FTST (1.8% and 7.4%, respectively) (P <0.05). The authors conclude that a prewarmed PVCT can be used as successfully as the FTST for blind tracheal intubation through the ILMA, whereas the LAT is associated with more frequent failure and esophageal intubation.     

Development of a new system for guidewire‐assisted tracheal intubation: manikin and cadaver evaluation

Guided intubation using a tracheal tube and semi‐rigid introducer is associated with technical difficulties, failure and traumatic complications. We describe the development of a new system of guidewire‐assisted tracheal intubation that may circumvent these problems. A reinforced silicone tracheal tube was modified with a guide channel built inside its wall, and a nitinol non‐kinking guidewire was matched to this channel. Both anterograde and retrograde tracheal intubation were evaluated in a test rig, an airway manikin and then in preserved and fresh cadavers. There was minimal resistance to passage of the guidewire through the guide channel when the modified tube was in an anatomical configuration, in contrast to moderate resistance when an Airway Exchange Catheter was passed through a PVC tracheal tube. Intubation using the new equipment required increased force in the manikin and preserved cadavers, but minimal force in fresh cadavers. Resistance to tracheal tube advancement in preserved cadavers was overcome by withdrawal followed by 90° rotation, but this manoeuvre was not required in fresh cadavers. We suggest that the combination of the modified tracheal tube and matching guidewire may allow easy and reliable single‐step guided tracheal intubation when used in patients.     

The Parker Flex-Tip™ tube for nasotracheal intubation: the influence on nasal mucosal trauma

We tested our hypothesis that use of the Parker Flex-Tip™ tracheal tube could reduce the incidence of nasal mucosal trauma during nasotracheal intubation when compared with a conventional tip tracheal tube. One hundred and two patients, who were scheduled for elective oral surgery in which nasotracheal intubation was indicated to optimise the surgical approach, were recruited into this study. Either a Flex-Tip tracheal tube or a conventional tip tracheal tube was chosen randomly for each nasotracheal intubation. The incidence of epistaxis using the Flex-Tip tracheal tube (6 (11.8%)) was significantly lower than that with the conventional tip tracheal tube (18 (35.3%); p = 0.009). Nasal pain due to intubation, rated on a 100-mm visual analogue scale, was less intense with the Flex-Tip tracheal tube (median, (10th–90th percentile) 19 (12–28) mm compared with the conventional tip tracheal tube (30 (22–35) mm; p < 0.001). The Flex-Tip tracheal tube thus appeared to reduce the incidence of nasal mucosal trauma during nasotracheal intubation and the incidence of post-intubation nasal pain, compared with the conventional tip tracheal tube.     

Flexible lightwand-guided tracheal intubation with the intubating laryngeal mask Fastrach in adults after unpredicted failed laryngoscope-guided tracheal intubation

BACKGROUND: The authors determined the efficacy of using the intubating laryngeal mask airway Fastrach (ILM) as a ventilatory device and aid to flexible lightwand-guided tracheal intubation in patients with unpredicted failed laryngoscope-guided tracheal intubation when managed by experienced anesthetists. METHODS: During a 27-month period, 16 experienced anesthetists agreed to use the ILM as an airway device and airway intubator in patients (aged > 18 yr) with predicted normal airways who were subsequently found to be difficult to intubate (three failed attempts at laryngoscopy). Intubation via the ILM was performed with a flexible lightwand. The number of attempts at ILM placement, the number of adjusting maneuvers, the number of attempts at tracheal intubation via the ILM,and any episodes of hypoxia (oxygen saturation < 90%) were recorded. RESULTS: Forty-four of 11,621 patients (0.4%) met the inclusion criteria. ILM insertion and ventilation was successful at the first attempt in 40 of 44 patients (91%) and at the second attempt in 4 of 44 (9%). Flexible lightwand-guided tracheal intubation via the ILM was successful in 38 of 44 patients (86%) at the first attempt, 3 of 44 (7%) at the second attempt, 2 of 44 (5%) at the third to fifth attempts, and failed in 1 of 44 (2%). The median number of adjusting maneuvers before successful intubation was 1 (range, 0-4). Hypoxia occurred in 5 patients before ILM insertion (range, 52-82%), but none after ILM insertion. No patient developed hypoxia during or after intubation via the ILM. CONCLUSION: The ILM is an effective ventilatory device and aid to flexible lightwand-guided tracheal intubation in adult patients with predicted normal airways in whom laryngoscope-guided tracheal intubation subsequently fails when managed by experienced anesthetists.     

Thermosoftening of the Parker Flex-TipTM Tracheal Tube in Preparation for Nasotracheal Intubation

The Parker Flex-Tip tracheal tube (PFTT, Parker Medical, Highlands Ranch, Colo) has a soft, flexible, curved tip with double Murphy eyes. Previous studies have shown that the PFTT reduces the incidence of epistaxis during nasotracheal intubation and the incidence of postintubation nasal pain, as compared to conventional tracheal tubes. Although thermosoftening is a well-known and effective technique for reducing epistaxis during nasotracheal intubation with conventional tracheal tubes, we occasionally encounter difficulties with advancing the tube through the nasal passage when the PFTT is thermosoftened prior to nasotracheal intubation. Consequently, when using the PFTT for nasotracheal intubation, the procedure of thermosoftening should be avoided.Key Words: Thermosoftening, Tracheal tubesNasal intubation is often required for dental and oral surgical procedures to facilitate complete surgical access to the oral cavity. Various complications resulting from nasotracheal intubation have been reported. However, the most common complication of nasotracheal intubation remains nasal epistaxis.¹ The incidence of nasal epistaxis is high, ranging from 18 to 77%.²The Parker Flex-Tip tracheal tube (PFTT, Parker Medical, Highlands Ranch, Colo) has a soft, flexible, curved tip with double Murphy eyes. Prior et al³ reported that the PFTT may be safer by causing less trauma and bleeding than the standard tube for nasotracheal intubation. A previous report from our hospital has demonstrated that the PFTT reduces the incidence of epistaxis during nasotracheal intubation and the incidence of postintubation nasal pain, as compared to conventional tracheal tubes.⁴ Although thermosoftening is a well-known and effective technique for reducing epistaxis during nasotracheal intubation with conventional tracheal tubes,⁵ we occasionally encounter difficulties in the nasal passage when the PFTT is thermosoftened prior to nasotracheal intubation.During nasotracheal intubation, the distal tip of the endotracheal tube is inserted through the naris into the oropharynx. At this point, the endotracheal tube can impinge on the posterior wall of the nasopharynx, where the nasal passage turns acutely.⁶ The soft distal tip of the PFTT becomes softer with thermosoftening,⁷ and may easily collapse upon impact. Xue et al⁸ described how the PFTT may collapse upon impact, even if it has not been thermosoftened. We suspect that the tip of a thermosoftened PFTT does not slide smoothly downward when pressed directly against the posterior wall of the nasopharynx, and can result in decreased navigability through the nasal passage.Since thermosoftening of the PFTT may impair smooth navigability through the nasal passage, the PFTT should be used for nasotracheal intubation without prior thermosoftening of the tip of the tube.     

The GlideScope for videolaryngoscopy-assisted nasotracheal-to-orotracheal tube exchange in the intensive care unit in a patient with a known difficult airway

A 77 year old, nasally intubated man with a history of repeated episodes of airway obstruction requiring intubation due to recurrent laryngitis and a hypopharyngeal mass, needed nasotracheal-to-orotracheal tube exchange. The GlideScope videolaryngoscope was inserted, achieving a full view of the glottic inlet with the nasotracheal tube in situ. An endotracheal tube (ETT) loaded on a GlideRite Rigid Stylet was advanced through the oropharynx into view. Advancement of this ETT to the glottic opening was tested and achieved. With both tracheal tubes in view, the nasotracheal tube cuff was deflated and withdrawn from the glottic opening. While maintaining videoscopic visualization, the orotracheal tube was advanced through the vocal cords into the trachea. The benefits of this technique versus existing alternatives are discussed.     

A comparison of tracheal tube tip designs on the passage of an endotracheal tube during oral fiberoptic intubation

BACKGROUND: The design of an endotracheal tube has been shown to influence the passage of the tube through the glottis during fiberoptic intubation. Difficulty in passing the endotracheal tube can occur if the aryepiglottic folds obstruct the passage of the bevel. The relevant aspects of endotracheal tube design include the shape of the bevel, the material used by the manufacturer, and the ability of the tube to conform to the shape of the fiberscope. The aim of the current study was to compare the ease of passage through the glottis of two different tubes. One tube was a wire reinforced polyvinyl chloride tube with a standard bevel and the other was a newly designed tube with a bevel of different shape and made of silicone rubber. The new design is for use with the a commerical intubating laryngeal mask. METHODS: The authors studied a population of 30 patients who received a standard anesthetic. In all cases, oral fiberoptic intubation was attempted. Anesthetic was administered to each patient using both tubes, and before the study the order of the tubes was randomized. The difficulty in passing the tube was assessed by a blinded observer and graded using a three-point scale (grade 1: no difficulty passing the tube; grade 2: obstruction to passing the tube relieved by withdrawal and a 90 degrees anticlockwise rotation; grade 3: obstruction necessitating more than one manipulation or external laryngeal manipulation). RESULTS: In 27 patients, no difficulty was shown by use of the silicone-tipped tube. In only three patients was there difficulty that necessitated a 90 degrees anticlockwise twist. With the wire-reinforced tube, no difficulty was experienced on 14 occasions. Grade 1 difficulty was experienced eight times and difficulty necessitating more than one maneuver, head movement, or external laryngeal manipulation was seen on eight occasions. Statistical significance was achieved at P = 0.0002 (Wilcoxon signed rank test). CONCLUSIONS: The authors conclude that the use of the silicone-tipped tube with the new bevel design may provide an advantage in the clinical situation of fiberoptic intubation.     

The LMA Fastrach™ facilitates fibreoptic intubation in oral cancer patients

PURPOSE: To compare ease of endotracheal intubation with the Intubating Laryngeal Mask Airway (ILMA) tracheal tube (TT; for LMA-Fastrach) and regular PVC TT (Portex) for nasotracheal fibreoptic intubation in oral cancer patients with a difficult airway. METHODS: 40 patients of physical status ASA I-II with a history of previous oral cancer surgery and/or postoperative radiotherapy scheduled for oral cancer surgery were randomly allocated by sealed envelopes to undergo tracheal intubation with either the ILMA TT or a standard TT. Ease of nasal passage of the TT and ease of tracheal intubation over the fibrescope was assessed. Peak airway pressures were assessed intraoperatively and postoperatively for 12 hr. RESULTS: The use of the ILMA TT increased the ease of nasotracheal intubation by increasing the percentage of successful tube placements at the first attempt (80%) in comparison with standard TT (35%); (P < 0.05). Peak airway pressures were found to remain low with the ILMA TT. None of the patients experienced any airway related complications. CONCLUSIONS: Use of a soft, flexible, nonkinking ILMA TT with a tapered tip design facilitates passage into the trachea over a fibreoptic bronchoscope and allows maintenance of lower airway pressures. The ILMA TT may be a useful adjunct for management of the difficult airway in oral cancer surgery.     

Which nostril should be used for nasotracheal intubation: the right or left? A randomized clinical trial

Study ObjectiveTo determine which nostril is more suitable for nasotracheal intubation in patients with normal patency of both nostrils.DesignProspective, randomized clinical trial.SettingOperating room of a university medical center.Patients191 ASA physical status 1 and 2 patients scheduled for elective oral surgery requiring general anesthesia with nasotracheal intubation.InterventionsPatients were randomized to two groups to undergo nasotracheal intubation through the right nostril (Group R; n = 96) or the left nostril (n = 95). Standard traditional nasotracheal intubation was performed using the Macintosh laryngoscope. Tube rotation was attempted for alignment toward the glottis, and Magill forceps were then used to assist intubation, as necessary.MeasurementsEpistaxis was inspected in the pharynx after the tube tip was passed through the nasal cavity and 15 minutes after nasotracheal intubation was completed. Intubation time was the interval between when the anesthesiologist opened the patient’s mouth with the cross finger maneuver and when the tube was connected to the anesthetic circuit after nasotracheal completion.Main ResultsThe frequency of epistaxis was significantly lower in Group R than Group L (P = 0.0006). Although there was no significant difference in nasal passage time between two groups, the intubation time in Group R (24.5 ± 9.4 sec) was shorter than in Group L (30.5 ± 15.6 sec; P = 0.0015).ConclusionNasal intubation via the right nostril is more safely performed than with the left nostril. Because of less epistaxis and faster intubation.     

The effects of tracheal tube tip design and tube thickness on laryngeal pass ability during oral tube exchange with an introducer

We compared the ease of passage through the glottis of two different tubes and two different sizes of tracheal tube exchanger (TE) during introducer-guided tracheal intubation. One tube was a polyvinyl chloride tube with a standard bevel, and the other was a newly designed tube with a hemispherical bevel. The outer diameters (OD) of the two TEs were 2.5 and 5.0 mm. After the standard induction of anesthesia, followed by vecuronium-induced paralysis, a TE was inserted into the trachea with a direct laryngoscope. By using the introducer as a guide, the tracheal tube was inserted into the trachea. The difficulty in passing the tube was assessed by a blinded observer and graded with a four-point scale. The newly designed tube was inserted more smoothly than was the conventional tube when the 2.5-mm-OD TE was used (P < 0.01). In situations such as those occurring after one-lung anesthesia, when use of a thicker TE is not applicable, this newly designed taper-tipped tube may be considered as an adjunct to oral tracheal tube exchange, using a thinner (smaller-OD) TE as the guide for tracheal intubation. IMPLICATIONS: In situations such as after one-lung anesthesia, when use of a thicker tube exchanger (TE) is not applicable, a newly designed taper-tipped tube with the leading edge in the midline may be considered as an adjunct to an oral tracheal tube exchange, using a thinner TE as the guide for tracheal intubation.     

Use of gum elastic bougie for tracheal intubation: comparison of different tracheal tubes

BACKGROUND: Gum elastic bougie (GEB) is one of the most useful devices for patients whose tracheas are difficult to intubate during anesthetic induction. But no previous study has evaluated the effects of the types of the tracheal tube. We hypothesized that wire-reinforced tracheal tubes were superior to standard tracheal tubes in the success rate of tracheal intubation when using GEB. We compared these two different types of tracheal tubes in using GEB. METHODS: Forty patients were subjected and randomly allocated into two groups; patients intubated with standard tracheal tubes (Group , n = 20) and those with wire-reinforced tracheal tubes (Group S, n = 20). Measured variables were intubation time defined as elapsed time from mouth opening to removal of GEB from tracheal tube, heart rate (HR), and systolic blood pressure(SBP). We also compared trial times of intubation and pharyngeal or laryngeal bleeding as a minor side effect. RESULTS: Trachea was successfully intubated in the frist attempt in 37 patients (92.5%), and the rest of the patients were all intubated at second trial. Intubation times of Group P and Group S were 41.5 +/- 13.9s and 41.3 +/- 11.1s, respectively. There were no significant differences in HR and SBP between the groups. CONCLUSIONS: The type of tracheal tube would not affect the success rate and time of intubation when using gum elastic bougie.     

Nasotracheal intubation under curve-tipped suction catheter guidance reduces epistaxis

BACKGROUND: Nasotracheal intubation (NTI) has greater potential for trauma of nasopharyngeal mucosa than orotracheal intubation. The present study investigated the success rate of NTI and frequency of nasal bleeding using a curve-tipped suction catheter (CTSC) to guide nasotracheal tube advancement. METHODS: Subjects comprised 131 adult patients who under-went NTI. Subjects were randomly divided into two groups: a) NTI under CTSC guidance (G[+] group). The CTSC (14 Fr) was first inserted through the tracheal tube, with the tip of the CTSC emerging from the distal end of the tube. The curved tip was directed ventrally. Both tracheal tube and CTSC were advanced together through the nasopharynx; b) NTI without CTSC guidance (G[-] group). The tracheal tube was advanced into the nasal cavity and passed into the pharynx without CTSC guidance. The time required to pass the endotracheal tube through the nasal cavity (nasal passage time), success rate of nasal passage with nasotracheal tube, and the incidence and severity of nasal bleeding were compared. RESULTS: Success rate for nasal passage was 100% in the G(+) group (62/62) and 82.6% in the G(-) group (57/69; P = 0.0006). Frequency of nasal bleeding was significantly lower in the G(+) group (21/62, 33.9%) than in the G(-) group (37/69, 53.6%; P = 0.023). Severity of nasal bleeding was also significantly lower in the G(+) group than in the G(-) group (P = 0.030). CONCLUSIONS: Nasotracheal intubation under CTSC guidance increases the success rate of airway instrumentation, and also reduces the incidence and severity of epistaxis.     

Guided insertion of the ProSeal laryngeal mask airway is superior to conventional tracheal intubation by first-month anesthesia residents after brief manikin-only training

In the following pilot study, we compared conventional laryngoscope-guided tracheal intubation (tracheal intubation) and laryngoscope-guided, gum elastic bougie-guided ProSeal laryngeal mask airway insertion (guided ProSeal) for airway management by first-month anesthesia residents after brief manikin-only training. Five first-month residents with no practical experience of airway management were observed performing these techniques in 200 ASA I-II anesthetized, paralyzed adults. Each resident managed 40 patients, 20 in each group, in random order. The number of insertion attempts, effective airway time, ventilatory capability during pressure-controlled ventilation set at 15 cm H2O, airway trauma, and skill acquisition were studied. Data were collected by unblinded observers. Insertion was more frequently successful (100% versus 65%) and effective airway time was shorter (41 +/- 24 s versus 89 +/- 62 s) in the guided ProSeal group (both P < 0.0001). Expired tidal volume was larger (730 +/- 170 mL versus 560 +/- 140 mL) and end-tidal CO(2) lower (33 +/- 4 mm Hg versus 37 +/- 5 mm Hg) in the guided ProSeal group during pressure controlled ventilation (both P < 0.0001). Blood staining was more frequent on the laryngoscope (24% versus 2%; P < 0.0001) in the tracheal intubation group. There was evidence for skill acquisition in both groups. We conclude that laryngoscope-guided, gum elastic bougie-guided insertion of the ProSeal laryngeal mask airway is superior to conventional laryngoscope-guided tracheal intubation for airway management in terms of insertion success, expired tidal volume, and airway trauma by first-month anesthesia residents after brief manikin-only training. The guided ProSeal technique has potential for cardiopulmonary resuscitation by novices when conventional intubation fails.     

A Comparison of Tracheal Tube Tip Designs on the Passage of an Endotracheal Tube during Oral Fiberoptic Intubation

Background: The design of an endotracheal tube has been shown to influence the passage of the tube through the glottis during fiberoptic intubation. Difficulty in passing the endotracheal tube can occur if the aryepiglottic folds obstruct the passage of the bevel. The relevant aspects of endotracheal tube design include the shape of the bevel, the material used by the manufacturer, and the ability of the tube to conform to the shape of the fiberscope. The aim of the current study was to compare the ease of passage through the glottis of two different tubes. One tube was a wire reinforced polyvinyl chloride tube with a standard bevel and the other was a newly designed tube with a bevel of different shape and made of silicone rubber. The new design is for use with the a commerical intubating laryngeal mask.

Methods: The authors studied a population of 30 patients who received a standard anesthetic. In all cases, oral fiberoptic intubation was attempted. Anesthetic was administered to each patient using both tubes, and before the study the order of the tubes was randomized. The difficulty in passing the tube was assessed by a blinded observer and graded using a three-point scale (grade 1: no difficulty passing the tube; grade 2: obstruction to passing the tube relieved by withdrawal and a 90[degrees] anticlockwise rotation; grade 3: obstruction necessitating more than one manipulation or external laryngeal manipulation).

Results: In 27 patients, no difficulty was shown by use of the silicone-tipped tube. In only three patients was there difficulty that necessitated a 90[degrees] anticlockwise twist. With the wire-reinforced tube, no difficulty was experienced on 14 occasions. Grade 1 difficulty was experienced eight times and difficulty necessitating more than one maneuver, head movement, or external laryngeal manipulation was seen on eight occasions. Statistical significance was achieved at P = 0.0002 (Wilcoxon signed rank test).     

Reliability of assessment of nasal flow rate for nostril selection during nasotracheal intubation

Study ObjectiveTo evaluate the reliability of assessments of nasal flow rate for improved nostril selection for nasotracheal intubation.DesignProspective, randomized, double-blinded study.SettingOperating room of a university-affiliated hospital.Patients118 ASA physical status 1 and 2 patients, aged 18-65 years, scheduled for elective maxillofacial and oral surgery requiring nasotracheal intubation.InterventionsPatients were randomized to the left or right nostril groups. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV₁) through the mouth and each nostril were measured before anesthesia induction.MeasurementsThe relationship between the rate of airflow through the selected nostril and frequency of epistaxis and navigability of the nasotracheal tube were evaluated.Main ResultsThere were no significant differences in the frequency of epistaxis and degree of navigability of the tracheal tube between the left and right nostril groups. In both nostril groups, patients who suffered epistaxis showed significantly less FEV₁ and FEV₁/FVC values than did patients without epistaxis (P < 0.05). In addition, in both groups patients who passed the tube easily showed significantly higher FEV₁ and FEV₁/FVC values than did patients who passed the tube with resistance or failed tube passage (P < 0.05).ConclusionMeasurement of nasal flow rate is a useful clinical method for choosing a nostril for nasotracheal intubation.     

Nasotracheal tube placement over the fibreoptic laryngoscope

We have assessed the effectiveness of three tracheal tube rotational movements in assisting nasotracheal tube placement over the fibreoptic laryngoscope. Ninety ASA grade 1 or 2 oral surgery patients undergoing fibreoptic nasotracheal intubation under general anaesthesia were studied. After the fibrescope had been positioned in the trachea, patients were randomly allocated to one of three groups. In group 1, no rotation was used and the tube was advanced towards the trachea in the neutral position. In group 2, the tube was rotated by 90° anticlockwise. In group 3, the tube was rotated by 180° anticlockwise, then rotated back to 90° anticlockwise (overcorrected rotation). If resistance to the advance was encountered, up to two more attempts were allowed, after further rotational manoeuvres had been made, in accordance with a standard, graduated sequence. There were significantly more successful tube placements at the first attempt in groups 2 and 3 (93% and 100% respectively) than in group I (63%). It is therefore recommended that 90° anticlockwise or overcorrected 90° anticlockwise tube rotation is used to facilitate nasotracheal tube placement during fibreoptic intubation.     

Determination of the site of tracheal tube impingement during nasotracheal fibreoptic intubation

This study examines the incidence and site of tracheal tube impingement during nasotracheal fibreoptic intubation, and the efficacy of anticlockwise tube rotation to overcome the problem. Forty-three patients underwent fibreoptic-assisted nasotracheal intubation using a preformed nasal tube, and a second fibrescope was used to observe any obstruction to passage of the tracheal tube. Impingement occurred in 10 cases, with the most common site being the right arytenoid cartilage. Rotation resulted in successful intubation in all 10 cases, but proximal rotation did not always result in an equal degree of rotation at the tube tip. We conclude that the site of impingement for nasotracheal intubation with preformed nasal tubes is located at the posterior structures of the laryngeal inlet and that anticlockwise rotation is a simple and effective solution.     

"Tube scratching" in the trachea on nasotracheal intubation: comparison of Macintosh and McCoy laryngoscopes

BACKGROUND: "Tube scratching" in the trachea, the intratracheal resistance of a tube, on nasotracheal intubation was evaluated using the Macintosh and the McCoy laryngoscope blade. METHODS: Fifty young patients requiring nasotracheal intubation were studied. Following induction of anesthesia, X-ray was taken before and during the use of two types of laryngoscopes. For analysis of the configuration of the upper airway, we drew three straight lines [axis of pharynx (P), larynx (L) and trachea (T)] on each film. "Tube scratching" was evaluated and graded to four by a supporting anesthesiologists. RESULTS: "Tube scratching" in the trachea was observed in 14/25 patients with McCoy laryngoscope and 4/25 patients with Macintosh laryngoscope (P < 0.05). Intubation with McCoy laryngoscope decreased more the angles formed by P and L, and L and P those that with Macintosh laryngoscope (P < 0.01). These data indicate that the lines of P, L and T tend not to align with McCoy laryngoscope, preventing the tracheal tube to be passed smoothly. CONCLUSION: An excessive lifting of the epiglottis, often observed in using McCoy laryngoscope, causes "Tube scratching" in the trachea on nasotracheal intubation.