BJA Advance Access originally published online on June 21, 2007
British Journal of Anaesthesia 2007 99(2):292-296; doi:10.1093/bja/aem127
Comparison of intubating laryngeal mask airway and Bullard laryngoscope for oro-tracheal intubation in adult patients with simulated limitation of cervical movements
Department of Anaesthesiology, Kasturba Medical College, Manipal, Karnataka, India
* Corresponding author: Department of Anaesthesiology, Kasturba Medical College, Manipal, Karnataka, India E-mail: anitharshenoy{at}yahoo.co.in
Accepted for publication April 5, 2007.
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Abstract |
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Background: Intubation of a patient with limited cervical spine movement or in whom movement of the cervical spine is not desirable is always a challenge even to the most experienced anaesthesiologist. The intubating laryngeal mask airway (ILMA) and the Bullard laryngoscope (BL) are two instruments recommended for endotracheal intubation of such patients. We compared their utility and safety in patients with simulated cervical spine immobility using manual inline stabilization (MILS).
Methods: Sixty-two patients, ASA I or II, between 18 and 65 yr, were enrolled in this prospective and randomized study. They were randomly allocated to one of the two groups: Group BL (Bullard laryngoscope) and Group IL (Intubating Laryngeal Mask Airway). The patients were intubated orally using either equipment after induction of general anaesthesia.
Results: The success rate for intubation in the first or second attempt was higher in Group BL [90.32% (28/31)] than in Group IL [74.2% (23/31)] but was not statistically significant. The number of attempts taken for intubation and the total time to intubate were similar between the groups. Trauma as evidenced by blood on endotracheal tube or sore throat was similar in both groups.
Conclusions: Both the BL and the ILMA are useful equipment in intubating patients with limitation of cervical movements. Although not statistically significant, the BL may provide a higher success rate of intubation when compared with the ILMA.
Keywords: equipment, airway; equipment, laryngoscopes; position, neck
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Introduction |
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Endotracheal intubation of a patient with limited cervical spine movement or in whom movement of the cervical spine is not desirable is always a challenge even to the most experienced anaesthesiologist. In cases of cervical spine immobility/instability, direct laryngoscopy is still the fastest and the easiest method of securing the airway, but it requires flexion of the cervical spine and atlanto-occipital extension for alignment of the oral, pharyngeal and laryngeal axes to create a direct line of vision from the mouth to the vocal cords which could be harmful. Under such difficult circumstances, the application of a safe and rapid technique, with which to secure the airway, is essential.
Awake fibreoptic bronchoscopy is considered safe and is a first choice for these patients. The Bullard laryngoscope (BL) and the intubating laryngeal mask airway (ILMA, FastrachTM), a modified conventional laryngeal mask airway, are alternatives that may prove useful when the fibreoptic bronchoscope is not available. We conducted this study comparing the success rate of intubation and the incidence of complications using these two techniques.
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Methods |
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Sixty-two patients, ASA I or II, between 18 and 65 yr, weighing 40–80 kg, 150–180 cm tall, and undergoing elective surgery under general anaesthesia requiring oro-tracheal intubation were included in this prospective, randomized study. Approval of the Local Ethics Committee was obtained. Informed consent was obtained from all the patients for the procedure. Patients requiring awake tracheal intubation/rapid sequence induction of anaesthesia or presenting with anticipated difficult airway were excluded from the study. Patients undergoing neck surgeries and those requiring the insertion of throat pack or a nasogastric tube were also excluded.
An anaesthesiologist with 2 or more years of experience in airway management (Observer 1) assessed all patients on the day before surgery and ensured that the inclusion criteria were met and none of the exclusion criteria was present. He assessed the mouth opening (MO) in cm, thyromental distance in cm, temporomandibular joint movement, the modified Mallampatti class (MMC), and range of neck movements. All patients were kept nil per oral for both solids and liquids for 6 h before surgery. Premedication consisted of Tab Lorazepam 1 mg (<50 kg) or 2 mg (>50 kg) orally the night before and 2 h before surgery.
Patients were randomly assigned using a random number generator to be intubated using either a Bullard Laryngoscope (Group BL) or an ILMA (Group IL). All intubations were done by a staff anaesthesiologist (AS) trained in difficult airway management techniques (Observer 2).
In the operating room, the patients were monitored using ECG, non-invasive blood pressure (NIBP), and a pulse oximeter (SpO2). I.V. access was secured and inj. glycopyrrolate 0.2 mg was given i.v. General anaesthesia was induced with thiopentone (5 mg kg–1) i.v. Post-induction monitors included capnograph (E'CO2) and a peripheral nerve stimulator. Effective mask ventilation was confirmed and muscle relaxation was achieved using vecuronium bromide 0.1 mg kg–1 i.v. Anaesthesia was maintained with halothane [1% in oxygen (6–8 litre min–1)], intermittent positive pressure ventilation using a semi-closed circle absorber.
The pillow under the head was removed. Three minutes after giving neuromuscular blocking agent, manual inline stabilization (MILS) was given by the anaesthesiologist in-charge of the case (Observer 3). Direct laryngoscopy was performed by Observer 1 using a Macintosh blade size 4 for males and size 3 for females to grade the laryngoscopic view (Cormack and Lehane). No laryngeal manipulation was done during grading.
Once the responses to train-of-four stimulation (12 s repeat TOF) were absent, endotracheal intubation was attempted with the BL or the ILMA depending on the group to which the patient was assigned. Endotracheal tube (ETT) [polyvinyl chloride (PVC)] of size 7 mm ID for females and size 8 mm ID for males was used in all patients of either group. Tracheal intubation was performed by Observer 2 using either ILMA or BL, with continued MILS. Tracheal intubation was considered successful with a device only if the patient was intubated in one or two attempts and when that device was first assigned to the patient.
Group IL
ILMA size 3 for females and size 4 for males was used. The cuff of ILMA was partially inflated, and the posterior surface of the mask was lubricated with lidocaine jelly to facilitate insertion. The mouth was opened as wide as possible and a jaw thrust was given with the left hand. The ILMA was gradually introduced into position with a one-handed rotational movement using the steel handle. The cuff of the ILMA was inflated with air (to a total of 20 ml for size 3 and 30 ml for size 4 ILMA), and ability to ventilate was confirmed.
Holding the steel handle with the left hand, the lubricated ETT was passed into ILMA, with the concavity facing cephalad and further into the trachea. Tracheal tube position was confirmed using a capnograph, bilaterally equal chest movements, and air entry.
After successful intubation through ILMA, the distal tip of a 6 mm ID ETT was inserted into the proximal end of the ETT in trachea (with the standard 15 mm connectors removed). The 6 mm ID tube served as the stabilizing rod for the first ETT as the ILMA was removed. The position of the first ETT was then reconfirmed. If the first attempt was unsuccessful, the algorithm adopted by Brain and colleagues1 was followed.
If the second attempt was unsuccessful, intubation with BL was attempted once. If the intubation with BL was also unsuccessful, endotracheal intubation was done using a Macintosh laryngoscope after optimization of position for intubation without MILS. Patients were ventilated with halothane in oxygen in between the attempts to intubate.
Group BL
A fibreoptic light source was attached to BL. The ETT was preloaded onto the lubricated, dedicated stylet of the BL. The angle of the tip of the dedicated stylet was changed to 15° from 30° at the beginning of the study. The concave surface of the laryngoscope blade was also lubricated. The light of BL on the blade was touched with ‘savlon’ to prevent ‘fogging’.
The BL and stylet (with ETT) were held together firmly at the junction of eyepiece and the laryngoscope blade such that any slipping of the stylet and trauma to oro-pharyngeal structures during introduction was prevented. The stylet and the ETT were positioned in the right posterior aspect of the blade. The BL was introduced as a single unit into the mouth in the midline. It was initially introduced with its longitudinal length horizontal (parallel to the ground) and was gradually slid along the tongue to bring it to vertical position.
Difficulty encountered in passing the tube even when the larynx was seen was most likely due to the BL being too close to the larynx and the ETT hitching against the arytenoids. In such cases, the BL was withdrawn a little and intubation attempted. If the second attempt with BL was unsuccessful, intubation was attempted with ILMA (size 3 for females and size 4 for males) once. If intubation with ILMA was also unsuccessful, the position of the head and neck was optimized and endotracheal intubation was achieved using a Macintosh laryngoscope. Patients were ventilated with halothane 1% in oxygen in between the attempts.
Observer 1 recorded the time to intubate in seconds. In both the groups, each attempt at intubation was timed. The time from beginning of insertion of the device to the confirmation of intubation by capnography was recorded as time for intubation. If intubation was unsuccessful, each of the further attempts excluding the period of interposed ventilation was timed separately. The total time of intubation(s) was taken as the sum of the time taken at each attempt at intubation until intubation was achieved.
Observer 3 monitored NIBP, heart rate, and SpO2 before preoxygenation, every minute after induction until 5 min post-intubation. These parameters were recorded automatically by the monitor.
Any trauma during intubation was assessed by presence or absence of blood on the ETT after extubation. In addition, the patients were questioned about complaints of sore throat and were graded (Table 1).
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The sample size was determined from a previous pilot study to be 31 in each group, allowing an alpha-error of 0.05 and a beta-error of 0.2 (power of 80%) to detect a difference of 15% in the success rate of intubation. Parametric data (age, weight, height, and total time to intubate) were compared using Student's t-test. Discrete variables (sex, success rate, and side-effects) were compared using
2 test or the Fisher's exact test. A P-value of < 0.05 was considered as statistically significant. |
Results |
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There were no differences in age, weight, height, and gender characteristics of patients between the two groups (Table 2). Preoperative airway characteristics and the laryngoscopic grade after removal of the pillow under the head and subsequent application of MILS showed no difference between the two groups (Table 3).
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Twenty-eight out of the total 31 patients in Group BL were intubated with the BL in one or two attempts (90.32%). Twenty-four of these were intubated in the first attempt (85.7%). Of the 31 patients in Group IL, 23 were intubated in one or two attempts (74.19%). Only 15 out of the total 23 patients were intubated successfully in the first attempt (65.2%) (Table 4). The number of attempts taken for intubation or the total time to intubate in seconds were not different between the two groups (Table 4).
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In Group BL, three patients could not be intubated with the BL in two attempts. Subsequently, intubation was successful with ILMA in one of them but failed in two. In Group IL, endotracheal intubation failed with the ILMA in eight patients. One of them was not assigned to BL due to an undue hypertensive response to previous intubation attempts. In the seven patients where intubation was attempted with BL, four could be intubated successfully. Among the three patients in whom intubation with the BL failed, the larynx was well seen in one patient, but the tube was passed into the oesophagus. In another, the view was masked because of fogging of the lens. In both of these patients, intubation with the BL may have been successful if another attempt was given. In the third patient, the larynx was not visualized, but the patient had frequent ventricular premature contractions and it was decided not to pursue laryngoscopy with the BL. Thus, although the difference between the groups did not reach statistical significance, the BL seemed much more useful clinically.
Trauma during the use of either instrument was checked by the presence of blood on the ETT and further checked by the presence of sore throat after operation (Table 5). The incidence of trauma was not different with the use of either instrument.
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The incidence of trauma was higher in patients who required a third intubation attempt. Of the three patients in Group BL, two had blood on the ETT. In Group IL, all seven patients had blood on the ETT. The groups were not compared, as the numbers were small. Any trauma could not be attributed to either instrument in such a situation. Haemodynamic changes were monitored during the study and were not different between the groups.
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Discussion |
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Endotracheal intubation has to be done with utmost care in patients with cervical spine fractures or other cervical pathology requiring the use of cervical collar for stabilization. Care should be taken to ensure that no trauma occurs due to excessive movements of the spine either flexion, extension, or rotation. Application of a Philadelphia collar is very effective in preventing movement of the cervical spine while intubating these patients. However, this collar limits the MO and makes laryngoscopy and intubation even more difficult. An alternative is to apply MILS by an assistant such that no movement at cervical spine is allowed during laryngoscopy and intubation.
Direct laryngoscopy and intubation is the fastest method of securing the airway2 but may be harmful.3 Other methods that have been described are the fibreoptic bronchoscope, laryngeal mask airway, ILMA, and the BL. The fibreoptic bronchoscope is the method of choice in these patients.4 However, it is not freely available and alternative methods become necessary. A study by Onizuka and colleagues compared endotracheal intubation with the ILMA and BL showed that the BL was faster and more successful than the ILMA. However, the authors had used a fibreoptic laryngoscope to intubate through ILMA.5 We wanted to study the success rate of intubation through ILMA blindly rather than using a fibreoptic bronchoscope. An ILMA would most likely be used when the fibreoptic bronchoscope or expertise for its use is not available.
The success rate of blind intubation through the ILMA varies from 85% to 100%6–13 in the literature. Most have used a silicone ETT for intubation. Our success rate was only 74.19%. This may have been due to the fact that we used PVC tubes for intubation through the ILMA. The PVC tubes are economical, disposable, and readily available in comparison with the straight silicone ETT which are expensive, have to be autoclaved, and are not freely available. In addition, these were the tubes we used with the BL. Various studies with ILMA have involved the use of PVC tubes for intubation.7 8 14 15
Lu and colleagues15 compared the performance of the ILMA in assisting blind tracheal intubation, with conventional tubes of different curvatures, and the frequency of possible associated complications. They conducted a single blinded trial to receive blind tracheal intubation via the ILMA, with a conventional tracheal tube curved with Normal (Normal group) or Reversed (Reversed group) direction. The overall success rate of intubation was higher in the Reverse group (89.6%) than in the Normal group (85%). The incidence of sore throat was higher in the Normal group (19.2%) than in the Reverse group (9.2%).
We limited the attempts at intubation with the first equipment to two and a single attempt was allowed for the second equipment to avoid undue trauma to the pharyngeal and laryngeal structures. The restriction on attempts may have affected the success rate with either equipment, especially the second.
With the BL, once visualization of glottis was achieved, care had to be taken not to be too close to the glottis. In addition, the tip of the laryngoscope needed to be rotated a little to the left side of the glottic inlet so that the tube that is advanced does not hitch against the right arytenoids cartilage. The requirement to gently rotate the tip of the BL remained even after the angle of the stylet had been changed to 15°.
Direct laryngoscopy usually takes a much shorter time but only when the view is adequate. The BL and the ILMA are used in situations where the use of direct laryngoscope is either undesirable or inadequate. Of the total 62 patients enrolled in the study, 30 patients had a Cormack and Lehane laryngoscopic Grade III or IV with MILS. Twenty-six patients (86%) were intubated with either device. Twenty-two (73%) were intubated with the primary device assigned. Another four (13%) were intubated with the alternate device (Table 6).
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Intubation with ILMA failed in one patient in Group IL who had a Grade III view but could not be assigned to intubation with BL as there was a clinically significant hypertensive response. During this study, no manipulation of the larynx was done while grading the view, and we do not know whether the view may have improved with backward, upward, or rightward pressure, but it is possible that these patients may have been difficult to intubate with a direct laryngoscope.
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Conclusions |
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TopAbstractIntroductionMethodsResultsDiscussionConclusionsReferences |
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Both the BL and the ILMA are useful equipment in intubating patients with simulated limitation of cervical movements using manual inline stabilization. The BL may provide higher success rate of intubation when compared with the ILMA. However, ILMA is easier to use as most anaesthesiologists are familiar with the insertion of a standard LMA and insertion of the ETT may be accomplished blindly through the LMA. The ILMA has the added advantage of ability to ventilate a patient in the event of inability to intubate.
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References |
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1 Brain AIJ, Verghese C, Addy EV, Kapila A, Brimacombe J. The intubating laryngeal mask. II: a preliminary clinical report of a new means of intubating the trachea. Br J Anaesth (1997) 79:704–9.
2 Smith CE, Pinchak AB, Sidhu TS, Radesic BP, Pinchak AC, Hagen JF. Evaluation of tracheal intubation difficulty in patients with cervical spine immobilization: fiberoptic (WuScope) versus conventional laryngoscopy. Anesthesiology (1999) 91:1253–9.[CrossRef][Web of Science][Medline]
3 Fitzgerald RD, Krafft P, Skrbenski G, et al. Excursions of the cervical spine during tracheal intubation: blind oral intubation compared with direct laryngoscope. Anaesthesia (1994) 49:111–5.[CrossRef][Web of Science][Medline]
4 Rosenblatt WH, Wagner PJ, Ovassapian A, et al. Practice patterns in managing the difficult airway by anaesthesiologists in the United States. Anesth Analg (1998) 87:153–7.
5 Onizuka S, Kawano T, Takasaki M. A comparison of Bullard laryngoscope and intubating laryngeal mask using fibreoptic guidance for tracheal intubation. Masui (2000) 49:736–9.[Medline]
6 Asai T, Morris S. The laryngeal mask airway—its features, effects and role. Can J Anesth (1994) 41:930–60.[Web of Science][Medline]
7 Baskett PJ, Parr MJ, Nolan JP. The intubating laryngeal mask. Results of a multicentre trial with experience of 500 cases. Anaesthesia (1998) 53:1174–9.[CrossRef][Web of Science][Medline]
8 Branthwaite MA. An unexpected complication of the intubating laryngeal mask. Anaesthesia (1999) 54:166–7.[CrossRef][Web of Science][Medline]
9 Kapila A, Addy EV, Vrghese C, Brain AI. The intubating laryngeal mask airway: an initial assessment of performance. Br J Anaesth (1997) 79:710–3.
10 Brain AJ, Verghese C, Addy EV, Kapila A. The intubating laryngeal mask. 1: development of a new device for intubation of the trachea. Br J Anaesth (1997) 79:699–703.
11 Ferson DZ, Brimacombe J, Brain AIJ, Verghese C. The intubating laryngeal mask airway. Int Anesth Clinics (1998) 36:183–209.
12 Rosenblatt WH, Murphy M. The intubating laryngeal mask: use of a new ventilating intubating device in the emergency department. Ann Emerg Med (1999) 33:234–8.[CrossRef][Web of Science][Medline]
13 Moller F, Andres AH, Langenstein H. Intubating laryngeal mask airway (ILMA) seems to be an ideal device for blind intubation in case of immobile spine. Br J Anaesth (2000) 85:493–5.[Medline]
14 Joo HS, Rose DK. The intubating laryngeal mask airway with and without fiberoptic guidance. Anesthesiology (1999) 88:662–6.
15 Lu PP, Yang CH, Ho ACY, Shyr MH. The intubating LMA: a comparison of insertion techniques with conventional tracheal tubes. Can J Anaesth (2000) 47:849–53.[Web of Science][Medline]
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