AJA Asian Journal of Anesthesiology

Advancing, Capability, Improving lives

Original Articles
Volume 52, Issue 3, Pages 110-113
Bikramjit Das 1 , Subhro Mitra 1 , Arijit Samanta 2 , Rajiv Kumar Samal 3
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Abstract

Background

Combined introducer tool and stylet technique of ProSeal laryngeal mask airway (PLMA) insertion was compared with the conventional digital manipulation and introducer tool technique in children with a rigid neck collar.

Methods

This was a randomized, single blinded, prospective study. Ninety ASA Grade I–II children weighing 10–20 kg were randomly allocated for PLMA insertion using the digital, introducer tool (IT) or combined IT and stylet techniques. Each group contained 30 patients. Difficult laryngoscopy was simulated using a rigid neck collar. The laryngoscopic view was graded prior to PLMA insertion. The digital and IT techniques were performed according to the manufacturer's instructions. The combined technique involved attaching the IT to the PLMA and inserting a flexible stylet through the drain tube.

Results

The median Cormack and Lehane grade was 2 in all three groups. Insertion was more frequently successful with the combined technique at the first attempt (combined 100%, digital 65.38%, IT 66.67%; p < 0.05), but success after three attempts was similar (combined 100%, digital 86.67%, IT 90%; p > 0.05). The time taken for successful placement was similar among groups at the first attempt, but was shorter for the combined technique for overall attempts (combined 18.33 ± 1.27 seconds, digital 27.85 ± 9.05 seconds, IT 26.89 ± 7.17 seconds; p < 0.05). There was no difference in postoperative airway morbidity.

Conclusion

PLMA insertion with combined IT and stylet technique was more frequently successful than the digital or IT technique in pediatric patients without cervical spine motion.

Keywords

laryngoscopy: difficultlaryngeal masks: ProSeal;


1. Introduction

Insertion of ProSeal laryngeal mask airway (PLMA) requires the “sniffing” position.1 The manufacturer recommends insertion of PLMA using digital manipulation (classic LMA) or with an introducer (intubating LMA), and these techniques demand flexion at the lower cervical spine and extension of the atlanto-occipital joint. This neck motion is often not possible in children with suspected cervical instability or cervical spine is externally fixed due to any reason. Several techniques have been introduced to improve the insertion success rate: the use of flexible fiberscope2; gum-elastic bougie (GEB)34; gastric tube5; and a suction catheter.6 However, none of these techniques would be easy to perform without neck movement, particularly in emergency situations. There are no studies comparing the different methods of PLMA placement without the “sniffing” position in children.

In this study, we compared a relatively new technique of PLMA insertion in children with the conventional techniques such as digital manipulation and introducer tool (IT) technique without the “sniffing” position. The new technique is a combined introducer tool and stylet technique. We compared these three techniques in terms of success rates at the first attempt and insertion time for an effective airway. Hemodynamic effects and any immediate or early complication because of insertion of the device were also noted.

2. Materials and methods

Ninety patients (American Society of Anesthesiologists physical status I or II, weight 10–20 kg) undergoing lower abdominal, inguinal, and orthopedic procedure of <1 hour while in the supine position were randomly allocated (by a computer generated randomization program) into three equal sized groups for PLMA insertion using the digital, IT, or combined IT and stylet techniques. Approval from the hospital ethics committee and written informed consent from parents were obtained. Patients were excluded if they had a known or predicted difficult airway, or were at risk of aspiration. Each technique was executed by an experienced anesthesiologist who had performed at least 50 procedures with digital manipulations or IT technique and 20 with combined IT and stylet technique.

All children were premedicated with 0.3 mg/kg of midazolam syrup 1 hour preoperatively. A standard anesthesia protocol was followed and routine monitoring was applied. Patients were preoxygenated for 3 minutes. Anesthesia was induced with sevoflurane with oxygen. Rocuronium 0.6 mg/kg was given to facilitate the insertion of PLMA. Patients were ventilated via a facemask for 3 minutes and then a pediatric collar (Paedi-Stifneck Select Collar; Laerdal Medical Corp., Wappingers Falls, NY, USA), which has been used in other studies to simulate difficult laryngoscopy,78 was applied according to the manufacturer's instructions.9 After achieving adequate depth of anesthesia, direct laryngoscopy was performed by one anesthetist using a Miller blade size 1 to grade the laryngoscopic view (Cormack and Lehane). We considered no reaction to pressure applied to both angles of the mandible and end-tidal sevoflurane concentration (EtSev) of 2.5% to indicate the adequate depth of anesthesia.10 No laryngeal manipulation was done during grading. Afterwards, the size 2 PLMA was inserted using a midline approach. Anesthesia was maintained with sevoflurane 1–2% and nitrous oxide 60% in oxygen, with positive pressure ventilation in a circle system.

The digital and IT insertion techniques were performed according to the manufacturer's instructions.1 The digital technique involves the use of the index finger to press the PLMA into, and advance it around, the palatopharyngeal curve. The IT technique involved attaching the IT (Fig. 1), using a single-handed rotational technique to press the PLMA into, and advance it around, the palatopharyngeal curve, and removing the IT. For the combined technique,11 first IT was attached to the PLMA, then a well lubricated Portex stylet was introduced via the drain tube until its distal end and a gentle C-shaped configuration of the PLMA was made (Fig. 2). With the stylet and introducer in place, the reconfigured PLMA was introduced. As soon as the device was negotiated into the palatopharyngeal curve, and before going any further, the stylet was withdrawn by about 2–3 cm and the device was placed. Both the stylet and the introducer tool were then removed. All techniques were performed with the cuff deflated using the LMA ProSeal Cuff Deflator, Teleflex Medical Asia Pte. Ltd., Battery Road, Singapore.1 Once the PLMA was inserted into the pharynx, the cuff was inflated with air until effective ventilation was established or the maximum recommended inflation volume reached. The device was fixed from maxilla to maxilla.

Fig. 1.
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Fig. 1. ProSeal laryngeal mask airway with introducer tool.
Fig. 2.
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Fig. 2. ProSeal laryngeal mask airway with combined stylet and introducer tool.

The presence or absence of oropharyngeal air leaks (detected by listening over the mouth),12 gastric air leaks (detected by listening with a stethoscope over the epigastrium),13 or an end-tidal CO2 > 45 mmHg was noted. A well-lubricated 10F gastric tube was inserted through the drain tube. Correct gastric tube placement was assessed by suction of fluid or detection of injected air by epigastric stethoscopy.

Three attempts were allowed before insertion was considered a failure. Failed insertion was defined by any of the following criteria: (1) failed passage into the pharynx; (2) malposition (air leaks or failed gastric tube insertion if pharyngeal placement successful); and (3) ineffective ventilation (end-tidal CO2 > 45 mmHg if correctly positioned). The time between picking up the prepared PLMA (cuff deflated, lubricated, IT and stylet attached) and successful placement was recorded. The reason for failed insertion was documented. If insertion failed after three attempts, the Select Collar was removed and patient was intubated. Once insertion was successful, the intracuff pressure was set at 60 cmH2O using a digital manometer (Mallinckrodt Medical, Hennef, Germany).

Hemodynamic data were collected before and immediately after PLMA insertion. Visible blood staining on the PLMA was noted at removal.

Data on failed passage into the pharynx, insertion time, and the etiology of failure were collected by an unblinded observer. Data on malpositions, effective ventilation, hypoxic episodes, and blood staining were collected by an observer blinded to the insertion technique. Statistical analysis was done using SPSS software version 17.0 (SPSS Inc., Chicago, IL, USA). Sample size was based on a projected difference of 30% among the groups for first attempt success rate, a type I error of 0.05, and a power of 0.8, and was based on studies reporting first attempt success rates.14151617 The demographic data (age, height, weight), time of insertion, and hemodynamic parameters were analyzed by analysis of variance. Insertion success was analyzed by Fisher's exact test. Complications were analyzed with Chi-square test. Data are mean (standard deviation) unless otherwise stated. Significance was taken as p < 0.05.

3. Results

There were no differences in demographic data and Cormack and Lehane score among the three groups (Table 1). Insertion was more frequently successful with the combined technique at the first attempt than the digital or IT techniques (p < 0.05), but overall success was statistically similar (Table 2). The time taken for successful placement was similar among groups at the first attempt, but was shorter for the combined technique after three attempts (p < 0.05).

Table 2.
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a Data from the seven failed insertions not included. b Drain tube air leaks and failed gastric tube insertion if pharyngeal placement successful. c End tidal CO2 > 45 mmHg if correctly positioned.

The digital technique failed in four patients and the IT technique failed in three. There were no failed uses of the combined technique. The etiology and frequency of failed insertions were similar for the digital and IT techniques (Table 2). There was neither desaturation nor any significant change in mean arterial pressure or heart rate before and after insertion of PLMA in any case (Table 3). There was no laryngospasm in any patient. There were no differences in the frequency of visible blood among groups (Table 3).

4. Discussion

The conventional techniques (digital manipulation and IT) of ProSeal LMA insertion requires the “sniffing” position of the patient, i.e., flexion at the lower cervical spine and extension of the atlanto-occipital joint.1 However, these techniques have not been proven equally efficient in situations without cervical spine motion compared to the “sniffing” position. However, this position is not possible in children where cervical spine movement is either contraindicated (e.g., head neck trauma) or not possible (cervical collar). Children with rigid neck collar may make placement of the PLMA more difficult, because the angle between the oral and pharyngeal axes becomes acute at the back of the tongue.18

In our study, the application of a rigid neck collar simulates difficult laryngoscopy by reducing both head and neck movement (necessary to align the oropharyngeal axes) and mouth opening (necessary to insert laryngoscope blade). The median Cormack and Lehane score was 2 in all three groups. The combined technique was more successful because it reduces impaction at the back of the mouth, prevents folding over of the distal cuff, and guides the distal cuff directly into its correct position in the hypopharynx.19 The distal curvature extending up to the mask tip made the negotiation of the oropharyngeal curvature easier in an otherwise fixed head and neck position. Furthermore, keeping the distal end of the stylet till the tip of the drain tube prevented the folding back of the PLMA as it met the posterior pharyngeal wall. Withdrawing the stylet by approximately 4–5 cm after negotiating the oropharyngeal curve restored the original shape of the device without disturbing progress of the tip of the PLMA towards the upper esophageal opening as confirmed by subsequent smooth passage of the gastric tube.11

The less successful first attempt insertion as well as high numbers of failure in digital group was mainly due to two reasons. First, children with the Select Collar had restricted mouth opening, which resulted in difficult PLMA insertion because there was less space to accommodate the shaft of the PLMA and finger of the operator. Second, in the digital manipulation method, the index finger rests in the junction between the shaft and the mask, leaving the larger and softer mask without any support. This causes the tip of the PLMA to fold over while negotiating it through the oropharynx in neutral position.20

The failure rate in the IT group was greater than in the combined group but less than in the digital group. Presence of the IT instead of the finger in the restricted mouth opening situation made PLMA insertion relatively easier as it consumed less space, but the failure rate was still higher than the combined group because the IT was inserted into the locating strap at the junction of the shaft and the mask. For this reason, the possibility of the PLMA tip to fold over remained the same, like the finger insertion technique, as there was no rigid structure to provide support to the larger mask of the PLMA.20 The combined technique avoids both these problems. By this technique, PLMA can be inserted through the restricted mouth opening as well as there is no chance of folding over of the tip because the rigid stylet which is extended to the tip, provides adequate support to the mask with the patient in a neutral position.11

According to Chen et al,20 insertion of the PLMA with a Flexi-Slip stylet has a higher success rate at first attempt and requires less time than the IT, but in that study, PLMA was inserted in the “sniffing” position in adult patients. Eschertzhuber et al19 conducted a study comparing GEB-guided PLMA insertion with digital and IT technique in neutral position in adult patients. They concluded that GEB-guided PLMA insertion was superior to those two conventional methods in restricted cervical spine motion and was the best back-up method in case of failure of either of those techniques. However, there are potential disadvantages with GEB-guided PLMA insertion technique.19 In this technique, laryngoscopy is mandatory for placement of the GEB in the esophagus, but laryngoscopy is difficult in this situation as there is nonalignment of oro–pharyngeal–laryngeal axes and restricted mouth opening. Besides that, the risk of esophageal trauma remains with the GEB guided technique21 as the tip of the GEB is not atraumatic, particularly in the delicate esophageal mucosa of pediatric patients. Furthermore, this technique cannot be executed by unskilled personnel because it requires laryngoscopy to place the GEB inside the esophagus.

Drolet and Girard5 and Gracia-Aguado et al6 described a similar guided technique for the PLMA using a gastric tube and a suction catheter, respectively. An advantage of the gastric tube and the suction catheter is that these are less traumatic than the GEB; however, these may not be sufficiently stiff to guide the PLMA around the back of the mouth.4 Furthermore, successful use of these techniques has not been proven in pediatric patients with immobilization of the head and neck.

There was no significant difference in heart rate and mean arterial pressure in the three groups before and after PLMA insertion. The incidence of complications (airway trauma) was very low in all cases except for blood staining in a few children in the IT and combined groups, which was neither clinically important nor statistically significant.

5. Conclusion

We conclude that combined IT and stylet technique is the best method for ProSeal LMA insertion in pediatric patients without cervical spine motion. Moreover, this technique may have a potential role during cardiopulmonary resuscitation of the pediatric patient whose neck is stabilized.


References

1
LMA Pro-Seal® Instruction Manual. Available from:
Article   CrossRef  
2
J. Brimacombe, C. Keller
Awake fiberoptic guided insertion of ProSeal laryngeal mask airway
Anesthesia, 57 (2002), p. 719
3
A. Howarth, J. Brimacombe, C. Keller
Gum elastic bougie-guided insertion of the Proseal laryngeal mask airway: A new technique
Anaesth Intens Care, 30 (2002), pp. 624-627
CrossRef  
4
J. Brimacombe, C. Keller, D.V. Judd
Gum elastic bougie-guided insertion of the ProSeal laryngeal mask airway is superior to the digital and introducer tool techniques
Anaesthesiology, 100 (2004), pp. 25-29
5
P. Drolet, M. Girard
An aid to correct positioning of the ProSeal laryngeal mask
Can J Anaesth, 48 (2001), pp. 718-719
6
R. Gracia-Aguado, J. Vinoles, J. Brimacombe, M. Vivo, R. Lopez-Estudillo, G. Ayala
Suction catheter guided insertion of the ProSeal laryngeal mask airway is superior to the digital technique
Can J Anaesth, 53 (2006), pp. 398-403
Article  
7
K. MacQuarrie, O.R. Hung, J.A. Law
Tracheal intubation using Bullard laryngoscope for patients with a simulated difficult airway
Can J Anaesth, 46 (1999), pp. 760-765
8
R. Komatsu, O. Nagata, K. Kamata, K. Yamagata, D. Sessler, M. Ozaki
Intubating laryngeal mask airway allows tracheal intubation when the cervical spine is immobilized by a rigid collar
Br J Anaesth, 93 (2004), pp. 655-659
9
H.G. Wakeling, J. Nightingale
The intubating laryngeal mask airway does not facilitate tracheal intubation in the presence of a neck collar in simulated trauma
Br J Anaesth, 84 (2000), pp. 254-256
10
M.P. Drage, J. Nunez, R.S. Vaughan, T. Asai
Jaw thrusting as a clinical test to assess the adequate depth of anaesthesia for insertion of the laryngeal mask
Anaesthesia, 51 (1996), pp. 1167-1170
11
R.M. Khan, P.K. Sharma, N. Kaul, A. Sumant
Combined use of stylet and introducer tool in ProSeal™ laryngeal mask aids insertion in halo frame immobilized patient
Internet J Anesthesiol, 18 (2008)
Article  
12
C. Keller, J. Brimacombe, K. Keller, R. Morris
A comparison of four methods for assessing airway sealing pressure with the laryngeal mask airway in adult patients
Br J Anaesth, 82 (1999), pp. 286-287
13
J. Brimacombe, C. Keller, S. Kurian, J. Myles
Reliability of epigastric auscultation to detect gastric insufflation
Br J Anaesth, 88 (2002), pp. 127-129
14
C. Keller, J. Brimacombe
Mucosal pressure and oropharyngeal leak pressure with the ProSeal versus the classic laryngeal mask airway in anaesthetized paralysed patients
Br J Anaesth, 85 (2000), pp. 262-266
15
J. Brimacombe, C. Keller
Stability of the LMA-ProSeal and standard laryngeal mask airway in different head and neck positions. A randomized crossover study
Eur J Anaesthesiol, 20 (2003), pp. 65-69
16
J. Brimacombe, C. Keller
The ProSeal laryngeal mask airway. A randomized, crossover study with the standard laryngeal mask airway in paralyzed, anesthetized patients
Anesthesiology, 93 (2000), pp. 104-109
17
N.R. Evans, S.V. Gardner, M.F. James, J.A. King, P. Roux, P. Bennett, et al.
The ProSeal laryngeal mask: results of a descriptive trial with experience of 300 cases
Br J Anaesth, 88 (2002), pp. 534-539
18
T. Asai, K. Murao, K. Shingu
Efficacy of the ProSeal laryngeal mask airway during manual in-line stabilisation of the neck
Anaesthesia, 57 (2002), pp. 918-920
19
S. Eschertzhuber, J. Brimacombe, M. Hohlrieder, K.H. Stadlbauer, C. Keller
Gum elastic bougie-guided insertion of the ProSeal laryngeal mask airway is superior to the digital and introducer tool techniques in patients with simulated difficult laryngoscopy using a rigid neck collar
Anesth Analg, 107 (2008), pp. 1253-1256
20
H.S. Chen, S.C. Yang, C.F. Chien, J. Spielberger, K.C. Hung, K.C. Chung
Insertion of the ProSeal™ laryngeal mask airway is more successful with the Flexi-Slip™ stylet than with the introducer
Can J Anaesth, 58 (2011), pp. 617-623
21
M. Kadry, M. Popat
Pharyngeal wall perforation—an unusual complication of blind intubation with a gum elastic bougie
Anaesthesia, 54 (1999), pp. 404-405

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