Abstract
The ProSeal™ laryngeal mask airway (PLMA) offers a more effective seal and is easier for gastric tube placement to prevent aspiration than the classical laryngeal mask airway. However, it is more difficult to insert with the digital and introducer tooling techniques. The Rusch Flexi-Slip stylet (RFSS) is an accessory intubation tool that consists of a malleable coated wire and a soft atraumatic tip. It has been reported that it can facilitate easier insertion of the PLMA. Here, we report two cases in which the PLMA could not be inserted correctly on the initial attempts, and with successful placement of the PLMA after using an RFSS. In the first case, three attempts to insert the PLMA with the digital and introducer tooling techniques were unsuccessful. The second case was known to be difficult for PLMA placement because, in a previous operation, PLMA insertion for general anesthesia was unsuccessful, and in that instance required endotracheal intubation for general anesthesia. In both cases, the PLMA was successfully inserted using the RFSS technique, without difficulty. The RFSS technique offers several advantages for PLMA insertion, including the provision of effective support and a soft tip for the PLMA insertion. Other techniques to facilitate the insertion of the PLMA, including priming the drain tube with a guide are discussed. We recommend that the RFSS technique offers an effective method for cases with difficult insertion of the PLMA.
Keywords
laryngeal masks: ProSeal™; Rusch Flexi-Slip stylet;
1. Introduction
The ProSeal™ laryngeal mask airway (PLMA; Laryngeal Mask Company North America, San Diego, CA, USA) was first introduced by Brain et al in 2000.1 They re-ported that the PLMA can form a more effective seal than the classic laryngeal mask airway and facilitate gastric tube placement to prevent aspiration. Traditionally, the PLMA may be inserted with a fin-ger, as for the classic laryngeal mask airway, or with an introducer tool, as described in the manu-facturer’s instructions.2 However, because it lacks a semi-rigid backplate, the PLMA cuff is softer than or-dinary laryngeal mask airway cuffs and folding-over malposition is more likely to occur with the PLMA.3 A new technique using the Rusch Flexi-Slip stylet (RFSS; no. 503000-4.3/5.6; Willy Ruesch GmbH, Kernen, Germany) was recently reported to facili-tate the insertion of the PLMA.4 The RFSS tech-nique provides an internal supporting structure to prevent folding of the soft cuff and thus avoid malposition. Furthermore, a 90º angle of the air-way tube that is conformable to the anatomy of the oropharynx can facilitate correct insertion. We present two cases in which correct insertion of the PLMA was not possible with traditional tech-niques, but was successfully remedied using the RFSS technique.
2. Case Reports
2.1. Case
A 38-year-old male patient (body weight, 83 kg; height, 161 cm) was scheduled for elective left herniorrhaphy under general anesthesia. His past history included hypertension with medical control for 3 years. Preoperative airway evaluation revealed no airway anomalies. In the operating room, the pa-tient was given 150 μg of fentanyl, 450 mg of thiamy-lal, and 100 mg of 2% lidocaine to induce anesthesia. A size 5 PLMA was inserted with the introducer tool technique2 when there was no response to jaw thrust.5 The initial insertion of the PLMA failed be-cause it was difficult to slide the PLMA into the pharynx. On the second attempt, a slight lateral approach was used but tactile resistance was still felt at the back of the mouth and the bite block almost protruded from the mouth. On the third at-tempt, digital manipulation2 was unsuccessfully used. Some blood was noted on the PLMA after the three attempts. Ventilation was well maintained with 100% oxygen via a facemask without hypox-emia (SpO2 < 90%) between each insertion. At the fourth approach, the PLMA was successfully inserted by applying the RFSS technique,4 which involved the following steps: (1) the stylet was inserted into the proximal end of the PLMA drainage tube and pushed forward until the tip reached approximately 1.0−2.0 cm from the distal end of the drain tube; (2) after bending the proximal end of the stylet back-ward to 180º, the PLMA/stylet setting was bent to a 90º angle around the laryngeal portion of the PLMA (Figure 1); (3) the PLMA/stylet setting was ad-vanced into the mouth and the tip was rotated cau-dad into the different axes of the oropharynx with a simple wrist motion, similar to that used to insert a laryngoscope behind the base of the tongue; and (4) the stylet was removed while the laryngeal mask passed the base of the tongue. After insertion, the cuff was inflated with air to a pressure of 60 cmH2O. The oropharyngeal leak pressure was 36 cmH2O, and no air leakage was detected from the drainage tube. Positive pressure ventilation was started at a tidal volume of 600 mL and a respiratory rate of 12 breaths/min. The peak airway pressure was 25 cmH2O. A well-lubricated 14-F suction tube was inserted through the drainage tube. Anesthesia was maintained with 3% sevoflurane in oxygen and an additional dose of cisatracurium (4 mg) was given for surgical relaxation. SpO2 was maintained throughout the surgical procedure at around 100% with end-tidal carbon dioxide < 45 mmHg.
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At the end of the surgical procedure, anesthesia was discontinued and the PLMA was removed as the patient’s reflexes returned. The patient was then transferred to the recovery room. In the recovery room, the patient complained of mild throat dis-comfort and dysphagia. Postoperative pain control was provided by intravenous meperidine (50 mg). One hour later, the patient felt better and was re-turned to the ward. At the postanesthetic visit the next day, there were no further complaints and the patient’s sore throat and dysphagia were improving. On postanesthetic day 3, the pharyngolaryngeal dis-comfort had completely abated. The patient was discharged 4 days later from hospital without any sequelae.
2.2. Case 2
A 77-year-old male (body weight, 108 kg; height, 165 cm) with a varus deformity of the left knee joint was scheduled for total left knee replace-ment. Contralateral total knee replacement had been carried out 11 months earlier under general anesthesia. In the previous general anesthesia, the PLMA could not be inserted, despite more than three attempts using various techniques. The pa-tient ultimately required endotracheal intubation for general anesthesia.
At this admission, the patient refused regional anesthesia for personal reasons. In compliance with the patient’s request, it was decided to induce gen-eral anesthesia after inserting the PLMA using the new RFSS technique. After the patient was preoxy-genated for 5 minutes, anesthesia was induced with 150 μg of fentanyl, 200 mg of propofol, 4 mg of cisa-tracurium, and 60 mg of 2% lidocaine. A size 5 PLMA was inserted using the RFSS technique because of unresponsiveness to the jaw thrust.5 The insertion of the PLMA was smooth and uneventful. The cuff was inflated with air to a pressure of 60 cmH2O, and the lungs were easily inflated. Oro pharyngeal leak pressure was 32 cmH2O, and there was no air leak-age from the drainage tube. After inserting a 14-F suction tube through the drainage tube, positive pressure ventilation was started at a tidal volume of 700 mL and a respiratory rate of 12 breaths/min. The peak airway pressure was 23 cmH2O and the end-tidal carbon dioxide was maintained at < 45 mmHg. Anesthesia was maintained with 6% desflurane in oxygen. At the end of the operation, the PLMA was removed once the patient was fully awake. No blood was visible on the PLMA. In the recovery room, the patient only complained of discomfort in his left knee and was returned to the ward 1 hour later. There were no complaints related to anesthesia during postoperative visits. He was discharged un-eventfully from hospital 6 days later.
3. Discussion
The PLMA has a second posterior cuff to improve the seal and a drainage tube to reduce gastric inflation and regurgitation.1 Although the manufacturer rec-ommends digital manipulation or an introducer tool to insert the PLMA, the success rate of both tech-niques on the first attempt is lower than that classic laryngeal mask airways.6−8 The lack of a supporting structure in the soft laryngeal mask means that the insertion may be impeded due to impaction of the PLMA at the back of the mouth or due to folding of the cuff.
The PLMA drainage tube communicates with the upper esophageal sphincter and permits vent-ing of the stomach and blind insertion of a stand-ard gastric tube. In addition to inserting a gastric tube, the drainage tube provides an additional value to facilitate PLMA insertion. Many techniques have been reported to facilitate PLMA insertion,8−10 most of which involve priming the drainage tube with a guide, which enables the PLMA to slide into place along the guide. Blind advancement of a suc-tion catheter was reported to show a higher suc-cess rate and cause less mouth trauma than the digital technique in one series.9 However, the suc-tion tube may be insufficiently rigid to guide the distal cuff around the oropharynx, particularly if the oropharyngeal axis is less than 90º, and impac-tion can still occur. Furthermore, iatrogenic inju-ries of the upper gastrointestinal tract are often associated with blind insertion of the flexible tubes.11 Brimacombe et al reported that PLMA in-sertion by direct laryngoscopic placement of a gum-elastic bougie into the esophagus offered a very high success rate.8 It is necessary to place the stiff gum elastic bougie under direct vision using a laryngoscope to avoid potential complications as-sociated with blind intubation.12 On the other hand, this technique may be difficult to perform by clinicians with less laryngoscopic experience or in patients whose laryngeal structure cannot be easily viewed by laryngoscopy.
The RFSS is made of a malleable coated wire that retains its shape after adjustment to facili-tate endotracheal intubation. The RFSS also has a soft atraumatic tip that helps to prevent tissue damage during insertion. Yodfat13 reported that the creation of a 90º angle on a rigid stylet placed close to the laryngeal portion of the laryngeal mask airway improves the rate of successful inser-tion. The same concept was applied in the devel-opment of the PLMA introducer tool and the Ambu laryngeal mask.14 By placing the airway tube and the internal supporting stylet at a 90º angle and the use of an internal supporting stylet, the RFSS technique not only provides a contour to facilitate insertion of the PLMA, but also prevents the tip of the mask from being folded backward.4 These ad-vantages are very useful in patients who tend to experience impaction of the PLMA at the back of the mouth. The unsuccessful insertion in our first case was largely due to folding of the cuff and im-paction of the PLMA at the back of the mouth. This malposition occurs in approximately 3% of cases when the PLMA is inserted using the digital or the introducer tool techniques because the backplate is softer, and it was usually folded in the mid por-tion of the bowl.3 By partially supporting the la-ryngeal part of the RFSS, the laryngeal mask is strong enough to pass through the dropped tongue without folding the PLMA. Once the laryngeal mask is placed under the base of the tongue, the inflation of the cuff will adjust the laryngeal mask to the optimal position to match the contours of the pha-ryngeal and laryngeal surfaces. The soft distal end of the cuff could prevent the oropharynx from being harmed during the insertion. Postoperative discom-fort, as in Case 1, is probably due to repeated inser-tion of the PLMA rather than inserting the soft-tipped RFSS. Further studies are needed to confirm this hypothesis.
Our second case was a patient with morbid obes-ity (body mass index, 39.7 kg/m2). This patient had a past history of unsuccessful insertion of the PLMA using traditional techniques. The placement of a classic laryngeal mask airway is usually contraindi-cated in grossly or morbidly obese patients be-cause of the increased risk of regurgitation and the need for high airway pressure ventilation.15 The PLMA forms a better seal than the classical laryngeal mask airway and its drainage tube will protect the lungs from regurgitated gastric con-tents if it is correctly placed.16 Keller et al’s study illustrated that the PLMA could be used as an al-ternative ventilatory device in grossly and morbidly obese patients.17 In this patient, we considered that using the PLMA for the surgical procedure was appropriate if it could be correctly placed. The RFSS technique was used in this case because of its suitability in overcoming difficult insertion of the PLMA and the procedure was uneventful. No post-operative complications were noted.In conclusion, we have presented two cases in whom PLMA insertion was initially unsuccessful using standard techniques, but the insertion was successful when the RFSS technique was used. This new technique provides an effective method for patients who have sustained or had previously ex-perienced unsuccessful PLMA insertion using tradi-tional techniques. The PLMA has been confirmed to be useful for the management of difficult air-way. The new technique may improve the rate of successful PLMA use in difficult cases.
Acknowledgments
This study was financially supported by the Depart-ment of Anesthesiology, E-Da Hospital.