One hundred forty patients were included in the final analysis: 66 in the FAST-guided group and 74 in the IT-assisted group. The incidence of correct alignment of the airway tube and the drain tube did not differ significantly between the groups. There were no significant differences in ease of insertion or hemodynamic responses to insertion, except that the incidence of postoperative sore throat was significantly higher in the FAST group on the first postoperative day Peer Review reports.
The ProSeal laryngeal mask airway LMA; Orthofix, Maidenhead, UK is a laryngeal mask with a modified cuff that incorporates a drainage tube to improve the quality of the seal while reducing the risk of pulmonary aspiration and gastric insufflation [ 1 — 3 ].
The manufacturer recommends that the ProSeal LMA be inserted using either manipulation with the fingers or a curved metal introducer. Consequently, a variety of techniques has been developed to facilitate insertion of the ProSeal LMA, including priming the drain tube with a guiding instrument such as a suction catheter [ 6 ], a gastric tube [ 7 ], a gum elastic Bougie [ 8 ], a Flexi-Slip stylet [ 9 ] and even a fiberoptic bronchoscope [ 10 , 11 ].
Most are based on blind catheter or tube insertion, and although a fiberoptic bronchoscope enables the intraoral structures to be viewed, it is too expensive and cumbersome to be used in routine practice. It has been reported to facilitate tracheal intubation with an intubating LMA [ 12 ], and thus we hypothesized that it might also be advantageous for ProSeal LMA insertion.
We determined that the LMA was correctly positioned by checking its alignment with the glottic and esophageal openings using a fiberoptic bronchoscope. We evaluated both techniques in terms of success rates, insertion times, insertion difficulty, hemodynamic response to insertion and the incidence of postoperative sore throat.
Exclusion criteria included an anticipated difficult airway, morbid obesity, inadequate fasting, and pre-existing sore throat or hoarseness. Patients were allocated randomly into one of two groups using a computer-generated random number table. None of the patients was aware of the insertion method used. No premedication was administered. In the operating room, heart rate, blood pressure and arterial oxygen saturation were recorded at baseline and then every 5 min thereafter.
Each patient was anesthetized in the supine position with the head resting on a 7-cm high pillow. The cuff was fully deflated and the back surface lubricated. Fentanyl 0. Thereafter, sevoflurane was administered at an end-tidal concentration of 1. The atraumatic tip of the stylet can be seen protruding from the distal end of the drainage tube; the flexible portion of the stylet extends 5—6 cm beyond the cuff.
Two attempts were allowed before insertion was considered to have failed. Insertion time was defined as time elapsed from opening the mouth until the ProSeal LMA was connected to the anesthetic breathing circuit. Ease of insertion was graded as smooth, mildly resistant or requiring a second attempt. The glottic view was scored using a five-point scale Table 1 based on previous studies [ 2 , 13 , 14 ]. The alignment of the tip of the drain tube with the esophageal opening was evaluated using a fiberoptic bronchoscope inserted in the drain tube.
The view of the esophagus was scored using a three-point scale Table 1. Postoperative sore throat was recorded in the postoperative care unit and on the following morning. All parameters were recorded and data analyzed by an investigator blinded to the insertion technique. Study design was informed by the findings of a previous report of Bougie-guided LMA insertion time [ 8 ], and sample size estimated on the basis of one control per experimental subject, a difference in mean insertion time of 10 seconds between groups, normally distributed data and a standard deviation of 17 seconds.
At least 62 subjects were needed in each group based on a type I error 0. We allocated 80 patients to each group to take into account the possibility of surgical problems and failed ProSeal LMA insertion requiring patients to be excluded from analysis of total insertion time to find out reasons.
We compared patient characteristics, insertion time, insertion attempts, adverse effects and complications between the groups using the two-sample t -test for numerical variables and the Chi-square test for categorical variables. From June to Dec , fourteen patients in the FAST group were excluded from final analysis seven owing to changes in the surgical plan, four withdraw consent, and three owing to failed insertion.
Of the three failed insertions, two in the FAST group were as a consequence of the cuff folding in the oropharynx and one owing to an unexpectedly blurred view through the FAST device during insertion. Six patients in the IT group were excluded from final analysis three owing to a change in surgical plan, two withdraw consent, and one owing to a failed insertion caused by folding back of the ProSeal LMA and air leak.
The hemodynamic responses to ProSeal LMA insertion were broadly comparable between the groups: there were no significance differences in heart rate or mean arterial pressure Table 3. The ability to visualize the glottic structures and esophageal opening was also not significantly different between the groups Table 4. We found that the ProSeal LMA can be properly positioned using either the FAST-guided technique or IT techniques; fiberoptic bronchoscopy showed that the mask aligned correctly with the glottis and esophagus in the majority of cases.
Nevertheless, the FAST technique took significantly longer and the incidence of sore throat on the second postoperative day was significantly higher than the traditional IT technique. We can therefore draw the conclusion that the direct vision FAST device does not appear to have any advantages over the traditional introducer for ProSeal LMA insertion. A popular method of facilitating ProSeal LMA insertion is to use a gum-elastic Bougie in the drainage tube together with a laryngoscope, which allows the tip to be correctly positioned in the esophagus.
This technique is recommended as a second-line backup means of directly visualizing the upper airway [ 8 ]. The Bougie provides sufficient rigidity to guide the cuff directly into the pharynx without folding [ 8 , 15 , 16 ].
However, without laryngoscopic assistance, blind insertion is reported to have caused pharyngeal wall perforation [ 17 ]. Gas leak and gastric insufflation during controlled ventilation: face mask versus laryngeal mask airway. Respiratory mechanics, gastric insufflation pressure, and air leakage of the laryngeal mask airway. Anesth Analg ; —8. Clinical significance of pulmonary aspiration during the perioperative period. Anesthesiology ; 56— Brimacombe J, Keller C. Responses of the gastroesophageal junctional zone to increases in abdominal pressure.
Can J Surg ; 9: 32—8. Gastric distension: a mechanism for postprandial gastroesophageal reflux. Gastroenterology ; — Textbook of Medical Physiology, 10th ed.
Philadelphia: WB Saunders Company, Download references. Roger Maltby, Michael T. Beriault, Neil C. You can also search for this author in PubMed Google Scholar. Correspondence to J. Roger Maltby. Reprints and Permissions.
Maltby, J. Can J Anesth 50, 71—77 Download citation. Accepted : 14 October Issue Date : January Anyone you share the following link with will be able to read this content:. Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative. Skip to main content. Search SpringerLink Search. Following failed attempts at intubation, a size 5 PLMA was successful in securing his airway and surgery proceeded uneventfully.
Conclusions: The correctly placed PLMA has potential advantages over the cLMA for airway rescue in the circumstance of failed emergency intubation in a patient with a potentially full stomach. In the two cases reported, the PLMA provided effective rescue of the airway.
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