A randomised trial comparing the laryngeal mask airway Supreme™ with the laryngeal mask airway Unique™ in children

We conducted a randomised controlled trial comparing the laryngeal mask airway Supreme^? with the laryngeal mask airway Unique^? in children. Fifty children presenting for elective surgery were randomly assigned to receive either the laryngeal mask airway Supreme or laryngeal mask airway Unique. The outcomes measured were airway leak pressure, ease and time for insertion, insertion success rate, fibreoptic examination, incidence of gastric insufflation, ease of gastric tube placement through the laryngeal mask airway Supreme, quality of airway during anaesthetic maintenance and complications. Median (IQR [range]) time to successful device placement was shorter with the laryngeal mask airway Unique, 14.5 [13.5–16.3 (10.0–23.6)] s than with the laryngeal mask airway Supreme, 17.4 [14.8–19.8 (11.5–29.2)] s; p = 0.007. Median (IQR [range]) airway leak pressures for the laryngeal mask airway Supreme and laryngeal mask airway Unique were 20 [16–21 (12–22)] cmH₂O and 15 [14–18 (10–24)] cmH₂O, respectively (p = 0.001). The incidence of gastric insufflation was lower with the laryngeal mask airway Supreme (zero vs six patients), p = 0.01. In conclusion, the laryngeal mask airway Supreme performed as well as the laryngeal mask airway Unique and is a useful alternative for airway maintenance, particularly in children who require evacuation of gastric contents during anaesthesia.     

Comparison of laryngeal mask and intubating laryngeal mask insertion by the naïve intubator

Seventy-five inexperienced participants were timed inserting the laryngeal mask airway (LMA) and the intubating laryngeal mask (ILM) in one of five cadavers. Adequacy of ventilation was assessed on a three- point scale depending on chest expansion and air leak. Participants were also asked to intubate the trachea via the ILM. The ILM was inserted faster than the LMA (P < 0.05) with a greater proportion achieving adequate ventilation after their first attempt (P < 0.05). Tracheal intubation via the ILM was completed successfully by 67% (52 of 75) of participants. In a questionnaire, participants stated that the ILM was easier to use and the preferred device in an emergency. The results suggest that inexperienced practitioners should use the ILM rather than the LMA for emergency ventilation.      

A comparison of the Supreme™ laryngeal mask airway with the Proseal™ laryngeal mask airway in anesthetized paralyzed adult patients: a randomized crossover study

Purpose

The Supreme? laryngeal mask airway (SLMA) is a new single-use advanced form of the Proseal? laryngeal mask airway (PLMA). This study tested the hypothesis that the SLMA is equally as effective as the PLMA as a supraglottic ventilatory device in anesthetized paralyzed adult patients.

Methods

Size 4 SLMAs and PLMAs were compared in a randomized crossover study involving 60 patients aged 21-75 yr and American Society of Anesthesiologists physical status I and II. Once the patients were anesthetized and paralyzed, the SLMA and the PLMA were inserted into each patient in random order. The primary outcome measure was the laryngeal seal pressure (LSP) at an intracuff pressure of 60 cm H₂O. Secondary outcome measures included the ease of inserting the laryngeal mask airway devices (LMADs) and the fibreoptic position of the airway tube.

Results

There was no statistically significant difference in LSP between the SLMA and the PLMA. The mean LSP was 19.6 ± 5.8 cm H₂O and 20.9 ± 6.7 cm H₂O for the SLMA and the PLMA, respectively. There was a similarity between the SLMA and the PLMA regarding the number of attempts required and the duration for insertion. However, fibreoptic positioning was better with the PLMA than with the SLMA (P < 0.0001).

Conclusion

The clinical performance of the SLMA as a ventilatory device is comparable with that of the PLMA, as illustrated by the similar LSPs. The inferior position of the SLMA airway tube compared with that of the PLMA does not affect its ease of ventilation.     

Oropharyngeal leak pressure with the laryngeal mask airway Supreme™ at different intracuff pressures: a randomized controlled trial

Background

A higher oropharyngeal leak pressure (OLP) is a marker of efficacy and safety when using laryngeal mask airway devices. The new disposable laryngeal mask airway (LMA?) Supreme? has lower OLP compared with the LMA ProSeal?. Increased intracuff pressure of laryngeal mask airway devices may improve OLP but may result in more postoperative pharyngolaryngeal adverse events. This study was designed to compare the OLP of the LMA Supreme at varying intracuff pressures.

Methods

One hundred and twenty-three patients were divided randomly into three groups. General anesthesia was standardized using a propofol-fentanyl induction and desflurane in air-oxygen for maintenance. Intracuff pressures of the LMA Supreme were adjusted to 80 cm H₂O, 60 cm H₂O, and 40 cm H₂O according to group allocation. The primary outcome was OLP. Secondary outcomes included postoperative pharyngolaryngeal adverse events and the satisfaction scores of patients and anesthesiologists. The OLP was compared amongst groups using analysis of variance with Bonferroni correction. All reported P values are two-sided.

Results

The OLP with an intracuff pressure of 80 cm H₂O was significantly higher compared with 60 cm H₂O and 40 cm H₂O (26 [6] vs 20 [6] vs 18 [5] cm H₂O, respectively; P < 0.001). The incidence of postoperative pharyngolaryngeal adverse events (P = 0.6), patient satisfaction scores (P = 0.2), and anesthesiologist satisfaction scores (P = 0.8) were comparable amongst the three groups.

Conclusion

An intracuff pressure of 80 cm H₂O with the LMA Supreme is associated with a higher OLP compared with 60 cm H₂O or 40 cm H₂O without a greater incidence of postoperative pharyngolaryngeal adverse events. For a superior glottic seal when using the LMA Supreme, we recommend intracuff pressures up to 80 cm H₂O.     

Does the ProSeal laryngeal mask airway prevent aspiration of regurgitated fluid?

In this randomized, cross-over cadaver study, we determined whether a new airway device, the ProSeal laryngeal mask airway (PLMA; Laryngeal Mask Company, Henley-on-Thames, UK), prevents aspiration of regurgitated fluid. We studied five male and five female cadavers (6-24 h postmortem). The infusion set of a pressure-controlled, continuous flow pump was inserted into the upper esophagus and ligated into place. Esophageal pressure (EP) was increased in 2-cm H(2)O increments. This was performed without an airway device (control) and over a range of cuff volumes (0-40 mL) for the classic laryngeal mask airway (LMA), the PLMA with the drainage tube clamped (PLMA clamped) and unclamped (PLMA unclamped). The EP at which fluid was first seen with a fiberoptic scope in the hypopharynx (control), above or below the cuff, or in the drainage tube, was noted. Mean EP at which fluid was seen without any airway device was 9 (range 8-10) cm H(2)O. EP at which fluid was seen was always higher for the PLMA clamped and LMA compared with the control (all, P<0.0001). The mean EP at which fluid was seen for the PLMA unclamped was similar to the control at 10 (range 8-13) cm H(2)O. For the PLMA unclamped, fluid appeared from the drainage tube in all cadavers at 10-40 mL cuff volume and in 8 of 10 cadavers at zero cuff volume. Mean EP at which fluid was seen above the cuff was similar for the PLMA clamped and LMA at 0-30 mL cuff volume, but was higher for PLMA clamped at 40-mL cuff volume (81 vs 48 cm H(2)O, P = 0.006). Mean EP at which fluid was seen below the cuff was similar at 0-10 mL cuff volume, but was higher for the PLMA clamped at 20, 30, and 40 mL cuff volume (62, 68, 73 vs. 46, 46, 46 cm H(2)O, respectively, P<0.04). For the PLMA clamped and the LMA, fluid appeared simultaneously above and below the cuff at all cuff volumes. We concluded that in the cadaver model, the correctly placed PLMA allows fluid in the esophagus to bypass the pharynx and mouth when the drainage tube is open. Both the LMA, and PLMA with a closed drainage tube, attenuate liquid flow between the esophagus and pharynx. This may have implications for airway protection in unconscious patients.     

The proseal™laryngeal mask airway: a review of the literature

PURPOSE: To analyze and summarize the published literature relating to the ProSeal LMA (PLMA): a modification of the "classic LMA" (cLMA) with an esophageal drain tube (DT), designed to improve controlled ventilation, airway protection and diagnosis of misplacement. SOURCE: Articles identified through Medline and EMBASE searches using keywords "Proseal", "ProSeal" and "PLMA". Hand searches of these articles and major anesthetic journals from January 1998 to March 2005. PRINCIPAL FINDINGS: Searches identified 59 randomized controlled trials or clinical studies and 79 other publications. Compared to the cLMA, PLMA insertion takes a few seconds longer. First attempt insertion success for the PLMA is lower, but overall success is equivalent. Airway seal is improved by 50%. The DT enables early diagnosis of mask misplacement, allows gastric drainage, reduces gastric inflation and may vent regurgitated stomach contents. Evidence suggests, but does not prove, that the correctly placed PLMA reduces aspiration risk compared with the cLMA. PLMA use is associated with less coughing and less hemodynamic disturbance than use of a tracheal tube (TT). Comparative trials of the PLMA with other supraglottic airways favour the PLMA. Clinicians have extended the use of the PLMA inside and outside the operating theatre including use for difficult airway management and airway rescue. CONCLUSIONS: The PLMA has similar insertion characteristics and complications to other laryngeal masks. The DT enables rapid diagnosis of misplacement. The PLMA offers significant benefits over both the cLMA and TT in some clinical circumstances. These and clinical experience with the PLMA are discussed.     

Tongue numbness following laryngeal mask airway Supreme™ and i-gel™ insertion: two case reports

We present two cases of transient lingual nerve injury that were associated with the use of a laryngeal mask airway Supreme? (The Laryngeal Mask Company, Singapore) during lumbar discectomy in a 43‐year‐old female and i‐gel? (Intersurgical, Berkshire, UK) during ovum pick up in a 33‐year‐old female. They presented with numbness at the tip of their tongues and spontaneously and fully recovered 2 weeks after their operations.     

Use of the intubating laryngeal mask airway: are muscle relaxants necessary?

BACKGROUND: The intubating laryngeal mask airway (ILMA) is designed to facilitate blind tracheal intubation. The effect of a muscle relaxant on the ability to perform tracheal intubation through the ILMA device has not been previously evaluated. This randomized, double-blind, placebo-controlled study was designed to evaluate rocuronium, 0.2 or 0.4 mg/kg administered intravenously, on the success rate and incidence of complications associated with ILMA-assisted tracheal intubation. METHODS: A total of 75 healthy patients were induced with propofol 2 mg/kg and fentanyl 1 microg/kg intravenously. After insertion of the ILMA device, patients were administered either saline, rocuronium 0.2 mg/kg, or rocuronium 0.4 mg/kg in a total volume of 5 ml. At 90 s after administration of the study drug, tracheal intubation was attempted using a disposable polyvinyl tube. If unsuccessful, a reusable silicone tube was tried. In addition to recording the time and number of attempts required to secure the airway, the incidence of complications during placement of the tracheal tube and removal of the ILMA were noted. RESULTS: Tracheal intubation was successful in 76-96% of the patients. The overall success rates and times required to secure the airway were similar in all three treatment groups. The high-dose rocuronium group experienced less patient movement (8 vs. 28 and 48%) and coughing (12 vs. 20 and 52%) than the low-dose rocuronium and saline groups, respectively. Use of rocuronium was also associated with a dose-related decrease in the requirement for supplemental bolus doses of propofol during intubation and removal of the ILMA device. CONCLUSIONS: Use of rocuronium did not significantly improve the success rate in performing tracheal intubation through the ILMA. However, it produced dose-related decreases in coughing and movement after tracheal intubation and reduced difficulties associated with removal of the ILMA device.     

Accuracy of ProSeal™ laryngeal mask airway intracuff pressure estimation using finger palpation technique - a prospective, observational study

The incidence of pharyngolaryngeal adverse events associated with laryngeal mask airways can be reduced by the use of manometry to limit the laryngeal mask airway intracuff pressures. We conducted a prospective, observational study in 80 patients undergoing general anaesthesia with the ProSeal? laryngeal mask airway to determine the accuracy of a finger palpation technique compared to actual readings obtained from a hand-held manometer by different anaesthesia personnel. The strength of association of estimated versus actual intracuff pressures, R, for nurse anaesthesia assistants, junior anaesthetists and senior anaesthetists were 0.21 (weak), 0.35 (moderate) and 0.78 (strong) respectively. Subgroup analysis showed that anaesthetists with more than three years of experience were more accurate than those with less than three years of experience. The actual versus estimated intracuff pressures were 4±17 vs 19±27 cmH2O (P value <0.001) respectively. In all groups, the palpation technique tended to underestimate the actual intracuff pressure by a mean of 10.3 cmH2O. Palpation accuracy decreased when actual intracuff pressures were >80 cmH2O. These findings suggest that cuff pressure manometry should be recommended as standard of care with the use of laryngeal mask airways.