The laryngeal mask airway Unique versus the Soft Seal laryngeal mask: a randomized, crossover study in paralyzed, anesthetized patients

Laryngeal mask airway Unique™ position in paediatric patients undergoing magnetic resonance imaging (MRI): prospective observational study

Background

Laryngeal mask UNIQUE® (LMAU) is supraglottic airway device with good clinical performance and low failure rate. Little is known about the ideal position of the LMAU on the magnetic resonance imaging (MRI) and whether radiological malposition can be associated with clinical performance (audible leak) in children. The primary aim of the study was to evaluate incidence of the radiologic malposition of the LMAU according to size. The secondary outcome was the clinical performance and associated complications (1st attempt success rate, audible leak) in LMAUs in correct position vs. radiologically misplaced LMAUs.

Methods

In prospective observational study, all paediatric patients undergoing MRI of the brain under general anaesthesia with the LMAU were included (1.9.2016–16.5.2017). The radiologically correct position: LMAU in hypopharynx, proximal cuff opposite to the C1 or C2 and distance A (proximal cuff end and aditus laryngis) ≤ distance B (distal cuff end and aditus laryngis). Malposition A: LMAU outside the hypopharynx. Malposition B: proximal cuff outside C1-C2. Malposition C: distance A ≥ distance B. We measured distances on the MRI image. Malposition incidence between LMAU sizes and first attempt success rate in trainees and consultant groups was compared using Fisher exact test, difference in incidence of malpositions using McNemar test and difference in leakage according to radiological position using two-sample binomial test.

Results

Overall 202 paediatric patients were included. The incidence of radiologically defined malposition was 26.2% (n = 53). Laryngeal mask was successfully inserted on the 1st attempt in 91.1% (n = 184) cases. Audible leak was detected in 3.5% (n = 7) patients. The radiologically defined malposition was present in 42.9% (n = 3) cases with audible leak. The rate of associated complications was 1.5% (n = 3): laryngospasm, desaturation, cough. In 4.0% (n = 8) the LMAU was soiled from blood.

Higher incidence of radiological malposition was in LMAU 1.0, 1.5 and LMAU 3, 4 compared to LMAU 2 or LMAU 2.5 (p < 0.001).

Conclusion

Malposition was not associated with impaired clinical performance (audible leak, complications) of the LMAU or the need for alternative airway management.

Trial registration

Clinicaltrials.gov  (NCT02940652) Registered 18 October 18 2016.

An update on newer pediatric supraglottic airways with recommendations for clinical use

Supraglottic airways are an established part of routine and emergency pediatric airway management, including use in difficult airways and neonatal resuscitation. With the introduction of newer supraglottic airways in children, efficacy can only be determined by comparing these devices with those that are already well established (laryngeal mask airway Classic and laryngeal mask airway ProSeal). This narrative review aims to present the current literature on these newer supraglottic airways and give recommendations for their use in various clinical scenarios based on the existing evidence.

Basic life support trained nurses ventilate more efficiently with laryngeal mask supreme than with facemask or laryngeal tube suction-disposable--a prospective, randomized clinical trial

OBJECTIVE

In some emergency situations resuscitation and ventilation may have to be performed by basic life support trained personnel, especially in rural areas where arrival of advanced life support teams can be delayed. The use of advanced airway devices such as endotracheal intubation has been deemphasized for basically-trained personnel, but it is unclear whether supraglottic airway devices are advisable over traditional mask-ventilation.

METHODS

In this prospective, randomized clinical single-centre trial we compared airway management and ventilation performed by nurses using facemask, laryngeal mask Supreme (LMA-S) and laryngeal tube suction-disposable (LTS-D). Basic life support trained nurses (n=20) received one-hour practical training with each device. ASA 1-2 patients scheduled for elective surgery were included (n=150). After induction of anaesthesia and neuromuscular block nurses had two 90-second attempts to manage the airway and ventilate the patient with volume-controlled ventilation.

RESULTS

Ventilation failed in 34% of patients with facemask, 2% with LMA-S and 22% with LTS-D (P<0.001). In patients who could be ventilated successfully mean tidal volume was 240±210 ml with facemask, 470±120 ml with LMA-S and 470±140 ml with LTS-D (P<0.001). Leak pressure was lower with LMA-S (23.3±10.8 cm H2O, 95% CI 20.2-26.4) than with LTS-D (28.9±13.9 cm·H2O, 95% CI 24.4-33.4; P=0.047).

CONCLUSIONS

After one hour of introductory training, nurses were able to use LMA-S more effectively than facemask and LTS-D. High ventilation failure rates with facemask and LTS-D may indicate that additional training is required to perform airway management adequately with these devices. High-level trials are needed to confirm these results in cardiac arrest patients.

Comparison of the Proseal LMA and intersurgical I-gel during gynecological laparoscopy

BACKGROUND

The relatively recently developed I-gel (Intersurgical Ltd., Workingham, England) is a supraglottic airway device designed for single-use that, unlike conventional LMAs, does not require an inflatable cuff. In addition, the I-gel, much like the Proseal LMA (PLMA), has a gastric drainage tube associated with an upper tube for decompression of the stomach, thereby avoiding acid reflux and decreasing the risk of pulmonary absorption. The purpose of this study was to compare PLMA and I-gel devices in patients undergoing gynecological laparoscopy based on sealing pressure before and during pneumoperitoneum, insertion time, and gas exchange.

METHODS

Following Institutional Review Board approval and written informed consent, 30 adult patients were randomly allocated to one of two groups (the PLMA or I-gel group). In each case, insertion time and number of attempts were recorded. After successful insertion, airway leak pressure was measured.

RESULTS

Successful insertion and mechanical ventilation with both supraglottic airway devices was achieved on the first attempt in all 30 patients, and there were no significant differences with respect to insertion time. Likewise, leak pressure did not vary significantly either between or within groups after CO(2) insufflation. In addition, differences between leak volume and leak fraction between groups were not significant.

CONCLUSIONS

The results of our study indicate that the I-gel is a reasonable alternative to the PLMA for controlled ventilation during laparoscopic gynecologic surgery.

Randomised Comparison of the AMBU AuraOnce Laryngeal Mask and the LMA Unique Laryngeal Mask Airway in Spontaneously Breathing Adults

We conducted a randomised single-blind controlled trial comparing the LMA-Unique (LMAU) and the AMBU AuraOnce (AMBU) disposable laryngeal mask in spontaneously breathing adult patients undergoing general anaesthesia. Eighty-two adult patients (ASA status I–IV) were randomly allocated to receive the LMAU or AMBU and were blinded to device selection. Patients received a standardized anesthetic and all airway devices were inserted by trained anaesthetists. Size selection was guided by manufacturer recommendations. All data were collected by a single, unblinded observer. When compared with the LMAU, the AMBU produced significantly higher airway sealing pressures (AMBU 20 ± 6; LMAU 15 ± 7 cm H₂O; P = 0.001). There was no statistical difference between the two devices for overall success rate, insertion time, number of adjustments, laryngeal alignment, blood-staining, and sore throat (P ≥ 0.05). The AMBU AuraOnce disposable laryngeal mask provided a higher oropharyngeal leak pressure compared to the LMA Unique in spontaneously breathing adult patients.

A randomised trial comparing the i-gel (TM) with the LMA Classic (TM) in children

We performed a prospective, randomised trial comparing the i-gel(TM) with the LMA Classic(TM) in children undergoing general anaesthesia. Ninety-nine healthy patients were randomly assigned to either the i-gel or the LMA Classic. The outcomes measured were airway leak pressure, ease of insertion, time taken for insertion, fibreoptic examination and complications. Median (IQR [range]) time to successful device placement was shorter with the i-gel (17.0 (13.8-20.0 [10.0-20.0]) s) compared with the LMA Classic (21.0 (17.5-25.0 [15.0-70.0]) s, p = 0.002). There was no significant difference in oropharyngeal leak pressure between the two devices. A good fibreoptic view of the glottis was obtained in 74% of the i-gel group and in 43% of the LMA Classic group (p < 0.001). There were no significant complications. In conclusion, the i-gel provided a similar leak pressure, but a shorter insertion time and improved glottic view compared with the LMA Classic in children.

The air-Q(®) intubating laryngeal airway vs the LMA-ProSeal(TM) : a prospective, randomised trial of airway seal pressure

We performed a prospective, open-label, randomised controlled trial comparing the air-Q(®) against the LMA-ProSeal™ in adults undergoing general anaesthesia. One hundred subjects (American Society of Anesthesiologists physical status 1-3) presenting for elective, outpatient surgery were randomly assigned to 52 air-Q(®) and 48 ProSeal devices. The primary study endpoint was airway seal pressure. Oropharyngolaryngeal morbidity was assessed secondarily. Mean (SD) airway seal pressures for the air-Q(®) and ProSeal were 30 (7) cmH (2) O and 30 (6) cmH(2) O, respectively (p = 0.47). Postoperative sore throat was more common with the air-Q(®) (46% vs 38%, p = 0.03) as was pain on swallowing (30% vs 5%, p = 0.01). In conclusion, the air-Q(®) performs well as a primary airway during the maintenance of general anaesthesia with an airway seal pressure similar to that of the ProSeal, but with a higher incidence of postoperative oropharyngolaryngeal complaints.

Randomized crossover comparison between the i-gel and the LMA-Unique in anaesthetized, paralysed adults

BACKGROUND

The i-gel differs from other supraglottic airway devices, in that it has a softer, non-inflatable cuff. This study was designed to compare the performance of the i-gel and the LMA-Unique (LMA-U) when used during anaesthesia in paralysed patients.

METHODS

Both devices were studied in 39 anaesthetized, paralysed patients in a randomized crossover trial. The primary outcome was airway leak pressure. Secondary outcomes included time to insertion, the number of insertion and reposition attempts, leak volumes, and leak fractions.

RESULTS

There was no significant difference between the airway leak pressures of the two devices [median (IQR) leak pressures 25 (22-30) vs 22 (20-28) cm H(2)O for the i-gel and LMA-U, respectively; P=0.083, 95% CI of the mean difference -0.32 to 4.88 cm H(2)O]. The median (IQR) insertion time for the i-gel was significantly less than for the LMA-U [12.2 (9.7-14.3) vs 15.2 (13.2-17.3) s; P=0.007]. All the LMA-U devices and 38 of 39 i-gel airways were inserted at the first attempt. The number of manipulations required after insertion to achieve a clear airway was the same in both the groups (four in each). There were no statistically significant differences in leak volumes or leak fractions during controlled ventilation.

CONCLUSIONS

We found no difference in leak pressures and success rate of first-time insertion between the i-gel and the LMA-U. Time to successful insertion was significantly shorter for the i-gel. We conclude that the i-gel provides a reasonable alternative to the LMA-U for controlled ventilation during anaesthesia.

The Soft Seal disposable laryngeal mask airway in adults: comparison of two insertion techniques without intra-oral manipulation

We investigated whether insertion of the disposable Soft Seal laryngeal mask airway (SSLM) was successful without intra-oral digital manipulation. One hundred patients undergoing anaesthesia using the SSLM were randomly assigned into two groups. Insertion was performed by either a direct or a rotational technique, both without intra-oral digital manipulation. The primary outcome measure was successful insertion at first attempt. Other outcomes included insertion time, fibreoptic assessment of the airway view and airway morbidity. The first attempt success rate was higher (98%) with the direct technique than with the rotational technique (75%; p = 0.002) but insertion time was faster with the latter method (mean [range] 15 [8-50] s) than with the direct method (20 [8-56] s; p = 0.035). Fibreoptic assessment and airway morbidity were similar in both groups. We conclude that the SSLM can be successfully inserted without intra-oral digital manipulation.

Comparison of the CobraPLA (Cobra Perilaryngeal Airway) and the Laryngeal Mask Airway Unique in children under pressure controlled ventilation

BACKGROUND

The Laryngeal Mask Airway-Unique (LMAU) and CobraPLA (Cobra Perilaryngeal Airway) are supraglottic airway devices. There are no published studies comparing these devices in children breathing with pressure controlled ventilation (PCV).

METHODS

Eighty pediatric patients, scheduled for elective general surgery of short duration, were randomly assigned to have either a CobraPLA or a LMAU used for airway management using PCV. We compared the devices with respect to (i) ability to form an effective cuff seal, (ii) oxygenation, (iii) endtidal carbon dioxide level, (iv) time to achieve an effective airway, (v) airway interventions required for insertion, (vi) fiberoptic score, (vii) respiratory variables and (vii) adverse events.

RESULTS

Cuff seal pressure was significantly higher for CobraPLA (27.08 +/- 4.15 cmH(2)O) than for LMAU (20.91 +/- 2.47 cmH(2)O). Oxygenation was similar in both groups while the mean endtidal CO(2) in the CobraPLA group was significantly higher than in the LMAU group (36.47 +/- 1.93 mmHg vs 34.71 +/- 3.05 mmHg, P = 0.021). Time and ease of insertion were similar, with CobraPLA requiring more frequent jaw lift and LMAU requiring more frequent adjustment of the head and neck to achieve a proper position. Fiberoptic scores were excellent with both devices. Respiratory variables were similar with the exception that the plateau pressure and mean peak pressures were significantly lower with CobraPLA. There was a low rate of blood mucosal staining of the devices. No patient in either group reported a sore throat.

CONCLUSIONS

Both devices appear to be safe and effective in establishing an adequate airway in healthy children undergoing surgery of short duration with PCV.

Comparison of LMA Unique, Ambu laryngeal mask and Soft Seal laryngeal mask during routine surgical procedures

BACKGROUND AND OBJECTIVE

This study was performed to compare three disposable airway devices, the LMA Unique (LMA-U), the Ambu laryngeal mask (Ambu LM) and the Soft Seal laryngeal mask (Soft Seal LM) for elective general anaesthesia during controlled ventilation in non-paralysed patients.

METHODS

One hundred and twenty ASA I-III patients scheduled for routine minor obstetric surgery were randomly allocated to the LMA-U (n = 40), Ambu LM (n = 40) or Soft Seal LM (n = 40) groups, respectively. Patients were comparable with respect to weight and airway characteristics. A size 4 LMA was used in all patients and inserted by a single experienced anaesthesiologist. Oxygenation, overall success rate, insertion time, cuff pressure and resulting airway leak pressure were determined as well as a subjective assessment of handling and the incidence of sore throat, dysphagia and hoarseness.

RESULTS

Time of insertion was shortest with the Ambu LM, while failure rates were comparable with the LMA-U, the Ambu LM and the Soft Seal LM (median 19 s; range 8-57 s; success rate 100% vs. 14; 8-35; 97% vs. 20; 12-46; 95%). Insertion was judged 'excellent' in 75% of patients in the LMA-U group, in 70% of patients in Ambu LM group and in 65% of patients in the Soft Seal LM group. There was no difference between devices with respect to postoperative airway morbidity at 6 h or 24 h following surgery.

CONCLUSIONS

All three disposable devices were clinically suitable with respect to insertion times, success rates, oxygenation, airway and leak pressures, as well as to subjective handling and postoperative airway morbidity.

A comparison of the oropharyngeal leak pressure between the reusable Classic laryngeal mask airway and the single-use Soft Seal laryngeal mask airway

We tested the oropharyngeal leak pressure with the reusable laryngeal mask airway and the single-use Soft Seal laryngeal mask airway. These two types of laryngeal mask airway (LMA) have a similar design but the reusable LMA cuff is made from silicone whereas the Soft Seal LMA cuff is polyvinylchloride. Thirty-five healthy subjects were anaesthetized and paralyzed and the two types of Soft Seal LMA were compared in a blinded randomized cross-over trial. The oropharyngeal leak pressure was significantly higher with the Soft Seal than the reuable (21 +/- 7.6 and 16 +/- 6.7 cm H2O respectively, P = 0.002). However, in four subjects the oropharyngeal leak pressure was higher with the reusable by > 4 cm H2O. We concluded that the reusable LMA may provide a better seal in some individuals but that, on average, the Soft Seal provides a higher oropharyngeal leak pressure than the reusable LMA.

The anatomical position of three extraglottic airway devices in patients with clear airways

We tested the hypothesis that, in patients with clear airways, the anatomical position of three single-use extraglottic airway devices is similar. The airways studied were: the laryngeal mask airway unique (LMA-U), the Softseal laryngeal mask airway (SS-LM) and the Cobra perilaryngeal airway (Cobra-PLA). Three hundred spontaneously breathing patients were randomly allocated to have their airway managed using one of these three supraglottic airway devices. A rigid endoscope was passed down the airway tube and the following anatomical assessments were made: position of the epiglottis; position of the glottis; and position of the cuff. The epiglottis was more frequently visible with the LMA-U than with the SS-LM (76 vs 57%, p = 0.006) and with the LMA-U than with the Cobra-PLA (76 vs 46%, p < 0.0001). The epiglottis was in contact with the mask aperture bars in 25% of patients, and in 34% of these, the epiglottis was seen to be herniated through the aperture bars. Herniation of the epiglottis through the mask aperture bars occurred more frequently with the Cobra-PLA than the LMA-U (8 vs 3%, p = 0.008). The vocal cords and arytenoids were more frequently visible with the LMA-U and SS-LM than with the Cobra-PLA (both p < 0.006). Herniation of the arytenoids through the mask aperture bars was more frequently seen with the Cobra-PLA than with the LMA-U (8 vs 0%, p = 0.004). The position of the cuff was optimal for the LMA-U and SS-LM in 90% and 93% of patients, respectively. The cuff was more frequently in the midline with the LMA-U than with the SS-LM (p = 0.002). We conclude that the anatomical position of the LMA-U and SS-LMA is superior to that of the Cobra-PLA in patients with clear airways. The mask aperture bars probably have no anatomical utility and predispose to herniation of the pharyngeal structures.

New airways for resuscitation?

Over the last 15 years supraglottic airway devices (SADs), most notably the classic laryngeal mask airway (LMA) have revolutionised airway management in anaesthesia. In contrast for resuscitation, both in and outside hospital, facemask ventilation and tracheal intubation remain the mainstays of airway management. However there is evidence that both these techniques have complications and are often poorly performed by inexperienced personnel. Tracheal intubation also has the potential to cause serious harm or death through unrecognised oesophageal intubation. SADs may have a role in airway management for resuscitation as first responder devices, rescue devices or for use during patient extraction. In particular they may be beneficial as the level of skill required to use the device safely may be less than for the tracheal tube. Concerns have been expressed over the ability to ventilate the lungs successfully and also the risk of aspiration with SADs. The only SADs recommended by ILCOR in its current guidance are the classic LMA and combitube. Several SADs have recently been introduced with claims that ventilation and airway protection is improved. This pragmatic review examines recent developments in SAD technology and the relevance of this to the potential for using SADs during resuscitation. In addition to examining research directly related to resuscitation both on bench models and in patients the review also examines evidence from anaesthetic practice. SADS discussed include the classic, intubating and Proseal LMAs, the combitube, the laryngeal tube, laryngeal tube sonda mark I and II and single use laryngeal masks.

A randomised comparison of the Portex Softseal laryngeal mask airway with the LMA-Unique during anaesthesia

We have compared the performance of the single use laryngeal airway devices Softseal and LMA-Unique in a randomised comparative trial in anaesthetised healthy patients who did not receive neuromuscular blockade. Primary outcome was success of airway placement. Secondary outcomes included manipulations and complications during use, ease of insertion, airway and fibreoptic assessment of airway positioning, and complications postoperatively. We planned to study 300 patients but interim analysis demonstrated the study should be stopped after 100 patients. During insertion the Softseal required more attempts for successful insertion (p = 0.041), more manipulations (p < 0.0001) and caused more complications (p = 0.048). Failure of placement occurred in five cases with the Softseal and none with the LMA-Unique (p = n/s). Two Softseal needed to be removed during maintenance because of airway obstruction, giving an overall failure rate of seven (p = 0.013). Serial tests of positioning favoured the LMA-Unique (p = 0.012). Ventilation was more successful in the LMA-Unique group but the difference was not significant (p = 0.051). Seal pressure was higher with the Softseal (26.5 vs. 20.5 cmH(2)O, p = 0.005). Fibreoptic view via the devices was not statistically significantly different. During maintenance of anaesthesia more complications arose with the Softseal (p = 0.03). Anaesthetist ratings of ease of insertion and overall usefulness favoured the LMA-Unique (p < 0.0001 and p = 0.024, respectively). After anaesthesia, sore throat occurred more frequently and was more severe in those patients anaesthetised with a Softseal both in recovery (p = 0.015) and at 24 h (p = 0.012). We conclude that the Softseal performs less well and causes more complications than the LMA-Unique.

Randomised, crossover comparison of the single-use SoftSeal?and the LMA Unique?laryngeal mask airways

We performed a randomised, crossover, single-blind trial among 168 patients, to compare the single-use SoftSeal and LMA Unique laryngeal mask airways in spontaneously breathing adults. Size-3 and -4 laryngeal mask airways, inserted by experienced anaesthetists, performed equivalently for successful first-time placement (148 (91%) vs 155 (96%) for the SoftSeal and LMA Unique, respectively). The SoftSeal was more often rated as difficult to insert (27 (17%) vs 4 (3%); p < 0.001) and was more likely to show evidence of mucosal trauma after the first insertion (14 (10%) vs 5 (4%); OR 1.3 (95% CI 1.3-11.3); p < 0.05). The fibreoptic view of the larynx was better through the SoftSeal (vocal cords not visible in 27 (17%) vs 44 (27%); p < 0.05) and it more frequently provided a ventilation seal at 20 cmH(2)O (93 (59%) vs 62 (39%); OR 2.15 (CI 1.44-3.21); p < 0.001). In contrast to the LMA Unique(trade mark), its cuff pressure did not increase during nitrous oxide anaesthesia (median (IQR [range]) decrease 3 (- 20-23 [-40-94]) cmH(2)O vs increase of 16 (-2-39 [-54-112]) cmH(2)O; p < 0.01). Both devices were equivalent for the success of first-time insertion and performed satisfactorily clinically. There were some performance differences, but either appears suitable for airway management in spontaneously breathing patients.