A Proposed Classification and Scoring System for Supraglottic Sealing Airways: A Brief Review

Comparison of clinical performance of Baska mask and Ambu AuraGain in patients undergoing surgery: A single-blinded, randomised comparative trial

Background and Aims

The Baska mask (BM) and the Ambu AuraGain (AAG) have shown promising results in recent trials but have not been compared. Therefore, we aimed to compare the clinical performance of the BM and the AAG for airway management of adult patients.

Methods

In this randomised comparative study, patients aged 18-60 years and with an expected surgical duration of less than 2 h were enroled. Patients were randomly allocated to AAG (Group A, n = 37) and BM (Group B, n = 37) for airway management. After induction of anaesthesia, an allocated supraglottic airway device (SAD) was inserted. Oropharyngeal leak pressure (OLP), time taken to insert SAD, number of insertion attempts, leak fraction (LF), first-attempt success rate, overall success rate, ease of insertion, fiberoptic view of the glottis, and complications were compared. The data were analysed using Student's t-test, Mann-Whitney U test, and Fisher's exact tests.

Results

Baseline and demographic characteristics were comparable. OLP (31.32 ± 2.59 versus 27.54 ± 1.32 cmH2O) was higher (P < 0.001), and LF (6.19% ± 1.20% versus 7.24% ± 1.72%) was lower (P = 0.003) in the BM group. First-attempt and overall success rate, time taken to insert, number of insertion attempts, ease of insertion, and fibreoptic view of glottis through the SADs were statistically similar between groups. However, the incidence of sore throat (P = 0.007) and cough (P = 0.028) was higher with AAG.

Conclusion

Clinical performance of BM was better than AAG as the former had higher OLP, lower LF and complications.

Laryngeal Masks in Neonatal Resuscitation-A Narrative Review of Updates 2022

Positive pressure ventilation (PPV) is crucial to neonatal cardiopulmonary resuscitation because respiratory failure precedes cardiac failure in newborns affected by perinatal asphyxia. Prolonged ineffective PPV could lead to a need for advanced resuscitation such as intubation, chest compression, and epinephrine. Every 30 s delay in initiation of PPV increased the risk of death or morbidity by 16%. The most effective interface for providing PPV in the early phases of resuscitation is still unclear. Laryngeal masks (LMs) are supraglottic airway devices that provide less invasive and relatively stable airway access without the need for laryngoscopy which have been studied as an alternative to face masks and endotracheal tubes in the initial stages of neonatal resuscitation. A meta-analysis found that LM is a safe and more effective alternative to face mask ventilation in neonatal resuscitation. LM is recommended as an alternative secondary airway device for the resuscitation of infants > 34 weeks by the International Liaison Committee on Resuscitation. It is adopted by various national neonatal resuscitation guidelines across the globe. Recent good-quality randomized trials have enhanced our understanding of the utility of laryngeal masks in low-resource settings. Nevertheless, LM is underutilized due to its variable availability in delivery rooms, providers’ limited experience, insufficient training, preference for endotracheal tube, and lack of awareness.

Clinical Performance Comparison of LMA Protector™ Cuff Pilot™ and LMA Supreme™ When Used in Anesthetized, Non-paralyzed Patients

Introduction

The advancement of supraglottic airways (SGAs) has eased airway management, especially for anesthetists. There were functional improvements implemented to the newer SGA. We aim to assess the clinical performance of laryngeal mask airway (LMA) Protector™ Cuff Pilot™ (Teleflex Inc., Wayne, Pennsylvania, USA) against LMA Supreme™ (Teleflex Inc., Wayne, Pennsylvania, USA), in terms of oropharyngeal leak pressure (OLP), successful insertion attempts, mean insertion time, ease of gastric tube insertion, laryngeal view, and incidence of sore throat among anesthetized, non-paralyzed patients undergoing general anesthesia.

Methods

In this prospective single-blinded study, 60 patients were randomized to use either LMA Protector™ Cuff Pilot™ or LMA Supreme™. Both groups received standard monitoring and induction regimes. Post-insertion, a bronchoscope was used to verify its position. A gastric tube was inserted and OLP was measured. Patients were assessed during the post-operative period for sore throats.

Results

LMA Protector™ Cuff Pilot™ was comparable to LMA Supreme™ in terms of mean OLP (30.72±8.60 vs 27.23±8.09 cmH₂O, P = 0.114), first successful attempt (P = 0.312), mean insertion time (27.72±9.45 vs 24.37±6.46 seconds, P = 0.116), and grade 1 laryngeal view (51.7% vs 36.7%, P = 0.244). At first attempt, LMA Protector™ Cuff Pilot™ had a lower success rate of gastric tube insertion than LMA Supreme™ (55.17% vs 96.67%, P <0.001). The incidence of the blood-stained device and sore throat post-operatively were comparable between the two groups.

Conclusion

LMA Protector™ Cuff Pilot™ was comparable to LMA Supreme™ in terms of overall clinical performance, except for the first successful gastric tube insertion. Improvements should be made to the gastric channel for easier gastric tube insertion in the LMA Protector™ Cuff Pilot™.

Evaluation of the insertion parameters and complications of the i-gel Plus airway device for maintaining patent airway during planned procedures under general anaesthesia: a protocol for a prospective multicentre cohort study

INTRODUCTION

Supraglottic airway devices represent a less invasive method of airway management than tracheal intubation during general anaesthesia. Their continued development is focused mainly on improvements in the insertion success rate and minimalisation of perioperative and postoperative complications. The i-gel Plus is a novel, anatomically preshaped supraglottic airway device which achieves a perilaryngeal seal due to a non-inflatable cuff made of a soft thermoplastic elastomer. The purpose of this cohort study is to assess the success rate of the i-gel Plus use during elective procedures under general anaesthesia, its intraoperative performance, and the degree of postoperative complications.

METHODS AND ANALYSIS

This is a multicentre, prospective, interventional cohort study. The enrolment will take place in seven centres in four European countries. We plan to enrol 2000 adult patients in total, who are scheduled for elective surgery under general anaesthesia, and with an indication for use of a supraglottic airway device for management of their airway. The study is projected to run over a period of 18 months. The primary outcome of the study is the total success rate of the i-gel Plus insertion in terms of successful ventilation and oxygenation through the device. Secondary outcomes include perioperative parameters, such as insertion time, seal/leak pressures, number of insertion attempts and postoperative adverse events and complications. Postoperative follow-up will be performed at 1 hour, 24 hours in all patients, and for selected patients at 3 and 6 months.

ETHICS AND DISSEMINATION

The cohort study has received the following ethical approvals: General University Hospital Prague, University Hospital Olomouc, University Military Hospital Prague, University Hospital Barcelona, University Hospital Lodz, Antrim Area Hospital, Craigavon Area Hospital, Office for Research Ethics Committees Northern Ireland. The results will be published in peer-reviewed journals and presented at relevant anaesthesia conferences.

TRIAL REGISTRATION NUMBER

ISRCTN86233693;Pre-results.

Time to consider supraglottic airway device oropharyngeal leak pressure measurement more objectively

Oropharyngeal leak pressure (OLP) is considered a measure of successful placement, adequate performance and is a useful comparator between supraglottic airway devices (SADs). OLP measurement is based on the premise that the SAD is sited properly in the hypopharynx after blind placements, but the evidence suggests otherwise. Several limitations and controversies surround OLP. This editorial addresses the uses and pitfalls of OLP, the rationale for and methods of ascertaining OLP, the pros and cons of OLP measurement and newer modalities to improve its accuracy.

Evaluation of performance of Streamlined Liner of the Pharynx Airway™, Laryngeal Mask Airway-ProSeal and endotracheal tube in prone position: A prospective, randomised study

Background and Aims:

Airway used in prone position should be efficacious and safe. The Streamlined Liner of the Pharynx Airway (SLIPA™) and Laryngeal Mask Airway-ProSeal (PLMA) provide better airway seal and protection against aspiration. We planned to evaluate the performance of SLIPA™, PLMA and endotracheal tube (ETT) in prone position.

Methods:

114 adult patients undergoing elective surgery in prone position under general anaesthesia were randomised into Group-T (ETT), Group-S (SLIPA™) and Group-P (PLMA). Airways were inserted in supine position and patients turned prone subsequently. Airway characteristics, ventilatory parameters and complications were noted. One-way analysis of variance, Mann–Whitney U-test and Chi-square or Fisher's exact test were used.

Results:

Tidal volumes, peak airway pressure and compliance were comparable at all times. Leak pressure was significantly higher (P < 0.001) in Group-T (mean leak pressure = 40 cmH₂O) when compared to Group-S and Group-P at all the times of recording, and there was no significant difference between Group-S and Group-P. The number of patients requiring airway/neck manipulation in prone position was significantly higher (P < 0.001) in Group-S (19 [55.9%]) when the three groups were compared (none in Group-T) and in comparison with Group-P (5 [14.7%], P < 0.001). On airway removal, the incidence of complications and airway reaction was significantly higher in Group-T. Group-S had a significantly higher incidence of dysphagia at 2 h postoperatively.

Conclusion:

ETT was most efficacious. SLIPA™ and PLMA were efficacious, safe and less stimulating to the airway during removal. More patients required SLIPA™ airway/neck manipulation.

Ambu AuraOnce versus i-gel laryngeal mask airway in infants and children undergoing surgical procedures. A randomized controlled trial

Objectives:

To compare the efficacy and performance of the pediatric Ambu AuraOnce (Ambu AO) mask (Ambu, Copenhagen, Denmark) and i-gel mask (Intersurgical Ltd., Wokingham, United Kingdom).

Methods:

From May 2015 to September 2016, 112 patients, 0-14 years old, underwent elective surgery at a tertiary university hospital (Riyadh, Saudi Arabia). They were randomly assigned to the Ambu AO or i-gel group. Three groups underwent a subgroup analysis: ≤5 kg (group 1), 5.1–10.0 kg (group 2), and >10 kg (group 3).

Results:

The oropharyngeal leak pressure was significantly higher for the i-gel (25.4±4.1 cm H₂O) than for the Ambu AO (22.5±3.9 cm H₂O, p<0.001). The Ambu AO had a slightly higher ease of insertion compared to the i-gel (100% versus 94%, p=0.08) and required less manipulation (2% versus 11%, p=0.07).The Ambu AO and i-gel showed non-significant differences in performance between weight groups. There were statistically significant differences for higher leak pressure in group 2 (p=0.01) and group 3 (p=0.002) in favor of the i-gel, and for less manipulation in the Ambu AO in group 1 (p=0.04). Fiberoptic viewing was superior in group 2 for the i-gel (p=0.03) and in group 3 for the Ambu AO (p=0.02).

Conclusion:

Both devices demonstrated equally good performance with low morbidity. The Ambu AO had a statistical tendency towards easier insertion and less manipulation. Confirming this finding will require large scale trials.

Comparison Between the Cobra Perilaryngeal Airway and Laryngeal Mask Airways Under General Anesthesia: A Systematic Review and Meta-analysis

The complication rate and efficacy of the Cobra Perilaryngeal Airway (CobraPLA) and laryngeal mask airways (LMAs®) have been evaluated in the published literature, but the conclusions have been inconsistent. The aim of this systematic review and meta-analysis was thus to assess the performance of the CobraPLA and LMAs under general anesthesia. We searched PubMed, Embase, and the Cochrane Library for randomized controlled trials comparing the CobraPLA with LMAs under general anesthesia. The LMAs used for comparison were the classic LMA (CLMA) and the unique LMA (ULMA). The random effect model was used if heterogeneity was observed, otherwise the fixed effect model was used. Seventeen randomized controlled trials were included; number of studies analyzed for each result are different and were up to 10. The current result suggests that no significant difference between the devices in the insertion success rate at the first attempt. The success rate of first insertion of the CobraPLA was not different from the rates for the CLMA and the ULMA (relative risk: 0.95, 95% confidence interval [CI], 0.91-1.00). CobraPLA insertion was not different from CLMA and ULMA insertion. The CobraPLA provided an oropharyngeal leak pressure higher than that provided by the CLMA (weight mean difference: 3.90, 95% CI, [1.59-6.21] cmH2O) and ULMA (weight mean difference: 6.57, 95% CI, [4.30-8.84] cmH2O). We also found a higher likelihood of blood staining in the airway with the CobraPLA than with the CLMA. In our research, the principal finding of our meta-analysis is that the success rate of first insertion of the CobraPLA was not different from the rate for each of the CLMA and the ULMA, which featured a short learning curve implying its ease of insertion. There was also no significant difference in the incidence of the best view (with a score of 4) obtained with the CobraPLA compared with the other 2 devices. The CobraPLA does seem to be superior to the CLMA and ULMA in providing a higher oropharyngeal leak pressure. The data were insufficient to establish differences in airway adverse events between the groups except for blood staining in the devices, although mucosal trauma occurred more frequently with the Cobra PLA device than with the CLMA and the ULMA.

Extraglottic airway devices: technology update

Extraglottic airway devices (EADs) have revolutionized the field of airway management. The invention of the laryngeal mask airway was a game changer, and since then, there have been several innovations to improve the EADs in design, functionality, safety and construction material. These have ranged from changes in the shape of the mask, number of cuffs and material used, like rubber, polyvinylchloride and latex. Phthalates, which were added to the construction material in order to increase device flexibility, were later omitted when this chemical was found to have serious adverse reproductive outcomes. The various designs brought out by numerous companies manufacturing EADs resulted in the addition of several devices to the airway market. These airway devices were put to use, many of them with inadequate or no evidence base regarding their efficacy and safety. To reduce the possibility of compromising the safety of the patient, the Difficult Airway Society (DAS) formed the Airway Device Evaluation Project Team (ADEPT) to strengthen the evidence base for airway equipment and vet the new extraglottic devices. A preuse careful analysis of the design and structure may help in better understanding of the functionality of a particular device. In the meantime, the search for the ideal EAD continues.

Comparison of the Disposable Streamlined Liner of the Pharynx Airway and the Disposable I-gel in Anaesthetized, Paralyzed Adults: A Randomized Prospective Study

Introduction. This study compared streamlined liner of the pharynx airway (SLIPA) and I-gel noninflatable, single-use, supraglottic airway device (SAD) performance in anesthetized, paralyzed adults. Methods. Eighty adults (ASA physical statuses I–III) who were undergoing elective procedures under general anesthesia with an SAD were enrolled in this prospective, randomized, single-blind study. Subjects were randomly and evenly assigned to the SLIPA or I-gel group for intraoperative airway management. Ease and number of insertions, insertion time, oropharyngeal sealing pressure, hemodynamic response, oxygen saturation (SpO₂), end-tidal CO₂ (EtCO₂), and peri- and postoperative complications were examined. Results. The SLIPA and I-gel devices were successfully inserted in 100% and 95% of subjects, respectively. In two I-gel subjects (5%), ventilation was not possible after two attempts, but a size 55 SLIPA was successfully inserted in both cases. Forty-two and 38 patients were ultimately included in the SLIPA and I-gel groups, respectively. Insertion time was significantly shorter with the SLIPA (11.19 ± 3.03 s) than with the I-gel (15.05 ± 6.37 s, P = 0.003). Oropharyngeal sealing pressure was significantly higher in SLIPA (28.76 ± 3.11 cmH₂O) than in I-gel (25.9 ± 3.65 cmH₂O) subjects (P = 0.001). Blood staining occurred more frequently in SLIPA (n = 8, 19.0%) than in I-gel (n = 5, 13.2%) patients (P < 0.01). Heart rate, mean arterial blood pressure, SpO₂, and EtCO₂ were not significantly different between groups. Conclusion. Although blood staining incidence was higher, SLIPA insertion was easier and faster than I-gel insertion. The SLIPA provided better airway sealing pressure. Both devices had similar mechanical ventilation and oxygenation characteristics and comparable hemodynamic stability. Both noninflatable SADs are useful, but SLIPA rapid insertion and good airway sealing make it an effective alternative to the I-gel.

Complications Associated with the Use of Supraglottic Airway Devices in Perioperative Medicine

Supraglottic airway devices are routinely used for airway maintenance in elective surgical procedures where aspiration is not a significant risk and also as rescue devices in difficult airway management. Some devices now have features mitigating risk of aspiration, such as drain tubes or compartments to manage regurgitated content. Despite this, the use of these device may be associated with various complications including aspiration. This review highlights the types and incidence of these complications. They include regurgitation and aspiration of gastric contents, compression of vascular structures, trauma, and nerve injury. The incidence of such complications is quite low, but as some carry with them a significant degree of morbidity the need to follow manufacturers' advice is underlined. The incidence of gastric content aspiration associated with the devices is estimated to be as low as 0.02% with perioperative regurgitation being significantly higher but underreported. Other serious, but extremely rare, complications include pharyngeal rupture, pneumomediastinum, mediastinitis, or arytenoid dislocation. Mild short-lasting adverse effects of the devices have significantly higher incidence than serious complications and involve postoperative sore throat, dysphagia, pain on swallowing, or hoarseness. Devices may have deleterious effect on cervical mucosa or vasculature depending on their cuff volume and pressure.

Pre-warming the Streamlined Liner of the Pharynx Airway (SLIPA) improves fitting to the laryngeal structure: a randomized, double-blind study

Background

The Streamlined Liner of the Pharynx Airway (SLIPA), a type of supraglottic airway, has a non-inflatable cuff that softens at body temperature to fit the laryngeal structure. We investigated whether pre-warming of SLIPA to body temperature may improve insertion parameters.

Methods

Ninety adult patients were assigned equally randomized to either Group W or Group R. Anesthesia was induced using propofol, fentanyl, and rocuronium. In Group W, the SLIPA was warmed to 37 ° C before insertion, whereas in Group R, it was inserted at room temperature. The insertion time, oropharyngeal leak pressure, postoperative throat pain, blood staining, regurgitation, number of attempts at insertion, and difficulty of insertion were compared between the two groups.

Results

The insertion time was shorter in Group W than in Group R (3.60 [3.15–4.06] s vs. 6.00 [4.45–7.50] s; P < 0.001). Oropharyngeal leak pressure from the time of insertion until 3 min after insertion was significantly higher in Group W than in Group R (P < 0.05). Postoperative throat pain, measured using the visual analog scale, was lower in Group W than in Group R (0.00 [0.00–2.50] vs. 2.00 [0.00–4.50]; P = 0.006). The difficulty of insertion was lower in Group W than in Group R (P < 0.004). There were no significant differences in terms of blood staining, regurgitation, and number of attempts.

Conclusions

Pre-warming the SLIPA to body temperature has significant benefits compared to maintaining the device at room temperature. Specifically, insertion was easier, both insertion and fitting to the laryngeal structure could be performed more quickly, and the incidence of sore throat was reduced.

Trial registration

Clinical Research Information Identifier NCT01209000

Laryngeal mask airway without muscle relaxant in femoral head replacement in elderly patients

The number of elderly patients undergoing femoral head replacement surgeries is on the increase. These patients often suffer from comorbidity such as cardiovascular and cerebrovascular complications, which limits the ability of medical teams to employ anesthesia. Thus, alternative methods are required. The aim of this study was to examine the advantage of laryngeal mask airway (LMA) in the absence of muscle relaxant in elderly patients undergoing femoral head replacement operations. Fifty patients (27 males and 23 females) undergoing femoral head replacements were selected for the study between March 2013 and May 2014. The mean value for the age in this group was 74.6±12.5 years. The patients were randomly distributed into two groups of 25. One group was designated as the treatment group and the second group as the control group. For the treatment group, LMA without muscle relaxant was used, and the control group received routine anesthesia. Variations in heart rate (HR), mean arterial pressure (MAP) and oxygen saturation (SPO₂) in the two groups were monitored at different times. Clinical efficacy and muscle relaxation effects were also analyzed. For the treatment group, the HR, MAP and SPO₂ measurements did not reveal any significant variation while these values in the control group demonstrated important dissimilarities. Time to recovery, time to extubation and incidence of throat pain in the treatment group were all markedly decreased as compared to those in control group. The operation time in the treatment group was not significantly different to that of control group. The satisfaction of the muscle relaxation effect in the treatment group was significantly higher than that in the control group while the incidence of adverse reactions was not considerably different. In conclusion, the use of LMA without using muscle relaxant in femoral head replacement surgeries performed on elderly patients showed to be effective and safe.

A pilot evaluation of the 3gLM-R - A new supraglottic airway device

INTRODUCTION

Supraglottic airway devices are designed for airway management during anaesthesia. The 3gLM is a novel device with a non-inflatable soft cuff and separate channels for gas delivery and drainage of gastric content.

MATERIAL AND METHODS

This prospective observational study of the 3gLM, version R, size 4 in 40 adult patients scheduled for elective surgery, evaluated the insertion success rate at the 1st attempt as the primary outcome. Secondary aims included insertion parameters, such as total success rate, insertion time, oropharyngeal seal pressures, postoperative complications and a comparison between males and females.

RESULTS

First attempt insertion success rate was 80% (70% in males, 90% in female patients, p=0.24), while total insertion success rate was 92.5% (85% in males, 100% in females, p=0.23). The oropharyngeal seal pressures were 27cmH2O, higher in females (29.4cmH2O) than in males (24.2cmH2O) - p=0.002. Postoperative complications were only temporary and included sore throat (24.3%), hoarseness (10.8%), pain on swallowing (10.8%) and minor tongue haematoma (2.5%). There was no difference in the incidence of postoperative complications between the genders apart from hoarseness. No aspiration of gastric contents or other long-term complications occurred in this cohort.

CONCLUSIONS

The 3gLM exhibited oropharyngeal seal pressures adequate for the controlled ventilation in most patients. Size 4 of the device showed higher pressures in females than in men.

Airway management evolution - in a search for an ideal extraglottic airway device

Extraglottic airway devices (EADs) are commonly used equipment for airway maintenance during elective procedures under general anaesthesia. They may be used also in other indications such as conduit for tracheal intubation or rescue airway device in prehospital medicine. Current classifications of the EADs lack systematic approach and therefore classification according to the sealing sites and sealing mechanisms is suggested in this review article. Modern EADs are disposable, latex-free devices made of plastic materials most commonly from polyvinylchloride (PVC). The bowl of uncuffed sealers is manufactured from different materials such as thermoplastic elastomers or ethylene-vinyl-acetate co-polymer. EADs create various physical forces exerted on the adjacent tissues which may contribute to different sealing characteristic of particular device or to variable incidence of postoperative complications. Desired features of an ideal EAD involve easy insertion, high insertion success rate even by inexperienced users, protection against aspiration of gastric contents and low incidence of postoperative complications such as sore throat, hoarseness, cough or swallowing difficulties.

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.

Are new supraglottic airway devices, tracheal tubes and airway viewing devices cost-effective?

Over the past two decades, a plethora of new airway devices has become available to the pediatric anesthetist. While all have the laudable intention of improving patient care and some have proven clinical benefits, these devices are often costly and at times claims of an advantage over current equipment and techniques are marginal. Supraglottic airway devices are used in the majority of pediatric anesthetics delivered in the U.K., and airway-viewing devices provide an alternative for routine intubation as well as an option in the management of the difficult airway. Yet hidden beneath the convenience of the former and the technology of the latter, the impact on basic airway skills with a facemask and the lack of opportunities to fine-tune the core skill of intubation represent an unrecognised and unquantifiable cost. A judgement on this value must be factored into the absolute purchase cost and any potential benefits to the quality of patient care, thus blurring any judgement on cost-effectiveness that we might have. An overall value on cost-effectiveness though not in strict monetary terms can then be ascribed. In this review, we evaluate the role of these devices in the care of the pediatric patient and attempt to balance the advantages they offer against the cost they incur, both financial and environmental, and in any quality improvement they might offer in clinical care.

Extraglottic airway devices: A review

Extraglottic airway devices (EAD) have become an integral part of anesthetic care since their introduction into clinical practice 25 years ago and have been used safely hundreds of millions of times, worldwide. They are an important first option for difficult ventilation during both in-hospital and out-of-hospital difficult airway management and can be utilized as a conduit for tracheal intubation either blindly or assisted by another technology (fiberoptic endoscopy, lightwand). Thus, the EAD may be the most versatile single airway technique in the airway management toolbox. However, despite their utility, knowledge regarding specific devices and the supporting data for their use is of paramount importance to patient's safety. In this review, number of commercially available EADs are discussed and the reported benefits and potential pitfalls are highlighted.

Comparison of the i-gel™ and the Laryngeal Mask Airway Classic™ in terms of clinical performance

PURPOSE

The i-gel™ is one of the second generation supraglottic airway devices. Our study was designed to compare the i-gel and the Laryngeal Mask Airway Classic™ with respect to the clinical performance.

METHODS

We compared the performance of the i-gel with that of the Laryngeal Mask Airway Classic in 120 patients undergoing urologic surgery during general anesthesia without muscle relaxant with respect to the number of attempts for successful insertion, insertion time, peak airway pressure, incidence of regurgitation, fiberoptic glottic view and postoperative complications. Second generation supraglottic airway devices were inserted by the same anesthesiologist, experienced in use of both devices (>200 uses and first time failure rate <5%). Methylene blue method was used to detect gastric regurgitation.

RESULTS

There was no statistical difference between the two groups regarding the success of insertion of second generation supraglottic airway device (p=0.951). The laryngeal mask insertion time for the i-gel group was significantly shorter than that for the Laryngeal Mask Airway Classic group (11.6±2.4s versus 13.1±1.8s [p=0.001]). The fiberoptic glottic view scores for the i-gel group was significantly better than that for the ones for the Laryngeal Mask Airway Classic group (p=0.001). On fiberoptic view, there was no sign of methylene blue dye at any time point in either group. In addition, there was no difference between the groups in patient response regarding the presence of a sore throat when questioned 24h after the procedure (p=0.752).

CONCLUSION

Both devices had good performance with low postoperative complications and without occurrence of regurgitation. The i-gel provided a shorter insertion time and a better fiberoptic view than the Laryngeal Mask Airway Classic.

ProSeal™ laryngeal mask airway cuff pressure changes with and without use of nitrous oxide during laparoscopic surgery

Background:

The ProSeal™ laryngeal mask (PLMA) is increasingly being used as an airway device for laparoscopic surgery. Its silicone cuff allows diffusion of nitrous oxide, carbon dioxide and other gases with resultant rise in its intracuff pressure during anesthesia. The present study was designed to investigate the intracuff pressure changes during anesthesia with and without nitrous oxide in patients undergoing laparoscopic surgery lasting up to two hours.

Materials and Methods:

One hundred patients, American Society of Anesthesiologists physical status 2 and 3, undergoing general anesthesia with muscle paralysis, were randomized into two groups of 50 patients each to receive an anesthetic gas mixture containing either oxygen and nitrous oxide (group N) or oxygen and air (group A). Following insertion of an appropriate size PLMA, its cuff was inflated with air to an intracuff pressure of 45 mm Hg. The cuff pressure was measured every 10 minutes for the entire course of anesthesia. The position of the device was also assessed fiberoptically and postoperative airway complications were recorded.

Results:

The maximum intracuff pressure recorded in group N was 103 ± 4.7 mm Hg vs. 45.5 ± 1.5 mm Hg in group A. The percentage rise in cuff pressure every 10 minutes was also highly significant (P < 0.001) being maximum in first 10 min in group N. The incidence of postoperative airway complications was comparable between the two groups.

Conclusion:

The results of this study demonstrate that the intracuff pressure of the PLMA increases progressively over time when the breathing gas mixture contains nitrous oxide.

A novel method for SLIPA™ size selection, for adult patients, on the basis of chamber length

PURPOSE

Nowadays the size of the streamlined liner of the pharynx airway (SLIPA™) is selected by matching the width of the thyroid cartilage of the patient to the widest dimension of the SLIPA™. The objective of this work was to improve the method of selection by matching the distance between the otobasion inferius and the most inferior margin of the cricoid cartilage (O-C) to the length of the SLIPA™ chamber.

METHODS

100 patients (ASAI-II) scheduled to undergo operations under general anesthesia were randomly divided into two groups, group A (size selected by matching O-C with SLIPA™ chamber length, n = 50) and group B (size selected by matching the width of the thyroid cartilage with the widest dimension of the SLIPA™, n = 50). We measured the distance between the nasopharynx and the interarytenoid fold (N-I) and investigated the correlation between O-C and N-I at the neutral head position. Number of attempts, insertion time, blood on the device, leakage, and the need to change sizes were assessed.

RESULTS

A positive correlation (r = 0.68, p < 0.05) was detected between N-I and O-C. Leakage was observed in 6 % (n = 3) of group A patients and in 20 % (n = 10) of group B patients (p < 0.05).

CONCLUSION

Compared with the classic size-selection method, matching the width of the thyroid cartilage with that of the SLIPA™, the size-selection method of matching SLIPA™ chamber length to O-C for adult patients is more accurate.

Supraglottic airway devices in children

Modern anaesthesia practice in children was made possible by the invention of the endotracheal tube (ET), which made lengthy and complex surgical procedures feasible without the disastrous complications of airway obstruction, aspiration of gastric contents or asphyxia. For decades, endotracheal intubation or bag-and-mask ventilation were the mainstays of airway management. In 1983, this changed with the invention of the laryngeal mask airway (LMA), the first supraglottic airway device that blended features of the facemask with those of the ET, providing ease of placement and hands-free maintenance along with a relatively secure airway. The invention and development of the LMA by Dr. Archie Brain has had a significant impact on the practice of anaesthesia, management of the difficult airway and cardiopulmonary resuscitation in children and neonates. This review article will be a brief about the clinical applications of supraglottic airways in children.

Effectiveness of the Streamlined Liner of the Pharynx Airway (SLIPA™) in Allowing Positive Pressure Ventilation during Gynaecological Laparoscopic Surgery

The aim of this study was to assess whether the Streamlined Liner of the Pharynx Airway (SLIPA™) performed as well as an endotracheal tube for positive pressure ventilation in gynaecological laparoscopic surgery in the Trendelenburg position. Forty patients (American Society of Anesthesiologists physical status I to III) were randomly divided into two groups: SLIPA (n=20) or endotracheal tube group (n=20). Lung mechanics and severity of postoperative sore throat were assessed in both groups. In the SLIPA group, the oropharyngeal leak pressure was also measured.

There were no significant differences between groups in the lung mechanics. In the SLIPA group, oropharyngeal leak pressure and peak inspiratory pressure increased significantly after gas insufflation compared to 10 minutes after patient positioning in the lithotomy position (P <0.05). The difference between oropharyngeal leak pressure and peak inspiratory pressure (approximately 10 cmH2O throughout the procedure) remained suitable for airway maintenance. The incidence of sore throat was similar in both groups but the severity was less in the SLIPA group 24 hours after surgery (P <0.05). There were no other complications such as regurgitation noted in either group. In the study population, the SLIPA performed as well as an endotracheal tube in allowing positive pressure ventilation without gas leak during gynaecological laparoscopy. The way in which the SLIPA increases its resistance to gas leak as the inspiratory pressure rises may account for this.

Equipment to manage a difficult airway during anaesthesia

Airway complications are a leading cause of morbidity and mortality in anaesthesia. Effective management of a difficult airway requires the timely availability of suitable airway equipment. The Australian and New Zealand College of Anaesthetists has recently developed guidelines for the minimum set of equipment needed for the effective management of an unexpected difficult airway (TG4 [2010] www.anzca.edu.au/resources/professionaldocuments). TG4 [2010] is based on expert consensus, underpinned by wide consultation and an extensive review of the available evidence, which is summarised in a Background Paper (TG4 BP [2010] www.anzca.edu.au/ resources/professional-documents). TG4 [2010] will be reviewed at the end of one year and thereafter every five years or more frequently if necessary. The current paper is reproduced directly from the Background Paper (TG4 BP [2010]).

Pilot study of the air-Q intubating laryngeal airway in clinical use

The air-Q Intubating Laryngeal Airway (ILA) is a newly introduced extraglottic airway device. In this pilot study, we evaluated its use as a routine airway device during positive pressure ventilation. Ease of endotracheal intubation through the device was also assessed. Fifty-nine ASA I and II patients undergoing elective surgery received an air-Q ILA and an endotracheal tube where indicated. Insertion, ventilation and intubation characteristics were noted, as well as throat morbidity and occurrence of adverse events. An air-Q ILA was successfully inserted in 100% of patients. Mean leak pressure was 19 +/- 5 cmH2O. Endotracheal intubation was indicated in 19 patients and successful in 58% on the first attempt and 74% in total. Ten percent of the study patients were noted to have dysphagia. One patient was diagnosed with bilateral lingual nerve injury but made a complete recovery in four weeks. The air-Q ILA is an adequate extraglottic airway device in terms of insertion and ventilation. However the proposed advantage of ease of endotracheal intubation requires further investigation.

[Supreme laryngeal mask airway vs the I-gel supraglottic airway in patients under general anesthesia and mechanical ventilation with no neuromuscular block: a randomized clinical trial]

OBJECTIVE

The Supreme Laryngeal Mask Airway (SLMA) and the I-gel Supraglottic Airway (IGSA) are recently introduced devices incorporating a gastric channel. This study assessed the ease of insertion of the devices and their efficacy in mechanical ventilation.

MATERIAL AND METHODS

Eighty-five patients undergoing major outpatient surgery under general anesthesia were randomized to 2 groups for intubation using the SLMA or the IGSA. After induction of general anesthesia, the assigned mask was inserted and positioning was checked with a fiberoptic scope. Ease of insertion was evaluated. Seal pressure was measured and the following ventilatory parameters were recorded 10, 30, and 60 minutes after the start of surgery: peak pressure, mean pressure, compliance, and the ratio of tidal volume to respiratory frequency. Conditions at the moment of inserting the nasogastric tube were also noted.

RESULTS

First-attempt placement of the airway was possible in 95.2% of patients using the SLMA and in 86% using the IGSA (P = .147). The mean times required for placement were 27.1 seconds for the SLMA and 32.5 seconds for the IGSA (P = .195). The nasogastric tube was inserted on the first attempt in 97.6% of patients with an SLMA and in 85.7% of patients with an IGSA. The mean times required for tube insertion were 9.5 seconds through the SLMA and 22.1 seconds through the IGSA (P < .001). Seal pressure and compliance were similar in the 2 groups at the start of surgery and at 10, 30, and 60 minutes. The incidences of complications during surgery and at 90 minutes were likewise similar (P = .945 and P = .698, respectively).

CONCLUSIONS

The SLMA and the IGSA are easy to put into position on the first attempt. It is easier to insert the nasogastric tube through the gastric channel of the SLMA. Both devices provide an effective seal and the incidences of complications were similar for both in the patients we studied.

A comparison of the I-gel supraglottic airway as a conduit for tracheal intubation with the intubating laryngeal mask airway: a manikin study

BACKGROUND

Insertion of a supraglottic airway and tracheal intubation through it may be indicated in resuscitation scenarios where conventional laryngoscopy fails. Various supraglottic devices have been used as conduits for tracheal intubation, including the intubating laryngeal mask airway (ILMA), the Ctrach laryngeal mask and the I-gel supraglottic airway.

METHODS

A prospective study with 25 participants evaluated the success rate of blind intubation (using a gum-elastic bougie, an Aintree intubating catheter (AIC) and designated tracheal tube) and fibrescope-guided tracheal intubation (through the intubating laryngeal mask airway and the I-gel supraglottic airway) on three different airway manikins.

RESULTS

Twenty-five anaesthetists performed three intubations with each method on each of three manikins. The success rate of the fibrescope-guided technique was significantly higher than blind attempts (P<0.0001) with both devices. For fibreoptic techniques, there was no difference found between the ILMA and I-gel (P>0.05). All blind techniques were significantly more successful in the ILMA group compared to the I-gel (P<0.0001 for bougie, Aintree catheter and tracheal tube, respectively).

CONCLUSIONS

The results of this study show that, in manikins, fibreoptic intubation through both ILMA and I-gel is a highly successful technique. Blind intubation through the I-gel showed a low success rate and should not be attempted.

Airway management in the outpatient setting: new devices and techniques

PURPOSE OF REVIEW

There are an ever-increasing number of supraglottic airway devices available on the market, many being suitable for ambulatory surgery and the specific demands it creates. These include constraints of time, high turnover and the need for early and effective discharge. This article hopes to highlight the potential benefits of the current devices available.

RECENT FINDINGS

Laryngeal masks are still undoubtedly the most popular supraglottic devices available but there are an increasing number of other airways on offer. Advantages of these include higher seal pressures, ease of insertion and the ability to drain gastric fluids.

SUMMARY

Some of the unique advantages offered by certain devices lend themselves well to anaesthesia in ambulatory surgery. The laryngeal mask airway has a proven track record but newer airway devices are becoming more popular and may offer advantages. Further research is needed in this fast-moving field to assess these benefits, especially in specific cohorts of patients (such as the obese), who are appearing with increasing regularity on outpatient surgery lists.

Oesophageal seal of the novel supralaryngeal airway device I-Gel in comparison with the laryngeal mask airways Classic and ProSeal using a cadaver model

BACKGROUND

Supraglottic airway devices are increasingly used in anaesthesia and emergency medicine. This study was designed to investigate the oesophageal seal of the novel supralaryngeal airway device, I-Gel (I-Gel), in comparison with two of the laryngeal mask airways, Classic (cLMA) and ProSeal (pLMA), in a model of elevated oesophageal pressure.

METHODS

The three supralaryngeal airway devices were inserted into eight unfixed cadaver models with exposed oesophagi that had been connected to a water column producing both a slow and a fast oesophageal pressure increase. The pressure applied until the loss of oesophageal seal during a slow and fast pressure increase was measured.

RESULTS

During the slow increase of pressure, the pLMA withstood an oesophageal pressure up to a median of 58 cm H(2)O, while the cLMA was able to block the oesophagus up to a median of 37 cm H(2)O, and I-Gel already lost its seal at 13 cm H(2)O. One minute after maximum pressure had been applied, the pLMA withstood an oesophageal pressure of 59 cm H(2)O, the cLMA of 46 cm H(2)O, and I-Gel airway of 21 cm H(2)O. A fast release of oesophageal fluid was accomplished through the oesophageal lumen of both the pLMA and I-Gel.

CONCLUSIONS

Both the pLMA and cLMA provided a better seal of the oesophagus than the novel I-Gel airway. The pLMA and I-Gel drain off gastrointestinal fluid fast through the oesophageal lumen. Thus, tracheal aspiration may be prevented with their use. Further study is necessary.

Brief review: the Cobra Perilaryngeal Airway (CobraPLA and the Streamlined Liner of Pharyngeal Airway (SLIPA) supraglottic airways

PURPOSE

To summarize the published literature related to two, new supraglottic airways (SGAs): the Cobra Perilaryngeal Airway (CobraPLA) and the Streamlined Liner of Pharyngeal Airway (SLIPA).

SOURCE

We identified original articles, through searches on Medline and PubMed, using the keywords 'Cobra', 'CobraPLA', 'Cobra-PLA', 'PLA', and 'SLIPA'.

PRINCIPAL FINDINGS

Searches identified 28 publications evaluating the CobraPLA, six of which were randomized, controlled trials. Five publications evaluated the SLIPA, two of which were randomized, controlled trials. Studies compared the CobraPLA with a number of SGAs, in regards to both efficacy and safety. While the CobraPLA is comparable to the laryngeal mask airway (LMA) Classic, with respect to insertion times and the incidence and severity of sore throat, the CobraPLA is superior, with respect to airway sealing pressure, and has been used successfully in patients with limited mouth opening and limited head extension. Insertion times, first insertion success rates, recovery times, and hemodynamic responses, associated with insertion of the SLIPA, are similar to those of the LMA Proseal. Although the SLIPA has a unique reservoir chamber to contain regurgitated fluid, the extent of its protection against pulmonary aspiration has not been established in the clinical setting.

CONCLUSION

Both the CobraPLA and the SLIPA are intended for use during short procedures under general anesthesia, and have comparable efficacy and complication rates in comparison to the LMA Classic. Both airways may be considered as primary SGA devices, and the CobraPLA may be also be used as a rescue airway device.

Fiberoptic intubation through an I-gel supraglottic airway in two patients with predicted difficult airway and intellectual disability

We describe successful fiberoptic-guided tracheal intubation through the novel supraglottic "I-gel" airway in two uncooperative adult patients with genetic syndromes, learning disability, and predicted difficult airway, scheduled for complex dental treatment under general anesthesia. The I-gel maintained the airway immediately after induction, allowing oxygenation and ventilation. Location of the laryngeal inlet was successful on the first attempt with a fiberscope, and the tracheal tube was inserted into the trachea over the endoscope without complication in both patients. This report suggests another option for management of predicted difficult airways.

[The laryngeal tube]

The laryngeal tube (VBM Medizintechnic GmbH, Sulz, Germany) is a supraglottic device designed for airway management in spontaneous or positive-pressure ventilation during anesthesia or in cardiopulmonary resuscitation. Currently, the tube is available in 4 versions: the standard laryngeal tube, the disposable tube (LT-D), the dual-lumen tube (with a tube for suction) (LTS II), and the disposable LTS (LTS-D). The design of the tube has been modified several times. It is easy to insert and the airway seal is more effective than that of the laryngeal mask. The incidence of complications is similar for both devices, though use of the laryngeal tube requires more adjustments. The standard tube is somewhat less effective than the ProSeal laryngeal mask, though the new LTS II has been improved considerably. The laryngeal tube is effective as an aid to management of the difficult airway. We reviewed the literature indexed on MEDLINE through December 2006 using the search terms laryngeal tube, anesthesia, equipment, and airway.