Eliminating protein from reusable laryngeal mask airways. A study comparing routinely cleaned masks with three alternative cleaning methods

Protein Contamination of the Laryngeal Mask Airway and its Relationship to Re-use

The Laryngeal Mask Airway is a reusable device for maintaining the patency of a patient's airway during general anaesthesia. The device can be reused after it has been cleaned and sterilized. Protein contamination of medical instruments is a concern and has been found to occur despite standard sterilization techniques. The reason for the concern relates to the possibility of the transmission of prions and the risk of developing a neurodegenerative disorder such as Creutzveldt-Jacob disease. The purpose of this study was to quantify the amount of protein contamination that occurs, and to relate this to the number of times the Laryngeal Mask Airway has been used. Fifty previously used Classic Laryngeal Masks were collected after routine sterilization and packaging. The devices were immersed in protein detecting stain and then visual inspection performed to assess the degree and distribution of the staining. The researcher was blinded to the number of times the Laryngeal Mask Airway had been used. Linear regression analysis of the degrees of staining of the airway revealed that protein contamination occurs after the first use of the device and this increases with each subsequent use. This finding highlights the concern that the currently used cleaning and sterilization methods do not prevent the accumulation of proteinaceous material on Laryngeal Mask Airways. Consideration should be given to the search for more efficient cleaning and sterilization techniques or the use of disposable devices.

Evaluation of the SLIPA™ (Streamlined Liner of the Pharynx Airway), a Single Use Supraglottic Airway Device, in 60 Anaesthetized Patients Undergoing Minor Surgical Procedures

The Streamlined Liner of the Pharyngeal Airway, SLIPA™ (Hudson RCI) is a new disposable supraglottic airway device that has no inflatable cuff and has features designed to reduce aspiration risk. This study aimed to assess the insertion success and effectiveness of the SLIPA™ in 60 patients who presented for elective surgery. Ethics committee approval was obtained. Patients were excluded if they were less than 18 years, had not provided written consent or were at risk of pulmonary aspiration. The first 20 SLIPA™ were inserted by the principal investigator (Group A) followed by another 40 inserted by medical officers and anaesthetists of varying experience (Group B). Twenty-one males and 39 females were recruited into the study. Median time to ventilation was 20.4 seconds in Group A (range 12.9-109) and 24.8 seconds in Group B (range 8.2-82.5). Overall success rate was 100% in Group A and 92.5% in Group B. The lowest recorded SpO2 was 91% in Group B. The incidence of blood and sore throat score >3 (0-10 scale) was 23% and 7% respectively (Groups A and B). Group B reported that use of the device was very easy in 16%, easy in 76%, difficult in 5%, and very difficult in 3%. The SLIPA™ proved to be a reliable airway providing adequate ventilation in both spontaneous breathing and assisted respiration. Most users found the SLIPA™ to be easy or very easy to use.

A Survey of Current Practice of Supraglottic Airway Devices in Pediatric Anesthesia from India

Background and Objectives:

Supraglottic airway devices (SADs) have revolutionized the pediatric anesthetic practice and got a key role in difficult airway (DA) management. Several modifications of SADs design had come up to improve their safety.

Aim:

The aim of this survey was to determine the current usage of SADs in pediatric anesthetic practice, their availability, and to know any difficulties noted in practice.

Methods:

It was a questionnaire survey among the anesthesiologists who attended the National Pediatric Anesthesia Conference-2016. The questionnaire assessed the current practice preferences of SADs in routine pediatric cases and DA management, availability of various devices, and any difficulties noted in their usage.

Results:

First-generation SADs were widely available (97%), and 64% of respondents preferred to use it for pediatric short cases. 64% felt the use of SADs free their hands from holding the facemask and 58% found better airway maintenance with it. Intraoperative displacement (55%) was the common problem reported and only 11% felt aspiration as a problem. Most of the respondents (73%) accepted its use as rescue device in airway emergency, and 84% felt the need of further randomized controlled studies on safety of SADs in children. The majority were not confident to use SADs in neonates.

Interpretation and Conclusions:

The key role of SADs in DA management was well accepted, and aspiration was not a major problem with the use of SADs. Although many newer versions of SADs are available, classic laryngeal mask remains the preferred SAD for the current practitioner. Further, RCTs to ensure the safety of SADs in children are warranted.

Small is the new big: An overview of newer supraglottic airways for children

Almost all supraglottic airways (SGAs) are now available in pediatric sizes. The availability of these smaller sizes, especially in the last five years has brought a marked change in the whole approach to airway management in children. SGAs are now used for laparoscopic surgeries, head and neck surgeries, remote anesthesia; and for ventilation during resuscitation. A large number of reports have described the use of SGAs in difficult airway situations, either as a primary or a rescue airway. Despite this expanded usage, there remains little evidence to support its usage in prolonged surgeries and in the intensive care unit. This article presents an overview of the current options available, suitability of one over the other and reviews the published data relating to each device. In this review, the author also addresses some of the general concerns regarding the use of SGAs and explores newer roles of their use in children.

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.

A critique of elective pediatric supraglottic airway devices

In 1988, when the Laryngeal Mask Airway-Classic (Intavent Orthofix, Maidenhead, UK), was introduced there were only two choices of airway management: tracheal tube or facemask. The supraglottic airway, as we now understand the term, did not exist. Yet, 20 years later, we are faced with an ever increasing choice of supraglottic airway devices (SAD). For many SADs, with the exception of the LMA-Classic and LMA-Proseal (Intavent Orthofix, Maidenhead, UK), there is a lack of high quality data of efficacy. The best evidence requires a randomized controlled trial comparing a new device against an established alternative, properly powered to detect clinically relevant differences in clinically important outcomes. Such studies in children are very rare. Safety data is even harder to establish particularly for rare events such as aspiration. Therefore, most safety data comes from extended use rather than high quality evidence which inevitably biases against newer devices. For reason of these factors, claims of efficacy and particularly safety must be interpreted cautiously. This narrative review aims to present the evidence surrounding the use of currently available pediatric SADs in routine anesthetic practice.

The effect of high concentration potassium permanganate on protein contamination from metallic and synthetic rubber airway equipment

We tested the hypothesis that supplementary cleaning using potassium permanganate 8 mg.l(-1) eliminates protein deposits from the reusable metallic and synthetic rubber airway equipment. Twenty Macintosh laryngoscope blades (surgical steel), 20 pairs of Magill's forceps (surgical steel) and 20 Guedel airways (synthetic rubber) were allocated to two groups for supplementary cleaning. In group A, the device was immersed in potassium permanganate 8 mg.l(-1). In group B (controls), the device was immersed in sterile water. The devices were then immersed in a protein staining solution, rinsed and the severity of staining was scored. In addition, the devices were inspected for tissue and then tested for occult blood. Protein contamination was lower in the potassium permanganate group for all devices (each device: p < 0.0001). There was no staining detected in the permanganate group. In the permanganate group, dried tissue was detected in the teeth of one pair of forceps, which was not detected following supplementary cleaning. Additionally, occult blood was detected on two pairs of forceps and a laryngoscope blade, which was not detected following supplementary cleaning. In the control group, no tissue was detected but one pair of forceps and two laryngoscope blades tested positive for occult blood before and after supplementary cleaning. We conclude that supplementary cleaning using potassium permanganate 8 mg.l(-1) eliminates protein deposits from re-usable metallic and synthetic rubber airway equipment.

The use of single-use devices in anaesthesia: balancing the risks to patient safety

Single-use devices are designed, manufactured and sold to be used once and then discarded. This paper addresses growing concerns about the quality of some devices. Single-use devices, manufactured at a lower cost to justify their disposal, are perceived to have a lesser efficacy, which may threaten patient safety through iatrogenic harm. There is, in addition, growing scepticism about the actual risk of contracting variant Creutzfeldt-Jakob disease and other blood-borne diseases from reused surgical instruments. Interview data suggests that when choosing to use a single-use device, clinicians balance concerns about the risk of infection against those about the risk of injury. However, despite reservations about induced harm and the unknown risk of an iatrogenic disease, most clinicians would want single-use devices used on themselves and their family if they were patients.

The effectiveness and patient comfort of the novel streamlined pharynx airway liner (SLIPA) compared with the conventional laryngeal mask airway in ophthalmic surgery

BACKGROUND

The novel, disposable streamlined pharynx airway liner (SLIPA) has recently been introduced into clinical practice. It has no inflatable cuff, because the shape of the SLIPA closely resembles the anatomy of the pharynx.

METHODS

We compared the SLIPA with the conventional laryngeal mask airway (LMA) regarding handling, safety, sealing of the pharynx, and patient comfort in 124 adult patients (ASA I-III) undergoing ophthalmic surgery under general anesthesia.

RESULTS

Insertion of the SLIPA was straightforward in 88%, slightly difficult in 10%, and obviously difficult in 0% of cases. The SLIPA could not be inserted in 2% of patients. In the LMA group, insertion was straightforward in 90%, slightly difficult in 8%, obviously difficult in 2%, and a failure in 0% of patients. Maximum seal pressure was 24 +/- 6 mm H2O with the SLIPA and 24 +/- 4 mm H2O with the LMA. Gastric air insufflation was noticed in 19% of patients in the SLIPA group and 3% in the LMA group (P < 0.05). No regurgitation of gastric contents was observed. Removal of the airway was uneventful in all cases. Blood traces were noted on the surface of the device in 20% in the SLIPA versus 11% (n.s.) in the LMA group. Complaints of a sore throat were recorded in 2% vs. 14% in the SLIPA and the LMA group, respectively.

CONCLUSION

The SLIPA is a useful alternative to the conventional LMA in patients undergoing minor surgery. However, it is associated with a higher incidence of gastric air insufflation, which may increase the risk of aspiration.

High concentration potassium permanganate eliminates protein and particle contamination of the reusable Classictm laryngeal mask airway

In this three-stage study, we test the hypothesis that supplementary cleaning with potassium permanganate > or =4 mg.l(-1) eliminates protein and particle contamination from the reusable Classic laryngeal mask airway. The first stage involved supplementary cleaning of 70 1 x 1 cm segments from deliberately contaminated laryngeal mask airways using potassium permanganate at 0, 2, 4, 8, 16, 32 and 64 mg.l(-1) and testing for protein staining. This showed that the lowest concentration required to eliminate protein contamination was 8 mg.l(-1). The second stage involved supplementary cleaning of 50 used laryngeal mask airways with either potassium permanganate 8 mg.l(-1) or saline and testing for protein staining. This showed that protein contamination was lower in the potassium permanganate group (p < 0.00001): all laryngeal mask airways in the control group and none in the potassium permanganate group were contaminated. The third stage involved scanning electron microscopic examination of 1 x 1 cm segments from three laryngeal mask airways used in the control group, three from the potassium permanganate group, plus three brand new laryngeal mask airways. The mean density of > or =1 mum surface particles was lower in the potassium permanganate 8 mg.l(-1) than the control group (21 vs. 121 .cm(-2), p < 0.0001) and was similar to brand new laryngeal mask airways (24 .cm(-2)). We conclude that supplementary cleaning with potassium permanganate 8 mg.l(-1) eliminates protein deposits from reusable laryngeal mask airways and reduces particle contamination to similar levels to brand new laryngeal mask airways.

Protein cross-contamination during batch cleaning and autoclaving of the ProSeal laryngeal mask airway

We tested the hypothesis that protein cross-contamination occurs during batch cleaning and autoclaving of a reusable extraglottic airway device, the ProSeal laryngeal mask airway. At the end of each day for 10 days, nine laryngeal mask airways that had been used for non-intra-oral surgery were cleaned and autoclaved alongside a new unused laryngeal mask airway. In addition, a new unused laryngeal mask airway underwent the same cleaning and autoclaving procedures in isolation. Protein staining was more frequently detected on the unused laryngeal mask airways that were processed by batch rather than in isolation (p < 0.01). Protein staining was detected on all unused laryngeal mask airways that were processed by batch, but none on those processed in isolation. Protein staining was more severe with the used compared with the unused laryngeal mask airways (p < 0.001). We conclude that protein cross-contamination of the laryngeal mask airway occurs during batch cleaning and autoclaving and recommend that reusable airway devices are cleaned in isolation.

Repeat autoclaving does not remove protein deposits from the classic laryngeal mask airway

INTRODUCTION

We tested the hypothesis that repeated autoclaving removes protein deposits from the classic laryngeal mask airway (LMA).

METHODS

Twenty previously used LMAs were hand washed, machine washed, dried, autoclaved and randomly allocated into four equal-sized groups for repeat autoclaving on 0 (control), 1, 2 and 3 occasions. After the final autoclave cycle, the LMAs were immersed in a protein-staining solution, rinsed, dried and a high-resolution digital image taken of the dorsal and ventral surfaces. The severity of staining was scored by two blinded observers.

RESULTS

All LMAs were stained. There was no reduction in staining with repeat autoclaving.

CONCLUSIONS

Repeat autoclaving does not remove protein deposits from the LMA.

Potassium Permanganate Reduces Protein Contamination of Reusable Laryngeal Mask Airways

We tested the hypothesis that supplementary cleaning with potassium permanganate 2 mg/L eliminates protein deposits from reusable laryngeal mask airways (LMAs). Sixty previously used classic LMAs were hand-washed, machine-washed, dried, autoclaved, and then randomly allocated into two groups for supplementary cleaning. In Group A, the cuff was immersed in potassium permanganate 2 mg/L at 20 degrees C for 20 min. In Group B (control), the cuff was immersed in sterile water at 20 degrees C for 20 min. After supplementary cleaning, the LMAs were immersed in a protein staining solution and rinsed, and a high-resolution digital image was taken of the dorsal surface. The severity of staining was scored by an observer blinded to the type of supplementary cleaning. The severity of protein contamination was reduced after supplementary cleaning in potassium permanganate (P < 0.00001). Protein contamination was detected on 20% of LMAs after supplementary cleaning in potassium permanganate, compared with all LMAs in the control group. We conclude that supplementary cleaning with potassium permanganate 2 mg/L does not eliminate protein deposits from all LMAs, but it does reduce the number of devices contaminated from 100% to 20%.