From the *Department of Anesthesiology, Ruth and Bruce Faculty of Medicine, Technion-Israel Institute of Technology; and †Department of Anesthesiology, Rambam Health Care Campus, Haifa, Israel.
Nazarena Mazzaro, MSc Biomed Eng, PhD, Director Clinical Research and Biosafety, Ambu A/S NAM@ambu.com
Accepted for publication June 25, 2013.
The authors declare no conflict of interest.
Address correspondence to Yeshayahu (Shai) Katz, MD, DSc, Department of Anesthesiology, Rambam Health Care Campus and the Ruth and Bruce Faculty of Medicine, Technion-Israel Institute of Technology, Bat Galim, Haifa, 35254, Israel. Address e-mail to email@example.com.
One day after removal of an AuraStraight disposable laryngeal mask, a plastic laryngeal mask airway cuff shield was retrieved from the oropharynx of a 5-year-old child refusing to eat, drooling, and pointing to her throat. We discuss the reasons why this occurred and suggest how it can be prevented in the future.
We describe a complication occurring as the result of a packaging component remaining in the oropharynx after removal of a supraglottic airway device. Since the family of the girl had already left the hospital, we received approval by telephone from the mother to publish this report.
A 5-year-old girl underwent general anesthesia for magnetic resonance imaging of suspected nephroblastoma. An appropriate size laryngeal mask airway ([LMA], pediatric #2 AuraStraight disposable laryngeal mask, Ambu A/S, Ballerup, Denmark) was removed from its original package, lubricated and easily slid into position after IV propofol administration. The LMA cuff was inflated as instructed. At the end of an uneventful procedure, the LMA cuff was deflated and smoothly removed. During the recovery period, she complained of a strange feeling in her throat which was related by the anesthesiologist as a common report of unpleasantness after airway manipulation. The girl was discharged to the ward where she refused to eat, drooled, and pointed to her throat. No other signs of upper airway problems were noted. Oral and pharyngeal examination by a head and neck surgeon did not reveal any grossly abnormal findings. However, because symptoms persisted, the following morning, the surgeon conducted oropharyngeal fiberoptic bronchoscopy under sedation and extracted a white half round and pointed plastic structure which was found to be the LMA cuff shield, designed by the manufacturer to support the shape of the cuff while in storage (Fig. 1). The pharyngeal mucosa appeared slightly edematous, without notable injury. Post–case analysis revealed that the anesthesiologist who inserted the LMA did not separate the shield from the cuff, as should have been done but positioned them both, the cuff and the attached shield as 1 unit, into the airway.
LMAs are produced by several different companies. Every manufacturer constructs its brand uniquely. Nevertheless, in our opinion, there is a conceptual error in the basic design of the AuraStraight disposable laryngeal mask. It consists of 2 separate parts, assembled into a single joined unit which when drawn out of the package might lead the operator to erroneously think it is 1 piece. Amazingly, the presence of the shield within the hypopharynx did not affect the quality of ventilation.
Interestingly, in vitro when the cuff is inflated, it presses onto the shield and creates a firm block. When deflated, the cuff slides out of the shield easily. In our patient, the LMA was placed inflated and removed deflated, which may have contributed to the mistake of leaving the shield inside her pharynx. In addition, in the company product datasheet, the subject of the LMA cuff shield is not mentioned, and therefore, there are no explicit instructions to remove it before use.a
We believe that the AuraStraight disposable laryngeal mask should be available for use without accessory components linked to it. If the designer wants to reinforce the LMA cuff, there are several solutions available. It can be done easily by building an enclosing blister that will preserve the desired cuff architecture or with a shield significantly different in shape, color, or width from the LMA cuff. Nevertheless, there should be a warning on the package stating that this LMA comprises 2 parts that must be separated beforehand, as well as simple and clear, illustrated guidance explaining product operation.
MANUFACTURER’S RESPONSE TO “A CALL OF ALERT FOR THE AMBU AURASTRAIGHT DISPOSABLE LARYNGEAL MASK”
The authors suggest that this incident is due to a “conceptual error in the design of the Ambu AuraStraight” and that there is no explanation in the device datasheet that the cuff protector has to be removed before inserting the device.
First and foremost, we regret that the young patient suffered this unnecessary painful and stressful experience. Second, we thank the authors for reporting this case because it will allow us to reevaluate the device packaging. Third, we would like to thank the editors of Anesthesia & Analgesia for allowing us to respond, since we believe that analyzing usability errors contribute to the improvement of instrumentation and patient care routines. However, we would like to clarify the following 3 points:
1. The datasheet mentioned by the authors is a 1-page commercial leaflet available at the Ambu website that emphasizes the product features. It is not provided with the device, and it is not intended, nor referenced, as the device instruction for use. The device “Instructions for use” is printed at the back of the packaging of each device indicating the basic steps in the preparation and use of a laryngeal mask. The pictograms show that the cuff has to be deflated completely before use, since, as the authors write in their case report “When deflated, the cuff slides out of the shield easily.” Moreover, the AuraStraight Product Information states the following: “1. Warnings/Cautions: All AmbuStraight masks must, prior to use, be investigated and inspected for any potential foreign body. The cuff protector only serves as protecting the AmbuStraight during storage and transportation and must be removed prior to use.” (http://www.ambu.com/corp/products/anaesthesia/product/aurastraight™_disposable_laryngeal_mask-prod879.aspx. Page 4)
2. The authors write that the device consists of “two separate parts, assembled into a single joined unit.” We believe this sentence is misleading since, as shown in Figure 1C, the device consists of 1 piece made of green soft PVC, while the cuff protector is a piece of white rigid polyethylene that slides out when the cuff is deflated.
3. As pointed out by the authors, the cuff protector is aimed to shield the device’s cuff preventing deformation during transportation and storage; since any cuff deformation can affect the device seal properties. In fact, the main brands of laryngeal masks have similar cuff protectors as part of the packaging. This can partly explain the fact that only within the last year >1 million AuraStraight devices have been used worldwide, and no single case similar to the one described here has been reported, neither within this period nor since the device has been placed on the market in 2007.
Once again, we are sorry for the unpleasant situation suffered by the young patient and her family. And while we will reevaluate the design of the packaging to help prevent events like this in the future, we would like to make it clear that we do not believe that this incident was caused by a poor design of the device packaging or by an incomplete description of its use.
a Available at: http://www.ambu.com/corp/products/anaesthesia/product/aurastraight%E2%84%A2_disposable_laryngeal_mask.aspx Cited Here...