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Table of Contents
LETTER TO EDITOR
Year : 2021  |  Volume : 37  |  Issue : 1  |  Page : 135-136

Failure of hinged tip laryngoscope due to design variation


Department of Anaesthesiology, Surgical intensive care, Pain and Palliative Care, Basavatarakam Indo-American Cancer Hospital and Research Institute, Hyderabad, Telangana, India

Date of Submission11-Nov-2019
Date of Acceptance26-Jan-2020
Date of Web Publication10-Apr-2021

Correspondence Address:
Dr. Vibhavari Milind Naik
Department of Anaesthesiology, Surgical Intensive Care, Pain and Palliative Care Basavatarakam Indo-American Cancer Hospital and Research Institute, Hyderabad - 500 073, Telangana
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/joacp.JOACP_374_19

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How to cite this article:
Naik VM, Rayani BK, Bharuka A. Failure of hinged tip laryngoscope due to design variation. J Anaesthesiol Clin Pharmacol 2021;37:135-6

How to cite this URL:
Naik VM, Rayani BK, Bharuka A. Failure of hinged tip laryngoscope due to design variation. J Anaesthesiol Clin Pharmacol [serial online] 2021 [cited 2021 May 6];37:135-6. Available from: https://www.joacp.org/text.asp?2021/37/1/135/313441

Dear Editor,

The hinged tip laryngoscope has been shown to improve the visualisation of the glottis in difficult airway. McCoy in 1993 patented the first design of levering laryngoscope. The tip bends upon pressing the lever to further lift the epiglottis. The mechanism of levering the tip is crucial for the defined and consistent performance of the blade. Failure of this mechanism during a difficult laryngoscopy can not only cause distraction during a crucial manoeuvre but also mucosal injury and/or foreign body in the airway.[1],[2] Sheeran et al. have reported this failure due to breakage of soldered part due to wear and tear.[3] Mechanical failure of hinged tip mechanism due to slipping of loaded spring has not been reported before. We report two cases of failure of hinged tip mechanism, which may be due to a design variation and compare it with another available design.

During an anticipated difficult laryngoscopy, upon pressing the lever, the lifting mechanism of Flexion blade (Scope Medical Devices Pvt Ltd, Ambala city, India) failed with a 'click'. The laryngoscope was immediately taken out and inspected for broken or missing components. The airway was inspected with a video laryngoscope to rule out injury and facilitate intubation. There was no injury or foreign body in the airway. [Figure 1] depicts the failure of hinged mechanism due to displaced loaded spring. The securement of loaded spring is of prime importance, which in this laryngoscope is poorly designed. [Figure 2] compares the variation in design of securing the spring in Flexion and Trupti blade (Anaesthetics India Pvt Ltd, Mumbai, India). The loaded spring in Trupti blade is curved around a rivetted screw along with two screws on either side providing more stability. Whereas, the open-ended spring rests on the blades in Flexion blade, which can slip and release the tension generated while the lifting mechanism is used. This design flaw predisposes it to failure. We had a similar malfunction with another blade of the same company. The blades were purchased one-year back and were autoclaved daily after cleaning with soap and water. There were no overt signs of wear and tear on the blades, as noted by the biomedical team.
Figure 1: Failure of hinged tip mechanism due to slipping of loaded spring. Spring labelled with pointer. A - Normal laryngoscope; B - Failed laryngoscope

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Figure 2: Dismantled laryngoscope blades to show design variation of securing the loaded spring. A - Flexion blade, Scope Medical Devices; B - Trupti blade, Anaesthetics India

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Anesthesiologists are trained to examine the equipment for integrity and function before use. We also need to be aware of design flaws, as noted in our case. Through this communication, we intended to create awareness amongst anesthesiologists regarding the design variations of hinged tip laryngoscopes and their implications in safety.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Galloway S, Cruickshanks A. Unusual complication of a McCoy bladed laryngoscope. Anaesthesia 2010;65:1151-2.  Back to cited text no. 1
    
2.
Jain A, Naithani M, Chaudhary Z, Sharma P. Rare iatrogenic airway foreign body: The rivet from the fulcrum of the McCoy laryngoscope blade. Indian J Anaesth 2012;56:301-2.  Back to cited text no. 2
[PUBMED]  [Full text]  
3.
Sheeran P, Maguire T, Browne G. Mechanical failure of the McCoy laryngoscope during difficult intubation. Anaesthesia 2000;55:184-5.  Back to cited text no. 3
    


    Figures

  [Figure 1], [Figure 2]



 

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