Clinical alert: failure in face mask seal as a consequence of incorrect face mask assembly

S. F. McDouall1, R. C. Campbell1, R. C. Tasker1, J. R. Smart2 and N. S. Bradbury2

1 Cambridge, UK 2 Orpington, UK

Editor—We are reporting two case scenarios, highlighting the failure of a face mask. On each occasion, the equipment had been checked by both a trained health worker and the anaesthetist without detection of the flaw. Neither patient died but the near-miss was sufficiently alarming to provoke this report. We seek to raise awareness amongst colleagues of the potential problems with this particular face mask. In both instances, the equipment being used was taken from supplies provided by the Central Sterile Stores Department (CSSD).

Case 1
A 9-year-old boy was managed on the Paediatric Intensive Care Unit after a road traffic accident. He was undergoing intracranial pressure (ICP) monitoring. His oral endotracheal tube was too short and needed replacement. The intubation trolley, which had been checked routinely that morning, was used to supply the laryngoscope, mask and tracheal tube. After routine preparation, the patient’s tracheal tube was removed and replaced. It was quickly realized that this new tube had been placed in the oesophagus necessitating its removal and bag-valve-mask ventilation. The registrar was unable to ventilate the patient and tried to improve the seal with no success. After a short period, it was realized the mask had a fault, with a missing fixture leaving an uncovered hole in the side (Fig. 1A and B). This made the mask impossible to use. A different mask was found and used effectively. During this interval of ineffective ventilation, the ICP rose dramatically. After re-intubation, the ICP decreased to less that 20 mm Hg.



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Fig 1 (A) Two-piece Laerdal mask showing the component parts side-on. (B) Assembled mask showing the absence of a rubber flange (see arrow), which was responsible for equipment failure in Case 1. (C) Correctly assembled mask en face. (D) Incorrectly assembled mask on too small a face-piece. The arrows indicate the gap responsible for equipment failure in Case 2.

 
Case 2
An 8-year-old boy, an inpatient on the oncology ward, required a general anaesthetic for a diagnostic lumbar puncture, bone marrow sampling and placement of a Hickmann line. The procedure was being performed in a day care ward surgical area. He had an i.v. induction using propofol and atracurium. After induction, an attempt was made to ventilate the child using the given face mask (Fig. 1C and D). Due to the large leak, secondary to incorrect mask assembly, it was not possible to support ventilation. There was no intubation trolley nearby and therefore no other mask was available. The child was intubated immediately, despite the lack of full paralysis and therefore under suboptimal intubation conditions. There was a significant desaturation but the child ultimately came to no harm.

Using two-piece autoclavable masks can lead to two different problems, not immediately apparent, that can potentially lead to a critical incident. These flaws, obvious once pointed out, are not necessarily so obvious in an emergency. The situation is more dangerous if the person using the mask is not familiar with airway skills and is therefore slower to detect an equipment failure. In our cases, the first problem arose from the loss of a rubber flange, leaving a hole in the side of the mask. This was easily spotted once the possibility of equipment failure was considered. The second flaw was more subtle and consisted of a size 3 mask part being assembled with a size 4 outer part. To our knowledge, these children came to no harm. However, had the flaws not been detected quickly and a suitable alternative method of ventilation found, this would not have been so.

Following these cases, the policy in our hospital has changed to using one-piece Laerdal masks on all intubation trolleys. We have publicized this potential equipment failure of the Laerdal two-piece autoclavable mask around our hospital. The purpose of this ‘clinical alert’ is to raise awareness in clinicians and hospitals using the two-piece Laerdal mask; the manufacturers have also been informed. Our recommendation is that use of such masks should cease and that one-piece masks should be used instead. It is of note that the two-piece masks were discontinued by Laerdal in 1999 in favour of the one-piece mask.

S. F. McDouall

R. C. Campbell

R. C. Tasker

Cambridge, UK

Editor—Mis-assembly and failure of resuscitation equipment is an extremely serious event and one that Laerdal responds to with the highest priority.

The two-piece face mask described in this letter has been widely sold and copied by a number of other manufacturers. The original Laerdal two-piece face mask, when correctly re-assembled according to the directions for use, has proven to be a reliable and dependable product. Errors in re-assembly such as described have thankfully been extremely rare and no discernible trend has been observed. As stated in the directions for use (p. 21), Laerdal recommends that all parts are carefully inspected for damage or excessive wear and re-assembled according to the pictorial instructions (p. 14 and 22).

As correctly highlighted in this letter and in line with our policy of continual product development, the manufacture and distribution of this type of two-piece face mask was discontinued in 1999. The new face mask is easier to clean and has other improvements, which were not prompted by this type of incident. These errors in re-assembly would not have occurred with our current face mask.

We thank the authors for highlighting these potentially dangerous incidents that demonstrate the importance of equipment checks being performed by adequately trained personnel and that such equipment is only used by experienced practitioners.

J. R. Smart1

N. S. Bradbury2

1Managing Director, Laerdal Medical Ltd, Orpington, UK

2Clinical Support Manager, Laerdal Medical Ltd, Orpington, UK





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