Reservoir Bag Neck Defect Causing Apparent ‘Tight Bag’ During Mask Ventilation

To the Editor, ‘Tight bag’ during mask ventilation is an alarming clinical scenario, usually attributed to bronchospasm, endobronchial intubation or mechanical obstruction of the airway or circuit. Rarely, a structural defect of the reservoir bag, particularly an absent protective neck reinforcement, leading to twisting, may be responsible.[1] We report a case in which an elongated, unsupported neck without the usual plastic protective cage of reservoir bag resulted in twisting of the bag at the neck during mask ventilation, producing an apparent inability to ventilate situation and causing undue anxiety. This case is reported after obtaining informed consent from the patient. A 15-year-old, 54 kg male scheduled for pinnaplasty was induced with fentanyl 150 μg, propofol 100 mg and atracurium 30 mg. Bag–mask ventilation was initiated with the adjustable pressure-limiting (APL) valve set at 20 cm H2O. Initially, adequate tidal volumes (350–400 mL) were delivered. However, within a minute, after repositioning the face mask to minimise leak, the reservoir bag became unusually tight and delivered negligible tidal volumes (<80–100 mL), despite optimal technique and adjuncts. We changed the operator, applied two-hand mask ventilation, deepened the anaesthetic plane and inserted an oropharyngeal airway, yet the inability to ventilate persisted. Oxygen saturation remained 100%. Rapid assessment excluded bronchospasm and circuit kinking. Closer inspection then revealed twisting of the reservoir bag around its neck due to an absent protective plastic reinforcement. The twisting occurred when the bag was transferred between operators, during which torsional force rotated the elongated unsupported neck, a mechanism not evident on routine preuse checks. Derotation of the bag immediately restored ventilation, and tracheal intubation was performed uneventfully. The reservoir bag was replaced with a newer one. The defective bag and a reference bag from the same manufacturer were subsequently compared. Examination confirmed a longer unsupported neck, absence of the integrated support cage and identical batch and product specifications. Both the bags were Anaesthesia Green Rebreathing Bags manufactured by Medisafe International (MSI) {model MSI 1065 -1068;ISO 9001:2015,ISO 13485:2003,World Health Oraganisation-GMP(good manufacturing practices) and CE (conformity european)}[Figure 1].Figure 1: (a) Twisting of defective reservoir bag around unsupported neck producing a tight bag. (b) Left: Defective reservoir bag; right: normal reservoir bag with intact protective cage. (c) Protective cage integrated into a 22 mm connector, providing neck reinforcementWe have the Dräger Primus anaesthesia workstation. Routine prechecks are performed as per the manufacturer’s recommendations. This defect escaped detection because standard preuse testing assesses leak integrity and compliance but does not apply torsional forces that would expose rotational instability of the reservoir bag neck. During mask ventilation, the combination of a tight mask seal, high fresh gas flow, APL at 20 cm H2O and the mechanically rotated unsupported neck produced airway pressures of 18–20 cm H2O with minimal delivered tidal volume until the defect was identified. Similar circuit-related malfunctions have been described previously.[2-5] This case highlights the importance of equipment design consistency, quality control variability amongst manufacturers and the need for procurement protocols that ensure reinforced neck structures in reservoir bags. Manufacturers should ensure reliable neck support to prevent such hazardous twisting. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that his name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed. Author contribution Ram Singh and Muskan Agrawal came up with an idea to publish the report, Ram Singh and Muskan Agrawal conceptuaised and designed the study. Muskan Agrawal and Kapeesh Indora wrote the initial draft and searched the literature, Ram Singh and Prakash Gyandev Gondode approved the final manuscript draft and supervised the overall drafting of the manuscript. Disclosure of use of artificial intelligence (AI) and use of permitted tools ChatGPT 5.2 was used to edit language and grammar while preparing the manuscript. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.