Inspite of equipment check by naked eye for routine procedure as recommended by ASTM still undetected anaesthesia equipment defects leading to its malfunctioning can occur compromising   patient safety. Multiple holes in endotracheal tubes are unusual and reported only once in literature. We detected two small holes at the junction of inflating tube of pilot balloon joining the endotracheal tube causing inadequate ventilation and low airway pressures in an anaesthetised patient undergoing surgery under general anaesthesia. Thus, it necessitates thorough preoperative check of new endotracheal tubes also, because such manufacturing errors are likely to be missed by naked eye [1,2,3,4,5].

A 50-year-old male patient diagnosed as a case of cholelithiasis posted for laparoscopic cholecystectomy was induced with intravenous anaesthetic agents propofol, fentanyl and atracurium after preoxygenation and switched over to a mixture of oxygen, nitrous oxide and sevoflurane. Patient was intubated with 8.5mm ID murphy’s eye cuffed, single use endotracheal tube (Sterimed medical devices, polyvinyl) the endotracheal tube’s cuff was inflated with 5ml air and mechanical ventilation initiated with a volume of 440 mL after checking bilateral air entry equal on both sides. Soon after we noticed gurgling sound, fall in Spo2 to 93 from 100%, peak airway pressure declined to 6 mm Hg from a preset value of 16 cm H₂O, a receding capnograph and low expired tidal volume (Vte) on the monitor. Continuous ventilator alarm was trigger on and on auscultation diminished B/L air entry was observed. When checked all circuit connections were in situ and there was no leak in any of the circuits. Pilot balloon of endotracheal tube was correctly inflated. We further inflated 2cc of air in the cuff,  still air leak was noted and noticed no improvement in ventilation. The patient’s ventilation was switched over to Bains circuit on auxiliary port but made no difference. Cuff pressure checked was 30mmHg.We immediately decided to change the ETT with a new 8.5mm I.D. cuffed ETT after checking manually before insertion. B/L air entry was checked and found to be normal. EtCo2 graph became normal. Patient was shifted to mechanical ventilator with same settings. Monitor showed normal ventilation, and normal peak airway pressure, without any gurgling sound, 100% SpO₂, cuff pressure 25 mmHg with new ETT. 

On examination of first endotracheal tube no defect was seen on inspection. There was no leak from cuff or pilot balloon on inflation with air. Then we straightened the endotracheal tube, occluded its patient end with finger and filled it water. We detected two small holes in its wall at the point of junction of inflation line with endotracheal tube. We observed water flowing out from both the orifices through the walls of endotracheal tube.

Figure 1: Pilot Balloon of Endotracheal Tube

Many a time’s manufacturing defects go unnoticed inspite of testing ETTs by naked eyes before use. Tube failure has been reported [1] undetected by routine testing, defective pilot balloon assembly [2], defects in cuff [3] kinking of ETT [4] undetected by naked eye has been reported in the past. Sofi et al., reported routine inspection of ETT might fail to detect some manufacturing defects like intraluminal plastic films, result in ventilation abnormalities after intubation and directly related to equipment error warranting remedial measures to ensure patient safety before anaesthetising the patient [5].

Routine naked eye inspections may fail to detect certain manufacturing defects which become evident only after initiation of mechanical ventilation as in our case .This emphasizes importance of standard monitoring of ventilation [6] and vigilance on part of anaesthesiologist in detecting any manufacturing defects, making double check of ETTs mandatory before using them, specially with more than one hole in the endotracheal tube.Singh at al reported a single hole in endotracheal tube and labelled it responsible for hypoventilation, hypoxia, awareness ,pollution of the operation theatre and ventilator failure causing death [6].  Incidences of occult and intra operative cuff leak in endotracheal tube is reported in the past in the middle of an ongoing surgery [7]. Avulsion due to weakening of inflation line of tube due to repeated autoclaving have been reported in a reused tube [8]. Thus, ventilatory complications are seen more frequently with improperly stored old, reused endotracheal tubes which are responsible for tracheal tube damage.

The ASTM/ISO standard requires that external diameter of inflation tube of the ETT not to exceed 2.5 mm and recommends that it has to be attached to the tube at a small angle. As per the standard’s specifications, distance from tip of the tube to where inflation tube is attached should have at least 3cm distance, that is between machine end of the inflation tube and pilot balloon.

Incidences of failure to detect manufacturing defects of a single hole with naked eye in routine inspection of ETT have been reported [3,9]. But none of the authors reported presence of two holes going unnoticed in endotracheal tube preoperatively by naked eye like us. Because the sizes of these holes were too small they went unnoticed by naked eye. Therefore we also suggest underwater testing of endotracheal tube prior to use, the test recommended by Sachdeva and Bhatia [9], in preventing accidents.   

We conclude that in this incidence routine inspection of the ETT and inflation of the cuff failed to detect two small holes on naked eye examination .Figure 2.Which resulted in significant air leak and hence impairment of ventilation and only on immersion in water were the leaks detected. Some manufacturing defects still go unnoticed, become evident only after initiation of mechanical ventilation.Although inspection of anaesthesia equipment prior to use is essential, we reaffirm that clinical assessment by the anaesthesiologist on table with proper and thorough checking of endotracheal tubes before use is the most important factor in confirming patient safety. 

1. Gettelman, T.A. et al. “Endotracheal Tube Failure: Undetected by Routine Testing.” Anesthesia & Analgesia, vol. 81, no. 6, 1995, pp. 1313.

2. Baduni, N. et al. “Malfunctioning Pilot Balloon Assembly.” Journal of Anaesthesiology and Clinical Pharmacology, vol. 29, no. 1, 2013, pp. 131–132.

3. Arya, V.K. et al. “All That Seems Well Is Not Well Always—Intermittently Malfunctioning Flexo-Metallic Tracheal Tube.” British Journal of Anaesthesia, vol. 93, no. 3, 2004, pp. 478–479.

4. Chua, W.L., and A.S. Ng. “A Defective Endotracheal Tube.” Singapore Medical Journal, vol. 43, no. 9, 2002, pp. 476–478.

5. Sofi, K., and K. El-Gammal. “Endotracheal Tube Defects: Hidden Causes of Airway Obstruction.” Saudi Journal of Anaesthesia, vol. 4, no. 2, 2010, pp. 108–110.

6. Singh, P.M. et al. “An Unusual Site of Leak in Anaesthesia Circuit.” Anaesthesia, Essays and Researches, vol. 6, no. 1, 2012, pp. 111.

7. Kapoor, D., and A. Singh. “An Unusual Site of an Occult Air Leak in an Armoured Endotracheal Tube in the Midst of Surgery.” Indian Journal of Anaesthesia, vol. 56, no. 1, 2012, pp. 99–100.

8. Bhandari, S. et al. “Accidental Intraoperative Avulsion of External Inflation Tubing of Armored Endotracheal Tube.” Journal of Anaesthesiology Clinical Pharmacology, vol. 28, no. 1, 2012, pp. 132–133.

9. Sachdeva, R., and N. Bhatia. “All That Appears Well Is Not Well: A Novel Method to Detect an Unusual Manufacturing Defect of the Endotracheal Tube.” Journal of Anaesthesiology, Clinical Pharmacology, vol. 31, no. 4, 2015, pp. 562.