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Year : 2007  |  Volume : 51  |  Issue : 5  |  Page : 432 Table of Contents     

Ventilatory Obstruction with Spiral Embedded Tube - Are They as Safe?

1 M.D, Senior resident, Department of Anaesthesiology and Critical Care, Govt. Medical College ,Jammu, J&K, India
2 M.D, Professor, Department of Anaesthesiology and Critical Care, Govt. Medical College ,Jammu, J&K, India
3 M.D, Professor and Head, Department of Anaesthesiology and Critical Care, Govt. Medical College ,Jammu, J&K, India

Date of Acceptance25-Aug-2007
Date of Web Publication20-Mar-2010

Correspondence Address:
Dinesh Malhotra
Department of Anaesthesiology and Critical Care, Govt. Medical College ,Jammu, J&K
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Source of Support: None, Conflict of Interest: None

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Spiral embedded tubes are routinely being used in anaesthetic practice these days as a preventive measure in cases where kinking of the endotracheal tube is anticipated. In spite of this advantage spiral embedded tubes can at times lead to disaster since any deformity in these tubes is permanent and leads to occlusion of a patent airway.
We present a 40-year-male, who underwent popliteal artery anastomosis for a tear after fire arm injury, under general anaesthesia with spiral embedded tube in prone position. Surgical procedure and anaesthesia was uneventful but before extuba­tion, patient bite on the tube created permanent deformity resulting in occlusion, leading to hypoxia and desaturation. The deformed tube was removed and replaced with an LMA, thereafter the patient was managed without any complications or sequelae and a lesson was learnt.

Keywords: Spiral embedded tube; Armoured, Flexometallic; Obstruction

How to cite this article:
Malhotra D, Rafiq M, Qazi S, Gupta SD. Ventilatory Obstruction with Spiral Embedded Tube - Are They as Safe?. Indian J Anaesth 2007;51:432

How to cite this URL:
Malhotra D, Rafiq M, Qazi S, Gupta SD. Ventilatory Obstruction with Spiral Embedded Tube - Are They as Safe?. Indian J Anaesth [serial online] 2007 [cited 2021 Mar 3];51:432. Available from: https://www.ijaweb.org/text.asp?2007/51/5/432/61177

   Introduction Top

Spiral embedded tube, also known as flexometallic or armoured tubes is useful in conditions where kinking or compression of the tube can pose a problem intraop­eratively [1] . These tubes are routinely being used for sur­gical procedures involving head and neck, trachea, neu­rosurgical operations and surgeries done in prone posi­tion. These tubes can be easily angled away from the surgical site without getting kinked. Though these tubes are certainly useful, problems may also be associated with them. This case report describes compression of an armoured tube during a popliteal artery anastomosis.

   Case report Top

A 40-year-old male, with insignificant past medical history, came with firearm injury in popliteal region and fractured tibia. He was taken up for popliteal artery anas­tomosis. General anaesthesia was induced with sodium thiopentone 4mg.kg -1 , morphine 0.15 mg.kg -1 . Tracheal intubation with spiral embedded endotracheal tube (Portex Safety Flex; expiry date February 2007) of 8.00 mm ID, was achieved using rocuronium 0.6 mg.kg -1 . After securing the tube, patient was turned prone for surgery. Normal breath sounds were heard equally in both lungs. Anaesthesia was maintained with 67% ni­trous in oxygen and halothane (1-2%). The intraoperative course was uneventful and the surgery lasted for 4 hours. At the end of surgical procedure patient was turned supine. Inhalational agents were stopped and patient was ventilated with 100% oxygen. Neuromuscular blockade was reversed using neostigmine 0.04 mg.kg -1 and atro­pine 0.02 mg.kg -1 after the third response of train of four stimuli was noted on peripheral nerve stimulator. Sud­denly the peak inspiratory pressure started to increase while compliance and tidal volume decreased, patient started to desaturate and, capnograph showed a positive deflection on the inspiratory phase. Retraction of chest was noted with respiratory movements; on chest aus­cultation no air entry was found. A suction catheter was passed to check any compromise in the patency of the endotracheal tube. It was noted that the catheter did not pass through the tube. Tube obstruction because of pa­tient bite was then suspected. Ventilation became very difficult, even using bag ventilation. Meanwhile, the satu­ration dropped to 80%. Propofol 1.5 mg.kg -1 was injected intravenously to deepen the anaesthesia. The armoured tube was removed and LMA size 4 classic was intro­duced as rescue ventilation [9],[10] . LMA was removed with patient awake. There were no further complications or sequelae. Later inspection of the spiral embedded tube showed that patient bite had deformed the spiral wire and led to complete and permanent occlusion of the tube and a barely visible internal meniscus in the tube was detected. [Figure 1]

   Discussion Top

Spiral embedded endotracheal tubes have a metal or nylon spiral wound reinforcing wire covered with both internally and externally by rubber, latex or PVC or sili­cone. The primary advantage of this framework is that these tubes are resistant to kinking and compression. This makes them useful in certain clinical conditions like head and neck surgeries, in neurosurgeries, surgeries in prone position, sitting posture and where head and neck positioning is required for better surgical access.

Despite several advantages, there are a number of problems associated with spiral embedded endotracheal tubes. The tube usually requires a stylet for insertion and there are chances that tube may rotate on the stylet during insertion. Nasotracheal intubation is difficult with armoured tubes. The elastic recoil force may increase the tendency to dislodge from the secured position; su­turing to the patient is often performed for this reason. Another practical problem with these tubes is that they cannot be shortened. Tube laceration as a result of bite can also lead to aspiration of the tube material. There are various reports of respiratory obstruction with spiral embedded tubes; all of the cases reported in relation to defective tubes occurred when tubes were submitted to repeated sterilizations [1],[4],[5] . Obstruction of an ETT by mucus, blood, or a kink is not uncommon, whereas ob­struction by a foreign body is a rare event [6] . During recovery from anaesthesia, biting on the flexometallic tube can result in permanent occlusion or narrowing of the lumen [7],[8] . Various foreign bodies [7],[8],[9],[10] and "biting down" on the spiral of a reinforced ETT [11] have been reported to cause obstruction. During recovery from anaesthe­sia, biting on the flexometallic tube can result in permanent occlusion or narrowing of the lumen [2],[4] , Some spiral embedded tubes have an external covering over the bite portion but in our case the tube did not have this protec­tion. Biting on the tube causes respiratory obstruction and may result in complications like hypoxia, hypercarbia, negative pressure pulmonary edema, rise in intracranial pressure and rise in blood pressure. Early recognition of the problem may avoid these dreaded complications. Increase in airway pressure, a positive deflection on the inspiratory phase of capnography and pulse oximeter desaturation pointed towards obstruction at some level which we anticipated and confirmed by inability to pass suction catheter though the spiral embedded tube.

Thus, early anticipation of obstruction of spiral embedded tube can prevent complications which may at times be fatal to the patient. So, spiral embedded endot­racheal tubes which are very useful in surgeries where position of the patient require mobility of head, and neck and acute angling of the tube for surgical access, may at times itself result in permanent occlusion or deformity of the tube resulting in complications. Moreover, laryngeal mask airway can be used as rescue ventilation [9],[10] as in our case armoured ETT was replaced by LMA.

   References Top

1.Catane R, DavidsonJT. Ahazard of cuffed flexometallic endot­racheal tubes. Br J Anaesth 1969;17:297.  Back to cited text no. 1      
2.Parmet JL, Colonna-Romano P, Horrow JC, et al. The laryn­geal mask airway reliably provides rescue ventilation in cases of unanticipated difficult tracheal intubation. Anesth Analg 1998 87:661.  Back to cited text no. 2  [PUBMED]  [FULLTEXT]  
3.Benumof JL. Laryngeal mask airway. Indications and contraindications. Anesthesiology 1992;77:843.  Back to cited text no. 3  [PUBMED]  [FULLTEXT]  
4.Populaire C, Robard S, Souron R. An armoured endotracheal tube obstruction in a child. Can J Anaesth 1989; 36:331-2.  Back to cited text no. 4  [PUBMED]    
5.Wright PJ, Mundy JV, Mansfield CJ. Obstruction of armoured tracheal tubes: case report and discussion. CanJAnaesth 1988; 35: 195-7.  Back to cited text no. 5      
6.Szekely SM, Webb RK, Williamson JA, Russell WJ. The Aus­tralian Incident Monitoring Study. Problems related to the en­dotracheal tube: an analysis of 2000 incident reports. Anaesth Intensive Care 1993; 21: 611-6.  Back to cited text no. 6  [PUBMED]    
7.P. Martens. Persistent narrowing of an armoured tube. Anaes­thesia 1992; 47:716-17.  Back to cited text no. 7      
8.Bruce D Spicers. Complete airway obstruction of armoured endotracheal tubes. Anesth Analg 1991; 73:95-6.  Back to cited text no. 8      
9.Hoffman CO, Swanson GA. Oral reinforced endotracheal tube crushed and perforated from biting .AnesthAnalg 1989;69:552-­553.  Back to cited text no. 9      
10.Eipe, et al. Neck contracture release and reinforced tracheal tube obstruction. Anesth Analg 2006; 102: 1911-1912.  Back to cited text no. 10      
11.Brusco L Jr, Weissman C. Pharyngeal obstruction of a rein­forced orotracheal tube. Anesth Analg 1993; 76: 653-4.  Back to cited text no. 11  [PUBMED]  [FULLTEXT]  


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