We report the case of a woman undergoing general anaesthesia in whom a gastric tube became knotted within her stomach. This is a relatively unusual phenomenon, particularly when the gastric tube is used in conjunction with a supraglottic airway device. This poses a risk to patient safety. We highlight the relevant risk factors for gastric tube knotting, and suggest management options both to reduce this risk and to safely manage the patient in whom the gastric tube has become knotted.

• Gastric tube

• Airway

• Safety

• Knotting

• Supraglottic airway device

Rookes C, Dimber R, Belliappa U (2024) Don’t Get It Twisted: Self-knotting Gastric Tube used with a Supraglottic Airway Device. Int J Clin Anesthesiol 12(1): 1129.

We report the case of a woman in whom a gastric tube became knotted and stuck in the stomach, having been inserted via the port in the supraglottic airway device under general anaesthesia. She was undergoing elective upper gastrointestinal surgery and was generally well. This is an unusual phenomenon, particularly in the context of elective surgery using a supraglottic airway device. It also carries risk to the patient, both in terms of a lack of gastric decompression and subsequent risk of regurgitation and aspiration in an unprotected airway, as well as the potential for injury on attempts to forcibly remove the gastric tube (including inadvertent removal of the airway device).

A 43-year old female underwent an elective open repair of an umbilical hernia. She had a history of gastritis and gastrooesophageal reflux, which was treated in the community with a PPI. She underwent general anaesthesia, and a supraglottic airway device (iGel™ size 4) was used. A gastric tube was inserted to a length of 70 cm to reduce the risk of aspiration of gastric contents. The case proceeded uneventfully. Spontaneous ventilation was re-established via the iGel™ and she was taken to recovery.

In recovery, attempts were made unsuccessfully to aspirate the NGT prior to its removal. The recovery nurses also found that the gastric tube was impossible to remove from the iGel port. The patient subsequently regained consciousness, and the iGel™ and gastric tube were removed en bloc. We discovered that the distal end of the gastric tube had irrevocably knotted, thus explaining the above (Figures 1,2).

Figure 1: Removed iGelTM with knotted gastric tube.

Figure 2: Re-enactment for picture quality.

No harm came to the patient as a result, and no changes in her observations nor clinical features were seen.

Gastric tubes are used intraoperatively in a wide range of scenarios. In the elective surgical context, gastric tubes have a role in reducing the risk of aspiration of gastric contents in patients (such as ours) with evidence of gastro-oesophageal reflux disease or lower oesophageal sphincter laxity. This permits the use of supraglottic airways in such patients, in whom endotracheal intubation and the use of neuromuscular blocking agents would be otherwise mandated.

The knotting of an intragastric gastric tube is an unusual example of equipment failure which can not only pose a risk to the patient, but also cause confusion in the treating team due to its infrequency. On review of existing literature, there are a small number of case reports relating to knotted gastric tubes when inserted nasally or orally, and only one reported case of gastric tube knotting when used with a supraglottic airway device [1].

Ravind R, et al. [2] lists a number of factors increasing the risk of intragastric knotting of a gastric tube - although their paper discusses nasogastric tubes, some of these can be related to our case involving the use of a supraglottic airway device. In terms of immediately modifiable risk factors (i.e. those relating to insertion technique and patient selection) include excessive length of insertion and repetitive attempts at insertion [2], as well as patients with a history of abdominal surgery or irregular intraabdominal anatomy [2]. Other risk factors included narrow-bore tubes with softer materials [2] - however, the comparative risk posed by these factors is unclear. It should be noted that both fine-bore feeding tubes and larger bore Ryles tubes have both been reported to have knotted whilst in use [3,4].

We have determined the following learning points from this case:

1. Don’t insert the gastric tube more than 5cm beyond the gastro-oesophageal junction. Before insertion, measure an appropriate distance using the following landmarks - nostril, tragus, xiphisternum.

2. There is a risk of airway removal if a knotted gastric tube is forcibly removed, as well as trauma to tissues. If the gastric tube is not aspirating and not easy to remove, consider knotting and leave it in situ until the patient is fully awake, and remove en bloc.

3. A supraglottic airway device with gastric tube is not always a safe option for patients with high gastric aspirates.

This case report was published with the written consent of the patient.

1. Garg S, Kapoor MC. Self-knotting of a gastric tube passed through i-gel™. Indian J Anaesth. 2015; 59 : 331-332.

2. Ravind R, Prameela CG, Gurram BC, Dinesh M. Naughty knot: A case of nasogastric tube knotting. BMJ Case Rep. 2015; 2015: bcr2015209937.

3. De U, Agarwal A, Singh V. Spontaneous knotting of ryles tube in a post operative patient. Pakistan Journal Of Medical Sciences. 2007; 23: 641.

4. Mohsin M, Saleem Mir I, Hanief Beg M, Nazir Shah N, Arjumand Farooq S, Altaf Bachh A, et al. Nasogastric tube knotting with tracheoesophageal fistula - A rare association. Interact Cardiovasc Thorac Surg. 2007; 6: 508-510