Real-time visualization of the gastrointestinal tract during nasogastric tube placement: Pilot study of new video-Assisted system

Abstract

Background and study aims

Nasogastric (NG) tubes are commonly inserted blindly, leading to complications. Existing NG tube placement-assisting systems face safety and cost-effectiveness issues. This study aimed to evaluate a new assisting system using a camera probe inserted into the NG tube to provide real-time visualization.

Patients and methods

Thirty patients requiring nasogastric tube placement were prospectively included. The primary objective was to determine the success rate of NG tube placement, while the secondary objectives included assessment of usability and safety of this system.

Results

Our findings revealed a high success rate of 96.7%. Median time to complete NG tube placement was 3.8 minutes. No serious complications were observed during the 7-day follow-up period. Operator feedback indicated this system helps facilitate NG tube placement, identify the gastric mucosa and safety landmark, and ease of camera wire removal. However, image visibility received a slightly lower score due to gastrointestinal secretions entering the NG tube through the side hole. To address this, air insufflation was used to enhance visibility in 13 patients.

Conclusions

The video-assisted system provides real-time visualization of the gastrointestinal tract during tube insertion and has been shown to enhance the safety and effectiveness of NG tube placement.

Graphical abstract

Keywords

Quality and logistical aspects - Quality management - Performance and complications - Endoscopy Upper GI Tract - Diagnosis and imaging (inc chromoendoscopy, NBI, iSCAN, FICE, CLE)

Introduction

Nasogastric (NG) tubes are commonly used in clinical practice, but blind insertion can lead to complications with an average malposition rate of 1.9% [1]. Various methods have been developed to confirm NG tubes position, with x-ray being the most accurate method, but it lacks real-time information and requires radiation [2]. Notably, the National Patient Safety Agency of the United Kingdom reported 21 deaths and 79 cases of injuries resulting from misplaced NG tubes between 2005 and 2010, with 45% of these incidents attributed to misinterpretation of x-ray results [3].

The CORTRAK2 enteral access system, which uses a reusable electromagnetic sensing device to guide NG tubes placement, had a reported assisted success rate of 82.6% to 85% [4] [5] [6]. However, the US Food and Drug Administration (FDA) recalled the product in 2022 due to safety concerns, including injuries and deaths [7]. Another Integrated Real-Time Imaging System (IRIS) incorporates a miniature video camera at its tip to enable real-time visualization during insertion, resulting in reported assisted success rates of 86% to 97.8% [8] [9] [10]. However, the higher cost of this technology limits its use.

We developed a video-assisted system for NG tube placement guidance, consisting of a cable with a mini camera that can be inserted into an NG tube. Our system combines the advantages of both CORTRAK2 and IRIS systems by providing real-time visualization during tube insertion and is potentially reusable. This study aimed to evaluate the efficacy of this system in ensuring proper NG tube placement.

Patients and methods

Study design and patient selection

This prospective study was conducted in an Intensive Care Unit (ICU) and Gastroenterology Ward in our hospital. Physicians selected and invited the patients, who were aged 20 years and older and required NG tubes for enteral feeding or decompression, to participate in this study. Informed consent was obtained before enrollment. Patients who could not undergo x-ray for tube position confirmation, those who were hemodynamically unstable (mean arterial pressure ≤ 65 mm Hg), and those with skull base fractures were excluded. This study was approved by the Institutional Review Board of our hospital (B-BR-111–006) and the Taiwan FDA (no. 1110601678) and registered on ClinicalTrials.gov (NCT05486286).

Design of video-assisted system for nasogastric tube placement

The video-assisted system comprised several components, as shown in [Fig. 1]. The three-way connector is attached to the rear end of the NG tube, allowing for camera probe insertion. If needed, one port of the three-way connector can be connected to an air inflator to improve visibility by introducing air into the NG tube ([Fig. 2]). The camera probe is then connected to the image processing box, which is connected to the image display for real-time viewing. The camera probe has the following technical specifications: resolution (400 × 400 pixels), field of view (120°), four light-emitting diodes for illumination, maximum diameter (3.0 mm), and wire diameter (2.1 mm).

Fig. 1 The video-assisted nasogastric (NG) tube placement assisting system. The components of this system include an image display facilitated by an Android phone, an image processing box, a camera probe, a three-way connector with its cap, and the NG tube itself.

Fig. 2 Setup of the 3-way connector. Illustration of the 3-way connector attached to the rear end of the NG tube, allowing for camera probe insertion and optional air insufflation to enhance visibility.

Feeding tube insertion and follow-up

This study used 15F feeding tubes with an outer diameter of 4.5 mm and an inner diameter of 3.5 mm (Freka, Bad Homburg, Germany). Patients were advised to maintain a nothing-by-mouth status for at least 4 hours. Patient position during NG tube insertion is sitting upright or semi-upright. If misplacement into the trachea was detected during NG tube placement, the feeding tube was withdrawn and reinserted into the stomach. A carbon dioxide (CO₂) insufflator (Olympus, Tokyo, Japan) was used whenever necessary to facilitate feeding tube placement or confirm its position [11]. After placing the NG tube, the position of the NG tube was reconfirmed by chest x-ray imaging for every patient. The operator completed the case report form and a questionnaire. The following variables were recorded: time to complete tube placement, time to visually confirm the stomach position, time to take x-ray, number of attempts, vocal cord/trachea visualization, need for air insufflation, patient level of consciousness, oxygen device (endotracheal tube or tracheostomy, with or without mechanical ventilation), sedation status, and purpose of tube placement. A study nurse monitored patient condition for the next 7 days and recorded any observed serious complications.

Outcome measurements and definitions

The primary outcome of this study was the technical success rate for placing the NG tube in the stomach using this video-assisted system, as confirmed by x-ray examination. This outcome serves as the main measure of the feasibility of the system. Secondary outcomes focused on assessing usability of the system. We designed a questionnaire to measure operator response using a Likert-type scale [12]: (1) This system helps facilitate NG tube placement; (2) This system helps identify the safety landmark (not entering the vocal cord/trachea); (3) This system helps identify the gastric mucosa; (4) This system provides good image visibility; and (5) Removing the camera probe is easy. The operator assessed usability of this video-assisted system to capture their subjective experience during the procedure.

Statistical analysis

Because this was a first-in-human pilot study, no sample size was calculated. Continuous variables are presented as means with standard deviations for normally distributed variables and as medians with interquartile ranges (IQRs) for skewed distributions. For categorical variables and outcomes, we calculated counts and percentages. If patients had missing data or loss of follow-up, they were excluded from the final analysis.

Results

This study enrolled 30 patients from August 2022 to May 2023, of whom 21 were admitted to the ICU. Mean age was 74.3 ± 13.6 years. Median Glasgow Coma Scale (GCS) score was E3/Vt/M5. Most patients had an endotracheal tube or tracheostomy (63.3%), indicating the need for respiratory support. More than half of the patients (53.3%) were mechanically ventilated ([Table 1]).

Table 1 Baseline characteristics of the 30 enrolled patients.

Baseline characteristics
E, eye opening; V, verbal response; M, motor response; T, tracheostomy; NG, nasogastric; SD, standard deviation.
Age (mean ± SD)	74.3 ± 13.6
Gender (male: female)	18: 12
Conscious level, median (Q1, Q3)
E (median, IQR)	3 (3, 4)
V (median)	T (T, 2)
M (median)	5 (4, 6)
Oxygen device, N (%)
No need for oxygen device	11 (36.7%)
Endotracheal tube	11 (36.7%)
Tracheostomy	8 (26.7%)
Indication for NG tube placement, N (%)
For nutrition support	29 (96.7%)
For gastrointestinal tract decompression	1 (3.3%)

Outcomes

The primary outcome of successful placement into the stomach was achieved in 29 patients (96.7%). In the first case, placement could not be achieved due to a tortuous lower third esophagus, and the NG tube was placed with the assistance of esophagogastroduodenoscopy. For all patients except this one, follow-up was completed and data were collected.

[Table 2] shows procedure results. Median time to complete tube placement was 3.8 minutes (IQR, 1.9–5.3). Median time to take an x-ray for position confirmation was 71 minutes (IQR, 44.5–151.5). Thirteen patients needed air insufflation during the procedure to improve visibility of the gastric mucosa. Four patients required a second NG tube placement attempt, and two underwent tracheal visualization. No serious complications were observed during 7-day post-procedure follow-up, such as aspiration pneumonia, pneumothorax, hollow organ perforation, or death.

Table 2 Nasogastric tube placement-related outcomes and technique information from the 30 enrolled patients.

	N (%) or median (IQR)
*Serious complications included aspiration pneumonia, pneumothorax, hollow organ perforation, and even mortality during the 7-day post-procedure follow-up. IQR, interquartile range.
Successful placement into the stomach	29 (96.7%)
Serious complications*	0
Technique information
Time for completing tube placement, minutes	3.8 (1.9–5.3)
Time to visual confirmation of stomach position, minutes	1.5 (0.9–3.1)
Time until taking X-ray, minutes	71 (44.5–151.5)
Deep of tube placement, cm	60 (60–65)
Need for air insufflation for position confirmation	13 (43.3%)
Patients requiring a second nasogastric insertion attempt	4 (13.3%)
Patients with visualization of the trachea	2 (6.7%)

As shown in [Table 3], the operators consistently rated the video-assisted system usability favorably (> 4 points) for all questions. However, the rating regarding image visibility was slightly lower (mean score: 4.0 points), although it still provided valuable insights. The most common problem was that oral secretions could interfere with the visual field, which required air insufflation in 13 patients to ensure clear visualization of the gastric mucosa.

Table 3 Operator Likert scale and mean scores.

Likert scale: from (1) strongly disagree to (5) strongly agree	Mean (ranges)
This system helps facilitate nasogastric tube placement	4.3 (4–5)
This system helps identify the safety landmark (not entering the vocal cord/trachea)	4.6 (3–5)
This system helps identify the gastric mucosa	4.8 (3–5)
This system provides good image visibility	4.0 (2–5)
Removing the camera probe is easy	4.7 (4–5)

Technical challenge

We trimmed the NG tube opaque tip in our initial case to improve visibility ([Fig. 3] a,b). However, this created an open end that allowed secretions from the nasal cavity or gastrointestinal tract to obstruct the visual field. In the subsequent 29 cases, we kept the tip of the NG tube untrimmed and positioned the camera probe between the tip and the side hole. Notably, the camera was not directly attached to the opaque tip, enabling the surroundings to be seen through the transparent tube wall ([Fig. 3] c-f, [Video 1]). However, saliva or other secretions could still enter the tube through the side hole. We occasionally had to perform repetitive back-and-forth movements of the camera wire to improve the visual field, which was inconvenient. This technical challenge warrants future attention and resolution.

Fig. 3 Various aspects of a trimmed and untrimmed nasogastric (NG) tube, along with images captured by the camera probe. a The trimmed tip of the NG tube. b Images obtained from the camera probe while employing the trimmed tip of the NG tube. c The untrimmed tip of the NG tube, with the camera probe inserted closely adjacent to the tip. d Images captured by the camera probe from the perspective of position c. e The untrimmed tip of the NG tube, with the camera probe inserted between the side hole and the tip. f Images obtained from the camera probe at the position of e.

With the NG tube placement assistance system, the camera can visualize the surrounding anatomy through the transparent tube wall, from entry into the nasal cavity through the oropharynx, hypopharynx, esophagus, esophagogastric junction, and into the stomach.Video 1

Discussion

We developed an NG tube placement-assisting system with a success rate of 96.7% in this pilot study. Operator feedback indicated the system was easy to use. Real-time visualization during NG tube placement prevented tracheal misplacement, thereby diminishing risk of complications such as aspiration pneumonia or pneumothorax. Furthermore, the simple external structure of the camera probe suggests the possibility of reuse following proper certification, making it potentially suitable for widespread application in real-world scenarios. In addition, median time to completing NG tube placement using this system was 3.8 minutes, which is comparable to or slightly shorter than previous reports about the IRIS system [8] [10] [13].

The traditional method of placing these tubes without visual guidance may result in misplacement and subsequent serious complications, such as aspiration pneumonia, pneumothorax, hollow organ perforation, and even death [14]. Although x-ray confirmation remains the gold standard, misinterpretation can still lead to adverse events [4]. Scientists and medical companies have been working on new inventions, such as CORTRAK2 or IRIS, to address this issue. CORTRAK2 used an alternative method by inserting an electromagnetic sensing cable into the NG tube to display its relative path and guide insertion [4] [5] [6]. One noteworthy advantage of this method is reusability of the sensing cable, which is compatible with standard feeding tubes. However, the device faced significant adverse outcomes related to misinterpretation of the position based on depiction of the tube form, leading to a recall by the US FDA in 2022 [7]. In contrast, IRIS used real-time imaging to guide insertion and demonstrated promising performance in various studies [8] [9] [10] [15]. However, its integration of the video camera at the NG tube tip resulted in high cost, limiting its widespread adoption, particularly under Taiwanese Public Health Insurance.

To address these challenges, we developed our video-assisted NG tube placement system that combines the advantages of both approaches: real-time imaging to guide insertion and potential reusability of the camera probe. Integration of the video camera at the NG tube tip in IRIS resulted in high costs and limited its widespread use. To reduce overall costs, our system consists of an image processing box and a camera probe, both of which are reusable. The camera probe may be more prone to breakage after repeated use, but it can be replaced separately, helping to minimize expenses. This design is intended to be cost-effective, particularly for high-risk patients. Although exact pricing is difficult to determine before market release and may vary by country, we estimate the system cost to be approximately USD 3,500, based on current conditions in Taiwan.

Nonetheless, our system faced challenges. Because this study used a commercial NG tube with a nontransparent tip, the camera probe must be placed a little distal to the side hole away from the tip end so that surrounding structures can be visualized through the transparent tube wall. Secretion bubbles from the NG side hole may affect the visual field, necessitating air insufflation, camera probe cleaning, or gastrointestinal content suctioning during NG tube insertion. This problem may be solved by further designing a dedicated NG tube. In addition, using an endoscopic CO₂ insufflator unit for air insufflation is inconvenient in clinical practice. Therefore, there is a need to develop more convenient methods, such as insufflator bulbs similar to those used in the IRIS system.

Limitations

This study has several limitations. First, due to its status as a first-in-human study, it featured a relatively small sample size and lacked comparative groups. Given the relatively low incidence of serious complications associated with NG insertion, this pilot study was not designed to assess the potential of the device to reduce complication rates. A larger-scale study is required to address this question, and to provide more robust and generalizable results. Second, there is a potential for selection bias, because both the patient/family and the physician may have had specific considerations for case enrollment involving a totally new device. This is reflected in the final cohort, in which the enrolled patients had relatively higher GSC scores. Third, this study used a relatively large-bore NG tube (15F) due to its standard use in our hospital, despite the fact that smaller-bore NG tubes are more comfortable for patients. To address this, we have developed and tested a second-generation camera probe in vitro that is compatible with 10F and 12F NG tubes. Finally, in real-world scenarios, NG tube placement is often performed by general physicians. However, all investigators in this study were gastroenterology specialists. Therefore, general physicians may have to learn to identify the esophageal and gastric mucosae from the trachea. Nevertheless, based on past reports about the IRIS system, there is reason to believe that all physicians could quickly learn to identify the correct anatomical structures.

Conclusions

In conclusion, the video-assisted NG tube placement system provides real-time visualization of the gastrointestinal tract during tube insertion. This capability enhances the success rate for confirming feeding tube placement, potentially minimizing severe complications. With ongoing design improvements, this method has the potential to evolve into a more practical approach.

Conflict of Interest

The authors declare that they have no conflict of interest.

Acknowledgement

The research was supported in part by the Ministry of Health and Welfare (MOHW 112-TDU-B-211-144003), the National Cheng Kung University Hospital (NCKUH-11204024), and National Science and Technology Council (NSTC 113-2314-B-006 -057-MY3).

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Publication History

Received: 30 August 2024

Accepted after revision: 21 November 2024

Accepted Manuscript online:
02 December 2024

Article published online:
13 January 2025