Ultrasound-guided Bedside Placement of Nasojejunal Feeding Tubes for Critically Ill Patients

Summary

Bedside ultrasound-guided nasojejunal tube placement enables real-time visualization of the catheter trajectory and supports confirmation of post-pyloric positioning in the duodenum or jejunum.

Abstract

In critically ill patients, postpyloric feeding via a nasojejunal (NJ) tube is essential for those at high risk of aspiration. However, traditional blind insertion techniques are associated with high failure rates and complications. This study aims to establish a standardized, bedside ultrasound-guided protocol for NJ tube placement to enhance safety and efficacy. The procedure involves real-time tracking of the NJ tube from the esophagus to the jejunum using both linear and curvilinear probes. Key technical steps include pre-procedural assessment of the gastric antral area and motility, cervical verification, and dynamic guidance through the pylorus. The protocol identifies specific sonographic markers for confirmation: the 'Double-Track Sign' serves as the static indicator of tube presence in the gastrointestinal tract, while the dynamic ‘Cloud Sign’ confirms tube patency and tip location. Real-time visualization enables immediate correction of complications, such as pharyngeal coiling or tracheal deviation. The method facilitates passage through the pylorus by synchronizing advancement with peristalsis. Ultrasound-guided NJ tube placement provides a bedside, radiation-free approach for visualizing tube trajectory and identifying malposition during the procedure. This protocol article presents representative sonographic findings during NJ tube progression; comparative outcomes such as first-attempt success rate, procedure time, and adverse event rates were not evaluated.

Introduction

Enteral nutrition (EN) is widely recognized as the preferred route for nutritional support in critically ill patients, offering significant advantages over parenteral nutrition by preserving gut mucosal integrity, modulating the immune response, and reducing infectious complications¹. For patients at high risk of aspiration or those with severe gastric intolerance, post-pyloric feeding via NJ tube is often indicated to ensure safe and effective nutrient delivery². However, the bedside placement of NJ tube remains a formidable clinical challenge. Traditional blind insertion techniques are associated with high failure rates, frequent coiling within the stomach, and a substantial risk of inadvertent tracheobronchial misplacement, often necessitating multiple attempts that delay the initiation of critical nutrition³.

While fluoroscopy and endoscopy serve as gold standards for guiding tube placement, their utility in the intensive care unit (ICU) is limited by logistical constraints, including the need for patient transport, radiation exposure, high costs, and the requirement for specialized personnel⁴. Consequently, there is an urgent need for a safe, real-time, and radiation-free alternative that can be performed directly at the bedside, especially in low-resource settings.

Bedside ultrasound (US) has emerged as a promising 'visual stethoscope' for gastrointestinal assessment, increasingly utilized to evaluate gastric residual volume and antral motility⁵. Previous studies have extended its application to guide NJ tube insertion, allowing clinicians to visualize the tube's trajectory through the esophagus, stomach, and pylorus in real-time without ionizing radiation⁶. Correlational research suggests that US-guided techniques may improve first-attempt success rates and reduce procedure time compared to blind methods^3,7. This study aims to illustrate a comprehensive protocol for standardized, ultrasound-guided nasojejunal tube placement, highlighting critical technical considerations and serving as a reference for both clinical practice and medical education.

Protocol

All procedures involving human participants adhered to institutional ethical standards and the Declaration of Helsinki. This study was approved by the Ethics Committee of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine (Approval No.: 2026-2151). Written informed consent was obtained from the legally authorized representative for publication of the case report and accompanying images. This procedure is associated with potential risks, including aspiration, airway displacement, gastrointestinal injury, and other clinically significant complications.

1. Infection control and personnel

1. Perform hand hygiene and use standard precautions. Wear nitrile or latex-free gloves.
2. Use sterile, single-use ultrasound gel packets if the patient has open surgical wounds or compromised skin integrity near the scanning site.
3. Ensure that two clinicians are available for the procedure. Assign one clinician trained in critical care ultrasound to operate the probe and interpret images, and assign the second clinician to manipulate the feeding tube.
4. Maintain continuous communication between the ultrasound operator and the clinician manipulating the feeding tube throughout the procedure.

2. Equipment and machine settings

1. Select a linear array probe of 5–13 MHz for superficial structures, including the cervical esophagus and thyroid level.
2. Select a curvilinear array probe of 2–5 MHz for deeper abdominal structures, including the gastric antrum, pylorus, duodenum, and jejunum.
3. Adjust the image depth so that the target organ occupies the central two-thirds of the screen. Use a depth of approximately 3–6 cm for the neck and 10–15 cm for the abdomen.
4. Optimize the gain to distinguish the tube lumen from surrounding tissues. Avoid excessive gain that creates artifacts.
5. Position the focal zone at the depth of the target structure.
6. Prepare an NJ tube of appropriate length and diameter.
7. Prepare a 50 mL syringe and warm sterile water.

3. Patient preparation and positioning

1. Confirm that the patient has an indication for NJ tube placement, such as high risk of aspiration, gastroparesis, traumatic brain injury, or swallowing dysfunction.
2. Exclude contraindications, including active upper gastrointestinal bleeding, severe pyloric edema, paralytic ileus, hemodynamic shock, suspected bowel perforation, or intestinal necrosis.
3. Ensure that the patient has remained NPO for 6–8 h before the procedure.
4. Administer prokinetic agents 30 min before insertion if they are not contraindicated.
5. Perform gastric decompression through an existing nasogastric tube before NJ tube insertion if gastric air or contents obscure visualization.
6. Position the patient supine or with the head of the bed elevated to 30° for cervical scanning. Slightly extend the neck to expose the anterior neck.
7. Position the patient supine or with the head of the bed elevated to 30° for gastric scanning.
8. Place the patient in the right lateral decubitus position for pyloric or duodenal scanning to facilitate gastric emptying and align the pylorus with the probe window.

4. Assessment of gastric antral area and motility

1. Place the curvilinear probe in the epigastrium, longitudinal to the midline, with the indicator pointing toward the patient’s head.
2. Identify the left lobe of the liver and the abdominal aorta. Locate the gastric antrum as a ring-like structure between these landmarks.
3. Measure the gastric antral cross-sectional area (CSA) by manually tracing the antral perimeter on the ultrasound screen. Use the system’s built-in software to calculate the area.
4. Measure the anteroposterior (AP) and craniocaudal (CC) diameters of the gastric antrum for the dual-diameter method.
5. Calculate the CSA as follows, assuming an elliptical geometry:
   CSA = (π × AP × CC) / 4
6. Evaluate gastric antral motility in the semi-recumbent position after ingestion of 300 mL of warm water, if clinically appropriate.
7. Calculate the antral contraction frequency (ACF) by dividing the total number of contractions observed in 6 min by 3.
8. Calculate the antral contraction amplitude (ACA) as follows:
   ACA = (CSA max − CSA min) / CSA max
   Where CSA max and CSA min represent the antral areas during relaxation and contraction, respectively.
9. Calculate the motility index (MI) as follows:
   MI = ACF × ACA
10. Classify gastric motor function according to the MI threshold: normal motility, MI > 0.8; hypomotility, 0.4 < MI < 0.8; and gastric motor failure, MI < 0.4.
    NOTE: Gastric antral area correlates with gastric volume and may be used to estimate gastric residual volume and assess antral motility in critically ill patients.

5. Insertion into the esophagus

1. Advance the NJ tube gently through the nostril to a depth of 20–25 cm.
2. Place the linear probe transversely at the level of the thyroid gland.
3. Identify the triangular structure formed by the trachea, esophagus, and carotid artery.
4. Look for the Double-Track Sign within the esophageal lumen to confirm the presence of the NJ tube.
5. Withdraw and reattempt placement if the tube appears to advance and then retract on ultrasound, as this finding may indicate pharyngeal coiling.
   NOTE: The Double-Track Sign appears as two parallel hyperechoic lines on ultrasound. Failure to visualize the NJ tube within the esophagus, combined with an advancing-and-retracting motion of the catheter without luminal entry, indicates extra-esophageal placement and requires immediate repositioning.

6. Advancement into the stomach

1. Advance the NJ tube to a depth of 50–60 cm.
2. Place the curvilinear probe in the subxiphoid region in a longitudinal orientation. Identify the gastric antrum using the liver and aorta as landmarks.
3. Rotate the curvilinear probe to a transverse orientation in the subxiphoid region.
4. Visualize the Double-Track Sign moving within the gastric lumen as the static sign of tube placement.
5. Confirm intragastric tube position before injecting any liquid through the NJ tube.
   CAUTION: Do not instill warm water, saline, or any other liquid through the NJ tube unless proper placement of the tube within the gastrointestinal tract has first been verified. If the tube position remains uncertain, obtain bedside abdominal radiography before instilling liquid or proceeding further.
6. After confirming intragastric tube position, inject 40 mL of warm water followed by 10 mL of air.
7. Observe the Cloud Sign as a turbulent hyperechoic contrast emanating from the tube tip within the stomach.
   NOTE: In the epigastric view, the gastric antrum is identified near the left lobe of the liver and the abdominal aorta. The antrum appears as a ring-like structure within the angle formed by these two anatomical landmarks.

7. Passage through the pylorus into the duodenum

1. Advance the NJ tube to a depth of 70–90 cm.
2. Place the patient in the right lateral decubitus position.
3. Move the curvilinear probe to the right subcostal area.
4. Wait for spontaneous pyloric opening.
5. After confirming that the tube is positioned within the stomach, inject 50 mL of warm water if needed to facilitate pyloric opening according to institutional practice.
6. Gently advance the tube when the pyloric channel opens. Use a decrease in resistance or a “give” sensation as a tactile sign of passage.
7. Identify the Double-Track Sign in the horizontal duodenum as the static sign of successful NJ tube passage.
8. After confirming intraluminal tube position, inject warm water and observe the Cloud Sign moving from the antrum through the pylorus into the duodenum.

8. Final positioning in the jejunum

1. Advance the NJ tube to a depth of 95–105 cm.
2. Scan the periumbilical region.
3. Identify the Double-Track Sign in a mobile small bowel loop away from the gastric anatomy.
4. Differentiate the jejunum from the duodenum by identifying prominent valvulae conniventes, when visible.
   NOTE: Valvulae conniventes may be less distinct in critically ill patients. In this setting, use the absence of gastric anatomy and the presence of the Double-Track Sign in a mobile small bowel loop to support jejunal localization.

9. Postprocedure verification

1. Secure the NJ tube at the nostril once the tube is believed to be in the jejunum.
2. Obtain a final static ultrasound image of the NJ tube in the target location with the Double-Track Sign clearly visible.
3. Document the depth of insertion, ultrasound views obtained, and confirmation signs.
4. Initiate feeding only after definitive confirmation of post-pyloric placement.
   NOTE: Although ultrasound provides real-time confirmation, obtain a plain abdominal radiograph for final verification before initiating feeding when required by institutional policy.

Results

These ultrasound images were acquired at the Emergency Intensive Care Unit (EICU) of Sir Run Run Shaw Hospital during NJ tube placement performed by intensivists. Imaging was conducted by sonographers using a Mindray M9 ultrasound system. The surface landmark image was obtained from a standardized patient, while the sonographic images were captured from patients undergoing actual NJ tube placement. The procedure described is the total ultrasound-guided NJ tube placement technique. Figure 1 i...

Discussion

The establishment of reliable post-pyloric enteral access is a cornerstone of nutritional support for critically ill patients, particularly those at high risk of aspiration or suffering from gastric intolerance^8,9. While fluoroscopy and endoscopy remain the gold standards for NJ tube placement, their utility is often constrained by logistical barriers, radiation exposure, cost, and the need for specialized personnel transport^1,<...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Nasojejunal tube	Zhejiang Jiancheng Medical Technology Co., Ltd.	20152140103	12 Fr
Syringe	Zhejiang Longde Pharmaceutical Co., Ltd.	20193141951	38TWSB
Ultrasound gel	Hangzhou Kaipule Medical Devices Co., Ltd.	20150031	KL-250 Type II
Ultrasound probes	Shenzhen Mindray Bio-Medical Electronics Co., Ltd.	120-018844-00	C5-1s and L12-4s
Ultrasound system	Shenzhen Mindray Bio-Medical Electronics Co., Ltd.	20193061691	M9