Description

Objective: To evaluate the effectiveness of ultrasound Doppler in determining the correct placement of gastric feeding tubes (GFTs) in intensive care patients compared to the standard of care, chest X-ray (CXR).

Study Design: A diagnostic study involving ICU patients who require GFT placement or replacement.

Background: Misplacement of GFTs is a common complication in ICU settings, with significant potential consequences for patient safety. Ultrasound Doppler has emerged as a potential alternative to CXR for confirming GFT placement due to its portability, ease of use, and real-time assessment.

Methods

Subject Selection: Subjects will be recruited from the ICU at the Leiden University Medical Center (LUMC) who meet the inclusion criteria: tracheally intubated, require GFT placement or replacement, and provide informed consent.

Ultrasound Procedure: At the esophageal and gastric levels, ultrasound will be performed using a Philips Lumify® S4-1 broad band sector array transducer. An antrum Doppler window will be set to visualize the "mosaic sign," a characteristic Doppler signal indicative of correct GFT placement.

Image Acquisition and Coding: During ultrasound, 20 ml of air will be injected through the GFT, and images will be captured. These images will be anonymized and labeled with the depth at which the insufflation occurred (20 cm or 50 cm) or the location of the insufflation (tracheal suction catheter).

Ultrasound Interpretation: An intensivist expert in ultrasound will blind to the original localization of the GFT analyze the anonymized images. The intensivist will classify each image as having a "mosaic sign present" or "mosaic sign absent."

Correlation with CXR: The ultrasound interpretation will be compared to the gold standard of CXR to determine the sensitivity and specificity of ultrasound Doppler.

Secondary Objectives:

• Investigate the correlation between false positive and false negative results and patient characteristics such as gender, BMI, positive end-expiratory pressure (PEEP), tidal volume, and presence of abdominal gas in CXR.
• Assess the safety of ultrasound Doppler in terms of adverse events (AEs) and serious adverse events (SAEs).

Sample Size: A sample size of 58 patients is expected to provide sufficient power to detect statistically significant differences in sensitivity and specificity between ultrasound Doppler and CXR.

Ethical Considerations:

Ethical Approval: The study protocol has been approved by the Leiden University Medical Center Ethical Review Board (LUMC-ERB).

Informed Consent: All participants will provide informed consent prior to undergoing ultrasound Doppler and CXR.

Safety Monitoring: Adverse events will be monitored and reported as per the regulations of the LUMC and the Medical Research Involving Human Subjects Act (WMO).

Administrative Aspects:

Data Collection and Storage: Patient and clinical data, including anonymized ultrasound images and CXRs, will be collected and stored using the Castor cloud-based clinical data management system.

Monitoring: The study will be monitored by internal monitors of the Leiden University Medical Center (LUMC).

Reporting: Annual progress reports will be submitted to the accredited METC, and the final study report will be submitted upon completion of the study.

Expected Findings:

Ultrasound Doppler is expected to demonstrate high sensitivity and specificity in determining the correct placement of GFTs in ICU patients compared to CXR.

Potential correlation between false positive and false negative results with certain patient characteristics, such as gender, BMI, and presence of abdominal gas in CXR, may be identified.

The safety profile of ultrasound Doppler is expected to be favorable with minimal AEs and no SAEs.

Conclusion: This study aims to evaluate the efficacy of ultrasound Doppler in determining the correct placement of GFTs in ICU patients. The findings of this study will contribute to the development of non-invasive methods for confirming GFT placement, potentially improving patient safety and reducing the need for CXRs.