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.