Diagnostic role of abdominal ultrasound (point-of-care ultrasonography) in confirming nasogastric tube position: a living systematic review

Purpose: The primary objective of this research is to evaluate the diagnostic accuracy of ultrasonography as a bedside tool for confirming the correct placement of nasogastric and orogastric tubes in clinical practice. While chest radiography remains the "gold standard," it involves exposure to ionizing radiation, creates delays in starting nutrition or medication, and increases healthcare costs. This project seeks to synthesize the available evidence to determine if abdominal and cervical ultrasound can safely and accurately replace or complement radiography. Given the rapid emergence of new studies in the field of Point-of-Care Ultrasound (POCUS), this study is designed as a Living Systematic Review. This methodology ensures that the findings are updated every six months, maintaining the clinical relevance and currency of the evidence for decision-making in emergency and critical care settings. Methodology Overview: Following the PRISMA guidelines and Cochrane methodology, we will include observational studies (prospective cohorts, cross-sectional, and case-control) that compare ultrasonography against radiography. The risk of bias will be assessed using the QUADAS-2 tool, and the certainty of the evidence will be evaluated using the GRADE approach. We will utilize bivariate random-effects models for the meta-analysis to account for the inherent correlation between sensitivity and specificity. Expected Outcomes: Diagnostic Accuracy Metrics: We expect to define a pooled sensitivity and specificity for ultrasound. Based on previous evidence, we anticipate a specificity near 100%, which is critical for preventing pulmonary aspiration. Safety and Efficiency: We aim to demonstrate that ultrasound significantly reduces the "time-to-confirmation" compared to X-rays, facilitating faster clinical interventions. Subgroup Insights: The review expects to identify factors that influence accuracy, such as the anatomical "acoustic window" (cervical vs. abdominal), the use of dynamic techniques (air/saline bolus), and patient characteristics (BMI and sedation status). Living Evidence Map: A major outcome will be a continuously updated evidence synthesis that provides clinicians with a reliable, evidence-based protocol for the bedside use of ultrasound in gastric tube verification.