The definition of a haemodynamic significant duct in randomized controlled trials: a systematic literature review

Aim: A patent ductus arteriosus (PDA) is associated with morbidity in preterm infants. Treatment is prescribed for a haemodynamically significant duct (HSDA), but its definition varies. We systematically reviewed the clinical and ultrasound criteria used for the definition of an HSDA. Methods: PubMed and the Cochrane library were searched for randomized trials evaluating ductal treatment. The included studies were explored, and we categorized clinical and ultrasound criteria used to define an HSDA. Results: Sixty-seven trials were included in our review. Forty-two were placebo-controlled trials, and 25 were comparative trials. The diagnosis of the PDA was made by clinical examination, followed by ultrasound in most trials. Most trials used clinical and ultrasound criteria to define an HSDA, but there was a wide variety in criteria and cut-offs used. Of the clinical criteria, a murmur or hyperdynamic circulation was most used, and of the ultrasound criteria, the left-atrium-to-aorta ratio (LA/Ao ratio) was most used. Conclusion: We found a wide variety in the definition of an HSDA. This finding implies that comparison of studies is difficult. International consensus should be reached on the definition of an HSDA, which will make future studies more comparable.