title: Accuracy of the transpulmonary ultrasound dilution method for detection of small anatomic shunts.
abstract: The purpose of this study was to investigate the qualitative and quantitative accuracy of transpulmonary ultrasound dilution (UD) (COstatus™, Transonic Systems) for the detection of small anatomic shunts. It was a prospective, observational study in a multi-disciplinary pediatric intensive care unit. Seventy-three critically ill children (67 post cardiac surgery), with a median (IQR) age of 10 (3-50.3) months and a median (IQR) weight of 8 (3.43-13) kg were enrolled. Ultrasound dilution (UD) measurements were performed on patients within 1 h of undergoing two-dimensional echocardiography, which was used as the comparator technique. Shunt was diagnosed by characteristic changes on the UD curve shape, and was considered "test-positive" only if two or more measurements suggested the presence of the shunt. The UD technology also provided an estimate of pulmonary to systemic blood flow ratio (Qp:Qs). 12/73 (16.4 %) patients had a shunt identified by both UD and echocardiography. The overall accuracy (95 % CI) was 86.1 % (75.6-96.6 %), with a sensitivity of 85.7 % (57.2-98.2 %) and specificity of 86.4 % (75.0-94.0 %). The estimated Qp:Qs ranged from 0.7 to 1.4, which was consistent qualitatively with the echocardiographic findings on color flow doppler. Shunt was detected by UD alone in eight children; six of these had clinical conditions known to compromise dilution curve analysis (valve regurgitation, asymmetric pulmonary blood flow). Shunt was detected by echocardiography alone in two children; in both cases the shunt was tiny. UD is an accurate method for the detection of small anatomical shunts, both qualitatively and quantitatively.
authors.affiliation: Paediatric Intensive Care Unit, Evelina London Children's Hospital, Guy's and St Thomas' NHS Foundation Trust, Westminster Bridge Road, London, SE1 7EH, UK, rohitlibran2002@doctors.org.uk.
authors.forename: R
authors.initials: R
authors.lastname: Saxena
authors.forename: N
authors.initials: N
authors.lastname: Krivitski
authors.forename: K
authors.initials: K
authors.lastname: Peacock
authors.forename: A
authors.initials: A
authors.lastname: Durward
authors.forename: J M
authors.initials: JM
authors.lastname: Simpson
authors.forename: S M
authors.initials: SM
authors.lastname: Tibby
mesh_terms: D001783:Blood Flow Velocity; D002302:Cardiac Output / Q000502:physiology; D002405:Catheterization, Central Venous; D002675:Child, Preschool; D016638:Critical Illness; D015150:Echocardiography, Doppler; D005260:Female; D006344:Heart Septal Defects, Atrial / Q000000981:diagnostic imaging* / Q000601:surgery; D006439:Hemodynamics; D006801:Humans; D007223:Infant; D015278:Intensive Care Units, Pediatric; D008168:Lung / Q000098:blood supply / Q000000981:diagnostic imaging*; D008297:Male; D011446:Prospective Studies; D015203:Reproducibility of Results