Prognostic Value of a New Lung Ultrasound Score to Predict Intensive Care Unit Stay in Pediatric Cardiac Surgery

Background: Lung ultrasound (LUS) in pediatric cardiac surgery is gaining consensus. We (1) evaluated the prognostic value of a new LUS-score in pediatric cardiac surgery, and (2) compared LUS-score to conventional risk factors including age, The Society of Thoracic Surgeons/European Association of Cardio-Thoracic Surgery (STAT) score, cardiopulmonary bypass time, and prognostic biomarkers including brain natriuretic peptide and cystatin-C. Methods: LUS examinations were performed in 237 children (median age, 0.55 years; interquartile range, 0.09-4.15 years) at 12 to 36 hours after surgery. For each hemithorax, 3 areas (anterior/lateral/posterior) were evaluated in the upper and lower halves, constituting 12 total scanning areas. For each site a score was assigned: 0 (rare B lines), 1 (separated B lines), 2 (coalescent B lines), 3 (loss of aeration), and total LUS score was calculated as sum of all sites. The primary endpoints were intensive care unit length of stay and extubation time. Results: The mean total LUS score was 12.88 ± 6.41 (range, 0-26) and was higher in newborns (16.77 ± 5.25) compared with older children (5.36 ± 5.57; P < .001). On univariate analysis, LUS score was associated inversely with age (beta 0.26; P = .004) and body surface area (beta 3.41 P = .006) and positively with brain natriuretic peptide (beta 1.65; P < .001) and cystatin-C (beta 2.41; P < .001). The LUS score, when added as continuous predictor to a conventional risk model (age, STAT score, and cardiopulmonary bypass time) emerged significant both for intensive care unit length of stay (beta 0.145, P = .047) and extubation time (beta 1.644; P = .024). When single quadrants were analyzed, only anterior LUS score was significant (intensive care unit length of stay beta, 0.471; P = .020; extubation time beta 5.530; P = .007). Conclusions: Our data show the prognostic incremental value of a new LUS score over traditional risk factors in pediatric cardiac surgery.