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 staybeta, 0.471; P = .020; extubation timebeta 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.