title: Predictors of respiratory instability in neonates undergoing patient ductus arteriosus ligation after the introduction of targeted milrinone treatment.
abstract: The postoperative course of preterm babies undergoing surgical closure of a patent ductus arteriosus (PDA) is often complicated by postligation cardiac syndrome (PLCS). Despite targeted milrinone prophylaxis, some infants continue to experience postoperative respiratory deterioration. Our objective is to describe the immediate postoperative course and identify risk factors for respiratory instability when preterm infants undergoing PDA ligation are managed with targeted milrinone treatment.
  
  
  
  A retrospective review of a cohort of infants undergoing PDA ligation between January, 2010 and August, 2013 was conducted. All infants had a targeted neonatal echocardiogram performed 1 hour after surgery. Infants received prophylactic milrinone treatment if the left ventricular output was <200 mL/kg/min. The primary outcome measure was the development of respiratory instability within 24 hours of surgery. Multivariable logistic regression was performed to identify predictors of respiratory instability.
  
  
  
  Eighty-six infants with a median gestational age of 25 weeks (interquartile range [IQR], 24-26) and a birth weight of 740 g (IQR, 640-853) were included in this study. Forty-nine (57.0%) received milrinone prophylaxis. There were 44 (51.2%) infants who developed oxygenation or ventilation failure, and 7 (8.1%) neonates developed PLCS. Infants with longer isovolumic relaxation time (IVRT ≥30 milliseconds) were more likely to develop either oxygenation or ventilation failure.
  
  
  
  Although the incidence of PLCS has declined after the introduction of targeted milrinone prophylaxis, many preterm infants continue to develop respiratory instability after surgical ligation. In this population, diastolic dysfunction manifested by prolonged IVRT could be associated with an adverse postoperative respiratory course.
authors.affiliation: Department of Pediatrics, University of British Columbia, Vancouver, Canada.
authors.forename: Joseph Y
authors.initials: JY
authors.lastname: Ting
authors.affiliation: Department of Pediatrics, University of Toronto, Toronto, Canada.
authors.forename: Maura
authors.initials: M
authors.lastname: Resende
authors.affiliation: Department of Pediatrics, University of Toronto, Toronto, Canada.
authors.forename: Kiran
authors.initials: K
authors.lastname: More
authors.affiliation: Department of Pediatrics, University of Toronto, Toronto, Canada.
authors.forename: Donna
authors.initials: D
authors.lastname: Nicholls
authors.affiliation: Department of Pediatrics, University of Toronto, Toronto, Canada.
authors.forename: Dany E
authors.initials: DE
authors.lastname: Weisz
authors.affiliation: Department of Neonatology, The Rotunda Hospital, Dublin, Ireland; Department of Paediatrics, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Afif
authors.initials: A
authors.lastname: El-Khuffash
authors.affiliation: Department of Pediatrics, University of Toronto, Toronto, Canada; Department of Physiology, University of Toronto, Toronto, Canada.
authors.forename: Amish
authors.initials: A
authors.lastname: Jain
authors.affiliation: Department of Pediatrics, University of Toronto, Toronto, Canada; Department of Physiology, University of Toronto, Toronto, Canada; Physiology & Experimental Medicine Program, The Hospital for Sick Children, Toronto, Canada. Electronic address: patrick.mcnamara@sickkids.ca.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: McNamara
mesh_terms: D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D016009:Chi-Square Distribution; D004374:Ductus Arteriosus, Patent / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D015150:Echocardiography, Doppler; D005865:Gestational Age; D006801:Humans; D062071:Infant, Extremely Premature; D007231:Infant, Newborn; D008026:Ligation; D016015:Logistic Models; D008168:Lung / Q000187:drug effects* / Q000503:physiopathology; D020105:Milrinone / Q000008:administration & dosage* / Q000009:adverse effects; D015999:Multivariate Analysis; D058987:Phosphodiesterase 3 Inhibitors / Q000008:administration & dosage* / Q000009:adverse effects; D012119:Respiration / Q000187:drug effects*; D012131:Respiratory Insufficiency / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D058987:Phosphodiesterase 3 Inhibitors; D020105:Milrinone
keywords: milrinone; neonates; oxygenation failure; patent ductus arteriosus; ventilation failure