title: Higher pulmonary dead space may predict prolonged mechanical ventilation after cardiac surgery.
abstract: Children undergoing congenital heart surgery are at risk for prolonged mechanical ventilation and length of hospital stay. We investigated the prognostic value of pulmonary dead space fraction as a non-invasive, physiologic marker in this population. In a prospective, cross-sectional study, we measured pulmonary dead space fraction in 52 intubated, pediatric patients within 24 hr postoperative from congenital heart surgery. Measurements were obtained with a bedside, non-invasive cardiac output (NICO) monitor (Respironics Novametrix, Inc., Wallingford, CT). Median pulmonary dead space fraction was 0.46 (25-75% IQR 0.34-0.55). Pulmonary dead space fraction significantly correlated with duration of mechanical ventilation and length of hospital stay in the entire cohort (r(s) = 0.51, P = 0.0002; r(s) = 0.51, P = 0.0002) and in the subset of patients without residual intracardiac shunting (r(s) = 0.45, P = 0.008; r(s) = 0.49, P = 0.004). In a multivariable logistic regression model, pulmonary dead space fraction remained an independent predictor for prolonged mechanical ventilation in the presence of cardiopulmonary bypass time and ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen (OR 2.2; 95% CI 1.14-4.38; P = 0.02). The area under the receiver operator characteristic curve for this model was 0.91. Elevated pulmonary dead space fraction is associated with prolonged mechanical ventilation and hospital stay in pediatric patients who undergo surgery for congenital heart disease and has additive predictive value in identifying those at risk for longer duration of mechanical ventilation. Pulmonary dead space may be a useful prognostic tool for clinicians in patients who undergo congenital heart surgery.
authors.affiliation: Division of Pediatric Pulmonary Medicine, University of California, San Francisco Children's Hospital, San Francisco, California 94143-0632, USA. ongt@peds.ucsf.edu
authors.forename: Thida
authors.initials: T
authors.lastname: Ong
authors.forename: Regan B
authors.initials: RB
authors.lastname: Stuart-Killion
authors.forename: Brian M
authors.initials: BM
authors.lastname: Daniel
authors.forename: Laura B
authors.initials: LB
authors.lastname: Presnell
authors.forename: Hanjing
authors.initials: H
authors.lastname: Zhuo
authors.forename: Michael A
authors.initials: MA
authors.lastname: Matthay
authors.forename: Kathleen D
authors.initials: KD
authors.lastname: Liu
mesh_terms: D006348:Cardiac Surgical Procedures / Q000009:adverse effects; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006330:Heart Defects, Congenital / Q000601:surgery*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007902:Length of Stay; D008297:Male; D016017:Odds Ratio; D011182:Postoperative Care; D011237:Predictive Value of Tests; D012372:ROC Curve; D012044:Regression Analysis; D012121:Respiration, Artificial; D012126:Respiratory Dead Space / Q000502:physiology*