title: Effect of cardiopulmonary bypass and aortic clamping on functional residual capacity and ventilation distribution in children.
abstract: OBJECTIVE
  To characterize factors that contribute to lung function impairment after cardiopulmonary bypass, we assessed functional residual capacity and ventilation homogeneity during the perioperative period in children with congenital heart disease who are to undergo surgical repair.
  
  
  METHODS
  Functional residual capacity and lung clearance index were measured by using a sulfur hexafluoride washout technique in 24 children (aged 0-10 years). Measurements of functional residual capacity and ventilation distribution were performed after induction of anesthesia, at different stages of the surgical procedure, and up to 90 minutes after skin closure. Anesthesia was standardized, and ventilator settings, including the fraction of inspired oxygen, were kept constant throughout the study period.
  
  
  RESULTS
  Sternotomy and retractor insertion led to a significant increase in functional residual capacity (mean [SD], 24% [14%]), followed by a similar percentage decrease in the resting volume after a significant reduction in pulmonary blood flow during cardiopulmonary bypass with aortic clamping. Although reestablishing pulmonary blood flow increased functional residual capacity (10% [6%]), chest closure led to a decrease in functional residual capacity of 36% (14%) that only slightly improved during the first 90 minutes after surgical intervention. Changes in lung clearance index were affected conversely compared with changes in functional residual capacity at all assessment times.
  
  
  CONCLUSIONS
  These results confirmed that chest wall condition and pulmonary circulation affect lung volumes and ventilation homogeneity. Although opening of the chest wall improved alveolar recruitment and ventilation homogeneity, blood flow appeared essential for alveolar stability, presumably by exerting a tethering force caused by the filled capillaries on the alveolar walls and therefore contributing to an increase in resting lung volume.
authors.affiliation: Pediatric Anesthesia Unit, Geneva Children's Hospital, Geneva, Switzerland. britta.reglivonungern@hcuge.ch
authors.forename: Britta S
authors.initials: BS
authors.lastname: von Ungern-Sternberg
authors.forename: Ferenc
authors.initials: F
authors.lastname: Petak
authors.forename: Sonja
authors.initials: S
authors.lastname: Saudan
authors.forename: Michel
authors.initials: M
authors.lastname: Pellegrini
authors.forename: Thomas O
authors.initials: TO
authors.lastname: Erb
authors.forename: Walid
authors.initials: W
authors.lastname: Habre
mesh_terms: D001011:Aorta / Q000601:surgery; D002315:Cardiopulmonary Bypass / Q000009:adverse effects*; D002648:Child; D002675:Child, Preschool; D003250:Constriction; D005260:Female; D005652:Functional Residual Capacity; D006330:Heart Defects, Congenital / Q000601:surgery*; D006801:Humans; D007223:Infant; D008171:Lung Diseases / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D012123:Pulmonary Ventilation; D014656:Vascular Surgical Procedures / Q000009:adverse effects*