title: Manual hyperinflation partly prevents reductions of functional residual capacity in cardiac surgical patients--a randomized controlled trial.
abstract: BACKGROUND
  Cardiac surgery is associated with post-operative reductions of functional residual capacity (FRC). Manual hyperinflation (MH) aims to prevent airway plugging, and as such could prevent the reduction of FRC after surgery. The main purpose of this study was to determine the effect of MH on post-operative FRC of cardiac surgical patients.
  
  
  METHODS
  This was a randomized controlled trial of patients after elective coronary artery bypass graft and/or valve surgery admitted to the intensive care unit (ICU) of a university hospital. Patients were randomly assigned to a "routine MH group" (MH was performed within 30 minutes after admission to the ICU and every 6 hours thereafter, and before tracheal extubation), or a "control group" (MH was performed only if perceptible (audible) sputum was present in the larger airways causing problems with mechanical ventilation, or if oxygen saturation (SpO2) dropped below 92%). The primary endpoint was the reduction of FRC from the day before cardiac surgery to one, three, and five days after tracheal extubation. Secondary endpoints were SpO2 (at similar time points) and chest radiograph abnormalities, including atelectasis (at three days after tracheal extubation).
  
  
  RESULTS
  A total of 100 patients were enrolled. Patients in the routine MH group showed a decrease of FRC on the first post-operative day to 71% of the pre-operative value, versus 57% in the control group (P = 0.002). Differences in FRC became less prominent over time; differences between the two study groups were no longer statistically significant at Day 5. There were no differences in SpO2 between the study groups. Chest radiographs showed more abnormalities (merely atelectasis) in the control group compared to patients in the routine MH group (P = 0.002).
  
  
  CONCLUSIONS
  MH partly prevents the reduction of FRC in the first post-operative days after cardiac surgery.
  
  
  BACKGROUND
  Netherlands Trial Register (NTR): NTR1384. http://www.trialregister.nl.
authors.affiliation: Department of Intensive Care Medicine, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. f.paulus@amc.uva.nl.
authors.forename: Frederique
authors.initials: F
authors.lastname: Paulus
authors.forename: Denise P
authors.initials: DP
authors.lastname: Veelo
authors.forename: Selma B
authors.initials: SB
authors.lastname: de Nijs
authors.forename: Ludo F M
authors.initials: LF
authors.lastname: Beenen
authors.forename: Paul
authors.initials: P
authors.lastname: Bresser
authors.forename: Bas A J M
authors.initials: BA
authors.lastname: de Mol
authors.forename: Jan M
authors.initials: JM
authors.lastname: Binnekade
authors.forename: Marcus J
authors.initials: MJ
authors.lastname: Schultz
mesh_terms: D000368:Aged; D001026:Coronary Artery Bypass; D003422:Critical Care / Q000379:methods; D005260:Female; D005652:Functional Residual Capacity / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D011175:Positive-Pressure Respiration / Q000379:methods*; D011184:Postoperative Period; D013990:Tidal Volume / Q000502:physiology