title: The influence of positive end-expiratory pressure on stroke volume variation in patients undergoing cardiac surgery: an observational study.
abstract: OBJECTIVE
  Measurements of stroke volume variation for volume management in mechanically ventilated patients are influenced by various factors, such as tidal volume, respiratory rate, and chest/lung compliance. However, research regarding the effect of positive end-expiratory pressure on stroke volume variation is limited.
  
  
  METHODS
  Patients were divided into responder and nonresponder groups according to the prediction of fluid response by the passive leg raising test and hemodynamic parameters, including stroke volume variation, measured in all patients at the following ventilator settings: (1) conventional ventilation (C), tidal volume 10 mL · kg(-1) with positive end-expiratory pressure settings of 0 (C0), 5 (C5), and 10 cmH2O (C10) and (2) lung protective ventilation (P), tidal volume 6 mL · kg(-1) with positive end-expiratory pressure settings of 0 (P0), 5 (P5), and 10 cmH2O (P10).
  
  
  RESULTS
  Regardless of ventilator setting, stroke volume variation in the responder group had an increasing trend as increased positive end-expiratory pressure level and was significantly higher than in the nonresponder group at each positive end-expiratory pressure level. The area under the curve was (1) 0.899 at C0, 0.942 at C5, and 0.985 at C10; and (2) 0.901 at P0, 0.932 at P5, and 0.947 at P10. Optimal threshold values given by receiver operating characteristic curve analysis were (1) 13.5%, 13.5%, and 14.5%; and (2) 13.5%, 13.5%, and 14.5%, respectively.
  
  
  CONCLUSIONS
  The threshold value of stroke volume variation in predicting fluid responsiveness may change when positive end-expiratory pressure 10 cmH2O is applied. This must be considered when stroke volume variation is used to detect the fluid responsiveness to prevent volume overload in this mechanical ventilation setting.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Korea; Institute of Biomedical Science and Technology, Konkuk University School of Medicine, Seoul, Korea.
authors.forename: Woon-Seok
authors.initials: WS
authors.lastname: Kang
authors.affiliation: Department of Anesthesiology and Pain Medicine, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Korea; Institute of Biomedical Science and Technology, Konkuk University School of Medicine, Seoul, Korea. Electronic address: yshkim75@daum.net.
authors.forename: Seong-Hyop
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Anesthesiology and Pain Medicine, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Korea.
authors.forename: Sung Yun
authors.initials: SY
authors.lastname: Kim
authors.affiliation: Department of Anesthesiology and Pain Medicine, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Korea.
authors.forename: Chung-Sik
authors.initials: CS
authors.lastname: Oh
authors.affiliation: Institute of Biomedical Science and Technology, Konkuk University School of Medicine, Seoul, Korea; Department of Thoracic and Cardiovascular Surgery, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Korea.
authors.forename: Song-Am
authors.initials: SA
authors.lastname: Lee
authors.affiliation: Institute of Biomedical Science and Technology, Konkuk University School of Medicine, Seoul, Korea; Department of Thoracic and Cardiovascular Surgery, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Korea.
authors.forename: Jun-Seok
authors.initials: JS
authors.lastname: Kim
mesh_terms: D000328:Adult; D001022:Aortic Valve Insufficiency / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D001024:Aortic Valve Stenosis / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D019540:Area Under Curve; D006348:Cardiac Surgical Procedures / Q000009:adverse effects; D005260:Female; D005440:Fluid Therapy; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods*; D011175:Positive-Pressure Respiration / Q000009:adverse effects; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D013318:Stroke Volume; D013997:Time Factors; D016896:Treatment Outcome