title: The impact of sedation on pulse pressure variation.
abstract: OBJECTIVE
  Pulse pressure variations (PPV) are mainly influenced by ventilation. The impact of sedation on PPV is not known. The aim of the study was to test the influence of sedation on pulse pressure variation in mechanically ventilated critically ill patients and to compare PPV in critically ill and brain dead patients. Beside the absolute value of PPV, the adjusted values of pulse pressure were used to eliminate influence of ventilation.
  
  
  METHODS
  Mechanically ventilated patients received four different breath frequencies. At each frequency airway pressure was adjusted to keep the end-tidal CO2 stable. In critically ill patients the frequencies were applied at basal (bispectral index - BIS median 38) and deeper sedation (BIS 29).
  
  
  METHODS
  Simultaneous haemodynamic and respiratory data including oesophageal pressure were recorded, adjusted PPV were calculated as PPV/VT, PPV/dPair, PPV/dPes where VT is tidal volume, dPair and dPes are airway and oesophageal driving pressures.
  
  
  METHODS
  University Hospital, ICU.
  
  
  METHODS
  30 critically ill and 23 patients with a diagnosis of brain death.
  
  
  RESULTS
  The pulse pressure variation did not change significantly during deep sedation compared to basal sedation (median 10.3 vs 10.9%) whereas PPV/dPair increased from 0.7 to 0.8%/cmH2O and PPV/dPes from 1.9%/cmH2O to 2.4%/cmH2O (p=0.04). Patients with a diagnosis of brain death had higher PPV and adjusted PPV than critically ill patients.
  
  
  CONCLUSIONS
  Deeper sedation increases values of adjusted pulse pressure variation.
authors.affiliation: Department of Anaesthesiology and Intensive Care, St. Anne's University Hospital and Masaryk University, Brno, Czech Republic.
authors.forename: Vaclav
authors.initials: V
authors.lastname: Zvonicek
authors.affiliation: Institute of Scientific Instruments, Academy of Sciences, Brno, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Jurak
authors.affiliation: Institute of Scientific Instruments, Academy of Sciences, Brno, Czech Republic.
authors.forename: Josef
authors.initials: J
authors.lastname: Halamek
authors.affiliation: Department of Cardiovascular Diseases, International Clinical Research Center, St. Anne's University Hospital and Masaryk University, Brno, Czech Republic. Electronic address: peter.kruzliak@savba.sk.
authors.forename: Peter
authors.initials: P
authors.lastname: Kruzliak
authors.affiliation: Institute of Scientific Instruments, Academy of Sciences, Brno, Czech Republic.
authors.forename: Vlastimil
authors.initials: V
authors.lastname: Vondra
authors.affiliation: Department of Cardiovascular Diseases, International Clinical Research Center, St. Anne's University Hospital and Masaryk University, Brno, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Leinveber
authors.affiliation: Department of Anaesthesiology and Intensive Care, St. Anne's University Hospital and Masaryk University, Brno, Czech Republic.
authors.forename: Ivan
authors.initials: I
authors.lastname: Cundrle
authors.affiliation: Department of Anaesthesiology and Intensive Care, St. Anne's University Hospital and Masaryk University, Brno, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Pavlík
authors.affiliation: Department of Anaesthesiology and Intensive Care, St. Anne's University Hospital and Masaryk University, Brno, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Suk
authors.affiliation: Department of Anaesthesiology and Intensive Care, St. Anne's University Hospital and Masaryk University, Brno, Czech Republic.
authors.forename: Vladimír
authors.initials: V
authors.lastname: Sramek
mesh_terms: D000368:Aged; D001794:Blood Pressure / Q000502:physiology*; D001926:Brain Death; D016638:Critical Illness; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration; D012121:Respiration, Artificial
keywords: Brain death; Heart lung interactions; Mechanical ventilation; Oesophageal pressure; Pulse pressure variation; Sedation