title: Comparative evaluation of hemodynamic and respiratory parameters during mechanical ventilation with two tidal volumes calculated by demi-span based height and measured height in normal lungs.
abstract: BACKGROUND
  Appropriate determination of tidal volume (VT) is important for preventing ventilation induced lung injury. We compared hemodynamic and respiratory parameters in two conditions of receiving VTs calculated by using body weight (BW), which was estimated by measured height (HBW) or demi-span based body weight (DBW).
  
  
  METHODS
  This controlled-trial was conducted in St. Alzahra Hospital in 2009 on American Society of Anesthesiologists (ASA) I and II, 18-65-years-old patients. Standing height and weight were measured and then height was calculated using demi-span method. BW and VT were calculated with acute respiratory distress syndrome-net formula. Patients were randomized and then crossed to receive ventilation with both calculated VTs for 20 min. Hemodynamic and respiratory parameters were analyzed with SPSS version 20.0 using univariate and multivariate analyses.
  
  
  RESULTS
  Forty nine patients were studied. Demi-span based body weight and thus VT (DTV) were lower than Height based body weight and VT (HTV) (P = 0.028), in male patients (P = 0.005). Difference was observed in peak airway pressure (PAP) and airway resistance (AR) changes with higher PAP and AR at 20 min after receiving HTV compared with DTV.
  
  
  CONCLUSIONS
  Estimated VT based on measured height is higher than that based on demi-span and this difference exists only in females, and this higher VT results higher airway pressures during mechanical ventilation.
authors.affiliation: Department of Obstetrics and Gynecology, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: L Mousavi
authors.initials: LM
authors.lastname: Seresht
authors.affiliation: Department of Anesthesia and Intensive Care, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Golparvar
authors.affiliation: Department of Anesthesia and Intensive Care, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Yaraghi
keywords: Critical care; demi-span; tidal volume; ventilation