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


1 Department of Obstetrics and Gynecology, Isfahan University of Medical Sciences, Isfahan, Iran

2 Department of Anesthesia and Intensive Care, Isfahan University of Medical Sciences, Isfahan, Iran


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).
Materials and 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.


1. Grasso S, Mascia L, Ranieri VM. Respiratory care. In: Miller RD, editor. Miller's Anesthesia. 7 th ed. Philadelphia: Churchill Livingstone; 2010. p. 2880.  Back to cited text no. 1
2. Cortés I, Peñuelas O, Esteban A. Acute respiratory distress syndrome: Evaluation and management. Minerva Anestesiol 2012;78:343-57.  Back to cited text no. 2
3. Tunnicliffe B. Mechanical ventilation. In: Smith FG, editor. Core Topics in Critical Care Medicine. 1 th ed. New York: Cambridge University Press; 2010. p. 215.  Back to cited text no. 3
4. Lipes J, Bojmehrani A, Lellouche F. Low Tidal Volume Ventilation in Patients without Acute Respiratory Distress Syndrome: A Paradigm Shift in Mechanical Ventilation. Crit Care Res Pract 2012;2012:416862.  Back to cited text no. 4
5. Thille AW, Rodriguez P, Cabello B, Lellouche F, Brochard L. Patient-ventilator asynchrony during assisted mechanical ventilation. Intensive Care Med 2006;32:1515-22.  Back to cited text no. 5
6. Haas CF, Bauser KA. Advanced ventilator modes and techniques. Crit Care Nurs Q 2012;35:27-38.  Back to cited text no. 6
7. Hickson M, Frost G. A comparison of three methods for estimating height in the acutely ill elderly population. J Hum Nutr Diet 2003;16:13-20.  Back to cited text no. 7
8. Deane AM, Reid DA, Tobin AE. Predicted body weight during mechanical ventilation: Using arm demispan to aid clinical assessment. Crit Care Resusc 2008;10:14.  Back to cited text no. 8
9. Hirani V, Mindell J. A comparison of measured height and demi-span equivalent height in the assessment of body mass index among people aged 65 years and over in England. Age Ageing 2008;37:311-7.  Back to cited text no. 9
10. Goulenok C, Monchi M, Chiche JD, Mira JP, Dhainaut JF, Cariou A. Influence of overweight on ICU mortality: A prospective study. Chest 2004;125:1441-5.  Back to cited text no. 10
11. Bercault N, Boulain T, Kuteifan K, Wolf M, Runge I, Fleury JC. Obesity-related excess mortality rate in an adult intensive care unit: A risk-adjusted matched cohort study. Crit Care Med 2004;32:998-1003.  Back to cited text no. 11
12. O'Brien JM Jr, Welsh CH, Fish RH, Ancukiewicz M, Kramer AM. National Heart, Lung, and Blood Institute Acute Respiratory Distress Syndrome Network. Excess body weight is not independently associated with outcome in mechanically ventilated patients with acute lung injury. Ann Intern Med 2004;140:338-45.  Back to cited text no. 12