2006 OPEN FORUM Abstracts
THE IMPORTANCE of Ideal body weight for tidal volume calculation
Anthony J. Asciutto RRT, David L. Michaels RRT,
Michael A. Gentile RRT FAARC, John D. Davies RRT FAARC, Neil R. MacIntyre MD FAARC.
Duke University Medical Center, Durham, NC.
Background: Studies
involving both human and laboratory subjects have shown that the selection of
incorrect delivered tidal volumes (Vt) can cause ventilator induced lung injury
(VILI). The ARDSnet study1 showed that the
group of patients receiving Vt of 6 ml/kg
ideal body weight (IBW) was associated with a lower mortality compared with the group receiving Vt of 12 ml/kg IBW. The purpose
of this study was to compare IBW to actual body weight (ABW) and estimate the gap in Vt based on the difference of
IBW and ABW.
Methods: We retrospectively examined a sample of ventilated patients and calculated the
value of delivered tidal volume over IBW during conventional
mechanical ventilation. Data (Vt, IBW, ABW) were gathered on all ventilated patients in adult
intensive care units over a single 12 hours shift.
Results: In
37 ventilated patients, the value of delivered tidal volume over IBW ranged from 4.9 ml/Kg to 10.5 ml/Kg. The
disparity of ABW and IBW (ABW-IBW) ranged from -7 Kg to +119 Kg (p < 0.05). If tidal volume of 6 ml/Kg was applied, the
estimated gap of tidal volume resulting from the difference of IBW and ABW
would maximally reach 714 ml.
Conclusion: The difference between IBW and ABW is significant. The use of IBW instead of ABW for the basis
of Vt calculation resulted in lower Vt in our
institution and may help reduce the incidence of VILI.
1. Ventilation with Lower Tidal Volumes as
Compared with Traditional Tidal Volumes for Acute Lung Injury and the Acute
Respiratory Distress Syndrome. The Acute Respiratory Distress Syndrome Network , N Engl J Med. 2000;342:1301-1308.