The Science Journal of the American Association for Respiratory Care

2009 OPEN FORUM Abstracts

A PRELIMINARY COMPARISON OF DELIVERED TIDAL VOLUME AND ARDSNET RECOMMENDED TIDAL VOLUME AS DETERMINED BY IDEAL BODY WEIGHT IN MECHANICALLY VENTILATED PATIENTS

Susan R. Whiddon, Randall Baker, Christen Adcock, Amanda Hadden, Robin Smith; Respiratory Therapy, Medical College of Georgia, Augusta, GA

Background: The first ARDSnet randomized controlled trial, demonstrated that patients receiving tidal volumes (Vt) of 6ml/kg experienced lower mortality compared to the group receiving tidal volumes of 12ml/kg. The tidal volumes delivered were based upon a calculation of ideal body weight (IBW) based on height. However, frequently there are no policies in place for using a tidal volume based upon a determination of ideal body weight. Therefore, many facilities do not have a specific protocol for determining a patient’s ideal body weight, and ultimately, have no set method to determine an appropriate tidal volume. This study used a simple forearm measurement to estimate height in order to calculate each subject’s IBW. Actual delivered volumes (ml/kg IBW) were compared with tidal volumes calculated to match the ARDSnet recommendation of 6 ml/kg IBW. Methods: After receiving IRB approval, a convenience sample of subjects was chosen from existing mechanically ventilated patients in the ICU at a community hospital in March, 2009. Subjects in the study included 20 adult ICU patients both male(n=15) and female(n=5), over 18 years of age receiving mechanical ventilation. Information collected included demographics data, delivered Vt, and mode of ventilation. Height was estimated using forearm length based upon a co-study that assessed height in recumbent adults. Ideal Body Weight was calculated using the Predicted Body Weight equation. Recommended Vt was based on IBW using ARDSnet recommendations of 6 mL/kg. Results: By comparing the recommended Vt based on the IBW measurement and the actual delivered Vt, we found that 40% of the patients were ventilated at tidal volumes of > 6ml/kg IBW, and 10% of the patients were being ventilated at tidal volumes of <6ml/kg. Conclusion: Forearm length is easily measured and can be integrated into the initial patient assessment. This study showed that 40% of patients are ventilated at higher volumes based on ARDSnet recommendations. The forearm measurement should be incorporated in the patient assessment to predict height in order to determine IBW, and therefore, deliver an appropriate Vt. Sponsored Research - None

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