ADULT TIDAL VOLUME CHART TV

First, we determined the proportion of the cohort for which each method could be used to successfully calculate the IBW second, we compared the level of agreement between each possible combination of 2 out of the 4 IBW methods by Bland Altman analysis( 11, 12) finally, we evaluated the differences in tidal volume prescribed by each method. We compared these 4 methods to determine whether one method may be better suited to prescribe tidal volume and provide lung protective ventilation strategies than the others. However, there is no gold standard method to determine IBW in children.įour IBW methods are commonly used in pediatrics: ( 1) National Center for Health Statistics data tables( 7), ( 2) the McLaren method( 8), ( 3) the Moore method( 9), and ( 4) the body mass index (BMI) method( 10). It makes sense, then, that IBW be used for the prescription of tidal volumes in pediatric ARDS( 4– 6). Height, and therefore IBW, are excellent predictors of lung volume, which increases as the size of the thoracic cavity increases. Ideal body weight (IBW), also referred to as predicted body weight, is a calculated weight determined for a specific age or height that is deemed optimal for nutritional status( 3). Recently, the Pediatric Acute Lung Injury Consensus Conference recommended a similar strategy, stating “tidal volumes should be 3–6 mL/kg predicted body weight for patients with poor respiratory system compliance and closer to the physiologic range (5–8 mL/kg ideal body weight) for patients with better preserved respiratory system compliance”( 2). This is based on the assumption that volutrauma might be minimized by delivering a volume appropriate to the patient’s lung capacity( 1). A key element of a lung protective strategy is the application of a minimal tidal volume scaled to a predicted rather than actual body weight. Lung protective ventilation strategy has become the standard of care in adults with acute respiratory distress syndrome (ARDS)( 1).

ADULT TIDAL VOLUME CHART TV

The McLaren method had the best agreement with all other methods, and yielded similar prescribed TV in 2–10 year olds and lower TV in ≥10 years old. This variance was greatest between Moore and BMI methods with ≥10Kg difference in IBW in some subjects. In comparing each method to the others, there was great variance, particularly in ≥10 year olds. NCHS, McLaren and Moore methods could calculate IBW in ≥90%, while BMI method was successful in only 61% due to no BMI validation in <2 year olds. Only 55% could have IBW measured by all four methods. We a priori defined the better method to be one that could calculate IBW in most subjects, had good agreement with other methods, and led to a lower TV. All rights reserved.IBW was calculated by 4 common methods: National Center for Health Statistics (NCHS), McLaren, Moore, and BMI, and compared in 3 ways: ( 1) determine the proportion of the cohort for which each method could successfully calculate IBW, ( 2) compare the level of agreement between the IBW methods by Bland-Altman analysis, ( 3) evaluate the difference in TV when 6mL/Kg IBW was prescribed. These findings suggest that targeting tidal volume by using the lower of measured and predicted body weights would be the most lung-protective strategy.ĪRDS BMI children pulmonary function test.Ĭopyright © 2018 American College of Chest Physicians. Children with low or normal BMI have lung volumes reflecting measured body weight. Obese children have lung volumes reflecting their predicted body weight from height. A decline in median FVC from measured weight (from 69.4 to 37.6 mL/kg) as BMI z score group increased was also seen.įVC differs significantly when standardizing to measured weight vs predicted weight. Dataset two included 8,472 patient PFTs from clinical measurement. FVC from predicted weight increased slightly with increasing BMI z score group. The median FVC from measured weight was 81.4 mL/kg in the lowest BMI z score group and 51.7 mL/kg in the highest BMI z score group. FVC from measured weight decreased as the BMI z score group increased. FVC mL/kg values were analyzed against BMI z scores to show changes in FVC vs BMI between measured and predicted weight.ĭataset one included 5,394 PFTs from the Canadian survey.

Dataset two included 6- to 20-year-old patients undergoing PFTs at a freestanding children's hospital. Dataset one included 6- to 19-year-old patients undergoing PFTs from the nationally representative Canadian Health Measures Survey.

This retrospective analysis included outpatient pulmonary function tests (PFTs) from two datasets. The goal of this study was to examine the difference in FVC (in milliliters per kilogram ) by using measured body weight compared with predicted body weight in children. Tidal volumes standardized to predicted body weight are recommended for adult mechanical ventilation, but children are frequently ventilated by using measured body weight.

Adult tidal volume chart