Comparison of Usual and Alternative Methods to Measure Height in Mechanically Ventilated Patients: Potential Impact on Protective Ventilation

Bojmehrani, Azadeh; Bergeron-Duchesne, Maude; Bouchard, Carmelle; Simard, Serge; Bouchard, Pierre-Alexandre; Vanderschuren, Abel; L’Her, Erwan; Lellouche, François

doi:10.4187/respcare.02732

Cited by 20 publications

(29 citation statements)

References 47 publications

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“…This is similar to the results of Bojmehrani et al 5 (visual height ϭ 169.6 cm, tape measure height ϭ 169.4 cm, ulnar-based height ϭ167.2 cm). Their study concluded that in com- parison with the reference method, estimating the height visually and using the tape measure (potential sources of our EHR data) were less accurate than ulnar-based measurements.…”

Section: Discussionsupporting

confidence: 81%

“…However, visual estimates and even bedside tape measurements of height in ventilated patients may be inaccurate. 5 A possible alternative source of data is the height predicted by ulnar length. 6 The purposes of this study were (1) to evaluate the difference between patient height of unknown origin charted in the EHR and height based on ulnar length and (2) to determine the effect of the height difference in setting lung-protective V T during mechanical ventilation.…”

Section: Introductionmentioning

confidence: 99%

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Accuracy of the Electronic Health Record: Patient Height

2015

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BACKGROUND: Protective lung ventilation requires calculating predicted body weight (BW) from height. Thus, inaccuracy of height data in the electronic health record (EHR) is a risk factor for ventilator-induced lung injury. Charted height data often have uncertain accuracy. Study purposes were (1) to evaluate the difference between patient height charted in the EHR and predicted height (PH) from ulnar length and (2) to determine how the height data source affects predicted BW and the resulting values for protective tidal volume (V T ). METHODS: Subject height data from the EHR were collected from several ICUs. Simultaneous ulnar data were collected by measuring ulnar length (cm): male PH (cm) ‫؍‬ 79.2 ؎ 3.60 ؋ ulnar length; female PH ‫؍‬ 95.6 ؎ 2.77 ؋ ulnar length. For each subject, BW (kg) was calculated from height charted in EHR and from predicted height: male BW ‫؍‬ 50 ؎ 0.91 ؋ (height ؊ 152.4); female BW ‫؍‬ 45.5 ؎ 0.91 ؋ (height ؊ 152.4). Then V T was calculated as 8 mL/kg BW. Bland-Altman analysis of height and V T differences (charted ؊ predicted) determined the limits of agreement. RESULTS: For white males (n ‫؍‬ 27) the mean (SD) height from EHR was 177 (7.5); predicted height was 178 (6.9). The limits of agreement for height in males were ؊18.5 and 17.8 cm. The limits of agreement for females were ؊23.1 and 21.3 cm. The limits of agreement for V T in males were ؊1.8 and 1.8 mL/kg. The limits of agreement for V T in females were ؊3.0 and 2.9 mL/kg. CONCLUSIONS: For overall populations, mean height calculated from values charted in the EHR is similar to that estimated from ulnar length. However, for individuals, differences in height between the 2 sources can be large, leading to large differences in predicted BW and resultant V T set in terms of mL/kg.

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Section: Discussionsupporting

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Accuracy of the Electronic Health Record: Patient Height

2015

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“…Subsequent observational trials have demonstrated that height is often overestimated to the detriment of some patients, especially in the case of short and obese females. [5][6][7] The low frequency of heelto-crown height measurements in patients with ARDS is probably due to multiple factors, including time, perceived inaccuracy of height measurements in a critically ill supine patient, and a lack of appreciation that accurate height measurements can alter mortality.The study by Jurecki et al 8 explores the complexity of setting low V T for the purpose of lung-protective ventilation; the variation in estimated set V T depends on height estimates which may vary considerably depending on the source used to estimate height. The authors found that, for the study population, the mean height obtained from the electronic health record is similar to the mean predicted height calculated from ulnar length.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Low Tidal Volume Ventilation: Trust but Verify

Ghamloush

Garpestad

2015

Respir Care

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Despite affecting an estimated 4 -7% of patients in the ICU and having a high mortality rate, there are currently a limited number of therapeutic options to treat patients with ARDS. 1,2 ARMA, the landmark ARDSnet trial in 2000, established the concept of lungprotective ventilation, where subjects with ARDS receiving mechanical ventilation were randomly assigned to a set tidal volume (V T ) of either 6 or 12 mL/kg predicted body weight, calculated from measured height. 3 This trial demonstrated a significant reduction in mortality in the low V T arm. As a consequence, it provided strong evidence for abandoning the conventional wisdom of setting ventilation to normalize pH and P CO 2 in favor of the emerging view that protective low V T ventilation and permissive hypercapnia could avoid pulmonary mechanical stress and ventilator-induced lung injury (VILI). Although not explicitly stated in the original publication, the ARMA trial used heelto-crown height measured in supine subjects. 4 Although clinical practice has shifted toward targeting lower V T levels estimated from height, height measurements have not been standardized; in the real world, height is often obtained from patients or family members, or visually estimated by staff. Subsequent observational trials have demonstrated that height is often overestimated to the detriment of some patients, especially in the case of short and obese females. [5][6][7] The low frequency of heelto-crown height measurements in patients with ARDS is probably due to multiple factors, including time, perceived inaccuracy of height measurements in a critically ill supine patient, and a lack of appreciation that accurate height measurements can alter mortality.The study by Jurecki et al 8 explores the complexity of setting low V T for the purpose of lung-protective ventilation; the variation in estimated set V T depends on height estimates which may vary considerably depending on the source used to estimate height. The authors found that, for the study population, the mean height obtained from the electronic health record is similar to the mean predicted height calculated from ulnar length. However, for individuals, differences in height between the 2 sources can be large, leading to large differences in predicted body weight and resultant V T set in mL/kg. The authors did not obtain the accepted standard heel-to-crown height measurements SEE THE ORIGINAL STUDY ON PAGE 1715 that were obtained in ARMA; hence, a purist would argue that, in the absence of such measurements, it would be pure speculation which of the height estimations one should follow in setting V T . However, the results are still of interest because they show a real difference between the 2 methods of estimating set V T , with clear consequences for individual subjects. For example, a visual scan of the BlandAltman plots demonstrates that at least 6 of 27 males (22%) and at least 6 of 24 females (25%) had differences between charted and predicted average V T /predicted body weight Ͼ1 mL/kg when the authors ass...

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“…The article by Dr Bojmehrani and colleagues published in the present issue of RESPIRATORY CARE perfectly fits this context. 5 They studied the potential impact of differently measured heights on protective ventilation by comparing usual (estimation or tape measurement while patient is supine) and alternative (based on lower leg and forearm dimensions) measuring methods. Height measured in the upright position served as the accepted standard.…”

mentioning

confidence: 99%