Objectives

No gold standard for ideal body weight determination in children exists. We aimed to compare four methods of ideal body weight calculation and determine level of agreement between methods and impact of measurement variance on tidal volumes prescribed in mechanically ventilated pediatric acute respiratory distress syndrome.

Design

Post hoc analysis of four multicenter pediatric acute respiratory distress syndrome studies.

Setting

Twenty-six academic PICUs.

Patients

Five hundred eighty-nine patients.

Interventions

None.

Measurements and main results

Ideal body weight was calculated by four common methods: National Center for Health Statistics, McLaren, Moore, and body mass index, and compared in three ways: 1) determine the proportion of the cohort for which each method could successfully calculate ideal body weight; 2) compare the level of agreement between the ideal body weight methods by Bland-Altman analysis; and 3) evaluate the difference in tidal volume when 6 mL/kg ideal body weight was prescribed. We a priori defined the better method to be one that could calculate ideal body weight in most subjects, had good agreement with other methods, and led to a lower tidal volume. Only 55% could have ideal body weight measured by all four methods. National Center for Health Statistics, McLaren, and Moore methods could calculate ideal body weight in greater than or equal to 90%, whereas body mass index method was successful in only 61% because of no body mass index validation in less than 2-year-olds. In comparing each method to the others, there was great variance, particularly in greater than or equal to 10-year-olds. This variance was greatest between Moore and body mass index methods with greater than or equal to 10 kg difference in ideal body weight in some subjects. The McLaren method had the best agreement with all other methods, and yielded similar prescribed tidal volume in 2- to 10-year-olds and lower tidal volume in greater than or equal to 10 years old.

Conclusions

There is substantial variation in calculated ideal body weight among four commonly used methods, particularly in adolescents. Since varying ideal body weight may lead to discrepancies in pediatric acute respiratory distress syndrome care, a standard approach to ideal body weight measurement is needed. We recommend the McLaren method to calculate ideal body weight in children with pediatric acute respiratory distress syndrome until a gold standard method is validated.

Many caregivers of patients with neurodegenerative disease experience physical and psychological strain, which is associated with negative health outcomes. Caregiver strain may be partly attributable to negative emotional responses (e.g.of resentment) to the behavioral, cognitive, and physical changes associated with patients' disease. The philosopher Peter Strawson observed that in dealing with people who have neurological impairments, we often choose to suspend such emotional responses, adopting what he labeled the "objective attitude," though this may come at the expense of our relationships with them. In this study, we assessed the mediating effect of caregivers' adoption of the objective attitude on caregiver strain and relationship closeness in the setting of disease progression. Caregivers of patients with neurodegenerative disorders (n = 215) completed the Clinical Dementia Rating, Relationship-Closeness scale, Caregiver Strain Index, and a novel questionnaire assessing the adoption of the objective attitude. A structural equation model assessing associations among these variables demonstrated good fit (χ² (88)=164.621, p < 0.001; CFI = 0.929, RMSEA = 0.064.) and showed that adoption of the objective attitude mediated the association between disease progression and relationship closeness (total β= -0.233, 95% CI: -0.351, -0.113; indirect β= -0.483, 95% CI: -0.602, -0.364; direct β = 0.250, 95% CI: 0.117, 0.384), but did not mediate the association between disease progression and caregiver strain (total β = 0.323, 95% CI: 0.234, 0.412; indirect β = 0.089, 95% CI: -0.027, 0.206; direct β = 0.153, 95% CI: -0.043, 0.349). For future work, we propose longitudinal measurements of these constructs to test the directionality of associations and consideration of how models for caregiver support can draw upon interdisciplinary insights.

Circuit mapping requires knowledge of both structural and functional connectivity between cells. Although optical tools have been made to assess either the morphology and projections of neurons or their activity and functional connections, few probes integrate this information. We have generated a family of photoactivatable genetically encoded Ca(2+) indicators that combines attributes of high-contrast photolabeling with high-sensitivity Ca(2+) detection in a single-color protein sensor. We demonstrated in cultured neurons and in fruit fly and zebrafish larvae how single cells could be selected out of dense populations for visualization of morphology and high signal-to-noise measurements of activity, synaptic transmission and connectivity. Our design strategy is transferrable to other sensors based on circularly permutated GFP (cpGFP).

Objectives

To determine the frequency of low-tidal volume ventilation in pediatric acute respiratory distress syndrome and assess if any demographic or clinical factors improve low-tidal volume ventilation adherence.

Design

Descriptive post hoc analysis of four multicenter pediatric acute respiratory distress syndrome studies.

Setting

Twenty-six academic PICU.

Patients

Three hundred fifteen pediatric acute respiratory distress syndrome patients.

Measurements and main results

All patients who received conventional mechanical ventilation at hours 0 and 24 of pediatric acute respiratory distress syndrome who had data to calculate ideal body weight were included. Two cutoff points for low-tidal volume ventilation were assessed: less than or equal to 6.5 mL/kg of ideal body weight and less than or equal to 8 mL/kg of ideal body weight. Of 555 patients, we excluded 240 for other respiratory support modes or missing data. The remaining 315 patients had a median PaO2-to-FIO2 ratio of 140 (interquartile range, 90-201), and there were no differences in demographics between those who did and did not receive low-tidal volume ventilation. With tidal volume cutoff of less than or equal to 6.5 mL/kg of ideal body weight, the adherence rate was 32% at hour 0 and 33% at hour 24. A low-tidal volume ventilation cutoff of tidal volume less than or equal to 8 mL/kg of ideal body weight resulted in an adherence rate of 58% at hour 0 and 60% at hour 24. Low-tidal volume ventilation use was no different by severity of pediatric acute respiratory distress syndrome nor did adherence improve over time. At hour 0, overweight children were less likely to receive low-tidal volume ventilation less than or equal to 6.5 mL/kg ideal body weight (11% overweight vs 38% nonoverweight; p = 0.02); no difference was noted by hour 24. Furthermore, in the overweight group, using admission weight instead of ideal body weight resulted in misclassification of up to 14% of patients as receiving low-tidal volume ventilation when they actually were not.

Conclusions

Low-tidal volume ventilation is underused in the first 24 hours of pediatric acute respiratory distress syndrome. Age, Pediatric Risk of Mortality-III, and pediatric acute respiratory distress syndrome severity were not associated with improved low-tidal volume ventilation adherence nor did adherence improve over time. Overweight children were less likely to receive low-tidal volume ventilation strategies in the first day of illness.