Validity and reliability of a new whole room indirect calorimeter to assess metabolic response to small calorie loads.

We overview of our whole room indirect calorimeter (WRIC), demonstrate validity and reliability of our WRIC, and explore a novel application of Bayesian hierarchical modeling to assess responses to small carbohydrate loads. To assess WRIC validity seven gas infusion studies were performed using a gas blender and profiles designed to mimic resting and postprandial metabolic events. Sixteen participants underwent fasting and postprandial measurements, during which they consumed a 75-kcal drink containing sucrose, dextrose, or fructose in a crossover design. Linear mixed effects models were used to compare resting and postprandial metabolic rate (MR) and carbohydrate oxidation. Postprandial carbohydrate oxidation trajectories for each participant and condition were modeled using Bayesian Hierarchical Modeling. Mean total error in infusions were 1.27 ± 0.67% and 0.42 ± 0.70% for VO2 and VCO2 respectively, indicating a high level of validity. Mean resting MR was similar across conditions ([Formula: see text] = 1.05 ± 0.03 kcal/min, p = 0.82, ICC: 0.91). While MR increased similarly among all conditions (~13%, p = 0.29), postprandial carbohydrate oxidation parameters were significantly lower for dextrose compared with sucrose or fructose. We provide evidence validating our WRIC and a novel application of statistical methods useful for research using WRIC.

Validity and reliability of a new whole room indirect calorimeter to assess metabolic response to small-calorie loads.

Objective: To provide an overview of our whole room indirect calorimeter (WRIC), demonstrate validity and reliability of our WRIC, and explore a novel application of Bayesian hierarchical modeling to assess responses to small carbohydrate loads. Methods: Seven gas infusion studies were performed using a gas blender and profiles designed to mimic resting and postprandial metabolic events to assess WRIC validity. In a crossover design, 16 participants underwent fasting and postprandial measurements, during which they consumed a 75-kcal drink containing sucrose, dextrose, or fructose. Linear mixed effects models were used to compare resting and postprandial metabolic rate (MR) and CO (CO). Bayesian Hierarchical Modeling was also used to model postprandial CO trajectories for each participant and condition. Results: Mean total error in infusions were 1.27 ± 1.16% and 0.42 ± 1.21% for VO2 and VCO2 respectively, indicating a high level of validity. Mean resting MR was similar across conditions (x¯=1.05±0.03 kcal/min, p=0.82, ICC: 0.91). While MR increased similarly among all conditions (~13%, p=0.29), postprandial CO parameters were significantly lower for dextrose compared with sucrose or fructose. Conclusions: Our WRIC validation and novel application of statistical methods presented here provide important foundations for new research directions using WRIC.

Using a smartphone application to capture daily work activities: a longitudinal pilot study in a farming population.

OBJECTIVES: Smartphones are increasingly used to collect real-time information on time-varying exposures. We developed and deployed an application (app) to evaluate the feasibility of using smartphones to collect real-time information on intermittent agricultural activities and to characterize agricultural task variability in a longitudinal study of farmers. METHODS: We recruited 19 male farmers, aged 50-60 years, to report their farming activities on 24 randomly selected days over 6 months using the Life in a Day app. Eligibility criteria include personal use of an iOS or Android smartphone and >4 h of farming activities at least two days per week. We developed a study-specific database of 350 farming tasks that were provided in the app; 152 were linked to questions that were asked when the activity ended. We report eligibility, study compliance, number of activities, duration of activities by day and task, and responses to the follow-up questions. RESULTS: Of the 143 farmers we reached out to for this study, 16 were not reached by phone or refused to answer eligibility questions, 69 were ineligible (limited smartphone use and/or farming time), 58 met study criteria, and 19 agreed to participate. Refusals were mostly related to uneasiness with the app and/or time commitment (32 of 39). Participation declined gradually over time, with 11 farmers reporting activities through the 24-week study period. We obtained data on 279 days (median 554 min/day; median 18 days per farmer) and 1,321 activities (median 61 min/activity; median 3 activities per day per farmer). The activities were predominantly related to animals (36%), transportation (12%), and equipment (10%). Planting crops and yard work had the longest median durations; short-duration tasks included fueling trucks, collecting/storing eggs, and tree work. Time period-specific variability was observed; for example, crop-related activities were reported for an average of 204 min/day during planting but only 28 min/day during pre-planting and 110 min/day during the growing period. We obtained additional information for 485 (37%) activities; the most frequently asked questions were related to "feed animals" (231 activities) and "operate fuel-powered vehicle (transportation)" (120 activities). CONCLUSIONS: Our study demonstrated feasibility and good compliance in collecting longitudinal activity data over 6 months using smartphones in a relatively homogeneous population of farmers. We captured most of the farming day and observed substantial heterogeneity in activities, highlighting the need for individual activity data when characterizing exposure in farmers. We also identified several areas for improvement. In addition, future evaluations should include more diverse populations.

Closed-loop control of air supply to whole-room indirect calorimeters to improve accuracy and standardize measurements during 24-hour dynamic metabolic studies.

OBJECTIVE: The aim of this study was to test proportional-integral-derivative (PID) control of air inflow rate in a whole-room indirect calorimeter to improve accuracy in measuring oxygen (O2 ) consumption ( V ̇ O 2 ) and carbon dioxide (CO2 ) production ( V ̇ CO 2 ). METHODS: A precision gas blender infused nitrogen (N2 ) and CO2 into the calorimeter over 24 hours based on static and dynamic infusion profiles mimicking V ̇ O 2 and V ̇ CO 2 patterns during resting and non-resting conditions. Constant (60 L/min) versus time-variant flow set by a PID controller based on the CO2 concentration was compared based on errors between measured versus expected values for V ̇ O 2 , V ̇ CO 2 , respiratory exchange ratio, and metabolic rate. RESULTS: Compared with constant inflow, the PID controller allowed both a faster rise time and long-term maintenance of a stable CO2 concentration inside the calorimeter, resulting in more accurate V ̇ CO 2 estimates (mean hourly error, PID: -0.9%, 60 L/min = -2.3%, p < 0.05) during static infusions. During dynamic infusions mimicking exercise sessions, the PID controller achieved smaller errors for V ̇ CO 2 (mean: -0.6% vs. -2.7%, p = 0.02) and respiratory exchange ratio (mean: 0.5% vs. -3.1%, p = 0.02) compared with constant inflow conditions, with similar V ̇ O 2 (p = 0.97) and metabolic rate (p = 0.76) errors. CONCLUSIONS: PID control in a whole-room indirect calorimeter system leads to more accurate measurements of substrate oxidation during dynamic metabolic studies.

Protocol for the Development of a Behavioral Family Lifestyle Intervention Supported by Mobile Health to Improve Weight Self-Management in Children With Asthma and Obesity.

BACKGROUND: Asthma is the most common chronic childhood illness and is a leading cause of emergency department visits in the United States. Obesity increases the risk of poor health outcomes, reduced quality of life, and increased health care expenditures among youth with asthma. Weight loss is crucial for improving asthma outcomes in children with obesity. Our study team developed the Childhood Health and Asthma Management Program (CHAMP), a 16-session behavioral family lifestyle intervention (BFI) for school-age children with asthma and obesity and evaluated CHAMP in a randomized controlled trial compared with attention control. There were medium effect sizes favoring CHAMP for changes in body mass index z-scores, asthma control, and lung function among completers (ie, those who attended ≥9 of 16 sessions). Despite high rates of satisfaction reported by families, attendance and trial attrition were suboptimal, which raised concerns regarding the feasibility of CHAMP. Qualitative feedback from participants indicated 3 areas for refinement: (1) a less burdensome intervention modality, (2) a more individually tailored intervention experience, and (3) that interventionists can better answer health-related questions. OBJECTIVE: We propose to improve upon our pilot intervention by developing the Mobile Childhood Health and Asthma Management Program (mCHAMP), a nurse-delivered BFI, delivered to individual families, and supported by a mobile health (mHealth) app. This study aims to (1) identify structural components of mCHAMP and (2) develop and test the usability of our mCHAMP app. METHODS: Participants will be recruited from an outpatient pediatric pulmonary clinic. We will identify the structural components of mCHAMP by conducting a needs assessment with parents of children with asthma and obesity. Subsequently, we will develop and test our mCHAMP app using an iterative process that includes usability testing with target users and pediatric nurses. RESULTS: This study was funded in 2018; 13 parents of children with asthma and obesity participated in the needs assessment. Preliminary themes from focus groups and individual meetings included barriers to engaging in health-promoting behaviors, perceived relationships between asthma and obesity, facilitators to behavior change, and intervention preferences. Participatory design sessions and usability testing are expected to conclude in late 2019. CONCLUSIONS: Outcomes from this study are expected to include an mHealth app designed with direct participation from the target audience and usability data from stakeholders as well as potential end users. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/13549.

Topical Review: Design Considerations When Creating Pediatric Mobile Health Interventions: Applying the IDEAS Framework.

OBJECTIVE: To present a guiding framework from the perspective of psychologists and technologists to develop effective mobile health (mHealth) interventions for pediatric populations. METHODS: This topical review uses the IDEAS framework as an organizational method to summarize current strategies to conceptualize, design, evaluate, and disseminate mHealth interventions. RESULTS: Incorporating theories of behavior change and feedback from target populations are essential when developing mHealth interventions. Following user-centered approaches that fully incorporate end users into design and development stages increases the likelihood that the intervention will be acceptable. Iterative design cycles and prototyping are important steps to gather user feedback to optimize an mHealth intervention. Broad sharing of knowledge and products generated during intervention development also is recommended. Assessment of behavioral principles, intervention components, or a full intervention package should be conducted to evaluate usability and efficacy. CONCLUSIONS: Pediatric health-care researchers and clinicians are increasingly using mHealth technology to target health behaviors and improve related outcomes. Pediatric psychologists should consider applying the design strategies outlined in the IDEAS framework to produce and disseminate mHealth interventions tailored to the specific needs of pediatric populations.

Activity Tracking with Momentary Assessments.

Task and activity tracking has been an effective industrial management and research technique for generations. It is applied to workflow optimization, group coordination, task sequencing, individual time management and environmental exposures. Appropriately, task tracking technologies are migrating to personal mobile devices. At the same time, individual survey approaches have been advanced tremendously as mobile apps. We report on a method of dynamic task registration with momentary assessment systems in natural environments that apply knowledge of context. We describe how the app was refined by a user acceptance study and its deployment in studies on agricultural exposure and industrial operations.

Multi-sensor ecological momentary assessment of behavioral and psychosocial predictors of weight loss following bariatric surgery: study protocol for a multicenter prospective longitudinal evaluation.

BACKGROUND: Bariatric surgery is currently the most effective strategy for producing significant and durable weight loss. Yet, not all patients achieve initial weight loss success and some degree of weight regain is very common, sometimes as early as 1-2 years post-surgery. Suboptimal weight loss not fully explained by surgical, demographic, and medical factors has led to greater emphasis on patient behaviors evidenced by clinical guidelines for appropriate eating and physical activity. However, research to inform such guidelines has often relied on imprecise measures or not been specific to bariatric surgery. There is also little understanding of what psychosocial factors and environmental contexts impact outcomes. To address research gaps and measurement limitations, we designed a protocol that innovatively integrates multiple measurement tools to determine which behaviors, environmental contexts, and psychosocial factors are related to outcomes and explore how psychosocial factors/environmental contexts influence weight. This paper provides a detailed description of our study protocol with a focus on developing and deploying a multi-sensor assessment tool to meet our study aims. METHODS: This NIH-funded prospective cohort study evaluates behavioral, psychosocial, and environmental predictors of weight loss after bariatric surgery using a multi-sensor platform that integrates objective sensors and self-report information collected via smartphone in real-time in patients' natural environment. A target sample of 100 adult, bariatric surgery patients (ages 21-70) use this multi-sensor platform at preoperative baseline, as well as 3, 6, and 12 months postoperatively, to assess recommended behaviors (e.g., meal frequency, physical activity), psychosocial indicators with prior evidence of an association with surgical outcomes (e.g., mood/depression), and key environmental factors (e.g., type/quality of food environment). Weight also is measured at each assessment point. DISCUSSION: This project has the potential to build a more sophisticated and valid understanding of behavioral and psychosocial factors contributing to success and risk after bariatric surgery. This new understanding could directly contribute to improved (i.e., specific, consistent, and validated) guidelines for recommended pre- and postoperative behaviors, which could lead to improved surgical outcomes. These data will also inform behavioral, psychosocial, and environmental targets for adjunctive interventions to improve surgical outcomes. TRIAL REGISTRATION: Registered trial NCT02777177 on 5/19/2016.

Improving temporal accuracy of human metabolic chambers for dynamic metabolic studies.

Metabolic chambers are powerful tools for assessing human energy expenditure, providing flexibility and comfort for the subjects in a near free-living environment. However, the flexibility offered by the large living room size creates challenges in the assessment of dynamic human metabolic signals-such as those generated during high-intensity interval training and short-term involuntary physical activities-with sufficient temporal accuracy. Therefore, this paper presents methods to improve the temporal accuracy of metabolic chambers. The proposed methods include 1) adopting a shortest possible step size, here one minute, to compute the finite derivative terms for the metabolic rate calculation, and 2) applying a robust noise reduction method-total variation denoising-to minimize the large noise generated by the short derivative term whilst preserving the transient edges of the dynamic metabolic signals. Validated against 24-hour gas infusion tests, the proposed method reconstructs dynamic metabolic signals with the best temporal accuracy among state-of-the-art approaches, achieving a root mean square error of 0.27 kcal/min (18.8 J/s), while maintaining a low cumulative error in 24-hour total energy expenditure of less than 45 kcal/day (188280 J/day). When applied to a human exercise session, the proposed methods also show the best performance in terms of recovering the dynamics of exercise energy expenditure. Overall, the proposed methods improve the temporal resolution of the chamber system, enabling metabolic studies involving dynamic signals such as short interval exercises to carry out the metabolic chambers.

Applying Interactive Mobile health to Asthma Care in Teens (AIM2ACT): Development and design of a randomized controlled trial.

Early adolescents have difficulties performing asthma self-management behaviors, placing them at-risk for poor asthma control and reduced quality of life. This paper describes the development and plans for testing an interactive mobile health (mHealth) tool for early adolescents, ages 12-15years, and their caregivers to help improve asthma management. Applying Interactive Mobile health to Asthma Care in Teens (AIM2ACT) is informed by the Pediatric Self-management model, which posits that helpful caregiver support is facilitated by elucidating disease management behaviors and allocating treatment responsibility in the family system, and subsequently engaging in collaborative caregiver-adolescent asthma management. The AIM2ACT intervention was developed through iterative feedback from an advisory board composed of adolescent-caregiver dyads. A pilot randomized controlled trial of AIM2ACT will be conducted with 50 early adolescents with poorly controlled asthma and a caregiver. Adolescent-caregiver dyads will be randomized to receive the AIM2ACT smartphone application (AIM2ACT app) or a self-guided asthma control condition for a 4-month period. Feasibility and acceptability data will be collected throughout the trial. Efficacy outcomes, including family asthma management, lung function, adolescent asthma control, asthma-related quality of life, and self-efficacy for asthma management, will be collected at baseline, post-treatment, and 4-month follow-up. Results from the current study will inform the utility of mHealth to foster the development of asthma self-management skills among early adolescents.

Effects of 13-Hour Hyperglucagonemia on Energy Expenditure and Hepatic Glucose Production in Humans.

Glucagon (GCG) acutely stimulates energy expenditure (EE) and hepatic glucose production (HGP) in humans, but whether these effects persist during hyperglucagonemia of longer duration is unclear. Using a prospective, randomized, single-blind, crossover study design, we therefore measured EE and rates of glucose appearance (glucose RA) during three separate infusion protocols in healthy lean males: A) 10-h overnight GCG infusion (6 ng/[kg × min]) followed by 3-h infusion of GCG, octreotide (OCT), and insulin (INS) for basal replacement; B) overnight saline (SAL) infusion followed by GCG/OCT/INS infusion; and C) overnight SAL infusion followed by SAL/OCT/INS infusion. Sleep EE, measured at 6 to 7 h of the overnight infusion, was increased 65-70 kcal/24 h in A compared with B and C. During the 3-h infusion, mean resting EE remained significantly increased in A versus C by ∼50 kcal/24 h; in B, resting EE increased with a statistical trend but was not significantly greater than in C. Glucose RA increased to comparable levels in A and B. We conclude that in healthy lean males, stimulation of EE and HGP is sustained during hyperglucagonemia of longer duration when insulin secretion is inhibited. The increase in EE at the present GCG dose was of marginal clinical significance.

The Physical Activity and Redesigned Community Spaces (PARCS) Study: Protocol of a natural experiment to investigate the impact of citywide park redesign and renovation.

BACKGROUND: The built environment plays a critical role in promoting physical activity and health. The association between parks, as a key attribute of the built environment, and physical activity, however, remains inconclusive. This project leverages a natural experiment opportunity to assess the impact of the Community Parks Initiative (CPI), a citywide park redesign and renovation effort in New York City, on physical activity, park usage, psychosocial and mental health, and community wellbeing. METHODS: The project will use a longitudinal design with matched controls. Thirty intervention park neighborhoods are socio-demographically matched to 20 control park neighborhoods. The study will investigate whether improvements in physical activity, park usage, psychosocial and mental health, and community wellbeing are observed from baseline to 3 years post-renovation among residents in intervention vs. control neighborhoods. DISCUSSION: This study represents a rare opportunity to provide robust evidence to further our understanding of the complex relationship between parks and health. Findings will inform future investments in health-oriented urban design policies and offer evidence for addressing health disparities through built environment strategies.

Integrating mHealth and Systems Science: A Combination Approach to Prevent and Treat Chronic Health Conditions.

Chronic health conditions are a growing global health concern and account for over half of all deaths worldwide. Finding ways to decrease the burden of and resources allotted to chronic health conditions is of primary importance. Recent advances in technology and insights into modeling techniques offer promising approaches, which if combined, represent a novel direction that would further advance the prevention and treatment of chronic health conditions.

A mobile phone food record app to digitally capture dietary intake for adolescents in a free-living environment: usability study.

BACKGROUND: Mobile technologies are emerging as valuable tools to collect and assess dietary intake. Adolescents readily accept and adopt new technologies; thus, a food record app (FRapp) may be a useful tool to better understand adolescents' dietary intake and eating patterns. OBJECTIVE: We sought to determine the amenability of adolescents, in a free-living environment with minimal parental input, to use the FRapp to record their dietary intake. METHODS: Eighteen community-dwelling adolescents (11-14 years) received detailed instructions to record their dietary intake for 3-7 days using the FRapp. Participants were instructed to capture before and after images of all foods and beverages consumed and to include a fiducial marker in the image. Participants were also asked to provide text descriptors including amount and type of all foods and beverages consumed. RESULTS: Eight of 18 participants were able to follow all instructions: included pre- and post-meal images, a fiducial marker, and a text descriptor and collected diet records on 2 weekdays and 1 weekend day. Dietary intake was recorded on average for 3.2 (SD 1.3 days; 68% weekdays and 32% weekend days) with an average of 2.2 (SD 1.1) eating events per day per participant. A total of 143 eating events were recorded, of which 109 had at least one associated image and 34 were recorded with text only. Of the 109 eating events with images, 66 included all foods, beverages and a fiducial marker and 44 included both a pre- and post-meal image. Text was included with 78 of the captured images. Of the meals recorded, 36, 33, 35, and 39 were breakfasts, lunches, dinners, and snacks, respectively. CONCLUSIONS: These data suggest that mobile devices equipped with an app to record dietary intake will be used by adolescents in a free-living environment; however, a minority of participants followed all directions. User-friendly mobile food record apps may increase participant amenability, increasing our understanding of adolescent dietary intake and eating patterns. To improve data collection, the FRapp should deliver prompts for tasks, such as capturing images before and after each eating event, including the fiducial marker in the image, providing complete and accurate text information, and ensuring all eating events are recorded and should be customizable to individuals and to different situations. TRIAL REGISTRATION: Clinicaltrials.gov NCT01803997. http://clinicaltrials.gov/ct2/show/NCT01803997 (Archived at: http://www.webcitation.org/6WiV1vxoR).

B-MOBILE--a smartphone-based intervention to reduce sedentary time in overweight/obese individuals: a within-subjects experimental trial.

PURPOSE: Excessive sedentary time (SED) has been linked to obesity and other adverse health outcomes. However, few sedentary-reducing interventions exist and none have utilized smartphones to automate behavioral strategies to decrease SED. We tested a smartphone-based intervention to monitor and decrease SED in overweight/obese individuals, and compared 3 approaches to prompting physical activity (PA) breaks and delivering feedback on SED. DESIGN AND METHODS: Participants [N = 30; Age = 47.5(13.5) years; 83% female; Body Mass Index (BMI) = 36.2(7.5) kg/m2] wore the SenseWear Mini Armband (SWA) to objectively measure SED for 7 days at baseline. Participants were then presented with 3 smartphone-based PA break conditions in counterbalanced order: (1) 3-min break after 30 SED min; (2) 6-min break after 60 SED min; and (3) 12-min break after 120 SED min. Participants followed each condition for 7 days and wore the SWA throughout. RESULTS: All PA break conditions yielded significant decreases in SED and increases in light (LPA) and moderate-to-vigorous PA (MVPA) (p<0.005). Average % SED at baseline (72.2%) decreased by 5.9%, 5.6%, and 3.3% [i.e. by mean (95% CI) -47.2(-66.3, -28.2), -44.5(-65.2, -23.8), and -26.2(-40.7, -11.6) min/d] in the 3-, 6-, and 12-min conditions, respectively. Conversely, % LPA increased from 22.8% to 26.7%, 26.7%, and 24.7% [i.e. by 31.0(15.8, 46.2), 31.0(13.6, 48.4), and 15.3(3.9, 26.8) min/d], and % MVPA increased from 5.0% to 7.0%, 6.7%, and 6.3% (i.e. by 16.2(8.5, 24.0), 13.5(6.3, 20.6), and 10.8(4.2, 17.5) min/d] in the 3-, 6-, and 12-min conditions, respectively. Planned pairwise comparisons revealed the 3-min condition was superior to the 12-min condition in decreasing SED and increasing LPA (p<0.05). CONCLUSION: The smartphone-based intervention significantly reduced SED. Prompting frequent short activity breaks may be the most effective way to decrease SED and increase PA in overweight/obese individuals. Future investigations should determine whether these SED reductions can be maintained long-term. TRIAL REGISTRATION: ClinicalTrials.gov NCT01688804.

Energy expenditure: measurement of human metabolism.

Obesity is one of the most prevalent chronic diseases globally, especially in the United States. While the United States gained an early lead in unnecessary weight gain, most other countries are quickly closing the gap. The latest U.S. National Health and Nutrition Examination Survey (NHANES, http://www.cdc.gov/nchs/nhanes.htm) documents that about one third of adults in the United States are now overweight [a body-mass index (BMI) between 25 and 30 kg/m2] and another one third (61 million) are considered obese (BMI >30 kg/m2). Being obese is a strong risk factor for cardiovascular diseases, type 2 diabetes, osteoporosis, some cancers, and depression. The economic impact of this condition is staggering: in 2008, more than 147 billion dollars were spent just in the United States for medical costs related to obesity. Time lost from work and spending on weight loss costs even more.

Data upload capability of 3G mobile phones.

Mobile phones are becoming an important platform to measure free-living energy balance and to support weight management therapies. Sensor data, camera images and user input are needed by clinicians and researchers in close to real time. We assessed upload (reverse link) data transport rates for 2007-2008 model mobile phones on two major US wireless systems. Even the slowest phone (EVDO Rev 0) reliably uploaded 40 MB of data in less than 1 h. More than 95% of file uploads were successful in tests that simulated normal phone use over 3 d. Practical bandwidth and data currency from typical smart phones will likely keep pace with the data needs of energy balance studies and weight management therapy.

Smart phones are useful for food intake and physical activity surveys.

Current self-report methods of recording food intake and Physical Activity (PA) are cumbersome and inaccurate. Food and activity surveys implemented on a smart phone will allow for immediate entry, data transfer to a researcher, and feedback to the user. Ten subjects followed a script, representative of one day, to enter food intake and PA on a smart phone. In the follow-up report, all subjects were interested in using the tested program to compare food intake with PA to predict weight gain and loss.

Comparison of Centrifugal and Roller Pump Hemolysis Rates at Low Flow.

We compared in vitro rates of hemolysis for a recently developed centrifugal pump with a conventional roller pump (10-10-00; Stöckert, Munich, Germany). Flow rates of 0.3 L/min and 1 L/min and a pressure of 200 mm Hg were chosen to simulate conditions during neonatal extracorporeal membrane oxygenation (ECMO). There was no significant difference in hemolysis rates between centrifugal and roller pumps (p = 0.57) nor between high and low flow (p = 0.86). The centrifugal pump caused no more blood trauma than the roller pump at the low-flow/high-pressure conditions required for neonatal ECMO. The Nikkiso pump is superior to roller pumps in size and priming volume (25 ml) and may permit development of a smaller and simpler ECMO system.