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Quantifying altered oxygen kinetics and reducing metabolic test times for children with cerebral palsy: a
Pavreet K Gill1, J Maxwell Donelan1, Katherine M Steele2
1Department of Biomedical Physiology & Kinesiology, WearTech Labs, Simon Fraser University, Burnaby, British Columbia, Canada.
Insights
Children with cerebral palsy (CP) have slower oxygen uptake kinetics during walking, indicating metabolic control issues. A new Bayesian model accurately estimates oxygen cost in just 3 minutes, improving metabolic analysis efficiency for CP research.
Area of Science:
- Physiology
- Pediatrics
- Biomedical Engineering
Background:
- Children with cerebral palsy (CP) demonstrate elevated energetic costs during walking compared to typically developing peers.
- Direct measurement of oxygen cost via indirect calorimetry is challenging in this population.
- Oxygen uptake (V̇o2) kinetics differences between children with CP and controls are not well understood.
Purpose of the Study:
- To apply a dual-exponential Bayesian model to quantify V̇o2 kinetics in children with CP during walking.
- To assess the model's efficacy in estimating steady-state V̇o2 with reduced testing duration.
- To explore potential relationships between V̇o2 kinetics and CP characteristics.
Main Methods:
- A dual-exponential Bayesian model was employed to analyze V̇o2 responses to step changes in work rate.
- The time constant of the primary V̇o2 phase was calculated for 263 children with CP.
- Model performance for estimating steady-state V̇o2 was evaluated using 3 minutes versus 6 minutes of data.
Main Results:
- The median V̇o2 time constant in children with CP was 33.1 s, significantly longer than typically developing children.
- No significant differences in V̇o2 time constant were observed across Gross Motor Function Classification System (GMFCS) levels, sex, or age.
- The model accurately estimated steady-state V̇o2 using 3 minutes of data, explaining >95% of the variance with <5% mean absolute error compared to 6-minute estimates.
Conclusions:
- Slower V̇o2 kinetics in children with CP suggest potential impairments in metabolic regulation, contributing to increased energy expenditure.
- The validated 3-minute V̇o2 estimation method offers a more efficient and practical approach for metabolic assessments in children with CP.
- This methodology can facilitate more accurate and timely clinical and research analyses of walking energetics in pediatric CP.
Abstract:
Prior research using indirect calorimetry has shown that children with cerebral palsy (CP) exhibit significantly increased energetic costs during walking. However, metabolic testing to obtain oxygen cost is challenging. As a result, differences in oxygen uptake kinetics (V̇o2) in CP compared with their typically developing peers remain unexplored. Step changes in work rate have been shown to result in an exponential V̇o2 response with three distinct phases 1) cardiodynamic, 2) primary, and 3) steady-state. Here, we applied a dual-exponential Bayesian model to assess the time constant of the primary phase V̇o2 response from resting to walking in children with CP. In addition, we evaluated the model's ability to estimate steady-state V̇o2 using shorter test durations. From a sample of 263 children with CP, the median V̇o2 time constant was 33.1 s (5th-95th percentile range: 14.5-69.8 s), significantly longer than reported values for typically developing children (range of means: 10.2-31.6 s). Furthermore, the model accurately estimated steady-state V̇o2 using only the first 3 min of metabolic data compared with the typical 6 min used in current clinical practice. The 3-min estimate explained >95% of the 6-min estimate variance, with <5% mean absolute error. Slower oxygen kinetics in children with CP suggest impairments in metabolic control, potentially contributing to their higher energy demands. Although the exact mechanisms remain unclear, this study provides valuable insights into the walking energetics of children with CP and presents a more efficient method for analyzing V̇o2 for this population.NEW & NOTEWORTHY We used a Bayesian model to study oxygen kinetics in children with CP. First, we quantified the oxygen kinetics time constant, finding no significant differences across GMFCS, sex, or age despite slower kinetics compared with typically developing peers. Next, we validated the model's ability to estimate steady-state V̇o2 with only 3 min of data, halving the usual testing time. This method has important implications for faster, accurate metabolic analyses in clinical and research settings.
