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Trending of impedance-monitored cardiac variables: method and statistical power analysis of 100 control studies in a
J J Mickell1, S E Lucking, F C Chaten
1Department of Pediatrics, Children's Medical Center, Medical College of Virginia, Virginia Commonwealth University, Richmond.
Insights
The NCCOM3-R6 monitor accurately tracks cardiac output and other cardiovascular metrics in pediatric patients. Large sample sizes enable detection of significant clinical changes, ensuring reliable patient monitoring.
Area of Science:
- Cardiovascular Physiology
- Critical Care Medicine
- Biomedical Engineering
Background:
- Continuous hemodynamic monitoring is crucial in pediatric intensive care units (PICUs).
- Thoracic electrical bioimpedance (TEB) offers a non-invasive method for assessing cardiovascular function.
- The NCCOM3-R6 device utilizes TEB to measure cardiac output and other vital parameters.
Purpose of the Study:
- To evaluate the reliability and sensitivity of the NCCOM3-R6 monitor for continuous cardiovascular assessment in pediatric patients.
- To determine the feasibility of detecting clinically significant changes in cardiovascular variables using TEB monitoring in a large cohort.
- To establish the required sample size for detecting specific changes in cardiac output with adequate statistical power.
Main Methods:
- Data from 100 control studies involving 40 pediatric ICU patients (age 0.04-20.39 years) were analyzed.
- Cardiac output and five other cardiovascular variables were continuously monitored using the NCCOM3-R6 device.
- Data were averaged over 5-minute intervals for 130 minutes, with analysis of individual and aggregated study results.
Main Results:
- Individual 5-minute averages of cardiac output showed 99% agreement within +/- 44% of the baseline for each study.
- Aggregated data from 100 studies revealed no significant deviation from baseline for any measured variable over a 2-hour period (p > 0.70).
- A sample size of 100 studies allowed detection of a +/- 5% change in cardiac output with 95% power at p < 0.005.
Conclusions:
- The NCCOM3-R6 monitor provides reliable cardiovascular variable measurements in pediatric ICU patients.
- Sufficiently large sample sizes are essential for detecting subtle yet clinically significant hemodynamic changes using TEB.
- The NCCOM3-R6, with adequate sample size, can effectively identify pharmacologic or procedural impacts on cardiovascular status in critically ill children.
Abstract:
The NCCOM3-R6 monitor continuously monitors cardiac output and five other cardiovascular variables from the thoracic electrical bioimpedance signal. We averaged data over 5-min intervals for 130 min in 100 control studies in 40 pediatric ICU patients, age 0.04 to 20.39 yr (median 1.39) and weighing 2.0 to 59.5 kg (median 8.8). For individual studies, 99% of the 5-min averages of cardiac output fell within +/- 44% of the baseline cardiac output for that study. Normal ranges were somewhat narrower for the other five variables. When we averaged data for 100 studies, 5-min interval observations for each variable did not deviate from baseline over a 2-h period (p greater than .70). With a sample size of 100 studies, we could detect a change in cardiac output of +/- 5% at the p less than .005 level with a power of 0.95. We conclude that with a sufficiently large sample size, studies employing the NCCOM3 can detect clinically significant cardiovascular changes due to pharmacologic or procedural stressors.