Variability in Cardiopulmonary Exercise Testing Biologic Controls.

Area of Science:

• Cardiopulmonary physiology
• Exercise science
• Biomedical engineering

Background:

• Cardiopulmonary exercise testing (CPET) is the gold standard for assessing exercise capacity.
• Quality control in CPET relies on quantifying measurement variability.
• Guidelines recommend biologic control testing, but data on its implementation are scarce.

Purpose of the Study:

• To describe the long-term variability of oxygen consumption (V̇O₂), carbon dioxide production (V̇CO₂), and minute ventilation (V̇E) during steady-state CPET.
• To establish a practical method for assessing and performing biologic control testing in CPET.

Main Methods:

• A prospective study involving 4 healthy subjects performing constant work rate exercise tests.
• Data were collected over a 1-year period using a computer-controlled cycle ergometer.
• Steady-state conditions were assessed by averaging data from the last 120 seconds at each work rate, with z-scores used to define significant variability (±1.96).

Main Results:

• Mean coefficients of variation (CoV) across all subjects and work rates were 6.59% for V̇O₂, 6.41% for V̇CO₂, and 6.32% for V̇E.
• ±1.96 z-scores corresponded to a 9.4-18.1% change in V̇O₂, 9.6-18.1% in V̇CO₂, and 9-21.5% in V̇E across workloads.

Conclusions:

• Long-term variability data for steady-state CPET measurements (V̇O₂, V̇CO₂, V̇E) during biologic control testing are reported.
• The use of ±1.96 z-scores provides a threshold to identify results exceeding expected variability.
• This approach aids in quality control and may prompt investigation of CPET instrumentation when variability is significant.