A validation and comparison study of two metabolic monitors

Area of Science:

• Physiological measurement
• Respiratory physiology
• Medical device validation

Background:

• Indirect calorimetry is crucial for assessing metabolic status.
• Portable metabolic carts offer clinical flexibility.
• Accurate validation of these devices is essential for reliable patient data.

Purpose of the Study:

• To validate the accuracy of two portable indirect calorimetry systems: Deltatrac Metabolic Monitor and 2900 MMC System.
• To assess their performance in measuring oxygen consumption (VO2) and carbon dioxide production (VCO2) under simulated physiological conditions.

Main Methods:

• Utilized a lung model to simulate varying levels of CO2 production (VCO2) and O2 consumption (VO2).
• Tested devices at different minute ventilation (VE) and fraction of inspired oxygen (FiO2) levels (0.21-0.80).
• Calculated overall measurement errors for both VO2 and VCO2 for each system.

Main Results:

• VCO2 measurement errors were 1.5% (Deltatrac) and 2.4% (2900 MMC).
• VO2 measurement errors were 1.9% (Deltatrac) and 3.2% (2900 MMC).
• Both systems showed comparable VO2 accuracy up to FiO2 0.60; Deltatrac demonstrated superior accuracy at FiO2 0.80.

Conclusions:

• Both Deltatrac and 2900 MMC metabolic cart systems provide valid measurements of VO2 and VCO2.
• The Deltatrac Metabolic Monitor exhibits enhanced accuracy for VO2 measurements at higher FiO2 levels.
• These findings support the use of these portable systems in clinical settings, with consideration for high FiO2 conditions.