The Ultimate Laboratory Standard

Detail of Set Point Controller

Why Metabolic Calibration?

Ideally, the respiratory and metabolic variables (TV, RR, VE, VO2, VCO2) generated by the simulator should be indistinguishable from those produced by humans. The simulator produces and controls those variables very precisely. Consequently, one can test any breath-by-breath or mixing chamber metabolic measurement system with high accuracy and full confidence.

Metabolic Calibration uses the principle of mass preservation to create known VO2 and VCO2. The principle of mass preservation dictates that the chosen mass flow of CO2 and O2 remains unchanged regardless of the ventilatory dilution (i.e. the minute ventilation that delivers it into the system under calibration).

This top-of-the-line metabolic calibration gas titration device consists of a Mass Flow Controller capable of delivering any set point flow of this gas (~21%CO2, 79%N2) within a range of 0 - 20 liters/min STPD and a Set Point Module (SPM) which enables selection of desired mass flows.

Four switch-selected VO2 settings are 1, 2, 3 and 4 liters per minute of VO2 and VCO2. (Model 17057 has additional 5 and 6-liter settings) The exact value will depend on physical parameters, such as barometric pressure, air temperature, and relative humidity. The provided O2CAL.xls spreadsheet software enables precise determination of the selected metabolic rate and the percentage error of the metabolic measurement system being calibrated.

The remaining two positions of the rotary switch correspond to a Zero flow setting and a continuous 10-turn potentiometer-operated selection of any desired mass flow from zero to 4 L/min (5 & 6 L/min for model 17057).

Metabolic Calibration accuracy is +/-1% VO2 & VCO2.

Most flow sensors are typically calibrated with a fixed-volume manual syringe, but little is known about the performance of that flow sensor over the whole physiological range.

This device includes a mass flow controller to produce precise Metabolic Calibration gas mixtures to verify VO2 and VCO2. It provides the highest accuracy and ease of adjustment.

So how does this affect the accuracy of your ventilation measurements (and ultimately VO2) when you have calibrated the flow sensor at some unknown manual stroke speed, then use the sensor for low-flow pediatric or resting measurements, or high-flow VO2max measurements?

What this device can be used for:

• Produce an exact, simulated VO2 and VCO2 to verify the overall accuracy of a metabolic measurement system and its software.
• Check the accuracy of any flow / volume measurement device.
• Simulate breathing at rates from 6 to 80 breaths per minute.
• Check the effects of various gas mixtures on a flow sensor.

Specifications

Model 17056 Stroke Volume Accuracy: +/-1/2%

Model 17057 Stroke Volume Accuracy between 600cc to 5000cc = +/- 1/2%
between 300cc and 600cc = +/- 1 to 2 %
Not recommended below 300cc

Motor speed is continuously variable from approx. 6 to 80 strokes per minute.

Digital Display: Breaths per minute
Mass and volumetric flow of calibration gas
Barometric Pressure
Temperature

Stroke Volume for model 17056 (Preset stops)
0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 liters

Stroke volume for model 17056-4L
1.0, 1.5, 2.0, 2.5, 3.0, 3.0, 4.0 liters

Stroke volume for model 17057
1.0, 2.0, 3.0, 4.0, 5.0 liters

(Other volume settings available on special order)

#17056 Size: 12" (31cm) wide x 16" (41cm) high x 29" (74cm) long

Voltage: 110 / 220 VAC (Specify)

Weight: Approx 40 pounds (18 kg)

A Metabolic Calibration gas containing 20.9% CO2, balance N2, is required.

Included is an Excel file that allows you to make the required BTPS/STPD corrections automatically and print a calibration report.

Other possible uses of this device:

• This variable speed motor-driven calibration syringe will check the accuracy and repeatability of any flow sensor over the range from 3 to 240 L/min of VE.
   
• Produce any mixture of two gases and
  change that mixture on-the-fly.
  (Dilution formula available from VacuMed)
   
• Generate custom low-O2 mixtures for
  simulated high altitude training.
   
• Quality Control of flow/volume sensing devices

If you want to read more about Metabolic Calibration, click on "Dr. Andrew's Corner" and check out references 1 and 2.

References:

1. HUSZCZUK, A., B.J. WHIPP, and K. WASSERMAN. A respiratory gas exchange simulator for routine calibration in metabolic studies. Eur. Respir. J. 3:465-468, 1990

2. GORE, C.J., P.G. CATCHESIDE, S.N. FRENCH, J.M. BENNETT, and J. LAFORGIA. Automated VO2 max calibrator for open-circuit indirect calorimetry systems. Med.Sci. Sports Exerc 29:1095-1103, 1997
 

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We also offer Metabolic Calibration of any Metabolic Measurement System in your lab.

Last Updated: 25 Jan 2024

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