Gas Anaylzers

Gas Chromatography (Absorption Type) Sample gas moves through a [blank_start]separator[blank_end] column where the differing sizes of molecules for the individual gases make each gas exit at a different [blank_start]rate[blank_end],

Advantages: Analyzes [blank_start]many gases[blank_end] at once. Very accurate Disadvantages: Requires more [blank_start]time[blank_end] than other analyzers. Affected by: [blank_start]H2O[blank_end] and [blank_start]CO2[blank_end] Measures: [blank_start]Ne[blank_end], [blank_start]O2[blank_end], [blank_start]N2[blank_end], [blank_start]CO[blank_end]

Mass Spectometry Function: Sample is drawn in by vacuum to the [blank_start]ionization[blank_end] chamber. Individual gases are [blank_start]separated[blank_end] and analyzed. Measures: Gas percentages Advantages: [blank_start]Rapid[blank_end] Response time, breath by breath analysis, multiple gas analysis Can analyze: [blank_start]He[blank_end], [blank_start]N2[blank_end], [blank_start]O2[blank_end], [blank_start]CO2[blank_end] Disadvantages: Expensive, large, high maintenance Most Suitable for: analysis of [blank_start]several[blank_end] patient at once rather than individual testing.

CO2/CO/CH4 AKA: Infrared Absorption Analyzer Quick response time is suitable for [blank_start]DLCO[blank_end] Calibrate: to room air ([blank_start]0[blank_end]%) and known concentration ([blank_start].3[blank_end]%) CO then re-zero and use [blank_start]gain[blank_end] to match read out to [blank_start]known[blank_end] concentration. Changes in altitude do [blank_start]NOT[blank_end] affect readings.

Helium analyzer Also Known as: [blank_start]Thermal[blank_end] Conductivity or [blank_start]Wheatstone[blank_end] Bridge Measures: Gas [blank_start]percentage[blank_end] Calibration: To room air ([blank_start]0[blank_end]%) and known ([blank_start]10[blank_end]%) then use gain to adjust to [blank_start]known[blank_end] amount. Do not use with [blank_start]flammable[blank_end] gases. Used with Helium dilution tests.

Nitrogen analyzer Also known as: [blank_start]Geissler[blank_end] Tube Ionizer Sample is pumped into [blank_start]ionization[blank_end] chamber where light is emitted and monitored by a phototube. Intensity of light is directly [blank_start]proportional[blank_end] to N2% Measures gas percentage Capable of breath by breath analysis Calibration: To zero with [blank_start]100[blank_end]% O2 and a [blank_start]known[blank_end] concentration.

O2 Analyzers Galvanic [blank_start]Fuel[blank_end] Cell Analyzer: Measures partial [blank_start]pressure[blank_end] and displays [blank_start]FiO2[blank_end] as %. If unable to calibrate you should replace the [blank_start]fuel[blank_end] cell. Calibration during exercise testing: Low [blank_start]12[blank_end]-[blank_start]14[blank_end]% and high [blank_start]21[blank_end]% Poloragraphic Analyzer Similar to galvanic but uses a [blank_start]battery[blank_end] Analogous to the [blank_start]Clark[blank_end] electrode Calibration is to [blank_start]21[blank_end]% and [blank_start]100[blank_end]%

Gas & Water Absorbers CO2 Absorber: AKA Sodium [blank_start]Hydroxide[blank_end], NaOH (soda [blank_start]lime[blank_end] or soda-sorb), Baralyme Required for [blank_start]rebreathing[blank_end] tests (FRC by He Dilution, DLCO-RB) Replace scrubber: When [blank_start]exhausted[blank_end], when [blank_start]color[blank_end] changes, or weekly. CO2 Scrubber produce [blank_start]water[blank_end] as a by product and should be placed [blank_start]upstream[blank_end] from water absorbers.

Gas & Water Absorbers Water Absorber ([blank_start]Dessicant[blank_end]) Drierite ([blank_start]Calcium[blank_end] Sulfate) Removes moisture as patient breathes through system. Proper placement of absorbers: 1st: [blank_start]CO2[blank_end] Absorber 2nd: [blank_start]H2O[blank_end] Absrober 3rd: Anaylzer Permapure (fafion Tubing) Conditions gas to [blank_start]equilibrate[blank_end] with ambient humidity Allows for accurate correction for humidity in a gas sample.